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UBC Theses and Dissertations

Slope stability and groundwater hydrology research for pitwall design at Equity Silver Mines Ltd., Houston,… Sperling, Antonin 1985

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SLOPE S T A B I L I T Y AND GROUNDWATER HYDROLOGY RESEARCH FOR PITWALL DESIGN AT EQUITY SILVER MINES LTD. HOUSTON, B R I T I S H COLUMBIA BY ANTONIN SPERLING B . A . S c , The U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1983 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF A P P L I E D SCIENCE THE FACULTY OF ( D e p a r t m e n t o f M i n i n g and I n GRADUATE STUDIES M i n e r a l P r o c e s s E n g i n e e r i n g We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF B R I T I S H COLUMBIA A P R I L 1985 (c) A n t o n i n S p e r l i n g , 1985 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y a v a i l a b l e for reference and study. I further agree that permission for extensive copying of t h i s thesis f o r scholarly purposes may be granted by the head of my department or by h i s or her representatives. I t i s understood that copying or publication of t h i s thesis f o r f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of M i n i n g and M i n e r a l P r o c e s s E n g i n e e r i n g The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date 85/04/18 s u p e r v i s o r : P r o f . CO. Brawner ABSTRACT S t r u c t u r a l geology, groundwater, shear s t r e n g t h and b l a s t i n g c o n t r o l p i t w a l l s t a b i l i t y at Equity S i l v e r Mines, Houston, B r i t i s h Columbia. A g e o t e c h n i c a l i n v e s t i g a t i o n of, these parameters was c a r r i e d out i n the Main Zone p i t during the summer of 1984. The o b j e c t i v e of the study was t o develop a p i t w a l l design based on g e o l o g i c and groundwater c o n d i t i o n s observed i n each design s e c t o r . This t h e s i s presents the r e s u l t s of the i n v e s t i g a t i o n ; methods of improving s t a b i l i t y by drainage and c o n t r o l b l a s t i n g are a l s o d i s c u s s e d . Information on s t r u c t u r a l geology was obtained by l i n e mapping of e x i s t i n g berms. The discodat package of computer programs was used t o process the s t r u c t u r a l data and t o i d e n t i f y trends i n o r i e n t a t i o n of d i s c o n t i n u i t i e s . Based on t h i s i n f o r m a t i o n , the Main Zone p i t was d i v i d e d i n t o ten design s e c t o r s , each s e c t o r having a c o n s i s t e n t p a t t e r n of d i s c o n t i n u i t y o r i e n t a t i o n s , rock type, groundwater c o n d i t i o n s and p i t w a l l o r i e n t a t i o n . K i n e m a t i c a l l y p o s s i b l e f a i l u r e modes were i d e n t i f i e d i n each design s e c t o r . F a i l u r e modes that were expected t o present s t a b i l i t y problems were analyzed t o c a l c u l a t e f a c t o r of s a f e t y . P i t w a l l and berm face angles were then s e l e c t e d such that only a s m a l l number of p o t e n t i a l f a i l u r e modes w i l l d a y l i g h t . The s t a b i l i t y e v a l u a t i o n has shown that i t should be p o s s i b l e t o increase p i t w a l l angles by 5* i n the west h a l f of the p i t . However, the data base i n t h i s area of the p i t i s p r e s e n t l y l i m i t e d because only a small number of berms are exposed. Therefore, a d d i t i o n a l l i n e mapping w i l l be r e q u i r e d before the west w a l l design can be f i n a l i z e d . i i Groundwater w i l l reduce p i t w a l l s t a b i l i t y , e s p e c i a l l y i n the east h a l f of the Main Zone p i t . Multi-berm f a i l u r e s are very s e n s i t i v e t o groundwater c o n d i t i o n s . A dewatering system should be i n s t a l l e d i n the Main Zone p i t t o minimize the p o s s i b i l i t y of such f a i l u r e s o ccuring. Wet b l a s t h o l e s d i c t a t e t h a t expensive water r e s i s t a n t s l u r r y e x p l o s i v e s be used i n many areas of the Main Zone p i t . The dewatering system should a l s o draw down the water t a b l e so b l a s t h o l e s w i l l become dryer and l e s s expensive ANFO can be u t i l i z e d . The magnitude of shear s t r e n g t h on f a i l u r e s u r f aces i s r e q u i r e d i n order t o evaluate s t a b i l i t y of p o t e n t i a l f a i l u r e s . S l i p t e s t s , p o i n t load t e s t s and back analyses of e x i s t i n g f a i l u r e s were used t o determine the shear s t r e n g t h parameters. Further s t u d i e s should be c a r r i e d out t o b e t t e r define the parameters at higher s t r e s s l e v e l s that w i l l develop i n a multi-berm f a i l u r e . Further p o t e n t i a l f o r p i t steepening e x i s t s i f the berm face i n the v o l c a n i c s can be maintained at a s l i g h t l y steeper angle, e.g. 70 ins t e a d of the present 66°. I t may be p o s s i b l e t o achieve t h i s g oal i f t r i m b l a s t i n g procedures are modified t o reduce b l a s t damage t o the f i n a l w a l l . i i i TABLE OF CDNTENTS Ab s t r a c t . .•' i i Table of contents i v L i s t of Appendices v i i L i s t of Tables i x L i s t of Figures x Acknowledgement x i i 1.0 I n t r o d u c t i o n 1 1.1 Terms of Reference 1 1.2 Purpose of Report 2 1.3 Scope of Work 3 2.0 S i t e C onditions 5 2.1 Location 5 2.2 Physiography 5 2.3 Surface Hydrology 5 2.4 Climate 9 3.0 Geology 10 3.1 Geologic H i s t o r y 10 3.2 P l e i s t o c e n e Geology 13 3.3 Geologic U n i t s i n the Main Zone P i t 14 3.3.1 P y r o c l a s t i c D i v i s i o n 2 14 3.3.2 Gabbro Monzonite I n t r u s i v e D i v i s i o n 6 17 3.3.3 Dykes 18 3.4 M i n e r a l i z a t i o n 20 4.0 Mining Program 22 4.1 Summary of Present Mine Plan 22 4.2 Inner P i t / Pushback 23 5.0 Main Zone S t r u c t u r a l Geology 25 5.1 Past Program 25 5.2 S t r u c t u r a l Mapping program 25 5.3 Geologic Domains 26 5.3.1 Domain Dl 31 5.3.2 Domain D2 36 5.3.3 Domain D3 42 5.3.4 Domain D4 47 i v 6.0 Groundwater Hydrology 52 6.1 Location of Test S i t e s 54 6.2 H y d r a u l i c C o n d u c t i v i t y T e s t i n g 57 6.2.1 Background 57 6.2.2 Method 58 6.2.3 R e s u l t s 59 6.3 Piezometer Monitoring 62 6.4 I n t e r p r e t a t i o n of Main Zone Hydrology 65 6.5 Surface Run-off 70 6.6 Considerations f o r P i t Dewatering 72 6.6.1 Background 72 6.6.2 S e n s i t i v i t y Study 73 6.6.2.1 H y d r a u l i c C o n d u c t i v i t y 73 6.6.2.2 A q u i f e r Thickness 75 6.6.2.3 S p e c i f i c Y i e l d 77 6.6.2.4 Pumping Rate 77 6.6.2.5 Most L i k e l y S i m u l a t i o n 80 6.7 Dewatering Systems 82 6.7.1 E x i s t i n g Sump Method 82 6.7.2 M o d i f i e d Sump Trench 83 6.7.3 P i t Perimeter Wells 83 6.7.4 I n - P i t W e l l P o i n t System 84 6.7.5 H o r i z o n t a l Drains 85 6.7.6 G r a v i t y Wells 86 6.7.7 System E v a l u a t i o n 87 6.8 Considerations f o r W a l l S t a b i l i t y 90 6.9 Recommendations f o r Further Work 95 6.9.1 Completion of P r e l i m i n a r y Study 95 6.9.2 I n i t i a l Dewatering / Pump Tests 96 6.9.3 G r a v i t y Drainage 97 7.0 Shear Strength Considerations 99 7.1 Poi n t Load T e s t i n g 100 7.2 Estimation of F r i c t i o n Angle 101 7.3 Back A n a l y s i s of Berm F a i l u r e s 103 7.4 Shear Strength Summary 107 8.0 B l a s t i n g Considerations 110 8.1 Influence of B l a s t i n g on W a l l S t a b i l i t y 110 8.2 Parameters that C o n t r o l B l a s t Performance 110 8.3 Current B l a s t i n g P r a c t i c e 113 8.4 Areas of P o t e n t i a l Improvement 114 8.4.1 Use of ANFO i n Line Holes 114 8.4.2 Reduction of Charge per Hole 115 8.4.3 - Reduction of Burden i n Line Holes 118 8.4.4 Influence of Rock Conditions 118 8.4.5 Hercudet I n i t i a t i o n System 120 8.4.6 F i r i n g Order 121 v 9.0 E v a l u a t i o n of P i t Slope S t a b i l i t y 123 9.1 Parameters that Influence S t a b i l i t y 123 9.2 Methods and Assumptions Used i n Design 125 9.3 Design Sectors 126 9.3.1 Sector S l 128 9.3.2 Sector S2 129 9.3.3 Sector S3 131 9.3.4 Sector S4 133 9.3.5 Sector S5 136 9.3.6 Sector S6 138 9.3.7 Sector S7 140 9.3.8 Sector S8 142 9.3.9 Sector S9 144 9.3.10 Sector S10 146 10.0 Monitoring 148 10.1 L e v e l 1 Monitoring ( F a i l u r e Detection) 148 10.2 L e v e l 2 Monitoring ( F a i l u r e Evaluation) 150 10.3 L e v e l 3 Monitoring (Mine and Monitor) 153 11.0 Continuing Program 158 11.1 D i s c o n t i n u i t i e s 158 11.2 Groundwater 159 11.3 Shear Strength Parameters 159 11.4 Trim B l a s t i n g 161 11.5 Monitoring 162 12.0 Summary & Conclusions 163 13.0 B i b l i o g r a p h y 167 v i APPENDICES Appendix A STRUCTURAL DATA 168 A . l S t r u c t u r a l Domain 1 Summary and Stereonets 168 A.2 S t r u c t u r a l Domain 2 Summary and Stereonets 177 A.3 S t r u c t u r a l Domain 3 Summary and Stereonets 186 A. 4 S t r u c t u r a l Domain 4 Summary and Stereonets 195 Appendix B PROGRAM SWEDGE 204 B. 1 O b j e c t i v e 204 B.2 Theory 204 B.3 L i s t of V a r i a b l e s 109 B.4 Flow Chart 211 B.5 Procedure f o r Use 215 B.6 Program Code 217 Appendix C BACK ANALYSIS DATA 223 C l F i e l d Record Forms and R e s u l t s of C a l c u l a t i o n s 223 Appendix D HARDNESS CHARTS 251 Appendix E THEORY OF FALLING HEAD TESTS 252 Appendix F PROGRAM EQFHEAD 256 F . l Purpose 256 F.2 Theory 256 F.3 Flow Chart 257 F.4 L i s t of V a r i a b l e s 258 F.5 Procedure f o r Use 259 F. 6 Program Code 260 Appendix G TESTING APPARATUS 262 G. l Equipment L i s t 262 G.2 Equipment Set Up 263 G. 3 Test i n g Procedure 266 Appendix H F a l l i n g Head Test Records 267 H. l F i e l d Record Forms 267 H.2 C a l c u l a t i o n s 280 H.3 Previous R e s u l t s 294 H. 4 Blank F i e l d Record Sheet 297 Appendix I PROGRAM EQDRAWDN 298 I. 1 Purpose 298 1.2 Theory of Si m u l a t i n g Pumping W e l l Drawdown 299 1.3 Flow Chart 302 1.4 L i s t of V a r i a b l e s 305 1.5 Procedure f o r Use 306 1.6 Program Code 307 v i i Appendix J PIEZOMETERS 310 J . l Piezometer I n s t a l l a t i o n 310 J.2 Piezometer Location 312 J.3 Monitoring Records 313 Appendix K RESULTS OF PUMPING WELL SIMULATION 314 K . l Influence of K 314 K.2 Influence of Thickness 318 K.3 Influence of S p e c i f i c Y i e l d 322 K.4 Influence of Pumping Rate 326 K.5 Sim u l a t i o n of Expected C o n d i t i o n 332 Appendix PLAN ENVELOPE 3^3" Plan 1 - P i t Geology 3p4 Plan 2 - S t r u c t u r a l Geology 335 Plan 3 - Traverse Locations - Instrumentation 336 Plan 4 - Main Zone Design Sectors 3'3,7 Plan 5 - Main Zone Ultimate P i t 3 % ALL 'it) v i i i LIST OF TABLES 3.1 Table of Geologic Ages 10 4.1 Summary of p i t Wall Angles 23 5.1 Symbols and Codes Used i n Stereonets 28 5.2 O r i e n t a t i o n s of Major S t r u c t u r e s D-l 32 5.3 O r i e n t a t i o n s of Major S t r u c t u r e s by Type D-l 32 5.4 F a i l u r e Modes D-l 34 5.5 O r i e n t a t i o n s of Major S t r u c t u r e s D-2 37 5.6 O r i e n t a t i o n s of Major S t r u c t u r e s by Type D-2 39 5.7 F a i l u r e Modes D-2 39 5.8 O r i e n t a t i o n s of Major S t r u c t u r e s D-3 44 5.9 O r i e n t a t i o n s of Major S t r u c t u r e s by Type D-3 44 5.10 F a i l u r e Modes D-3 45 5.11 O r i e n t a t i o n s of Major S t r u c t u r e s D-4 49 5.12 O r i e n t a t i o n s of Major S t r u c t u r e s by Type D-4 49 5.13 F a i l u r e Modes D-4 50 6.1 Levels of Hy d r a u l i c C o n d u c t i v i t y Required f o r Dewatering . 57 6.2 R e s u l t s of F a l l i n g Head P e r m e a b i l i t y Tests 59 6.3 Representative Values of H y d r a u l i c C o n d u c t i v i t y 60 6.4 Normal Range of P e r m e a b i l i t i e s i n S o i l and Rock 61 7.1 Po i n t Load Index Strength Summary 100 8.1 Table of Constants f o r B l a s t Damage Formula 116 9.1 Summary of Design Parameters 127 i x LIST OF FIGURES 2.1 L o c a t i o n of Equity S i l v e r Mines 6 2.2 L o c a t i o n of Creeks and D i v e r s i o n Channels 8 3.1 Property Geology 12 3.2 Photograph Showing How Gabbro Breaks on Continuous J o i n t s . 18 3.3 Photograph Showing Thick Andesite Dyke 21 5.0 Common F a i l u r e Modes i n Open P i t s 30 5.1 Major S t r u c t u r e s Stereonet D-l 33 5.2 A l l Major S t r u c t u r e s Stereonet D-l 33 5.3 Poles t o Major S t r u c t u r e s by Type D-l .- 35 5.4 F a i l u r e Modes D-l 35 5.5 Major S t r u c t u r e s Stereonet D-2 38 5.6 A l l Major S t r u c t u r e s Stereonet D-2 38 5.7 Poles t o Major S t r u c t u r e s by Type D-2 41 5.8 F a i l u r e Modes D-2 41 5.9 Major S t r u c t u r e s Stereonet D-3 43 5.10 A l l Major S t r u c t u r e s Stereonet D-3 43 5.11 Poles t o Major S t r u c t u r e s by Type D-3 46 5.12 F a i l u r e Modes D-3 46 5.13 Major S t r u c t u r e s Stereonet D-4 48 5.14 A l l Major S t r u c t u r e s Stereonet D-4 48 5.15 Poles t o Major S t r u c t u r e s by Type D-4 51 5.16 F a i l u r e Modes D-4 51 6.1 Piezometer Location P l a n 55 6.2 Piezometer Monitoring 63 6.3 Watershed Recharging Main Zone P i t 66 6.4 Main Zone Flownet 66 6.5 Groundwater Flow Paths 67 6.6 Hydrologic Influence of Gabbro Tongue 69 6.7 Run-off C o n t r o l 71 6.8 Influence of H y d r a u l i c C o n d u c t i v i t y on Dewatering 74 6.9 Influence of A q u i f e r Thickness on Dewatering 76 6.10 Influence of S p e c i f i c Y i e l d on Dewatering 78 6.11 Influence of Pumping Rate on Dewatering 79 6.12 Expected Drawdown C o n d i t i o n 81 6.13 WIP/GraD System of P i t Dewatering 89 6.14 H y p o t h e t i c a l Plane F a i l u r e Showing Influence of Water 91 6.15 Influence of Groundwater on Slope S t a b i l i t y 93 7.1 Determination of Approximate Basic F r i c t i o n Angle 101 7.2 Cohesion and F r i c t i o n Angle f o r Dry Slope A n a l y s i s 105 7.3 Cohesion and F r i c t i o n Angle f o r Wet Slope A n a l y s i s 105 7.4 P r o b a b i l i t y Function f o r C and 0 at L i m i t i n g E q u i l i b r i u m . 107 8.1 Mechanics of Trim B l a s t I l l 8.2 Present Trim B l a s t P a t t e r n 113 8.3 Graph of Depth of Damaged Rock vs. E x p l o s i v e Charge 117 8.4.A Present Detonation Sequence 122 8.4.B Detonation Sequence f o r Free Face Perpendicular t o Wall .. 122 x 9.1 Main Zone Design Sectors , 127 9.2 Stereonet f o t Design Sector S - l 130 9.3 Stereonet f o r Design Sector s-2 130 9.4 Stereonet f o r Design Sector S-3 132 9.5 Stereonet f o r Design Sector S-4 134 9.6 S t a t i s t i c a l D i s t r i b u t i o n of Dip on Group A Planes 134 9.7 Stereonet f o r Design Sector S-5 137 9.8 Stereonet f o r Design Sector S-6 139 9.9 Stereonet f o r Design Sector S-7 141 9.10 Stereonet f o r Design Sector S-8 143 9.11 Stereonet f o r Design Sector S-9 145 9.12 Stereonet f o r Design Sector S-10 147 10.1 Tension Crack Displacement Monitoring Tool 151 10.2 Components of L e v e l 2 Monitoring Program 153 10.3 P l o t of D a i l y Displacement of Large S l i d e 154 10.4 P l o t of Cummulative Displacement of Large S l i d e 154 x i ACKNOWLEDGEMENT I wish t o thank Professor CO. Brawner for h i s support i n a l l phases of t h i s t h e s i s . H is continued i n t e r e s t and p a r t i c i p a t i o n from the e a r l y f i e l d work t o c r y t i c a l reviews of the t h e s i s d r a f t s i s g r a t e f u l l y appreciated. S p e c i a l thanks are due t o Equity S i l v e r Mines L t d . f o r t h e i r e n t h u s i a s t i c cooperation and f i n a n c i a l support of t h i s p r o j e c t ; i n p a r t i c u l a r , Mr. Doug Fraser who permitted the author t o use a l l i n f o r m a t i o n obtained during the 1984 g e o t e c h n i c a l i n v e s t i g a t i o n i n t h i s t h e s i s , and Mr. Bob Baase who made a v a i l a b l e a l l resources of the Mine Engineering Department. I wish t o express s i n c e r e a p p r e c i a t i o n t o Mr. Jack M i l l e r f o r h i s a s s i s t a n c e , guidance, and i n s p i r a t i o n while the author was working at the mine and e s p e c i a l l y f o r h i s c r i t i c a l readings of the manuscript. I g r a t e f u l l y acknowledge Mr. peter Beaudoin's help with the workings of Equity's computing f a c i l i t i e s and the numerous d i s c u s s i o n s on the p r i n c i p l e s of p i t design. The t h e s i s was p a r t i a l l y funded by the B r i t i s h Columbia Science C o u n c i l . This a s s i s t a n c e was very appreciated. F i n a n c i a l support r e c e i v e d from the Cy and Emerald Keys Memorial S c h o l a r s h i p was a l s o accepted w i t h warm thanks. F i n a l l y , I wish t o thank the s t a f f at Equity S i l v e r Mines L t d . who e n t h u s i a s t i c a l l y provided a s s i s t a n c e whenever re q u i r e d and who took an a c t i v e i n t e r e s t i n the p r o j e c t . Without t h e i r continued support t h i s t h e s i s c o u l d not have been completed. x i i 1.0 INTRODUCTION This report presents the f i n d i n g s of a g e o t e c h n i c a l study c a r r i e d out i n the summer of 1984 i n the Main zone p i t at Equity S i l v e r Mines. The i n v e s t i g a t i o n had f i v e g o a l s : 1. To design o v e r a l l slope angles i n the Main Zone p i t . 2. To evaluate the i n f l u e n c e of s t r u c t u r a l geology, groundwater, shear s t r e n g t h , and monitoring on s t a b i l i t y . 3. To study the e x i s t i n g groundwater c o n d i t i o n s i n the Main Zone p i t i n order t o determine whether p i t dewatering w i l l be p o s s i b l e . 4. To introduce a m u l t i - s t a g e monitoring program f o r the Main Zone p i t that w i l l ensure e a r l y d e t e c t i o n of any i n s t a b i l i t i e s and adequate monitoring of the rat e s of movement once the s l i d e s are i d e n t i f i e d . 5. To recommend operating procedures i n the areas of b l a s t i n g , dewatering, and monitoring that w i l l improve s t a b i l i t y i n the Main zone p i t , make i t s a f e r , and p o s s i b l y a l l o w f o r f u r t h e r increase i n p i t w a l l angle. 1.1 TERMS OF REFERENCE The g e o t e c h n i c a l study summarized i n t h i s report was a j o i n t e f f o r t c a r r i e d out by the Mine Engineering Department at Equity S i l v e r Mines and The Department of Mining and M i n e r a l Process, Engineering at The U n i v e r s i t y of B r i t i s h Columbia. A p r e l i m i n a r y s t r u c t u r a l s t a b i l i t y a n a l y s i s was c a r r i e d out by Equity engineers i n 1983. The study concluded that there was p o t e n t i a l f o r steepening s e c t i o n s of the p i t , but f u r t h e r i n v e s t i g a t i o n was r e q u i r e d t o confirm the observed trends. P r o f . CO. Brawner of the Department of Mining and M i n e r a l Process Engineering submitted a proposal t o have a graduate student a s s i s t the Mine Engineering Department i n the advanced stage of the ge o t e c h n i c a l i n v e s t i g a t i o n . This proposal was accepted. 1 F i e l d work i n a l l areas of the ge o t e c h n i c a l i n v e s t i g a t i o n was c a r r i e d out during the summer of 1984, e a r l y May t o mid-September, by the author and Equity Mine Engineering personnel. Progress was reviewed on a p e r i o d i c b a s i s by Professor Brawner. A n a l y s i s of data was c a r r i e d out i n part during the sunnier at Equity; most of the design work was completed at The U n i v e r s i t y of B.C. This t h e s i s summarizes the f i n d i n g s of the geo t e c h n i c a l s t u d i e s . 1.2 PURPOSE OF REPORT The purpose of t h i s t h e s i s i s t o present the f i n d i n g s of the geo t e c h n i c a l i n v e s t i g a t i o n s c a r r i e d out i n the Main Zone p i t during the summer of 1984. The most important g o a l of the program was t o design u l t i m a t e p i t w a l l angles according t o the geol o g i c s t r u c t u r e observed i n each design s e c t o r i n the Main Zone. Procedures used t o develop the p i t w a l l design are a l s o presented. The second o b j e c t i v e o f the report i s t o present the r e s u l t s of the hy d r o l o g i c i n v e s t i g a t i o n . The purpose of the hydrology study was t o determine the e x i s t i n g groundwater c o n d i t i o n s i n the Main Zone and t o f i n d out whether the Main zone p i t c o u l d be s u c c e s s f u l l y dewatered. The h y d r o l o g i c s e c t i o n of t h i s t h e s i s a l s o reviews e x i s t i n g dewatering technology and makes recommendations as t o which systems could be the most e f f e c t i v e i n dewatering the Main Zone p i t . 2 The t h i r d o b j e c t i v e of the t h e s i s i s t o summarize the r e s u l t s of the shear s t r e n g t h t e s t i n g program. Representative magnitudes of shear s t r e n g t h parameters are req u i r e d i n the s t a b i l i t y e v a l u a t i o n of any k i n e m a t i c a l l y p o s s i b l e wedges and i n the design of support systems. Many methods of improving slope s t a b i l i t y have been developed i n recent y e a r s , e s p e c i a l l y i n the area of c o n t r o l b l a s t i n g . Several c o n t r o l b l a s t i n g procedures t h a t have p o t e n t i a l f o r improving s t a b i l i t y i n the Main Zone p i t , that appear p r a c t i c a l , and that should be of economic b e n e f i t t o the operation are introduced. Monitoring t o detect p i t w a l l movement i s an important part of an o v e r a l l open p i t s t a b i l i t y program. This report reviews e x i s t i n g technology and o u t l i n e s monitoring procedures that should be implemented i n the Main Zone p i t t o ensure r a p i d d e t e c t i o n of any i n s t a b i l i t i e s . 1.3 SCOPE OF WORK The g e o t e c h n i c a l i n v e s t i g a t i o n that was c a r r i e d out t o develop the p i t w a l l design and t o evaluate the p o t e n t i a l f o r Main zone p i t dewatering c o n s i s t e d o f : 1 - STRUCTURAL GEOLOGY - l i n e mapping of exposed i n t e r i o r and u l t i m a t e p i t w a l l s - s t r u c t u r a l d r i l l hole logging and core o r i e n t a t i o n - a n a l y s i s of s t r u c t u r a l data using Discodat System - d e s i g n a t i o n of s t r u c t u r a l domains 2 - SHEAR STRENGTH - p o i n t load t e s t i n g of d r i l l core - s l i p t e s t s f o r 0 - back a n a l y s i s of sm a l l wedge f a i l u r e s - assessment of shear s t r e n g t h parameters 3 3 - GROUNDWATER HYDROLOGY - f i e l d reconnaissance - weekly piezometer monitoring - completion of 1 1 piezometers - f a l l i n g head p e r m e a b i l i t y t e s t s - assessment of groundwater hydrology i n the Main Zone - computer modelling of dewatering systems - e v a l u a t i o n of dewatering systems 4 - BLASTING - e v a l u a t i o n of Equity's t r i m b l a s t i n g program 5 - PIT WALL DESIGN - s e l e c t i o n of design s e c t o r s - assessment of s t a b i l i t y i n each sect o r - design of slope angle i n each sect o r 6 - MONITORING - development of g u i d e l i n e s f o r a slope s t a b i l i t y monitoring program With the exception of the diamond d r i l l i n g phase of the program th a t was completed by J.T. Thomas L t d ; a l l d r i l l i n g , i nstrumentation i n s t a l l a t i o n , and t e s t i n g was c a r r i e d out by Equity Mine Department personnel. 4 2.0 SITE CONDITIONS 2.1 LOCATION Equ i t y S i l v e r Mine i s l o c a t e d i n c e n t r a l B r i t i s h Columbia, 54*12' N l a t i t u d e and 126°16' W lo n g i t u d e . I t i s s i t u a t e d i n the uplands of the Nechako P l a t e a u , 35 km southeast of Houston, the nearest town. Access t o the mine s i t e i s by a 37 km a l l weather, g r a v e l surface road from Houston t h a t f o l l o w s the Dungate Creek drainage. Figure 2.1 shows the l o c a t i o n of the mine s i t e on p r o v i n c i a l and r e g i o n a l maps. 2.2 PHYSIOGRAPHY Topography at Equity c o n s i s t s of r o l l i n g h i l l s and broad v a l l e y s . E l e v a t i o n changes are f o r the most pa r t gradual as topography has been subdued and rounded by t e r t i a r y l a v a flows that flowed i n near h o r i z o n t a l sheets, f i l l i n g e x i s t i n g topographic lows, and p l e i s t o c e n e g l a c i a t i o n that has rounded the h i l l tops and deposited a t h i c k blanket of g l a c i a l t i l l and g l a c i o f l u v i a l d e p o s i t s i n much of the lowland. R e l i e f i n the immediate area i s approximately 725 m, from a low of 900 m at Goosly Lake (5 km southwest of the mine) t o a high of 1625 m at a prominent r i d g e top 3 km east of the Main Zone p i t . This topographic high i s formed by rocks of the gabbro monzonite i n t r u s i v e complex t h a t are r e l a t i v e l y r e s i s t a n t t o e r o s i o n . The gabbro intruded i n t o the o v e r l y i n g v o l c a n i c s some 48 m i l l i o n years ago. 5 Figure 2.1 LOCATION OF EQUITY SILVER MINES 6 2.3 SURFACE HYDROLOGY The major drainage systems t h a t d r a i n the Nechako Plateau i n the area of Equity e x h i b i t a northwest - southeast l i n e a t i o n (e.g. Buck, P a r r o t , Maxan, and Owen Creeks). The t r i b u t a r y drainage p a t t e r n between these creeks i s d e n d r i t i c . S everal surface water catchments d r a i n the mine property: 1) Lu Creek d r a i n s the f l a t s west of the mine f a c i l i t i e s , 2) Foxy Creek c o l l e c t s runoff from a low r e l i e f b a sin north of the mine, 3) B e r z e l i u s Creek flows from the highlands northeast of the p i t , and 4) Bessemer Creek drainage covers most of the h i l l s i d e east of the Main Zone p i t . L o c a t i o n of the above creeks and d i v e r s i o n channels i s i l l u s t r a t e d i n r e l a t i o n t o the mine f a c i l i t i e s i n Figure 2.2. Water i s an important f a c t o r i n the s t a b i l i t y of the Main Zone p i t ; t h e r e f o r e , i t i s important t o have a good understanding of the l o c a t i o n of catchment basins and groundwater recharge areas i n the immediate v i c i n i t y . The l a r g e s t source area f o r groundwater seepage and surface runoff i n t o the p i t i s the Bessemer Creek drainage. The o r i g i n a l stream bed foll o w e d a wes t e r l y course through the center of the Main Zone ore body and then turned sha r p l y south, e v e n t u a l l y emptying i n t o Buck Creek above Goosly Lake. The creek has s i n c e been d i v e r t e d northward by a d i v e r s i o n d i t c h that a l s o c o l l e c t s s u r f a c e water from B e r z e l i u s Creek. The upper Bessemer catchment b a s i n covers an area of 3 km. Most water th a t i n f i l t r a t e s i n t o the groundwater system i n the basin w i l l e v e n t u a l l y discharge i n t o the p i t . Some groundwater seepage w i l l a l s o o r i g i n a t e i n the B e r z e l i u s Creek and Lu Creek catchments. However, i n f l o w s are expected t o be s m a l l because the recharge areas are much 7 SCALE I • 50,000 LEGEND 1 o O CREEK. DIVERSION DITCH BOUNDARY OF MAIN ZONE PIT GROUNDWATER RECHARGE AREA OPEN PIT WASTE DUMP TAILINGS DAM Figure 2.2 LOCATION OF CREEKS AND DIVERSION CHANNELS 8 s m a l l e r , and f o r the most p a r t , covered w i t h a blanket of low p e r m e a b i l i t y g l a c i a l t i l l . The t i l l promotes surface r u n o f f . 2.4 CLIMATE Climate at the mine s i t e i s i n f l u e n c e d by the high e l e v a t i o n and p r o x i m i t y t o the P a c i f i c west coast. Temperatures average about 13 C during the summer months and about -12 C during the winter. The property r e c e i v e s an average of 51 cm of p r e c i p i t a t i o n annually. Most p r e c i p i t a t i o n s t a t i s t i c a l l y f a l l s during the winter months, but the past s e v e r a l summers have been abnormally c o o l and wet. Annual s n o w f a l l exceeds 2 m; with much of the property remaining snow covered u n t i l mid-June. 9 GEOLOGY The Equity Ag-Cu deposit i s s i t u a t e d i n an i n l i e r of Cretaceous (65-71 m.y.) v o l c a n i c and sedimentary rocks c a l l e d the Goosly Sequence. Rocks of t h i s sequence are exposed at surface only i n the area around the E q u ity Property. Outside the i n l i e r , they are covered by T e r t i a r y v o l c a n i c f l o w s . The contact between the Goosly Sequence and the T e r t i a r y flows i s unconformable; the Goosly Sequence was t i l t e d before the near h o r i z o n t a l l a v a flows covered the landscape. Two i n t r u s i o n s are a l s o present w i t h i n the i n l i e r : 1) A quartz-monzonite stock i s s i t u a t e d 1 km west of the Main zone ore body, and 2) a gabbro-monzonite complex has intruded j u s t east of the ore zone, the contact forms the the f o o t w a l l of the of the ore body. 3.1 GEOLOGIC HISTORY The geology at the Equity Property has been d i v i d e d i n t o 7 u n i t s by s i t e g e o l o g i s t s (Pease et a l . 1983). These u n i t s are summarized below. Table 3.1. R e l a t i v e Age Per i o d U n i t Name youngest T e r t i a r y 7 A n d e s i t i c Flows & Flow Bre c c i a s II 6 Gabbro Monzonite I n t r u s i v e n 5 Quartz Monzonite I n t r u s i v e Cretaceous 4 V o l c a n i c Flow D i v i s i o n n 3 Sedimentary V o l c a n i c D i v i s i o n n 2 P y r o c l a s t i c D i v i s i o n o l d e s t n 1 C l a s t i c D i v i s i o n The o l d e s t rocks on the property are the C l a s t i c D i v i s i o n , a t r a n s g r e s s i v e s e r i e s of conglomerate, sandstone, and a r g i l l i t e that were deposited i n a subaqeous environment. 10 V i o l e n t v o l c a n i c a c t i v i t y n orth of the mine then generated vast q u a n t i t i e s of p y r o c l a s t i c m a t e r i a l that accumulated over time t o cover the area w i t h as much as 975 m of ash and coarser e j e c t a . M a t e r i a l of Unit 2 i s coarser i n the north p o r t i o n of the property ( i . e . the Main Zone). There, the dominant l i t h o l o g y i s l a p i l l i t u f f ( t u f f t h a t has fragments 4-32 mm i n diameter) with minor zones of v o l c a n i c b r e c c i a and dust t u f f . To the south, U n i t 2 becomes much f i n e r grained; dust t u f f i s the dominant rock type i n the Southern T a i l p i t . A f t e r the major eruptions a d d i t i o n a l ash and coarser v o l c a n i c rock were t r a n s p o r t e d i n t o the area by f l u v i a l and mass wasting processes t o deposit Unit 3, the Sedimentary-Volcanic D i v i s i o n . Another episode of v o l c a n i c a c t i v i t y covered the area w i t h l a v a flows of A n d e s i t i c t o D a c i t i c composition. This was the l a s t event i n the formation of the Goosly Sequence. Tectonic a c t i v i t y then continued w i t h the i n t r u s i o n of the Quartz-Monzonite Stock approximately 60 m i l l i o n years ago and the emplacement of the Gabbro-Monzonite Complex 48-49 m i l l i o n years ago (ages based on data of s e v e r a l workers summarized by Pease et a l . 1983). The Goosly Sequence was t i l t e d during t h i s p e r i o d t o i t s present o r i e n t a t i o n of: s t r i k e 015°, d i p 45°- 80° W. A n d e s i t i c l a v a flows covered much of the low l y i n g areas i n the f i n a l d e p o s i t i o n a l event s h o r t l y a f t e r i n t r u s i o n of the Gabbro Complex. Church (1970), suggests t h a t t h i s i n t r u s i v e was the feeder f o r the fl o w s , c i t i n g m i n e r a l o g i c a l and chemical s i m i l a r i t i e s between u n i t s as evidence. A g e o l o g i c map of the Equity Property (Figure 3.1) shows the l o c a t i o n of the 7 l i t h o l o g i c u n i t s . 11 LITHOSTRATIGRAPHIC LEGEND PERIOD UNIT LITHOLOGY Tertiary C r e t a c e o u s • • • • • A n d e s i t i c F l o w s a n d F l o w B r e c c i a s G a b b r o - M o n z o n i t e I n t r u s i v e C o m p l e x Q u a r t z - M o n z o n i t a S t o c k |2A - V o l c a n i c Flow D i v i s i o n D a c i t a & A n d a s l t a Flows - S e d i m e n t a r y V o l c a n i c D i v i s i o n V o l c a n i c Sandstone a n d Conglomerate, Tuff « P y r o c l o i t l c D i v i s i o n Lap! I l l and A s h T u f f 23 I Dust T u f f • S C A L E I • 5 0 , 0 0 0 - C l a s t i c D i v i s i o n Conglomerate Minor S a n d s t o n e a Sllfstone A r g i l l i f e 2 km Figure 3.1 PROPERTY GEOLOGY - EQUITY SILVER MINE ( Modified after Pease, 1983 ) 3.2 PLEISTOCENE GEOLOGY Much of the Equity property i s covered w i t h g l a c i a l t i l l t h at was deposited during the l a s t major g l a c i a l advance of the l a t e p l e i s t o c e n e , approximately 10,000 years ago. During the e a r l i e s t p e r i o d of the Fraser g l a c i a t i o n a l p i n e g l a c i e r s grew, e v e n t u a l l y c o a l e s c i n g t o form a c o n t i n e n t a l i c e sheet. During the climax of the g l a c i a t i o n r e g i o n a l i c e movement was t o the northeast. The f l o w i n g i c e scoured the bedrock, p l u c k i n g up any loose fragments. Evidence of the n o r t h e a s t e r l y f l o w can be observed on s t r i a t e d s u r faces of s e v e r a l outcrops i n the v i c i n i t y of the mine. Topographic highs were rounded by the e r o s i v e f o r c e s of the f l o w i n g i c e of s e v e r a l g l a c i a t i o n s . Rock th a t was plucked up was then c a r r i e d along w i t h the i c e , much of i t broken down t o g l a c i a l f l o u r . The reworked m a t e r i a l was deposited as ground moraine at the bottom of the g l a c i e r and h i g h l y compacted by the weight of the o v e r l y i n g i c e . The t h i c k e s t d e p o s i t s of g l a c i a l t i l l occur i n topographic lows. In one d r i l l hole on the property 45 m of t i l l were t r i c o n e d before bedrock was encountered (We t h e r e l l , 1979); however, the normal t h i c k n e s s of t i l l ranges from 10 t o 20 m i n the v a l l e y s and 0 t o 5 m at higher e l e v a t i o n s . Composition of the t i l l i s u s u a l l y s i l t y c l a y with t r a c e t o some g r a v e l , but can vary from l o c a t i o n t o l o c a t i o n . Because the t i l l has a very high c l a y content and i s w e l l compacted i t i s very impermeable. As a r e s u l t , i n t i l l covered areas most p r e c i p i t a t i o n d r a i n s as surface runoff before i t can seep i n t o the groundwater system. The t i l l blanket a l s o c o n f i n e s s e v e r a l u n d e r l y i n g a q u i f e r s of f l u v i a l sands and f r a c t u r e d 13 bedrock. Artesian conditions have been observed in several boreholes on the property where the confined aquifers are located in steep terrain. Hydrologic investigations by Golder Associates (1983) have confirmed the presence of f l u v i a l l y deposited sands and gravels below the t i l l in the lower reaches of Lu and Bessemer Creeks. The sands and gravels are the bed load of pre-glacial streams that were burried by the advancing glaciers. In the fi n a l stages of the Fraser glaciation the direction of ice movement reversed because local topography again began to influence the flow direction of the much shrunken ice sheet. Evidence indicating this f i n a l episode of southwest movement includes: 1) southwesterly offsets in the Ag geochemical anomaly over the ore zones, 2) southwest transport of a granitic boulder train from a well defined source area, and 3) roches moutonnees structures with g l a c i a l striae that clearly indicate a flow direction of 240° (Wojdak, 1974 & Wetherell 1979). 3.3 GEOLOGIC UNITS IN THE MAIN ZONE Only two of the seven geologic units occur in the Main Zone. Pyroclastic Division 2A is the host rock for the economic mineralization, and the gabbro-monzonite intrusive complex (Division 6) w i l l form much of the east ultimate pit wall. The gabbro is also being actively mined for non-acid generating r o c k f i l l that i s used in the construction of the tailings dams. Rocktype influences virtually a l l aspects of pit design and mining operations. Therefore, i t i s important to have a good understanding of the physical properties and characteristics of the rockmass. 14 3.3.1 Pyroclastic Division 2A The dominant rock type in the pyroclastic unit is l a p i l l i tuff. The l a p i l l i fragments are usually subangular to subrounded and composed of aphanitic groundmass. The matrix is finer grained ash. Colour of the l a p i l l i tuff i s dark grey but can deviate to a dark olive green i f chlorite alteration is present. The hardness classification ranges between R3 to R4, depending on degree of alteration. Point load tests were also carried out on the d r i l l core to determine the uniaxial compressive strength. Results of these tests are discussed in Section 7.1. The l a p i l l i tuff, with an average uniaxial compressive strength of 112 MPa is cl a s s i f i e d as "strong rock"* Joint set spacings of 0. 2 to 0.6 m (DISCODAT classification i) were observed most often in line mapping of p i t walls. Most joints were not continuous (i.e. less than 5 m in length). Other rock types that are present in Unit 2A include flow breccia, ash tuff, dust tuff, and minor volcanic conglomerate. The breccia has rockmass characteristics that are very similar to those of the l a p i l l i tuff except that the clasts are angular and often larger in size. The ash tuff occurs in irregular zones within the l a p i l l i , the contacts are generally gradational. Ash tuff i s defined as a pyroclastic rock with grains smaller than 4 mm in diameter, but sufficiently large to be visible to the naked eye. Colour of the ash tuff is also dark grey to olive green. Hardness classification i s 1. Based on classification system proposed by Hoek, 1981 that is lis t e d in Appendix D.l. 15 u s u a l l y R3. U n i a x i a l strengths obtained from the p o i n t load t e s t s were approximately 30% lower than f o r the l a p i l l i , averaging 88 Mpa, or "moderately strong rock". J o i n t i n g i s a l s o more common i n the ash t u f f than i n the l a p i l l i . Dust t u f f i s rare i n the Main Zone p i t . When i t does occur i t seems t o be i n l o c a l i z e d lenses t h a t span l e s s than 100 m i n the longest dimension. The rocktype can be i d e n t i f i e d e a s i l y i n hand specimens because i t i s a p h a n i t i c ( i n d i v i d u a l g r a i n s too f i n e t o be d i s t i n g u i s h e d by the naked eye). Colour i s u s u a l l y a l i g h t e r shade of grey. In the p i t w a l l , zones of dust t u f f can be recognized by the blocky, crumbling nature of the p i t w a l l . This c h a r a c t e r i s t i c i s caused by very c l o s e l y spaced, i n t e r s e c t i n g s e t s of j o i n t s . The j o i n t s are once again d i s c o n t i n u o u s . Some of the j o i n t s observed at surface may a c t u a l l y be f r a c t u r e s opened up by b l a s t i n g because the rock i s moderately weak (R3) and b r i t t l e . I t i s t h e r e f o r e s u s c e p t i b l e t o b l a s t damage. However, d i s c o n t i n u i t i e s were a l s o much more prevalent i n dust t u f f d r i l l core from s t r u c t u r a l d r i l l hole DDH 84-167 t h a t was not damaged by b l a s t i n g than core of the other rock types. U n i a x i a l compressive s t r e n g t h was about 44 mPa and rock q u a l i t y d e s i g n a t i o n i n d i c e s (RQD) o f t e n dropped below 50 percent i n the dust t u f f . In summary, engineering p r o p e r t i e s of the i n t a c t p y r o c l a s t i c rocks are r e l a t e d t o g r a i n s i z e . Strength decreases and degree of j o i n t i n g i ncreases w i t h decreasing g r a i n s i z e . O v e r a l l , p y r o c l a s t i c u n i t 2A i s s u f f i c i e n t l y competent and i n t a c t t h a t f a i l u r e s w i l l be c o n t r o l l e d by throughgoing d i s c o n t i n u i t i e s , not by exceeding the shear s t r e n g t h of the i n t a c t rock. 16 3.3.2 Gabbro Monzonite I n t r u s i v e - D i v i s i o n 6 The gabbro-monzonite i n t r u s i v e complex i s s i t u a t e d j u s t east of the Main Zone ore body. The i n t r u s i v e - v o l c a n i c contact d i p s westward, i n t o the p i t , at 40°to 45°. The i n t r u s i v e complex covers an extensive area of uplands. D e t a i l e d petrographic work by Ney et a l . (1972) has i d e n t i f i e d s i x separate i n t r u s i v e phases. A l l of the i n t r u s i v e rocks i n the eastern s e c t i o n of the Main Zone p i t c o n s i s t of phase 6C, monzonite. Monzonite i s an i n t r u s i v e rock composed p r i m a r l y of p l a g i o c l a s e and potassium f e l d s p a r , w i t h minor amounts of q u a r t z , b i o t i t e , and other common accessory minerals. In the Main Zone the monzonite i s coarse g r a i n e d , some f e l d s p a r phenocrysts exceed 1 cm i n s i z e . Colour i s medium speckled grey. I n t r u s i v e rocks are g e n e r a l l y very strong because t h e i r g r a i n s are a l l i n t e r l o c k i n g and no planes of weakness ( i . e . sedimentary bedding or metamorphic f o l i a t i o n ) are present when the rock forms. The average u n i a x i a l compressive s t r e n g t h of the gabbro-monzonite was 455 MPa, a "very strong rock". In f i e l d mapping the rock type was assigned an R5 r a t i n g , as numerous blows with a rock hammer were r e q u i r e d t o break a sample. D i s c o n t i n u i t i e s were widely spaced i n the gabbro , spacings u s u a l l y ranged from 0.6 t o 6.0 m (DISCODAT codes j and k ) . Many of the j o i n t s i were very continuous i n the gabbro, exceeding the length of double benches ( i . e . longer than 20 m). 2. The group of i n t r u s i v e rocks of D i v i s i o n 6 are g e n e r a l l y r e f e r r e d t o as "Gabbro" at the mine s i t e ; t h e r e f o r e , t h i s name w i l l be used i n the remainder of the r e p o r t . 17 When mined along the east wall of the Main Zone p i t , the gabbro has a tendency to break along a set of continuous joints that dip 50°to 55° into the p i t . This trend i s c l e a r l y seen i n Figure 3.2. Figure 3.2 PHOTOGRAPH SHOWING TENDENCY OF GABBRO TO BREAK ALONG CONTINUOUS WEST DIPPING JOINTS. 3.3.3 DYKES Dykes are common i n the Main Zone p i t . Three p r i n c i p a l types have been recognized: 1) andesite, 2) quartz l a t i t e , and 3) trachytic andesite. 18 1. Andesite dykes are the most common v a r i e t y i n the Main Zone. They are dark green t o black i n c o l o u r , a p h a n i t i c , and o c c a s i o n a l l y v e s i c u l a r . I n t a c t andesite dyke i s rated "strong" (R4, u n i a x i a l compressive s t r e n g t h of 176 MPa), but c o n s i d e r a b l y weaker specimens of a l t e r e d dyke m a t e r i a l have been t e s t e d . O r i e n t a t i o n s vary, but two trends have been recognized on the g e o l o g i c p l a n of the Main Zone p i t (Plan 1, l o c a t e d envelope): 1) a southeast s t r i k e d i p p i n g 50-60°to the southwest i s prev a l e n t i n the c e n t r a l p o r t i o n of the east w a l l , and 2) an e a s t e r l y s t r i k e d i p p i n g 70-90°to the south. Most andesite dykes are r e l a t i v e l y t h i n (0.5-2.0 m). Despite being narrow, they are very continuous and can be t r a c e d over s e v e r a l benches i n the p i t . Random j o i n t i n g i s always present, o f t e n c l o s e l y spaced. The j o i n t s are discontinuous and are best d e s c r i b e d as conchoidal (rounded f r a c t u r e s , s i m i l a r t o f r a c t u r e s i n broken g l a s s ) . 2. Quartz l a t i t e dykes are l e s s common i n the p i t , but are very prominent because of t h e i r cream c o l o u r and co n s i d e r a b l e t h i c k n e s s . Two l a t i t e dykes i n the c e n t r a l p o r t i o n of the east w a l l exceed 5 m i n t h i c k n e s s . The remaining dykes are t h i n n e r , (1-3 m). I n s u f f i c i e n t dykes e x i s t t o i d e n t i f y any s t r u c t u r a l t r e n d s , but the two t h i c k l a t i t e dykes i n the c e n t r a l p o r t i o n of the east w a l l d i p moderately t o the southwest, p a r a l l e l t o the andesite dykes that are a l s o present i n the area. Perhaps a l l dykes w i t h i n the " c e n t r a l dyke package" p r e f e r e n t i a l l y invaded along some weakness i n the rockmass, e.g. an o l d f a u l t zone. Quartz l a t i t e i s r a t e d as strong (R4, 200 MPa u n i a x i a l compressive s t r e n g t h ) . 19 3. The t r a c h y a n d e s i t e dykes (commonly c a l l e d t rachyte) are very s i m i l a r t o the gabbro-monzonite i n t r u s i v e rocks i n appearance. They are coarse g r a i n e d , c o n t a i n i n g up t o 15% bladed p l a g i o c l a s e phenocrysts t h a t are very d i s t i n c t when present. Colour i s dark speckled grey. This dyke type i s r e l a t i v e l y r are i n the Main Zone p i t ; as a r e s u l t , no s t r u c t u r a l trends have been i d e n t i f i e d . Core samples of the dyke were not a v a i l a b l e f o r t e s t i n g , but the t r a c h y t e can be c l a s s i f i e d as R5, very strong rock. U n i a x i a l s t r e n g t h s w i l l l i k e l y be s i m i l a r t o those obtained from gabbro specimens. Dykes are very important i n the o v e r a l l w a l l s t a b i l i t y e v a l u a t i o n because a l t e r e d gouge i s o f t e n present along one or both c o n t a c t s . Any such s u r f a c e must be considered as a low s t r e n g t h throughgoing d i s c o n t i n u i t y that c o u l d provide a r e l e a s e surface f o r a major w a l l f a i l u r e i f unfavourably o r i e n t e d . Dykes a l s o c o n t r o l groundwater seepage i n the Main Zone p i t . Most groundwater seepage i n the p i t w a l l s e x i t s at dyke contacts (see Figure 3.3). Whether t h i s seepage i s caused by the low p e r m e a b i l i t y c l a y gouge t h a t f o r c e s water t o flow along the d i s c o n t i n u i t y or the dykes f r a c t u r e d the adjacent rockmass during i n t r u s i o n t o provide drainage paths of higher p e r m e a b i l i t y i s yet t o be determined. I f the f i r s t hypothesis dominates dykes c o u l d have a very unfavourable i n f l u e n c e on p i t drainage, w e l l s would have t o be l o c a t e d at c l o s e r spacings and c a r e f u l l y p o s i t i o n e d i n the c e n t r a l areas of dyke i s o l a t e d b l o c k s . 3.4 MINERALIZATION Equity S i l v e r Mines L t d . produces concentrates of s i l v e r , copper and g o l d . The p r i n c i p a l source of these metals i s c h a l c o p y r i t e , 20 tetrahedrite and arsenopyrite mineralization. In the Main Zone, the economic minerals occur as fine grained disseminations within the pyroclastic rocks (Unit 2A). Locally, the mineralization grades to massive s u l f i d e , and rarely occurs as veins. The ore genesis model for the Main Zone orebody i s not f u l l y understood. Work by Wetherell (1979) indicates that the ore body i s discordant to the stratigraphy. Therefore, the sulfides must have been emplaced after deposition of the pyrocla s t i c s , but before gabbro monzonite intrusion, because the gabbro does not contain s i g n i f i c a n t amounts of s u l f i d e s . The mineralized zone s t r i k e s approximately north-south and dips at 45°to 60° to the west. The zone extends 700 m along s t r i k e , with a maximum thickness of 90 m. The ore body i s open to depth. Figure 3.3 A THICK ANDESITE DYKE. Notice gouge and groundwater seepage at the contacts. - teas 21 4.0 MINING PROGRAM 4.1 SUMMARY OF PRESENT MINE PLAN The Main Zone p i t design has been updated i n the f a l l of 1984 t o r e f l e c t changes i n metal p r i c e s and t o i n c o r p o r a t e the r e s u l t s of the g e o t e c h n i c a l slope design program. The current u l t i m a t e p i t design i s i l l u s t r a t e d i n P l a n 5 ( i n map envelope). The Main Zone p i t i s o v a l i n shape, the long a x i s i s 830 m i n length and s t r i k e s north - south, p a r a l l e l t o the s t r i k e of the ore body. The p i t w i l l have a maximum width of 530 m c r e s t t o c r e s t . The highest e l e v a t i o n on the p i t c r e s t i s 1360 m, the u l t i m a t e p i t f l o o r w i l l be at 1130 m e l e v a t i o n . As a r e s u l t , the east u l t i m a t e p i t w a l l w i l l be 230 m i n h e i g h t . Access i n t o the u l t i m a t e p i t w i l l be maintained near the present p o s i t i o n , midway along the west w a l l through the notch of the o l d Bessemer Creek channel. The main haul road w i l l be maintained on the west s i d e of the p i t because the g e o t e c h n i c a l study i n d i c a t e s t h a t the west w a l l w i l l be the most s t a b l e , as the m a j o r i t y of d i s c o n t i n u i t i e s d i p i n t o the p i t w a l l . Average p i t w a l l angles used i n the c u r r e n t design are summarized i n Table 4.1. They are the end r e s u l t of a g e o t e c h n i c a l study c a r r i e d out by the mine engineering department from 1983 t o 1984. The methodology used t o determine the optimum p i t w a l l angle i n each design sector i s discussed i n Sections 5 and 9 of t h i s r e p o r t . 22 Table 4.1 PIT WALL MAXIMUM HEIGHT (m) AVERAGE WALL ANGLE (deq) east 230 45 north 180 46 south 190 48 west 170 48 west 170 40 (with ramps) Mining w i l l progress on 5 m benches f o r maximum ore - waste s e l e c t i v i t y . Eight meter wide berms w i l l be maintained every 20 m i n accordance w i t h the Mining Regulations Act. 4.2 INNER PIT / PUSHBACK To increase the ore/waste r a t i o during the e a r l y years of mine l i f e the Main zone p i t i s being excavated i n two stages. An i n t e r i o r p i t i s being developed i n the core of the Main Zone. T h i s p i t w i l l be completed t o a depth of 1190 m. Waste rock i s being mined simultaneously on the upper benches of the u l t i m a t e p i t ; however, the i n t e r i o r p i t w i l l be completed s e v e r a l years before the u l t i m a t e p i t reaches the 1190 m e l e v a t i o n . The i n t e r i o r p i t w i l l p rovide e x c e l l e n t exposures f o r c o l l e c t i o n o f s t r u c t u r a l data c l o s e t o the u l t i m a t e p i t w a l l . The present design of the west u l t i m a t e p i t i s based on observations that were at times p r o j e c t e d as much as 400 m t o where they were a p p l i e d . The present u l t i m a t e p i t design must be re-evaluated once the i n t e r i o r p i t i s completed and a l l s t r u c t u r a l i n f o r m a t i o n has been c o l l e c t e d . A second major advantage of the i n t e r i o r p i t i s that a f a i l u r e encompassing 2 t o 3 berms can be t o l e r a t e d provided i t occurs i n an area where i t w i l l not i n f l u e n c e p r o d u c t i o n . Two areas should be 23 oversteepened i n the i n t e r i o r p i t i n an attempt t o induce f a i l u r e . One t r i a l should be c a r r i e d out t o steepen the berm face angle t o 70°on the southern end of the i n t e r i o r p i t west w a l l . I f the berm can be maintained at 70° without f a i l u r e then the design of the u l t i m a t e p i t west w a l l should be reevaluated and p o s s i b l y steepened t o an o v e r a l l p i t w a l l angle of 53°(before haul road). The second t r i a l should be on the east w a l l of the i n t e r i o r p i t . A wedge s t r u c t u r e formed by two major d i s c o n t i n u i t i e s should be i d e n t i f i e d and the slope steepened u n t i l that s t r u c t u r e d a y l i g h t s . By performing a back a n a l y s i s on any induced f a i l u r e a b e t t e r estimate of f r i c t i o n angle can be achieved, and w i l l r e s u l t i n a more accurate assesment of the f a c t o r of s a f e t y i n the east w a l l . 24 5.0 MAIN ZONE STRUCTURAL GEOLOGY 5.1 PAST PROGRAMME • The mine engineering department at Equity carried out a preliminary pit design investigation in 1983. The goal of this study was to determine whether steepening of the pit walls in the Main Zone appeared feasible and whether a more detailed investigation was warranted. The study consisted of line mapping and structural analysis of the data. Line mapping information was entered into the Placer computer system. The data was processed with the Discodat program package. Stereonets generated by the program were analyzed to define structural domains and design sectors in the Main zone. The study concluded that steepening of the pit walls appeared feasible on the west side of the pit and that a more detailed geotechnical slope design program was required to further define the observed structural trends. 5.2 STRUCTURAL MAPPING PROGRAM A detailed line mapping program was completed in the summer of 1984. A l l safely accessible berms in the Main Zone pi t that were not mapped in 1983 were carefully examined. In a l l , 64 line mapping traverses were completed, each approximately 30 m in length. Approximately 1920 m of berm were mapped in total. Information that was collected during the traverses included: 1) location, 2) discontinuity type, 3) discontinuity orientation, 4) length, 5) width, 6) spacing, 7) lithology, 8) rockmass hardness, and 9) groundwater conditions. The data was recorded on a standard Discodat coding form and later entered into the computer. 25 Because the Main zone p i t i s l o c a t e d on a we s t e r l y s l o p i n g h i l l s i d e and i s i n the e a r l y stages of development very l i t t l e rock has been exposed on the west p i t w a l l . Approximately 50% of s t r u c t u r a l data used i n t h i s study was c o l l e c t e d on the east w a l l of the u l t i m a t e p i t and 50% on the south, e a s t , and west w a l l s of the i n t e r i o r p i t . The l o c a t i o n of each t r a v e r s e i s p l o t t e d on Plan 3. 5.3 STRUCTURAL DOMAINS S t r u c t u r a l domains are areas w i t h i n a p i t that have c o n s i s t e n t rock type and s t r u c t u r a l o r i e n t a t i o n s . Based on r e s u l t s of the l i n e mapping programs the Main Zone has been d i v i d e d i n t o four s t r u c t u r a l domains. The c h a r a c t e r i s t i c s of each s t r u c t u r a l domain are summarized i n the f o l l o w i n g four subsections. The in f o r m a t i o n f o r each s t r u c t u r a l domain i s i l l u s t r a t e d on four s t e r e o nets t h a t i n c l u d e : 1) O r i e n t a t i o n s of "major s t r u c t u r e s " i n c l u d i n g f a u l t s , shears and dykes. These s t r u c t u r e s are very continuous and gouge i s u s u a l l y present on the d i s c o n t i n u i t i e s ; t h e r e f o r e , they w i l l have the g r e a t e s t i n f l u e n c e on f u l l w a l l s t a b i l i t y . 2) The " a l l major s t r u c t u r e s " stereonet shows the d i s t r i b u t i o n of poles t o f a u l t s , shears, dykes and major j o i n t s . This stereonet i s used i n the m a j o r i t y of design work because i t shows the peak o r i e n t a t i o n s of a l l continuous planes t h a t c o u l d form r e l e a s e s u r f a c e s . Because i n most areas of the p i t there are many more major j o i n t s than any other major s t r u c t u r e s the j o i n t s can mask very important s t r u c t u r a l trends i n the l a r g e r major d i s c o n t i n u i t i e s . That i s why the f a u l t s , dykes and shears are t r e a t e d s e p a r a t e l y i n stereonet 1. The f i r s t t a b l e i n each s t r u c t u r a l domain s e c t i o n summarizes the most important peak o r i e n t a t i o n s 26 from the two stereonets. 3) The peak orientations of each discontinuity type are summarized in the third figure in each structural domain section. A unique symbol is used to identify each type of discontinuity and a number indicates the relative size of each peak on that stereonet (e.g. 1 implies the largest peak). A legend that explains what discontinuity each symbol represents is presented in Table 5.1. The stereonets for each discontinuity type from which the "poles to major structures by type" figures were constructed are presented in Appendix A. 4) A l l wedge, plane, block, and toppling failure modes that are formed by planes with orientations of the peak major discontinuities as determined in 1) and 2) are shown in the fourth figure in each structural domain. This figure i s t i t l e d "failure modes". It must be realized that many of these failure modes w i l l not be dangerous because they may dip into the p i t wall, or too steeply to daylight. They may also dip so f l a t that the dip angle of the intersection w i l l be shallower than the angle of f r i c t i o n and sliding w i l l not be possible. A s t a b i l i t y assessment that considers pit wall geometry and shear strength characteristics is carried out for each design sector in section 9 of this report. The type of failure described by the terminology used in this paragraph is explained on the next page and sketches of a typical failure in each category are shown in Figure 5.0. A plane failure is the simplest failure mechanism. A mass of rock slides out on a single plane. For this failure to occur the failure surface must strike nearly parallel to the wall (+/- 10*) of f r i c t i o n and cohesion. Some form of lateral release surfaces must 27 Table 5.1 SYMBOLS AND CODES USED IN STEREONETS Symbol D i s c o n t i n u i t y Type Symbol S i z e Symbol S i z e o f a u l t 1 > 1 G > 16 2 > 2 H > 17 • shear 3 > 3 I > 18 o 4 > 4 J > 19 major j o i n t 5 > 5 K > 20 6 > 6 L > 21 A dyke 7 > 7 M > 22 8 > 8 N > 23 Symbol F a i l u r e Mode 9 > 9 0 > 24 o A > 10 P > 25 plane B > 11 Q > 26 A C > 12 R > 27 wedge D > 13 S > 28 o E > 14 T > 29 t o p p l i n g F > 15 U > 30 1. s i z e i n d i c a t e s the t o t a l weight of poles w i t h i n a c i r c l e t hat has an area equal t o 1% of the stereonet and centered on the peak of the of the d i s t r i b u t i o n . be present t o a l l o w the rockmass t o f a l l out unless the plane i s s i t u a t e d on a convexity so the s i d e s a l s o d a y l i g h t out of the w a l l as was the case on one of the l a r g e f a i l u r e s i n the Southern T a i l p i t . A wedge f a i l u r e i s formed by two i n t e r s e c t i n g d i s c o n t i n u i t i e s . For a wedge t o be unstable i t must d a y l i g h t ; the l i n e of i n t e r s e c t i o n of the two planes must d i p shallower than the face of the s l o p e . As a rough r u l e of thumb the l i n e of i n t e r s e c t i o n must a l s o d i p steeper than the f r i c t i o n angle f o r s l i d i n g t o occur. A d e t a i l e d s t a b i l i t y e v a l u a t i o n that considers wedge geometry, shear s t r e n g t h parameters on each f a i l u r e s u r f a c e , and pore pressure w i l l u s u a l l y show th a t a wedge w i l l be s t a b l e even when i t plunges c o n s i d e r a b l y steeper than the angle of f r i c t i o n because a l a r g e component of the s t a b i l i z i n g f o r c e i s d e r i v e d from the increased surface area on the f a i l u r e plane per u n i t mass. This i s e s p e c i a l l y t r u e when the wedge becomes very t i g h t . 28 A block f a i l u r e i s r e a l l y a plane f a i l u r e with a v e r t i c a l t e n s i o n crack. The f a i l u r e plane i s u s u a l l y f l a t l y i n g ( l e s s than 20°) and the f a i l u r e i s d r i v e n by pore water pressures developed i n the t e n s i o n crack. This f a i l u r e mode i s much l e s s common i n hardrock mines than the f i r s t two modes disc u s s e d . Toppling occurs when d i s c o n t i n u i t i e s d i p very s t e e p l y and s t r i k e n e a r l y p a r a l l e l t o the p i t w a l l face. I f the sheets of rock are overhanging or s u f f i c i e n t l y l a r g e water pressures e x i s t the top of the sheet can become unstable and l i t t l e by l i t t l e the e n t i r e berm or p i t w a l l can loose i t s i n t a c t n e s s and become a p i l e of boulders. Toppling i s a p r o g r e s s i v e f a i l u r e t h a t u s u a l l y takes some time t o develop and i s f a i r l y uncommon i n mines, but may occur i n i s o l a t e d zones on the west w a l l of the Main Zone p i t . The f i n a l f a i l u r e mode th a t has been observed i n the Main Zone i s step f a i l u r e . T his f a i l u r e occurs only i n h e a v i l y j o i n t e d rockmasses where j o i n t s e t s are c l o s e l y spaced and d i s c o n t i n u o u s . Numerous cross j o i n t s must a l s o be present. The a c t u a l f a i l u r e plane steps across from one j o i n t to another and can d i p c o n s i d e r a b l y steeper than the j o i n t s e t . T h i s f a i l u r e mode w i l l not r e s u l t i n l a r g e f a i l u r e s , but appears t o l i m i t the steepness of the berm face i n the v o l c a n i c s t o 66°. 29 Figure 5.0 COMMON FAILURE MODES IN OPEN PITS ISOMETRIC X-SECTION FAILURE MODE DISPLACEMENT VECTORS WEDGE - REQUIRES TWO INTERSECTING PLAfCS - TENSION CRACK NAY DEVELOP - STABILITY FUNCTION OF WEDGE GEOMETRY, SCAR STRQCTH AND GROUNDWATER A ^^ ^^ ^^ ^^ ^^ ^^ ^ PLANE - WVEICNT ON iM£ PLffC - REQUIRES LATERAL RELEASE SURFACES - PLANE PARALLEL TO FACE •/- 21 - MUST DAYLIEHT A X FT. \ \ \ IA BLOCK - RARE IN HARD ROCK NifCS - DRIVEN BY HATER PRESSURE IN TENSION CRACK - USUALLY REQUIRES LOU STRENGTH BASAL PU»£, E.B. CLAY \ in TOPPLING \ • REQUIRES STEEPLY OIPPIW JOINTS - MILL OCCUR ON-Y IN LOCAL AREAS IN RAIN IDC >Ov*S STEP - KILL OCCUR ONLY IN VOLCANICS - REQUIRES CLOSELY SPACED AND 01SCTJNT1MJ0US JOINTS - CONTROLS BERN FACE ANGLE - STABILITY LIKELY A FUNCTION OF TR1N BLAST 1(6 REDCD -\ r \ r 30 5.3.1 S t r u c t u r a l Domain D l LOCATION: S t r u c t u r a l Domain D l comprises the south and west w a l l s of the Main Zone p i t . To date, t h i s domain has been defined along exposed w a l l s of both I n t e r i o r and Ultimate p i t s between e l e v a t i o n s 1285 t o 1360 m. I t i s l i k e l y t h a t the domain extends across most of the curr e n t p i t f l o o r on 1285 bench and t o the we s t e r l y d i p p i n g gabbro contact at depth. GEOLOGY: L a p i l l i t u f f i s the dominant l i t h o l o g i c u n i t i n t h i s domain. L o c a l i z e d zones of ash and dust t u f f are a l s o present. Dykes of the three main compositions penetrate the v o l c a n i c s . Most of these dykes are l e s s than 2 m t h i c k , abnormally t h i n i n comparison t o dykes i n other areas of the Main zone. SELECTION: S t r u c t u r a l domain D l was defined on the b a s i s of l i t h o l o g y , ( l a p i l l i t u f f ) , and a strong s t r u c t u r a l trend i n the major d i s c o n t i n u i t i e s ( s t r i k i n g east-west, and n e a r l y v e r t i c a l ) . ORIENTATIONS: Fi v e c l u s t e r s of o r i e n t a t i o n trends were i d e n t i f i e d i n domain D l . The peak o r i e n t a t i o n s of these trends are summarized i n Table 5.2; the stereonets used t o d e f i n e the trends are shown i n Figures 5.1 & 5.2. The dominant o r i e n t a t i o n s of major s t r u c t u r e s i n t h i s domain s t r i k e e a s t e r l y , d i p p i n g s t e e p l y t o the south. This o r i e n t a t i o n t r e n d i s observed i n a l l the major s t r u c t u r e s i n c l u d i n g f a u l t s , c o n t a c t s , shears, and major j o i n t s ; as can be seen i n Figure 5.3. This f i g u r e shows the peak o r i e n t a t i o n s of each major s t r u c t u r e by type. 31 Because much of the line mapping in this domain was carried out on bench walls running north south, most of the structures were coming straight out of the wall. The Terzaghi correction factor for these structures was therefore very low as the true spacing was observed. The few structures that had strikes near parallel to the traverse line were assigned very high correction factors and a r t i f i c i a l l y dominated the corrected stereonet plots. Because f i e l d observations do not indicate that the structures are as dominant as the corrected plot suggests a l l analysis in this structural domain is based on uncorrected stereonet plots. Table 5.2 Orientations of Major Structures Peak Dip Direction Dip Size Weighted Percentage (deg) (deg) Code of Population in Peak A 157 67 7 7 B 179 77 7 7 C 256 55 5 5 D 224 55 3 3 E 76 88 3 3 Table 5.3 Orientations of Major Structures by Type Type Peak Dip Direction Dip Size Weighted Percentage (deg) (deg) Code of Population in Peak FL 1 152 70 H 17 FL 2 246 62 H 17 FL 3 189 85 A 10 CN 1 176 74 B 11 CN 2 74 88 B 11 CN 3 251 53 8 8 SR 1 178 86 F 15 SR 2 200 45 A 10 SR 3 219 42 A 10 MJ 1 175 78 9 9 MJ 2 256 68 7 7 MJ 3 006 82 6 6 32 33 FAILURE MODES: The four groups of m a j o r ' d i s c o n t i n u i t i e s combine t o form ten p o s s i b l e f a i l u r e modes. The f a i l u r e types and o r i e n t a t i o n s are summarized i n Table 5.4. A stereonet showing the p o s s i b l e f a i l u r e modes i n t h i s domain i s shown i n Figure 5.4. Table 5.4 F a i l u r e Modes - Domain D l F a i l u r e # Mode D i r e c t i o n of S l i p Plunge (cleg) (deg) 1 wedge 252 48 2 wedge 247 55 3 wedge 228 52 4 wedge 217 48 5 wedge 212 52 6 wedge 157 74 7 wedge 163 32 8 wedge 112 57 9 plane 156 55 10 t o p p l i n g 265 3 over Which f a i l u r e modes i n Table 5.4 w i l l be k i n e m a t i c a l l y unstable w i l l depend on p i t w a l l geometry. Figure 5.4 i n d i c a t e s that most s t a b i l i t y problems i n t h i s domain w i l l be encountered on w a l l s t h a t trend 320°(NW-SE). F o r t u n a t e l y , no p i t w a l l s have t h i s unfavourable o r i e n t a t i o n i n t h i s s t r u c t u r a l domain. For the curr e n t p i t design f a i l u r e modes #8 and #10 are the most unfavourable and w i l l i n f l u e n c e p i t design. Mode #8 i s a wedge f a i l u r e t h a t plunges at 57° t o the south east. I t cou l d r e s u l t i n s i n g l e berm wedge f a i l u r e s on west t o north-west p i t w a l l s . Large, f u l l w a l l f a i l u r e s may r e s u l t i f o v e r a l l p i t angle i s steepened t o undercut the wedges. Mode #10, t o p p l i n g , may occur on benches of the west and south-west w a l l s . As the p i t i s concave i n t h i s area t o p p l i n g should be confined t o f a i l u r e s l e s s than 100 m i n length and should not pose s i g n i f i c a n t s t a b i l i t y problems. 34 N Figure 5.3 DOMAIN Dl POLES TO MAJOR STRUCTURES BY TYPE 35 5.3.2 Sructural Domain D2 LOCATION: Structural domain D2 is located in the southeastern corner of the Main Zone p i t . The northern boundary of the domain i s formed by a series of thick dykes, the southern by the gabbro-volcanic contact. Pit walls in this domain trend north - south to northeast - southwest. To date this domain has been defined along exposed walls of both interior and ultimate pits between elevations of 1285 and 1360 m. It is likely that the domain extends along the gabbro volcanic contact to the south and to depth. GEOLOGY: Structural domain D2 is formed by the gabbro rocks close to the gabbro-volcanic contact that dips at approximately 50° to the west, into the p i t . L a p i l l i tuff is also present in small areas within D2, especially below 1320 m elevation. A thick, east-west trending quartz l a t i t e dyke bisects the domain. It dips steeply to the south. Several thinner (2 to 5 m) andesite dykes are also present, some have sub-parallel orientations to the quartz l a t i t e , a second set trends northwest - southeast. SELECTION: The main selection c r i t e r i a in this domain are the gabbro lithology and proximity to the gabbro volcanic contact. A very strong easterly dipping trend in joint orientation is also unique to this domain. The boundaries of D2 are formed by a series of several thick andesite and quartz l a t i t e dykes to the north and the gabbro - volcanic contact to the south. In both cases the boundaries are marked by changes in structural orientations, especially in the joint population. 36 ORIENTATIONS: S i x c l u s t e r s o f • o r i e n t a t i o n trends were i d e n t i f i e d i n domain D2. Four are strong primary peaks w h i l e peaks D and E are secondary highs on the f l a n k s of the primary c l u s t e r s . The contoured stereonet p l o t of the major d i s c o n t i n u i t i e s (without major j o i n t s ) i s shown i n Figure 5.5. Figure 5.6 i s a p l o t of a l l major d i s c o n t i n u i t i e s i n c l u d i n g major j o i n t s . I t i s not used as the p r i n c i p a l design d i s t r i b u t i o n because the very strong trend i n major j o i n t s masks a l l other major s t r u c t u r e s . Weighted stereonets were used f o r a n a l y s i s i n t h i s domain because the weighting d i d not a t t a c h e xcessive importance t o a few s t r u c t u r e s of minor s i g n i f i c a n c e as was the case i n domain D l . The dominant o r i e n t a t i o n i n t h i s domain i s a n o r t h e r l y s t r i k e , d i p p i n g moderately t o s t e e p l y (45°- 80°) t o the west. I t i s observed i n a l l major s t r u c t u r e s but i s most prominent i n the j o i n t p o p u l a t i o n . Table 5.5 summarizes the s i x peak o r i e n t a t i o n s of major s t r u c t u r e s i n domain D2. Table 5.6 l i s t s the peak o r i e n t a t i o n s by s t r u c t u r e type. These o r i e n t a t i o n s are a l s o p l o t t e d on a stereonet i n Figure 5.7. Table 5.5 O r i e n t a t i o n s of Major S t r u c t u r e s - Domain D2 Peak Dip D i r e c t i o n Dip S i z e Weighted Percentage (deg) (deg) Code of P o p u l a t i o n i n Peak A 267 51 H 17 B 136 47 A 10 C 173 83 A 10 D 146 62 7 7 E 295 69 5 5 F 253 67 5 5 37 Table 5.6 O r i e n t a t i o n s of Major S t r u c t u r e s by Type - Domain D2 Type Peak Dip' D i r e c t i o n Dip S i z e Weighted Percentage (deg) (deg) Code of P o p u l a t i o n i n peak FL 1 292 69 I 18 FL 2 253 58 F 15 FL 3 172 83 D 13 CN 1 259 54 U 30 CN 2 172 83 E 14 CN 3 198 74 A 10 SR 1 135 48 M 22 SR 2 • 272 44 H 17 SR 3 347 82 8 8 MJ 1 256 58 I 18 FAILURE MODES: The s i x groups of major d i s c o n t i n u i t i e s combine t o form 21 p o s s i b l e f a i l u r e modes. Each f a i l u r e type and o r i e n t a t i o n i s l i s t e d i n Table 5.7. The f a i l u r e planes and o r i e n t a t i o n s of l i n e s of i n t e r s e c t i o n are p l o t t e d i n Figure 5.8. Table 5.7 F a i l u r e Modes - Domain D2 F a i l u r e # Mode D i r e c t i o n of S l i p Plunge (deg) (deg) 1 wedge 324 29 2 wedge 265 66 3 wedge 252 50 4 wedge 248 62 5 wedge 244 66 6 wedge 224 41 7 wedge 206 30 8 wedge 212 35 9 wedge 209 15 10 wedge 198 24 11 wedge 194 50 12 wedge 180 35 13 wedge 90 48 14 wedge 87 33 15 wedge 67 22 16 plane 292 69 17 plane 266 50 18 plane 292 69 19 plane 145 62 20 plane 135 44 21 t o p p l i n g 352 8 over 39 Because the p i t w a l l s i n t h i s domain w i l l t r e n d north - south and northeast - southwest the unfavourable f a i l u r e modes w i l l have d i r e c t i o n s of plunge between 170° & 330° and plunge between 30° & 70°. Wedge f a i l u r e s 1 - 8 and 11 - 12, plane f a i l u r e s 16 - 18, and t o p p l i n g f a i l u r e 21 have k i n e r n a t i c a l l y unstable o r i e n t a t i o n s . For the eastern p i t w a l l i n domain D2 the most important k i n e r n a t i c a l l y p o s s i b l e f a i l u r e s are: wedge 3 - bench f a i l u r e s , w a l l wedge 4 - bench f a i l u r e s , w a l l wedge 6 - bench f a i l u r e s , w a l l wedge 7 - bench f a i l u r e s , w a l l plane 17 - bench f a i l u r e s , w a l l f a i l u r e s i f p i t steeper than 51° f a i l u r e s i f p i t steeper than 62° f a i l u r e s i f p i t steeper than 52° f a i l u r e s i f p i t steeper than 43° f a i l u r e s i f p i t steeper than 50° Wedge 7 plunges o b l i q u e l y t o the p i t w a l l and w i l l not be as s i g n i f i c a n t as the 43 degree angle of plunge suggests. F a i l u r e modes 2, 5, 16, and 18 plunge too s t e e p l y t o a f f e c t f u l l w a l l s t a b i l i t y , but may r e s u l t i n s m a l l berm f a i l u r e s . Far fewer k i n e r n a t i c a l l y unstable f a i l u r e modes can be i d e n t i f i e d along the southeastern w a l l s o f domain D2. Wedge 1 i s the only f u l l w a l l f a i l u r e mode p o s s i b l e on t h i s w a l l , as i t w i l l plunge shallower than the slo p e angle. However, because the angle of plunge i s only 29° shear s t r e n g t h should be s u f f i c i e n t t o prevent t h i s wedge from f a i l i n g . F a i l u r e mode 3 may r e s u l t i n minor berm f a i l u r e s . 40 N Figure 5.7 DOMAIN D2 POLES TO MAJOR STRUCTURES BY TY F i g u r e 5.8 DOMAIN 02 FAILURE MODES 41 5.3.3 S t r u c t u r a l Domain D3 LOCATION: Domain D3 i s located i n the east h a l f of the Main Zone p i t below 1320 m el e v a t i o n . To the south the domain extends beyond the ultimate p i t boundary, to the north i t i s terminated by the gabbro contact at 7750 m North. At present, the western boundary of t h i s domain i s not c l e a r l y defined; i t i s assumed to extend beyond the ultimate p i t walls. GEOLOGY: The dominant rock unit i n D3 i s l a p i l l i t u f f . Minor dust t u f f i s als o present. A thick package of dykes cuts across the c e n t r a l part of the domain. These dykes plunge steeply (60-70*) to the southwest. A f i v e meter wide quartz l a t i t e dyke runs along the southern domain boundary. P i t walls i n D3 have formed along major d i s c o n t i n u i t i e s , numerous berm s i z e plane and wedge f a i l u r e s can be seen i n the w a l l . This i s i n contrast with the volcanics of domain Dl where step f a i l u r e s along minor d i s c o n t i n u i t i e s c o n t r o l s t a b i l i t y of the berms. SELECTION: Domain D3 has been defined by the volcanic l i t h o l o g y and a very strong o r i e n t a t i o n trend i n the major d i s c o n t i n u i t i e s ( i . e . f a u l t s , shears, and contacts), dipping steeply to the southwest. The east and south domain boundaries are defined by the gabbro - volcanic l i t h o l o g y change. The southern boundary between D3 and Dl has been i d e n t i f i e d by a change i n d i s c o n t i n u i t y o r i e n t a t i o n . At present t h i s boundary i s assumed to extend i n a v e r t i c a l plane trending east - west. Further s t r u c t u r a l mapping and analysis i s required i n the west h a l f of the Main zone to c l e a r l y define t h i s boundary. 42 N J L 43 ORIENTATIONS: Two principal orientation groups are observed in D3. The majority of faults, shears, and contacts plunge steeply to the south, while the principal major joint orientation is a plunge of approximately 50*to the west. Table 5.8 summarizes the peak orientations of the five largest clusters. The stereonets used to define the peaks are presented in Figures 5.9 & 5.10. Table 5.8 Orientations of Major Structures - Domain D3 Peak Dip Direction Dip Size Weighted percentage (deg) (deg) Code of Population in Peak A 262 58 E 14 A 196 60 E 14 B 232 64 E 14 C 182 78 B 11 D - 195 35 A 10 Table 5.9 Orientations of Major Structures by Type - Domain D3 Type Peak Dip Direction Dip Size Weighted percentage (deg) (deg) Code of Population in Peak FL 1 181 50 P 25 FL 2 287 61 H 17 FL 3 138 26 G 16 CN 1 190 39 J 19 CN 2 232 66 I 18 CN 3 031 66 A 10 SR 1 176 74 J 19 SR 2 283 66 A 10 MJ 1 260 56 J 19 MJ 2 204 63 H 17 FAILURE MODES: Thirteen failure modes have been identified in domain D3. The type and orientation of each failure mode is presented in Table 5.10. A stereoplot of the controlling discontinuities i s shown in Figure 5.12. A majority of the failures plunge steeply. As a result, they w i l l 44 not d a y l i g h t out of the o v e r a l l slope so they w i l l not a f f e c t the slope angle d i r e c t l y . However, four f a i l u r e modes do have unfavourable o r i e n t a t i o n s , i n the east w a l l of the i n t e r i o r p i t only wedge f a i l u r e 3 could r e s u l t i n a f u l l s l o p e f a i l u r e . As the wedge i s very t i g h t and has a shallow plunge i t proves s t a b l e i n a d e t a i l e d a n a l y s i s , ( f . o . s = 5.0 d r y ) . W a l l s t a b i l i t y on east w a l l s w i l l t h e r e f o r e be governed by bermface angle. Numerous f a i l u r e modes d a y l i g h t out of the east and south w a l l s once the berm angle i s increased above 50°. Therefore, bench f a i l u r e s must be expected on the east w a l l i n t h i s domain and adequate berms l e f t t o cat c h s l i d e d e b r i s . On the south w a l l s plane f a i l u r e 11 i s unfavourably o r i e n t e d , plunging out of the w a l l at 34°. The same plane can combine with planes A' and A t o form wedges 8 & 9 that a l s o plunge at shallow angles. F o r t u n a t e l y , plane D represents the s m a l l e s t c l u s t e r used i n the a n a l y s i s ; t h e r e f o r e , only a s m a l l number of these unfavourable planes are expected i n the south end of the Main Zone. Table 5.9 F a i l u r e Modes - Domain D3 F a i l u r e # Mode D i r e c t i o n of S l i p Plunge (deg) (deg) 1 wedge 272 58 2 wedge 270 12 3 wedge . 264 34 4 wedge 254 57 5 wedge 246 64 6 wedge 235 56 7 wedge 198 60 8 wedge 198 34 9 wedge 158 28 10 plane 231 64 11 plane 197 34 12 plane 196 70 13 t o p p l i n g 003 12 over 45 46 5.3.4 S t r u c t u r a l Domain D4 LOCATION: S t r u c t u r a l Domain D4 i s l o c a t e d i n the northeast corner of the Main Zone. To the south the domain extends t o the o l d Bessemer Creek drainage. The north boundary of the domain i s beyond the u l t i m a t e p i t w a l l and has not been d e f i n e d . The west boundary between D4 and D3 i s formed by the gabbro - v o l c a n i c contact that runs approximately north -south along g r i d coordinate 8750 E. To the east, the domain a l s o extends beyond the u l t i m a t e p i t w a l l . GEOLOGY: Gabbro i s the dominant l i t h o l o g i c u n i t i n D4. I t occurs as a large and elongated tongue l i k e i n t r u s i o n t h a t extends northward from the main gabbro p l u t o n . To the east and west the tongue i s surrounded by v o l c a n i c r o c k s , p r i m a r l y l a p i l l i t u f f . Unique t o t h i s domain i s a 30 m wide band of v o l c a n i c conglomerate. The o r i e n t a t i o n and c o n t i n u i t y of t h i s stratum remains t o be d e f i n e d . Moderately t h i c k (3-5 m) qu a r t z l a t i t e and andesite dykes have i n t r u d e d i n t o both rock types. The dominant o r i e n t a t i o n of these s t r u c t u r e s i s a south w e s t e r l y plunge. SELECTION: Boundaries f o r t h i s domain were s e l e c t e d t o f u l l y c o n t a i n the gabbro tongue. To the south, the domain boundary was s e l e c t e d at the Bessemer Creek dyke package because a f a u l t i s suspected i n the area and the s t r u c t u r a l o r i e n t a t i o n s south of the dyke zone d i f f e r from those observed t o the no r t h . A strong east-west tre n d i n the o r i e n t a t i o n of f a u l t s , c o n t a c t s , and shears i s dominant i n t h i s domain. 47 48 ORIENTATIONS: Two strong s t r u c t u r a l trends are evident i n Figures 5.13 and 5.14. F i r s t , most of the major s t r u c t u r e s plunge s t e e p l y t o the south, generating a very strong c l u s t e r (A) i n the north corner of Figure 5.13. The second t r e n d , a moderate w e s t e r l y plunge i s very evident i n the j o i n t p o p u l a t i o n (see Figure 5.14). Weighted stereonets were used i n the a n a l y s i s of t h i s domain as they appeared t o best represent the s t r u c t u r a l data observed i n the s t r u c t u r a l geology p l a n (Plan 2.). Table 5.11 summarizes the peak o r i e n t a t i o n s of the four l a r g e s t c l u s t e r s i n the s t r u c t u r a l f a b r i c . Table 5.12 l i s t s the dominant o r i e n t a t i o n s of each major d i s c o n t i n u i t y type. Table 5.11 O r i e n t a t i o n s of Major S t r u c t u r e s - Domain D4 Peak Dip D i r e c t i o n Dip S i z e Weighted Percentage (deg) (deg) Code of P o p u l a t i o n i n Peak A 206 73 F 15 B 240 44 8 8 C 272 67 7 7 D 166 61 5 5 Table 5.12 O r i e n t a t i o n s of Major S t r u c t u r e s by Type - Domain D4 Type Peak Dip D i r e c t i o n Dip S i z e Weighted Percentage (deg) (deg) Code of P o p u l a t i o n i n Peak FL 1 271 66 H 17 FL 2 226 60 E 14 FL 3 205 71 C 12 CN 1 208 74 L 21 CN 2 240 44 K 20 SR 1 194 79 0 24 SR 2 267 74 F 15 MJ 1 238 60 B 11 MJ 2 262 46 A 10 MJ 3 287 46 7 7 49 FAILURE MODES: The four dominant d i s c o n t i n u i t i e s combine t o form 10 p o s s i b l e f a i l u r e modes (see Figure 5.16). As domain D4 i s i n the northeast corner of the u l t i m a t e p i t only f a i l u r e modes th a t plunge i n t o the the southeast and southwest quadrants of the s t e r e o p l o t must be considered dangerous. In the east w a l l f a i l u r e modes 1, 3, and 9 w i l l be k i n e n a t i c a l l y u n stable. Wedge 1 plunges at only 37 degrees t o the west. As shear s t r e n g t h t e s t s i n d i c a t e that the f r i c t i o n angle i s l e s s than 37° i t i s very l i k e l y t h a t any wedges th a t have t h i s o r i e n t a t i o n w i l l be unstable and may f a i l on plane B i f undercut. Plane B w i l l a l s o c o n t r o l s t a b i l i t y on southwest f a c i n g w a l l s . Plane f a i l u r e 9 w i l l d a y l i g h t i f w a l l s become steeper than 45°. L a t e r a l r e l e a s e surfaces w i l l be formed by planes C & D (wedges 5 & 3 ) . No f u l l w a l l s t a b i l i t y problems are a n t i c i p a t e d on south f a c i n g w a l l s as long as o v e r a l l w a l l angle does not exceed 50°. Planar berm f a i l u r e s can be expected on plane D ( f a i l u r e modes 3, 4, & 10) i f berm face angles exceed 55°. Table 5.13 F a i l u r e Modes - Domain D4 F a i l u r e # Mode D i r e c t i o n of S l i p Plunge (deg) (deg) 1 wedge 282 36 2 wedge 250 65 3 wedge 224 44 4 wedge 212 50 5 wedge 199 37 6 wedge 147 58 7 wedge 270 66 8 plane 204 72 9 plane 239 44 10 plane 166 60 50 51 6.0 GROUNDWATER HYDROLOGY The problem of groundwater seepage i n t o the Main Zone p i t i s becoming more troublesome as mining progresses t o depth. Larger q u a n t i t i e s of water have t o be pumped from the p i t f l o o r sump, a greater percentage of b l a s t holes have t o be loaded w i t h more expensive s l u r r y e x p l o s i v e s , and t i r e l i f e i s l i k e l y becoming s h o r t e r because equipment has t o operate on wetter ramps w i t h i n the p i t . Groundwater"also has a a d e s t a b i l i z i n g i n f l u e n c e on any p o t e n t i a l slope f a i l u r e s . Therefore, i n areas where high water pressures are a n t i c i p a t e d , the p i t w a l l s have t o be designed at shallower angles then i n a dry w a l l t o a t t a i n the same f a c t o r of s a f e t y a g a i n s t f a i l u r e . Because dewatering of the Main zone p i t would reduce o p e r a t i o n a l c o s t s i n e x p l o s i v e s , t i r e s , and waste rock t r a n s p o r t e d ; a p r e l i m i n a r y study was c a r r i e d out i n the summer of 1984 t o determine whether p i t dewatering i s t e c h n i c a l l y p o s s i b l e . P e r m e a b i l i t y t e s t i n g and piezometer monitoring programs were developed t o pr o v i d e i n f o r m a t i o n on h y d r o l o g i c parameters. In combination w i t h a v a i l a b l e g e o l o g i c data and observations of s u r f i c i a l water c o n d i t i o n s , the t e s t r e s u l t s were used t o develop a greater understanding o f the h y d r o l o g i c regime i n the v i c i n i t y of the p i t . Based on t h i s understanding i t was p o s s i b l e t o i d e n t i f y areas where the gr e a t e s t water problems can be expected, and where some form of dewatering would prove of most b e n e f i t t o operations. S e v e r a l methods of dewatering t h a t would l i k e l y prove very e f f e c t i v e i n the Main Zone are then introduced. 52 A numerical model was developed t o simulate the performance of a dewatering w e l l i n the Main zone environment. The model was used t o t e s t whether the rock mass p e r m e a b i l i t i e s are s u f f i c i e n t l y high t o a l l o w s u c c e s s f u l dewatering. A s e n s i t i v i t y study was a l s o c a r r i e d out to determine which h y d r o l o g i c parameters have the gr e a t e s t i n f l u e n c e on w e l l behaviour and should t h e r e f o r e be e s t a b l i s h e d before a pumping system i s designed. The expected performance of the h o r i z o n t a l drainage systems i s a l s o d i s c u s s e d , but i n a q u a l i t a t i v e manner, because the complex geometry of the p i t w a l l and h o r i z o n t a l d r a i n s cannot be evaluated by a simple a n a l y t i c a l s o l u t i o n . A more d e t a i l e d numerical s i m u l a t i o n u t i l i z i n g f i n i t e d i f f e r e n c e or f i n i t e element techniques would be re q u i r e d t o study t h i s problem. A more p r a c t i c a l approach would be t o perform an i n - p i t t r i a l of the system t o t e s t i t s e f f e c t i v e n e s s and then c a l i b r a t e a numerical model w i t h the observed r e s u l t s f o r f u r t h e r a n a l y s i s and s e n s i t i v i t y s t u d i e s . 53 6.1 LOCATION OF TEST SITES A l l piezometer monitoring s i t e s have been l o c a t e d i n the east h a l f of the Main Zone p i t , along berms of the east u l t i m a t e p i t w a l l and the u l t i m a t e p i t c r e s t . Figure 6.1 i s a p l a n of the Main Zone p i t t h a t shows the p o s i t i o n of a l l piezometer and p e r m e a b i l i t y t e s t l o c a t i o n s u t i l i z e d during the 1984 i n v e s t i g a t i o n . The reasons f o r the s i t e s e l e c t i o n are as f o l l o w s : 1) Westward s l o p i n g topography induces a r e g i o n a l h y d r a u l i c g r a d i e n t t o the west. Water w i l l f l o w down the gradient from recharge areas east of the Main Zone. Much of t h i s water w i l l f l o w towards the Main Zone p i t because the p i t has created a l a r g e trough i n the p h r e a t i c s u r f a c e . Because the east s i d e of the p i t w i l l be recharged c o n t i n u o u s l y from a f a i r l y l a r g e area the water t a b l e i s expected t o remain c l o s e t o surface and w i l l r e s u l t i n high pore pressures and s i g n i f i c a n t amounts of seepage i n t o the p i t . This behaviour i s a l r e a d y being observed and w i l l i n crease as mining progresses t o depth, i n c r e a s i n g the h y d r a u l i c gradient d r i v i n g flow. The west h a l f of the p i t should not have water problems because the g r a d i e n t i s away from the p i t w a l l s i n both d i r e c t i o n s , i n t o the p i t t o the east and down the Bessemer Creek v a l l e y t o the west. Therefore, the west w a l l should e v e n t u a l l y become dry. A l l a c t i v i t y has focused on the east h a l f of the p i t because i t i s the area where the the g r e a t e s t water problems are a n t i c i p a t e d . 2) G e o t e c h n i c a l i n v e s t i g a t i o n s i n d i c a t e t h a t approximately f i v e percent of major d i s c o n t i n u i t i e s observed on the east w a l l have unfavourable o r i e n t a t i o n s t h a t could r e s u l t i n m u l t i p l e berm f a i l u r e s . In t h i s r e p o r t , the term unfavourable i s used t o d e s c r i b e any plane t h a t 54 d a y l i g h t s out of the o v e r a l l p i t slope at an angle that could r e s u l t i n m u l t i p l e berm f a i l u r e or i n the l o s s of a major p o r t i o n of the catchment berm. The magnitude of pore pressure i n the w a l l w i l l s i g n i f i c a n t l y a f f e c t the s t a b i l i t y of any p o t e n t i a l f a i l u r e b l o c k s and must t h e r e f o r e be e s t a b l i s h e d . 3) I n s p e c t i o n of d r i l l core (Colder A s s o c i a t e s , 1983) has i n d i c a t e d t h a t the gabbro i n t r u s i v e complex t h a t i s s i t u a t e d east of the Main Zone may be h i g h l y impermeable and i s u n l i k e l y t o y i e l d l a r g e amounts of discharge i n t o the p i t . In essence, the gabbro i s suspected t o act as a dam. Several d r i l l holes were l o c a t e d i n the gabbro t o con f i r m t h a t the e n t i r e u n i t i s h i g h l y impermeable and no zones of f r a c t u r e d or otherwise pervious m a t e r i a l e x i s t . Other holes were l o c a t e d i n areas th a t are suspected t o provide the p r i n c i p a l flow paths f o r groundwater seepage i n t o the p i t . P e r m e a b i l i t y t e s t i n q i n these holes w i l l a s s i s t i n d e s i g n i n q the most e f f e c t i v e dewatering system t o i n t e r c e p t and remove the water. 4) With the exception of one hole f o r p e r m e a b i l i t y t e s t i n g purposes i n the bottom of the i n t e r i o r p i t , a l l noles were l o c a t e d i n areas where no f u r t n e r mininq a c t i v i t y i s planned. A l l piezometers w i l l t h e r e f o r e be permanent i n s t a l l a t i o n s and can be monitored p e r i o d i c a l l y during the e n t i r e l i f e of the mine. 56 6.2 HYDRAULIC CONDUCTIVITY TESTING 6.2.1 Background H y d r a u l i c c o n d u c t i v i t y i s a rockmass parameter t h a t i n d i c a t e s the r a t e at which water w i l l f l o w through the rockmass under a s p e c i f i e d h y d r a u l i c g r a d i e n t . The s e l e c t i o n and subsequent success of any dewatering scheme i s h i g h l y dependent on the c o e f f i c i e n t of h y d r a u l i c c o n d u c t i v i t y , K. . I f K i s low (e.g. 1.0x10 cm/s) there w i l l be l a r g e r e s i s t a n c e t o water flow toward the w e l l ; t h e r e f o r e , s e l f priming pumps that a u t o m a t i c a l l y t u r n o f f when the water i s drawn near the bottom of the hole w i l l have t o be used t o prevent the w e l l s from being sucked dry. A l s o , the r a d i u s of pumping i n f l u e n c e w i l l be s m a l l . I f K i s l a r g e , (e.g. 1.0x10 3 cir/s) the rockmass i s considered h i g h l y permeable. Water w i l l flow toward the w e l l s e a s i l y and from l a r g e d i s t a n c e s . As a r e s u l t , the drawdown cone w i l l be very broad, but shallow. A very l a r g e area must t h e r e f o r e be dewatered t o drop the water l e v e l i n the w e l l a s i g n i f i c a n t amount. Table 6.1 summarizes the normal range of h y d r a u l i c c o n d u c t i v i t y i n rock and i n d i c a t e s when dewatering can be s u c c e s s f u l . Table 6.1 HYDRAULIC CONDUCTIVITY DEWATERING CONSIDERATIONS Q u a n t i t a t i v e (cm/s) l.OxlO* 4 - 1.0x10** 1.0x10*' - 1.0x10"* l.OxlO - 8 - 1.0x10*° Q u a l i t a t i v e moderate t o high low t o moderate n e a r l y impermeable can be drained e a s i l y by w e l l pumps. can be drained over a p e r i o d of time. cannot be drained by conventional methods. Wells must be under vacuum. 5 7 6.2.2 Method F a l l i n g head p e r m e a b i l i t y t e s t s were used i n the Main Zone t o measure the c o e f f i c i e n t of h y d r a u l i c c o n d u c t i v i t y . The t e s t s were performed i n v e r t i c a l a i r t r a c holes d r i l l e d t o depths of 30 m. Two pneumatic packers, separated by a 3.07 m p e r f o r a t e d pipe were lowered down the hole t o d e s i r e d depth and the assembly was i n f l a t e d , s e a l i n g the t e s t s e c t i o n . Water was then poured i n t o the rod u n t i l the water l e v e l came up t o sur f a c e or a steady s t a t e c o n d i t i o n was a t t a i n e d where water flowed out as q u i c k l y as i t was poured i n . By r a i s i n g the water l e v e l i n the rods an excess pressure head was created i n the t e s t i n t e r v a l . This head induced water flow i n t o the surrounding rock. The r a t e of head d i s s i p i t a t i o n i n the rod once the flow i s shut o f f i s i n d i c a t i v e of the rockmass h y d r a u l i c c o n d u c t i v i t y . This r a t e was p r e c i s e l y monitored by an e l e c t r o n i c water l e v e l probe and recorded. The c o e f f i c i e n t of h y d r a u l i c c o n d u c t i v i t y can be c a l c u l a t e d from the s o l u t i o n of the boundary value problem (B.V.P.) th a t governs the f a l l i n g head t e s t . The s o l u t i o n t o t h i s B.V.P. was f i r s t presented by Hvorslev (1935) and i s de r i v e d i n d e t a i l i n Appendix E. The r e s u l t i n g formula f o r the c a l c u l a t i o n of K i s a l s o shown below: Computer program EQFHEAD was developed t o reduce the time r e q u i r e d t o c a r r y out the Hvorslev a n a l y s i s and increase computational accuracy. The program i s f u l l y documented i n Appendix F. K = r*In(L/R) 2 L To K = h y d r a u l i c c o n d u c t i v i t y r = rad i u s of standpipe L = length of t e s t s e c t i o n R = rad i u s of borehole To= time f a c t o r 58 6.2.3 R e s u l t s The 1984 f a l l i n g head t e s t program was h i g h l y s u c c e s s f u l , d e f i n i n g h y d r a u l i c c o n d u c t i v i t i e s of a l l major rock u n i t s i n the Main Zone. Te s t i n g a l s o showed t h a t b l a s t i n g and s u r f i c i a l weathering have a s i g n i f i c a n t e f f e c t on p e r m e a b i l i t y . Table 6.2 summarizes the f a l l i n g head t e s t r e s u l t s . Table 6.2 R e s u l t s of F a l l i n g Head P e r m e a b i l i t y Tests PIEZOMETER NUMBER TEST SECTION ROCK TYPE K (cm/s) FROM TO (m) P5 10.43 13.50 gabbro 3.0x10** P5 16.57 19.64 gabbro 1.2x10* P5 19.64 22.71 gabbro 2.2X10"1 P6 16.57 19.64 l a p i l l i 6.9x10"* P6 19.64 22.71 l a p i l l i 2.9xl0' 5 P6 22.71 25.78 l a p i l l i 4.3xl0" S P7 16.57 19.64 gabbro 1.7x10"* P7 22.71 25.78 gabbro 9.6x10"* P8 19.64 22.71 gabbro 2.9xl0" 7 P8 22.71 25.78 gabbro 2.2X10"4 KI 7.36 10.31 l a p i l l i 1.3x10** K2 22.71 25.78 dust t u f f 1.2xl0" 5 K2 25.78 28.85 dust t u f f 7.7x10"' K2 31.92 34.99 dust t u f f 2.5x10"' Because the a i r t r a c i s a percussion d r i l l , a l a r g e amount of f i n e c u t t i n g s are generated during d r i l l i n g . Compressed a i r i s then c i r c u l a t e d down the d r i l l rod t o f l u s h the c u t t i n g s out of the hole through the sm a l l clearance between the d r i l l rod and the w a l l of the d r i l l h o l e . Some of the c u t t i n g s are fo r c e d i n t o any open cracks and f i s s u r e s i n the d r i l l h ole. As a d i r e c t r e s u l t , h y d r a u l i c c o n d u c t i v i t i e s measured i n a i r t r a c holes are g e n e r a l l y lower than the t r u e value. Therefore, average values of K f o r each rock u n i t that were obtained from f a l l i n g head t e s t s i n a i r t r a c holes have been m u l t i p l i e d by a f a c t o r of 5 t o account f o r the a r t i f i c i a l decrease i n rock mass 59 p e r m e a b i l i t y . P e r m e a b i l i t y t e s t s i n hole K2 were not c o r r e c t e d because K2 i s an o l d v e r t i c a l diamond d r i l l h o l e , and should not be clogged by c u t t i n g s t o the same degree. The average, c o r r e c t e d values of h y d r a u l i c c o n d u c t i v i t y are l i s t e d i n Table 6.3. They are the best a v a i l a b l e estimates of K, and should be used f o r a l l subsequent i n v e s t i g a t i o n s . Table 6.3 Representative Values f o r H y d r a u l i c C o n d u c t i v i t y ROCKTYPE CONDITION K (cm/s) Gabbro Gabbro L a p i l l i T u f f L a p i l l i Tuff Dust Tu f f i n t a c t b l a s t e d or weathered i n t a c t b l a s t e d or weathered i n t a c t 2.0x10"' 2.0x10 2.0x10"* 1.0x10 7.0x10'' The h y d r a u l i c c o n d u c t i v i t i e s obtained i n the 1984 t e s t i n g correspond c l o s e l y t o r e s u l t s from e a r l i e r t e s t s i n the v i c i n i t y of the Main Zone (Golder A s s o c i a t e s , 1983) and i n the Southern T a i l p i t (Beaudoin, 1981). R e s u l t s of the e a r l i e r t e s t s are t a b u l a t e d i n Appendix H.3. Table 6.4 i n d i c a t e s the normal range of p e r m e a b i l i t i e s t h a t can be expected f o r s p e c i f i c rock types. The t e s t r e s u l t s a l s o c o r r e l a t e w e l l w i t h these q u i d e l i n e s . The p e r m e a b i l i t y t e s t i n g program has confirmed t h a t the gabbro i s n e a r l y impermeable while the v o l c a n i c s have a moderately high K. Wi t h i n 10 t o 20 m of production b l a s t s the h y d r a u l i c c o n d u c t i v i t y of a l l rock u n i t s i n c r e a s e s , p o s s i b l y by as much as two orders of magnitude. The i n c r e a s e can be d i r e c t l y a t t r i b u t e d t o f r a c t u r i n g of the rockmass and opening of healed or gouge f i l l e d j o i n t s that occurs c l o s e t o the b l a s t e d area. Dewatering of the Main zone p i t should be p o s s i b l e as 60 h y d r a u l i c c o n d u c t i v i t i e s i n the v o l c a n i c s are s u f f i c i e n t l y high t o a l l o w f l o w towards the w e l l s . A p r e l i m i n a r y e v a l u a t i o n of dewatering p o t e n t i a l i n the Main Zone i s presented i n S e c t i o n 6.6. Table 6.4 Normal Range of P e r m e a b i l i t i e s i n S o i l and Rock ( a f t e r Freeze, 1979) R o c K i 01 ' c = o a .£ o> . ! o x JC w 3 O 0> Q i n . «< y .K -•"8 D O o B E 2-22 T3 -O C o Unconsol idated deposits > o C I 0) >. u : uo •o D O " w U U lis? I 0 Ol 01 c 5 1 (dorcy) (cm 2 ) r i O ' I04 10s 10* 10 I 10' 10 10' 10-* l O ' 9 10"* l O ' 7 l O ' " 10"3 IO" 4 l O " 5 - I O " 6 io-7 io-« 10"' l-io-'0 -2 10" 10 -12 10' K (cm/s) ( r I O -10 -1 10 h 10 I O " 3 -io-4 - I O " ' io-« r-10-7 IO'8 10"" -10 -10 •is 10" m/s) (gol/doy/tr) 1 h io-10 1- 10" 10"s -10" 10 L I 0 " -io rt0 e 10" - s -10s ICT 10" to--10" , ho3 102 10 1 10 10" -10" .-10 L-IO •IS -10" 10 -2 10' 10 -10" 10" 10" -4 61 6.3 PIEZOMETER MONITORING Fourteen standpipe piezometers have been installed in the east half of the Main Zone pi t to provide information on pore pressures in the pit walls. Piezometers Pi to P4, completed by Golder Associates in 1983, were monitored weekly during the spring and summer to determine seasonal fluctuations in pore pressures. Ten additional piezometers were installed in late August, 1984 in key areas of the p i t . Appendix J summarizes existing piezometer information including: 1. method of installation, 2. location, and 3. monitoring records. The highest water levels, within 6 m of surface, were observed in the south end of the p i t . Water levels in the east wall, south of Bessemer Creek ranged from 10 to 20 m below surface. Above the Gabbro pit the water levels were relatively low, from 15 m below surface in P 10 to more than 27 m in P 14, as the hole remains dry. In summary, the water table generally follows topography, but is found deeper below suface from south to north. It is also found at shallower depth below surface as elevation is decreased in any given section, from 10 to 20 m below surface at the top of the pit to zero near the p i t floor. There, seepage occurs so the water table must be at the surface. Weekly monitoring of Pi to P4 has indicated that there is a strong seasonal fluctuation in pore pressure. Figure 6.2 summarizes the monitoring records in a graph of water level vs. time. The highest levels in each of the piezometers were observed in late May, then gradually decreased in June and July. By early August the levels were once again rising and have continued to increase slowly to date. The maximum seasonal fluctuation appears to be about 10 m. There does not appear to be a correlation between short term climatic events and 62 0 P4 © Q . . . "O. FIGURE 6-2 PIEZOMETER MONITORING the water l e v e l s . piezometers P i t o P3 are nested i n a s i n g l e bore hole south of the Gabbro p i t . The v e r t i c a l component of the h y d r a u l i c gradient has g e n e r a l l y been upward. Gradients as high as 0.15 m/m were observed between P i at 148 m and P2 at 67 m. This response i n d i c a t e s that there may be s i g n i f i c a n t amounts of flow of water toward the p i t from depth, as w e l l as the expected drainage of groundwater from the h i l l s above the Main Zone. 64 6.4 INTERPRETATION OF MAIN ZONE HYDROLOGY Groundwater flow patterns in the Main Zone are influenced by geology, topography and the presence of the open p i t . The recharge area that drains toward the pit is outlined in Figure 6.3. Most of the surface runoff is diverted away from the p i t , but groundwater flow is not impeded. Steady state groundwater inflow into the Main Zone pit is estimated at 1.27x10 m /s (Golder Associates, 1983). A flownet (Figure 6.4) shows the li k e l y flow pattern in vertical section. The majority of groundwater that drains into the pit originates east of the Main zone. As much as 30% of the water may be flowing into the pit from below the p i t floor under an upward hydraulic gradient. This upward flow has been observed at depth in the southern portion of the Main Zone in piezometers Pi to P3 and must be considered in the design of the pit dewatering system. The permeability testing program has confirmed that the gabbro intrusive complex east of the Main zone is nearly impermeable. I t acts as a barrier to groundwater recharge. The majority of groundwater inflow must occur through the volcanic rocks, found in the south end of the Main Zone and in the east wall of the Gabbro Pit. Whether a significant amount of water flows through the highly fractured rocks in the vi c i n i t y of Bessemer Creek remains to be established. Figure 6.5, a plan of the Main zone p i t , shows the location of the principal flowpaths discharging into the p i t . 65 N O T E ' N U M K I V O CONTOURS M i E O U I P O T E N T M L J 66 The gabbro tongue i s expected t o have some i n f l u e n c e on r a t e s of i n f l o w of groundwater i n t o the p i t and on pore pressures i n the east u l t i m a t e p i t w a l l i n the area of the e x i s t i n g gabbro p i t . Because of the low p e r m e a b i l i t y , the gabbro tongue w i l l a c t as a dam, preventing drainage of the more pervious p y r o c l a s t i c s i n the "notch" between the tongue and the main gabbro p l u t o n . However, because the p y r o c l a s t i c s w i t h i n the notch are surrounded on three s i d e s by low p e r m e a b i l i t y gabbro, recharge i n t o the area w i l l be slow i n the short term, provided precautions are taken t o ensure t h a t a l l s u r f a c e runoff i s prevented from seeping i n t o the area ( i . e . no seepage i s occuring from the Bessemer Creek d i v e r s i o n ) . Water that does enter the notch can l i k e l y d r a i n s u f f i c i e n t l y f a s t through the gabbro tongue or southward around i t . Piezometers l o c a t e d i n the p y r o c l a s t i c s w i t h i n the notch i n d i c a t e t h a t adequate drainage i s occuring as pressures are q u i t e low, some piezometers remain dry. When mining i n the gabbro p i t progresses t o greater depth the g r a d i e n t i n the notch w i l l become f a i r l y steep toward the south and l a r g e r q u a n t i t i e s of water can be expected t o flo w toward the p i t from the vast area of p y r o c l a s t i c s s i t u a t e d north of the tongue. As a p r e c a u t i o n , piezometers should be completed i n the p y r o c l a s t i c s behind the dam as mining progresses t o depth. I f these piezometers are i n d i c a t i n g high pressures then h o r i z o n t a l d r a i n s should be i n s t a l l e d t o bleed them o f f . Figure 6.6 i s an i l l u s t r a t i o n of the a n t i c i p a t e d h y d r o l o g i c problem. 68 V i s i b l e seepage on south w a l l s of the i n t e r i o r p i t and lack of such seeps i n the gabbro Confirms that much more water i s f l o w i n g i n the v o l c a n i c s . Most of the seeps occur adjacent t o dykes, f a u l t s , and shears. The gouge zones a s s o c i a t e d w i t h these major d i s c o n t i n u i t i e s have a high c l a y content; t h e r e f o r e , they act as impervious membranes. Because water cannot penetrate these planar s t r u c t u r e s i t i s fo r c e d t o flow along them. A seep i s created wherever these s t r u c t u r e s d a y l i g h t . The rock d i r e c t l y adjacent t o the d i s c o n t i n u i t y may a l s o be more f r a c t u r e d by t e c t o n i c a c t i v i t y , p r o v i d i n g a flo w path o f l e s s r e s i s t a n c e . The i n f l u e n c e of these major s t r u c t u r e s on p i t dewatering must be considered i n the design. The s t r u c t u r e s may i s o l a t e groundwater i n t o s t r u c t u r a l l y bounded blocks that cannot be dewatered unless the pumping w e l l s are l o c a t e d d i r e c t l y w i t h i n the b l o c k s . Such a s i t u a t i o n was r e c e n t l y experienced at G i b r a l t a r Mines (Carpenter, 1980). GABBRO s l o w r a t e s o f r e c h a r g e PYROCLASTIC NOTCH h i g h K ' i n s t a l l p i e z o m e t e r s , a n d d r a i n a g e If w a r r a n t e d G A B B R O T O N G U E D A M FIGURE 6 - 6 69 6.5 SURFACE RUNOFF Two d i v e r s i o n d i t c h e s capture the m a j o r i t y of surface r u n - o f f f l o w i n g toward the Main Zone p i t from the eastern h i l l s i d e . Bessemer Creek i s d i v e r t e d t o the south along a d i t c h that a l s o i n t e r c e p t s a l l r u n - o f f south of the creek bed. A second d i t c h , s t a r t i n g at the base of the Bessemer Creek d i v e r s i o n dam and d r a i n i n g n o r t h , i s c u r r e n t l y under c o n s t r u c t i o n . When completed, t h i s d i t c h w i l l d i v e r t any flows north of the creek bed. To complete t h i s d i t c h , o b s t r u c t i o n s b l a s t e d t h i s summer must be mucked out and areas where bedrock i s exposed should be l i n e d w i t h compacted g l a c i a l t i l l t o prevent seepage. During times of heavy r a i n f a l l a flow of approximately 50 1/min develops down the o l d Bessemer Creek bed downstream of the d i v e r s i o n dam. The water discharges i n t o the p i t a t 1320 m e l e v a t i o n . The flo w o r i g i n a t e s as seepage through the d i v e r s i o n dam and as groundwater discharge. Near the d i v e r s i o n dam, most of the seepage water i s f l o w i n g below ground so i t i s not i n t e r c e p t e d by the north d i v e r s i o n d i t c h . To prevent the water from seeping i n t o the p i t a catchment dam and d i v e r s i o n system w i l l be re q u i r e d near the p i t c r e s t . A sketch of the problem areas and suggested improvements i s presented i n Figure 6.7. 70 FIGURE 6-7 RUN-OFF CONTROL 71 6.6 CONSIDERATIONS FOR PIT DEWATERING 6.6.1 Background The f a l l i n g head p e r m e a b i l i t y t e s t i n g program has e s t a b l i s h e d the magnitude of the h y d r a u l i c c o n d u c t i v i t y c o e f f i c i e n t f o r each g e o l o g i c u n i t . Experience suggests that the v o l c a n i c rocks can be dewatered e f f e c t i v e l y as t h e i r K i s f a i r l y h i g h . The gabbro, e s p e c i a l l y when i n t a c t , w i l l r e q u i r e numerous c l o s e l y spaced w e l l s i f dewatering i s t o be s u c c e s s f u l . The purpose of t h i s s e c t i o n i s t o explore i n greater d e t a i l how the c o n t r o l l i n g h y d r o l o g i c parameters ( h y d r a u l i c c o n d u c t i v i t y , a q u i f e r t h i c k n e s s , s p e c i f i c y i e l d , and pumping rate) i n f l u e n c e the performance of the dewatering systems. By studying the shape of the drawdown cone about a pumping w e l l and the r a t e of drawdown as one parameter i s v a r i e d while the others are h e l d constant the most i n f l u e n t i a l parameters can be i d e n t i f i e d . Further work can then focus on those important parameters while the l e s s i n f l u e n t i a l parameters can be estimated i n the a n a l y s i s without s e r i o u s l y a f f e c t i n g the v a l i d i t y of the r e s u l t s . The second p a r t of t h i s s e c t i o n presents the "most l i k e l y " model of drawdown behaviour that can be expected i n the Main Zone i f i n - p i t w e l l s are s e l e c t e d as the dewatering system. This s i m u l a t i o n provides a rough idea of the pumping r a t e s , w e l l depths, and spacings t h a t w i l l be r e q u i r e d t o a t t a i n the d e s i r e d goal of reducing the i n f l o w s i n t o d r i l l holes t o l e v e l s where most holes can be loaded w i t h ANFO, provided the holes are f i r s t pumped dry, then l i n e d w i t h a waterproof membrane. A computer program was developed t o simulate the behaviour of a s i n g l e pumping w e l l dewatering an unconfined a q u i f e r . The program i s based on the Theis S o l u t i o n , an a n a l y t i c a l s o l u t i o n to the s i n g l e 72 pumping w e l l boundary value problem. T h e o r e t i c a l concepts of the Theis S o l u t i o n and the procedures used t o evaluate the mathematically complex equations are presented i n d e t a i l i n Appendix I . The t h i r d p a r t of t h i s s e c t i o n b r i e f l y discusses the various systems t h a t could be used f o r dewatering, i n c l u d i n g the advantages and f a u l t s of each. 6.6.2 S e n s i t i v i t y Study The s e n s i t i v i t y study c o n s i s t e d of four p a r t s . During each p a r t one parameter was v a r i e d while the remaining three were he l d constant at reasonable values. Three or four d i f f e r e n t magnitudes spanning the expected range of the parameter were entered i n t o the s i m u l a t i o n . R e s u l t s f o r each s i m u l a t i o n are t a b u l a t e d i n Appendix K. To a i d i n i n t e r p r e t a t i o n , one s p e c i f i c time was s e l e c t e d during each s i m u l a t i o n and the drawdown curves f o r each value of the v a r i a b l e parameter were drawn. The spread of the curves i s a d i r e c t i n d i c a t i o n of the s e n s i t i v i t y of the system t o that p a r t i c u l a r v a r i a b l e . 6.6.2.1 H y d r a u l i c C o n d u c t i v i t y H y d r a u l i c c o n d u c t i v i t y i s a very important parameter because i f K i s too low the rock cannot be s u c c e s s f u l l y dewatered, no matter what pumping r a t e i s used. This i s c l e a r l y evident i n Figure 6.8. The two low K s i m u l a t i o n s (K=lxlO & 1x10 cm/s) have very t i g h t cones about the w e l l w h i l e the high K cones are very e x t e n s i v e but shallow. This behaviour can be understood by c o n s i d e r i n g h y d r a u l i c c o n d u c t i v i t y as a q u a n t i t a t i v e measure of r e s i s t a n c e t o flow. I f K i s high water flows e a s i l y so i t can flow from great d i s t a n c e s under a low g r a d i e n t ; hence, the cone i s broad but shallow. When K i s low there i s a l o t 73 HEIGHT (m) 100 so 60 70 60 50 40 30 20 10 0 0 3 10 20 1.0 » IO*4 cm/« L 0 - IO*5 • 1.0 - IO*6 • i.o i id . 7 • so 100 DISTANCE FROM WELL (m) TIME THICKNESS SPECIFIC YIELD PUMPING RATE LiZiia. 00 days 50.00 ni 0. 05 10.00 1/niin 200 FIGURE 6-8 INFLUENCE OF HYDRAULIC CONDUCTIVITY of r e s i s t a n c e t o flow. Water has a hard time f l o w i n g any d i s t a n c e . Any water c l o s e t o the w e l l i s removed f i r s t and a very steep cone i s e s t a b l i s h e d . The h y d r a u l i c gradient toward the w e l l i s very high. -6 Figure 6.8 confirms t h a t rocks w i t h K smaller than 1x10 cm/s cannot be dewatered e a s i l y because even at the very low pumping r a t e of 10 1/min the w e l l i s q u i c k l y pumped dry and an e q u i l i b r i u m c o n d i t i o n i s developed w i t h a radius of i n f l u e n c e of only 10 m. Although the depth of the high K drawdown cone i n Figure 6.8 appears too shallow t o j u s t i f y dewatering, i t must be remembered that i f the pumping r a t e i s increased the cone w i l l become much deeper. 6.6.2.2 Aq u i f e r Thickness A q u i f e r t h i c k n e s s can a f f e c t the s i z e of the drawdown cone co n s i d e r a b l y i f i t i s allowed t o vary over a l a r g e range. However, at E q u i t y , i t i s very l i k e l y t hat the " a q u i f e r " c o n s i s t s of the a r t i f i c i a l l y f r a c t u r e d rocks that extend from surface t o a depth of 10 t o 20 m. Because there i s not much d i f f e r e n c e i n the s i z e of the drawdown cone over t h i s range of t , t h i c k n e s s i s not a h i g h l y i n f l u e n t i a l v a r i a b l e . In the Theis a n a l y s i s , the s o l u t i o n i s developed i n terms of the parameter " t r a n s m i s s i v i t y " , which i s the product of h y d r a u l i c c o n d u c t i v i t y and t h i c k n e s s . When one considers t h a t the range i n K i s three or four orders of magnitude w h i l e t h i c k n e s s most l i k e l y v a r i e s by a f a c t o r of f i v e , i t becomes obvious t h a t i t i s much more important t o get a v a l i d value f o r the parameter K then t o a c c u r a t e l y d e f i n e t h i c k n e s s . 75 - J 80 70 60 HEIGHT (m) 5 0 40 30 20 10 o a to 10 m 20 • 50 • 100 20 50 100 200 DISTANCE FROM WELL (m) TIME PUMPING RATE HYDRP.UIC COND. SPECIFIC YIELD = 11300.30 days = 10.00 l/min = 1.00 x 0. 05 F IGURE 6 - 9 INFLUENCE OF AQUIFER THICKNESS 10*S cm/s 6.6.2.3 S p e c i f i c Y i e l d S p e c i f i c y i e l d i s synonymous t o s t o r a t i v i t y i n the case of a con f i n e d a q u i f e r . The parameter s p e c i f i e s the volume of water that w i l l be re l e a s e d from storage over a u n i t area of a q u i f e r f o r a u n i t d e c l i n e i n the water t a b l e . Hence, the parameter i s dimmensionless. In p r a c t i c a l terms, s p e c i f i c y i e l d i s r e a l l y an i n d i c a t o r of p o r o s i t y , because when the water t a b l e i s lowered most water that d r a i n s comes d i r e c t l y from the pores, w h i l e much smaller amounts are generated by expansion of the water due t o reduced pressure and expansion of the rock i n t o the pore space. Therefore, s p e c i f i c y i e l d has a f a i r l y narrow range, from 0.01 t o 0.30. In the f r a c t u r e d rocks w i t h i n the fragmented zone the p o r o s i t y i s expected t o be about 0.05. S p e c i f i c y i e l d i s the l e a s t s e n s i t i v e parameter. The curves from the four s i m u l a t i o n s spanning the expected range of SY a l l f i t w i t h i n a very narrow envelope. Therefore, i t i s v a l i d t o s e l e c t a reasonable estimate of SY f o r the s i m u l a t i o n s and focus on accurate d e f i n i t i o n of h y d r a u l i c c o n d u c t i v i t y K. 6.6.2.4 Pumping Rate U n l i k e the h y d r o l o g i c v a r i a b l e s , pumping r a t e i s a parameter t h a t can be c o n t r o l l e d . Figure 6.11 i n d i c a t e s t h a t the s i z e of the drawdown cone and r a t e of dewatering can be c o n t r o l l e d by the r a t e of pumping. In g e n e r a l , the l a r g e r the pumping r a t e , the more extensive and deeper w i l l be the drawdown cone. However, i t can a l s o be seen i n Figure 6.11 th a t i f an e x c e s s i v e l y l a r g e pumping r a t e i s used the w e l l w i l l q u i c k l y be pumped dry. This type of problem was encountered at G i b r a l t a r Mines 77 FIGURE 6-10 TIME = 1 0 0 0 . 0 0 days THICKNESS = 5 0 . 0 0 m INFLUENCE OF SPECIFIC YIELD HYDRAUIC COND. = 1 .00 x 1 0 5 cm/s PUMPING RATE = 1 0 . 0 0 1/min FIGURE 6-11 TIME = 1 0 0 0 . 0 0 days INFLUENCE OF PUMPING RATE THICKNESS = 50.80 m HYDRAUIC COND. = 1.00 x 10 cm/s SPECIFIC YIELD = 0.05 where i t was overcome by i n s t a l l i n g l i m i t switches i n the w e l l s so the pumps a u t o m a t i c a l l y stopped when the water l e v e l i n the w e l l reached a s p e c i f i e d c u t - o f f p o i n t . 6.6.2.5 Most L i k e l y S i m u l a t i o n A h y d r a u l i c c o n d u c t i v i t y value of 1.0x10 cm/s was s e l e c t e d as the r e p r e s e n t a t i v e K because i t i s intermediate between the f r a c t u r e d K f o r l a p i l l i t u f f s as.measured near the surface and the i n t a c t K value f o r the same rock u n i t t h a t was averaged over s e v e r a l measurements at depth. The a q u i f e r t h i c k n e s s was assumed t o be 30 m. This estimate i s co n s e r v a t i v e because a th i n n e r a q u i f e r has a deeper drawdown cone so more pumping w i l l be r e q u i r e d t o get the d e s i r e d water t a b l e drawdown w i t h the t h i c k e r a q u i f e r . A s p e c i f i c y i e l d of 0.05 was chosen as r e p r e s e n t a t i v e of the f r a c t u r e d rock. The only v a r i a b l e that s t i l l r e q u i r e d s e l e c t i o n was the pumping r a t e . A f t e r s e v e r a l t r i a l s i t was discovered t h a t f o r the f a i r l y high K value s e l e c t e d a very l a r g e pumping r a t e would have t o be used t o achieve a reasonably s i z e d drawdown cone. A pumping r a t e of 100 1/min was input i n t o the program. With the above parameters a d e s i r a b l e drawdown was achieved a f t e r about 200 days. Figure 6.12 i l l u s t r a t e s the simulated drawdown a f t e r 500 days w i t h a l l v a r i a b l e s set t o the above mentioned values. By using the p r i n c i p l e of s u p e r p o s i t i o n that s t a t e s drawdowns from two i n d i v i d u a l w e l l s can simply be added together t o o b t a i n the r e s u l t a n t , a composite drawdown curve was constructed f o r two w e l l s spaced 100 m apart. The net drawdown exceeds 30 m everywhere between the two 80 pumping wells so i t i s l i k e l y that a lower pumping rate of 50 to 75 1/min could adequately dewater the f r a c t u r e d a q u i f e r . — CM d zi LU Ul O UJ u_ u. U J Q UJ z CD 2 O o 8 8 o 8 o i s I ? 8 ^ CM UJ it o ot z to o z O H S z o u z o Q I tr • to Q U i H U UJ CL X UJ Ul T3 <S i3 © S 1 . • . <S Q 11 11 11 11 . o a _j Z LU a •-• u > in CO CJ CJ LLi t - H t—< Z D U . ac a n LU u rr u E w Q U J •-» x > a 1— 1— X cn o CM 81 6.7 DEWATERING SYSTEMS In t h i s s e c t i o n s i x p o s s i b l e dewatering systems are presented and the advantages and f a u l t s of each system are l i s t e d i n p o i n t form. The methods are: 1. e x i s t i n g sump method 2. modified sump trench 3. p i t perimeter w e l l s 4. i n - p i t w e l l p o i n t system 5. h o r i z o n t a l d r a i n s 6. s e l f d r a i n i n g w e l l s 6.7.1 E x i s t i n g Sump Method The sump method c o n s i s t s of a s i n g l e submersible pump tha t i s placed i n a sump excavated s e v e r a l meters below the p i t f l o o r . Water i s pumped through a t h i c k pipe t o the t a i l i n g s area. A second, and and perhaps t h i r d sump could be excavated so a drainage channel does not have t o be maintained on the p i t f l o o r t o c o l l e c t water and d i r e c t i t t o the sump. Advantages 1. R e l a t i v e l y inexpensive. 2. Easy t o maintain. 3. Very mobile. 4. Easy t o i n s t a l l . 5. A c c e s s i b l e . 6. Works i n any rock c o n d i t i o n . Disadvantages 1. Water l e v e l remains near s u r f a c e . 2. S l u r r y e x p l o s i v e s o f t e n r e q u i r e d . 3. pore pressures i n w a l l remain h i g h . 4. In production areas, gets i n way. 82 6.7.2 Modified Sump Trench A simple alternative to the sump method that could decrease the amount of slurry explosives used would be to always start the sinking cut of a new bench in an area of high water inflow, e.g. the south east side. In this way the principal flow paths of water into the p i t would be intercepted. The p i t floor would progressively become dryer as water that was present in the rock would drain off. Advantages 1. Relatively inexpensive. 2. Easy to maintain. 3. Works in any rock condition. 4. Accessible. Disadvantages 1. Not thoroughly tested. 2. pore pressures in wall remain high. 3. Affects mining sequence on bench. 4. Water level w i l l not be pulled down sufficiently to make a l l holes dry. 6.7.3 Pit Perimeter Wells Deep pumping wells could be installed around the pit perimeter, The wells would have downhole submersible pumps capable of pumping under very high pressure head. Advantages 1. Permanent installation. 2. Minimal maintenance required. 3. A l l equipment out of the way. 4. Water would be drawn far away from pit wall, s t a b i l i t y would be increased. 5. Water table in bottom of pit could be drawn down adequately i f K sufficiently high. 6. Slurry explosives would be required in far fewer holes. Disadvantages 1. Expensive to i n s t a l l . 2. Wells may have to be spaced, f a i r l y closely (e.g. 20-50 m). to attain sufficient drawdowns. 3. Very large cone would have to be dewatered to pull down W.T. 4. May not work in gabbro as permeability simply too low. 5. Specialized d r i l l required for installation of deep wells. 6. Large energy consumption expense. 83 6.7.4 I n - P i t W ell P o i n t System The i n - p i t w e l l p o i n t dewatering system i s probably the most e f f e c t i v e way of drawing the water t a b l e down t o a s u f f i c i e n t depth t o a l l o w f o r the use of ANFO e x p l o s i v e s i n most d r i l l h oles. Nine inc h diameter holes c o u l d be d r i l l e d t o a depth of 30 m with the production d r i l l s . Submersible pumps cou l d then be lowered i n t o the holes. The w e l l s should be l o c a t e d along ramps so that they would remain a c c e s s i b l e f o r maintenance and eventual r e l o c a t i o n once mining progressed t o the l e v e l of the w e l l p o i n t s . Advantages Disadvantages 1. R e l a t i v e l y s m a l l area has t o be 1. pumps have t o be r e l o c a t e d i n dewatered. Less water produced. new w e l l s as mining progresses. 2. I n s t a l l a t i o n and s e r v i c e can 2. Water l i n e s i n p i t may get i n be performed by Equity s t a f f way or get damaged. and equipment. 3. Pumps w i l l be high cost items. 3. B e n e f i c i a l e f f e c t on w a l l 4. F a i r l y labour i n t e s i v e method, s t a b i l i t y , but l e s s than p e r i p h e r a l pumps. 4. System more f l e x i b l e than p e r i p h e r a l pumps. 5. Less w e l l s r e q u i r e d f o r equal coverage. 84 6.7.5 H o r i z o n t a l Drains H o r i z o n t a l d r a i n s are without doubt the s i n g l e most e f f e c t i v e and e f f i c i e n t method of groundwater c o n t r o l f o r w a l l s t a b i l i t y . When p r o p e r l y i n s t a l l e d , the d r a i n s reduce the pore pressures i n the p i t w a l l s s u f f i c i e n t l y t o have a very dramatic increase on s t a b i l i t y . I n s t a l l a t i o n of the d r a i n s i s expensive as a s p e c i a l i z e d d r i l l r i g i s r e q u i r e d t o o b t a i n a s u f f i c i e n t depth of p e n e t r a t i o n (the Aardvark system from S e a t t l e has an e x c e l l e n t t r a c k record and should be considered during the c o n t r a c t b i d p r o c e s s ) . However, because down hole pumps are not r e q u i r e d , the i n i t i a l investment i s c o n s i d e r a b l y lower than e q u i v a l e n t drainage w i t h v e r t i c a l pumping w e l l s . In the long term, h o r i z o n t a l d r a i n s become even more l u c r a t i v e because operating c o s t s are very low as the only pumping re q u i r e d i s the removal of water from a c e n t r a l c o l l e c t i o n sump. To increase the i n i t i a l e f f e c t i v e n e s s of the drainage system i n rocks of low p e r m e a b i l i t y , a s e a l can be developed i n the outer 5-10 m and the e n t i r e d r a i n p l a c e d under vacuum. Advantages Disadvantages 1. R e l a t i v e l y inexpensive t o 1. Does not draw water t a b l e below i n s t a l l . p i t f l o o r . Requirements f o r 2. Improves w a l l s t a b i l i t y by s l u r r y based e x p l o s i v e s remain, reducing pore pressures. 2. S p e c i a l i z e d c o n t r a c t o r r e q u i r e d 3. Very economic i n long term as f o r i n s t a l l a t i o n . pumping and maintenance c o s t s 3. Water must be c o l l e c t e d at f a c e , nominal. c o l l e c t i o n system i n way of oper a t i o n s . 85 6.7.6 G r a v i t y Well Method The g r a v i t y w e l l method posseses many of the favourable a t t r i b u t e s of both the i n - p i t w e l l s and the h o r i z o n t a l d r a i n s . The method c o n s i s t s of v e r t i c a l , 9" diameter h o l e s , d r i l l e d t o maximum depth with the 40-R production d r i l l s . The holes are then b a c k f i l l e d w i t h a high p e r m e a b i l i t y coarse sand t o keep them from caving. H o r i z o n t a l d r a i n s are d r i l l e d p r e c i s e l y t o i n t e r c e p t the base of the v e r t i c a l w e l l s , p r o v i d i n g a flow path by which water can escape t o s u r f a c e . The d r a i n s must be l i n e d , and only the inner two t h i r d s of the c a s i n g p e r f o r a t e d . Experience at Highland Uranium Mines i n Wyoming has shown that approximately 50% of the d r a i n s s u c c e s s f u l l y i n t e r c e p t the v e r t i c a l h o l e s . To ensure an adequate flow path between the w e l l s and d r a i n s i n a l l h o l e s , a small e x p l o s i v e charge (5-10 kg) can be detonated t o f r a c t u r e the rock at the s i t e of i n t e r s e c t i o n . Because a much l a r g e r s i n k of atmospheric pressure i s introduced w e l l behind the p i t w a l l then would be the case w i t h h o r i z o n t a l d r a i n s , dewatering w i l l be much more r a p i d . This i s h i g h l y advantageous at E q u i t y , where h y d r a u l i c c o n d u c t i v i t i e s are q u i t e low, e s p e c i a l l y i n the i n t a c t rock at depth. As w i t h the h o r i z o n t a l d r a i n s , o p e r a t i n g c o s t s of t h i s system are again very low because of nominal pumping and maintenance c o s t s . Advantages Disadvantages 1. Drainage by g r a v i t y , no pumps 1. Does not f u l l y dewater p i t . i n w e l l s . 2. Requires s p e c i a l i z e d equipment 2. Larger area of i n f l u e n c e than w i t h f o r d r i l l i n g of d r a i n s , c o n v e n t i o n a l h o r i z o n t a l d r a i n s . 3. High degree of p r e c i s i o n 3. Major r e d u c t i o n i n pore pressures r e q u i r e d f o r s u c c e s s f u l leads t o increased w a l l s t a b i l i t y . i n s t a l l a t i o n . 4. Most work can be c a r r i e d out by 4. Water t a b l e not p u l l e d below Equity s t a f f and equipment. p i t f l o o r . 5. C o l l e c t i o n system i n way of p i t o perations. 86 6.7.7 System E v a l u a t i o n Of the s i x systems introduced i n t h i s report i n p i t w e l l s and g r a v i t y d r a i n s have the g r e a t e s t p o t e n t i a l f o r improving the ground-water s i t u a t i o n i n the Main Zone and should be s t u d i e d i n f u r t h e r d e t a i l . The p i t sump methods have no i n f l u e n c e on w a l l s t a b i l i t y and very l i t t l e i n f l u e n c e on the i n f l o w of water i n t o b l a s t h o l e s ; t h e r e f o r e , i n c r e a s i n g problems w i t h b l a s t i n g and w a l l s t a b i l i t y can be expected as mining progresses t o depth i f these methods of drainage are s e l e c t e d . Because of the r e l a t i v e l y low p e r m e a b i l i t y of the i n t a c t rock i n the Main Zone deep w e l l s would have t o be spaced very c l o s e l y together t o achieve the d e s i r e d r a t e of drawdown. Even then,-the drawdown cone would be q u i t e steep and narrow so very l i t t l e drainage would occur from the p i t f l o o r . I n - p i t w e l l s w i l l drawdown the water t a b l e on the p i t f l o o r t o a l l o w f o r increased use of ANFO. However, pore pressures i n the p i t w a l l s w i l l not be reduced s i g n i f i c a n t l y i f pumping w e l l s are l o c a t e d only on the bottom of the p i t . Therefore, groundwater w i l l continue t o have a strong d e s t a b i l i z i n g i n f l u e n c e on any p o t e n t i a l f a i l u r e s . The g r a v i t y drainage system would reduce pore pressures i n the p i t w a l l s t o a favourable l e v e l at minimum expense. But t h i s system does not have the c a p a c i t y t o p u l l the water t a b l e down below the p i t f l o o r t o i n c r e a s e the number of dry b l a s t h o l e s . The optimum drainage system i n the Main Zone should have the c a p a c i t y t o achieve both a r e d u c t i o n i n pore pressure i n the w a l l s and drawdown the water t a b l e on the p i t f l o o r . With c a r e f u l l y planned drainage design t h i s goal can be achieved. The recommended system 87 would c o n s i s t of 30 m deep w e l l s l o c a t e d on the p i t f l o o r . These would be pumped t o draw down the water t a b l e p r i o r t o d r i l l i n g of production b l a s t h o l e s . Then, as mining progressed down another 30 m, a new set of w e l l s would again be completed on the p i t f l o o r . At the same time, the o l d w e l l s could be i n t e r c e p t e d by h o r i z o n t a l d r a i n s t o form g r a v i t y d r a i n s . These would continue t o d r a i n the p i t w a l l s and maintain pore pressures at very favourable l e v e l s . The proposed WIP/GraD system (Wells In P i t / GRAvity Drainage) i s i l l u s t r a t e d i n Figure 6.13. Note t h a t i f 20 m high double benches are used i n the area t o be dewatered then the system w i l l have t o be modified t o maintain access t o both the top of the w e l l ( r e q u i r e d during pumping stage) and t o the h o r i z o n t a l d r a i n s ( f o r maintenance of water c o l l e c t i o n system). The options are: 1) i n t e r c e p t w e l l s at 20 m depth from every double bench, 2) d r i l l h o r i z o n t a l d r a i n i n c l i n e d at 12* from 40 m below the w e l l c o l l a r , and 3) d r i l l 40 m deep w e l l and i n t e r c e p t with h o r i z o n t a l d r a i n . Option 3 i s the optimum t e c h n i c a l s o l u t i o n because i t d r a i n s the l a r g e s t area of the p i t w a l l w i t h a minimum number of w e l l s . However, because such deep holes may be beyond the c a p a c i t y of the 40-R d r i l l o p t i o n 3 may not be o p e r a t i o n a l l y f e a s i b l e . In t h a t case, op t i o n 1 would be the next best p r a c t i c a l a l t e r n a t i v e . I t i s recommended that the WIP/GraD system be evaluated by the mine engineering department t o e s t a b l i s h whether i t w i l l s a t i s f y a l l o p e r a t i o n a l and economic requirements. I f the system passes the f e a s i b i l i t y e v a l u a t i o n a t r i a l dewatering program should be i n i t i a t e d t o determine whether the expected l e v e l of performance can be a t t a i n e d i n p r a c t i c e . 88 VERT ICAL DRAIN 4 0 m L0N9 ( F ILLED WITH SANO IF POSSIBLE TO- Re MOVE . CASING AFTER PUMP WITHDRAWAL*! FRACTURED B Y EXPLOSIVES HORIZONTAL. DRAIN INCLINED 2* 4 0 * L O N B INNER 2 / J S L O T T E D COLLECTION S Y S T E M MUST K A C C E S S I B L E SUMF S L O T T E D C A S I N I DOWN HOLE PUMP FIGURE 6-13 WIP/GroD SYSTEM OF PIT DEWATERING 89 6.8 CONSIDERATIONS FOR WALL STABILITY Groundwater d e s t a b i l i z e s open p i t w a l l s through s e v e r a l mechanisms. By f a r the most important i s the re d u c t i o n i n shear s t r e n g t h t h a t i s a s s o c i a t e d w i t h i n c r e a s i n g pore pressure. Shear str e n g t h on a d i s c o n t i n u i t y i s governed by the equation: S = shear s t r e n g t h c = cohesion S = c + (o* -u)*tan (? u = pore pressure 0 = f r i c t i o n angle C = t o t a l normal s t r e s s In analogy, i t becomes more d i f f i c u l t t o s l i d e a book on a t a b l e when i t i s f i r m l y pressed down then when no weight i s placed on i t . Pore pressure a c t s as the l i f t i n g or buoyancy f o r c e , reducing the normal e f f e c t i v e s t r e s s . Water i n a t e n s i o n crack on the u p h i l l s i d e of a loose planar block or wedge can a l s o induce a l a r g e d e s t a b i l i z i n g f o r c e out of the h i l l s i d e . The force i s equal i n magnitude t o the average h y d r o s t a t i c pressure i n the crack times the submerged surface area of the d i s c o n t i n u i t y . Figure 6.14 i s a s c a l e drawing of Equity's east w a l l t h a t i l l u s t r a t e s the p o s i t i o n of the water t a b l e as observed i n three piezometers l o c a t e d on the s e c t i o n . The magnitudes and d i r e c t i o n s of the d e s t a b i l i z i n g pressures t h a t act on the p o t e n t i a l f a i l u r e block are a l s o i n d i c a t e d . Seepage f o r c e a l s o induces a d e s t a b i l i z i n g f o r c e i n the d i r e c t i o n of f l o w . The magnitude of t h i s f o r c e i s : F = seepage f o r c e i = h y d r a u l i c gradient F= i*L*A where: L = length of flow path A = cross s e c t i o n a l area of f a i l u r e wedge 90 l » ( 0 IV40 1V1O mo I MO 1MB ll*0 l l»0 1110 FAILURE BLOCK SHADED FALURE PLANE-PORE D I S T R I B U T I O N FIGURE 6-14 H Y P O T H E T I C A L P L A N E FAILURE I L LUSTRATES INFLUENCE OF GROUNDWATER ON SLOPE STABILITY Figure 6.4, the flownet of the east w a l l , suggests that the g r a d i e n t s are not e x c e s s i v e except at the very bottom of the w a l l so seepage f o r c e s are l i k e l y l e s s important than the shear s t r e n g t h r e d u c t i o n d i scussed above. F i n a l l y , the presence of groundwater can d e s t a b i l i z e smaller b l o c k s on s u r f a c e by fr e e z e - thaw wedging a c t i o n or washing out of gouge or cement out of j o i n t s , e f f e c t i v e l y loosening the bl o c k s and e v e n t u a l l y t r i g g e r i n g a f a i l u r e . Reduction of the pore pressures by some form of drainage i s the only way of reducing the d e s t a b i l i z i n g e f f e c t of groundwater. The most s u c c e s s f u l drainage technique today i s the use of h o r i z o n t a l d r a i n s . Other forms of dewatering such as the deep w e l l dewatering scheme or drainage a d i t s w i l l a l s o improve s t a b i l i t y because the pore pressures i n the p i t w a l l s w i l l be reduced as the water t a b l e i s lowered. 91 Any s u r f i c i a l water should be d i r e c t e d away from the w a l l s because i t i s p r i m a r l y t h i s source of water t h a t q u i c k l y f i l l s t e n s i o n cracks and t r i g g e r s f a i l u r e s . The most severe groundwater induced d e s t a b i l i z i n g f o r c e s are expected i n the east and south w a l l s of the Main Zone p i t because most of the water that flows i n t o the p i t i s b e l i e v e d t o o r i g i n a t e i n the h i l l s east of the p i t . These two w a l l s w i l l be c o n t i n u o u s l y recharged from the h i l l s i d e so the water t a b l e and pore pressures w i l l remain high. In the west w a l l a l l water should e v e n t u a l l y d r a i n out of the w a l l as no major recharge system can be i d e n t i f i e d at s u r f a c e . Therefore, any s p e c i f i c f a i l u r e mode w i l l be l e s s l i k e l y t o f a i l i n the west w a l l then the e a s t . This a d d i t i o n a l s t a b i l i z i n g f a c t o r must be considered i n the design of the west w a l l . To i l l u s t r a t e the importance of a dewatering program at Equity s t a b i l i t y analyses were c a r r i e d out on the most l i k e l y f a i l u r e modes i n design s e c t o r s S4, S5, S6, S9, and S10. Each of these design s e c t o r s i s l o c a t e d on the east s i d e of the Main zone p i t where the g r e a t e s t s t a b i l i t y problems are a n t i c i p a t e d . O r i e n t a t i o n s of f a i l u r e modes f o r the analyses were obtained from S e c t i o n 5 of t h i s r e p o r t . Shear s t r e n g t h estimates of 0=31" , c=10.5 kPa were used. D e t a i l s of how these values were s e l e c t e d are.provided i n S e c t i o n 7. Groundwater c o n d i t i o n s were v a r i e d from dry slope (pore water pressure u=0) t o the t h e o r e t i c a l maximum, u=33 kPa (0.5'^-H/6 equal t o 33 kPa f o r 20 m high wedge). The r e s u l t s of the analyses are i l l u s t r a t e d i n Figure 6.15. 92 FIGURE 6-15 AVERAGE PORE WATER PRESSURE (kPa) I t i s evident that the f a c t o r of s a f e t y decreases as water pressure i n c r e a s e s . Wedges S9-1 and S4-7 remain s t a b l e even at f u l l water pressure because they plunge at shallow angles (30*-35*). On the other hand, wedge S4-3 has a very steep plunge (50°) and remains unstable even under dry c o n d i t i o n s . Because the l i n e of i n t e r s e c t i o n plunges at 50° the wedge w i l l not d a y l i g h t as a m u l t i p l e berm f a i l u r e u nless the o v e r a l l p i t w a l l i s cut steeper than 50°. 93 Wedges w i t h i n t e r s e c t i o n s plunging between 35*and 60° out of the slope are of great e s t concern i n a s t a b i l i t y e v a l u a t i o n because only these wedges can r e s u l t i n l a r g e multi-berm f a i l u r e s ( i . e . they w i l l d a y l i g h t on the p i t w a l l and may be s u f f i c i e n t l y steep t o be u n s t a b l e ) . These wedges are a l s o the most s e n s i t i v e t o changes i n water pressure because they are g e n e r a l l y c l o s e t o l i m i t i n g e q u i l i b r i u m when dry. As water pressure r i s e s the f a c t o r of s a f e t y q u i c k l y drops below u n i t y and f a i l u r e occurs. The t h e o r e t i c a l f a c t o r of s a f e t y of wedges S4-9 and S5-6 drops very q u i c k l y t o zero because they are both t i g h t wedges and the plunge d i r e c t i o n i s oblique t o the berm face. As a r e s u l t pore water pressures q u i c k l y exceed g r a v i t a t i o n a l f o r c e s and a buoyant c o n d i t i o n i s reached. In r e a l i t y , s l i g h t movement of the wedge would a l l o w the excess pore water pressures t o d i s s i p a t e and the f a c t o r of s a f e t y would again i n c r e a s e t o some value near u n i t y . In summary, re d u c t i o n of water pressures w i l l reduce the p r o b a b i l i t y of major f a i l u r e s i n the Main zone p i t by minimizing the d e s t a b i l i z i n g f o r c e s a c t i n g on the wedge. Steep, s i n g l e berm f a i l u r e s that are common on the east u l t i m a t e p i t w a l l w i l l not b e n e f i t from drainage because they are very near l i m i t i n g e q u i l i b r i u m under dry slope c o n d i t i o n s , or p o s s i b l y unstable as soon as they are undercut. 94 6.9 RECOMMENDATIONS FOR FURTHER WORK The p r e l i m i n a r y i n v e s t i g a t i o n i n t o groundwater hydrology c o n d i t i o n s at Equity has i n d i c a t e d that i t should be p o s s i b l e t o dewater the Main Zone p i t w i t h a w e l l engineered dewatering system. The i n v e s t i g a t i o n should now proceed t o the next l e v e l , a two hole t r i a l dewatering program. Pump t e s t s should be attempted at the w e l l s t o confirm that the l o c a l i z e d h y d r a u l i c c o n d u c t i v i t y measurements and assumptions regarding the a i r t r a c i n f l u e n c e on K are v a l i d on a l a r g e s c a l e . The g r a v i t y w e l l drainage method should be evaluated by the mining engineering department. I f proven o p e r a t i o n a l l y and economically f e a s i b l e , the system should be promptly t e s t e d as i t appears t o have co n s i d e r a b l e p o t e n t i a l f o r improving p i t w a l l s t a b i l i t y and reducing the need f o r s l u r r y e x p l o s i v e s . The dewatering t r i a l s c o u l d be incorpo r a t e d i n t o the f i r s t stage of the a c t u a l dewatering program. A d d i t i o n a l work i s a l s o r e q u i r e d i n c o n t i n u i n g the piezometer monitoring p o r t i o n of the p r e l i m i n a r y program and i n the completing of s e v e r a l s m a l l jobs that d i d not get f i n i s h e d during the summer. 6.9.1 Completion of P r e l i m i n a r y Study A t o t a l of fourteen piezometer s i t e s now e x i s t i n the Main Zone. Piezometers P09 and P13 were not completed during the summer. I f p o s s i b l e , the standpipes should be i n s t a l l e d before the l o c a t i o n s are bu r i e d by snow. The s t e e l drum p r o t e c t i v e covers should now be completed. They belong over the standpipes t o p r o t e c t them from damage and make them e a s i e r t o f i n d f o r u n f a m i l i a r monitors. M o n i t o r i n g of the piezometers should be continued t o b e t t e r d e f i n e the peak seasonal pore pres s u r e s , because these w i l l have the great e s t impact on 95 slope s t a b i l i t y . M onitoring w i l l be r e q u i r e d on a weekly b a s i s from mid A p r i l t o June t o a t t a i n t h i s g o a l . I t i s a l s o d e s i r a b l e t o f u r t h e r d e f i n e the seasonal f l u c t u a t i o n s of the water t a b l e i n order t o t o a c c u r a t e l y e s t a b l i s h whether f u t u r e observed changes i n water l e v e l s are due t o dewatering or seasonal f l u c t u a t i o n s . I d e a l l y , monitoring of e x i s t i n g piezometers should continue on a monthly b a s i s , but because many of the s i t e s w i l l not be e a s i l y a c c e s s i b l e or even l o c a t a b l e during the w i n t e r , i t i s recommended th a t only one e a s i l y a c c e s s i b l e piezometer l o c a t i o n be monitored during the w i n t e r . This program w i l l p r ovide s u f f i c i e n t i n f o r m a t i o n on seasonal f l u c t u a t i o n s as these changes i n p i e z o m e t r i c l e v e l s appear t o be f a i r l y c o n s i s t e n t at the two l o c a t i o n s monitored e x t e n s i v e l y during the summer, and i t i s hoped t h a t a s i m i l a r response can be expected over the e n t i r e Main zone area. 6.9.2 I n i t i a l Dewatering / Pump Tests Two 30 t o 40 m deep pumping w e l l s should be i n s t a l l e d i n the bottom of the i n t e r i o r p i t as the f i r s t stage of the dewatering program. One of the w e l l s should be completed i n the v o l c a n i c s along the south w a l l , the other should be attempted along the east w a l l i n the area of the suspected Bessemer Creek f a u l t . The d r i l l holes should be l i n e d w i t h p e r f o r a t e d c a s i n g ( v e r t i c a l s l o t s cut i n t o pipe w i t h t o r c h ) . Pumping t e s t s should be c a r r i e d out during the i n i t i a l o peration of these w e l l s t o e s t a b l i s h the h y d r o l o g i c parameters and t o monitor the s i z e and shape of the drawdown cones. Monitoring w e l l s should be i n s t a l l e d at 5, 10, 20 & 50 m along two l i n e s r a d i a t i n g from the w e l l s i n t o the p i t . The response i n these w e l l s w i l l i n d i c a t e whether the zone being dewatered i s behaving as an inhomogeneous rockmass w i t h 96 impermeable zones of f a u l t gouge, or whether b l a s t i n g has f r a c t u r e d these zones s u f f i c i e n t l y t o create a r e l a t i v e l y homogeneous medium of high t r a n s m i s s i v i t y . I f i t i s discovered that gouge zones are l i m i t i n g the r a d i u s of i n f l u e n c e of the pumping w e l l s , then f u r t h e r f i e l d work w i l l be r e q u i r e d t o i d e n t i f y any such s t r u c t u r e s before a d d i t i o n a l w e l l s are i n s t a l l e d and then l o c a t e the w e l l s i n the c e n t r a l p o r t i o n s of the gouge bounded b l o c k s . 6.9.3 G r a v i t y W e l l Drainage The g r a v i t y w e l l method of drainage should be c a r e f u l l y evaluated i n terms of cost and p r a c t i c a l o p e r a t i o n i n the Main Zone mining environment. This method has many advantages over the other drainage methods d i s c u s s e d , e s p e c i a l l y o p erating c o s t s , improved slope s t a b i l i t y , and p o s s i b l y , increased use of ANFO. The method may a l s o be s u c c e s s f u l i n dewatering the gabbro u n i t because a c l o s e spacing of w e l l s i s p r a c t i c a l w i t h t h i s method whereas i t would be p r o h i b i t e v l y expensive i f pumps would have t o be purchased and maintained. Dewatering i s recommended i n t h a t area because high groundwater pressures are known to e x i s t . The pressures w i l l exert a d e s t a b i l i z i n g f o r c e on a l l unfavourably o r i e n t e d d i s c o n t i n u i t i e s . R e c a l l that approximately f i v e percent of major d i s c o n t i n u i t i e s i n the east w a l l d i p shallower than the o v e r a l l slope and could r e s u l t i n a m u l t i p l e berm f a i l u r e . The t e s t should c o n s i s t of four v e r t i c a l 9" holes d r i l l e d t o 30 m depth. A c a s i n g i s not r e q u i r e d unless the hole cannot be maintained open t o f u l l depth. The w e l l should be f i l l e d w i t h coarse sand. Sand plac e d near the bottom of the hole should be b r i g h t l y p a i n t e d . A 10 m spacing should be maintained between h o l e s . H o r i z o n t a l d r a i n h o l e s 97 i n c l i n e d s l i g h t l y upward should be d r i l l e d t o i n t e r c e p t the v e r t i c a l w e l l s from a berm 30 m below the w e l l c o l l a r s . The d r a i n should be cased. The ca s i n g should be f u l l y p e r f o r a t e d f o r one t h i r d of i t s l e n g t h , the second t h i r d should be p e r f o r a t e d only on the top s u r f a c e , the f i n a l t h i r d c l o s e s t t o the w a l l should not be p e r f o r a t e d at a l l . The reasoning i s t o capture as much water as p o s s i b l e and then prevent i t from d i s c h a r g i n g back i n t o the rock face above the water t a b l e . I f the d r a i n does not i n t e r c e p t the d r i l l hole (no coloured c u t t i n g s are observed) then a l i g h t charge should be detonated as c l o s e as p o s s i b l e t o the v e r t i c a l w e l l t o open up more flowpaths and improve drainage. The i n i t i a l t e s t should be l o c a t e d i n the v o l c a n i c u n i t s , near the southeast corner of the i n t e r i o r p i t i f access can be a t t a i n e d t o benches of i d e a l geometry. I f t h i s i s not p o s s i b l e an a l t e r n a t e s i t e w i l l have t o be s e l e c t e d . 98 7.0 SHEAR STRENGTH CONSIDERATIONS A n a l y s i s of the- s t r u c t u r a l data has i d e n t i f i e d the most l i k e l y f a i l u r e modes i n each design s e c t o r . Whether a wedge or plane block t h a t d a y l i g h t s out of the p i t w a l l w i l l a c t u a l l y f a i l w i l l depend on the shear s t r e n g t h parameters and s t r e s s c o n d i t i o n s a c t i n g on the f a i l u r e s u r f a c e s . Groundwater pressures are a l s o very important. I t i s b e n e f i c i a l t o have a rough idea of how c l o s e are p o t e n t i a l wedges w i t h i n each design sector t o f a i l u r e , i . e . what i s t h e i r f a c t o r of s a f e t y . I f the f a c t o r of s a f e t y i s below u n i t y then the r i s k o f undercutting the s t r u c t u r e s should be c a r e f u l l y evaluated. I f any wedges or blocks begin t o move i n the p i t , s t a b i l i z a t i o n may be r e q u i r e d t o ensure safe working c o n d i t i o n s below, e s p e c i a l l y i f the f a i l u r e i s above a haul road or other key s e r v i c e s i n the p i t . Shear strengths on the f a i l u r e s u r f a c e w i l l have t o be known t o i d e n t i f y the method of s t a b i l i z a t i o n , e.g. w i l l drainage be s u f f i c i e n t , or what magnitude of support w i l l be needed t o s t a b i l i z e the wedge. An i n v e s t i g a t i o n i n t o shear s t r e n g t h was c a r r i e d out during the summer of 1984 as p a r t of the Slope Design Program. The i n v e s t i g a t i o n had three phases: 1) p o i n t load t e s t i n g t o determine u n i a x i a l compressive s t r e n g t h , 2) measurements of plunge angle of berm f a i l u r e s and s l i p t e s t s t o estimate f r i c t i o n angle jf, and 3) back a n a l y s i s of berm s c a l e wedge f a i l u r e s t o compute fif and cohesion from a c t u a l s l i d e s . This s e c t i o n summarizes the r e s u l t s of the shear s t r e n g t h i n v e s t i g a t i o n s . Recommended values of cohesion and f r i c t i o n angle are presented f o r c o n d i t i o n s of low c o n f i n i n g s t r e s s (e.g. berm s c a l e 99 failures). Additional work should be undertaken to define the failure criterion at" higher stress levels that would arise during a major pit wall failure. 7.1 POINT LOAD TESTING Point load tests were performed on a total of 112 core samples from the 1984 exploration d r i l l i n g program. Each test was carefully observed and pertinent data recorded. This included rock type, sample location, point load index I , failure mode, and any additional observations such as presence of weathering or alteration. A computer program was developed to s t a t i s t i c a l l y determine a representative uniaxial shear strength for each rock type. A report t i t l e d "Point Load Testing Program and Results" dated 84/06/19 discusses a l l aspects of the point load testing program and methods of analysis. Results of the testing program indicate that the major rock units in the Main Zone have reasonably high intact rock strengths. Therefore, failure w i l l be controlled by unfavourably oriented discontinuities. The gabbro proved to be the strongest unit, l a p i l l i tuff was generally rated strong, ash tuff of moderate strength, and dust tuff proved moderately weak. Quantitative results are summarized in Table 7.1. Table 7.1 Rock Type Load to Failure (kN) Design Strength (MPa) Description Rating dust tuff 79 44.3 moderately weak R2 ash tuff • 156 87.6 moderately strong R3 l a p i l l i tuff 200 112.3 strong R4 gabbro 455 255.4 very strong R5 andesite dyke 313 175.7 strong R4 quartz l a t i t e 359 201.5 strong R4 dike 100 7.2 ESTIMATION OF FRICTION ANGLE Angles of plunge' were measured on 17 s i n g l e bench plane and near planar wedge f a i l u r e s i n the Main Zone p i t to get an approximate idea of the minimum angle of f r i c t i o n . The observations are p l o t t e d i n Figure 7.1. No f a i l u r e s were observed u n t i l plunge angles exceeded 32°. I t can be concluded that a f a i l u r e i s u n l i k e l y i f the plunge of a wedge i n t e r s e c t i o n or f a i l u r e plane i s shallower than 30°. Very crude s l i p t e s t s were c a r r i e d out by p l a c i n g rocks on the p i t wall and measuring the plunge angle at the onset of s l i p . S l i p t e s t angles varied between 32°and 44°. Fresh, gouge f r e e , reasonably smooth surfaces were used for the t e s t s . The measured angles are i n d i c a t i v e of the e f f e c t i v e f r i c t i o n angle 0' ((2f + roughness angle i ) . €2 z o 60 58 « OC 56 Ul 54 z 52 £ O 50 Ui o 48 3 46 ac 44 OT 0. 42 Zi tn 40 * 38 Ui 36 (3 Z 34 Z) 32 _l 0. 30 28 ° o o o ° o slip t e s t p l u n g e o f f a i l u r e o o • p ° o o O 10 12 14 16 T E S T NUMBER 18 20 Figure 7.1 DETERMINATION OF APPROXIMATE BASIC FRICTION ANGLE 1 0 1 A f i r s t order estimate of ff can be made by analyzing the above failures and tests as simple plane failures and making several assumptions to reduce the number of unknowns. In the most general case the factor of safety for a plane failure can be expressed as: Eq. 7.1 F = resisting forces destabilizing forces F = factor of Safety -e- = c = cohesion 0 = A = area of failure plane V = W = weight of sliding block U = S = - cA+(Wcos(-e^-u-vsin(^ )tan(fl) Ws in (©•) -Vcos ( + S angle of plunge of failure surface fr i c t i o n angle force due to water in tension crack up l i f t force due to pore pressure seismic force The water table in the upper portion of the Main Zone pi t where the observations were made is 10-20 m below surface so the berms are dry. Therefore, U and V can be dropped from Equation 7.1. If the failures occur well after detonation S w i l l also be equal to zero. This assumption is made because i t is conservative, generating low values of 0 i f a seismic force was present. Assuming U, V and S are zero, equation 7.1 can be simplified to: Eq. 7.2 t a n . = F tan (-©•)• At the onset of failure the destabilizing forces are exactly equal to the driving forces and F is equal to unity (condition of limiting equilibrium). At this moment 0* is equal to the plunge angle -e-. Many of the steeper wedges were probably stable only because they were keyed in at the toe. As soon as this support was removed they slipped down. For these failures F is less than unity but the exact magnitude is indeterminate so the only conclusion that can be made i s that 0 is smaller than in magnitude. Therefore, Equation 7.2 was applied only to the minimum observed plunge angle in estimating 102 It should be noted that the only wedge failure that occurred during the summer f e l l out some time after the face was mucked out. The slide was triggered by vibrations from a shovel working nearby. The wedge must have therefore been very close to limiting equilibrium. The plunge angle was 44* . In this instance Equation 7.2 can be applied with confidence with F=l so the f r i c t i o n angle for that surface must be near 44° . The relatively high f r i c t i o n angle is probably due to the roughness that was observed on the failure planes. It is also possible that some cohesion was present. In summary, the f r i c t i o n angles in the Main Zone p i t are li k e l y in the range 30-45°, and vary with the roughness characteristics of the failure plane. 7.3 BACK ANALYSIS OF BERM FAILURES The factor of safety can be computed for a wedge in much the same manner as for the plane failure discussed in the previous section, although the formulation is more complex because of geometric constraints. In principle, the factor of safety is a ratio of resisting forces developed on the two failure surfaces to the driving forces of gravity and pore pressure acting on the wedge. The F.O.S. can be calculated i f wedge dimensions, groundwater pore pressure, shear strength parameters c and 0, and rockmass density are known. Wedge dimensions and rockmass density are easily measured. If no seepage is observed on the berm i t is likely that water pressure close to the p i t face is zero. If water is seeping out of the berm then a higher value of u must be specified in the analysis (see Appendix B.2 for guidelines to groundwater pressure assumptions). Thus, the only 103 parameters s t i l l r e q u i r e d t o c a l c u l a t e the f a c t o r of s a f e t y are c and Jjf. I t i s d i f f i c u l t t o e s t a b l i s h accurate shear s t r e n g t h parameters t o input i n t o the s t a b i l i t y a n a l y s i s . Several methods of determining them are a v a i l a b l e , i n c l u d i n g : e m p i r i c a l c o r r e l a t i o n s , l a b o r a t o r y t e s t s , i n - s i t u t e s t s , and back analyses of a c t u a l f a i l u r e s . The recommended approach i s t o use a l l four methods t o ob t a i n s e v e r a l estimates of c and 0, and then use engineering judgement t o s e l e c t the most reasonable values. In the back a n a l y s i s approach the assumption i s made tha t the wedge a t t a i n e d l i m i t i n g e q u i l i b r i u m j u s t before f a i l u r e so F.O.S.=1.0. The f a c t o r of s a f e t y equation can, then be so l v e d f o r c and 0. Because only one equation i s a v a i l a b l e f o r two unknowns a unique s o l u t i o n i s not p o s s i b l e , but a range of c/<j> p a i r s can be determined. A computer program was developed as p a r t of the slop e design p r o j e c t t o c a l c u l a t e wedge s t a b i l i t y and c a r r y out a back a n a l y s i s t o determine a range of c/$ p a i r s that s a t i s f y the c o n d i t i o n of l i m i t i n g e q u i l i b r i u m . The program SWEDGE i s based on the "short s o l u t i o n f o r r a p i d computation of wedge s t a b i l i t y " (Hoek, 1981). The program i s f u l l y documented i n Appendix B. Eight l a r g e r berm f a i l u r e s were s e l e c t e d f o r the back analyses. Wedge dimensions and o r i e n t a t i o n s v a r i e d . F i e l d data f o r the analyses i s ta b u l a t e d i n Appendix C.1. Appendix C.2 l i s t s the output from SWEDGE f o r each back a n a l y s i s . F i g u r e s 7.2 and 7.3 summarize the r e s u l t s of the back analyses. Each graph i s a p l o t of cohesion vs. f r i c t i o n angle t h a t s a t i s f y l i m i t i n g e q u i l i b r i u m f o r the ei g h t wedges. In developing Figure 7.2 water pressure was assumed t o be zero, i . e . the slope was assumed dry. 104 In Figure 7.3 the average groundwater c o n d i t i o n was assumed t o be 0.5(iM-H/6) or one h a i f of the t h e o r e t i c a l maximum value. Because a l l s l i p planes examined i n t h i s study were dry (DISCODAT code 3 or lower) Figure 7.2 i s used f o r subsequent analyses as i t most l i k e l y represents the c o n d i t i o n s at f a i l u r e . FRICTION ANGLE 4 Friction Anglo and Citation Roquirod tor Limit I nf Equilibrium (F.O.S.-I) Undtr Dry Slop* Gioundweror Condition. FRICTION ANGLE 0 Friction Anglo ond Cohttmn Rtqutrod for Limiting Equilibrium ( F O S • II Undir Maximum Eiptctod Groundwattr Candlflont 105 A co n s e r v a t i v e i n t e r p r e t a t i o n of Figure 7.2 would be t o assume zero cohesion and t o take the minimum f r i c t i o n angle r e q u i r e d t o maintain s t a b i l i t y of the most s t a b l e wedge, e.g. 30°for wedge 2, as r e p r e s e n t a t i v e . A l l other wedges r e q u i r e greater shear s t r e n g t h , so they are assumed t o be unstable and t o have s l i p p e d as soon as the toe was exposed. This approach r e s u l t s i n shear s t r e n g t h parameters of c=0, 0=30°. The co n s e r v a t i v e approach should not be used i n open p i t mine design because some f a i l u r e s can be t o l e r a t e d ; even d e s i r e d t o i n d i c a t e t h a t the p i t i s not overdesigned. A p r o b a b i l i t y f u n c t i o n approach has been developed t o obt a i n more r e a l i s t i c values of shear s t r e n g t h parameters based on the back a n a l y s i s data. In t h i s approach the r e l a t i v e p r o b a b i l i t y of s a t i s f y i n g l i m i t i n g e q u i l i b r i u m of a l l wedges i s determined f o r each c/0f data p o i n t . The p r o b a b i l i t y f u n c t i o n can be generated by manually contouring a d i s c r i t i z e d v e r s i o n of Figure 7.2 using a counting c i r c l e . More elegant and time saving methods of doing t h i s task can be developed. Figure 7.4 i s a contoured p l o t of the p r o b a b i l i t y f u n c t i o n f o r the e i g h t wedges s t u d i e d . There i s a w e l l d e f i n e d maximum at 0=31° , c=10.5 kPa. These shear s t r e n g t h parameters r e s u l t i n c o n d i t i o n s nearing l i m i t i n g e q u i l i b r i u m i n the l a r g e s t number of wedges t e s t e d and are the best estimate f o r c and 0 based on e x i s t i n g back a n a l y s i s data. 106 20 29 30 39 40 43 30 FRICTION ANGLE <t 7.4 SHEAR STRENGTH SUMMARY Shear s t r e n g t h i s a very important parameter i n p i t design. A s t r u c t u r a l study (as d e s c r i b e d i n s e c t i o n s 5 and 9) can d e f i n e the most probable f a i l u r e modes i n each design s e c t o r . The design c r i t e r i o n f o r numerous p i t s has been t o minimize the number of f a i l u r e modes th a t d a y l i g h t . Such an approach i s c e r t a i n l y more e f f e c t i v e then designing t o an o v e r a l l slope angle of 45° re g a r d l e s s of g e o l o g i c s t r u c t u r e ; however, i f s t a b i l i t y analyses i n d i c a t e t h a t the p o t e n t i a l f a i l u r e modes are s t a b l e i f allowed t o d c i y l i g h t (F.0.S.>1.2) then the p i t w a l l angle can be s a f e l y steepened even f u r t h e r . Shear s t r e n g t h parameters have been estimated f o r the Main Zone p i t from s l i p t e s t s , minimum angle of f a i l u r e plunge, and back analyses. 107 A l l of these analyses i n d i c a t e that the parameters can vary c o n s i d e r a b l y i f l i m i t i n g e q u i l i b r i u m i s assumed. By using the p r o b a b i l i t y f u n c t i o n a narrower range of values f o r c and $ have been i d e n t i f i e d . The mean r e s u l t s of t h i s approach are c=10.5 kPa, 0=31°. They are c o n s i s t e n t w i t h r e s u l t s from s l i p t e s t s and plunge measurements (0=30° t o 35°), and w i t h r e s u l t s c i t e d i n p u b l i s h e d l i t e r a t u r e f o r s i m i l a r c o n d i t i o n s . The r e s u l t s summarized above have been generated from a l i m i t e d data base. In a d d i t i o n , the methods used r e q u i r e d s e v e r a l assumptions th a t may not n e c e s s a r i l y be v a l i d . Further data c o l l e c t i o n , t e s t i n g , and engineering a n a l y s i s must be c a r r i e d out before the shear s t r e n g t h / s t a b i l i t y e v a l u a t i o n approach can be used f o r f i n a l design of Equity's p i t s l o p e s . P r e l i m i n a r y r e s u l t s using t h i s approach are presented i n s e c t i o n 9 and achieve favourable r e s u l t s but the "minimimum f a i l u r e modes d a y l i g h t i n g " concept i s s t i l l used as the f i n a l design c r i t e r i o n i n t h i s r e p o r t . The f o l l o w i n g program i s recommended t o b e t t e r d e f i n e the shear s t r e n g t h parameters i n the Main Zone p i t : 1. S l i p Tests (30) 2. Plunge Angle Measurements (30) 3. Back Analyses as s l i d e s occur 4. D i r e c t Shear Tests on Major D i s c o n t i n u i t i e s (10) 5. Comparison of R e s u l t s t o Emprical F a i l u r e C r i t e r i a Note t h a t the bracketed numbers are rough g u i d e l i n e s t o the q u a n t i t i e s of t e s t s r e q u i r e d . T e s t i n g should continue u n t i l the s t a b i l i t y engineer i s confident that f u r t h e r t e s t i n g would not a l t e r h i s best estimate. I f r e s u l t s are c o n s i s t e n t i n a l l above t e s t s then i t i s l i k e l y t h a t fewer t e s t s w i l l be r e q u i r e d than the suggested q u a n t i t i e s l i s t e d above. Test methods 1 and 2 w i l l l i k e l y y i e l d s i m i l a r r e s u l t s as previous t e s t s , but are so easy t o c a r r y out that 108 the data base can be increased without too much e f f o r t . The c/0 p r o b a b i l i t y f u n c t i o n w i l l be much more r e l i a b l e w i t h a l a r g e r data base, e s p e c i a l l y i f the back analyses are c a r r i e d out on f a i l u r e s t h a t occured w e l l a f t e r the slope was mucked out, i n d i c a t i n g c o n d i t i o n s near l i m i t i n g e q u i l i b r i u m . The d i r e c t shear t e s t s w i l l provide f r i c t i o n angles and cohesion values that can be used t o v e r i f y the r e s u l t s of the back analyses and provide sound evidence t h a t the assumptions made i n the analyses are v a l i d . 109 8.0 BLASTING CONSIDERATIONS 8.1 INFLUENCE OF ELASTING ON WALL STABILITY Detonation of e x p l o s i v e s c l o s e t o the p i t w a l l can cause s t r u c t u r a l damage to the rock behind the f i n a l d i g l i n e , reducing o v e r a l l w a l l s t a b i l i t y by developing f r a c t u r e cracks i n the slope and by i n c r e a s i n g the frequency of r a v e l l i n g and s m a l l berm f a i l u r e s i n the p i t . By c a r e f u l l y o p t i m i z i n g the t r i m b l a s t i n g design s e v e r a l o p e r a t i o n a l advantages can be r e a l i z e d . Foremost, when the rock forming the f i n a l w a l l i s i n t a c t i t w i l l stand at a steeper bermface angle. Where s t a b i l i t y of the benches c o n t r o l s o v e r a l l p i t angle there i s good p o t e n t i a l f o r steepening the p i t w a l l i f the bermface can be excavated t o 70° from the current 65*. Less frequent r a v e l l i n g and berm f a i l u r e s w i l l reduce the chance of broken power c a b l e s , drainage pipes ( e s p e c i a l l y when the drainage system i s i n s t a l l e d ) , and rock on the haul roads. Berms v a i l r e q u i r e l e s s c l e a r i n g and w i l l be more e f f e c t i v e i n c a t c h i n g any r a v e l l i n g rock t h a t does f a l l . Greater s a f e t y w i l l be r e a l i z e d . 8.2 PARAMETERS THAT CONTROL BLAST PERFORMANCE Breakage of i n t a c t rock i s caused by two mechanisms during a b l a s t . The detonation of an e x p l o s i v e generates a l a r g e q u a n t i t y of gases that are i n i t i a l l y c o nfined i n the rockmass under e x t r e m e l l y high pressure. The e x p l o s i o n t r a n s f e r s vast amounts of energy t o the rockmass as i f a b i g hammer h i t the rock. Seismic waves (Primary, Secondary and Raleigh) t r a n s p o r t the energy r a d i a l l y from the b l a s t . When the wavefront passes through a p o i n t i n the rockmass a f o r c e i s exerted 110 on the rock p a r t i c l e s at that p o i n t and they are d i s p l a c e d . The l e v e l of s t r a i n and peak p a r t i c l e v e l o c i t i e s are d i r e c t l y dependent on the type and st r e n g t h of the wavefront. F r a c t u r e of the rockmass occurs when the maximum e l a s t i c s t r a i n of the rockmass i s exceeded; onset o f f r a c t u r i n g by t e n s i l e waves g e n e r a l l y begins when peak p a r t i c l e v e l o c i t i e s exceed 250 cm/s. The f i r s t g oal of the t r i m b l a s t design i s t o reduce the amount of energy per delay so peak p a r t i c l e v e l o c i t i e s exceeding 250 cm/s are a t t a i n e d only w i t h i n a small d i s t a n c e beyond the row of l i n e h o l e s . Figure 8.1 1. Detonation - high pressure gas created. 2. P wave has adequate energy t o f r a c t u r e rock i n compression f o r 4 diam. 3. P wave r e f l e c t e d from f r e e f a c e , forms t e n s i l e wave p a r a l l e l t o face. 4. T e n s i l e wave forms cracks s i n c e t e n s i l e s t r e n g t h of rock low. 5. Gases expand i n t o t e n s i l e c r a c k s , heave muck ( i l l u s t r a t e d on previous row. 6. New f r e e face c r e a t e d ( i l l u s t r a t e d on previous b u f f e r row). Expansion of the e x p l o s i v e gases does most of the a c t u a l displacement of the rockmass. Gases penetrate i n t o e x i s t i n g weaknesses and cra c k s opened up by the passing wavefronts. D i f f e r e n t i a l gas 111 pressures exert a very s u b s t a n t i a l f o r c e on i n d i v i d u a l blocks of rock, pushing them apart and outward toward the f r e e face. I f i n s u f f i c i e n t l y c o n f i n e d , escaping gases can t r i g g e r c r a t e r i n g and f l y r o c k . The second goal of t r i m b l a s t design i s t o minimize the q u a n t i t y of gases t h a t penetrate the rockmass beyond the f i n a l d i g l i n e . The mechanics of a b l a s t are i l l u s t r a t e d i n Figure 8.1. The f o l l o w i n g parameters can be s y s t e m a t i c a l l y v a r i e d i n the o p t i m i z a t i o n of t r i m b l a s t performance: 1. Powder Factor (mass r a t i o of e x p l o s i v e used/rock broken) Goal: - as low as p o s s i b l e w h i l e maintaining adequate fragmentation. 2. E x p l o s i v e Charge per Hole Goal: - as low as p o s s i b l e w h i l e ensuring adequate q u a n t i t i e s f o r detonation and c o m p a t i b i l i t y w i t h l o a d i n g equipment. 3. Hole Spacing ( e s p e c i a l l y t r i m row) Goal: - d i c t a t e d by powder f a c t o r and charge per hole. 4. Burden ( d i s t a n c e between rows) Goal: - w e l l balanced, p r o v i d i n g adequate confinement without choking. 5. F i r i n g Order Goal: - Depends on c o n t r o l b l a s t i n g technique. Should ensure that every hole detonates adjacent t o a f r e e face. 6. Delays Goal: - Adequate delay t o prevent reinforcement of i n d i v i d u a l wavefronts. 7. Power of Explosive/Detonating Speed Goal: - D i c t a t e d by economics and water c o n d i t i o n s . Low s t r e n g t h e x p l o s i v e should be used i n detonation of l i n e holes i n cushion b l a s t s . 8. C o n t r o l B l a s t i n g Method ( p r e - s p l i t or cushion b l a s t i n g ) Goal: - Method should be d i c t a t e d by rock c o n d i t i o n s . 9. B l a s t Hole Diameter Goal: - Smallest diameter production d r i l l should be used i n d r i l l i n g of l i n e holes t o maximize height of e x p l o s i v e column. 10. S u b - D r i l l Depth Goal: - As shallow as p o s s i b l e w h i l e developing adequate fragmentation on rocks at bottom of b l a s t . 112 To be e f f e c t i v e , the o p t i m i z a t i o n t r i a l s must be w e l l s t r u c t u r e d , docummented, and c a r e f u l l y evaluated. Any m o d i f i c a t i o n s should a l s o be d i s c u s s e d with the b l a s t i n g personnel before they are implemented t o determine whether they would pose any o p e r a t i o n a l problems. S u f f i c i e n t observations of cu r r e n t t r i m b l a s t performance must be made p r i o r t o the t r i a l s so that any changes can be adequately evaluated. 8.3 CURRENT BLASTING PRACTICE At present, a l l t r i m b l a s t s at Equity are cushioned. The t r i m p a t t e r n c o n s i s t s of two b u f f e r rows and a t r i m l i n e . The charge per hole i s reduced i n the t r i m p a t t e r n . To maintain the powder f a c t o r at the production b l a s t l e v e l of 0.22 Kg/tonne the spacings are t i g h t e n e d up from the standard 4x5 and 5x5 m pro d u c t i o n p a t t e r n s t o dimensions i l l u s t r a t e d i n Figure 8.2. Damage i n the f i n a l w a l l i s a f u n c t i o n of the energy contained i n each s e i s m i c wave th a t i s generated during an e x p l o s i o n . A delay i s placed between each hole i n the t r i m p a t t e r n t o prevent reinforcement of s e v e r a l low energy waves i n t o one high energy wave f r o n t . 15 ms and 25 ms delays are used between each l i n e h o l e , 25 ms delays between each b u f f e r h o l e , and 100 ms delays between each O I O O 0 3 . o - * 0 O O line holes in O O O - 4.0 — * Q O O Ist buffer row q O .0 O o O 2' buffer row Figure 8.2 PRESENT TRIM BLAST PATTERN a l l d imensions In m 113 row. The detonation sequence i s as f o l l o w s : 1) second b u f f e r row, 2) f i r s t b u f f e r row, and 3) l i n e h o l e s . The powder f a c t o r i n the l i n e holes i s reduced t o 0.148 kg/tonne t o f u r t h e r reduce the amount of e x p l o s i v e per delay. The l i n e holes are always loaded w i t h higher s t r e n g t h s l u r r y e x p l o s i v e s , the b u f f e r rows are charged w i t h ANFO unless water c o n d i t i o n s are severe, i n which case s l u r r y has t o be used. The standard t r i m b l a s t p a t t e r n o u t l i n e d above i s used i n a l l rock c o n d i t i o n s . 8.4 AREAS OF POTENTIAL IMPROVEMENT Equity S i l v e r Mines has a good c o n t r o l b l a s t i n g program t h a t reduces the damage t o the f i n a l w a l l s u b s t a n t i a l l y from l e v e l s of damage that c o u l d be expected i f production b l a s t s were used throughout. S u b s t a n t i a l work remains t o be done on a d d i t i o n a l refinement of the t r i m b l a s t design t o f u r t h e r improve rock c o n d i t i o n s i n the f i n a l w a l l . Research should focus on: 1) use of lower s t r e n g t h ANFO i n the l i n e holes where p o s s i b l e , 2) f u r t h e r r e d u c t i o n i n weight of e x p l o s i v e per delay, 3) r e d u c t i o n i n l i n e hole burden, 4) v a r i a t i o n i n t r i m b l a s t design t o match rock c o n d i t i o n s ( p a r t i c u l a r l y rock t y p e ) , 5) i n c l u s i o n o f "Hercudet" i n i t i a t i o n system i n t o t r i m b l a s t design, and 6) design of detonation sequence t o maximize formation o f f r e e face. 8.4.1 Use of ANFO i n Line Holes In the optimum cushion b l a s t narrow diameter l i n e holes are d r i l l e d on a t i g h t spacing. The l i n e holes have a reduced burden. Each hole i s delayed. A low st r e n g t h e x p l o s i v e i s used t o " p e e l " the f i n a l rock o f f the w a l l , l e a v i n g the rock behind the f i n a l d i g l i n e w i t h minimal damage. 114 In a mining environment the i d e a l cushion b l a s t cannot be j u s t i f i e d because of equipment and c o s t / r e t u r n c o n s i d e r a t i o n s , but the concept can be a p p l i e d t o reduce b l a s t damage. An eq u i v a l e n t mass charge of a lower s t r e n g t h e x p l o s i v e , e.g. ANFO, w i l l do l e s s damage t o the f i n a l w a l l because the seismic wave w i l l be weaker, a t t e n u a t i n g t o below the 250 cm/sec damage t h r e s h o l d i n a shor t e r d i s t a n c e . The use of ANFO i n l i n e holes has a d d i t i o n a l advantages t h a t : 1) the charge per hole can be p r e c i s e l y c o n t r o l l e d ( i . e . not l i m i t e d t o 30 l b . shots as w i t h s l u r r y ) . As a r e s u l t there w i l l be greater f l e x i b i l i t y i n changing spacing or the powder f a c t o r i n the l i n e h o l e s . 2) Less expensive e x p l o s i v e s w i l l be u t i l i z e d whenever groundwater c o n d i t i o n s permit. 3) Only one type of e x p l o s i v e w i l l be r e q u i r e d i n dry areas so loa d i n g w i l l be s i m p l i f i e d . When wet holes are encountered p l a s t i c l i n e r s i n sonnet tubes or s l u r r y w i l l have t o be u t i l i z e d . Far fewer wet holes should be encountered a f t e r a p i t dewatering system i s i n s t a l l e d . 8.4.2 Reduction of Charge per Hole One of the most r e l i a b l e methods of p r e d i c t i n g b l a s t damage i s the U.S. Bureau of Mines e m p i r i c a l formula that r e l a t e s peak p a r t i c l e v e l o c i t y of the rockmass t o r a d i a l d i s t a n c e from detonation and weight of e x p l o s i v e charge per delay: V = peak p a r t i c l e v e l o c i t y ( i n / s ) fi R = r a d i a l d i s t a n c e from b l a s t ( f t ) Eq. 8.1 V = K*(R/<M) W = weight e x p l o s i v e per delay (lb) K = constant, f u n c t i o n of rockmass B = constant, f u n c t i o n of rockmass 115 The constants K . and B are dependent on the e l a s t i c p r o p e r t i e s of the rockmass. T y p i c a l values are K = 2 6 to 2 6 0 and B = - 1 . 6 . Given that rock begins t o f r a c t u r e at V = 1 0 0 i n / s and l i n e holes are loaded w i t h 6 0 l b of e x p l o s i v e per delay a range of dista n c e s t o which the rock w i l l be f r a c t u r e d can be p r e d i c t e d by s o l v i n g equation 8 . 1 f o r R. Eq. 8 . 2 R = yw*(V/K)^* The r e s u l t s of s e v e r a l c a l c u l a t i o n s are t a b u l a t e d below. Table 8.1 Assumption K P W(lb) R ( f t ) c u r r e n t c o n s e r v a t i v e 26 -1.6 60 3.34 current worst case 300 -1.7 60 14.78 current most l i k e l y 200 -1.6 60 11.95 The U.S. Bureau of Mines formula i n d i c a t e s that at present the damage from detonation of the t r i m b l a s t extends w e l l beyond the f i n a l d i g l i n e , perhaps by as much as 15 f t . (assuming K and B values chosen are r e p r e s e n t a t i v e of the rockmass). The t r i m b l a s t o p t i m i z a t i o n t e s t s should focus on reducing the charge per delay. However, the charge cannot be reduced too much because i t would only f i l l the very bottom of the hole . A reasonable g o a l would be t o a t t a i n a 50 l b charge per l i n e h o l e . This m o d i f i c a t i o n would r e q u i r e a 2.5 m l i n e hole spacing t o maintain the l i n e h o l e powder f a c t o r at the present l e v e l of 0.148 Kg/tonne. A 2.5 m l i n e hole spacing was s u c c e s s f u l l y t e s t e d i n one t r i a l b l a s t i n 1984. G u i d e l i n e s i n the l i t e r a t u r e a l s o suggest that spacing of the l i n e h o l e s should be approximately 1/2 of the production spacing f o r maximum p r a c t i c a l cushion e f f e c t . Figure 8.3 i l l u s t r a t e s the i n f l u e n c e of charge weight per delay on the l a t e r a l extent of damage t o the rockmass. 116 16 w 14 o 2 12 o < 10 -I «* a u. 8 x UJ b • < a < 2 Figure 8.3 R • /~w" ( V / K ) l / B V • 100 i n / t K » 2 0 0 B • - 1 . 6 T 1 1 1 1 i I 1 1 10 2 0 3 0 4 0 50 6 0 7 0 8 0 9 0 E X P L O S I V E C H A R G E P E R D E L A Y (lb) too I f b l a s t i n g t r i a l s i n d i c a t e that a s i g n i f i c a n t improvement i n bermface angle can be a t t a i n e d by m o d i f i c a t i o n of the b l a s t i n g p a t t e r n then economic rewards of a steeper p i t may j u s t i f y the purchase of a s m a l l diameter d r i l l f o r l i n e h o l e s . Such a d r i l l should have the c a p a c i t y t o d r i l l holes up t o 25°off v e r t i c a l . I f a l l holes i n the t r i m b l a s t were i n c l i n e d p a r a l l e l t o the f i n a l face the burden would be of constant t h i c k n e s s from top t o bottom. As a r e s u l t , the r e f l e c t e d t e n s i l e wave would form crack s t h a t would be p a r a l l e l t o the f i n a l f a c e , r e s u l t i n g i n a smoother u l t i m a t e w a l l . The D-2 d r i l l should be used on a l l t r i m p a t t e r n s because i t has the narrow 7 7/8" d r i l l s t e e l . The l i m i t e d charge i n the t r i m b l a s t w i l l form a 31% higher e x p l o s i v e column i n the b l a s t hole than i f the 9" d r i l l holes were u t i l i z e d . T h i s i s d e s i r a b l e because the e x p l o s i v e f o r c e i s d i s t r i b u t e d over a greater area of the rockmass. 117 8.4.3 Reduction of Burden i n Line Holes Because the l i n e holes should p e e l away from the rock between the f i n a l b u f f e r row they must not be h e a v i l y burdened. Burden thicknesses quoted i n l i t e r a t u r e are c o n s i s t e n t l y smaller than the l i n e hole spacing, e.g. 0.5 t o 0.8 of spacing. The i n f l u e n c e of reduced burden should a l s o be evaluated i n the o p t i m i z a t i o n t r i a l s . A d i s t a n c e of 2.0 m between the l i n e hole and the f i r s t b u f f e r row w i l l be a good s t a r t i n g p o i n t f o r the t r i a l . 8.4.4 I n f l u e n c e of Rock Conditions The performance of an e x p l o s i v e i s very dependent on the mechanical p r o p e r t i e s of the rockmass, e s p e c i a l l y on shear s t r e n g t h , e l a s t i c modulus, and frequency of d i s c o n t i n u i t i e s . There are two p r i n c i p a l rock types i n the Main zone p i t : i n t r u s i v e gabbro and p y r o c l a s t i c s . The p o i n t load t e s t i n g program has shown th a t the i n t a c t gabbro i s 2 t o 4 times stronger than the v o l c a n i c rocks. U n i a x i a l compression t e s t s would l i k e l y i n d i c a t e t h a t the gabbro i s a l s o much s t i f f e r . I n - p i t s t r u c t u r a l mapping and observations of R.Q.D. i n bore holes has shown th a t d i s c o n t i n u i t i e s i n the v o l c a n i c s are c l o s e r spaced. B l a s t i n g design should r e f l e c t these d i f f e r e n c e s i n the rockmass. The s t r o n g e r , s t i f f e r rock u s u a l l y r e q u i r e s more e x p l o s i v e energy t o a t t a i n e q u i v a l e n t fragmentation. The same p a t t e r n and powder f a c t o r i s used i n a l l production b l a s t s i n the Main zone. B l a s t i n g t e s t s should be c a r r i e d out t o determine the optimum powder f a c t o r f o r each rock type. The same powder f a c t o r s should then be used i n the t r i m b l a s t s . 118 The p r e - s p l i t c o n t r o l l e d b l a s t i n g technique has proven very e f f e c t i v e i n c o n t r o l l i n g b l a s t damage t o the f i n a l w a l l on numerous c i v i l p r o j e c t s . The p r e - s p l i t b l a s t i n g p a t t e r n i s s i m i l a r t o the cushion b l a s t p a t t e r n i l l u s t r a t e d i n Figure 8.2, but the i n i t i a t i o n sequence i s q u i t e d i f f e r e n t . C l o s e l y spaced, decoupled charges i n the l i n e holes are detonated f i r s t without any delay. Note that the Hercudet i n i t i a t i o n system cannot be used i n the l i n e holes because the r e l a t i v e l y low burning speed of the gas mixture causes a delay between each b l a s t h o l e . Reinforcement of P-waves from adjacent b l a s t holes and high gas pressures f a i l the rock i n t e n s i o n along a plane p a r a l l e l t o the row of l i n e h o l e s . Because the b l a s t i s g r e a t l y overburdened extremely high gas pressures are generated i n the l i n e h o l e s . The gases penetrate the p r e - s p l i t crack and open i t s l i g h t l y as they escape t o s u r f a c e . A f t e r the p r e - s p l i t crack i s e s t a b l i s h e d the remaining b u f f e r l i n e s are detonated i n the standard sequence. The p r e - s p l i t crack w i l l not prevent the compressive P-wave from p e n e t r a t i n g i n t o the w a l l s , but i t w i l l provide a vent by which e x p l o s i v e gases can escape. As a r e s u l t , r a d i a l cracks generated by hoop s t r e s s e s induced by the expanding gases w i l l not propagate beyond the p r e - s p l i t plane nor w i l l the gases open up any e x i s t i n g d i s c o n t i n u i t i e s . The o v e r a l l r e s u l t w i l l be a much more i n t a c t rockmass. I t i s recommended that the p r e - s p l i t detonation method be t e s t e d i n the gabbro. A l i n e of twenty holes should be d r i l l e d . The i n i t i a l t e s t should not be c a r r i e d out i n the u l t i m a t e p i t w a l l i n case the gases vent along e x i s t i n g j o i n t s i n s t e a d of opening the p r e - s p l i t plane. The holes should be l i g h t l y loaded. Decoupling should be 119 achieved w i t h 2 inch i n t e r n a l diameter p l a s t i c p i p e. The type of e x p l o s i v e should be s e l e c t e d w i t h the a s s i s t a n c e of the b l a s t i n g c o n t r a c t o r . Spacing of the l i n e holes should be between 1.5 and 2.1 m. The b l a s t should be inspected p r i o r t o detonation of the b u f f e r rows t o see i f the p r e - s p l i t crack has formed. I f the p r e - s p l i t method c r e a t e s a b e t t e r f i n a l w a l l then the t r a d i t i o n a l cushion b l a s t i n g i t should be u t i l i z e d because the s t a b i l i t y s t u d i e s i n d i c a t e that there are numerous continuous j o i n t s i n the rockmass t h a t could act as r e l e a s e surface f o r berm s c a l e f a i l u r e s . By reducing b l a s t damage on the f a i l u r e planes the shear s t r e n g t h can be maintained at near peak l e v e l s , i n c r e a s i n g the s t a b i l i t y of the p o t e n t i a l f a i l u r e s . 8.4.5 Hercudet I n i t i a t i o n System The Hercudet i n i t i a t i o n system i s p r e s e n t l y being evaluated f o r use i n a l l production b l a s t s . The system has s e v e r a l o p e r a t i o n a l advantages over conventional s a f e t y fuse delay systems i n c l u d i n g : s i m p l i c i t y and ease of o p e r a t i o n , c o s t , t e s t i n g of the c i r c u i t p r i o r t o d e t o n a t i o n , and the p o t e n t i a l of d e s e n s i t i z i n g the system a f t e r i t has been charged. The most favourable c h a r a c t e r i s t i c of the system from a s t a b i l i t y p o i n t of view i s the inherent delay between every b l a s t hole. In the Hercudet system b l a s t i n g caps" are connected by p l a s t i c tubes that are charged w i t h an e x p l o s i v e gas mixture. The flame f r o n t t r a v e l s at 2500 m/s through the p l a s t i c t u b i n g , and i n i t i a t e s every cap hooked i n t o the c i r c u i t . In a standard production b l a s t p a t t e r n approximately 15 m of t u b i n g w i l l extend between caps i n adjacent h o l e s . As a r e s u l t , the 120 detonation of consecutive b l a s t holes w i l l be delayed by a minimum of 6 ms. I f a d d i t i o n a l delay i s r e q u i r e d e x t r a tubing can be plac e d between the h o l e s , e.g. 2.5 m per 1 ms. The Hercudet system should a l s o be used i n t r i m b l a s t s i f i t proves e f f e c t i v e i n production b l a s t s because adequate delays are e s p e c i a l l y important near the f i n a l face. The goal of any c o n t r o l l e d b l a s t i n g procedure i s t o reduce the e x p l o s i v e energy r e l e a s e d t o one hole per delay (unless p r e - s p l i t t i n g ) . The Hercudet system w i l l guarantee t h a t t h i s g o a l i s achieved. 8.4.6 F i r i n g Order and Confinement To minimize the amount of b l a s t energy going i n t o the f i n a l w a l l and t o a t t a i n maximum fragmentation i t i s important t h a t a l l holes be f r e e faced at the time of e x p l o s i o n . The f r e e face r e f l e c t s the P-wave i n t o a t e n s i l e wave th a t does most of the fragmentation. I f a hole i s overburdened the gases and fragmented muck cannot expand outward toward the f r e e face. Higher gas pressures are developed, opening r a d i a l cracks that may extend w e l l beyond the f i n a l d i g l i n e . Energy t h a t would have been d i s s i p a t e d during the expansion i s i n s t e a d r e d i r e c t e d i n t o the f i n a l w a l l as a higher energy s e i s m i c wave. In summary, b l a s t i n g next t o a f r e e face r e s u l t s i n b e t t e r fragmentation o f muck and l e s s gas and v i b r a t i o n damage t o the f i n a l w a l l . Therefore, i t i s important that no u l t i m a t e w a l l t r i m s are choked b l a s t s or s i n k i n g c u t s . The recommended detonation sequencing i s i l l u s t r a t e d i n Figure 8.4A. An a l t e r n a t e detonation sequence that e s t a b l i s h e s the f r e e face at 90° to the u l t i m a t e w a l l should a l s o be t e s t e d . This f i r i n g sequence has 121 the advantage that any constructive reinforcement of seismic waves and propagation of the reflected tensile wave that causes most of the damage w i l l be parallel to the f i n a l wall and not into i t . The f i r i n g order is illustrated in Figure 8.4B. This technique is effective i f a large number of buffer rows is used because a well defined free face w i l l be established. Because only two buffer rows are used at Equity the technique may not prove as successful as the standard i n i t i a t i o n method. 100 ms dslay I S a°2 & 2 ° 4 2 ° 5 2 ° 8 ' ' ' b u f f e r s 100 ms dslay L I.I Figure 8.4.A PRESENT DETONATION SEQUENCE 23 ms dtlays bstwson holts START>-0 - O — O — — — o - 0 '•' ' 2 1.3 XA Yi 8 1 82 8.3 8 4 8.3 86 87 8 9 TP holes buffer rows >•' * l 3.1 4.1 5.1 6.1 7.1 25 ms dslays on diagonals Figure 8 . 4 . B DETONATION SEQUENCE THAT CREATES FREE FACE PERPENDICULAR TO WALL 122 9.0 EVALUATION OF PIT SLOPE STABILITY 9.1 PARAMETERS THAT INFLUENCE STABILITY Throughgoing d i s c o n t i n u i t i e s , water c o n d i t i o n s , shear s t r e n g t h , and b l a s t i n g a l l i n f l u e n c e p i t w a l l s t a b i l i t y . The most important v a r i a b l e i n t h i s l i s t i s g e o l o g i c s t r u c t u r e . In a l l but the weakest rocks f a i l u r e can only occur i f some p r e - e x i s t i n g weakness i s present i n the rockmass on which the f a i l u r e can occur. A wedge bounded by two d i s c o n t i n u i t i e s i s the most common f a i l u r e type. F a i l u r e w i l l only occur i f the l i n e of i n t e r s e c t i o n of the two planes plunges at an angle shallower than the angle of the s l o p e , i . e . the f a i l u r e d a y l i g h t s . To determine whether there i s p o t e n t i a l f o r a f a i l u r e the s t r u c t u r a l f a b r i c of the rockmass must be w e l l understood. In the Main Zone the dominant d i s c o n t i n u i t y o r i e n t a t i o n s i n each of the four s t r u c t u r a l domains have been a c c u r a t e l y e s t a b l i s h e d by l i n e mapping and s t a t i s t i c a l a n a l y s i s . At t h i s p o i n t , a l l p o s s i b l e combinations of planes must be evaluated t o see i f they w i l l d a y l i g h t out of a slope of given geometry. The Main Zone p i t has been d i v i d e d i n t o 10 zones of c o n s i s t e n t g e o l o g i c s t r u c t u r e and p i t w a l l geometry. These zones are c a l l e d Design Sectors. Any d i s c o n t i n u i t i e s t h a t d a y l i g h t out of the slope have p o t e n t i a l f o r f a i l u r e . They are c a l l e d " k i n e m a t i c a l l y p o s s i b l e " f a i l u r e modes. F a i l u r e can occur by s e v e r a l d i f f e r e n t f a i l u r e mechanisms. These i n c l u d e : wedge pla n e , t o p p l i n g , b l o c k , a c t i v e - p a s s i v e , c i r c u l a r , and step. Only the f i r s t three mechanisms have been used t o i d e n t i f y k i n e m a t i c a l l y 123 p o s s i b l e f a i l u r e modes i n t h i s study because they are the most common f a i l u r e types i n open p i t mine environments. A p i t could be designed on the c r i t e r i o n t h a t "no f a i l u r e modes s h a l l d a y l i g h t out of the slo p e " . This approach i s extremely co n s e r v a t i v e because not a l l k i n e m a t i c a l l y p o s s i b l e f a i l u r e modes w i l l be unstable and a sm a l l number of f a i l u r e s can be t o l e r a t e d i n a mine environment, i f under c o n t r o l l e d c o n d i t i o n s . S t a b i l i t y w i l l depend on wedge geometry, shear s t r e n g t h on the f a i l u r e plane, and groundwater c o n d i t i o n s . The e f f e c t of these parameters was discussed i n d e t a i l i n i n e a r l i e r s e c t i o n s of t h i s r e p o r t . A more reasonable design approach i s t o i d e n t i f y a l l k i n e m a t i c a l l y p o s s i b l e f a i l u r e modes and determine t h e i r approximate s t a b i l i t y . When a k i n e m a t i c a l l y p o s s i b l e f a i l u r e i s i d e n t i f i e d as very s t a b l e , m a r g i n a l l y s t a b l e , or unstable a b e t t e r d e c i s i o n can be made on the slope angle. I f the f a i l u r e i s s t a b l e the slope can be steepened f u r t h e r . I f i t w i l l be unstable the slope should be designed so the f a i l u r e does not d a y l i g h t unless the p r o b a b i l i t y of an a c t u a l f a i l u r e i s s u f f i c i e n t l y remote t o j u s t i f y the r i s k of l e t t i n g i t d a y l i g h t . I f i t i s m a r g i n a l l y s t a b l e the slope can e i t h e r be f l a t t e n e d or some other remedial measure taken t o increase s t a b i l i t y . 9.2 Methods and Assumptions Used i n Design The design process used t o determine the maximum safe slope and berm face angle i n each design s e c t o r i s summarized below i n p o i n t form: 124 1. Determine average plunge d i r e c t i o n of p i t w a l l . 2. Place p i t geometry o v e r l a y on F a i l u r e Modes f i g u r e f o r app r o p r i a t e s t r u c t u r a l domain. 3. Determine maximum o v e r a l l slope f o r which no f a i l u r e s w i l l d a y l i g h t . - i f f a i l u r e s d a y l i g h t at slopes < 50* c a l c u l a t e F.O.S. f o r f a i l u r e mode. Assume c=10.5 kPa, 0=31°, f a i l u r e height of 50 m, dry c o n d i t i o n . - i f F.O.S. > 2 f a i l u r e i s s t a b l e under a l l c o n d i t i o n s and can be allowed t o d a y l i g h t . - i f 1 < F.O.S. < 2 f a i l u r e i s m a r g i n a l l y s t a b l e and s e n s i t i v i t y of water must be c a l c u l a t e d . Assume maximum average water pressure of 33 kPa f o r 50 m high s l o p e . - i f groundwater causes F.O.S. t o drop below 1.1 recommend dewatering i n design s e c t o r . - i f F.O.S. < 1 f a i l u r e w i l l be unstable. Evaluate p r o b a b i l i t y of occurence based on s i z e o f d i s c o n t i n u i t y groups forming the two f a i l u r e s u r f a c e s . - i f p r o b a b i l i t y high f a i l u r e should not d a y l i g h t . - i f p r o b a b i l i t y low p o t e n t i a l hazard should be noted but the slope can be steepened t o a l l o w f a i l u r e t o t o d a y l i g h t . 4. I f no f a i l u r e modes d a y l i g h t below 50°stability w i l l be c o n t r o l l e d by berm f a i l u r e . - i f any f a i l u r e modes d a y l i g h t below 65°berm face evaluate p r o b a b i l i t y of those berm f a i l u r e s o ccuring based on s i z e of d i s c o n t i n u i t y group. - i f p r o b a b i l i t y high f l a t t e n berm face. - i f p r o b a b i l i t y low maintain berm face at present value and note p o s s i b i l i t y of berm f a i l u r e s . - some berm f a i l u r e s can be t o l e r a t e d as long as adequate catchment i s provided by benches below. 125 5. I f no berm f a i l u r e s e x i s t s t a b i l i t y w i l l be c o n t r o l l e d by maximum berm face angle that can be maintained by the rockmass. - examine o r i e n t a t i o n of minor j o i n t s . - evaluate p o t e n t i a l f o r step f a i l u r e on minor j o i n t s . - design berm at maximum angle that can be maintained, p r e s e n t l y 60-66° . 6. Check c o m p a t i b i l i t y of design. - The berm face angle must be s u f f i c i e n t l y steep t o a l l o w an 8 m wide berm every 20 m i n e l e v a t i o n . I f t h i s cannot be achieved the o v e r a l l slope angle must be f l a t t e n e d . 9.3 DESIGN SECTORS This s e c t i o n presents a b r i e f s t a b i l i t y e v a l u a t i o n of each design s e c t o r . Recommended slope angles, most l i k e l y f a i l u r e modes, and expected groundwater c o n d i t i o n s are b r i e f l y d iscussed. I f s t a b i l i t y of the design s e c t o r c o u l d improve from drainage then some form of a dewatering system i s recommended. The most important design conclusions presented i n the f o l l o w i n g 10 subsections are summarized i n Table 9.1 on the f o l l o w i n g page. Figure 9.1 shows the l o c a t i o n o f each design s e c t o r i n the Main zone. 126 Table 9.1 SUMMARY OF DESIGN PARAMETERS Sector W a l l Angle Berm Face C o n t r o l l i n g Groundwater Drainage (deg) (deg) F a i l u r e Mode Co n d i t i o n 1 50 66 step very favourable no 2 49 64 step mod. unfavourable yes 3 49 64 step/berm very unfavourable yes wedge 4 45 59 f u l l w a l l unfavourable yes wedge 5 45 59 berm wedge unfavourable yes 6 46 60 berm plane unfavourable yes 7 50 66 step mod. favourable no 8 50 66 step favourable no 9 46 60 f u l l w a l l unfavourable yes wedge 10 45 59 f u l l w a l l mod. unfavourable yes wedge Figure 9.1 MAIN ZONE DESIGN SECTORS 127 9.3.1 Design Sector S - l STRUCTURAL DOMAIN DIP DIRECTION ROCK TYPE WATER CONDITION D l 045' v o l c a n i c s very favourable OVERALL PIT ANGLE - 50° BERM FACE ANGLE - 66° STABILITY EVALUATION: S t a b i l i t y of berm face c o n t r o l s the o v e r a l l p i t w a l l angle i n t h i s design s e c t o r . No k i n e m a t i c a l l y p o s s i b l e f a i l u r e modes c o n t r o l l e d by major d i s c o n t i n u i t i e s have been i d e n t i f i e d . S t a b i l i t y of the berm w i l l be c o n t r o l l e d by p e r s i s t e n t s e t s of minor j o i n t s that d i p approximately 35°out of the s l o p e . The j o i n t s are not continuous; as a r e s u l t a step f a i l u r e c o n d i t i o n develops. In areas where step f a i l u r e occurs berm angles of 60° t o 65°degrees have been measured i n the f i e l d . The recommended p i t w a l l angle i s based on maintaining a 66* berm face. Figure 9.2 i s a stereographic p l o t of g e o l o g i c a l s t r u c t u r e and p i t geometry i n t h i s s e c t o r . COMMENTS: Because t h i s s e c t o r i s l o c a t e d on the west s i d e of the p i t , opposite the major groundwater recharge areas, the groundwater c o n d i t i o n s are expected t o be very favourable. Dewatering should not be necessary. Only l i m i t e d p i t w a l l exposures were a v a i l a b l e i n t h i s s e c t o r i n 1984 (a t o t a l of only four t r a v e r s e s ) . As a r e s u l t , the design i s a l s o based on s t r u c t u r a l i n f o r m a t i o n c o l l e c t e d i n S-2 and S-3. A d d i t i o n a l l i n e mapping and a n a l y s i s w i l l be r e q u i r e d t o v e r i f y the present design as soon as adequate exposures are excavated. 128 9.3.2 Design Sector S-2 STRUCTURAL DOMAIN DIP DIRECTION ROCK TYPE WATER CONDITION D l 020° v o l c a n i c s moderate t o unfavourable OVERALL PIT ANGLE BERM FACE ANGLE 49° 64° STABILITY EVALUATION: Most major s t r u c t u r e s s t r i k e perpendicular t o w a l l or d i p s t e e p l y i n t o i t . No l a r g e s c a l e f a i l u r e s on major d i s c o n t i n u i t i e s are anticipated.'. Step f a i l u r e and l o c a l i z e d t o p p l i n g f a i l u r e on berm s c a l e w i l l c o n t r o l slope s t a b i l i t y i n t h i s design s e c t o r . The p i t w a l l design i s based e on a maximum bermface angle of 64 t h a t i s p r e s e n t l y maintained i n t h i s M o d i f i c a t i o n s t o t r i m b l a s t i n g procedures may improve rockmass c o n d i t i o n i n the f i n a l w a l l . I f berms can be maintained at 70° the o v e r a l l slope i n c r e a s e o v e r a l l s t a b i l i t y . Poor groundwater c o n d i t i o n s w i l l be encountered at depth; t h e r e f o r e , i t i s recommended that drainage be i n s t a l l e d t o reduce the d e s t a b i l i z i n g f o r c e s of excess f l u i d pressure. s e c t o r . COMMENTS: e can be steepened t o 53. Concavity of the p i t i n t h i s s e c t o r w i l l 129 N 130 9.3.3 Design Sector S-3 STRUCTURAL DOMAIN DIP DIRECTION ROCK TYPE WATER CONDITION D l 320° v o l c a n i c s very unfavourable OVERALL PIT ANGLE BERM FACE ANGLE 49° 64° STABILITY EVALUATION: P i t w a l l angle i s c o n t r o l l e d by the maximum angle of berm face t h a t can be maintained i n the v o l c a n i c rocks except i n the northern p o r t i o n of the design s e c t o r . There, s t e e p l y d i p p i n g wedges formed by planes B, C, and D begin t o d a y l i g h t out of the berm i f i t i s steeper than 60 . Because no discontinuous j o i n t i n g i s observed p a r a l l e l t o the slope i n t h i s design s e c t o r step f a i l u r e problems are not a n t i c i p a t e d and the berms w i l l remain s t a b l e at 64 . In the northern p o r t i o n o f the se c t o r wedges 1 and 2 w i l l s t a r t t o d a y l i g h t i f berm face angles exceed 48* . To reduce the volume of any berm f a i l u r e s and t o minimize the p o t e n t i a l f o r f u l l w a l l f a i l u r e on these planes the berm face angle should be reduced t o 60°, r e s u l t i n g i n a 46° o v e r a l l slope i n that area. A slope r e d u c t i o n i s a l s o r e q u i r e d i n t h i s s e c t o r t o serve as a t r a n s i t i o n zone between S-2 at 49° and S-4 at 45°. Figure 9.4 i l l u s t r a t e s p i t geometry and expected f a i l u r e modes i n t h i s design s e c t o r . COMMENTS: Groundwater c o n d i t i o n s are very unfavourable i n t h i s domain. Large q u a n t i t i e s of recharge are expected t o fl o w i n t o the p i t through t h i s s e c t o r because the v o l c a n i c s are much more permeable than the gabbro. The water t a b l e i n the upper p o r t i o n of t h i s s e c t o r i s w i t h i n 20 m of 131 s u r f a c e . In the p i t seepage has been observed at 1290 m e l e v a t i o n , suggesting t h a t the water t a b l e i s at s u r f a c e at t h i s depth i n the p i t . Because higher water pressures w i l l occur as mining progresses t o depth a drainage system should be i n s t a l l e d i n t h i s design s e c t o r . The drainage w i l l i n t e r c e p t a l a r g e q u a n t i t y of i n f l o w s i n t o the p i t . I t w i l l a l s o reduce the d e s t a b i l i z i n g f o r c e s of water on any p o t e n t i a l f a i l u r e s . Concavity of t h i s design s e c t o r w i l l c o n t r i b u t e t o o v e r a l l s t a b i l i t y of major f a i l u r e s . N F i g u r e 9.4 DESIGN SECTOR S-3 132 9.3.4 Design Sector S-4 STRUCTURAL DOMAIN DIP DIRECTION ROCK TYPE WATER CONDITION D2 275° gabbro unfavourable (very unfavourable at depth) OVERALL PIT ANGLE - 45° BERM FACE ANGLE - 59° STABILITY EVALUATION: Design s e c t o r S-4 has the g r e a t e s t p o t e n t i a l f o r developing i n s t a b i l i t y i n the Main Zone p i t . F a i l u r e w i l l occur on plane A t h a t s t r i k e s 267°, p a r a l l e l t o the p i t w a l l s , The mean d i p i s 51° i n t o the p i t . The mode of f a i l u r e w i l l be e i t h e r planar or an a s s y m e t r i c a l wedge formed by plane A and one of the s t e e p l y d i p p i n g d i s c o n t i n u i t y s e t s t h a t s t r i k e near 90° t o the p i t w a l l (e.g. C & D i n Figure 9.5). S e v e r a l berm f a i l u r e s that have t h i s o r i e n t a t i o n have already been observed. Because the mean angle of plunge f o r wedge 3 i s 50* there i s no way t o prevent berm f a i l u r e s unless the face angle i s reduced t o u n r e a l i s t i c l e v e l s (e.g. 45°). The design g o a l i n t h i s sector i s t o minimize the p o t e n t i a l of a multiberm f a i l u r e . T his can be achieved i f the o v e r a l l p i t slope angle i s maintained at 45° and the berm face i s excavated at 59° . An adequate berm 8 m wide must be maintained every 20 m i n e l e v a t i o n t o c o n f i n e any berm f a i l u r e s . The three most l i k e l y f a i l u r e modes i n t h i s domain are shown i n Figure 9.5. Because the s t a t i s t i c a l d i s t r i b u t i o n of d i p s on planes i n group A i s broad (see Figure 9.6), there i s a p o s s i b i l i t y of a multi-berm f a i l u r e i n t h i s s e c t o r even at the 45° o v e r a l l slope angle. The f a i l u r e would of course occur on one of the f l a t t e r d i s c o n t i n u i t i e s i n group A. COMMENTS: 133 Figure 9.6 STATISTICAL DISTRIBUTION OF DIP ON GROUP A PLANES ALL MAJOR STRUCTURES IN DOMAIN D ' Z . 2 0 -| 37 39 41 43 45 47 4 9 31 33 33 37 5 9 61 63 63 67 69 71 73 73 DIP ANGLE 134 A drainage system that reduces pore pressure behind the u l t i m a t e w a l l w i l l s i g n i f i c a n t l y decrease the p r o b a b i l i t y of a l a r g e f a i l u r e . For example, a 50 m high wedge bounded by one of the f l a t t e r planes i n group A (40 < >/267 o) and plane C (83°/173°) w i l l be very unstable (F.O.S.=0.81) i f the average water pressure on the f a i l u r e s u r f aces exceeds 16.5 kPa, o n l y one f i f t h of the t h e o r e t i c a l maximum value and eq u i v a l e n t t o a maximum pressure head of only 10 m somewhere near the center of the wedge. I f the water can be drained the wedge w i l l be s t a b l e w i t h a f a c t o r of s a f e t y of 1.08. The s t a b i l i t y a n a l y s i s assumed shear s t r e n g t h parameters presented i n S e c t i o n 7.3. The WIP GraD drainage system w i l l be the most e f f e c t i v e method of reducing water pressures i n t h i s design sec t o r because c l o s e l y spaced w e l l s w i l l be r e q u i r e d t o achieve s u f f i c i e n t l y r a p i d drainage i n the low p e r m e a b i l i t y gabbro. The cu r r e n t east u l t i m a t e p i t w a l l i s s l i g h l t y convex. S t a b i l i t y w i l l be reduced somewhat because l e s s l a t e r a l confinement w i l l be provided on any planar f a i l u r e . As the convexity i s very broad the d e s t a b i l i z i n g i n f l u e n c e w i l l not be as severe as i n the Southern T a i l p i t where l a r g e f a i l u r e s occured on both convex lobes. 135 Design Sector S-5 STRUCTURAL DOMAIN - D3 DIP DIRECTION - 270° ROCK TYPE - v o l c a n i c s WATER CONDITION - unfavourable OVERALL PIT ANGLE - 45" BERM FACE ANGLE - 59° STABILITY EVALUATION: S t a b i l i t y i n t h i s design s e c t o r i s c o n t r o l l e d by s t a b i l i t y of the berms. Berm f a i l u r e s are expected on f a i l u r e modes 4, 6 and 12 (see Figure 9.7). A l l of these f a i l u r e modes plunge q u i t e s t e e p l y (peak plunges 56°- 60°) t o d a y l i g h t out of the o v e r a l l slope so multi-berm f a i l u r e s w i l l not occur on these d i s c o n t i n u i t i e s . Wedge 3 i s the only f a i l u r e mode i n t h i s s e c t o r t h a t can d a y l i g h t out of the o v e r a l l s l o p e . Because i t i s a very t h i n , overhanging wedge plunging only 35°, i t w i l l not pose s t a b i l i t y problems (F.O.S. under dry c o n d i t i o n = 5.03). P i t w a l l design i s based on minimizing the number of berm f a i l u r e s by reducing the berm face angle t o 59°. With the c o n s t r a i n t of a 59° berm face and an 8 m wide berm every 20 m i n e l e v a t i o n t o c o n t a i n r a v e l l i n g the maximum p i t slope angle t h a t can be maintained i s 45°. COMMENTS: Groundwater c o n d i t i o n s are expected t o be unfavourable i n t h i s s e c t o r because the water t a b l e w i l l be at or c l o s e t o the surface deep i n the p i t . The Bessemer Creek dyke package i s l o c a t e d i n the center of t h i s s e c t o r . The dyke package i s expected t o act as a s u b s t a n t i a l groundwater discharge area. To minimize the amount of surface water e n t e r i n g t h i s s e c t o r a l l east w a l l d i v e r s i o n d i t c h e s must be f u l l y l i n e d . Drainage should be considered i n t h i s s e c t o r t o improve 136 s t a b i l i t y of any multi-berm f a i l u r e modes that c o u l d develop and t o capture as much of the incoming water so the water t a b l e on the p i t f l o o r can be p u l l e d down. The s l i g h t convexity of the u l t i m a t e p i t w a l l i n t h i s s e c t o r w i l l have a minor d e s t a b i l i z i n g i n f l u e n c e . Figure 9.7 DESIGN S E C T O R S-3 137 9.3.6 Design Sector S-6 STRUCTURAL DOMAIN ' - D3 DIP DIRECTION - 180° ROCK TYPE - v o l c a n i c s WATER CONDITION - unfavourable OVERALL PIT ANGLE - 46* BERM FACE ANGLE - 60° STABILITY EVALUATION: Some s t a b i l i t y problems must be expected i n design s e c t o r S-6. The most dominant d i s c o n t i n u i t y trend s t r i k e s s u b - p a r a l l e l t o the p i t w a l l . The peak d i p i s 60° so berm f a i l u r e s must be expected on the f l a t t e r d i s c o n t i n u i t i e s w i t h i n t h i s group. The berm face was designed at the same i n c l i n a t i o n as the peak d i p of plane A so any f a i l u r e s t h a t do form w i l l be contained e a s i l y by the catchment berms because they w i l l be t h i n s l i v e r s . O v e r a l l p i t w a l l s t a b i l i t y w i l l be c o n t r o l l e d by f a i l u r e modes 8 and 11 t h a t w i l l r e l e a s e on plane D (see Figure 9.8). Plane D i s very unfavourably o r i e n t e d , d i p p i n g at 35°out of the s l o p e . As a r e s u l t , any continuous d i s c o n t i n u i t i e s w i t h t h i s o r i e n t a t i o n w i l l d a y l i g h t out of the o v e r a l l p i t slope and c o u l d r e s u l t i n multi-berm f a i l u r e s . Reduction of the o v e r a l l s l o p e angle below 45°to l i m i t f a i l u r e s 8 and 11 i s not p r a c t i c a l because plane D i s not a dominant o r i e n t a t i o n . Rather, the s e c t o r should be designed at 45*and any loose wedges should be removed or some form of remedial measures should be a p p l i e d t o increase the s t a b i l i t y . 138 COMMENTS: This sector has considerable potential for a multiberm failure on plane D. A s t a b i l i t y evaluation of wedge 8 gives a factor of safety of 1.04 under dry conditions and only 0.88 with water present (assuming O 0=31, c=10.5 kPa, slope height 50 m, average water pressure = 16.5 kPa, equivalent to a maximum head of 10 m). The analysis clearly indicates that reduction of water pressure w i l l lower the potential for a multi-berm failure considerably. Any in s t a b i l i t y that does develop w i l l then require only minimal support to increase the F.O.S. above 1.1. The p i t walls in this design sector w i l l be tightly concave. The concavity w i l l also help to increase s t a b i l i t y of the larger failures because i t w i l l provide an element of lateral confinement. N x 139 9.3.7 Design Sector S-7 STRUCTURAL DOMAIN DIP DIRECTION ROCK TYPE WATER CONDITION D3 115° v o l c a n i c s moderately favourable OVERALL PIT ANGLE - 50° BERM FACE ANGLE - 66° STABILITY EVALUATION: Design i n t h i s s e c t o r i s c o n t r o l l e d by the maximum berm angle that can be maintained. Figure 9.9 shows the o r i e n t a t i o n s of the major s t r u c t u r a l trends i n t h i s s e c t o r . As a l l major s t r u c t u r e s s t r i k e very o b l i q u e l y t o the w a l l there appears t o be no danger of a major berm f a i l u r e . The only k i n e r n a t i c a l l y p o s s i b l e f a i l u r e wedge (9) was analyzed by program SWEDGE. The f a c t o r s of s a f e t y were 2.43 f o r a dry slope and 1.13 f o r a slope w i t h an average water pressure of 33 mPa (20 m maximum head). The wedge should not present any s t a b i l i t y problems. The d i s c o n t i n u i t y groups do not combine t o form any berm s c a l e f a i l u r e s . P i t w a l l s i n t h i s design s e c t o r should be very s t a b l e . As a r e s u l t the p i t w a l l design i s based on m a i n t a i n i n g the maximum berm face angle t h a t appears t o be s t a b l e i n the v o l c a n i c rocks of the Main Zone. This angle i s 66*. COMMENTS: Favourable groundwater c o n d i t i o n s and c o n c a v i t y w i l l both improve o v e r a l l s t a b i l i t y . Drainage should not be r e q u i r e d unless monitoring i n d i c a t e s t h a t high pore pressures are developing. According t o the l a t e s t p i t design the main haul road w i l l be l o c a t e d on the west w a l l of the p i t . The l o c a t i o n i s very favourable i n terms of s t a b i l i t y c o n s i d e r a t i o n s and no f a i l u r e s should threaten the haul road during 140 the l i f e of the mine according t o c u r r e n t l y a v a i l a b l e data. I t i s important t o note that the design i n t h i s s e c t o r was based on inf o r m a t i o n c o l l e c t e d s e v e r a l hundred meters away i n design s e c t o r S-5. L i n e mapping and a n a l y s i s must be c a r r i e d out i n S-7 when one or two benches become exposed t o confirm the v a l i d i t y of the present design before a l a r g e p o r t i o n of the u l t i m a t e p i t w a l l i s excavated. N Flgur« 9.9 DESIGN SECTOR S-7 141 9.3.8 Design Sector S-8 STRUCTURAL DOMAIN DIP DIRECTION ROCK TYPE WATER CONDITION D3 090° v o l c a n i c s favourable OVERALL PIT ANGLE - 50° BERM FACE ANGLE - 66° STABILITY EVALUATION: Design s e c t o r S-8 i s expected t o be the most s t a b l e s e c t o r i n the Main zone p i t . A v a i l a b l e data i n d i c a t e s t h a t a l l major s t r u c t u r e s plunge i n t o the w a l l . No multi-berm f a i l u r e s are expected. Some berm f a i l u r e s w i l l l i k e l y develop on random j o i n t i n g but no unfavourable s t r u c t u r a l trends t h a t would combine t o form s t e e p l y d i p p i n g wedges plunging i n t o the p i t have been i d e n t i f i e d . P i t w a l l angle i s going to be c o n t r o l l e d by the maximum angle t h a t can be maintained on the berms. The design c a l l s f o r a 66 berm face. Groundwater c o n d i t i o n s i n t h i s s e c t o r are expected t o be very favourable, the e n t i r e w a l l should d r a i n a f t e r a p e r i o d of time. The main haul road w i l l be developed i n t h i s design s e c t o r . The l o c a t i o n i s i d e a l because the p r o b a b i l i t y of a multi-berm f a i l u r e t h a t would d i s r u p t operations i s remote. I f refinements t o the present t r i m b l a s t i n g procedure r e s u l t i n a more i n t a c t rockmass that can maintain a 70°berm face then there w i l l be f u r t h e r p o t e n t i a l f o r steepening the o v e r a l l slope i n t h i s s e c t o r . The s t r u c t u r a l data used f o r the design was c o l l e c t e d i n s e c t o r S-5, s e v e r a l hundred meters away on the opposite s i d e of the p i t because no exposures were a v a i l a b l e i n S-8 i n 1984. Because the COMMENTS: 142 s t r u c t u r a l f a b r i c can vary s i g n i f i c a n t l y over t h i s d i s t a n c e a d d i t i o n a l l i n e mapping must be c a r r i e d out t o f i n a l i z e the u l t i m a t e p i t w a l l design i n S - 8 . Figure 9.10 DESIGN SECTOR S-8 143 9.3.9 Design Sector S-9 STRUCTURAL DOMAIN DIP DIRECTION ROCK TYPE WATER CONDITION D4 270° gabbro/volcanics unfavourable OVERALL PIT ANGLE - 45° BERM FACE ANGLE - 60° STABILITY EVALUATION: U n l i k e i n a l l other s e c t o r s where s t a b i l i t y i s c o n t r o l l e d by e i t h e r berm s t a b i l i t y or p o t e n t i a l f o r '.multi-berm f a i l u r e , i n sector S-9 both mechanisms have t o be considered. O v e r a l l slope angle has t o be maintained below 50 t o prevent multi-berm wedge 3 from d a y l i g h t i n g . Wedge 1 w i l l d a y l i g h t out of the o v e r a l l s l o p e ; but w i l l remain s t a b l e because i t plunges at a shallow angle of 35 . Berm s t a b i l i t y w i l l be c o n t r o l l e d by f a i l u r e s on plane C . A l l three f a i l u r e modes on plane C v a i l d a y l i g h t i f the berm face exceeds 65°. Even at the shallower berm face angle of 60° s e v e r a l of the shallower planes i n group C w i l l d a y l i g h t and cause f a i l u r e s , but these w i l l be contained on the catchment berms. Because group B d i s c o n t i n u i t i e s s t r i k e almost dead p a r a l l e l t o the p i t w a l l there i s a n a t u r a l tendency f o r the bermface t o form along these planes of weakness. The shovel operators should make an e f f o r t t o excavate t o these j o i n t s as the f i n a l berm w i l l then be smoother and there w i l l be much l e s s p o t e n t i a l f o r r a v e l l i n g . 144 COMMENTS: Piezometer monitoring i n the upper p o r t i o n s of t h i s design s e c t o r i n d i c a t e s t h a t the water t a b l e i s 20 t o 30 m below s u r f a c e , a favourable water c o n d i t i o n . However, deeper i n the p i t the water t a b l e w i l l come t o s u r f a c e and drainage should then be i n s t a l l e d t o improve the s t a b i l i t y of any multi-berm f a i l u r e modes. Groundwater i n f l o w s w i l l not be l a r g e i n t h i s s e c t o r because i t i s bounded by r e l a t i v e l y impervious gabbro on three s i d e s . P i t w a l l s i n the lower p o r t i o n of t h i s s e c t o r w i l l be i n gabbro. W e l l p o i n t s w i l l have t o be c l o s e l y spaced t o achieve adequate d e p r e s s u r i z a t i o n i f piezometers i n d i c a t e t h a t dewatering i s warranted. N Figur« 9.11 DESIGN SECTOR S-9 145 9.3.10 Design Sector S-10 STRUCTURAL DOMAIN DIP DIRECTION ROCK TYPE WATER CONDITION D4 225* v o l c a n i c s moderately unfavourable OVERALL PIT ANGLE - 45° BERM FACE ANGLE - 59° STABILITY EVALUATION: Slope angle i n t h i s design s e c t o r i s c o n t r o l l e d e x c l u s i v e l y by wedge f a i l u r e 4. This " c l a s s i c a l " wedge plunges d i r e c t l y out of the c=10.5 kPa, height of 50 m). I f the slope face exceeds 47°the wedge becomes unstable even when dry. Because the wedge i s so m a r g i n a l l y s t a b l e the o v e r a l l slope i n t h i s design s e c t o r should be f l a t t e n e d t o 44, p a r a l l e l t o the peak angle of i n t e r s e c t i o n . Berm s c a l e f a i l u r e s on wedges 3 and 4 must be expected. As the plunge angles of both wedges are shallow, wedges th a t d a y l i g h t near the bottom of the berms w i l l r e s u l t i n f a i l u r e s that w i l l take out n e a r l y the e n t i r e berm. The berm face has been designed at 59° t o l i m i t the volume of m a t e r i a l generated by the berm f a i l u r e s . COMMENTS: Drainage i s e s s e n t i a l i n t h i s s e c t o r t o increase the s t a b i l i t y of wedges t h a t w i l l d a y l i g h t out of the o v e r a l l s l o p e . As these wedges w i l l plunge shallower than wedge 3 they are l i k e l y t o be s t a b l e i f the p i t w a l l i s maintained dry but w i l l f a i l i f s i g n i f i c a n t water pressures are allowed t o b u i l d up on the f a i l u r e planes. slope at 44*. A s t a b i l i t y a n a l y s i s on t h i s wedge i n d i c a t e s t h a t i t i s m a r g i n a l l y s t a b l e when dry, F.O.S.=1.07 (again assuming /=31* e 146 Figure 9.12 DESIGN SECTOR S-IO 147 10.0 MONITORING Monitoring of p i t w a l l s can be subdivided i n t o three p r i n c i p a l l e v e l s : 1) d e t e c t i o n of i n s t a b i l i t y , 2) determination of mechanics, and 3) mine and monitor. M o n i t o r i n g techniques, equipment and personnel requirements vary c o n s i d e r a b l y from l e v e l t o l e v e l ; t h e r e f o r e , each i s discussed s e p a r a t e l y below. 10.1 LEVEL 1 MONITORING The goal of L e v e l 1 monitoring i s t o detect a major p i t w a l l f a i l u r e very soon a f t e r movement commences. This i s most important f o r s a f e t y reasons as workers must not be exposed below an a c t i v e f a i l u r e unless i t i s being c a r e f u l l y monitored. A l s o , shear s t r e n g t h on the f a i l u r e s u rface decreases w i t h movement (from peak t o r e s i d u a l ) . When s t a b i l i z a t i o n i s r e q u i r e d , any s t a b i l i z i n g measures should be undertaken as soon a f t e r movement s t a r t s as p o s s i b l e . Any l o s s i n shear s t r e n g t h due t o movement must be replaced by a d d i t i o n a l a r t i f i c i a l support, u n n e c e s s e s a r i l y i n c r e a s i n g the cost of the s t a b i l i z i n g measures. The most p r a c t i c a l method of d e t e c t i n g i n s t a b i l i t y i s observation of the w a l l s f o r t e n s i o n c r a c k s . Cracks w i l l always appear long before the a c t u a l s l i d e occurs i f i t i s l a r g e , unless the s l i d e i s t r i g g e r e d by a l a r g e s e i s m i c event, e.g. an earthquake or a l a r g e non-delayed production b l a s t . To i n c r e a s e the odds of d e t e c t i n g a f a i l u r e a l l mine department s t a f f should be i n s t r u c t e d about the importance of r e p o r t i n g any observed crack t o the p i t s h i f t e r and s t a b i l i t y engineer immediately! 148 Some areas of the pit may not be accessed for long periods of time during operations, especially the upper slopes of the pit when mining progresses to greater depth. In order to detect any failures in these areas a regular inspection should be carried out by the s t a b i l i t y engineer, especially along a l l infrequently travelled pit benches, and on the p i t crest. During the inspection, he should be looking for cracks, evidence of increased ravelling, abnormal seepage out of the walls, and leakage from surface diversion ditches. The inspection should be carried out weekly during the spring run-off and times of abnormally heavy r a i n f a l l . During more favourable climatic conditions the inspection can be carried out on a monthly basis. Level 1 EDM (electronic distance measuring) is being used in several larger mines in British Columbia. Prisms are placed around the pit crest and along a bench mid-slope and monitored on a daily basis from permanent monitoring installations. This approach is very effective but requires a f u l l time s t a b i l i t y technician to carry out the surveys. A Level 1 EDM program proved practical in the Southern T a i l p i t and i t is recommended that the same procedures be used in the Main Zone. These include monitoring of strategically placed prisms on a twice weekly basis. Groundwater pressures should also be monitored as part of Level 1 s t a b i l i t y monitoring to establish the magnitude of destabilizing pressures and to evaluate the effectiveness of any dewatering programs. A l l accessible piezometers should be monitored on a weekly basis during the spring run-off period when piezometric heads w i l l be greatest. During the summer and f a l l months of 1985 the piezometers 149 should be monitored on a monthly b a s i s t o v e r i f y the seasonal trends observed i n the l i m i t e d 1984 piezometer monitoring program. During the w i n t e r , most piezometers w i l l not be a c c e s s i b l e so only one piezometer should be measured t o gain at l e a s t some informa t i o n about p i e z o m e t r i c response i n t h a t season. S i x a d d i t i o n a l piezometers should be i n s t a l l e d on 1280 bench of the Main Zone u l t i m a t e p i t t o determine pore pressures i n the w a l l near the bottom of the p i t . The piezometers should l i e i n v e r t i c a l s e c t i o n below e x i s t i n g piezometers on slopes above. 10.2 LEVEL 2 MONITORING The o b j e c t i v e s of L e v e l 2 monitoring are 1) t o determine the s i z e of the s l i d e , 2) t o e s t a b l i s h the f a i l u r e mode and l o c a t i o n of f a i l u r e surfaces,'3) t o o b t a i n approximate magnitudes of groundwater pressures a c t i n g on the f a i l u r e s u r f a c e s , and 4) t o determine the r a t e of movement of the s l i d e . At completion of the L e v e l 2 program there should be adequate i n f o r m a t i o n a v a i l a b l e t o make a d e c i s i o n on whether a mine and monitor program can be c a r r i e d out below the f a i l u r e or whether the area should be c l o s e d u n t i l the s l i d e comes down. I f i n a c r i t i c a l area, e.g. above the main haul road, the L e v e l 2 monitoring should provide s u f f i c i e n t data f o r the design of a s t a b i l i z a t i o n program. The complete monitoring program should be completed i n one week. Access t o the s l i d e area should be r e s t r i c t e d t o engineering s t a f f c a r r y i n g out the study u n t i l i t i s determined that there i s no immediate danger of c o l l a p s e . S t a b i l i z a t i o n should commence as soon as t h i s assessment i s made i f the f a i l u r e i s i n a c r i t i c a l area. 150 L e v e l 2 monitoring should begin immediately a f t e r a major crack observation i s reported. The s t a b i l i t y engineer and mine g e o l o g i s t should examine the area l o o k i n g f o r a d d i t i o n a l c r a c k s , evidence of groundwater seepage, and any g e o l o g i c evidence t h a t w i l l i n d i c a t e what g e o l o g i c s t r u c t u r e s are c o n t r o l l i n g the f a i l u r e . A l l observations should be recorded. A simple displacement monitoring s t a t i o n should be set up at the uppermost t e n s i o n crack. The r e q u i r e d apparatus i s i l l u s t r a t e d i n Figure 10.1. Readings should be taken every 12 hours or l e s s i f the r a t e of movement exceeds 1 cm/day. I f i t i s l e s s than 1 cm/day d a i l y readings w i l l p rovide s u f f i c i e n t i n f o r m a t i o n . The r e s u l t s should be p l o t t e d on d a i l y displacement vs. time and cummulative displacement vs. Figure 10.1 TENSION CRACK DISPLACEMENT MONITORING TOOL 151 time graphs a f t e r every reading. R e s u l t s should be i n t e r p r e t e d by the s t a b i l i t y engineer on a d a i l y b a s i s . An EDM monitoring program should a l s o be s t a r t e d . The program w i l l c o n s i s t of an adequate number of prisms l o c a t e d at regu l a r spacings along the center l i n e of the f a i l u r e . One of the prisms should be lo c a t e d w e l l above the t e n s i o n crack where no movement i s expected. The displacement monitoring g u i d e l i n e s should a l s o be f o l l o w e d i n de c i d i n g how o f t e n EDM readings should be taken. R e s u l t s should again be p l o t t e d and evaluated as soon as they are taken. Piezometers i n the v i c i n i t y of the f a i l u r e should be read t o e s t a b l i s h the magnitude of water pressures a c t i n g on the f a i l u r e s u r f a c e . I f e x i s t i n g piezometers are not i d e a l l y s i t u a t e d , one or two holes should be d r i l l e d along the c e n t e r l i n e of the s l i d e i f p o s s i b l e . The holes should be d r i l l e d s u f f i c i e n t l y deep t o penetrate 5m below the expected l o c a t i o n of the f a i l u r e s u r f a c e . Sonde soundings should be taken i n the holes t o e s t a b l i s h the exact p o s i t i o n of the f a i l u r e plane. A sonde i s a s t i f f s t e e l rod at l e a s t 2 m i n length that i s lowered down the bore ho l e . I t w i l l jam when s u f f i c i e n t o f f s e t has occured t o prevent i t from going down or coming back up the hole . The piezometer can be used as a sonde c a s i n g , w i t h the understanding t h a t water l e v e l readings may be a f f e c t e d s l i g h t l y by the sonde. At the completion of the Lev e l 2 monitoring program the s t a b i l i t y engineer w i l l be able t o advise management on the s i z e of the s l i d e , whether a mine and monitor program can be s a f e l y completed, i f s t a b i l i z a t i o n i s p o s s i b l e ; and what i s the recommended s t a b i l i z a t i o n 152 method. A safe, cost efficient mining program can then be developed by the mine engineering department. Figure 10.2 is a cross section through a slide that illustrates each component of the Level 2 monitoring program. 10.3 LEVEL 3 MONITORING Mining can be carried out safely under a f a i l i n g rock slope to within several days of failure provided a number of precautions are taken. These precautions form the Level 3 monitoring program. Called "Mine & Monitor", Level 3 monitoring provides detailed information on the rates of movement in the f a i l i n g rockmass. Level 3 monitoring requires precise instrumentation that may include several of the following: 1) pulley monitoring system with limit switches, 2) EDM, 3) potentiometers, 4) inclonometers, 5) shear strips, and 6) telemmetry. A large slide w i l l give warning before actual failure occurs. The objective of Level 3 monitoring is to detect the warning signal and 153 sound the alarm w e l l before f a i l u r e occurs. The warning comes as a gradual i n c r e a s e i n the r a t e of movement of the unstable rockmass. To detect the a c c e l e r a t i o n displacement readings must be taken and evaluated on a d a i l y b a s i s . The readings should be p l o t t e d on a d a i l y displacement vs. time graph and on a cummulative displacement vs. time graph ( f i g u r e s 10.3 & 10.4). I f the slopes of the two graphs become steeper the unstable rockmass i s a c c e l e r a t i n g ; becoming more unstable and approaching c l o s e r t o f a i l u r e . " I t i s g i v i n g the ALARM". June July Aug S«pt Oct Nov ' Dtc ' J a n Fob Juno July Aug Sopt Oct, Nov Doe Jan F o b I f the r a t e of movement exceeds 7.5 cm per day the s l i d e path and runout zone should be c l e a r e d of a l l workers and access t o the area i s t o be forbidden u n t i l f a i l u r e occurs or the r a t e of movement again drops w e l l below the c r i t i c a l l e v e l . I t i s very important t o r e a l i z e t h a t the above r u l e only a p p l i e s t o s l i d e s exceeding 100,000 u? i n volume. Smaller s l i d e s can occur very r a p i d l y and w i t h l i t t l e warning. Because the p r i n c i p a l aim of L e v e l 3 monitoring i s t o p r o t e c t the equipment operators and support s t a f f working below the s l i d e i t i s important t h a t a l l p i t workers have a good understanding of how the 154 monitoring systems work, what type of alarm i s g i v e n , and what t o do i f the alarm i s sounded. Employees working i n the p i t should be i n v o l v e d i n the mine and monitor program from the very s t a r t and kept f u l l y informed on d a i l y monitoring r e s u l t s and changes t o the systems. To create a f e e l i n g of t r u s t most of the instrumentation should be kept simple and a l l readings from s o p h i s t i c a t e d i nstrumentation should be i n t e r p r e t e d and p l o t t e d on a simple displacement vs. time graph. The p u l l e y monitoring system should be used as the primary method of L e v e l 3 monitoring because i t i s simple, e f f e c t i v e , and can be used and observed by the p i t employees. The system c o n s i s t s of a s t e e l wire t h a t leads from a sound anchor i n the unstable rockmass over one or more p u l l e y s t o a l i m i t s w i t ch anchored i n s t a b l e rock. The wire i s kept taught with a counter weight. I f movement occurs the weight i s p u l l e d upward. The l i m i t s w i t ch i s c l o s e d once displacement exceeds a predetermined magnitude, e.g. 1.0 cm per 8 hour s h i f t . The l i m i t s w i t ch should a c t i v a t e some form of alarm, p r e f e r a b l y a f l a s h i n g l i g h t and a s i r e n . The l i m i t s w i t c h should be reset at the s t a r t of every s h i f t and a p o i n t e r should be v i s i b l e on the mechanism t o i n d i c a t e the amount of displacement t o any i n t e r e s t e d employee. EDM monitoring of the hubs e s t a b l i s h e d during L e v e l 2 should be continued on a d a i l y b a s i s . The displacements must be evaluated and p l o t t e d the same day as the readings are taken f o r the program t o be e f f e c t i v e . I f more than one area of the p i t becomes unstable at one time then monitoring w i l l become a major task and may r e q u i r e the appointment of a f u l l time s t a b i l i t y t e c h n i c i a n . A l t e r n a t e l y , a computerized data a c q u i s i t i o n system can be added t o the AGA Geodimeter 155 so readings can be s t o r e d e l e c t r o n i c a l l y and then downloaded t o the computer. Software can be developed by the mine engineering department t o a u t o m a t i c a l l y reduce the data and c a l c u l a t e the displacement of each t a r g e t , update the displacement graphs, and give warning of excessive movement. Again, the data must be analyzed and p l o t t e d on the day i t i s taken. More s o p h i s t i c a t e d monitoring systems that u t i l i z e r o t a t i n g potentiometers, inclonometers, telemmetry, and computerized data r e d u c t i o n have been developed by s e v e r a l mines. Such systems r e q u i r e a h i g h l y s p e c i a l i z e d workforce during development of the system, and o f t e n d uring maintenance. Because Equity S i l v e r i s i n a remote l o c a t i o n and i n an area of severe c l i m a t e i t i s recommended that a s o p h i s t i c a t e d e l e c t r o n i c monitoring system not be used at present. Recent advances i n microprocessor technology may make such a system more r e l i a b l e and a f f o r d a b l e i n the near f u t u r e i n which case i t should be evaluated. A remote monitoring - telemmetry system was used t o monitor s l i d e s at Brenda Mines L t d . The system i s discussed i n d e t a i l by B l a c k w e l l e t . a l . , 1984. One of the best examples of mine and monitor technique occured i n 1969 at Chuquicamata Copper Mine, C h i l e (Kennedy, 1969). I t became evident i n l a t e 1968 that a major slope f a i l u r e was developing that would take out the only haulage r a i l w a y out of the p i t . Ore was s t o c k p i l e d and work began on r e r o u t i n g of the r a i l w a y . Displacement measurements i n d i c a t e d that the r a t e of movement was i n c r e a s i n g (see F i g s . 10.3 & 10.4). On January 13, 1969 a f a i l u r e date of February 18 was p r e d i c t e d . Subsequent monitoring i n d i c a t e d that r a t e s of movement 156 continued to increase and a decision was made to shut down the pit on February 17 as failure appeared imminent. The failure occured only hours later. In a l l the mine was shut down for only 65 hours. Such precision cannot be expected in most cases but work can continue safely under an active slide for a considerable period of time provided adequate Level 3 monitoring is also performed. A more local example of the mine and monitor technique as applied at Steep Rock Mines Ltd. in Ontario is described by Brawner et. a l . (1975). A large toppling failure was discovered above an active mining area. Because valuable ore was located below the unstable mass the mine and monitor technique was applied in an attempt to safely recover the ore before the failure occured. Instrumentation that was used included triangulation, EDM, wire extensometers with limit switches, crack separation callipers and a seismic unit. The EDM and wire extensometers proved to be the most effective instrumentation. The seismic unit did not work because of background noise due to mining activity. However, the most important lesson from this example i s not about instrumentation. The paper describes in detail how the mine staff and the Ontario Department of Mines were kept informed and involved in the mine and monitor program. A union member maintained a lookout near the failure on a 24 hour basis. His responsibility was to detect any ravelling or other sign of impending failure. A movement chart was was kept in the mine dry and updated on a daily basis to keep a l l staff well informed on the status of s t a b i l i t y of the slide. As a result of the excellent cooperation between the consultant, the mine and the mines' inspector the mine and monitor program at Steep Rock proved very successful. 157 11.0 CONTINUING PROGRAM The g e o t e c h n i c a l i n v e s t i g a t i o n i n t o improving p i t w a l l s t a b i l i t y i n the Main zone must not end with the completion of t h i s r e p o r t . So f a r the i n v e s t i g a t i o n has examined each of the f i v e g e o t e c h n i c a l c a t e g o r i e s that have the gr e a t e s t impact on s t a b i l i t y and s a f e t y i n the p i t . The c a t e g o r i e s are: 1) i n f l u e n c e of d i s c o n t i n u i t i e s , 2) groundwater, 3) shear strength parameters,.4) t r i m b l a s t i n g , and 5) monitoring. The sub j e c t s that have the gr e a t e s t p o t e n t i a l f o r improving s t a b i l i t y were examined i n great d e t a i l w h i l e others were reviewed only b r i e f l y because of time c o n s t r a i n t s imposed on the research. Valuable work remains t o be done i n each of the c a t e g o r i e s . An attempt was made t o provide g u i d e l i n e s i n each of the report s e c t i o n s as t o the d i r e c t i o n that f u r t h e r i n v e s t i g a t i o n should f o l l o w . This s e c t i o n i s a summary of those g u i d e l i n e s and b r i e f l y o u t l i n e s the goals that the p a r t i c u l a r research should achieve. The s e c t i o n s are reviewed i n the same numerical order l i s t e d above. 11.1 DISCONTINUITIES The s i n g l e most important t o p i c that must be i n v e s t i g a t e d i n the co n t i n u i n g program i s the d e f i n i t i o n of ge o l o g i c s t r u c t u r e along the west w a l l of the u l t i m a t e p i t . So f a r , the p i t design has been based on data c o l l e c t e d along exposures of the ea s t , and t o a l e s s e r extent, north and south w a l l s . Very l i t t l e of the west w a l l was exposed i n 1984 so the design i s based on the assumption t h a t the same s t r u c t u r a l trends observed elsewhere i n the p i t continue i n th a t area. Although there i s g e o l o g i c evidence t o suggest that t h i s i s l i k e l y i t i s very important t h a t a l l exposures on the west w a l l be mapped and the 158 structural data evaluated to confirm that the trends do continue. Structural mapping should also continue on a l l other benches in the Main Zone. The program does not have to be as detailed as the line mapping carried out during 1984. Mapping should only be carried out on every second pit berm (i.e. every 40 m). Because the major failures that w i l l influence p i t s t a b i l i t y are going to be controlled by "major discontinuities" collection of structural data should focus on faults, shears, dykes and joints exceeding 6 m in length. 11.2 GROUNDWATER The investigation into groundwater conditions in the Main Zone has indicated that i t should be possible to dewater the p i t , thereby achieving improved slope s t a b i l i t y and reduced operating costs, especially costs of blasting and equipment maintenance. Several dewatering systems were reviewed in the groundwater hydrology report and the most promising drainage system was identified. The WIP/GraD or alternate drainage system w i l l have to be optimized to get maximum drawdown at minimum cost. This program w i l l require detailed f i e l d observation of the influence of well spacing, pumping rate and well location in relation to geologic structure on the rate of drawdown. Piezometer installation and weekly monitoring w i l l form a major component of the study. Pump tests should also be carried out in the f i r s t few wells to better define the hydrologic variables: transmissivity, specific storage, and aquifer geometry. 11.3 SHEAR STRENGTH PARAMETERS Very l i t t l e work has been carried out in the study of shear parameters in the Main Zone with the exception of a detailed point 159 load t e s t i n g program. The i n i t i a l s t u d i e s i n d i c a t e t h a t f r i c t i o n angle i s i n the range of 30 t o 35 degrees and a small amount of cohesion i s present under low s t r e s s c o n d i t i o n s . By f u r t h e r i n v e s t i g a t i o n i n t o shear s t r e n g t h i t may be p o s s i b l e t o narrow the range of observed va l u e s , and more i m p o r t a n t l y , place greater confidence i n the r e s u l t s . Once the shear s t r e n g t h parameters are w e l l d e f i n e d i t w i l l be p o s s i b l e t o do a s t a b i l i t y a n a l y s i s on the p o t e n t i a l f a i l u r e modes i n each design s e c t o r . At present, the east w a l l of the u l t i m a t e p i t i s designed t o minimize the number of k i n e m a t i c a l l y p o s s i b l e f a i l u r e modes from d a y l i g h t i n g . I f the shear s t u d i e s and subsequent analyses i n d i c a t e that many of these wedges are s t a b l e then there may be l i m i t e d p o t e n t i a l f o r steepening. The p o t e n t i a l i s l i m i t e d because berm s c a l e f a i l u r e s are p r e s e n t l y being observed and f u r t h e r steepening would r e s u l t i n a d d i t i o n a l f a i l u r e s w i t h greater volume. As a r e s u l t , the catchment c a p a c i t y of the berms would soon be exceeded because l a r g e r volumes of d e b r i s would have t o be s t o r e d i n a smaller area. The r e d u c t i o n i n storage area i s due t o the f a c t t h a t p a r t s of the lower berm would a l s o f a i l . I t i s important t o know the magnitude of shear s t r e n g t h that w i l l develop on the f a i l u r e planes when a s l i d e has to be s t a b i l i z e d . The q u a n t i t y of support r e q u i r e d must exceed the d i f f e r e n c e between the d r i v i n g f o r c e s of g r a v i t y and water pressure and the s t a b i l i z i n g f o r c e of shear str e n g t h on the f a i l u r e planes. The support requirement can be estimated a c c u r a t e l y only i f shear s t r e n g t h i s known. Otherwise the support system must be based on worst case assumptions and w i l l l i k e l y be overdesigned and u n n e c e s s a r i l y expensive. 160 11.4 TRIM BLASTING Considerable work has been done t o date on refinement of the t r i m b l a s t p a t t e r n t o reduce the amount of b l a s t induced damage to the rockmass i n the f i n a l w a l l ; however, f u r t h e r refinement i s p o s s i b l e . I t i s recommended th a t a w e l l organized t r i a l program be i n i t i a t e d t o t o determine whether changes t o the t r i m b l a s t suggested i n s e c t i o n 8.4 do indeed improve the c o n d i t i o n of the f i n a l w a l l . The program would c o n s i s t of systematic changes t o the t r i m b l a s t p a t t e r n and c a r e f u l docummentation of the r e s u l t s . The present c o n d i t i o n of the w a l l s would have t o be evaluated f i r s t t o serve as a reference. S t i l l photography would be used e x t e n s i v e l y t o record the c o n d i t i o n of the f i n a l w a l l . High speed photography would be a p p l i e d t o study the mechanics of the b l a s t and t o evaluate behaviour of the muck p i l e . The researcher would have t o work c l o s e l y w i t h the b l a s t i n g crew t o gather a l l neccessary i n f o r m a t i o n and ensure t h a t each t r i m b l a s t i s d r i l l e d and loaded according t o design. The goal of t h i s program i s to reduce b l a s t damage t o the v o l c a n i c rockmass so i t w i l l remain i n t a c t and maintain steeper berm face angles. I f berm face angle can be inceased from the c u r r e n t 66*to 70* there i s e x c e l l e n t p o t e n t i a l f o r a d d i t i o n a l p i t steepening i n areas where the p i t w a l l angle i s c o n t r o l l e d by s t a b i l i t y of the i n d i v i d u a l berms. The p o s s i b i l i t y a l s o e x i s t s t h a t many of the berm s c a l e wedge f a i l u r e s along the east w a l l berms i n gabbro have been t r i g g e r e d by expansion of b l a s t gases i n t o the c r a c k s . P r e - s p l i t b l a s t i n g may reduce t h i s damage, c r e a t i n g a cleaner and more s t a b l e u l t i m a t e w a l l . 161 11.5 MONITORING Le v e l 1 monitoring w i l l be an ongoing part of the c o n t i n u i n g g e o t e c h n i c a l program. I n i t i a l l y , a l l p i t personnel must be educated t o keep an eye out f o r sign s of i n s t a b i l i t y and t o report any observations. The monthly s t a b i l i t y i n s p e c t i o n and report procedures should be c a r e f u l l y organized so that they w i l l r e q u i r e the very minimum amount of time to complete. L e v e l 2 monitoring w i l l only be r e q u i r e d when a f a i l u r e occurs; however, response must be f a s t when i t does occur so the s t a b i l i t y engineer and surveyors should develop a set of g u i d e l i n e s t h a t they w i l l f o l l o w and a l l necessary equipment should be a v a i l a b l e f o r use on s i t e . „ Lev e l 3 monitoring w i l l begin s e v e r a l weeks a f t e r the f a i l u r e i s f i r s t reported so there w i l l be adequate lead up time t o i t . I t i s t h e r e f o r e not p r a c t i c a l t o make ext e n s i v e preparations f o r a Level 3 monitoring program because such a program i s very s i t e and f a i l u r e type dependent. The monitoring procedure should be reviewed by the s t a b i l i t y engineer and surveyors so th a t they are aware of the type and q u a n t i t y of work that such a program w i l l r e q u i r e . 162 12.0 CONCLUSION The slope s t a b i l i t y study of the Main Zone has established that steepening of the p i t by as much as 5° should be possible i n the west north, and south walls. Numerous unfavourably oriented d i s c o n t i n u i t i e s occur i n the east wall; i t i s therefore recommended that i t remain at 45* . The p i t wall design program i s based on an analysis of s t r u c t u r a l geology, shear strength of d i s c o n t i n u i t i e s , and groundwater conditions i n the Main Zone. A l l a c cessible benches i n the Main Zone were l i n e mapped i n d e t a i l to c o l l e c t s u f f i c i e n t information on the o r i e n t a t i o n s of d i s c o n t i n u i t i e s that w i l l c o n t r o l f a i l u r e . Based on the data c o l l e c t e d the Main Zone was divided i n t o four s t r u c t u r a l domains, each domain having consistent rock type and consistent trends i n the o r i e n t a t i o n of d i s c o n t i n u i t i e s . Because l i m i t e d exposures existed on the west wall of the p i t at the time of mapping design work i n Domain 3 was based primarly on s t r u c t u r a l trends observed i n adjacent domains. As a r e s u l t , the s t r u c t u r a l trends used to determine the optimum p i t wall angles are not s u f f i c i e n t l y r e l i a b l e t o be used for a f i n a l design of the west wall. They do i n d i c a t e that the geologic structure w i l l be favourable, as does the regional s t r u c t u r a l geology; however, the s t r u c t u r a l trends and p i t wall designs must be v e r i f i e d by further l i n e mapping and a n a l y s i s once a d d i t i o n a l exposures are uncovered i n the west h a l f of the i n t e r i o r p i t . Only then can there be a commitment to the f i n a l ultimate p i t wall angle i n the west w a l l . 163 The Main Zone p i t has been d i v i d e d i n t o 10 design s e c t o r s . The p o t e n t i a l f o r f u l l w a l l , berm s c a l e , and step f a i l u r e was c a r e f u l l y analyzed i n each s e c t o r . O v e r a l l and berm face angles were s e l e c t e d t o minimize the p o s s i b i l i t y of developing l a r g e areas of i n s t a b i l i t y i n the p i t . However, as some c o n t r o l l e d f a i l u r e s can be t o l e r a t e d the p i t w a l l angles were not designed t o e l i m i n a t e the p o s s i b i l i t y of a f a i l u r e . Rather, a l l f a i l u r e modes that appeared t o have p o t e n t i a l f o r causing s t a b i l i t y problems were evaluated t o determine the f a c t o r of s a f e t y and the p r o b a b i l i t y of the two planes a c t u a l l y i n t e r s e c t i n g i n the sector t o form a wedge. The p i t w a l l angle was reduced t o prevent a p a r t i c u l a r f a i l u r e mode from d a y l i g h t i n g only i f the analyses i n d i c a t e d t h a t the wedge was unstable and a l a r g e number of the c o n t r o l l i n g d i s c o n t i n u i t i e s were observed i n the design s e c t o r . By adopting t h i s design approach the p i t w a l l s w i l l not be u n n e c e s s a r i l y overdesigned while maintaining a s u f f i c i e n t l y high degree of s t a b i l i t y . Groundwater reduces s t a b i l i t y of the p i t w a l l s , presence of water i n the p i t a l s o increases operating c o s t s of b l a s t i n g and equipment maintenance. To improve groundwater c o n d i t i o n s and reduce the chance of f a i l u r e s i n the p i t i t i s recommended that an aggressive dewatering program be immplemented i n the Main zone. A d e t a i l e d study of p i t dewatering was c a r r i e d out as p a r t of t h i s g e o t e c h n i c a l i n v e s t i g a t i o n . R e s u l t s i n d i c a t e that some form of i n - p i t w e l l system w i l l be r e q u i r e d t o dewater the rockmass because of i t s r e l a t i v e l y low p e r m e a b i l i t y . In theory, the WIP/GraD drainage system that c o n s i s t s of f r e e f l o w i n g g r a v i t y w e l l s i n the p i t w a l l s and pumping w e l l s on the p i t f l o o r appears t o be the t e c h n i c a l l y optimum dewatering method f o r the Main Zone p i t . However, a d e t a i l e d e v a l u a t i o n and t e s t i n g program w i l l be 164 required before a f i n a l decision is made on selecting the most practical drainage method. The s t a b i l i t y of most slope failures is very sensitive to the magnitude of shear strength developed on the failure surfaces. In order to carry out the s t a b i l i t y analyses for pit design, reasonable values of f r i c t i o n angle and cohesion were required. A study was undertaken in the summer of 1984 to establish these parameters. The study consisted of point load tests, inclined s l i p tests, and back analyses of berm failures. The test results indicate that c=10.5 kPa, 0=31* appear to be reasonable estimates of shear strength. A more detailed shear strength study should be undertaken to better define these important parameters. Blast damage to the rockmass behind the ultimate wall can result in a much less stable pit because numerous cracks are opened up, the rockmass looses i t s intactness, and shear strength on existing discontinuities can drop from peak to residual levels. To reduce blast damage a good trim blasting program has been developed at Equity. A study of existing literature suggests that there is further potential for reducing blast damage. Key changes that deserve additional study •include: 1) use of ANFO in line holes, 2) reduction of charge per hole, 3) reduction of burden, 4) changing trim pattern to match rock conditions, 5) inclusion of the Hercudet intiation system, and 6) changing the f i r i n g order. 165 As some sm a l l f a i l u r e s of the p i t w a l l are a n t i c i p a t e d an e f f i c i e n t monitoring program must be developed so the f a i l u r e s w i l l be detected q u i c k l y and w i l l not endanger regular operations i n the p i t , e s p e c i a l l y the w e l l f a r e of the workers. The monitoring program s h a l l c o n s i s t s of three l e v e l s . L e v e l 1 i s designed t o detect any i n s t a b i l i t y i n the p i t . L e v e l 2 w i l l determine the nature of the f a i l u r e and the degree of hazard t h a t the f a i l u r e presents. L e v e l 3, or "mine and monitor" w i l l a l l o w safe operation under an a c t i v e unstable slope. S u b s t a n t i a l work remains t o be done i n the g e o t e c h n i c a l i n v e s t i g a t i o n of slope s t a b i l i t y i n the near f u t u r e , e s p e c i a l l y i n the areas of p i t dewatering, s t r u c t u r a l design of the west w a l l , and improvements t o the c o n t r o l b l a s t i n g program. I t has been the purpose of t h i s report t o provide some guidance as t o the d i r e c t i o n s that the ge o t e c h n i c a l work should f o l l o w i n order t o o b t a i n maximum improvement of p i t w a l l s t a b i l i t y . 166 13.0 BIBLIOGRAPHY Beaudoin, P. INTERNAL REPORT ON DEWATERING OF SOUTHERN TAIL PIT; Equity S i l v e r Mines L t d . Houston, B.C. 1981. Brawner, CO., Stacey, P.F. and Stark, R. A SUCCESSFUL APPLICATION OF MINING WITH PITWALL MOVEMENT; Proc. Annual Western Meeting, Canadian I n s t i t u t e of Mining, Edmonton, A l b e r t a , 1975. Buckley, P. and M i l l e r , J . PRELIMINARY REPORT - MAIN ZONE ULTIMATE PIT SLOPE STABILITY; I n t e r n a l Report, Equity S i l v e r Mines L t d . , Houston, B.C., 1983. Carpenter, T.L. and Young, R. DEEP WELL DEWATERING AT GIBRALTAR MINES; CIM B u l l e t i n , 1980. Freeze, R.A. and Cherry, J.A. GROUNDWATER; Englewood C l i f f s , N.J. P r e n t i c e H a l l Inc., 1979. Herget, G. PIT SLOPE MANUAL CHAPTER 2 - STRUCTURAL GEOLOGY; CANMET report 77-41, 1977. Hoek, E. and Bray, J.W. ROCK SLOPE ENGINEERING; London, England. I n s t i t u t i o n of Mining and M e t a l l u r g y , 1981. HYDROLOGICAL INVESTIGATION - EQUITY SILVER MINES' PROPERTY; I n t e r n a l Report by Gol d e r ' A s s o c i a t e s , Vancouver, 1983. Kennedy, B.A., Niermeyer, K.E. and Fahm, B.A. A MAJOR SLOPE FAILURE AT THE CHUQUICAMATA MINE, CHILE. Mining Engineering. A.I.M.E., V o l . 12, No. 12, 1969, page 60. Pease, R.B. (Ed.) GEOLOGY AND MINERALIZATION AT EQUITY SILVER MINES LIMITED; i n t e r n a l r e p o r t , E quity S i l v e r Mines L t d . , Houston, B.C. 1983. Sharp, J.C. et a l . PIT SLOPE MANUAL CHAPTER 4 - GROUNDWATER; CANMET report 77-13, 1977. V o l . 12, No. 12, 1969, page 60. S p e r l i n g , T. POINT LOAD TESTING PROGRAM - PROCEDURES AND RESULTS; I n t e r n a l Report, E q u i t y S i l v e r Mines L t d . , Houston, B.C., 1984. S p e r l i n g , T. and CO. Brawner, MAIN ZONE HYDROLOGY; I n t e r n a l Report, Equity S i l v e r Mines L t d , Houston, B.C., 1984. W e t h e r e l l , D. G. GEOLOGY AND ORE GENESIS OF THE SAM GOOSLY COPPER-SILVER-ANTIMONY DEPOSITS, BRITISH COLUMBIA; Unpublished M.Sc. t h e s i s , Department of Geology, U n i v e r s i t y of B r i t i s h Columbia, 1979. Wodjak, P.J. ALTERATION OF THE SAM GOOSLY COPPER-SILVER DEPOSITS, BRITISH COLUMBIA; Unpublished M.Sc. t h e s i s , Department of Geology, U n i v e r s i t y of B r i t i s h Columbia, 1974. 167 APPENDIX A A . l STEREONETS FOR DOMAIN Dl 168 D1 A 435 OeSERVAT I O M S W I T - 4 TC T A L T G H T O C C O U N T I N G C I R C L E I S 1 . X O F T O T A L A R E A i33.0 11 111 111 •1111 1 1211111 111111111 2122112211 22211221 . 223221111 322221111 222211111 22121 111 21111111 111 11 11 11 1 22344433445455533 11111234444555666 555554322221 1111 1? T344466666765644472211111111 11211111 1334444555544456533221 1 1221222 1111122121222233445445543432 22 222111 12222 2111 11 11222234444455544333333232111111111112222221 122222-44554555 33 532221211111111 11111 1211 122123 3743*4432211111 111111 1111 11111122 7.232221111 11 1 11 11111 1 1 1 111111 111 1 1111 1111 111111 11111 11111 111111 1 1 11 I 1 1 11 1 1 1 1 II 11 1 1 1 1 1111111 1111 • 1 11221111 1 1 1 22332 21 1 1112333233221 112J233332211 1222222221111 11 1 1121221 111112 1222111 11111 111 1 1111 11 1111 111111 1111111 1111111 11 1 1 1 1 1 111 1111111 2211111 12111111 2222221 23333321 1 111 11222 111112 11123 2222322111111233 2223222111 11222 123222311 11122 11222211 111112 1111111111 1 1122111111 11 122112111111 111 111111111111 11 1111111111111 1 11111111 11111111 11 11 1 11 11111 11111111111 11 1 1 1 1 1 1 2 22 21 1 1 1 1 1 1 1 1 1 1 1 1 222222352235222222111111 35343332322322211 111 111 1 11 11 11 1 111 11111 1111111 11111 11 169 D1 FU 2 J O B S E R V A T I O N S WITH T O T A L WEIGHT OF 27.1 C O U N T I N G C I R C L E I S 1.X OF T O T A L AREA 36AAA666 I I 3 6 6 A A A A A 6 6 6 6 4 I 3 3 31 33 3646 31 3 ! 3 3 3 < I 1 3 3 7 3 1 3 6 6 6 6 4 3 3 3 3 1 ! 7 3 6 6 6 5 7 3 3 I 3 3 3 S 3 3 6 3 3 1 3 3 3 3 I 3 1 3 1 3 1 3 1 1666AA6D66AAA633333333333333 3 3 3 3 3 3 3 1 3 3 6 A A A A A H 0 6 A A O O A 3 3 3 I 3333 3 3 3 3 3 3 3 7 6 A A 6 4 D D D A A A D D 6 6 3 3 6 6 6 6 3 6 0 A A O O A 6 4 3 3 3 3 33333 1 3 3 3 3 3 3 3 6 6 6 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 1 3 3 3 1 3 3 3333333 , 3 6 6 6 1 3 1 66633 3 3 3 I I 1 3 3 6 6 6 6 6 J 3 3 1 * 3 3 3 1 6 6 6 6 6 6 3 I 3 1 3 6 6 6 A O O A 6 6 3 3 3 6 0 0 H H D A 3 3 3 3 6 A A 0 0 6 6 3 3 4 A A A A 6 6 3 3 3 3 3 3 3 I 6 A 0 6 6 6 4 3337 3 3 3 3 3 3 3 6 6 6 6 3 3 3 3 3 3 3 3 3 3 1 3 3 3 1 3 3 3 3 3 3 3 3 1 3 3 3 3 3 5 3 • 3 33 3 1 53 3-3 1 3 3 3 1 I I 3 I 3 1 6 3 . 3 T 3 5 3 33 3 6 6 6 3 3 I 3 3 M 3 3 3 6 6 6 3 3 3 3 3 ^ 3 3 6 6 3 3 3 1 3 33T3 3 1 3 1 3 3 J 3 3 3 3 3 3 , 3 , 3333 313 33 33 3 3 7 13 1.1 3 3 3 3 3 7 3 I 3 3 1 1 3333 3 3 3 3 3 1 3 3 3 333 1 3 3 3 1 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 1 3 3 3 1 333 I I 3 6 6 6 6 6 6 3 3 6 6 6 4 6 4 3 3 3 7 3 6 6 6 6 6 6 A 6 6 6 3 3 3 170 01 cu 34 OBSERVATIONS WITH TOTAL WEIGHT OF COUNTING C I R C L E I S 1.Z OF TOTAL AREA 36.0 2222 22222 22222 22222 -22222 222 5 222 85822 BBS852 88885 388882 53852 5552 22255522225555 252222555355BB888555222 :2 222225589888585552 2222 2 2255583835588855525522222? 22? 2255S85885585222 22555222 22 2 22 72-» 2 22 22522255 5 5 522252 22 22222222222 22222 322555552225552222 2255555522 255555522 2272222 22222 25555 22222222 5555555 22222222 25555552 22555552 2555555 5555255222259852 222255552552222 2 222555225552222 255 22255352222 2225B 8888388522 22588 22222 2255885552522255558B 552222222258835525222785555 22555522252588885525222255555 2225555522 3 5 5 5 5 88522222222222 22225552 225255522 22222 222 22222 225555222 25552222 2222Z 22 222 55552 555555 2555555 255555 5555 22 2 2 1 22227 27222? 272 2222222 222222222 2 2222222222 22222222 222225555525552 2222555522 171 01 SR 19 OBSERVATIONS WITH ICTAL WEIGHT OF COUNTING CIRCLE IS 1.X OF TOTAL AREA 1 '.'3 555AAFFFFAA555AA5 55AAAAA5AAAAAAA555555 55555S5S5A555SAAAA55555 555555555 55555555 AA 555 55555555 5AAAAAA5 AAAAAAAA5 555555555 5AAAAAAAA 55555555 5555 5 5 555 5555555 5555555 5555555 55 555 555555555 555555 55555 55555 5555AA555555 555555 55555AAA5555A5 5555555 555555AA55AAA5! 555 5555555 5555555 5555* 555 55 55 5 5555" 555 5 555 AAA! U S 5555 5555 555 5555 5555' 5 555 5555 555' 555 5 555 55' 55 5 5 555555 5555555 5555555 555555 55 55 555 55 555 55 55555 555555S 5555555 555555 55 555 555555 5555555 5555555 55555S 55 5555 55555 555555AAAAAA55555 . "* I - " 172 0 1 J N 3 4 9 0 3 5 ; R V A T I O N S W! C O U N T I N G C I R C L E I S TH TOTAL WEIGHT 0= 1 . X OF T O T A L AREA 3 4 7 . 0 1 111 111 - 1 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1 2 2 2 2 1 1 2 2 2 1 1 2 2 2 2 1 2 2 2 22 21 21 2 1 1 1 1 1 1 11 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 11 111 11 t 1 11 1 1 1 111 11 2 1 1 21 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2 2 1 1 1 1 1 111 1 2 2 3 4 4 3 3 3 4 4 4 4 4 5 5 3 2 1 11 1 2 2 3 4 4 4 4 5 5 5 6 6 5 4 4 4 4 4 4 3 2 2 2 1 2 1 1 1 1 1 1 2 3 4 4 4 5 6 6 6 6 6 7 6 6 6 4 4 3 * 2 1 1 1 2 2 7 2 2 2 2 2 1 1 1 1 1 3 3 4 4 4 4 5 6 5 4 * 3 4 5 6 4 3 2 2 2 1 7 2 2 2 2 2 1 1 1 1 2 2 2 1 7 2 2 2 2 2 3 4 4 4 4 4 4 5 5 4 4 5 3 2 2 2 1 1 1 1 2 2 2 2 2 2 2 2 111 1 1 2 2 2 2 3 4 4 3 3 4 4 4 5 4 4 3 4 3 3 3 3 2 2 2 1 1 1 1 1 1 1 1 1 1 2 2 3 3 3 21 11 1 1 2 2 2 2 4 7 4 4 4 4 4 4 3 3 7 3 2 2 2 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 1 1 1 1 1 1 2 2 2 2 3 3 3 3 3 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 11 1 111 111 11 1 1 1 1 1 1 1 1 1 1 1 1 111 1 1 11 1 1 1 1 1 1 2 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 111 1 1 2 2 2 2 1 1 1 1 2 2 2 2 3 4 2 2 2 1 1 1 7 2 3 7 4 4 3 3 2 2 1 1 2 2 3 4 4 4 3 4 3 7 1 2 1 2 2 2 2 3 2 7 2 2 2 2 2 1 1 1 2 2 2 2 2 2 1 1 1 1 1 1 1 1 2 2 2 2 1 2 7 1 1 1 2 2 2 2 2 1 2 2 1 1 1 1 7 2 2 2 2 1 2 2 2 1 1 1 1 2 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 11 11 1 I 1 I 1 I I 1 1 1 1 1 1 11 11 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 11 1 1 1 1 111 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 2 2 1 1 1 1 1 1 2 1 1 1 2 2 2 2 1 1 1 1 1 1 1 1 2 1 1 1 2 1 2 2 2 1 2 1 1 1 1 2 3 2 1 1 1 2 2 2 2 1 1 1 1 1 2 2 2 1 2 2 2 2 2 2 1 1 1 1 2 2 1 1 1 1 2 1 2 1 1 1 1 1 2 1 1 1 1 1 2 2 1 12 1 1 1 2 2 2 1 1 1 1 1 2 1 1 1 1 1 2 2 2 2 1 1 1 1 2 1 1 -1 1 1 1 1 2 2 2 2 1 1 1 1 1 1 1 7 1 1 1 1 1 1 2 2 2 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 111 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 2 2 2 2 2 2 2 1 1 1 2 2 2 2 1 2 7 2 2 2 2 3 3 * 3 3 3 3 3 2 2 2 2 1 1 1 11 3 * 3 4 3 3 3 2 3 2 2 2 2 2 1 1 1 1 11 1 1 1 11 1 . 1 1 1 11 11 111 1 1 1 11 11 111 111 1 1 1 1 1 1 1 1 1 1 2 2 1 2 173 01 MJ 105 OBSERVATIONS HITl TCTAL WEIGHT OF 105.0 COUNTING CIRCLE 15 1.Z OF TOTAL AREA 2245543344J334544 3 3222345655 77554454 44 54374323 323521 1456 6668988553343321211211 44543221 3 3 5 577785422343211121 12234443322222347444434331 1111 1111 1112323534566422444344443327222211 11 11 1 1 1 1 1 1 2745556576434543533342222111211 111111 744424464*3432322122211 11 11111 13232211 11121 •1111 11-IIH 111 111 111 11 11 1 1 111 111 1 1 1 111 1111 1111 1 1 2 23 1 1 11111 11111 1223221 1222221 22221 1111 11 1 1 1 2 "211 2 33453321 3 445544 33 21 24465453722 22233333221 11 111111 1 1 1 11 1111 111 11 1111111 1111 1111111 11111111111111 1111111 111 111111 1 1111111 11 11 11 11 11 1 1211 !21 1 111 1 2 1 22 21 !1 11 1 23 23 !2 1 22 34 >1 1 112223 521 111233 521 1 113 121111 221 1 1121111 111 1 1111111 1 11 1 111 111 11111 171 111111 1 23322211 111 11 11 1212222332211 1 121123 11232234421132333322 1 11 111233 333434554466554344311 1 222 2.1 33 555755534 33333112 174 01X.S 34 O B S E R V A T I O N S WITH T O T A L WEIGMT OF C O U N T I N G C I R C L E !S 1 . JC OF T O T A L A3EA 34. 27244544447777443 1 21 11 1 232544585 7878 877537 3331 111 122223347775454775333321 1 11111 27444545535777544245 373111 111 1 127221 11 1 233445435423554443443322221 1 1111 1 122232755577354447337233433322322222221 11111 23 1337 77 58399844232211 33221 1 1 1 1 1 1 1 11 1 1 2712255877788441 222212757887431111 11111 2223 3731111 111111 1 1 2111 22111 21111 11111 •111221 1122111 1 1111121 2 11122211 222222211 4342321 11 544322111 54 3321 11 544231 343 21 2221 1 111 111 111 11 1 11 11 11 1 111111 : 22222 12222 111132222222 23333 11112211133322222 133*3 1111122211134433331 2333 11111122112224555233113455 1111111 1112333333324434 1111333433224443 222232123345874 1111111 4458399 1222221213357577 2322222211357755 112233221213458944 1112222211 33433754 11112221 133434331 11111 113344431 111344411 111112111 11 11 1 11 1 1 1111 1111111 1111111 1 1 2221 1 1' 11122221 1111111 111111 1 1 21 2 233 1 2235 1 2345 1 1 223345 11133444 11123334 111222222 111112221 11111 1111-1 1111112 22232112 22223311 1 2272 33 1 1 122223111 2222111 11111 11111 11122111111 12212222221 11222222111 11222222 1 11 1 1 1 1111111 11 1111111111 111 11111222232222122? 1111 11111 1111 111 1111 11111 111 1 11 111 111 1111 111 11111 11 11111 1 11 4 3 3 5223 3 3 3343 33 22 175 D 1 M A 1 8 ? O B S E R V A T I O N S W I T H T O T A L W E I G H T O F 1 8 7 . 0 C O U N T I N G C I R C L E I S 1 . X O F T O T A L A R E A A 2 23555444*55555*4 23222214555666556 466565 53 43 32 222211 12344446667664454543322321 1 2 237222 1 2 34566665534555433273 11 1 1 1 1 1 11 11123332322222344454444333322323322112711 1 11 11 22 34 544665456544444433333333222222127211 1 1 1234444666766664443333233221121111111111111 1 134374566555643211112111111111 11111 1 123323434444331111 11111 1 111 111 1111111 111111 11111111 11111 11 1.11 11111 11 11111111 12 12222221 1 1112313222112 111222222212 11111 11111 211111 222211 21 221 1 11222221112 2211 11 1 2 2 111121111122 332211 11 2 3 2223 444321 12 23 11111 t 2233 33322111 111 233 1211111111233 43323211 121 223 111 1122111112274 53323211 112 1 1 3 111 1111111 22222 43221211 111 111 111 111111 12223 53211111 11 111 1 1 1 1 1 111 1 1 111 1122 332221 1 2 1 1 1 1 1 1111 11 • 1 23 3223211 22111111 . 1111 11 1 2 2222211 1111121 111 12 21111 11 1222211 11 11111 12 222232211 1 112 1 111 1 221111 1 1222'2222211 11 111111 1111111 111 1 23121 1 112233232211 1111111 1111111 1111111 111 1 33 21 1 11122722111 1111 1111111 1111111 1 111111 111 33221 111 11 111111 11111111111111 111 11 11 33321 111 1111111 111 2 22111111111 1 111111 1111 111111 11 111 1 1122222 1111 1 1 2222 31 1 11 1 22221 1 1 111 111 111 1111111 ' 11111 11111111 11111111 1 1 111121 11122222111 112222222321111 1 11 1111111 1 12211111 11 111121122 1122323123211222222221111111111111222 227333442 744333 5333222222 2232 54454443453473222 J F I N 176 A.2 STEREONETS FOR DOMAIN D2 -.. J 2 4 OBSERVATIONS WITH TOTAL WEIGHT OF COUNTING CIRCLE IS 1.X OF TOTAL AREA 1490.7 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 1 1 1 1 1 1 1 1 2 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 11 1 1 1 1 1 11 11 11 21 1 I 11111 1111111 1111 111211 112111 11222222 11222321111211111 1 1 222321 1 1 1 1 1 1 11 I 12122221111 111 111121111 11 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 2 1 2 2 2 1 1 1 11 11111 2 111 1111 1 1111 J3 1111 111 1111 542 1 11 111 1 ~<-21 1 11 1 ,211 1111 1 331 11111 1 1 1 1 1 1 1 1 1 1 1 11 1111111 1 1111111111111 11 111122221111 1 1222222371111 11122233333322111 11122244654442211111 11455666665555311111 12345788778755321113 123468889AA976421125 274677BABBCB86331246 11245688AABBA97432J56 11112234579AAA987442335 111132 34 56678995544454 5 22131223443445443445444 33221212232311222344433 3322222223221 122345433 3322322222211 233434332 43221211122122223333321 21111111111222222211221 1111 1 111 22222222221 1 1111111221 1 1111 111 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 178 ! F L - 29 O B S E R V A T I O N S W I T H T O T A L W E I G H T O F C O U N T I N G C I R C L E I S 1 . X O F T O T A L A R E A 5 7 . 3 33 33 5 333333 3333323 333333 3333 BBBB995333311 5 7 8 9 9 9 B B B 0 7 7 7 5 5 1 1 3 3 3 3 3 3 5 6 3 5 5 5 5 7 7 5 3 3 3 1 1 1 3 3 3 3 3 3 3 5 5 2 2 3 3 5 5 5 3 3 3 1 1 1 1 * 3333323 2 2 2 2 2 2 1 1 1 1 1 1 3 3 2 444444 222222222 599BB96662 22222 222222222 5 5 9 9 B 3 B 3 9 6 2 2 2 2 2 2 2 2 2 2 2222222 2559BBBB9222 2 2 2 2 2 2 2 2 2 2 5 5 5 5 7 7 2 2 2 2 22222222 22 * * * * * 333333 4 * * * * * 8 3 3 3 3 3 3 * * * * * * 3 8 3 3 3 3 3 3 * * * * * * * 333 33 3 * * * * * 2 22222 22222* * *222 233222**2222 1133333222 111133333 11111111 111 55 555 444555 4774AA5 277777AA 2FFFF774 AAFFFF7* 7AAAFFA 77AAA77 77777 55 555 555 555 55 I I m n i I I I I I I I I I I I I I I I I I I I I m 2222 2212 11 1333333111 33777777535 11133579BDBB 4444 44444444 44*****4 4444444 444 3 179 •CM - 42 OBSERVATIONS WITH TOTAL WEIGHT OF 45.9 COUNTING CIRCLE IS 1.X OF TOTAL AREA CCBCBB97643111111 113699CEEEEEC7643133333331 1 1111344 89 3999 8664314 3 33 3336 5 5 351111 13335565866666113355555888866666111 11111133322222 155333556AA66646661111 111111111 1111155553355366666651 222445333311 1133333553331J3153331 222 24 4444 22 2 33333353311113311111 2 22444442 22 11111113 311113 3113 33311 2222442222 111111 1111311135553331 2222 1115533333 1 3333331 2255522222 22255552222 22225555222 22222522 1111111 11 333 3 3 333333 333333 3333333 3333335522333333 3338BB522263333 3HHHKK8B5556J3 8 EEHGRUMGG5 3 J 3EEEPRUHGG033 8EEPPSOD0033 8 8 J J A D O D 0 3 A AAA A 111 1 111133 111113 11111 11 1111 311111 31111 2222222 2222222222 2222222221111111 1 33 222 34433333331 11111 34688999C 180 v - 32 OBSERVATIONS WITH TOTAL WEIGHT OF COUNTING CIRCLE IS 1.X OF TOTAL AREA 64.5 444*33 64333 1344444333 26667764436644466664 22 2 22 466644 5566777763111 22222666 44445733466643313111 22 2244442111534444355311111 1133555511133111111 4444* 11111113311111111111 44444444 11111111 37AAAAA64 22411 3333000EEEA 22222222 3 33 3990HEH003 2 2 22 22 2 2 3333600000A775222222 3 3 3 3 3 A 7 A A M H * 3 3 2 2 2 2 441MMHII3 F F I U I F " F F F F F F F FFFFF 22222 222222 222222 22222 111111 111111111 1113333331 1333331111 11111111 111111 2 2 3333 333333 3333333 333333 73323 333 3333 333333 3333337 333333 3333 H H H H H H H H H H H H H H H H H H H H H H H H H H H H H 22222 22222222 22222222 2222222 2222 222 353333333 33 1135555553666433362 1333336666B664333 111333333313 181 •-.15 OBSERVATIONS WITH TOTAL WEIGHT OF 1497-6 COUNTING CIRCLE IS 1.X OF TOTAL AREA 1111 1 111111111111 111111111111111 111 11111111111111111 1 1111 11111111111111 11 1111111111111 1 1111 111111111 1 1 11111 111 11 1111 1 12211 2 121111 11 1 1 222222 111111 2 11 12 '22332111111111 1 11 11 < !22331 11 11 11 11 1 1 11 12 2222111111111 1 11J '222121 11 11111111 2 1 2112211 1 11111 ,4 111 11111 1111 643 1 1 1111 1111 •31 111 111 111 111 .211 111 111 111 43211 111 1 1 21 111 1 1 1 11 1 1 2 11 111111 111121 122223 12233332 13343323 12333433 11344433 11122111 11121111 111 1 1111 11111111 1 1111112111 1 111112211111 122222222111 122333333322111 222244665442211111 4555666655553112222 34577866876542111455 3467789AB98753123666 46777ACCOC9643124766 4 5677BBCCBA84 3 246776-13356A6BAA98S4334666 233567B9AA6544454665 22345355655455555442 2123333112324545431 3233422111123454431 22222221 2234453322 222222111122234322 112221112112122231 11211 11212122222 11 11 1121222 111 1111 111 111 11 11 1 111111 11111111 1111111 111111 11111 1111111 11 111 1111 1 A 182 222 OBSERVATIONS WITH TOTAL WEIGHT OF 323.1 COUNTING CIRCLE IS 1 . X OF TOTAL AREA A 111 1 2211111 22111211111 1211122211111 11111222111121 11121 11111 11 111 11111 1 2 1 11 11 11 1 1111 1 1122221 11111222222 21122113222222 211221111222221 211221111 11111 1111 21 11111 11111 1 111 11111 2 1111112 11 21 1111111 -11 1111111 1 11111 11 1 111 111 11211 111111 1211 1111 11111 1111111 1111111 1111111 111 11 11 11 11 1 1 1 1111 111111 1112*422 122(444211 1345443321 1 124444332 11213555321 1111122111 11111 11 11 11111 1 1111111 11222211 12223322211 1223222322121 3344444443211 231548776343211 7778897678952111 67BBB99BA9963Z11 68CCOCEECBA64211 89BCFIHIGB954222 79BCGGFGEOB55355 346AFHFEOCA75444 236AABCCC686B736 44578767689997 123332224489897 113322113357*76 21111 12366644 1223443 33 1 2221 12221 1111 122 122 111 1 11 11 1111 11 11111111 11 1111111 21111 1111111 1 1111 11111 1 111 111 183 \ ^  2MS 103 OBSERVATIONS WITH TOTAL WEIGHT OP 190.2 COUNTING CIRCLE IS 1.X OF TOTAL AREA 77798864*2211 444676899A8B8S431 1111111 1 13334*554576677655*312111111222121111 1111334543455666665212211111244*33444111 1 111333 2222 3*3 223 33 2123 31111123****444*2111 21223322111111112223333331112134444*31 233554333211222221112332233111111132222 22336666521211111122 22222231111 11111111 22566665221 11111111 112211 11111111 3455775321 11211 111 111 1 1111111 11115545553 1111 1111111 111111111 I 346565522211 11 1 111111 11111111112**6676**43 322 21 1111111111113*56*AA5*33222 11 1 111111 2 2 9 9 A A A A 3 3 2 2 1 1 33: 311 1111 1667788741111 1 1 1 33 3! 5 33 1 1 6666655 11111222355! 1 3331 55555 1111114433*5! i3331 111348655351 S33J 1555AA786644 .22 24458CDAAA51 1 24**ABOA8871 1 1111 68AAEHC77741 1 111111 • 66688CC344441 1111111 66666693333 111111 666666 1111 666 55 555555 5555555 5555555 555555 - 555 1111 111 21111111 1111 21111111 1 111 1111111 1111 222111111 11 111 1111 1112222332444211121 1 1111145656555433 111334667879 184 V... 325 OBSERVATIONS WITH TOTAL WEIGHT OF 1 0 U . 3 COUNTING CIRCLE IS 1.X OF TOTAL AREA 1 11 22 1211 111111 1111112 11111 1 111 1 1 1111 1 112211 11111222211 11111112222221 I 11 111 1 11 22221 1 111111111 11111 I I 11111 111 t 1111111 21 1111111 "11 1111111 1 11111 11 1 222222111 I 1 1 1 21 222 22 1 1 1 1 11111111111111111 11111111111111 I I 1111 1111111 2111111 2211111111 111111111 1111111 111111 11111 1111 1 1 11 1 1 111 1 111111 11111 11 111 111 111 1 111 1111 1111 1111 11 11 1 111 111 11 3 J 3 1 1 1111 11 111111 1 11123322 122333321 33433221 1 123333221 11113444211 1111221 1 1111 11 1111 111111 1 11111111111 122223222211 1223223432221 2334444*43221 233557766543211 778888767774111 67ABB99B977522 69CCDCODS985321 39COFFFGE974521 79BCDEOECB9442* 556ADEDCBA85433 336989AAA565766 1133*66556*7777 12333222336767 112222 132*686 11112 11 1 1 1 1 1 1 1111 11 1111 11111111 1111111111111 1111111 111111 11111 t 111111 11 1112111111 2222 1336553 1122233 1111 2 1111122 1 12221 1111 111 111 11 185 A.3 STEREONETS FOR DOMAIN D3 D3A 357 OBSERVATIONS WITH TOTAL JEIG-IT OF 1162.4 COUNTING :IRCLE IS 1.X OF TOTAL AREA 11 1 1 111111111 111 1 111 111 1 11111111 111111 1 11 1111111 111111111' 211111 11111 '111111 11 1111 12122111 '22222211 1 1 11111111' 11111111 111 22 134333 '34444' !34443' 132 • 43 .43221 1 1111 12211 11334' 143221 1 1 111111 1 1 1 111123' 133333 '22211111 11111 111 1 11111 35! [44443 111111 111111 1111111 1111133 J333331 112211 11 111 14' 1444 33 112221 111111111 11 '33321 122222 2 1111211 1 11111 122332 111 1122221 11 1111 111 112 112332 221222 221112233221 122233433321 11 11 1122 222322 1144344454321 1111 11 122 232221 4555886545434 11111 1 11 1111 122 344343 56539A9755345 11112211 11 113 344534 5 6 7 J 9 9 7 7 5 4 5 5 6 7 2311121121 11 11 2221 1 1 1 1 2 224445 56777864544677 44222321 1 1 2111111 1221111 11 11 222243 34677434423767 6542222331 1111111 1 11111 • 11 11 111232 23432233 12666 S55332233 1111111 111 222211 2221 11454 664232221 11222 11 1 111122 2221 111333 774331211 1111 1111 1 111 1111 11111 443332311 11111 112 11111 11111 2232221 111 111111 1 111 1 1 1122222111 111 2121122111 1 1 12111211111 11 11111 1111 1 11 11 1111 111 111 187 03FL 4 OBSERVATIONS WITH TOTAL WEIGHT OF 14.2 COUNTING : i R C L E I S 1.X OF TOTAL AREA 88 8 8 8 8 8 8 8 8 88 8HHH8B888 8B8 88HHPHHHH888 8 8 B 8HHHH9HHHM 88888MHN9999? 8388 9999 G G G J G G G G G J G G G G G G J G G G G G G S G G H H H i H H H H H H H H H H H H H H H H H H H H H H H H N 188 03CN 32 OBSERVATIONS WITH TOTAL WEIGHT OF COUNTING I I R C L E I S 1.X OF TOTAL AREA 67.1 A **2**55755*211111 111122455778775 8755**21111 1333333321*55 77788575**2221 1113***3311****57775 2211111 11133333313311113333 111 113333333331131111111 11133331113311111111 1111111 222222 11111111111111111111 1 1 1 * * * * * 2222222 111 2**111113*666****5668995222 22 2****11***66666458 66?CC995 2 2 2 2****2****1**2 2*****55 99009995 3 2222****2222 22 22 22**2669 900063 3 3 2 2 2 2 2 2 U J J H H H H 2222 3 36 69116777 U 222222HHHHHHrM 3399E999***** 55BBBSBB**** 5555BB 55 • 55555555 5555553 555 A A A 55355 5555555 11111 111111 1111111 111111 1111 A A A A A A A ! A A A A 11111 12211111111 12222222* 189 061 £{£££££{£ I f £{£££(££££ ££££99999££ 99£££££££ £££££££££ ££££££ »»*»*» ¥»*»¥* vvvvtvv *«*«« 1 * » m £££8i9»»»»> £$££ ££ » m * £££(££££ £ m £ £ £ £ 2 £ £ £ £ I £ £ £ « »»££££££9»»*9S£££ •••• I££££99»»»99?9 £S££999££ S £ S £ £ 9 9 f l O r r r O O Q o 6 9 9 6 9 9 9 9 9 1 £ i£££9999Q930S300036666669£££ ££££ 99906600000.4 9£ 6669 £ ££9996£J£ *3HV I S l C i dC X ' t SI 3 T 3 b i : S N I l K f l C O f ' C E dO l > 3 I 3 f T V l O i H i l A SKOI1«At 3S3C Z I I S S O 03 JN 293 OBSERVATIONS UIT1 TOTAL rfEIG-IT OF COUNTING ZIRCLE IS 1.X OF TOTAL AREA 13*3-4 111 1111 11111111211 11122111 1111111 1112 11 2 2 4 1 1111111 111111111 1112111111 111111 222221 333332 332333221 3344322211 33322221111 444 111111 3331 1 11111 1 1111 11111 1 11 1111111 11 3331 311 1111 11 11111 11 11 11111 1111221111 1111 3311 2221 21 1 111111122211 44222321 211 112 '22111 12211111 ••6523223311 112 222111 11111111 766332333 112 '22211 111 111 775232332 111 ?2211 375332222 11 1 543432311 11 11 2232221211 11 111 1122222211 1 11 2122222111 11 111 22112312211111 11 11 11111 111111 11111122111111 111*1122111111 1111111111111 111 11 11 111 11 1 111 11111 11211221 11122221 1111113221 11221112211 11222223221 1222322215 1223443436 1144545345 122255455 1122235*4 111223433 1122222 11222 2121 1111 1 11111111 1111 I 1111 1111 11 11 11111 111211 1111211 1 1122221 1112233222 2233433321 54455564431 65997555544 69ABA865455 79AA88646673 7 77865655778 677535524878 432333112777-21 112466 21 111343 11111 11111 1 1 111 191 DJHJ 75 OBSERVATIONS WITH TOTAL WEIGHT OF COUNTING CIRCLE I S 1.X OF TOTAL AREA 283.5 111 I 111 111 11111 222 22222 222222 222222 222222 2222 111 11 11 11 1111111 11111222 122222 11111 2211 1111111132 1111111223 111113222 322 11 3333333 4*3333333 111 4444**1 I 11 1 111****5*44 11111 1 1 1 3 3 * * * * * * * 11111111 I I 333**688***11111111 22 '33638*****211111 336533331133333**2 111 266633353 1333332 2665*3333 115535333 1 333533 33333333 33335333 333335 11111 1 1 1 1 * * * 11***442 1 25555522 111 1111 11111 11111 11111 3515555486333 11 333348884486337 3**4* 33377885GC03B777**** 337AAAGDHHC3FB73844* AAEEIBGGGCJGF777444 3 7 7 7 F F F J J J F C C 8 3 3 8 * * * 33777BJEEFFSC73****4 333778EAACG? 3** 1 1557766777*11 1111114367777422111 111111143**41222111 1 1111111 33*11221111 1111 11 11111 111 1111 111 11 333 11111 192 D3MS 55 OBSERVATIONS K i l l TOTAL HEIG-IT OF 113.9 COUNTING : i R C L E IS 1.X OF TOTAL AREA 33254555*521 123342*677787768655 13****4*6*77788898565 1223445333366678977633 112332222 3322334332 1 1111122232343211111 12221112221111133 11111111 22333 11 11 13663 1111133*446 1122555524* 12222555422 1 2 2 2 2 U 4 C C 111111AAA 22222 2222222 2222222 2222222 21 222 111 3 A A A A 88 BB 88 A CCCCCCC21 111111 ECOOCD3322 1111111 34*****22222335553111 3*32333332233357735311 122112222222557755532 1111112213355777*222 AA 1 1 1 1 2 2 3 3 5 B B U 4 4 2 2 A A A 2255855522222 A A A * 988865522222 • A t 3366666552222 336666662222 333366 33 55555 5555555 5555555 555555 222 2255222 225555222 222555522 222555522 222532 33333 3333333 33333333 3333333 333 555 5555555 55555555 5555555 5555 11 11111 1 2211 122222223 11 193 OJM» 123 OBSERVATIONS WITH TOTAL WEIGHT OF COUNTING ZIRCLE IS 1.X OF TOTAL AREA 402.4 111 11111 111111 111111 111111 1111 111 111111122 11111111122 11111111112 11 11 111 11111 111 1111 1 111 1 21111 3333222 1211111332222222 21111111 3333333 1 11333333 111336666661 11 1226666666661 1111111 221136646897433 111111 3311 44377433332112Z21 336533432233333442112221 264643333 23333 321122111 353432233 147655322 33222222 222222222 2222222 222222 22222222 22222222 222222 11112221 112J31111 1223444 1 33554442 1 11 135555532 111 3325555465332 11 22233667425422223333 2Z255564BB9S855S33333 225777B9CC83B85353333 77AA08BBB83BB55533355 2SS5B9BEEEB38822S3333 225S5BOAABB3852333352 11444557*77886 233 111223555445553 12222223245555422 11 122222 323332322111 2232233111 222211 112211 1 1 111 1111111 11111111 1111111 1111 222 1 1111 111 194 A.4 STEREONETS FOR DOMAIN D4 276 OBSERVATIONS WITH TOTAL WEIGHT OF 343.4 COUNTING : i P C L E IS 1.X OF TOTAL AREA A 1 1 111 11 111 12222233211122 11111 22222233323332211 1111111 3333334332313222111 1111111 11113334322233322221111 11 111111 1222333212222222221223 21111 233333323222221111232; !2221 1 1 11 1211222222122222122233! 32111122 223 11 111222 111122332333! •221 1 222 22231 11 1111123223333! '1211 222 222221 11 !211 1111122332353" .2211111 222 222221 111 11111 112122334 522222 11 1 1 21 322221 111 111111 111122454 .542222111211 2211 11111 11 1111 111 24344 .5542222112111 1 1111111 1111 111134444 .443221211 1222 1 12111111 11111245! 553212333434442 111221 1122245! !5386352224S3332 2221 122134! '466654532398662 1111121 1134&7! I7666SS5343876661 1111 11222221 24466! '777465654777666 1222111 1122111 144554 .756755523445643 11 222331 1111111 • 111 232334 •433411232144533 112333221 1222221 11111224444 3221111321143 112333221 221221 1 11112211112 S21111111 11 11 1 1112331111 2222111 11122222121 11111 111 1132211 222211 11133222221 11 111 1 222 1222 12222212222212 1 2111 2 1111 123322332112111 11111 11 1 12333333222122 11111 23333332222111 1 1 11 11222212111111 1 1 11111121111 11 1 111 111 1 111 11 1 196 D4FL 4 7 O B S E R V A T I O N S WITH T O T A L WEIGHT OF CO U N T I N G Z I R C L E I S 1.X OF T O T A L AREA 73.2 111111 11111111 22223331221 33331 11 1111 1 222233565855546A844431 11 1115555522 22**556897559BB8A38***33 11111331 11111*5777753*1 ****5*5 777ACCA8778A63111 111113331 1111 58838755*1 1111114666AAC879753111111 1111113311 1113*7783875S 113555657B?662***44111 1111111111 1113*4*****1 1 1 1 1 1 3 3 1 3 6 6 6 6 8 7 7 5 2 4 7 4 2 7 7 7 7 * 111 1133333*331 11111113 31344665 5687 99 7866663 n u : 1333111111 1111111111333447EB9 997BB66653 1 33 3: 533 51 111111 AAAAEE3747B663333 333: 3311 2222 69999EEB444 3333 1111 111 22222222 2699999622 1 22222222 222599666 2222222 2222222 222 2222222 222222 AAA 66 AAAAA 6 6 6 5 H A A A A A A 6666SHHAAAAA 666656HAAAA 6 6 6 6 6 6 A A A 666 222222 222444222 2222444222 2224444222 222444222 7 1111 333333 35333333 3333333 1333331 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 197 04CS 25 OBSERVATIONS WITH TOTAL WEIGHT OF COUNTING : i R C L E IS 1.X 3F T3TAL AREA 44.1 2222222 222222 22222222222 22444444 2222222222222222 222555557222 222222442 22 2Z22222428BBCELL5222 22224444 4222 2222222225JBEL00JJGD22522 22 24442 2 22 22 2 2 2 2 2 2 2 2 2 2 5 ? J J J L L J D D C 5 2 2 2 2 2222222 22?5JGGGAD07AAAAA 22 2 2 2 2 6 A A A A 3 7 A A A A A A 2 2222222 3333333S77AAAAA 222222222 22222222 222222 0 OO 0 0 3333333B777777 333353 7777 22222 222222 2222222 K KK KK 222222 KKKKKKK 22222 KKKKKK4K KKKKKC KK 22222 2222222 2222222 2222222 22222 ODD DOOO 0000 0000 OODO 444 44444 000 444444 4444444 444444 444 3333 333333 33333333 3333333 2 33333 22222222 222222 198 D4SR 13 OBSERVATIONS WITH TOTAL WEIGHT OF COUNTING :IRCLE IS 1.X DF TOTAL AREA 15.6 7777777 7 F F F F F 7 777777777FFF0O0ODOG 777777777 7FF00OO00OGB 77 909999 39999999 99999999 999999 F O O O O O 8 8 S 8 B88KBBB BBBBBB9B '979LLBB SB SB B 9997999LLB88BB 999999999 B S 999999 0030 DODDODO OOODDODO DDOOODO 0000 FFFFF F F F F F F F F F F F F F F F F F F F F F F F F 9 8 8 9 8 8 8 8 B 8 S B 8 8 8 S 8 S 3 8 8 8 S 8 8 8 8 8 199 D 4 J M 194 OBSEJVATIONS WITH TOTAL WEIGHT OP 707.5 COUNTING CIRCLE I S 1.X OF TOTAL AREA 1 1 333 33332 111 333331 112211 333331 12121111 433331 111111211 1 3311 1111 1 1112211 1 11111 12 1111 1 122221 22 22222 2221 11111 11111 51111 1111 11223 532 111111 1 2221 11 223 3222 11111111 11222431 221 2222 11111111 112444531 1333 331 111111 112444331 12213 511 1 1112441111112222 111 22322111112222 11 1 111222 111133 2 111111 111111 111111 111 11111 21 111 221 222 22 11111222 111122222111 333334433111 211133342111111 1 233333421111111111111111 1 23333332312111 111222111 112 211222222121111111222221 122 11122? 111122222223211 222 1112112222323211 222 111111222223322111111 222 1111113333222221111122 11 22465653322112211 134356653222122111 2445455432132111335 1356653212444545552 2224666*9846333574443 22224565888756434A9873 1155 79*9 7786 5644 8887771 3 44 7788 99575743 777777 144665866755313635554 1111243445533311111 34444 -11111235455322 1111 44 111122221122111 12233322221111 11134222332111 11 122232123333221 1111 133333442222111 11111 13334434332222 11111 33454432322111 11111 111122332222111 1111 11221221111 1 111111 1 1 200 OIHJ 104 0BSERY»TIONS WITN TOTAL WEIGHT OF COUNTING CIRCLE IS 1.X OF TOTAL AREA 319.3 1 11 1 333 1 333333 333333 333333 333333 33 22222 222222 I 222222 I 222222 I I 22222 11 53 333 4*3 444 441 411 1 1111 111121 11122221 112222251 122465553 115555333 5533333 333333 33 11 222 1111221 1222222 222222 222 11 11 3433345 111111 3344455 1111111114*44455 111111111 4455 11112111 1 1 1 11 11 111 11 111111 21111 1111 111 111 11111 121223222112 1111 1123433222122* 2322221123*444221 255 33323323234553311 555 22222222344432311111555 112222222244332211111555 11 115455433321211355 227**89*4321113111 25799**843321121111 267989974311 1111 7798774211 1111 ****85*A7722 444*4454655311 **44 33888875553551 444444 77777*35557731 444444 377773735777311****44 111 3333355 3511111 44444 111111355735111111111 14411 11111332233211111111 111111 111134436352211 11235366763221 45664332 113333222 1123333331 2222235433111 223334331111 123333432111 111132311 1 1111 111111 11111 111 201 04HS 82 OBSERVATIONS WITH TOTAL 'WEIGHT OF COUNTING ZIRCLE IS 1.X OF TOTAL AREA 135.? 1111111 233333 111111111121133*44*32 111111112225345445443242221 121 121 1222535778386790C43321 112224443311 223333457379EFFCCA933422 3333334568DEEED399A52111 114567CC009A955444411 113344657BA88255555441 111123313444666642375477776 11111113312 333 5444 6 5 496766661 11111111 1112259766448744311 11113311 44448864244331111 1111 1111111 33555834233 2211 111111121111111 1353535412 111111111111111111355333 1211222134444*332 111 111 455554332 11 1244555433 1123332222 1111122222311 111233331111 1 2222 33 52 22222211 1111111 111 4 44 4 4 1111111 111 1111 11183836 118888864 188888666 666666 66 17771 33177777 4444B777777 44444AB77777 44444487777 444443666 444 444 111111 222 1112221152222 11112221222222 11122222221111 1112221221111 1 111 4444 4444 5444 5444 44 4 2222 222222 22222222 2222222 22222 11 111 11111111 111111 I 202 04MA 183 OBSERVATIONS WITH TOTAL WEIGHT 0= COUNTING :iRCLE IS 1.X OF TOTAL AREA 455.2 ' 1 111 11 1111 11 1 1111111 111111 1111 11111 111111 11111122 333445543 1111111 11334445564 112211111 433344455 1111 111 11 1 122222121111 1112222221 11111111 11111 1 11 334422 1112 1 2222 111222 111111 11111 111 1 11 1 1 2222 222222 222222 222222 222222 22 11111 111111 I 111111 I 111111 II 11111 11 32 222 332 333 33 3 22221 2222231 22443332 113333222 3322222 222222 22 111 11 111111 111111 111 111 111111 111112 111123 11123 3 112 1 2 111112 1 1 2222 1222222 112121 11111 11111 1111 22 3313 22 24 3 2114 33 2111433 22111333 221111233 3221112111 32221121111 3211 1111 211 1111 511 3311 3333 3331 2553333 366232555333 666533555533 522443256643 • 2222432364 22222122 221 111 1 2221 112221 12211 1111 1 111 1 111 11 I 203 APPENDIX B. PROGRAM SWEDGE B . l OBJECTIVE Program SWEDGE was developed f o r two s p e c i f i c t a s k s . The f i r s t g oal i s to be able t o evaluate the s t a b i l i t y of wedges of known or assumed geometry, shear s t r e n g t h parameters, and water pressures by c a l c u l a t i n g a f a c t o r of s a f e t y . This c a p a c i t y i s r e q u i r e d to determine whether wedges i d e n t i f i e d i n the a n a l y s i s of s t r u c t u r a l data are l i k e l y t o f a i l i f they are allowed t o d a y l i g h t . The second o b j e c t i v e i s t o c a r r y out a back a n a l y s i s study t o determine a range of shear s t r e n g t h parameters that would s a t i s f y the c o n d i t i o n o f l i m i t i n g e q u i l i b r i u m f o r a wedge of s p e c i f i e d geometry assuming t h a t FOS=l and water pressures are known. B.2 THEORY A c l o s e d form mathematical s o l u t i o n has been developed f o r the c a l c u l a t i o n of f a c t o r of s a f e t y by Hoek, 1981. This s o l u t i o n uses a vector algebra approach t h a t i s computationally more e f f i c i e n t than other a n a l y t i c a l methods. The appendix of Rock Slope Engineering t h a t presents t h i s s o l u t i o n i s reproduced on the f o l l o w i n g pages. A b r i e f d i s c u s s i o n on groundwater assumptions used i n t h i s model i s r e q u i r e d . The program uses a l i n e a r pore pressure d i s t r i b u t i o n t o c a l c u l a t e u p l i f t f o r c e s due t o groundwater. That i s t o say, pressures are assumed t o be zero at a l l f r e e faces and then increase l i n e a r l y t o a maximum value H w at some p o i n t along the l i n e of i n t e r s e c t i o n of the two f a i l u r e planes. The maximum p o s s i b l e value of H w i s assumed t o be the f u l l height of the wedge, H. The groundwater 204 pressure d i s t r i b u t i o n i s i l l u s t r a t e d i n an i s o m e t r i c diagram i n Fig u r e B.1. The maximum pore pressure achieved i n the berms at Eq u i t y i s l i k e l y l e s s than the maximum t h e o r e t i c a l value because most berms are somewhat f r a c t u r e d by b l a s t i n g so any excess pore pressures u s u a l l y d i s i p a t e r a p i d l y because of high p e r m e a b i l i t y . I f f r e e z i n g occurs at the f a c e , water i s not allowed to d r a i n and pore pressures may exceed the t h e o r e t i c a l maximum value by s i g n i f i c a n t amounts. For back a n a l y s i s of the sm a l l berm s c a l e f a i l u r e s i t i s recommended that u=0 be input i f the berm appears dry or piezometer monitoring i n d i c a t e s that the water t a b l e i s w e l l below the berm face. I f water i s present i n the berm u should be assigned a value of 0.5H tv/6. I f the op p o r t u n i t y a r i s e s t o back analyze a f u l l s c a l e p i t w a l l f a i l u r e then pore pressures should be measured w i t h piezometers i n the f a i l u r e or i n a nearby s e c t i o n and the average pore pressure d i s t r i b u t i o n should be c a l c u l a t e d before i t i s input i n t o the s t a b i l i t y a n a l y s i s . 205 L i s t i n g of "WEDGE SOLUTION FOR RAPID COMPUTATION" from Hoek and 1981. SHORT SOLUTION Scope of s o l u t i o n The s o l u t i o n p r e s e n t e d i s f o r the c o m p u t a t i o n o f the f a c t o r o f s a f e t y f o r t r a n s l a t i o n a I s l i p o f a t e t r a h e d r a l wedge formed i n a roc k s l o p e by two i n t e r s e c t i n g d i s c o n t i n u i t i e s , the s l o p e f a c e and the upper ground s u r f a c e . I t does not take account o f r o t a t i o n a l s l i p o r t o p p l i n g , nor does i t i n c l u d e a c o n s i d e r a t i o n o f those cases i n w h i c h more than two i n t e r s e c t i n g d i s c o n t i n u i t i e s i s o l a t e t e t r a h e d r a l o r ta p e r e d wedges o f r o c k . In o t h e r w o rds, the i n f l u e n c e o f a t e n s i o n c r a c k i s not c o n s i d e r e d i n t h i s s o l u t i o n . The s o l u t i o n a l l o w s f o r d i f f e r e n t s t r e n g t h p a r a m e t e r s and water p r e s s u r e s on the two p l a n e s o f weakness. I t i s assumed t h a t the s l o p e c r e s t i s h o r i z o n t a l , i e the upper ground s u r f a c e i s e i t h e r h o r i z o n t a l o r d i p s i n the same d i r e c t i o n as the s l o p e f a c e o r at 180° t o t h i s d i r e c t i o n . When a p a i r o f d i s c o n t i n u i t i e s a r e s e l e c t e d a t random from a s e t o f f i e l d d a t a , i t i s not known whether : a) the p l a n e s c o u l d form a wedge ( the l i n e o f i n t e r s e c -t i o n may plu n g e too s t e e p l y t o d a y l i g h t i n the s l o p e f a c e o r i t may be too f l a t to i n t e r s e c t the upper ground s u r f a c e ). b) one o f the p l a n e s o v e r I l e i the o t h e r ( t h i s a f f e c t s the c a l c u l a t i o n o f the normal r e a c t i o n s on the p l a n e s ) c) one o f t h e p l a n e s l i e s t o the r i g h t o r the l e f t o f the o t h e r p l a n e when viewed from the bottom o f the s l o p e . In o r d e r t o r e s o l v e t h e s e u n c e r t a i n t i e s , the s o l u t i o n has been d e r i v e d In such a way t h a t e i t h e r o f the p l a n e s may be l a b e l l e d 1 ( o r 2) and a l l o w a n c e has been made f o r one pl a n e o v e r l y i n g t h e o t h e r . In a d d i t i o n , a check on whether the two p l a n e s do form a wedge i s i n c l u d e d In the s o l u t i o n a t an e a r l y s t a g e . Depending upon the geometry o f the wedge and the magnitude o f the w a t e r p r e s s u r e a c t i n g on each p l a n e , c o n t a c t may be l o s t on e i t h e r p l a n e and t h i s c o n t i n g e n c y Is p r o v i d e d f o r In the s o l u t i o n . Notation The geometry o f the p r o b l e m i s i l l u s t r a t e d i n the m a r g i n s k e t c h . The d i s c o n t i n u i t i e s a r e denoted by 1 and 2, the upper ground s u r f a c e by 3 and the s l o p e f a c e by U. The d a t a r e q u i r e d f o r the s o l u t i o n o f the problem a r e the u n i t w e i g h t o f the r o c k y. the h e i g h t H o f the c r e s t o f the s l o p e above the i n t e r s e c t i o n 0, the d i p <r and d i p d i r e c t i o n a o f each p l a n e , the c o h e s i o n c and the f r i c t i o n a n g l e • f o r p l a n e s 1 and 2 and the ave r a g e w a t e r p r e s s u r e u on each o f the p l a n e s I and 2*. I f the s l o p e f a c e overhangs the toe o f the s l o p e , the index n i s a s s i g n e d the v a l u e o f - I ; i f the s l o p e does not o v e r h a n g , n " Plane 1 overlies plane 2 206 Other term* used i n the s o l u t i o n a r e : F - f a c t o r o f s a f e t y a g a i n s t wedge s l i d i n g c a l c u l a t e d as the r a t i o o f the r e s i s t i n g t o the a c t u a t i n g s h e a r f o r c e s A • a r e a o f a f a c e o f the wedge W « w e i g h t o f the wedge N » e f f e c t i v e normal r e a c t i o n on a p l a n e S « a c t u a t i n g s h e a r f o r c e on a p l a n e x,y,z • c o - o r d i n a t e axes w i t h o r i g i n a t 0 . The z a x i s i s d i r e c t e d v e r t i c a l l y uowards, the y a x i s i s i n the d i p d i r e c t i o n o f p l a n e 2 a " u n i t v e c t o r i n the d i r e c t i o n o f the normal t o p l a n e I w i t h components ( a x , a y t a z ) b " u n i t v e c ' o r i n the d i r e c t i o n of the normal t o p l a n e 2 w i t h components ( b x , b y , b z ) f « u n i t v e c t o r i n the d i r e c t i o n o f the normal to p l a n e * i w i t h components ( f x , f y , f z ) g • v e c t o r i n the d i r e c t i o n o f the l i n e o f i n t e r s e c t i o n o f p l a n e s 1 and k w i t h components ( g x , g y , g z ) l • v e c t o r i n the d i r e c t i o n o f the l i n e o f I n t e r s e c t i o n o f p l a n e s I and 2 w i t h components (t x,£y,t z) I f i t i s assumed t h a t the d i s c o n t i n u i t i e s a r e c o m p l e t e l y f i H e d w i t h w a t e r and t h a t t he w a t e r p r e s s u r e v a r i e s from t e r o a t the f r e e f a c e s at a maximum a t some p o i n t on the l i n e o f i n t e r s e c t i o n , then uj • u j » yw\,/b where H w i s the o v e r a l l h e i g h t o f the wedge. i - - i z q • component o f g In the d i r e c t i o n o f b r - component o f a In the d i r e c t i o n o f b k - |J|J - f x 2 * i y 2 + i z2 I - W/A2 P " A l ' A Z " 1 - " i M ? "I n 2 - N 2/A 2 ) Assuming c o n t a c t on b o t h p l a n e s \li\//k - SA 2 J m l " N l / * 2 1 * , » /. V c o n t a c t on p l a n e 1 o n l y d e n o m i n a t o r o f F » SJ/AJJ m2- N 2/A 2 1 c o n t a c t on p l a n e 2 o n l y d e n ominator o f F • S 2 / A 2 J 207 Sequence of c a l c u l a t i o n s The factor of safety of a tetrahedral wedge against sliding along a line of intersection may be calculated as follows : 1. (a„ ,a y ,a z) - (S i n*!. S in ( a t - a 2 ) , Slni|>[ .Cos ( a f a 2 ) , Cos*i) 2. ( f x , f y , f z ) • (Sini|i,,.SIn(ai,- a 2 ) , S i n i | i u . Cos ( a ^ a 2 ) , Cos<ii,} 3. by - Sin^j U. bz - Cosi|>2 5- 1 ' a x b y 6. g z - f x a y - f y a x 7. q - b y ( f z a x - f x a z ) • b z g z 8.. If nq/i > 0, or if n ( f z - q/i) Tani'j -• /I - f z z and 03 * a,, » (I - n) i/2, no wedge is formed and the calculations should be terminated. 9. r - a y b y • a z b z 10. k - 1 - r 2 11. I - (yHq)/(3g z) 12. P - - b y f x / g z 13- n 4 - { (Z/k)(a z - rb z) - pu ().p/|p| \h. n 2 - {(I/k)(bz - ra z) - u2) 15. mj - (Ia z - ru 2 -• pu]).p/|p| 16. m2 » (Ib^ - rpu[ - u2) 17. a) If nl > 0 and n 2 > 0, there is contact on both planes and f • (ni .Tant i* n 2 .Tan* 2 • | p |c ( • c 2) /k/1 li \ b) If n 2 < 0 and m( > 0, there is contact on plane 1 only and mj.Tan ?j + | p |C i U 2(1 - a/) + ku\ .* 2(ra 2 - b z)Zu 2)* c) If n t < 0 and m2 > 0, there Is contact on plane 2 only and m 2.Tant 2 c 2 F - • T U 2 b y 2 + k p 2 U ! 2 • 2(rb z - a 2 )plui)* d) If m. < 0 and m2 < 0, contact Is lost on both planes and the wedge floats as a result of water pressure acting on planes 1 and 2. In this case, the factor of safety fa l ls to zero. 208 APPENDIX B.3 LIST OF VARIABLES VARIABLE FUNCTION TYPE AX x component of u n i t vector perp. t o plane 1 r AY y component of u n i t vector perp. t o plane 1 r AZ z component of u n i t vector perp. t o plane 1 r A$ b u f f e r f o r p r i n t i n g of f i n a l t i t l e s AUTOWAT$ c o n t r o l v a r i a b l e f o r groundwater assumption s BY y component of u n i t vector perp. t o plane 2 r BZ z component of u n i t vector perp. t o plane 2 r CON$ c o n t r o l v a r i a b l e f o r i n p u t , screen/data f i l e s C l cohesion on plane 1 r C2 cohesion on plane 2 r CHANGE i n d i c a t o r f o r which v a r i a b l e t o change i CFLAG i n d i c a t o r f o r f a i l u r e type i CLOW i n i t i a l cohesion i n s e n s i t i v i t y subroutine r C ( I I ) cohesion at loop I I of s e n s i t i v i t y a n a l y s i s r COH$ s t r i n g v a r i a b l e h o l d i n g cohesion f o r p r i n t s D I P l d i p angle on plane 1 ( f a i l u r e surface) r DIP2 d i p angle on plane 2 ( f a i l u r e surface) r DIP3 d i p angle on plane 3 ( c r e s t ) r DIP4 d i p angle on plane 4 (face) r DIRl d i p d i r e c t i o n on plane 1 ( f a i l u r e surface) r DIR2 d i p d i r e c t i o n on plane 2 ( f a i l u r e surface) r DIR3 d i p d i r e c t i o n on plane 3 ( c r e s t ) r DIR4 d i p d i r e c t i o n on plane 4 (face) r DELTAC incremental change i n cohesion per loop r DAT$ v a r i a b l e i n d i c a t e s whether data t o be s t o r e d s DATFILE$ name of data f i l e s DATFILE2$ name of data f i l e used i n input s DEGRAD conversion f a c t o r , degrees t o radians r DELTAPHI incremental change i n f r i c t i o n angle r DOT p o s i t i o n of decimal p o i n t i n fos i FX x component of u n i t vector perp. t o plane 4 r FY y component of u n i t vector perp. t o plane 4 r FZ z component of u n i t vector perp. t o plane 4 r FLAG c o n t r o l v a r i a b l e used i f no wedge formaed i F f a c t o r of s a f e t y r POS(II,J) f a c t o r o f s a f e t y i n s e n s i t i v i t y a n a l y s i s r FOS$ s t r i n g v a r i a b l e h o l d i n g f a c t o r of s a f e t y s GAMMAD dry d e n s i t y of rock r GZ z component of vector along i n t e r s e c t i o n 1,4 r H height of wedge, toe t o c r e s t r H$(I) v a r i a b l e holds f a i l u r e mode header s I z component of u n i t vector i r I I counter i J counter i K length vector i squared r L used r LIN$ b u f f e r f o r p r i n t i n g s e n s i t i v i t y l i n e s LWIDTH l i n e width i Ml s t r e s s on plane 1 i f contact only on plane 1 r M2 s t r e s s on plane 2 i f contact only on plane 2 r 209 VARIABLE FUNCTION TYPE NETA -1 i f face overhangs, e l s e 1 i N l s t r e s s on plane 1 i f contact on both planes r N2 s t r e s s on plane 2 i f contact on both planes r PCON$ c o n t r o l s hardcopy output s PHI1 f r i c t i o n angle on plane 1 r PHI2 f r i c t i o n angle on plane 2 r PHILOW minimum f r i c t i o n angle i n s e n s i t i v i t y a n a l . r PHIINC f r i c t i o n angle increment r PHI(J) f r i c t i o n angle i n c u r r e n t loop of sens, study r PAD c o n t r o l s padding of b u f f e r f o r l e f t j u s t i f y i PHI$ s t r i n g v a r i a b l e holds value of p h i s Q component of vector g i n d i r e c t i o n of b r R component of vector a i n d i r e c t i o n of b r SENS$ c o n t r o l s whether s e n s i t i v i t y study d e s i r e d s SPEED$ c o n t r o l s d e t a i l of screen output d u r i n c c a l c s s SUBFLAG2 used i n r e t u r n from subroutine i SUBFLAG3 used i n r e t u r n from subroutine i SPEC$ c o n t r o l s whether c-0 l i m i t s input or assigned s U l pore pressure on plane 1 r U2 pore pressure on plane 2 r UMAX maximum t h e o r e t i c a l pore pressure r UNDER$ s t r i n g v a r i a b l e used f o r u n d e r l i n i n g s WRATIO r a t i o of avg. water pressure t o maximum r Note: TYPE i n d i c a t e s v a r i a b l e type, i . e . r=real v a r i a b l e (e.g. 1.73) i=integer v a r i a b l e (e.g. 33) and s = s t r i n g v a r i a b l e (e.g. " S - l " ) 210 APPENDIX B.4 FLOW CHART FOR PROGRAM SWEDGE INTERACTIVE DATA INPUT SUBROUTINE INPUT PROGRAM OPTIONS IF CON*=YES SKIP DATA ENTRY INPUT REQUIRED VARIABLES, I .E . GEOMETRY, SHEAR STRENGTH, GROUNDWATER CONDITIONS IF DATI=tC SKIP DATA STRORASE TO FILE DATA STORAGE SUBROUTINE { 6 0 TO U K ) PRINT ALL DATA TO DATA FILE RETURN TO DATA MODIFICATION SUBROUTINE IF SUBFLAB3*! DATA RETREIVAL SUBROUTINE 1084, OPEN READ CLOSE ( G O TO nag) READ ALL PARAMETERS FROM EXISTING DATA FILE 211 DATA ECHO AND MODIFICATION SUBROUTINE (60 SUB 1864) (BO SUB 1299) OPEN PRINT PRINT CURRENT VALUES OF ALL PARMETERS ON SCREEN INDICATE HHAT VALUE OF VARIABLE TO BE CHANGED IF ALL CHANGES COMPLETED CHANGED INPUT DESIRED CHANGES MAIN CALCULATION SUBROUTINE CONVERT ALL ANGLES TO RADIANS 60 TO SENSITIVITY SUBROUTINE IF SENSt=Y DETERMINE COMPONENTS OF ALL UNIT VECTORS EVALUATE FORCES DETERMINE FAILURE MECHANISM FACTOR OF SAFETY RETURN TO SENSITIVITY SUBROUTINE IF SUBFLAG2=l PRINT RESULTS ON SCREEN AND LINE PRINTER IF DESIRED 212 SENSITIVITY STUDY SUBROUTINE (SO SUB 133l) END" INPUT C t PHI IF SPECMY ELSE ASSIGN STANDARD RANGE LOOP THROUGH ALL COHESIONS INCREMENT C INCREMENT C SO TO MAIN CALCULATION ROUTINE 60 TO PRINTING SUBROUTINE ECHO PRINT INPUT DATA SUBROUTINE PRINT ALL DIMENSION PARAMETERS ON LINE PRINTER BYPASS PRINTING SHEAR STRENGTH PARAMETERS IF SENS$=Y PRINT SHEAR STRENGTH PARAMETERS PRINT PORE PRESSURES 213 PRINT SENSITIVITY RESULTS SUBROUTINE PRINT PRINT HEADERS LOOP THROUCH ALL COHESIONS ADD C(II) TO BUFFER LOOP THROUGH ALL FRICTION ANGLES LINE PRINT BUFFER PRINT FAILURE MECHANISM, STRESS CONDITIONS AND TITLE RETURN, vl29 214 B.5 PROCEDURE FOR USE Program SWEDGE i s menu d r i v e n , w i t h the c a p a b i l i t y t o enter data from a screen or a data f i l e on d i s k . Values of a l l parameters can be s e l e c t i v e l y a l t e r e d before each run. The program can c a l c u l a t e a s i n g l e f a c t o r of s a f e t y f o r a wedge of s p e c i f i e d geometry, shear s t r e n g t h and water pressure, or i t can c a r r y out a s e n s i t i v i t y study over a f u l l range of c and f6. Because the procedure f o r use v a r i e s w i t h the type of a n a l y s i s and options s e l e c t e d i t i s not p o s s i b l e t o giv e step by step i n s t r u c t i o n s . Instead, each option i s explained below. 1. "Do you want t o use e x i s t i n g data?" - Yes i f data already on f i l e , note that each e n t r y can be a l t e r e d . - No i f new data deck has t o be entered. 2. "Do you want t o do s e n s i t i v i t y study?" - Yes i f a t a b l e w i t h F.O.S. f o r expected range of c and 0 i s de s i r e d , e.g. f o r back a n a l y s i s . - No i f only one F.O.S. i s d e s i r e d f o r s p e c i f i e d paramemeters 3. "Do you want hardcopy?" - Yes i f l i s t i n g of input data and r e s u l t s on p r i n t e r d e s i r e d . - No i f output d e s i r e d only on screen. 4. "Do you want t o observe?" - Yes i f c,0, and F.O.S. t o be p r i n t e d on screeen during each i t e r a t i o n so progress can be observed. S l i g h t l y slower, but valua b l e t o see i f shear s t r e n g t h i n r i g h t b a l l park. 5. "Name of f i l e i n which data i s stored?" - Enter name of data f i l e from which e x i s t i n g data i s t o be taken. Should be format " .dat". 6. " I n d i c a t e Parameter t o be Changed! I f a l l OK type 0." - at t h i s p o i n t values of a l l parameters l i s t e d on screen. Simply input number that precedes d e s i r e d parameter or 0 i f no f u r t h e r changes. 215 7. "Name of storage f i l e i f new? E l s e h i t r e t u r n " - name of data f i l e t o which new or modified data i s t o be w r i t t e n . I f i t i s the same f i l e from which data was read then h i t r e t u r n . 8. At t h i s p o i n t data and r e s u l t s are p r i n t e d i f i n s i n g l e F.O.S. mode and program i s terminated. 9. "Do you want t o s p e c i f y c and p h i range?" - Yes i f range other than d e f a u l t i s d e s i r e d . - No i f d e f a u l t range c=0 t o 20 kPa, incremented by 2 0=20 t o 50 deg, incremented by 2 10. "Back a n a l y s i s r e s u l t s p r i n t e d . 11. " A n a l y s i s t i t l e ? " - Input d e s i r e d t i t l e , e.g. "Wedge 4 - Dry water c o n d i t i o n s " 12. "Do you want t o s p e c i f y water pressures?" - yes i f d e f a u l t value p r i n t e d on screen i s not d e s i r e d . D e f a u l t i s t h e o r e t i c a l maximum, i . e . HwXH/6. 216 APPENDIX B.6 PROGRAM LISTING 1000 ' 1 1 I I 1 1 1 I I H I I » H 1 1 *************** H M I I H H m W W H W W H W H H m H 1001 ' SHORT HEDGE l£02 1 m W f « » « * * H H r * H r t « « * « * « * « t * « # » I H H f l * H * » t l « * # * « 1003 'A PROSRfW TO EVALUATE THE STABILITY OF A WEDGE USING DR. KIEK'S VECTOR 100* 'SOLUTiON IN ROCK SLOPE ENG. APPENDIX 2. FOR DETAILS SEE DOCUMENTATION. 1005 1006 1087 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 ' t i i i i i i i i i t i t M i n i i i i i i H m i M i i H H t i i i i i m n n i i i m i i n i i t i i i i i i H i 11 H t t<l t 11 I I I 11 H 11 M I I I I M 11 I M t H It H H H t H I U M l H I H H I I I I I I  I H It I I I • lOTEHRCTIVE _ DflTfl _ INPUT _ SUBROUTINE _ THIS SUBROUTINE PROMPTS FOR ALL REQUIRED PARAMETERS IN ANALYSIS. CLS PRINT" m nmSHORT WEDGE PROSRAMtH»*m«f*«««*»M*«**«" PRINT CHRIU0P DATA INPUT" PRINT" INPUT-DO YOU WANT TO USE EXISTING DATA C!LE? Y/N";CON$ INPUT"DO YOU WANT TO DO SENSITIVITY STUDY? Y/N"iSENS$ INPUT-DO YOU WANT HARDCOPY ON PRINTER? Y/N";PCON$ IF SENS*="Y* THEN INPUT'DO YOU WANT TO OBSERVE? Y/N"!SPEED* IF CCN$=°Y" GOTO 1084 INPUT'DRY UNIT WEIGHT OF ROCK (n/i»«3) "5GAMMAD INPUT'VERTICAL HEIGHT CREST ABOVE TOE (n)";H PRINT" PRINT-PROPERTIES OF 1ST SIDE OF WEDGE: PLANE 1" PRINT" INPUT-DIP FOR PLANE 1 "?DIP1 INPUT'DIP DIRECTION FOR PLANE 1 ";DIR1 INPUT'CTJHESION FOR PLANE 1 ";C1 INPUT'FRICTIDN ANGLE FOR PLANE 1 "JPHIl PRINT" PRINT-PROPERTIES OF 2ND SIDE OF WEDGE: PLANE 2" 1 IF DOES NOT OVERHANG, 1 IF OVERHANGING" PRINT-SPECIFY NETA: PRINT' INPUT'DIP FOR PLANE 2 INPUT-DIP DIRECTION FOR PLANE 2 INPUT-COHESION FOR PLANE 2 INPUT-FRICTION ANGLE FOR PLANE 2 PRINT" PRINT"ORIENTATION OF TOP PLANE: PLANE 3" PRINT" INPUT-DIP FOR PLANE 3 INPUT-DIP DIRECTION FOR PLANE 3 PRINT" PRINT-ORIENTATION OF FACE: PLANE 4" PRINT" INPUT"DIP FOR PLANE 4 INPUT-DIP DIRECTION FDR PLANE 4 PRINT* UMAX=H*9.810001/6 PRINT USIN6"UMAX ON WEDGE = #*##-;UMAX INPUT-DO YOU WANT TO SPECIFY WATER PRESSURES? Y/N"jAUTDWATf IF AUTOMATON" THEN Ul=U!fiX THEN U2=UMAX "5DIP2 "5DIR2 "iC2 ";PHI2 ";DIP3 •;DIR3 "5DIP4 "5DIR4 IF AUTOWAT*="N" IF AUTOWAT$="N" GOTO 1055 INPUT"U1=? INPUT"U2=? PRINT" INPUT"NETA= INPUT"DO YOU WANT TO STORE DATA IF DAT»='N"GOTO 1095 ELSE GOTO 1064 •{Ul ";U2 "(NETA •;DAT$ 1061 DATA STORAGE SUBROUTINE 1062 ' 111 II 11 I I 111 it 11 it 11 tt 111 t i I I m 11 tt it n t i tt 111 i t 111111111111 t i 11 M 11 H H 1063 'THIS SUBROUTINE STORES ALL INPUT DATA IN A FILE FOR FUTURE ACCESS. 1064 CLS 1065 LOCATE 10,10 1066 PRINT USING "CURRENT DATA FILE = \ \';DATFILE$ 1067 LOCATE 12,19 1068 INPUT"NAME OF STORAGE FILE IF NEW? ELSE HIT RETURN":DATFILE2$ 1069 IF LEN(DATFILE2$) 00 THEN DATFILEi=DATFILE2J 217 1078 OPEN 'OMUDflTFILEI 1071 WRITE ll,6flmRDiH 1073 URITE il,DIPl,DIRl,Cl.PHIl 1073 WRITE »1,DIP2,DIR2,C2,PHI2 107* WRITE #1,DIP3,DIR3,DIP4,DIR4 1075 WRITE #1, Ul.US, NETfl 1076 CLOSE #1 1077 IF SUBFLPG3=1 THEN RETURN 107B GOTO nea 1079 ' 1080 1 I It I I M l 11 H I I I M M H i l l I M l It I I M I I H I M I It I H I ' I I' II M i l l t t M H M M M M 1031 ' DATA RtTREIVPL SUBROUTINE ll?fl2 ' M It I I I H I It H I H H It H 11 H H M It M M M M t H H I H I ++++-H-H-H+++ -H-t-f I I M M 1083 'THIS SUBROUTINE RETREIVES ALL INPUT DATA FROM A STORAGE FILE. 1084 CLS 1085 LOCATE 10,10 10B6 INPUT"NAME OF FILE IN WHICH DATA IS STORED";DATF!LE$ 1087 OPEN "r,#l,DATFILE$ 1088 INPUT fl.SAMMAD.H 1089 INPUT I1.DIP1.DIR1.C1.PHI1 1090 INPUT *1,DIP2,DIR2,C2,PHI2 1091 INPUT il,DIP3,DIR3,DIP4,DIR4 1092 INPUT tl,Ul,U2,NETA 1093 CLGSE #1 1094 GOTO 1102 1095 ' 1096 ' < l ' M M I I I I I I I H I I I H I I I M 11 I I H t l t l l l t i l l II II1 It II M I I I I I H H t l l l M H H I 1097 j • DATA ECHO AND CORRECTION SUBROUTINE 1099 'THIS SUBROUTINE PRINTS ALL DATA THAT WILL BE USED IN ANALYSIS ON SCREEN. 1108 'A PROVISION IS HADE TO CORRECT ALL DATA. 1101 ' 1102 CLS 1103 PRINT" INPUT PARAMETERS 1104 PRINT" 1105 PRINT USING " I. GAMMAD = f### 2. HEIGHT H = ###";GANMAD,H 1186 PRINT" 1107 PRINT USING ' 3. DIP 1 = ## 4. DIP DIRECTION 1 = #t#";DIPl,DIRl 1108 PRINT USING " 5. DIP 2 = tt 6. DIP DIRECTION 2 = *#f";DIP2,DIR2 1109 PRINT USIN6 " 7. DIP 3 = ## 8. DIP DIRECTION 3 = ###";0IP3,DIR3 1110 PRINT USING " 9. DIP 4 = #1 10. DIP DIRECTION 4 = ###";DIP4,DIR4 1111 PRINT" 1112 PRINT USING "11. COHESION 1 = #t#t 12. PHI 1 = ##";C1,PHI1 1113 PRINT USING "13. COHESION 2 » tttt 14. PHI 2 - t#"?C2,PHI2 1114 PRINT" 1115 PRINT USING "15. Ul = #### 16. U2 = ##";U1,U2 1116 PRINT" 1117 INPUT"INDICATE PARAMETER TO BE CHANGED! IF ALL OK ENTER 0!";CHANGE U1B IF CHANGED THEN SUBFLAG3=1 1119 IF CHANGE=0 THEN GTJSUB 1064 1120 IF CHANGED AND PC0N*="Y" THEN GOSUB 1301 1121 IF CHANGED GOTO 11B0 1122 ' 1123 'MAKE ANY DESIRED CHANGES 1124 IF CHANGE=1 GOTO 1140 1125 IF CHANGE=2 GOTO 1142 1126 IF CHANGE=3 GOTO 1144 1127 IF CHANGED GOTO 1152 1128 IF CHANGE=5 GOTO 1146 1129 IF CHANGED GOTO 1154 1139 IF CHANGE=7 GOTO 1148 1131 IF CHANGE=fl GOTO 1156 1132 IF CHAN6E=9 GOTO 1150 1133 IF CHANGE=10 GOTO 1158 1134 IF CHANGED 1 GOTO 1160 1135 IF CHANGE=12 GOTO 1164 1136 IF CHANGE=13 GOTO 1162 1137 IF CHANGE=14 GOTO 1166 1138 IF CHANGE=15 GOTO 1168 1139 IF CHANG£=16 GOTO 1170 218 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 -1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1 H H I M i l I t l l l l t l l H I H I I I M l 11 H I I I ! I M I I I I I I 11 I I I 11 H I I M l t H I I H H I H t INPUT'GAMIWD GOTO 1102 INPUT'H GOTO 1102 INPUTUDIP1 GOTO 1102 INPUT"DIP2 GOTO 1102 INPUT"DIP3 GOTO 1102 INPUT"DIP4 GOTO 1102 INPUT'DIRl GOTO 1102 INPUT"DIR2 GOTO 1102 INPUT"DIR3 GOTO 1102 INPUT°DIR4 GOTO 1102 1 .11 H IDIP1 IDIP2 _• IDIP3 IDIP4 = » iDIRl iDIR2 IDIR3 _ • iOIR4 1 =* ;ci 2 =' _• iPHU = * iPHI2 ;ui ;U2 GOTO 1102 INPUT'COHESION GOTO 1102 INPUT'PHI GOTO 1102 INPUT-PHI GOTO 1102 INPUTUl GOTO 1102 INPUT"U2 GOTO 1102 » ' I I11 I 11 11 M U M I I I M I I I I I I I M M I I I I I M M I H I I M I I M I I I I I I I 11 M l M M M M M ' HflIN CALCULATION SUBROUTINE 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 'THIS SUBROUTINE DOES Ml REQUIRED CALCULATIONS TO COMPUTE FACTOR OF 'SAFETY i 'CONVERT ANGLES TO RADIANS DEGRAD=3.142/1B9 PHI1=DEGRAD*PHI1 PHI2=DE6RAD*PHI2 DIP1=DEGRAD»DIP1 DIP2=DE6RAD*DIP2 DIP3=DEGRAD»DIP3 DIP4=DEGRAD*DIP4 DIR1=DE6RAD*DIR1 DIR2=DEGRAD*DIR2 DIR3=DEGRAD»DIR3 DIR4=DEGRAD»DIR4 IF SENS$="Y" GOTO 1272 'CALCULATE COMPONENTS OF UNIT VECTORS AX=SIN(DIP1)«SIN(DIR1-DIR2) AY=SIN(DIPl)fC0S(DIRl-DIR2) A2=COS(DIPl) FX=SIN(DIP4)«SIN(DIR4-DIR2) FY=SIN(DIP4)fCOS(DIR4-DIR2) F2=COS(DIP4) BY=SIN(DIP2) BZ=COS(DIP2J ' " I=AX*BY 6Z=FX«AY-FY*AX Q=BY»(FZ«AX-FXtAZ)+BZ*GZ 1205 'CHECK IF GEOMETRY ACTUALLY FORMS A WEDGE 1£06 IF NETA*I/G)0 THEN FLAG=-1 1207 IF NETA*(FZ-Q/I)*TAN(DIP3))S0R(1-FZA2) THEN CHECK*-1 1208 IF DIR3=DIR4+(1-NETA)»3.1416/2 AND CHECK=-1 THEN FLAG=-1 1209 IF FLAG 0-1 GOTO 1215 219 1218 CLS 1211 LOCATE 10,1 1212 PRINT" NO WEDGE FORMED WITH INPUT GEOMETRY" 1213 SOUND 100,10 121* STOP 1215 R=AY»BY-tflZ*BZ 1216 K=1-FT2 1217 L=<6RMKAD*H*G)/<3t6Z) 121B P=-8Y*FX/6Z 1219 Nl=<(L/K)*(AZ-R«BZ)-P*Ul)»P/ABS(P) 1220 N2=((L/K)»(BZ-R«AZ)-U2) 1221 M1=(L«AZ-R«U2-P«U1)*P/RBS(P) 1222 M2=(L*BZ-R«P«U1-U2) 1223 ' 1224 'EVALUATE WHETHER SLIDING ON ONE OR BOTH PLANES AND COMPUTE APPROPRIATE 1225 'F.O.S. 1226 ' 1227 'CONTACT IS ON BOTH PLANES: CFLAG=3 122B IF N1)0 AND N2>0 GOTO 1229 ELSE GOTO 1233 1229 F=(Nl*TflN(PHIl)+N2*TAN(PHI2)+ABS(P)»Cl+C2)«SQR«K)/ABS(L«I) 1230 CFLAG=3 1231 GOTO 1252 1232 ' 1233 'CONTACT IS ON PLANE 1: CFLAG=1 1234 IF N2<0 AND H1>0 THEN GOTO 1235 ELSE GOTO 1241 1235 F=M1*TAN(PHI1)+ABS(P)*C1 1236 F=f/SOR(LA2*(l-AZA2)+KMJ2A2+2*(RiAZ-BZ)*L«U2) 1237 CFLAG=1 123B SOTO 1252 1239 ' 1240 'CONTACT IS ON PLANE 2: CFLAG=2 1241 IF NK0 AND K2)0 THEN GOTO 1242 ELSE GOTO 1244 1242 F=M2«TAN(PHI2)+C2 1243 F=F/SQR (LA2*BYA2+KtPA2fUr2+2» (R*BZ-AZ) «P»L«U1) 1244 CFLAG=2 1245 GOTO 1252 1246 ' 1247 'WEDGE IS FLOATED DUE TO WATER PRESSURE CONTACT IS LOST 1248 IF MK0 AND K2<0 THEN CFLAG=0 1249 F=0 1250 ' 1251 'PRINT RESULTS OF ANALYSIS 1252 rrl(0)="WEDGE FLOATED DUE TO PORE PRESSURES" 1253 H$U)="CONTACT ON PLANE 1 ONLY" 1254 H$<2)="C0NTACT ON PLANE 2 ONLY" 1255 H$(3)="C0NTACT ON BOTH PLANES" 1256 IF SUBFLAG2=1 THEN RETURN 1257 CLS 1258 LOCATE 19,19 1259 PRINT USING "\ \ F.O.S = ti.#**";«<CFLAG),F 1260 IF PCON$()"Y" THEN GOTO 1262 1261 LPRINT USING "\ \ F.O.S = tt.t##";H$(CFLA6),F 1262 STOP 1263 END 1264 ' 1265 ' M t t t t i t t i i m n i m n n t n n n m t m t t i m n n m n n n m m i m t m i i 1266 ' SENSITIVITY STUDY SUBROUTINE 1267 1 III l i t I M M H I 1 1 1 H m t i m t H t H I H I 11 I M I I M 1111 M U t l H U I H 111 11 I t i l l 1268 'THIS SUBROUTINE IS ONLY ACTIVATED IF THE INFLUENCE OF C AND PHI ON 1269 'WEDGE STABILITY IS DESIRED. 1270 ' 1271 'INPUT LIMITS DN C AND PHI 1272 INPUT'DO YOU WANT TO SPECIFY C AND PHI RANGE? Y/N";SPEC$ 1273 IF SPEC$="Y" THEN GOTO 1276 1274 CLOW=«:OELTAC=2:CINC=10 1275 PHILOW=20:DELTAPHI=2:PHIINC=15 1276 GOTO 1281 1277 INPUTDCLOW, DELTA C, NUMBER OF INCRO^NTS ";CLOW,DELTPC,CINC 1278 INPUT'PHILOW, DELTA PHI, NUMBER OF INCREMENTS ";PHILDU,DELTAPHI,PHIINC 1279 ' 220 TZZ . i .+((II)3)$UIS+. .=$H03 6VET 3NI3 o i 0=11 nod BVET IHd SnOIhtM ONO NOIS3H03 1N3UU03 UQd Ai3dHS dO MDiDOd INIdd i 2VEI $H30Nn INIUdl 9V£! (.-.4Hiaiin)$SNiMis+. »=«3aNn svn eH(H3NIIHd)*9=Hiaim WT $NI1 IMHdl EVE! r 1X3N 3VH $IHdHNIT=iNn 1VEI $IHd+<abd)*330dS=$IHd 0VEI ($IHd)N3>9=<lbd 6ETI <<f)IHd)*UlS=*IHd 8EE1 DNiHd 01 e=r uod 2ETI . NOIS3HO0 ,=*NI1 9££I •SnSNU N0I13IHd.4(0V)8bT INIUdl SJtl (63)$UH3 INIUdl N3H1 6<3NIIHd i l VEEI .A i iWS dO MQlOUd dO 31801 .INIUdl EEEI mtni Nunxo 3T9NU NQIUIHJ lNiudi m\ . IEEI HHINIUd 3NI1. EE! SHI NO IHd (Nd 3 SDOIUUA MOd *S'0'd dO 31801 0 SINIUd SNIinOUaflS SIHl i 63FT i n i i i i i H i i i i i H i i t H i i i i i H i i i i i i i i m i i H i i n n i i i i i i n n i n i n i i H W i Bet I 3Nimo)iens simsBti AIIAIIISGS INIM . 23:1 III I I I H I I H i t H H H I I H I I t ) 1 1 I I I I t I I I I t H I t i l l I I 1 1 1 1 1 1 1 I I t i l l 1 1 l l l l 1 1 I I I | 93£t i S3E! NMfU3b VcSI .INIUdl ESEI an *9i #### = in 'si . 9Nisn iNiadi ZSEI •lNIMdl I2EI 2 IHd "VI Ht t = 2 N0IS3H03 T I . 9NISn INIUdl 03EI I IHd 'SI Ht t > I N0IS3HO3 ' I I . 9NI5H INIUdl filEI 32EI 01O9 .A.=SSN3S dl 8IEI .INIUdl 21EI cTinns.tt = 2!Hd4334..tt = IIHdM3i .H = vuia4vdias.t#t - V N0I133Hia dia •01 t* = V dia '6 . 9NI5H INIUdl 9IEI £HiaTdIQ!.»## = Z N0U33Uia did •9 tt - £ dia •I . SNISn lNIHdl S K I 2iiia'2diai.### = 3 N0I133Uia dia '9 t« - i dia •9 . 9NISn INIUdl VIET iaialidiai.##i = i Noii33Hia dia •v tt = i dia 1 . SNI5T1 INIUdl EIEI •INIUdl 2IEI H'QbWUSi.ttl - H 1H9I3H "2 tt#t - •I . 9NIST1 INIUdl I IEI SH3J3WUbd lfUNI .INIUdl 0IEI •INIUdl 60EI 021 INIUdl HiaiH B8EI (e!)WH3M0I)$UH3 INIUdl 20TI , .lNIHdl 9«£I .SISATONO A i l l l Sb iS 39031 1U0HS .INIUdl S0CI 'HBlNIUd 3NI1 3Hi NO WOO lfldNI TTO SiNIUd 3NI1IT0B SIHl i V & ! M t t i t t n t i t i i n i t i i n i t i n i i i i t H t n i t n i t n n i n n t t n i n n i t i i i i i i n n t t £0EI SNiinousns aioa IIMNI lNiud o r a 12m n i n t t i t t n t n 1 1 1 n 1 1 1 1 1 1 m i n t t t n n n 1 1 1 1 1 1 1 1 n i n n n i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I0£t i 0N3 663! EETT 8nS09 8621 II 1X3N 2621 dMniHd'dDOT'IIi . tt ' t f t«#t t»#t r 1X3N 9  It tt . 9 I I S 1 INIUd N3H1 .A.=$033dS J! £63! d=(f'IDSQd V63! V6ii ansos E K I !=3901danS 2631 UHd=3IHd 1631 atft)93a*(r)IHd=IIHd 0631 IHdbi"Ba*f+fi01IHd=(r)IHd GOBI ONIIHd Oi 0=f HOd 883! 13=(II)3 282! 13=23 982! 3tJil3atII+«010=I3 SB?! II lNIHd N3H1 .N„=*(E3dS dl V83I 3NI3 Oi 0=11 UQd £83! (0340!>SOd'(03)IHd MIC 393! ST3 183! lN0iSNQ3 3 9NI0T0H' IHd HSflOUHi dOOli 083! 1359 PAD=17-LEN(CDH*) 1351 COH*=SPRCE*(PAD)+COH* 1352 LIN*=CDH* •1353 FOR J=0 TO PHI INC 1354 IF FOS(II,J)(.l THEN FGS(II,J)=0! 1355 FOS*=STR*(FOS(II,J)) 1356 D0T=INSTR(F0S*,V)+2 1357 FOS*=L£FT$(FOSt,DOT) 1358 PAD=6-LEN(FOS$) 1359 FOS$=SPACE*(PAD)+FOS$ 1369 LIN*=UN$+FOSt 1361 NEXT J 1362 LPRINT LIN$ 1363 NEXT II 1364 ' 1365 'PRINT FAILURE MECHANISM 1366 LPRINT CHR*(30) 1367 H$(9)='WED6E FLOATED DUE TO PORE PRESSURES" 1368 H$(l)=aCONTACT ON PLANE 1 ONLY" 1369 H$(2)="CONTACT ON PLANE 2 O.NLY" 1379 H$(3)="C0NTACT ON BOTH PLANES* 1371 LPRINT USINB" \ \"JH$(CFLAS) lo/2 1 1373 'PRINT STRESS CONDITIONS ON FAILURE SURFACES 1374 IF CFLPG=1 THEN LPRINT USING" TOTAL STRESS ON PLANE 1 = tMt .M "!M1 1375 IF CFLAG=2 THEN LPRINT USING" TOTAL STRESS ON PLANE 2 = ####.## ":M2 J76 It CFLAG=3 THEN LPRINT USING" TOTAL STRESS ON PLANE 1 = #i»t.«# *;N1 1377 IF CFLAG=3 THEN LPRINT USIN6" TOTAL STRESS ON PLANE 2 - ttM.tt » N2 1378 U«AX=H«9.810091/6 1379 WRATI0=(Ul+U2)/2/UMAX 1389 LPRINT USING " HATER PRESSURE RATIO U/UMAX = ####.##"5WRATIO 1381 SOUND 109,19 1382 CLS 1383 INPUT'ANALYSIS TITLE-JTITLEI 1384 LPRINT 1385 A$=* . \ \» 1386 LPRINT USING fi$5TITLE* 1387 LPRINT CHR$(12) 1388 RETURN 1389 • 222 BERM FAILURE BACK ANALYSIS A . LOCATION: PIT: BENCH: WALL: DOMAIN: FAILURE MODE: MNZN ULT 1320 EAST NORTHING: EASTING: ELEVATION: D2 PLANE + LATERAL RELEASE B. ORIENTATION: PLANE 1 DIP: DIP DIR: 56 243 PLANE 2 DIP: DIP DIR: 90 323 PLANE 3(CREST) DIP: 0_ DIP DIR: 270 PLANE 4(FACE) 70 DIP: DIP DIR: 270 C. DIMENSIONS: WIDTH ALONG CREST: LENGTH INTERSECTION: 12.0 20.0 HEIGHT TOE/CREST: ESTIMATED VOLUME: 15.0 D. GEOLOGY: PLANE 1 DISCONTINUITY TYPE: ROUGHNESS ANGLE: GOUGE TYPE: WATER CODE: ROCK TYPE: MJ NONE PLANE 2 DISCONTINUITY TYPE: ROUGHNESS ANGLE: GOUGE TYPE: WATER CODE: SR 10 2 cm. GBR E . SKETCH: DATE: 85/08/28 RECORDED BY: TS / JM FAILURE NUMBER: 223 SHORT WEDGE S T A B I L I T Y A N A L Y S I S I N P U T P A R A M E T E R S 1. GAMMAD 3 4 H E I G H T H 1 5 3 . D I P 1 = 5 6 4 . D I P D I R E C T I O N 1 = £43 5 . D I P £ = '. 9 8 6 . D I P D I R E C T I O N £ = 3£3 7 . D I P 3 SS 0 8 . D I P D I R E C T I O N 3 = £70 9 . D I P 4 = 7 0 1 0 . D I P D I R E C T I O N 4 = £70 5 . U l 0 1 6 . U£ = 0 T A B L E OF F A C T O R OF S A F E T Y FRICTION ANGLES IKESION 28 23 26 29 32 35 38 41 44 47 58 8 ! .24 .28 .32 .37 .42 .47 .52 .58 .65 .72 .80 2 ! .32 .36 .48 .44 .49 .54 .60 .66 .72 .79 .87 4 ! .39 .43 .48 .52 .57 .62 .67 .73 .80 .87 .95 & ! .47 .51 .55 .60 .64 .69 .75 .81 .87 .95 1.03 a ; .54 .58 .63 .67 .72 .77 .83 .88 .95 1.02 1.10 19 ! .62 .66 .78 .75 .80 .85 .98 .96 1.83 1.10 1.18 12 ! .70 .74 .78 .82 .87 .92 .98 1.04 1.10 1.17 1.25 14 i .77 .81 .85 .90 .95 1.00 1.85 1.11 1.18 1.25 1.33 16 ! .85 .89 .93 .98 1.02 1.87 1.13 1.19 1.25 1.33 1.41 18 ! .92 .96 1.01 1.85 1.10 1.15 1.20 1.26 1.33 1.40 1.48 28 ! 1.80 1.84 1.88 1.13 1.17 1.23 1.28 1.34 1.40 1.48 1.56 C O N T A C T ON P L A N E 1 ONLY T O T A L S T R E S S ON P L A N E 1 = 3 7 . 7 3 WATER P R E S S U R E R A T I O U /UMAX = 0 . 0 0 WEDGE 1 - DRY C O N D I T I O N SHORT WEDGE STABILITY ANALYSIS INPUT PARAMETERS 1. GAMMAD = 34 o c • HEIGHT H = 15 3. DIP 1 56 4. DIP DIRECTION 1 = £43 5. DIP £ = 90 6. DIP DIRECTION c = 3£3 7. DIP 3 = 0 8. DIP DIRECTION 3 = £70 9. DIP 4 70 10. DIP DIRECTION 4 = £70 5. Ui 13 16. U2 = 13 TABLE OF FACTOR OF SAFETY FRICTION ANGLES ISION 28 23 26 29 32 35 38 41 44 47 58 8 ! 8 8 8 8 8 8 .11 .12 .13 .15 .16 2 ! .12 .13 .14 .15 .16 .17 .18 .19 .28 .22 .24 4 i .19 .28 .21 .22 .23 .24 .25 .26 .28 .29 .31 6 ! .26 .27 .28 .29 .38 .31 .32 .33 .35 .36 .38 8 ! .34 .34 .35 .36 .37 .38 .39 .41 .42 .44 .45 ie ! .41 .42 .43 .44 .45 .46 .47 .48 .49 .51 .53 12 ! .48 .49 .58 .51 .52 .53 .54 .55 .57 .58 .68 14 ! .55 .56 .57 .58 .59 .68 .61 .62 .64 .65 .67 16 ! .63 .63 .64 .65 .66 .67 .68 .78 .71 .73 .74 18 ! .78 .71 .72 .72 .73 .75 .76 .77 .78 .80 .81 28 ! .77 .78 .79 .88 .81 .62 .83 .84 .86 .87 .89 CONTACT ON PLANE 1 ONLY TOTAL STRESS ON PLANE 1 = 8.£8 WATER PRESSURE RATIO U/UMAX = 0.53 WEDGE 1 - WITH WATER - NORMAL RANGE OF C AND PHI SHORT WEDGE S T A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD 3. DIP 1 5. DIP £ 7. DIP 3 9. DIP 4 15. U l 34 56 90 0 70 HEIGHT H = i : 4. 6. 8. 10. DIP DIP DIP DIP DIRECTION DIRECTION DIRECTION DIRECTION 1 = 4 = 13 16. U £ TABLE OF FACTOR OF SAFETY FRICTION ANGLES £ 4 3 3 £ 3 £ 7 0 £ 7 0 = 13 1HESI0N 38 33 36 39 42 45 48 51 54 57 68 18 ! .44 .45 .46 .47 .48 .50 .51 .53 .55 .57 .68 12 ! .51 .52 .53 .54 .56 .57 .59 .68 .62 .65 .67 14 ! .58 .59 .68 .62 .63 .64 .66 .68 .78 .72 .75 16 ! m £6 .67 .68 .69 .70 .72 .73 .75 .77 .79 .82 18 ! .73 .74 .75 .76 .77 .79 .88 .82 .84 .86 .89 28 ! .88 .81 .82 .83 .85 .86 .88 .89 .91 .94 .96 22 i .87 .88 .89 .91 .92 .93 .95 .97 .99 1.81 1.04 24 ! .95 .96 .97 .98 .99 1.00 1.82 1.84 1.86 1.88 1.11 26 ! 1.82 1.83 1.84 1.85 1.86 1.8B 1.89 1.11 1.13 1.15 1.18 28 ! 1.89 1.18 1.11 1.12 1.14 1.15 1.17 1.18 1.28 1.23 1.25 38 ! 1.16 1.17 1.18 1.28 1.21 1.22 1.24 1.26 1.28 1.38 1.33 CONTACT ON PLANE 1 ONLY TOTAL STRESS ON PLANE 1 = 8.£8 WATER PRESSURE RATIO U/UMAX = 0.53 WEDGE 1 - WITH WATER - HIGH LEVELS OF C AND PHI BERM FAILURE BACK ANALYSIS A. LOCATION: PIT: BENCH: WALL: DOMAIN: MNZN ULT 1340 EAST NORTHING: EASTING: ELEVATION: D2 FAILURE MODE: WEDGE, MOSTLY SLIDING ON PLANE 1. B. ORIENTATION: PLANE 1 DIP: 43 DIP DIR: 227 PLANE 2 DIP: 81 DIP DIR: 343 PLANE 3(CREST) DIP: 0 DIP DIR: 270 PLANE 4(FACE) DIP: 70 DIP DIR: 270 C. DIMENSIONS: WIDTH ALONG CREST: 12.0 LENGTH INTERSECTION: 25.0 HEIGHT TOE/CREST: ESTIMATED VOLUME: 16.0 D. GEOLOGY: PLANE 1 DISCONTINUITY TYPE: ROUGHNESS ANGLE: GOUGE TYPE: WATER CODE: ROCK TYPE: MJ NONE PLANE 2 DISCONTINUITY TYPE: JN ROUGHNESS ANGLE: _3 GOUGE TYPE: NONE WATER CODE: 2 GBR E. SKETCH: DATE: 84/08/28 RECORDED BY: TS /JM 227 FAILURE NUMBER: 2 SHORT WEDGE S T A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD 34 HEIGHT H = 16 3. DIP 1 5. DIP £ 7. DIP 3 9. DIP 4 43 4. DIP DIRECTION 1 = £ £ 7 81 6. DIP DIRECTION £ = 343 0 8. DIP DIRECTION 3 = £ 7 0 70 10. DIP DIRECTION 4 = £ 7 0 15. U l 0 16. U£ 0 TABLE OF FACTOR OF SAFETY COHESION 20 22 24 26 FRICTION ANGLES 2B 30 32 34 36 3B 40 0 2 4 6 8 18 12 14 16 18 .64 .68 .73 .78 .82 .87 .91 .96 1.01 1.05 1.10 .71 .75 • B9 .85 .89 .94 .99 1.03 1.88 1.12 1.17 .78 .83 .87 .92 .97 1.81 1.86 1.18 1.15 1.28 1.24 .85 .93 .95 .99 1.84 1.89 1.13 1.18 1.23 1.27 1.32 1.82 1.87 1.12 1.16 1.21 1.26 1.30 1.35 1.48 1.81 1.86 1.18 1.15 1.28 1.24 1.29 1.34 1.38 1.43 1.48 1.18 1.14 1.19 1.23 1.28 1.33 1.37 1.42 1.47 1.51 1.56 1.18 1.23 1.28 1.32 1.37 1.42 1.46 1.51 1.55 1.68 1.65 1.27 1.32 1.37 1.41 1.46 1.51 1.55 1.60 1.65 1.69 1.74 1.37 1.42 1.46 1.51 1.56 1.60 1.65 1.70 1.74 1.79 1.84 1.47 1.52 1.57 1.61 1.66 1.71 1.75 1.B8 1.84 1.89 1.94 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 166.30 TOTAL STRESS ON PLANE £ = 63. ££ WATER PRESSURE RATIO U/UMAX = 0.00 WEDGE £ - DRY CONDITION SHORT WEDGE S T A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD — 34 2. HEIGHT H = 3. DIP 1 43 4. DIP DIRECTION 1 = 5. DIP £ = 81 6. DIP DIRECTION 2 = 7. DIP 3 0 8. DIP DIRECTION 3 = 9. DIP 4 = 70 10. DIP DIRECTION 4 = 15. U l zz 13 16. U£ 16 £ 2 7 343 270 270 13 TABLE OF FACTOR OF SAFETY FRICTION fiNGLES SION 28 22 24 26 28 38 32 34 36 38 48 8 ! .53 .58 .64 .71 .77 .84 .91 .98 1.85 1.13 1.22 2 ! .57 .63 .69 .75 .82 .88 .95 1.03 1.18 1.18 1.27 4 ! .62 .68 .74 .88 .86 .93 1.00 1.07 1.15 1.23 1.31 6 ! .67 .72 .78 .85 .91 .98 1.05 1.12 1.19 1.27 1.36 S ! .71 .77 .83 .89 .96 1.82 1.09 1.16 1.24 1.32 1.41 18 ! .76 .82 .88 .94 1.88 1.87 1.14 1.21 1.29 1.37 1.45 12 i .88 .86 .92 .99 1.85 1.12 1.19 1.26 1.33 1.41 1.58 14 i .85 .91 .97 1.83 1.18 1.16 1.23 1.38 1.38 1.46 1.54 16 ! .98 .96 1.82 1.88 1.14 1.21 1.28 1.35 1.43 1.51 1.59 18 ! .94 1.88 1.86 1.12 1.19 1.26 1.33 1.48 1.47 1.55 1.64 28 ! .99 1.85 1.11 1.17 1.24 1.30 1.37 1.44 1.52 1.68 1.68 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 139.90 TOTAL STRESS ON PLANE 2 = 50.22 WATER PRESSURE RATIO U/UMAX = 0.50 WEDGE 2 - WITH WATER - NORMAL RANGE OF C AND PHI 229 BERM FAILURE BACK ANALYSIS A. LOCATION: PIT: BENCH: WALL: DOMAIN: FAILURE MODE: B. ORIENTATION: MNZN ULT 1340 EAST D2 WEDGE NORTHING: EASTING: ELEVATION: PLANE 1 DIP: DIP DIR: 62 236 PLANE 2 DIP: DIP DIR: PLANE 3(CREST) 84 DIP: .0 352 DIP DIR: 270 PLANE 4(FACE) DIP: 70 DIP DIR: 270 C. DIMENSIONS: WIDTH ALONG CREST: LENGTH INTERSECTION: 8.0 25.0 HEIGHT TOE/CREST: ESTIMATED VOLUME: 17.0 D. GEOLOGY: PLANE 1 DISCONTINUITY TYPE: ROUGHNESS ANGLE: GOUGE TYPE: WATER CODE: ROCK TYPE: E. SKETCH: MJ NONE GBR PLANE 2 DISCONTINUITY TYPE: ROUGHNESS ANGLE: GOUGE TYPE: WATER CODE: MJ NONE DATE: 85/08/28 RECORDED BY: TS / JM FAILURE NUMBER: 230 SHORT WEDGE STABILITY ANALYSIS INPUT PARAMETERS 1. GAMMAD zr 34 £. HEIGHT H = 17 3. DIP 1 = 6£ 4. DIP DIRECTION 1 = £36 5. DIP £ = 84 6. DIP DIRECTION £ = 35£ 7. DIP 3 = 0 8. DIP DIRECTION 3 = £70 9. DIP 4 — 70 10. DIP DIRECTION 4 = £70 5. U l 0 16. U£ 0 TABLE OF FACTOR OF SAFETY FRICTION ANGLES SION 28 22 24 26 28 38 32 34 36 38 40 8 ! .37 .41 .45 .58 .54 .59 .64 .69 .74 88 .86 2 ! .45 .49 .54 .58 .62 .67 .72 .77 .83 88 .94 4 ! .53 .57 .62 .66 .71 .75 .88 .85 .91 % 1.82 6 ! .61 .65 .70 .74 .79 .83 .88 .93 .99 1. 04 1.18 fi ! .69 .73 .78 .82 .87 .91 .96 1.81 1.87 1. 12 1.18 18 ! .77 .82 .86 .98 .95 .99 1.84 1.09 1.15 1. 20 1.26 12 ! .86 .98 .94 .98 1.83 1.88 1.12 1.18 1.23 1. 29 1.35 1* ! .94 .98 1.82 1.86 1.11 1.16 1.21 1.26 1.31 1. 37 1.43 18 ! 1.82 1.86 1.10 1.14 1.19 1.24 1.29 1.34 1.39 1. 45 1.51 18 ! 1.18 1.14 1.18 1.23 1.27 1.32 1.37 1.42 1.47 1. 53 1.59 28 ! 1.18 1.22 1.26 1.31 1.35 1.40 1.45 1.50 1.55 1 61 1.67 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 50. £9 TOTAL STRESS ON PLANE £ = £6.14 WATER PRESSURE RATIO U/UMAX = 0.00 WEDGE 3 - DRY CONDITION - NORMAL RANGE OF C AND PH SHORT WEDGE STABILITY ANALYSIS INPUT PARAMETERS 1. GAMMAD 3. DIP 1 5. DIP £ 7. DIP 9. DIP 15. U l 3 4 34 G£ 84 0 70 £. 4. 8. 8. 10. HEIGHT H = 17 DIP DIP DIP DIP DIRECTION DIRECTION DIRECTION DIRECTION 1 = £ = 3 = 4 = 0 16. U£ TABLE OF FACTOR OF SAFETY FRICTION ANGLES £36 35£ £70 £70 0 SION 38 32 34 36 38 48 42 44 46 48. 58 8 ! .59 .64 .69 .74 88 86 92 .99 1.86 1.14 1.22 1 ! .83 .68 .73 .78 84 98 96 1.83 1.18 1.18 1.26 2 ! .67 .72 .77 .83 88 94 1. 88 1.87 1.14 1.22 1.31 3 ! .71 .76 .81 .87 92 98 1. 85 1.11 1.18 1.26 1.35 4 • .75 .88 .85 .91 96 1. 82 1 89 1.15 1.22 1.38 1.39 5 ! .79 .84 .89 .95 1. 88 1. 86 1. 13 1.19 1.27 1.34 1.43 6 ! .83 .88 .93 .99 1. 84 1. 18 1 17 1.23 1.31 1.38 1.47 7 ! .87 .92 .97 1.83 1. 88 1. 14 1. 21 1.27 1.35 1.42 1.51 8 ! .91 .96 1.81 1.87 1. 12 1. 18 1. 25 1.31 1.39 1.46 1.55 9 ! .95 1.88 1.85 1.11 1 16 1. 22 1 29 1.35 1.43 1.58 1.59 18 ! .99 1.84 1.89 1.15 1 28 1. 26 1. 33 1.48 1.47 1.54 1.63 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 5 3 . £ 9 TOTAL STRESS ON PLANE £ = £ 6 . 1 4 WATER PRESSURE RATIO U/UMAX = 0.00 WEDGE 3 - DRY CONDITION - EXTENDED RANGE OF C AND PHI 0"JO C o d SHORT WEDGE ST A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD = 34 £. HEIGHT H = 17 3. DIP 1 = 62 4. DIP DIRECTION 1 = £ 3 6 5. DIP 2 = 84 6. DIP DIRECTION £ = 3 5 £ 7. DIP 3 = 0 8. DIP DIRECTION 3 = £ 7 0 9. DIP 4 70 10. DIP DIRECTION 4 = £ 7 0 5. U l — 14 16. U £ = 14 TABLE OF FACTOR OF SAFETY FRICTION ANGLES COHESION 28 22 24 26 28 38 32 34 36 38 48 8 ! .16 .18 .28 .22 .24 .26 .29 .31 .33 • 36 .39 2 ! .25 .26 .28 .38 .32 .34 .37 .39 .41 .44 .47 4 ! .33 .34 .36 .38 .48 .43 .45 .47 • 50 .52 .55 6 ! .41 .43 .44 .46 .49 .51 .53 .55 .58 .60 .63 8 ! .49 .51 .53 .55 .57 .59 .61 .63 .66 .68 .71 18 ! .57 .59 .61 .63 .65 .67 .69 .71 .74 .76 .79 12 ! .65 .67 .69 .71 .73 .75 .77 .79 .82 .84 .87 1* ! .73 .75 .77 .79 .81 .83 .85 .87 .98 .92 .95 16 ! .81 .83 .85 .87 .89 .91 .93 .96 .98 1.01 1.83 18 ! .89 .91 .93 .95' .97 .99 1.81 1.04 1.06 1.09 1.11 28 ! .97 .99 1.81 1.83 1.85 1.87 1.09 1.12 1.14 1.17 1.19 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = £ 2 . 3 7 TOTAL STRESS ON PLANE £ = 12.14 WATER PRESSURE RATIO U/UMAX = 0.50 WEDGE 3 - WITH WATER - NORMAL RANGE OF C AND PHI 233 SHORT WEDGE STABILITY ANALYSIS INPUT PARAMETERS 1. GAMMAD 34 2. HEIGHT H = 17 3. DIP 1 = 62 4. DIP DIRECTION 1 = £36 5. DIP 2 84 6. DIP DIRECTION 2 = 352 7. DIP 3 = 0 8. DIP DIRECTION 3 = £70 9. DIP 4 70 10. DIP DIRECTION 4 = £70 L5. U l = 14 16. U2 = 14 TABLE OF FACTOR OF SAFETY FRICTION ANGLES COHESION 38 33 36 39 42 45 48 51 54 57 68 8 ! .28 .38 .33 .37 .41 .46 .51 .57 .64 .71 .88 2 ! .34 .38 .41 .45 .58 .54 .59 .65 .72 .79 .88 4 ! .43 .46 .58 .53 .58 . 62 . 67 .73 .88 .87 .96 6 ! .51 .54 .58 .61 .66 .78 .75 .81 .88 .95 1.84 8 ! .59 .62 .66 .78 .74 .7B .84 .89 .96 1.84 1.13 18 ! .67 .78 .74 .78 .82 .86 .92 .97 1.84 1.12 1.21 12 ! .75 .78 .82 .86 .98 .95 1.88 1.86 1.12 1.28 1.29 14 ! .83 .86 .98 .94 .98 1.83 1.88 1.14 1.28 1.28 1.37 16 ! .91 .94 .98 1.82 1.86 1.11 1.16 1.22 1.28 1.36 1.45 18 ! .99 1.82 1.86 1.18 1.14 1.19 1.24 1.38 1.36 1.44 1.53 28 ! 1.87 1.11 1.14 1.18 1.22 1.27 1.32 1.38 1.44 1.52 1.61 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = ££.37 TOTAL STRESS ON PLANE £ = 1£.14 WATER PRESSURE RATIO U/UMAX = 0.50 WEDGE 3 - WITH WATER - EXTENDED RANGE OF C AND PHI £34 BERM FAILURE BACK ANALYSIS A. LOCATION: PIT: BENCH: WALL: DOMAIN: MNZN ULT 1340 EAST NORTHING: EASTING: ELEVATION: D2 FAILURE MODE: PLANE B. ORIENTATION: PLANE 1 DIP: 34 DIP DIR: 256 PLANE 2 DIP: 256 DIP DIR: 346 PLANE 3(CREST) DIP: 0 DIP DIR: 270 PLANE 4(FACE) DIP: 70 DIP DIR: 270 C. DIMENSIONS: WIDTH ALONG CREST: 10.0 LENGTH INTERSECTION: 25.0 HEIGHT TOE/CREST: ESTIMATED VOLUME: 20.0 D. GEOLOGY: PLANE 1 DISCONTINUITY TYPE: MJ ROUGHNESS ANGLE: 10 GOUGE TYPE: NONE WATER CODE: _ J ROCK TYPE: GBR PLANE 2 DISCONTINUITY TYPE: JN ROUGHNESS ANGLE: _0 GOUGE TYPE: NONE WATER CODE: 1 E. SKETCH: DATE: 85/08/28 RECORDED BY: TS / JM 235 FAILURE NUMBER: 4 SHORT WEDGE S T A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD 34 2. HEIGHT H = 20 3. DIP 1 = 34 4. DIP DIRECTION 1 = 256 5. DIP 2 90 6. DIP DIRECTION 2 = 346 7. DIP 3 = 0 8. DIP DIRECTION 3 = 270 9. DIP 4 = 70 10. DIP DIRECTION 4 = 270 15. U l 0 16. U2 = 0 TABLE OF FACTOR OF SAFETY FRICTION ANGLES SION 28 23 26 29 32 35 38 41 44 47 50 8 ! .53 .62 .72 .82 .92 1.03 1.15 1.28 1.43 1.58 1.76 2 ! .56 .65 .75 .85 .95 1.06 1.18 1.31 1.46 1.61 1.79 4 i .59 .68 .78 .87 .98 1.09 1.21 1.34 1.48 1.64 1.82 6 ! .62 .71 .81 .98 1.81 1.12 1.24 1.37 1.51 1.67 1.85 8 ! .65 .74 .83 .93 1.84 1.15 1.27 1.40 1.54 1.70 1.88 18 ! .68 .77 .86 .96 1.87 1.18 1.30 1.43 1.57 1.73 1.91 12 ! .71 .88 .89 .99 1.18 1.21 1.33 1.46 1.60 1.76 1.94 14 i .74 .83 .92 1.82 1.12 1.24 1.36 1.49 1.63 1.79 1.97 16 ! .77 .86 .95 1.85 1.15 1.27 1.39 1.52 1.66 1.82 1.99 18 ! .88 .89 .98 1.88 1.18 1.29 1.41 1.55 1.69 1.85 2.02 28 ! .82 .91 1.81 1.11 1.21 1.32 1.44 1.57 1.72 1.88 2.05 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 834.48 TOTAL STRESS ON PLANE 2 = 0. 03 WATER PRESSURE RATIO U/UMAX = 0.00 WEDGE 4 DRY CONDITION - NORMAL LEVEL OF C AND PHI 236 SHORT WEDGE STABILITY ANALYSIS INPUT PARAMETERS i . GAMMAD = 34 £. HEIGHT H = £0 3. DIP 1 34 4. DIP DIRECTION 1 = £56 5. DIP £ = 98 6. DIP DIRECTION £ = 346 7. DIP 3 = 0 8. DIP DIRECTION 3 = £70 9. DIP 4 70 10. DIP DIRECTION 4 = £70 15. U l = 16 16. U£ = 16 TABLE OF FACTOR OF SAFETY FRICTION ANGLES COHESION 28 23 26 29 32 35 38 41 44 47 58 8 ! .46 .54 .62 .78 .79 .89 .99 1.11 1.23 1.37 1.52 2 ! .49 .56 .64 .73 .82 .92 1.82 1.13 1.25 1.39 1.54 4 i .51 .59 .67 .75 .84 .94 1.84 1.16 1.28 1.42 1.57 6 ! .54 .61 .69 .78 .87 .97 1.87 1.18 1.31 1.44 1.59 8 ! .56 .64 .72 .81 .98 .99 1.18 1.21 1.33 1.47 1.62 18 ! .59 .66 .75 .83 .92 1.82 1.12 1.23 1.36 1.49 1.65 12 ! .61 .69 .77 .86 .95 1.84 1.15 1.26 1.38 1.52 1.67 14 i .64 .72 .88 .88 .97 1.87 1.17 1.28 1.41 1.54 1.78 16 ! .66 .74 .82 .91 1.88 1.89 1.28 1.31 1.43 1.57 1.72 IB ! .69 .77 .85 .93 1.82 1.12 1.22 1.34 1.46 1.59 1.75 28 ! .71 .79 .87 .96 1.85 1.14 1.25 1.36 1.48 1.62 1.77 CONTACT ON PLANE 1 ONLY TOTAL STRESS ON PLANE 1 = 719.75 WATER PRESSURE RATIO U/UMAX = 0.49 WEDGE 4 - WITH WATER - NORMAL RANGE OF C AND PHI £37 BERM FAILURE BACK ANALYSIS A. LOCATION: PIT: BENCH: WALL: DOMAIN: MNZN ULT 1340 EAST NORTHING: EASTING: ELEVATION: D2 FAILURE MODE: WEDGE B. ORIENTATION: PLANE 1 DIP: 57 DIP DIR: 229 PLANE 2 DIP: 69 DIP DIR: 321 PLANE 3(CREST) DIP: _0 DIP DIR: 270 PLANE 4(FACE) DIP: 70 DIP DIR: 270 C. DIMENSIONS: WIDTH ALONG CREST: LENGTH INTERSECTION: 5.0 7.0 D. GEOLOGY: PLANE 1 DISCONTINUITY TYPE: JN ROUGHNESS ANGLE: _0 GOUGE TYPE: NONE WATER CODE: _2 ROCK TYPE: GBR HEIGHT TOE/CREST: ESTIMATED VOLUME: 15.0 PLANE 2 DISCONTINUITY TYPE: JN ROUGHNESS ANGLE: _7 GOUGE TYPE: NONE WATER CODE: 2 E. SKETCH: DATE: 85/08/28 RECORDED BY: TS / JM 238 FAILURE NUMBER: 5 SHORT WEDGE S T A B I L I T Y ANALYSIS 1. GAMMAD INPUT PARAMETERS 34 2. HEIGHT H 3. DIP 5. DIP 7. 9. DIP DIP 15. U l 57 69 0 73 0 4. 6. 8. 10. DIP DIP DIP DIP DIRECTION DIRECTION DIRECTION DIRECTION 1 2 3 4 16. U2 = 15 = 229 = 321 = 270 = 270 0 TABLE OF FACTOR OF SAFETY FRICTION ANGLES SION 20 23 26 29 32 35 38 41 44 47 58 8 1 .35 .41 .47 .53 .60 • SB 76 84 .94 1.04 1.16 2 ! .41 .47 .53 .60 .67 .74 82 90 1.00 1.10 1.22 4 ! .47 .53 .59 .66 .73 .80 88 % 1.06 1.16 1.28 6 ! .53 .59 .65 .72 .79 .86 94 1 03 1.12 1.22 1.34 8 ! .68 .65 .72 .78 .85 .92 1. 80 1 09 1.18 1.29 1.40 10 ! .66 .72 .78 .84 .91 .98 1 06 1 15 1.24 1.35 1.46 12 i .72 .78 .84 .90 .97 1.05 1. 13 1 21 1.30 1.41 1.52 14 ! .78 .84 .90 .97 1.03 1.11 1. 19 1 27 1.37 1.47 1.59 16 ! .84 .90 .96 1.03 1.10 1.17 1. 25 1 33 1.43 1.53 1.65 18 ! .90 .96 1.02 1.09 1.16 1.23 1. 31 1 40 1.49 1.59 1.71 20 ! .96 1.02 1.88 1.15 1.22 1.29 1 37 1 46 1.55 1.65 1.77 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 47.36 TOTAL STRESS ON PLANE 2 = 26.10 WATER PRESSURE RATIO U/UMAX = 0.00 WEDGE 5 - DRY CONDITION - NORMAL RANGE OF C AND PHI SHORT WEDGE ST A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD 34 HEIGHT H 15 3. DIP 1 5. DIP £ 7. DIP 3 9. DIP 4 57 69 IZI 70 4. 6. 8. 10. DIP DIRECTION 1 = £ £ 9 DIP DIRECTION £ = 3£i DIP DIRECTION 3 = £ 7 0 DIP DIRECTION 4 = £ 7 0 15. U l 12 16. U £ TABLE OF FACTOR OF SAFETY FRICTION ANGLES COHESION 28 23 26 29 32 35 38 41 44 47 58 8 ! .22 .25 .29 .33 .37 .42 .47 .52 .58 .64 . 72 2 i .28 .31 .35 .39 .43 .48 .53 .58 .64 .71 . 78 4 ! .34 .37 .41 .45 .58 .54 .59 .64 .78 .77 84 6 ! .48 .44 .47 .51 .56 .68 .65 .71 .76 .83 . 98 8 ! .46 .58 .54 .58 .62 .66 .71 .77 .83 .89 . % 18 ! .52 .56 .68 .64 .68 .73 .78 .83 .89 .95 1. 82 12 ! .58 .62 .66 .78 .74 .79 .84 .89 .95 1.01 1. 09 14 ! .65 .68 .72 .76 .88 .85 .98 .95 1.01 1.87 1. 15 16 ! .71 .74 .78 .82 .87 .91 .96 1.81 1.87 1.14 1. 21 18 ! .77 .81 .84 .88 .93 .97 1.82 1.87 1.13 1.20 1. 27 28 ! .83 .87 .91 .95 .99 1.83 1.88 1.14 1.19 1.26 1. 33 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 31.54 TOTAL STRESS ON PLANE £ = 14.10 WATER PRESSURE RATIO U/UMAX = 0.49 WEDGE 5 - WITH WATER - NORMAL RANGE OF C AND PHI £40 SHORT WEDGE S T A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD — 34 £. HEIGHT H = 15 3. DIP 1 57 4. DIP DIRECTION 1 = £ £ 9 5. DIP £ = 69 6. DIP DIRECTION £ = 3£1 7. DIP 3 = I7J 8. DIP DIRECTION 3 = £ 7 0 9. DIP 4 = 70 10. DIP DIRECTION 4 = £ 7 0 5. U l = 1£ 16. U£ = 1£ TABLE OF FACTOR OF SAFETY FRICTION ANGLES IHESION 48 42 44 46 48 50 52 54 56 58 60 e ! .58 .54 .58 .62 .67 .72 .77 .83 .89 .96 1.84 2 ! .56 .68 .64 .68 .73 .78 .83 .89 .95 1.03 1.10 4 ! .63 .66 .78 .74 .79 .84 .89 .95 1.82 1.09 1.17 6 ! .69 .72 .76 .81 .85 .90 .95 1.81 1.08 1.15 1.23 8 ! .75 .79 .83 .87 .91 .96 1.82 1.87 1.14 1.21 1.29 18 ! .81 .85 .89 .93 .97 1.82 1.88 1.14 1.20 1.27 1.35 12 ! .87 .91 .95 .99 1.84 1.89 1.14 1.28 1.26 1.33 1.41 14 ! .93 .97 1.81 1.85 1. 10 1.15 1.28 1.26 1.32 1.39 1.47 16 ! .99 1.83 1.87 1.11 1.16 1.21 1.26 1.32 1.38 1.46 1.54 18 ! 1.86 1.89 1.13 1.18 1.22 1.27 1.32 1.38 1.45 1.52 1.60 28 ! 1.12 1.15 1.19 1.24 1.28 1.33 1.38 1.44 1.51 1.58 1.66 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 31.54 TOTAL STRESS ON PLANE 2 = 14.10 WATER PRESSURE RATIO U/UMAX = 0.49 WEDGE 5 - WITH WATER - EXTENDED RANGE OF C AND PHI £41 BERM FAILURE BACK ANALYSIS A. LOCATION: PIT: BENCH: WALL: DOMAIN: MNZN ULT 1340 EAST NORTHING: EASTING: ELEVATION: D2 FAILURE MODE: WEDGE B. ORIENTATION: PLANE 1 DIP: 48 DIP DIR: 276 PLANE 2 DIP: 87 DIP DIR: 341 PLANE 3(CREST) DIP: 0 DIP DIR: 290 PLANE 4(FACE) DIP: 70 DIP DIR: 290 C. DIMENSIONS: WIDTH ALONG CREST: 5.0 LENGTH INTERSECTION: 10.0 HEIGHT TOE/CREST: ESTIMATED VOLUME: 8.0 D. GEOLOGY: PLANE 1 DISCONTINUITY TYPE: ROUGHNESS ANGLE: GOUGE TYPE: WATER CODE: ROCK TYPE: JN NONE LAPILLI PLANE 2 DISCONTINUITY TYPE: JN ROUGHNESS ANGLE: _2 GOUGE TYPE: NONE WATER CODE: 2 E. SKETCH: DATE: 85/08/28 RECORDED BY: TS / JM 242 FAILURE NUMBER: 6 SHORT WEDGE ST A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD 34 2. HEIGHT H B 3. 5. 7. 9. DIP DIP DIP DIP 48 87 0 70 4. 6. 8. Ii DIP DIP DIP DIP DIRECTION DIRECTION DIRECTION DIRECTION 15. U l 16. U2 276 341 290 290 0 TABLE OF FACTOR OF SAFETY FRICTION ANGLES ESION 20 23 26 29 32 35 38 41 44 47 58 0 ! .32 .38 .43 .49 .56 .63 .70 .78 .86 .96 1.87 2 ! .48 .46 .52 .58 .64 .71 .78 .86 .95 1.84 1.15 4 ! .48 .54 .60 .66 .72 .79 .86 .94 1.03 1.12 1.23 6 ! .57 .62 .68 .74 .80 .87 .94 1.02 1.11 1.28 1.31 8 ! .65 .70 .76 .82 .88 .95 1.02 1.10 1.19 1.29 1.39 10 ! .73 .78 .84 .90 .96 1.03 1.10 1.18 1.27 1.37 1.47 12 ! .81 * BS .92 .98 1.04 1.11 1.19 1.26 1.35 1.45 1.55 14 ! .89 .95 1.00 1.06 1.13 1.19 1.27 1.35 1.43 1.53 1.64 16 ! .97 1.03 1.08 1.14 1.21 1.27 1.35 1.43 1.51 1.61 1.72 18 ! 1.85 1.11 1.16 1.22 1.29 1.36 1.43 1.51 1.59 1.69 1.88 20 ! 1.13 1.19 1.25 1.31 1.37 1.44 1.51 1.59 1.68 1.77 1.88 CONTACT ON PLANE 1 ONLY TOTAL STRESS ON PLANE 1 = 95.78 WATER PRESSURE RATIO U/UMAX = 0.00 WEDGE 6 - DRY CONDITION - NORMAL RANGE OF C AND PHI 243 SHORT WEDGE S T A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD 34 2. HEIGHT H B 3. DIP 1 5. DIP 2 7. DIP 3 9. DIP 4 48 87 0 70 4. 6. 8. 10. DIP DIRECTION 1 = £ 7 6 DIP DIRECTION 2 = 341 DIP DIRECTION 3 = £ 9 0 DIP DIRECTION 4 = £ 9 0 15. U l 7 16. 7 TABLE OF FACTOR OF SAFETY FRICTION ANGLES COHESION 20 23 26 29 32 35 38 41 44 47 50 1 ! .21 .24 .28 .32 .36 .40 .45 .50 • 56 .62 .69 2 ! .29 .32 .36 • 4d .44 .48 .53 .58 .64 .70 .77 4 i .37 .40 .44 .48 .52 •56 .61 .66 .72 .78 .85 6 ! .45 .48 .52 .56 .60 .64 .69 .74 .80 .86 .93 8 ! .53 •56 .60 .64 .68 .72 .77 .82 .88 .94 1.01 10 ! .61 .64 .68 .72 .76 .80 .85 .90 .96 1.02 1.09 12 ! .69 .72 .76 .80 .84 .88 .93 .98 1.84 1.10 1.17 14 i .77 .80 .84 .88 .92 .96 1.01 1.06 1.12 1.18 1.25 16 ! .84 a 68 .92 .96 1.00 1.04 1.09 1.14 1.20 1.26 1.33 18 ! .92 .96 1.00 1.04 1.08 1.12 1.17 1.22 1.28 1.34 1.41 20 ! 1.00 1.04 1.08 1.12 1.16 1.20 1.25 1.30 1.36 1.42 1.49 CONTACT ON PLANE 1 ONLY TOTAL STRESS ON PLANE 1 = 63. 13 WATER PRESSURE RATIO U/UMAX = 0.54 WEDGE 6 - WITH WATER - NORMAL RANGE OF C AND PHI BERM FAILURE BACK ANALYSIS A. LOCATION: PIT: BENCH: WALL: DOMAIN: FAILURE MODE: B. ORIENTATION: MNZN ULT 1360 EAST D2 WEDGE NORTHING: EASTING: ELEVATION: PLANE 1 DIP: DIP DIR: 38 296 PLANE 2 DIP: DIP DIR: 79 204 PLANE 3(CREST) DIP: 0_ DIP DIR: 270 PLANE 4(FACE) 70 DIP: DIP DIR 270 C. DIMENSIONS: WIDTH ALONG CREST: 3.0 LENGTH INTERSECTION: 2.0 HEIGHT TOE/CREST: ESTIMATED VOLUME: 2.0 D. GEOLOGY: PLANE 1 DISCONTINUITY TYPE: JN ROUGHNESS ANGLE: _3 GOUGE TYPE: NONE WATER CODE: _2 ROCK TYPE: LAPILLI PLANE 2 DISCONTINUITY TYPE: ROUGHNESS ANGLE: GOUGE TYPE: WATER CODE: JN _10 NONE E. SKETCH: DATE: 85/08/28 RECORDED BY: TS / JM 245 FAILURE NUMBER: 7 SHORT WEDGE STABILITY ANALYSIS INPUT PARAMETERS 1. GAMMAD 34 HEIGHT H 3. 5. 7. 9. DIP DIP DIP DIP 15. Ul 38 79 0 70 0 4. DIP DIRECTION 6. DIP DIRECTION 8. DIP DIRECTION 10. DIP DIRECTION 16. U2 1 = £ = 3 = 4 = £96 £04 £70 £70 0 TABLE OF FACTOR OF SAFETY FRICTION ANGLES .SIDN 20 23 26 29 32 35 38 41 44 47 50 0 ! .51 .68 .69 .78 .88 .99 1.11 1.23 1.37 1.52 1.69 2 ! .83 .91 1.80 1.18 1.20 1.31 1.42 1.55 1.68 1.84 2.81 4 ! 1.14 1.23 1.32 1.41 1.51 1.62 1.73 1.86 2.80 2.15 2.32 6 ! 1.45 1.54 1.63 1.73 1.83 1.93 2.05 2.17 2.31 2.46 2.63 8 ! 1.77 1.85 1.94 2.84 2.14 2.25 2.36 2.49 2.63 2.78 2.95 18 ! 2.88 2.17 2.26 2.35 2.45 2.56 2.68 2.88 2.94 3.09 3.26 12 ! 2.48 2.48 2.57 2.67 2.77 2.88 2.99 3.12 3.25 3.48 3.57 14 ! 2.71 2.88 2.89 2.98 3.08 3.19 3.30 3.43 3.57 3.72 3.89 16 ! 3.82 3.11 3.20 3.38 3.40 3.50 3.62 3.74 3.88 4.83 4.28 18 ! 3.34 3.42 3.51 3.61 3.71 3.82 3.93 4.86 4.19 4.35 4.52 28 ! 3.65 3.74 3.83 3.92 4.02 4.13 4.25 4.37 4.51 4.66 4.83 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 = 35.09 TOTAL STRESS ON PLANE £ = 4.09 WATER PRESSURE RATIO U/UMAX = 0.00 WEDGE 7 - DRY CONDITION - NORMAL RANGE OF C AND PHI £46 SHORT WEDBE S T A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD 34 2. HEIGHT H — C 3. DIP 1 = 38 4. DIP DIRECTION 1 = 296 5. DIP 2 79 6. DIP DIRECTION 2 = 204 7. DIP 3 = 0 8. DIP DIRECTION 3 = 270 9. DIP 4 = 70 10. DIP DIRECTION 4 = £ 7 0 15. U l = £ 16. U2 £ TABLE OF FACTOR OF SAFETY FRICTION ANGLES COHESION 28 23 26 29 32 35 38 41 44 47 58 8 < .48 .47 .54 .61 .69 .77 .86 .96 1.07 1.18 1.32 2 ! .71 .78 .85 .92 1.88 1.89 1.18 1.27 1.38 1.58 1.63 4 ! 1.83 1.89 L I E 1.24 1.32 1.48 1.49 1.59 1.69 1.81 1.94 6 ! 1.34 1.41 1.48 1.55 1.63 1.71 1.88 1.90 2.01 2.13 2.26 8 ! 1.65 1.72 1.79 1.87 1.94 2.83 2.12 2.21 2.32 2.44 2.57 10 ! 1.97 2.84 2.11 2.18 2.26 2.34 2.43 2.53 2.64 2.75 2.89 12 ! 2.28 2.35 2.42 2.49 2.57 2.66 2.75 2.84 2.95 3.87 3.28 14 ! 2.68 2.66 2.73 2.81 2.89 2.97 3.86 3.16 3.26 3.38 3.51 16 ! 2.91 2.98 3.85 3.12 3.28 3.28 3.37 3.47 3.58 3.78 3.83 18 ! 3.22 3.29 3.36 3.44 3.51 3.68 3.69 3.78 3.89 4.81 4.14 28 ! 3.54 3.68 3.68 3.75 3.83 3.91 4.80 4.10 4.21 4.32 4.46 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 - £ 8 . 4 5 TOTAL STRESS ON PLANE 2 = 2.09 WATER PRESSURE RATIO U/UMAX = 0.61 WEDGE 7 - WITH WATER - NORMAL RANGE OF C AND PHI £ 4 7 BERM FAILURE BACK ANALYSIS A. LOCATION: PIT: BENCH: WALL: DOMAIN: MNZN ULT 1360 EAST NORTHING: EASTING: ELEVATION: D2 FAILURE MODE: WEDGE B. ORIENTATION: PLANE 1 DIP: 43 DIP DIR: 327 PLANE 2 DIP: 90 DIP DIR: 327 PLANE 3(CREST) DIP: 0_ DIP DIR: 270 PLANE 4(FACE) DIP: 70 DIP DIR: 270 C. DIMENSIONS: WIDTH ALONG CREST: 10.0 HEIGHT TOE/CREST: 10.0 LENGTH INTERSECTION: 15.0 ESTIMATED VOLUME: D. GEOLOGY: PLANE 1 DISCONTINUITY TYPE: MJ ROUGHNESS ANGLE: _3 GOUGE TYPE: NONE WATER CODE: _3 ROCK TYPE: GBR PLANE 2 DISCONTINUITY TYPE: ROUGHNESS ANGLE: GOUGE TYPE: WATER CODE: JN 2 cm. NONE E. SKETCH: DATE: 85/08/28 RECORDED BY: TS / JM 248 FAILURE NUMBER: 8 SHORT WEDGE S T A B I L I T Y ANALYSIS INPUT PARAMETERS 1. GAMMAD = 34 £. HEIGHT H = 10 3. DIP 1 43 4. DIP DIRECTION 1 — £ 3 7 5. DIP £ 90 6. DIP DIRECTION £ = 3 £ 7 7. DIP 3 = 0 a. DIP DIRECTION 3 = £ 7 0 9. DIP 4 = 70 10. DIP DIRECTION 4 = £ 7 0 5. U l — 0 16. U£ = 0 TABLE OF FACTOR OF SAFETY FRICTION ANGLES IKESION 20 23 26 29 32 35 38 41 44 47 50 8 ! .39 .45 .52 .59 .67 .75 .83 .93 1.03 1.15 1.27 2 ! .47 .54 .60 .68 .75 .83 .92 1.01 1.12 1.23 1.36 4 ! • 56 .62 .69 .76 .84 .92 1.00 1.10 1.20 1.32 1.44 6 ! .64 .71 .78 .85 .92 1.00 1.09 1.18 1.29 1.40 1.53 8 ! .73 .79 .86 .93 1.01 1.09 1.18 1.27 1.37 1.49 1.62 10 ! .81 .88 .95 1.02 1.09 1.17 1.26 1.36 1.46 1.57 1.70 12 ! .90 .96 1.03 1.10 1.18 1.26 1.35 1.44 1.55 1.66 1.79 14 ! .99 1.05 1.12 1.19 1.27 1.35 1.43 1.53 1.63 1.75 1.87 16 ! 1.07 1.14 1.20 1.28 1.35 1.43 1.52 1.61 1.72 1.83 1.96 IB ! 1.16 1.22 1.29 1.36 1.44 1.52 1.60 1.70 1.80 1.92 2.04 20 ! 1.24 1.31 1.38 1.45 1.52 1.60 1.69 1.78 1.89 2.00 2.13 CONTACT ON BOTH PLANES TOTAL STRESS ON PLANE 1 • = 81.46 TOTAL STRESS ON PLANE £ = 0.00 WATER PRESSURE RATIO U/UMAX = 0.00 WEDGE 8 - DRY CONDITION - NORMAL RANGE OF C AND PHI £ 4 9 SHORT WEDGE S T A B I L I T Y ANALYSIS INPUT PARAMETERS GAMMAD 34 HEIGHT H = 10 3. DIP 1 5. DIP £ 7. DIP 3 9. DIP 4 43 4. DIP DIRECTION 1 = £ 3 7 90 6. DIP DIRECTION £ = 3 £ 7 0 8. DIP DIRECTION 3 = £ 7 0 70 10. DIP DIRECTION 4 = £ 7 0 15. U l a 16. U £ 8 TABLE OF FACTOR OF SAFETY FRICTION ANGLES :SION 28 23 26 29 32 35 38 41 44 47 58 8 ! .38 .35 .48 .46 .51 .58 .64 .72 .88 .89 .98 2 ! .36 .41 .46 .51 .57 .64 .70 .78 .86 .94 1.84 4 ! .42 .47 .52 .57 .63 .69 .76 .83 .91 1.00 1.10 fi ! .47 .52 .SB .63 .69 .75 .82 .89 .97 1.86 1.16 8 ! .53 .58 .64 .69 .75 .81 .88 .95 1.83 1.12 1.22 18 ! .59 .64 .78 .75 .81 .87 .94 1.81 1.89 1.18 1.28 12 ! .65 .78 .75 .81 .87 .93 1.00 1.87 1.15 1.24 1.34 14 ! .71 .76 .81 .87 .93 .99 1.06 1.13 1.21 1.38 1.40 16 ! .77 .82 .87 .93 .99 1.85 1.12 1.19 1.27 1.36 1.46 18 ! .83 .88 .93 .99 1.85 1.11 1.18 1.25 1.33 1.42 1.52 28 ! .89 .94 .99 1.85 1.18 1.17 1.23 1.31 1.39 1.48 1.58 CONTACT ON PLANE 1 ONLY TOTAL STRESS ON PLANE 1 = 63.40 WATER PRESSURE RATIO U/UMAX = 0.49 WEDGE 8 - WITH WATER - NORMAL RANGE OF C AND PHI APPENDIX D. APPROXIMATE ROCK STRENGTH CLASSIFICATION (chart after Hoek & Bray, 1981) So. Description Uniaxial compressive strength l b / i n 2 kg/cm2 MPa Extutip les SI VERY SOFT SOIL - e a s i l y mou lded w i t h f i n g e r s , shows d i s t i n c t h e e l m a r k s . <S <0.4 <0.04 S2 SOFT SOIL - mou lds w i t h s t r o n g p r e s s u r e f r o m f i n g e r s , shows f a i n t h e e l m a r k s . 5-10 0 .4 -0 .8 0 .04 - 0 .08 S3 FIRM SOIL - v e r y d i f f i c u l t t o mou ld w i t h f i n g e r s , i n d e n t e d w i t h f i n g e r n a i l , d i f f i c u l t t o c u t w i t h hand s p a d e . 10-20 0 .8-1 .5 0 .08 - 0 .15 S4 S T I F F SOIL - c a n n o t be mou lded w i t h f i n g e r s , c a n n o t be c u t w i t h hand s p a d e , r e q u i r e s hand p i c k i n g f o r e x c a v a t i o n . 2 0 - 8 0 1.5-6.0 0 .15 - 0 .60 SS VERY S T I F F SOIL - v e r y t o u g h . d i f f i c u l t t o move w i t h hand p i c k , p n e u m a t i c s p a d e r e q u i r e d f o r e x c a v a t i o n . 8 0 - 1 5 0 6-10 0.6-1.0 Rl VERY WEAK ROCK - c r u m b l e s u n d e r s h a r p b l o w s w i t h g e o l o g i c a l p i c k p o i n t , c a n be c u t w i t h p o c k e t k n i f e . 150-3500 10-250 1-25 C h a l k , r o c k s a l t R2 MODERATELY WEAK ROCK - s h a l l o w c u t s o r s c r a p i n g w i t h p o c k e t k n i f e w i t h d i f f i c u l t y , p i c k p o i n t i n d e n t s d e e p l y w i t h f i r m b l o w . 3500-7500 2 5 0 - 5 0 0 2 5 - 5 0 C o a l , s c h i s t , s i l t s t o n e R3 MODERATELY STRONG ROCK - k n i f e c a n n o t be used to s c r a p e o r p e e l s u r f a c e , s h a l l o w i n d e n t a -t i o n s u n d e r f i r m b low f r o m p i c k p o i n t . 7500-15000 500-1000 50-100 S a n d s t o n e , s l a t e , s h a l e R4 STRONG ROCK - h a n d - h e l d s a m p l e b r e a k s w i t h one f i r m b low f rom hammer end o f g e o l o g i c a l p i c k . 15000-30000 1000-2000 100-200 M a r b l e , g r a n i t e , g n e i s s R5 VERY STRONG ROCK - r e q u i r e s many b lows f rom g e o l o g i c a l p i c k t o b r e a k i n t a c t s a m p l e . > 30000 > 2000 > 200 Q u a r t z i t e , d o l e r i t e , g a b b r o , b a s a l t 251 APPENDIX E E . l FALLING HEAD TEST THEORY Hy d r a u l i c c o n d u c t i v i t i e s can be c a l c u l a t e d from f a l l i n g head t e s t data by s o l v i n g the governing d i f f e r e n t i a l equation. The method, f i r s t i ntroduced by Hvorslev i s presented i n Freeze, 1979. This appendix presents the s o l u t i o n t o the d i f f e r e n t i a l equation used t o determine the h y d r a u l i c c o n d u c t i v i t y c o e f f i c i e n t and the re g r e s s i o n method used t o o b t a i n a r e p r e s e n t a t i v e s e m i l o g a r i t h m i c r e l a t i o n s h i p between excess head and time. Figure A . l d e f i n e s the parameters used i n the t e s t . R O D R A D I U S r jt/ w ni w \ m X T E S T D A T U M A T C O L L A R L - E Q U I L I B R I U M P H R E A T I C S U R F A C E D R I L L H O L E R A D I U S R l T E S T I N T E R V A L The v a r i a b l e s used i n t h i s development are: h w - depth t o water t a b l e m h ( t ) - excess pressure head d r i v i n g flow m h - depth t o e q u i l i b r i u m p h r e a t i c s u r f a c e m L - length o f t e s t s e c t i o n m r - inner r a d i u s of rod m R - r a d i u s o f d r i l l h o l e m q ( t ) - v o l u m e t r i c r a t e of flow i n t o rock mVs F - shape f a c t o r m T - time f a c t o r s K - h y d r a u l i c c o n d u c t i v i t y cm/s 252 The differential equation is obtained by equating rate of flow into the rock and the flow down the rods. q(t) = - i r -r^dh/dt = F-K-h(t) 1. where K = hydraulic conductivity F = shape factor, depends on shape & dimension of test interval. Define basic time lag T c: T 0 = 2. F-K Then substituting 2 into 1. T0-dh/dt = h(t) 3. dh/h = (-1/T0 ) dt 4. and integrating: f h t tt dh/h = (-1/T.) dt 5. > h. ln(h) = (-1/T„ ) (tx - t, ) At t, = 0 h, = h n; therefore: ln(h t - h 0) = (-1/T0) ( t t - 0 ) ln(h 2/h 0) = (-1/T.) t Equation 8 illustrates the semilogarithmic relationship between excess pressure head and time. 253 BOUNDARY CONDITIONS:. Checking v a l i d i t y of equation 8 by e v a l u a t i n g boundary c o n d i t i o n s , at tt= 0 h i = h 0 .*. l n ( h t / h 0 ) = ( - l / T 0 ) - t t = 0 at t X = « K > h a = 0 l n ( h 2 / h 0 ) = (-l/T«,)-ta= - oo DETERMINING T : l n ( h a / h 0 ) = ( - l / T . ) - t ln(0.368) = -1 when h,/ h 0 = 0.368 - t 2 / T 6 = -1 so T can be determined by p l o t t i n g l n ( h 4 / h 0 ) vs. t t and determining the tj _ value at hz = 0.368 h 0 . t» = T e h ( t ) l n d V h , ) DETERMINING K: Hvorslev established an empirical relationship that expresses the shape factor F. This relationship i s valid i f L/R > 8. F = 2*L« tr In(L/R) Substituting in Equation 2: K = r • In(L/R) 2-L-T 254 REGRESSION: A s t r a i g h t l i n e r e l a t i o n s h i p should e x i s t when the f a l l i n g head data i s p l o t t e d on a semi l o g a r i t h m i c graph, ( i . e . ln(ht/h«, ) vs. t j as i t i s governed by Equation 8. The slope of t h i s l i n e w i l l have the value -1/To. By using l i n e a r r e g r e s s i o n t o determine the best values f o r a & b i n the s t r a i g h t l i n e equation y = a + bx the best f i t slope can be e s t a b l i s h e d . The goodness of f i t or " l i n e a r i t y " i s t e s t e d by e v a l u a t i n g the c o e f f i c i e n t of determination R that i s equal t o one f o r p e r f e c t l y l i n e a r data and approaches zero i f the data i s non l i n e a r . The two r e g r e s s i o n equations are: A n + B X = Y A-SXj + B ' K X i 2 ) = I Xi • Yi 11. 12. S o l v i n g 11 f o r A: So l v i n g 12 f o r B: A = l Y i ~ B-IXi 13. n B = pj • Y; - Yi - B-SXj • I X.j J 14. B-n - E ( X i a ) =n>I(X;-Yj) - l Y j - I X ; + B- r» IXj 15. B = n t (Xi - Yi ) - EY,- IX; 16. n - E ( X i l ) - IXJTXJ Equation 16 i s f i r s t s o l v e d f o r B, then equation 13 i s solved f o r A. F i n a l l y , the r e g r e s s i o n c o e f f i c i e n t R i s c a l c u l a t e d by: R 4 = A l Y ; + B-S(X; - Yi. ) - 1/n (£Yi f (Yv* ) - l / n - ( l Y . ) * 255 APPENDIX F. PROGRAM EQFHEAD F.l OBJECTIVE Program EQFHEAD was developed to evaluate f a l l i n g head test data and determine the coefficient of hydraulic conductivity. The most time consuming portion of the f a l l i n g head test analysis is constructing a semilogarithmic plot of excess head vs. time. A linear regression subroutine was incorporated into the program to eliminate the need for construction of the plot. F.2 THEORY The program uses linear regression to find a best f i t t i n g straight line through the data points. The equations that are used in the regression are presented in Appendix E. The goodness of f i t of the data to a straight line is quantitatively expressed in terms of the coefficient of determination. This parameter varies between 0 and 1, the latter being a perfect f i t . Data that has a coefficient value between 0.9 and 1.0 can be considered sufficiently linear to be used for the analysis. If the coefficient f a l l s below 0.9 the data should be plotted on a semilogarithmic graph and engineering judgement should be used in accepting the results and subsequent evaluation. 256 F.3 FLOWCHART STRUT PRINT BrtXEftOM INFORMATION TEST DATA FOR RERDINB I ECHJPRINT ALL DATA PAIRS UPDATE ALL TEST SUMPTIONS BUJJLATE REGRESSION COEFFICIENTS Tl i AND K PRINT ALL RESULTS 257 F.4 'LIST OF VARIABLES V a r i a b l e Name Function Type A Y i n t e r c e p t i n r e g r e s s i o n r B slope i n re g r e s s i o n r B$(I) v a r i a b l e s used t o co n t a i n p r i n t i n g headers s BDEPTH depth t o bottom of t e s t s e c t i o n r C$ v a r i a b l e used t o c o n t a i n p r i n t i n g headers s DAT$ date s HRAT(I) excess head r a t i o r HREF excess head value at TO r K h y d r a u l i c c o n d u c t i v i t y r L len g t h of t e s t s e c t i o n r LOGRAT(I) n a t u r a l l o g a r i t h m of HRAT(I) r LEVEL(I) depth t o water i n rod at TIME(I) r MEASNUM number of readings r MINTIME(I) time i n minutes . seconds r MIN minutes p o r t i o n of time reading i PIEZO$ piezometer number s RPIPE inner r a d i u s of rods r RHOLE ra d i u s of d r i l l h ole being t e s t e d r RR c o d f f i c i e n t of determination r SEC seconds p o r t i o n of time reading i SIGX summation of TIME(I) r SIGY summation of LOGRAT(I) r SIGXY summation of TIME(I)*LOGRAT(I) r SIGXX summation of TIME(I)~2 r SIGYY summation of L0GRAT(I)'>2 r TDEPTH depth t o top of t e s t s e c t i o n r TIME(I) time i n seconds i TO time f a c t o r r WT depth t o water t a b l e r 258 F.5 PROCEDURE FOR USE Program EQFHEAD i s f u l l y i n t e r a c t i v e , prompting f o r a l l required i n p u t , computing a l l parameters, and p r i n t i n g a l l r e s u l t s . The order of data entry corresponds e x a c t l y t o the order that data i s recorded on the f i e l d data sheet. Procedure: - p r i n t e r on l i n e - run EQFHEAD - enter t e s t i n f o r m a t i o n - enter time-depth data p a i r s i n sequence - output i s p r i n t e d - check c o e f f i c i e n t of determination f o r l i n e a r i t y 259 F.6 PROGRAM CODE 1000 1081 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1813 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1842 1043 1044 1045 1046 1847 1848 1049 1050 1051 1052 =»»***#•*»»»*•»#•»**#**##*#•»•»*#•»**•»***»*•»*#•»• ' PROGRAM EQFHEAD ' *•»#**##»•»»»•»**#*»*»#*#•*#•»»#»**•»*#*»•*•»* 'THIS PROGRAM CALCULATES THE HYDRAULIC CONDUCTIVITY FROM FALLING 'HEAD TEST DATA BASED ON THE HVORSLEV PIEZOMETER TEST METHOD, t 'DECLARE ARRAY SIZES DIM MINTIME (30),TIME(30),HRAT(30),LOGRAT(30),LEVEL(38) » 'DECLARE TEST CONSTANTS (CHANGE IN PROGRAM IF REQUIRED) RPIPE=.00775 RHOLE=.83493 L=307! i CLS 'ENTER TEST SPECIFIIC INFORMATION INPUT"DATE =";DAT* INPUT"PIEZOMETER NUMBER =";PIEZO« INPUT-NUMBER OF RODS ON =";TDEPTH INPUT"WATER TABLE <? (in tn) =":WT INPUT"PACKER PRESSURE ( i n psi) =";PACKP INPUT"NUMBER OF MEASUREMENTS =";MEASNUM TDEPTH=TDEPTH»3. 07+1. 219 BDEPTH=TDEPTH+(L/100) 'ENTER TIME AND LEVEL FOR EACH MEASUREMENT FOR 1=1 TO MEASNUM INPUT"TIME (min) , LEVEL (meters)";MINTIME(I),LEVEL(I) MIN=INT(MINTIME(I)) SEC=(MINTIME(I)-MIN)#100 TIME(I)=MIN*68+SEC ' CALCULATE (HT-HE)/(H0-HE) HRAT(I)=(WT-LEVEL(I))/(WT-LEVEL(1)) LOGRAT(I)=LOG(HRAT(I)) NEXT I HREF=.632»WT 'PRINT ALL INFORMATION LPRINT " LPRINT " B*(l)=" B*(2>=" B*(3)=" B*(7)=" B*(4)=" B*(5)=" B*(6)=" FALLING HEAD TEST CALCULATIONS" TEST DATE PIEZOMETER NUMBER TEST INTERVALS PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS FROM TO \ \ #### V ## (m)" (rn) " ( o s i ) ' (tn) " LPRINT CHR*(10) LPRINT USING B* (1) LPRINT USING B*(2) LPRINT USING B*(3> LPRINT USING B*(7) LPRINT USING B*(4) LPRINT USING B*(5) DAT* PIEZOS TDEPTH BDEPTH PACKP WT 260 1053 LPRINT USING BS(6>;MEASNUM 1054 LPRINT CHR*<27)CHR*<11)CHR*C48)CHR*(53) 1055 LPRINT" TIME LEVEL RATIO LOG-RRTIO" 1056 LPRINT" • " 1057 C*= " ###.## ##.#### ##.#### 1058 FDR 1=1 TO MERSNUM 1059 LPRINT USING C*:MINTIME<I>,LEVEL<I),HRRT(I),LOGRRT(I) 1060 NEXT I 1061 LPRINT 1063 LPRINT USING " REFERENCE DEPTH =###.##";HREF 1063 LPRINT CHR*<27>CHR*<11)CHR»<48)CHR*C53> 106* ' 1065 'SUM UP ALL REQUIRED COEFFICIENTS 1066 SIGX=0 1067 SIGY=0 1068 SIGXX=B 1063 SIGYY=0 1070 SIGXY=0 1071 FOR 1=1 TO MERSNUM 1072 SIGX=SIGX+TIME(I) 1073 SIGY=SIGY+LOGRRT(I) 1074 SIGXX=SIGXX+TIME<I>~£ 1075 SIGYY=SIGYY+L0GRRT(I>~2 1076 SIGXY=SIGXY+TIME <I)*LOGRRT(I) 1077 NEXT I 1078 ' 1079 'CRLCULRTE SLOPE B, Y INTERCEPT R, AND REGRESSION COEFFICIENT RR 1080 B=(MERSNUM*SIGXY-SIGX»SIGY)/<MEASNUM#SIGXX-SIGX~2> 1081 A=(SIGY—B*SIGX)/MEASNUM 1082 RR=<A»SIGY+B*SIGXY-(1/MEASNUM)*<SIGY~2>)/(SIGYY-(1/MERSNUM)*SIGY~£> 1083 ' 1084 'CALCULATE T0 AND HYDRAULIC CONDUCTIVITY K 1085 T0=(-1-A)/B 1086 K=RPIPE~£*LOG(L/RHOLE> / <2»L#T0>*10B 1087 ' 1088 'PRINT ALL CALCULATED VALUES 1083 LPRINT 1090 LPRINT USING" SLOPE B =##. ###'"^";B 1091 LPRINT USING" Y INTERCEPT A =##. ###"--^"-fi 1092 LPRINT USING" RR COEFFICIENT =##.###";RR 1093 LPRINT USING" T0 =##.###"^~-«:T0 1094 LPRINT CHR*(10) 1095 C*=" HYDRAULIC CONDUCTIVITY K =##. #tt#~~~ (crn/s) " 1036 LPRINT USING C*;K 1097 LPRINT CHR*<12) 1098 STOP 1099 END 261 APPENDIX G TESTING EQUIPMENT G . l EQUIPMENT LIST This s e c t i o n serves as a c h e c k l i s t of a l l equipment r e q u i r e d f o r s u c c e s s f u l t e s t i n g w i t h the pneumatic packer apparatus. TRIPOD ASSEMBLY - t r i p o d l e g s , 3 - t r i p o d braces, 3 - nuts and b o l t s f o r b i n d i n g t r i p o d , 7, 3/8" diameter, 4" long - polypropelene rope f o r l a s h i n g t r i p o d braces 3, 2 m. long - polypropelene rope f o r t y i n g of base, 1, 15 m. long PACKER ASSEMBLY - bottom pneumatic packer - top pneumatic packer - brass reducers, 2 - s t e e l pipe reducer, 1 - p e r f o r a t e d rod between packers, 1 - s p a g h e t t i t u b i n g coupler f o r connecting packers, 1, 3.15 m. long NITROGEN SUPPLY - n i t r o g e n (N2) c y l i n d e r - r e g u l a t o r - T coupler and bleeder valve - s p a g h e t t i t u b i n g on spool - a d d i t i o n a l s p a g h e t t i tubing f o r r i s i n g head t e s t s ( o p t i o n a l ) WATER SUPPLY - f o u r t y f i v e g a l l o n b a r r e l s , 2 or 3 - p l a s t i c syphon hose, 2 cm. diameter, 4 m. long - funnel TOOLS - horseshoe p l a t e - s t e e l h o i s t i n g cable w i t h s w i v e l attached, 5 m. - polypropelene h o i s t i n g rope, 10 m. - pipe wrenches, 2, 12" - crescent wrench, 1, 8" - a i r l i n e wrench, 1, 7/16" or 11 mm - hack saw - p u l l y w i t h rope loop attached - come along ( o p t i o n a l t o 100 f t . unless rods stuck) - s h a c k l e s , 3, 3/8" - e l e c t r i c i a n s tape - bucket MONITORING EQUIPMENT - water l e v e l probe - stop watch - data sheet on c l i p board 262 G.2 EQUIPMENT SETUP This section l i s t s the sequential steps for setting up the f a l l i n g head test apparatus. The proper assembly of the various systems is illustrated in Figures G.l to G.3. CONSTRUCTION OF TRIPOD: - place two rusty legs side by side shackles up and bolt together at top. - bolt black cross brace to legs so one side of cross brace projects out. The A frame should be completely bolted, not lashed. - bolt third leg to lower hole in rusty tripod leg so shackle faces inside. Use upper hole on third leg. - loop pulley over tripod. - raise tripod. - bolt one end of each remaining brace to legs. Lash other end. - lash bottom of tripod with rope. CONNECTING NITROGEN SUPPLY: - remove safety cap from cylinder. - clean out threads in bottle by blowing out and wiping any visible d i r t . - screw in regulator. Tighten snuggly. - turn main valve on, listen for leaks. If leaking tighten regulator bolt more snuggly i f possible. - check pressure in bottle. Pressure should be at least 500 p. s . i . WATER SUPPLY: - place one barrel upside down near tripod. - place survey stakes across barrel. - place second barrel on top. - f i l l by syphoning from d r i l l service truck. ASSEMBLY OF PACKERS: - screw brass reducer into bottom packer and tighten. - screw perforated rod into bottom reducer and tighten. - screw brass reducer into top packer and tighten. - attach spaghetti tubing coupler to bottom packer. - tape tubing to perforated rod. - place lower assembly into hole. Hold onto i t carefully. - attach upper packer to assembly. - attach tubing "coupler to upper packer. - lower slightly and attach main a i r l i n e to top of upper packer. - tape a i r l i n e twice to maintain i t in the groove on the upper packer. Make sure that the a i r l i n e can move through the groove as the packer shrinks several centimeters on inflation and would rip the a i r l i n e i f i t were taped firmly. - attach swivel to f i r s t d r i l l rod and raise up tower. - screw the rod into the packer assembly. - tape a i r l i n e to center of rod. - lower packers down the hole, adding additional rods as required. 263 Figure G-l Packer Assembly To r e e l and r e g u l a t o r A i r l i n e t a p e d t o r o d Rod, (3.(37 m long) ( ; » S t e e l P i o e Reducer Upper Pneumatic P a c k e r B r a s s Reducer A i r l i n e , 3.15 m l o n g w i t h f e m a l e c o u p l e r s on ends P e r f o r a t e d Rod, t e s t s e c t i o n i s 3.197 m l o n g B r a s s Reducer Lower Pneumatic P a c k e r 264 Figure G-2 PNEUMATIC PACKER SYSTEM BLEEDER LINE TO PACKERS NITROGEN BOTTLE REGULATOR Figure G-3 TESTING TRIPOD SET-UP WATER BARREL R FOR EXTRA HEAD 265 G.3 TESTING PROCEDURE This s e c t i o n l i s t s the s e q u e n t i a l steps f o r completing a f a l l i n g head t e s t . The steps are as f o l l o w s ; - lower packer assembly t o d e s i r e d t e s t i n t e r v a l , (must be below water t a b l e ) - check e q u i l i b r i u m water l e v e l i n rods and outside c a s i n g . - a t t a c h a i r l i n e t o r e g u l a t o r . - s t a r t i n f l a t i n g packers, f i r s t at 50 p s i , then g r a d u a l l y i n c r e a s i n g pressure t o 175 p s i over 5 t o 10 minutes. - at t h i s p o i n t rods should r i s e up s l i g h t l y so no weight remains on horseshoe. - check that packers are h o l d i n g by l i f t i n g up on horseshoe. - l i s t e n f o r a i r leaks i n h o l e . - check water l e v e l s i n s i d e and o u t s i d e of rod. I f l e v e l s d i f f e r then i t i s l i k e l y t h a t a good s e a l has been e s t a b l i s h e d . - s t a r t f i l l i n g the rod with water. Syphon from the top b a r r e l . - i f l e v e l cannot be brought up t o surface a f t e r 1/3 of a b a r r e l has been poured down the hole i t i s l i k e l y t h a t the rock i s s u f f i c i e n t l y permeable t o a l l o w water t o d r a i n as f a s t as i t i s added. In that case the t e s t can be s t a r t e d at the maximum l e v e l t hat can be obtained a f t e r pouring another 1/4 b a r r e l down the hole. - measure water l e v e l and record time. - repeat measurements approximately every 50 cm. of drop i n water l e v e l . - continue monitoring u n t i l excess head has droped t o 1/3 of i n i t i a l v a lue. - upon completion of t e s t t u r n n i t r o g e n supply o f f , bleed pressure, and d i s c o n e c t a i r l i n e from r e g u l a t o r so spool can t u r n f r e e l y . 266 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-5 10.43 13.50 8.42 150 GABBRO D2 (m) (m) (m) ( p s i ) DATE: 84/08/04 TECHNICIAN: TS /EC READING # 1 2 3 4 5 6 7 8 9 TEST RECORD TIME 0.00 1.05 1.13 1.18 1.27 1.40 1.51 2.31 2.40 WATER LEVEL 0.55 0.78 0.98 1.25 1.77 2.01 2.63 6.38 6.93 267 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-5 16.57 (m) 19.64 (m) 175 8.55 (m) (psi) GABBRO D2 DATE: 84/08/04 TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 0.00 10.00 20.00 30.00 40.00 0.00 0.16 0.29 0.42 0.55 268 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-5 19.64 22.71 8.55 175 GABBRO D2 (m) (m) (m) (psi) DATE: 84/08/04 TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 0.00 0.37 0.66 0.91 1.10 1.30 1.46 1.60 269 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-6 16.57 19.64 10.46 175 LAPILLI D2 (m) (m) (m) (psi) DATE: 84/08/14 TECHNICIAN: TS /EC READING f TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 11 0.42 1.08 1.26 1.42 2.05 2.39 3.00 3.37 4.04 4.56 6.00 9.55 10.13 10.26 10.31 10.35 10.39 10.40 10.42 10.42 10.43 10.46 270 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-6 19.64 22.71 10.46 175 D2 DATE: 84/08/14 LAPILLI (m) (m) (m) (psi) TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0.00 0.14 0.26 0.38 0.54 1.11 1.29 1.54 2.27 2.53 3.30 4.25 5.30 6.45 8.34 8.00 8.13 8.58 8.74 8.91 9.04 9.20 9. 9. 9. 9. 38 53 63 86 10.02 10.15 10.24 10.34 271 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-6 22.71 25.78 10.49 175 LAPILLI D2 (m) (m) (m) (psi) DATE: 84/08/14 TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 11 0.45 1.06 1.27 1.55 2.15 2.45 3.07 3.35 5.00 5.31 7.02 6.38 7.73 8.52 9.27 9.61 9.93 10.09 10.21 10.43 10.48 10.47 272 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-7 16.57 19.64 15.42 150 D2 DATE: 84/08/15 LAPILLI (m) (m) (m) ( p s i ) TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 11 12 0.29 1.05 2.03 3.15 6.36 9.07 10.36 15.40 20.30 28.04 37.05 39.47 0.42 0.74 1.10 1.64 2.97 3.84 4.28 5.68 6.85 8.31 9.68 9.99 273 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-7 16.57 19.64 14.62 150 GABBRO D2 DATE: 84/08/15 (m) (m) (m) (psi) TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 0.04 0.15 0.23 0.35 0.47 1.09 1.33 1.45 1.55 2.38 3.02 3.23 3.36 4.03 4.26 4.55 5.27 6.42 7.52 9.06 9.59 12.12 5.20 7.18 8.39 9.43 10.17 11.90 12.48 12.79 13.01 13.29 13.39 13.67 13.73 13.84 13.92 13.99 14.06 14.20 14.29 14.34 14.37 14.46 274 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-8 19.64 22.71 17.14 175 GABBRO D2 (m) (m) (m) (psi) DATE: 84/08/17 TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 0.00 2.53 5.08 10.32 16.12 23.25 29.35 49.02 0.00 0.23 0.38 0.77 1.09 1.51 1.88 3.09 275 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: P-8 22.71 25.78 16.42 175 GABBRO D2 DATE: 84/08/20 (m) (m) (m) ( p s i ) TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 11 12 13 0.33 1.05 1.27 1.57 2.39 3.03 4.38 6.45 9.27 13.22 23.09 28.00 34.21 0.44 0.70 0.87 1.13 1. 1. 2. 3. 4. 6. 44 63 32 13 29 30 8.23 9.46 10.91 276 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE:. STRUCTURAL DOMAIN: K-1 7.36 (m) 10.43 (m) 100 1.20 (m) ___ (psi) LAPILLI D2 DATE: 84/08/01 TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 0.00 1.16 0.00 1.19 277 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: K-2 22.71 25.78 17.80 100 D2 DATE: 84/08/30 LAPILLI (m) (m) (m) (psi) TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.16 0.27 0.43 1.02 1.31 1.51 2.20 2.40 3.23 4.26 6.35 8.54 12.06 16.20 1.50 2.15 3.20 4.25 5.80 6.30 7.20 8.00 9.00 10.10 12.00 13.65 15.20 16.60 278 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: K-2 25.78 28.85 18.10 125 LAPILLI D2 (m) (m) (m) (psi) DATE: 84/09/03 TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 11 0.00 0.29 0.52 1.23 2.00 2.54 4.35 7.25 10.56 12.28 13.32 0.00 2.45 3.30 4.20 5.10 6.30 8.00 10.20 12.30 13.05 13.45 279 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: K-2 31.92 34.99 10 18.10 125 LAPILLI D2 (m) (m) (m) (psi) DATE: 84/09/03 TECHNICIAN: TS /EC READING # TEST RECORD TIME WATER LEVEL 1 2 3 4 5 6 7 8 9 10 0.00 0.44 1.24 2.45 5.30 7.32 8.24 12.20 15.43 17.30 0.00 0.60 1.00 1.90 3.35 4.30 5.00 6.48 7.70 8.15 280 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER. TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/08/04 = P5 FROM 16.57 (rn) TO 19.64 (rn) = 175.00 <Dsi) = 8. 42 (rn) 5 TIME LEVEL RATIO LOG-RATIO 0.00 0.00 1.0000 0.0000 10.00 0. 16 0.9810 -0.21192 20.00 0.29 0.9656 -0.0350 30.00 0.42 0.9501 -0.0512 40.00 0.55 0.9347 -0.0676 REFERENCE DEPTH = 5.32 SLOPE B =-2.785E-05 Y INTERCEPT A =-1.174E-03 RR COEFFICIENT = 0.999 T0 = 3.587E+04 HYDRAULIC CONDUCTIVITY K = 1.221E-07 (cm/s) 281 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/08/04 = P5 FROM 19.64 <m> TO £2.71 <m) = 175.00 (psi) 8. 55 <m) 8 TIME LEVEL RATIO LOG-RATIO 0. 00 0. 00 1.0000 0.0000 10. 00 0. 37 0.9567 -0.0442 £0. 00 0. 66 0.9228 -0.0803 30. 00 0. 91 0.8936 -0.1125 40. 00 1. 10 0.8713 -0.1377 50. 00 1. 30 0.8480 -0.1649 £0. 00 1. 45 0.8292 -0.1872 70. 00 1. 50 0.8129 -0.2072 REFERENCE DEPTH = 5.40 SLOPE B =-4.850E-05 Y INTERCEPT A . =-1.493E-02 RR COEFFICIENT = 0.984 T0 = £.031E+04 HYDRAULIC CONDUCTIVITY K = 2.156E-07 (cm/s) 282 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/08/14 = P6 FROM 16.57 (m) TO 19.64 (m> = 175.00 (psi) 10.46 (m) • = 11 TIME LEVEL RATIO LOG-RATIO 0.42 9.55 1.0000 0.0000 1.08 10. 13 0.3626 -1.0144 1.26 10.26 0.2198 -1.5151 1.42 10.31 0.1648 -1.8026* 2.05 10.35 0. 1209 -2.1130 2.39 10.39 0.0769 -2.5650 3.00 .10.40 0.0659 -2.7191 3.37 10.42 0.0495 -3.0068 4.04 10.42 0.0440 -3. 1246 4.56 10.43 0.0330 -3.4123 6.00 10.46 0.0055 -5.2040 REFERENCE DEPTH = 6.61 SLOPE B =-1.315E-02 Y INTERCEPT A =-1.602E-01 RR COEFFICIENT = 0.923 T0 = 6.385E+01 HYDRAULIC CONDUCTIVITY K = 6.858E-05 (cm/a) 283 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS » 84/08/14 = PS FROM 13.64 (rn) TO £2.71 (ra) = 175.00 (psi) 10.46 (rn). 15 I ME LEVEL RATIO LOG-RATIO 0. 00 8. 00 1 . 0000 0.0000 0. 14 8. 13 0.9472 -0.0543 0.26 8. 58 0.7642 -0.2689 0. 28 8. 74 0.6392 -0.357B 0. 54 8.91 0.6301 -0.4619 1. 11 9.04 0.5772 -0.5435 1.29 9. 20 0.5122 -0.6690 1. 54 9.38 0.4390 -0.8232 2.27 9. 53 0.3780 -0.9727 2.53 9. 63 0.3374 -1.0865 3.30 9. 86 0.2439 -1.4110 4. 25 10. 02 0.1789 -1.7211 5. 30 10. 15 0.1260 -2.0713 6. 45 10. 24 0.0894 -2.4143 8. 34 10. 34 0.0488 -3.0204 REFERENCE DEPTH « 6.61 SLOPE B =-5.814E-03 Y INTERCEPT A =-1.092E-«l RR COEFFICIENT = 0.995 T0 = 1.532E+02 HYDRAULIC CONDUCTIVITY K = 2.858E-05 (cm/s) 284 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/08/14 = P6 FROM 22.71 (rn) TO 25.78 (rn) » 175.00 (psi) 10.49 (rn) = 11 TIME LEVEL RATIO 0. 45 6. 38 1.0000 1. 06 7. 73 0.6715 1.27 8. 52 0.4793 1. 55 9. £7 0.£968 2. 15 9. 61 0.2141 £.45 9. 93 0.1363 3. 07 10. 09 0.0973 3 • *i5 10. £1 0.0681 5. 00 10. 43 0.0146 5. 31 10. 48 0.0024 7.02 10. 47 0.0049 LOG-RATIO 0.0000 -0.3982 -0.7354 -1.2146 -1.5413 -1.9932 -2.3297 -2.6864 -4.2268 -6.0186 -5.3255 REFERENCE DEPTH = 6.63 SLOPE B =-1.620E-02 Y INTERCEPT A =» 6. 392E-01 RR COEFFICIENT = 0.938 T0 = l.01£E+0£ HYDRAULIC CONDUCTIVITY K - 4.327E-05 (cm/s) £85 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/08/15 = P7 FROM 16.57 (m) TO 19.64 (m) = 150.00 ( p s i ) 15.42 (rn) 12 TIME LEVEL RATIO LOG-RATIO 0. 29 1. 05 2. 03 3. 15 6. 36 9. 07 10. 36 15. 40 20. 30 28. 04 37. 05 39. 47 0. 42 0. 74 1. 10 1. 64 2. 97 3. 84 4. 28 5. 68 1. 85 8. 31 9. 68 9.99 1.0000 0.9787 0.9547 0. 9187 0.8300 0.7720 0.7427 0.6493 0.9047 0.4740 0.3827 0.3620 0.0000 -0.0216 -0.0464 -0.0848 -0.1863 -0.2588 -0.2975 -0.4318 -0.1002 -0.7465 -0.9606 -1.0161 REFERENCE DEPTH = 9.75 SLOPE B Y INTERCEPT A RR COEFFICIENT T0 =-4.111E-04 = 1.237E-0S -= 0.882 = 2.462E+03 HYDRAULIC CONDUCTIVITY K = 1.778E-06 (cm/s) 286 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/88/17 = P7 FROM £2.71 (rn) TO £5.78 (r.i) = 150.00 (psi) 14.62 (rn) 22 I ME LEVEL RATIO LOG-RAT 0. 04 5. 20 1.0000 0.0000 0. 15 7. 18 0.7898 -0.2360 0. 23 8. 39 0.6614 -0.4135 0. 35 9. 43 0.5510 -0.5961 0. 47 10. 17 0.47£4 -0.7499 1. 09 11. 90 0.£887 -1.2422 1. 33 1£. 48 0.2272 -1.4820 1. 45 1£. 79 0.1943 -1.6385 1.55 13. 01 0.1709 -1.7666 2. 38 13. £9 0.1412 -1.9577 3. 02 13. 33 0.1306 -2.0358 3. £3 13. 67 0.1008 -£.£941 3. 36 13. 73 0.0945 -2.3594 4. 03 13. 84 0.0828 -2.4913 4. £6 13. 92 0.0743 -2.5995 4. 55 13. 99 0.0669 -2.7049 5. £7 14. 06 0.0594 -£.8227 6. 4£ 14. £0 0.0446 -3.1103 7. 5£ 14. £9 0.0350 -3.3515 3. 06 14.34 0.0297 -3.5158 9.59 14. 37 0.0265 -3.6291 1£. 12 14. 46 0.0170 -4.0754 REFERENCE DEPTH » 9.24 SLOPE B =-5.319E-03 Y INTERCEPT A =-8.043E-01 RR COEFFICIENT = 0.880 T0 = 3.679E+01 HYDRAULIC CONDUCTIVITY K = 1.190E-04 ( c m / s ) 287 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/08/17 = PB FROM 19.64 (ni) TO £2.71 (rn) = 150.00 (psi) 17. 14 (rn) 8 TIME LEVEL RATIO 0. 00 0. 00 1.0000 £. 53 0. 23 0.9866 5. 08 0.38 0.9778 10. 3£ 0.77 0.9551 16. 12 1. 09 0.9364 £3. 25 1. 51 0.9119 29. 35 1. 88 0.8903 49.02 3.09 0.8197 LOG-RATIO 0.0000 -0.0135 -0.0224 -0.0460 -0.0657 -0.0922 -0.1162 -0.1988 REFERENCE DEPTH 10. 83 SLOPE B Y INTERCEPT A RR COEFFICIENT T0 -6.642E-05 -1.208E-03 0.999 1.504E+04 HYDRAULIC CONDUCTIVITY K = 2.91£E-07 (cm/s) £88 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/08/213 = PB FROM 22.71 (rn) TO £5.78 (rn) = 175.00 (psi) 16.42 (rn) 13 TIME LEVEL RATIO LOG-RATIO 0. 33 1. 05 1.27 1.57 2.39 3. 03 4. 38 6. 45 9. 57 13. ££ 23. 03 £8. 00 34. 21 0. 44 0. 70 0. 87 1. 13 1. 44 1. 63 2.32 3. 13 4. 29 6. 30 8. 23 9. 46 10. 91 1.0000 0.9837 0.9731 0.9568 0.9374 0.9255 0.8824 0.8317 0.7591 0.6333 0.5125 0. 4355 0.3448 0.0000 -0.0164 -0.0273 -0.0441 -0.0646 -0.0774 -0.1252 -0.1843 -0.2757 -0.4568 -0.66B4 -0.8312 -1.0648 REFERENCE DEPTH = 10.38 SLOPE B Y INTERCEPT A RR COEFFICIENT T0 -5.153E-04 1.631E-02 0. 996 1.97£E+03 HYDRAULIC CONDUCTIVITY K = 2.220E-06 (cm/s) 289 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS FROM TO 84/08/81 K l 7. 36 10. 43 100.00 1. 20 2 (m) (m> (psi) (ni) TIME LEVEL RATIO LOG-RATIO 0. 00 0. 16 0. 00 1. 19 1.0000 0.0083 0.0000 -4.7875 REFERENCE DEPTH = 0. 76 SLOPE B Y INTERCEPT A RR COEFFICIENT T0 -2.992E-01 0. 000E+00 1. 000 3.342E+00 HYDRAULIC CONDUCTIVITY K 1.310E-03 (cm/s) 290 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 34/138/30 = K2 FROM 22.71 (m) TO 25.78 (m) = 100.00 <psi) 17.80 (r.i) 14 IME LEVEL RATIO LOG-RATIO 0. 16 1. 50 1.0000 0.0000 0.27 2. 15 0.9601 -0.0407 0. 43 3. 20 0.8957 -0.1101 1. 02 4. 25 0.8313 -0.1848 1. 31 5. 80 0.7362 -0.3063 1. 51 6. 30 0.7055 -0.3488 2.20 7. £0 0.6503 -0.4303 2. 40 8. 00 0.6012 -0.5088 3. 23 9. 00 0.5399 -0. 6164 4. £6 10. 10 0.4724 -0.7499 6.35 12. 00 0.3558 -1.0333 8. 54 13. 65 0.2546 -1.3681 12. 06 15. £0 0.1595 -1. 8357 16. 20 16. 60 0.0736 -2.6088 REFERENCE DEPTH = 11.25 SLOPE B =-2.584E-03 Y INTERCEPT A =»-3. 167E-02 RR COEFFICIENT = 0.996 T0 - 3.748E+02 HYDRAULIC CONDUCTIVITY K = 1.168E-05 (cm/s) 291 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/09/03 =» K2 FROM £5.78 (m) TO £8.85 (rfl) = 125.00 (psi) = 18.10 (ni) 11 TIME LEVEL RATIO LOG-RATIO 0. 00 0.29 0. 5£ 1. £3 2.00 £. 54 4.35 7. £5 10. 56 12. £8 13. 32 0. 00 2. 45 3. 30 4. 20 5. 10 6. 30 8. 00 10.20 12. 30 13. 05 13. 45 1.0000 0.8646 0.8177 0.7680 0.7182 0.6519 0.5580 0. 4365 0.3204 0.2790 0.2569 0.0000 -0.1454 -0.2013 -0.2640 -0.3310 -0.4278 -0.5834 -0.8230 -1.1381 -1.2765 -1.3590 REFERENCE DEPTH = 11.44 SLOPE B Y INTERCEPT A RR COEFFICIENT T0 -1.571E-03 -1.112E-01 0.992 5.657E+02 HYDRAULIC CONDUCTIVITY K 7.740E-06 (cm/s) 292 FALLING HEAD TEST CALCULATIONS TEST DATE PIEZOMETER NUMBER TEST INTERVAL: PACKER PRESSURE WATER TABLE NO. OF MEASUREMENTS = 84/09/03 = K2 FROM 31.92 (ni) TO 34.99 (rn) = 125.00 (psi) 18. 10 (ni) 10 TIME LEVEL RATID LOG-RATIO 0.00 0.00 1.0000 0.0000 0.44 0.60 0.9669 -0.0337 1.24 1.00 0.9448 -0.0568 2.45 1.90 0.8950 -0.1109 5.30 3.35 0.8149 -0.2047 7.32 4.30 0.7624 -0.2712 8.24 5.00 0.7238 -0.3233 12.20 6.48 0.6420 -0.4432 15. 43 7.70 0.5746 -0.5541 17.30 8. 15 0.5497 -0.5983 REFERENCE DEPTH « 11.44 SLOPE B =-5.741E-04 Y INTERCEPT A =-1.207E-02 RR COEFFICIENT = 0.998 T0 = 1.721E+03 HYDRAULIC CONDUCTIVITY K = 2.545E-06 (cm/s) 293 H.3 SUMMARY OF PREVIOUS PERMEABILITY TESTING A. TESTING BY GOLDER ASSOCIATES, 1982 PIEZOMETER NUMBER TYPE OF TEST BASIC TIME LAG (sec) LENGTH OF GRAVEL PACK (m) DIAMETER OF GRAVEL PACK (m) HYDRAULIC CONDUCTIVITY (rn/sec) LITHOLOGY AND FORMATION RH-82-01-2 RUT 16 1.4 0.152 8.1x10'* Andesite (Goosly Lake/Buck Creek) -3 RHT 570 2.7 0.152 1.0x10 Andesite (Goosly Lake7Buck cre°k) RH-82-02-2 RHT 351,000 2.7 0.152 2.2x10"'° T i l l RH-82-03-02 RHT 580 2.4 0.152 l.Oxlo" 7 S i l t y Gravel RH-82-05-01 FHT 72,000 3.4 0.152 -to 9.2x10 Undifferentiated Volcanics RH-82-06-01 RHT 77 6.8 0.152 5.0X10"1 Andesite (Goosly Lake/Buck creek) RH-82-08-01 RHT 1,440 16.0 0.152 1.3xl0"f D i o r i t e (?) -02 FHT 830 8.8 0.152 3.7x10'' Ash Tuff B. TESTING BY EQUITY SILVER MINES (Southern T a i l P i t ) HOLE TEST BASIC LENGTH OF HOLE HYDRAULIC NUMBER NUMBER TIME LAG OPEN HOLE DIAMETER CONDUCTIVITY (sec) (m) im) im/s) IB 1 94 3.05 0.07 7.0x10° IB 2 1,040 1.52 0.07 1.0x10, 2A 1 158 3.20 0.07 4.0x10 2A 2 630 6.10 0.07 5.5x10"* 2B 2 800 1.20 0.07 2.0x10 " 7 3A 1 635 3.05 0.07 9.8x10"' 3B 1 112 2.13 0.07 8.0x10 , 43 1 395 1.98 0.07 2.0x10" 5B 1 92 1.31 0.07 1.3x10"' 6B 1 68 1.82 0.07 1.4x10"' 294 EQUITY SILVER MINES LTD. FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: - TO: NUMBER OF RODS ON: WATER TABLE @: PACKER PRESSURE: ROCK TYPE: STRUCTURAL DOMAIN: 2-A SOUTHERN TAIL 7.36 (m) DATE: 81/03/19 10.43 2.41 150 TECHNICIAN: PB (m) (m) (psi) READING #• TEST RECORD TIME WATER LEVEL 1 0.30 0.46 2 1.00 0.75 3 1.32 1.03 4 2.08 1.28 5 2.36 1.46 6 3.01 1.61 7 3.25 1.73 8 4.00 1.85 9 4.28 1.94 10 5.00 2.01 11 6.15 2.13 12 6.56 2.20 13 7.44 2.24 14 8.21 2.26 15 9.35 2.27 16 10.05 2.30 17 11.06 2.32 18 12.28 2.33 19 16.15 2.31 20 20.30 2.33 21 26.00 2.31 22 41.45 2.35 23 52.40 2.39 24 57.50 2.39 25 62.00 2.40 295 FALLING HEAD TEST CALCULATIONS TEST DATE = 81/03/13 PIEZOMETER NUMBER = £A S. T. TEST INTERVAL: FROM 7.36 (m) TO 10.43 (ra) PACKER PRESSURE = 150.00 (psi) WATER TABLE = 2.41 (rn) NO. OF MEASUREMENTS = 25 TME LEVEL RATIO LOG-RAT; 0. 30 0. 46 1.0000 0.0000 1. 00 0. 75 0.8513 -0.1610 1.32 1. 03 0.7077 -0.3457 2. 08 1. 28 0.5795 -0.5456 2.36 1. 46 0.4872 -0.7191 3.01 1. 61 0.4103 -0.8910 3.25 1. 73 0.3487 -1.0535 4.00 1.85 0.2872 -1.2476 4. 28 1. 34 0.2410 -1.4229 5.00 2. 01 0.2051 -1.5841 6. 15 2. 13 0. 1436 -1.9408 6. 56 2.20 0.1077 -2.2285 7. 44 2. 24 0.0872 -2.4398 8.21 2. 26 0.0769 -2.5649 3. 35 2. 27 0.0718 -2.6339 10. 05 2. 30 0.0564 -2.8751 11. 06 2. 30 0.0564 -2.8751 12.28 2. 30 0.0564 -2.B751 16. 15 2. 32 0.0462 -3.0758 20. 30 2. 33 0.0410 -3.1936 26. 00 2. 31 0.0513 -2. 9704 41. 45 2.35 0.0308 -3.4812 52. 40 2. 39 0.0103 -4.5799 57.50 2. 39 , 0. 0103 -4.5739 62. 00 2. 40 0.0051 -5.2730 REFERENCE DEPTH = 1.52 SLOPE B =-1.127E-03 Y INTERCEPT A =-1.202E+0® RR COEFFICIENT = 0.764 T0 =-l.791E+0£ HYDRAULIC CONDUCTIVITY K =-2.445E-05 (cm/s) 296 E Q U I T Y S I L V E R M I N E S L T D . FALLING HEAD PERMEABILITY TEST DATA SHEET DRILL HOLE NUMBER: TEST INTERVAL - FROM: (m) - TO: (m) NUMBER OF RODS ONi WATER TABLE <?: (m) PACKER PRESSURE: (psi) ROCK TYPE: STRUCTURAL DOMAIN: TEST RECORD READING # TIME WATER LEVEL 1 2 3 4 5 6 7 a 9 10 11 12 13 14 15 16 17 18 19 20 DATE: TECHNICIAN: 297 APPENDIX I . PROGRAM BQDRAWDOWN 1.1 OBJECTIVE Program EQDRAWDN was developed t o model the response of the Main Zone water t a b l e t o w e l l p o i n t dewatering. The program uses the Theis s o l u t i o n t o the boundary value problem of a s i n g l e w e l l dewatering an unconfined h o r i z o n t a l a q u i f e r of constant t h i c k n e s s and homogeneous and i s o t r o p i c h y d r a u l i c parameters. The program can model the t r a n s i e n t response of the water t a b l e at any p o s i t i o n and time. The purpose of the numerical modelling i s t o determine whether: 1. a s u f f i c i e n t l y l a r g e drawdown cone w i l l be developed around each pumping w e l l , 2. the r a t e of water t a b l e drawdown w i l l be f a s t enough t o dewater i n advance of mining a c t i v i t y , 3. t o study the s e n s i t i v i t y of the system t o changes i n a q u i f e r p r o p e r t i e s and pumping r a t e s , and 4. t o a s s i s t i n the design of the dewatering system a f t e r a l l important h y d r a u l i c parameters (as i d e n t i f i e d from s e n s i t i v i t y study i n step 3.) have been adequately e s t a b l i s h e d from i n - s i t u t e s t s . 298 1-2 T H E D R Y O F S I M U L A T I N G P U M P I N G W E L L DFAWDOWN The boundary value problem of a s i n g l e w e l l dewatering an unconfined a q u i f e r i s i l l u s t r a t e d below: Q homogeneous i s o t r o p i c \ \ ~ W 777 « / W 777 S\ fi — H(oo ,t) = H, X - H ( r , t l H(r,0) = H e "SK fir VV 7fi 7T7- W W> 7" *V The governing d i f f e r e n t i a l equation f o r t h i s boundary value probem i s the flow equation: d l h + d^h = S_.dh 1. dx 1 d y 1 T ' dt where: h = t o t a l head S = s p e c i f i c y i e l d - The volume of water t h a t an unconfined a q u i f e r r e l e a s e s from storage per u n i t surface area of a q u i f e r per u n i t d e c l i n e i n water t a b l e . T = t r a n s m i s s i v i t y - Product of h y d r a u l i c c o n d u c t i v i t y and sa t u r a t e d t h i c k n e s s of the a q u i f e r . Equation 1 can be s i m p l i f i e d by transforming t o r a d i a l c oordinates: § \ + _1_. dh = S, . dh dr T dr T dt The i n i t i a l c o n d i t i o n t o t h i s B.V.P. i s : h(r,0) = h 0 i n i t i a l water t a b l e at h . The boundary c o n d i t i o n s are: h(°°,t) = h„ water t a b l e u n a f f e c t e d by pumping at l a r g e d i s t a n c e s . l i m r dh = Q constant pumping rat e at the w e l l r—>0 dr 2-TT-T p o i n t , (from Darcy's law) 299 The s o l u t i o n t o t h i s B.V.P. was f i r s t worked through by Theis (1935). h ( r , t ) = Q where: 4-T-t dU 4-ff-T J z U = r • S The i n t e g r a l p o r t i o n of t h i s f u n c t i o n i s o f t e n c a l l e d the w e l l f u n c t i o n i n hydrology. An a n a l y t i c a l s o l u t i o n does not e x i s t t o t h i s i n t e g r a l , but an i n f i n i t e s e r i e s s o l u t i o n i s a v a i l a b l e and converges r a p i d l y . E v a l u a t i o n of W e l l Function: The w e l l f u n c t i o n can be evaluated at a p o i n t x by the s e r i e s : e dx = l n ( x ) + a x + a • x + a • x + a 1 x  J x 1! 2-2! 3-3! 4-4! (from CRC Handbook, A-83) The Theis s o l u t i o n r e q u i r e s the d e f i n i t e i n t e g r a l from U t o . This can be c a l c u l a t e d by e v a l u a t i n g the i n t e r g r a l between U and an intermediate p o i n t P and adding t h i s value t o the i n t e g r a l between p and . The l a t t e r value can be obtained from w e l l f u n c t i o n t a b l e s (Freeze, 1981). 300 _ z n n ^ r> n /-00 -< W(U) = ln(p) + I ( - l ) . p - ln(U) - ! ( - ! ) • (U) | e • dx n=l n n! n=l n n i J p x The above expression i s used t o evaluate the w e l l f u n c t i o n i n program eqdrawdn, presented i n appendix H. When U becomes greater than 0.5 the s e r i e s f a i l s t o converge r a p i d l y . When U exceeds 1.0 the s e r i e s becomes divergent and the s e r i e s s o l u t i o n cannot be used. For values of U greater than 0.5 the w e l l f u n c t i o n can be c a l c u l a t e d by e v a l u a t i n g the i n t e g r a l by Simpson's r u l e . This approach i s computationally l e s s e f f i c i e n t so the s e r i e s approach i s used whenever p o s s i b l e . = V3-{ends + 4 odds + 2 evens} Therefore: by Simpson's From Tables Rule r 301 1-3 EQDRAWDN FLOWCHART INPUT 1 INPUT (w\<MrMl INPUT MKT ROLLING PARAMETERS. INPUT ALL TESTING TINES. INPUT ALL TESTING RADII. CALCULATE U PRINT U AND U(U) DN SCREEN. PRINT PARAMETERS TABLE. PRINT HEADER LINES. PRINT DRAUDOUNS AT ALL R FOR CURRENT TINE T( I ) REFORMAT PRINTER SUBROUTIK USERIES iNPun GO SUB 2 W 8 ) — NO CALCULATE CflLXALflTE RECEIVE INPUT FROM CALLING PROGRAM REFRESH SUWTION VARIABLES. CALCULATE SERIES TERN FOR CURRENT L CALCULATE U(U) SUBROUTINE FACTORIAL RECEIVE INPUT FROM CALLING SUBROUTINE. MULTIPLY PRODUCT BY CURRENT II SUBROUTINE FUNCTION INPUT CflLGJLATE RECEIVE INPUT FROM CALLING SUBROUTINE EVALUATE FIX) FOR CURRENT X 303 SUBROUTINE WSIHPSON ASSIGN W(U) FOR 0^ .8 ZERO ALL SUMMATION TERN CALCULATE INCREMENT EVALUATE Fd) INCREMENT X INCREMENT X EVALUATE FU) INCREMENT X EVALUATE FIX) UPDATE SUMMATIONS 304 1.4 LIST OF VARIABLES V a r i a b l e Name Function Type A$ used as p r i n t e r header s B$ used as p r i n t e r header s BLANK used t o i n s e r t blanks f o r l e f t j u s t i f i c a t i o n i of numbers. C$ used as p r i n t e r header s DELH drop i n water l e v e l from i n i t i a l c o n d i t i o n r F$ s t r i n g v a r i a b l e a c t s as l i n e b u f f e r f o r p r i n t i n g s FACT f a c t o r i a l of X i G$ holds decimal character s H(I.J) water l e v e l at T ( i ) , R ( j ) r HO i n i t i a l e l e v a t i o n of water l e v e l r I counter i I I counter i J counter i K h y d r a u l i c c o n d u c t i v i t y r L counter i LENGTH length of b u f f e r , used f o r i n s e r t i n g blanks i LIN$ l i n e b u f f e r v a r i a b l e s LMAX number of increments i n s e r i e s i NUM$ s t r i n g v a r i a b l e used i n time conversion s PI constant r POSI counter used t o i n s e r t blanks i n l i n e b u f f e r i PLOW low bound f o r numerical i n t e g r a t i o n r PHIGH upper bound f o r numerical i n t e g r a t i o n r PINF value of i n t e g r a l between phigh and i n f i n i t y r Q pumping r a t e r R(J) d i s t a n c e from w e l l r RMAX number o f p o s i t i o n s R ( j ) t o be evaluated i SY s p e c i f i c y i e l d r SUM# sum of s e r i e s i n numerical i n t e g r a t i o n d T(I) time r TMAX number of times at which drawdowns are c a l c u l a t e d i THICK t h i c k n e s s of unconfined a q u i f e r r TIMES$ used t o p r i n t time v a r i a b l e s TERM# one term of s e r i e s d U input value f o r w e l l f u n c t i o n r UU# double p r e c i s i o n value of U d W W(U) r X argument f o r f a c t o r i a l subroutine i 305 1.5 P R O C E D U R E F O R U S E Program EQFHEAD was developed t o study the s e n s i t i v i t y of the a q u i f e r system t o changes i n h y d r a u l i c parameters and pumping r a t e s ; t h e r e f o r e , a l l parameters are entered i n t o the program at the beginning of the f i r s t run. Then, i n subsequent runs the user i s asked t o i d e n t i f y which parameters he wishes t o change. A l l others remain as i n the previous run. The program i s f u l l y i n t e r a c t i v e , and r e s u l t s are r e l e a s e d d i r e c t l y t o the l i n e p r i n t e r . Procedure: - P r i n t e r on l i n e . - Load EQDRAWDN - Input appropriate i n i t i a l values f o r the f o l l o w i n g parameters i n the data l i n e s of the program. L i n e 1120: TMAX,RMAX,K(cm/s),THICK(m),SY,Q(1/min),H0 Lin e 1130: T(I) (days) 1=1 t o TMAX Li n e 1140: R(J) (m) J = l t o RMAX - Run - I n d i c a t e which parameters t o be changed when prompted, code 0 on f i r s t run. Note t h a t more than one parameter can be changed during a run. 0 = no changes 1 = change K 2 = change a q u i f e r t h i c k n e s s 3 = change s p e c i f i c head 4 = change pumping r a t e 5 = change times of s i m u l a t i o n 6 = change r a d i i where drawdown computed - Input d e s i r e d parameter as prompted - R e s u l t s p r i n t e d on l i n e p r i n t e r 306 1.6 BQDRAWDN PROGRAM CODE 1000 1 I I I I I I I I H I i m i H W H W W H W t 1005 ' PROGROM EQDRflWDN 1010 • H I H I i m H t H t l l H I I I I H H I I H H I I H I I I I I I I U H H H W H U W H m H H H 1015 'THIS PROGRAM CALCULATES THE DRAWDOWN IN A HORIZONTAL ISOTROPIC AQUIFER 1028 'ACCORDING TO THE THEIS SOLUTION. DRAWDOWN IS CALCULATED AS A FUNCTION 1025 'OF RADIAL POSITION R AND TIME T. 1050 ' 1855 'DIMENSION ALL ARRAYS AND ASSIGN ALL CONSTANTS 1060 DIM H(20,10),R(18),T(28) 1065 PI=3.141532 1080 1 1081 'DATA DECK 1082 DATA 8,6, 1E-97,180,8.05,10,108 1083 DATA 1,5,18,50,100,200,509,1098 1084 DATA 5,18,28,58,100,200 1085 'INPUT CONTROLLING PARAMETERS 1098 READ TMAX,RMAX,K,THICK,SY,9,K8 1895 K=K/108 1096 0=0/60/1000 1108 FOR 1=1 TO TMAX 1185 READ T(I) 1106 T(I)=TU)*24*60*68 1118 NEXT I 1115 FOR J=l TO RMAX 1128 READ R(J) 1125 NEXT J 1138 ' 1135 'CALCULATE DRAWDOWNS AT ALL POSITIONS R FOR A GIVEN TIME T 1148 FOR 1=1 TO TMAX 1145 FOR J=l TO RMAX 1158 U=R(J)A2«SY/(4*K*THICK*T(D) 1151 IF U (.5 THEN GOSUB 1994 ELSE GOSUB 3831 1152 PRINT USING "IMi.tf^ «(U)=##t.itM";U,U 1198 DEU*=Q/(4«PI*K*THICK)*W 1195 HU,J)=H8-DELH 1288 NEXT J 1218 NEXT I 1215 ' 1228 'PRINT OUTPUT ON LINE PRINTER 1225 LPRINT" PUMPING WELL DRAWDOWN SIMULATION' 1238 LPRINT 1235 LPRINT" PARAMETERS" 1248 LPRINT" " 1245 LPRINT 1258 A$=" K tt.tr*"* cs/s" 1255 B*=" THICK = ###.tf o" 1268 C*=" SY = t.lt#" 1265 D$=" Q Ht.lt 1/iin" 1266 0=0*60*1008 1267 K=K*108 1278 LPRINT USING A*;K 1275 LPRINT USING Bt;THICK 1280 LPRINT USING C$;SY 1285 LPRINT USING Dl;Q 1298 LPRINT CHR*(18)* DRAWDOWN RESULTS" 1295 LPRINT " " 1308 LPRINT CHR$(29) 1381 ' 1392 'PRINT OUT HEADER FOR TABLE 1393 LPRINT " TIME RADIAL POSITION (•)" 1395 LINt=" (days)" 1396 FOR 1=1 TO RMAX 1397 NUW=STR$(R(D) 1398 BLANK=1B-LEN(NUM$) 1399 FOR L=l TO BLANK 1318 LIN*=LIN$+" " 1311 NEXT L 1312 LIN$=LINi+NUM$ 1313 NEXT I 1314 LPRINT LIN* 307 1315 1316 1317 LENSTH=LEN(LIN$) FOR 1=1 TO TMflX F$=* "+STRINGI(LENGTH,"-") 13ie NEXT I 1328 LPRINT F* 1321 ' 1322 1 PRINT DRAWDOWNS FOR TIME UD 1323 FOR 1=1 TO TMAX 1324 T(I)=T(I)/24/68/68 1325 TII€SMSTR$(T(D) 1326 BLANK=5-iEN(TII1ES*) 1327 TIWES$=SPACE$(BLANK)+TI«ES$ 1331 LIN*=* •+TI«ES*+" ' 1332 FOR J=l TO RMAX 1333 NUH$=STR*(H(I,J)) 1334 G$=" " 1335 PTjSI=INSTR(NUr1*,G$) 1336 P0SI=P0SI+2 1337 LNUW=MIW(NU»aiPOSI) 1338 BLANK=10-LEN(LNUM) 1348 FOR L=l TO BLANK 1345 LIN*=LIN*+" • 1358 NEXT L 1355 LIN$=LIN$+LMH» 1368 NEXT J 1365 LPRINT LIN* 1378 NEXT I 1372 LPRINT f^ (38),CHR$(27)mR$(ll)CHR$(48)CHR$(52) 1375 STOP 1368 END 1385 ' 1398 ' i i i i i i i i i i i i i i m i i i i i i i i i i i H i i i i i i i i i n i i i i i i i i i i i i i i i i i H i i i i i i i i i i i i i 1395 ' SUBROUTINE FACTORIAL 1488 ' i i i i i i i i i i i i i i i i i i i i i i i i u n i i i i i u m m n i m i m i m i i i i i n w t t w w 1485 'THIS SUBROUTINE CALCULATES THE FACTORIAL OF A NUMBER INPUT AS X AND 1418 'ASSIGNS THE RESULT TO VARIABLE FACT. VARIABLE COUNTER = II. 1415 FACT=1 1428 FOR 11=1 TO X 1425 FACT=FACT*II 1438 NEXT II 1435 RETURN 1436 ' 1448 ' i i i i i i m i n n i i i i i i i i i i u i i i i i i w i i n i m i i i i m n i i i i i i i i i i i i n n i i i m 1998 ' SUBROUTINE WSERIES 1331 ' ^ l^lBl^ ^^^^^^^^^^^^l^^i^^^^^^^^^^^^^m^^^^l '^t^ f '^^ t^l^ ^^^m^^^^l^^^^^^n^l^n 1992 'THIS SUBROUTINE EVALUATES THE WELL FUNCTION BY THE FIRST TEN TERMS OF AN 1993 'INFINITE TAYLOR SERIES FOR THE INTEGRAL 1994 LNAX=18 1999 UU#=U 2908 SUMf=L06(UUt) 2881 FOR L=l TO LNAI 2862 X=L 2883 GOSUB 1485 2884 TERN#=(-UUfAL)/(L»FACT) 2885 SLWt=SUMI+TERMt 2887 NEXT L 2808 W=-1.263298-SUBI+.56 2883 RETURN 2818 ; m l u m m u m i 3888 ' SUBROUTINE WSIMPSON 3805 1 I I I I I I I I I I I I I I I I H I t m U H I I I I I I U I I I I I I H H U I I I I H I i m i H H f H t l l l l l l l 3818 'THIS SUBROUTINE USES THE SIMPSON RULE TO EVALUATE THE WELL FUNCTION 3815 'INTEGRAL FOR VALUES OF U GREATER THAN 8.5 BECAUSE THE TAYLOR SERIES DOES 3828 'NOT CONVERSE RAPIDLY ABOVE 8.5. 3825 ' 3826 'DETERMINE SMALLEST UPPER BOUND FOR INTEGRAL TO INCREASE ACCURACY 3831 IF U (=3! THEN PHIGH=3! 3832 IF U (=3! THEN PINF=.813 3833 IF U (=6! THEN PHI6H=6! 308 3034 IF U (=6! THEN PINF=.00036 3035 IF U (=9! THEN PHIBH=9! 3036 IF U (=9! THEN PINF=. 3042 IF U (=9! SOTO 3888 3065 U=.000012 3066 GOTO 3200 3070 ' 3075 'EVALUATE THE INTEGRAL 3080 PL0W=U 3885 U1HX=100 3090 DEL=(PHIGH-PLOW)/(UfflX-l) 3095 SUR=0 3100 ODD=8 3105 EVEN=0 3110 X=PHIGH 3115 GOSUB 3230 3120 SUH=SUIHfX 3125 X=PLDW 3130 GOSUB 3230 3135 SUrt=SU!1+FX 3140 JJMAX=LMflX/2-l 3145 FOR JJ=1 TO JJUflX 3155 X=X+DEL 3160 GOSUB 3230 3165 EVEN=£VEN+fX 3178 X=X+DEL 3175 GOSUB 3230 3180 0DD=0DD+fX 3185 NEXT JJ 3190 SUM=Da/3*(SUH+4«ODD+2«EVEN) 3195 W=SU*+PINF 3200 RETURN 3205 ' 3210 ' I I I H I l l l H I I H I I I I I l l H i m H l l H l l l l l H H I I I I I l l l l l l l l l l l l l l l l l l l l l l l l l l 3215 ' SUBROUTINE FUNCTION 3220 ' i i i i i i i i i i u i i i i i i i i u i i i i i u i i i i i n i n m H m H H u m w i u i i i i n i m i i i i i m i 3225 'THIS SUBROUTINE EVALUATES THE FUNCTION TO BE INTEGRATED. 3230 FX=£XP(-X)/X 3235 RETURN 3248 ' 3245 ' i i i i i i i i i i i i i i i i i i i i i i i i i i i m i i i i i i i i i i i i i i i i i i i i i i H i i i i i i i i i i i i i i i i i i i i 309 J . l PIEZOMETER INSTALLATION This appendix d e s c r i b e s the method of piezometer i n s t a l l a t i o n used i n a l l piezometers completed i n 1984. Figure J . l i s a g e n e r a l i z e d i l l u s t r a t i o n of a completed piezometer, showing approximate dimensions of f i l l o btained u s i n g the f o l l o w i n g procedure: - check depth t o bottom of hole and record. - s l o w l y pour 3/4 of bucket o f pea g r a v e l - p e r f o r a t e bottom 1.0 m of 1" pvc pipe - glue up pipe t o s u f f i c i e n t l ength t o a l l o w 1.5 m s t i c k up - lower pipe down the ho l e , c a u t i o n p e r f o r a t e d s e c t i o n breaks e a s i l y - pour 1/2 bucket o f pea g r a v e l , shake pvc pipe c o n t i n u o u s l y w h i l e pouring - s l o w l y pour 1/2 bucket o f bentonite down hole - back f i l l h ole w i t h c u t t i n g s - cut o f f remaining p i p e , leave 1.5 m s t i c k up - i n s t a l l p r o t e c t i v e cover (see Figure J.2 f o r design) s/f MA ii} W »l »i \n AIR T R A C H O L E , 2-7/8" DIAM I" P V C PIPE PROTECTIVE COVER CASINO, 3" INNER DIAMETER o BENTONITE SEAL, o PERFORATED TIP o in P E A G R A V E L 310 LID DETAIL CUT 38 x 38 cn SQUARE HOLE POLISH EDS SO IT UILL NOT BE SHARP 45 GALLON DRUM TOP OF BARREL NOT USED 48 cn 2 cn 39 ca note: - 8 COVERS REQUIRED - PAINT BRIGHT RED FOR VISIBILITY - PAINT LIDS BLACK - LABEL BARRELS ON SIDES AS FOLLOWS: Pl-3, P4, P5, PE-, P7, P8, P9, Pig EQUITY SILVER MINES LTD. PIEZOMETER INSTALLATION COVER FIGURE J.2 J.2 PIEZOMETER LOCATION Piezometer Northing Easting Elevation Depth Pipe Number at Ground Stickup P01 8305.02 8715.83 1330.28 147.50 P02 II If II 61.80 P03 11 n n 38.20 P04 7663.43 8961.48 1358.99 P05 7475.67 8893.77 1377.28 23.50 1.00 P06 7523.34 8821.34 1339.52 26.50 0.60 P07 7686.51 8885.23 1340.18 28.00 0.90 P08 7505.50 8844.54 1359.88 26.90 1.00 P09 7343.36 8579.31 1340.33 P10 8028.30 8833.00 1320.09 P l l 8013.38 8887.08 1351.85 27.70 P12 8006.88 8929.90 1359.30 26.40 P13 8200.84 8837.02 1346.25 PI 4 8198.63 8914.05 1353.42 27.70 KOI 7612.50 8643.75 1280.00 9.00 K02 8119.06 8624.06 1318.55 151.49 312 J.3 PIEZOMETER MONITORING DATE PI P2 P3 P4 P5 PE P7 P8 P9 P10 Pll P12 Pi3 P14 84/05/14 17.60 18.65 25.30 84/05/30 13.35 15.23 21.36 10.21 84/06/87 13.60 17.38 23.13 18.61 84/06/12 13.83 18.29 23.91 11.52 84/06/18 14.10 19.63 25.51 14.38 84/06/25 21.50 21.54 27.41 18.96 84/07/04 14.92 22.93 28.82 17.82 34/07/28 16.62 24.70 31.05 18.86 84/07/30 17.93 26.44 32.23 20.84 84/08/17 19.46 27.52 27.08 22.81 84/08/30 18.10 24.20 23.60 19.35 15.80 15.35 17.50 18.20 27.18 84/89/86 16.70 10.50 15.80 16.55 6.58 PUMPING WELL DRAWDOWN SIMULATION PARAMETERS INFLUENCE OF HYDRAULIC CONDUCTIVITY 1.00E-04 cm/5 50. iZiiZ) rn 3. "250 10. iJiZl 1/min DRAWDOWN RESULTS TIME RADIAL POSITION (n) (days) 5 10 28 58 188 208 1 99.47 99.77 99.95 99.99 108.88 108.08 5 99.85 99.41 99.73 99.97 99.99 188.88 IB 98.87 99.23 99.58 99.98 99.99 188.88 58 98.45 98.81 99.18 99.63 99.88 99.99 108 98.26 98.63 99.08 99.47 99.77 99.95 38.38 98.45 98.81 99.29 99.63 99.88 538 57.84 9B.20 98.57 99.85 99.41 99.73 law 97.55 98.82 98.39 98.87 99.23 99.58 K THICK = SY O = PUMPING WELL DRAWDOWN SIMULATION PARAMETERS INFLUENCE OF HYDRAULIC CONDUCTIVITY K = 1 . 00E-05 crn/s THICK = 50. 130 m 5Y = 0. 050 Q = 10.00 1/min DRAWDOWN RESULTS TIME RADIOL POSITION (n) (days) 5 10 £0 50 100 200 1 99.09 99.% 99.99 99.99 99.99 99.99 5 96.33 98.80 99.31 99.99 99.99 99.99 18 94.78 97.74 99.56 99.99 99.99 99.99 58 90.59 94.15 97.33 99.72 99.99 99.99 188 88.77 92.39 95.82 99.09 99.96 99.99 2M 86.94 98.59 94.15 98.11 99.72 99.99 581 84.51 88.18 91.81 96.33 98.80 99.91 1008 82.68 86.35 98.88 94.78 97.74 99.56 315 PARAMETERS PUMPING WELL DRAWDOWN SIMULATION INFLUENCE OF HYDRAULIC CONDUCTIVITY K = 1. iZiiZiE-136 cm/5 THICK = 50. 00 m SY = 0.050 Q = 1 0 . 0 0 1/min DRAWDOWN RESULTS TIME RADIOL POSITION (a) (days) 5 10 20 50 100 200 1 99.99 99.99 99.99 99.99 99.99 99.99 5 97.22 99.98 99.99 99.99 99.99 99.99 10 90.95 99.61 99.99 99.99 99.99 99.99 50 63.39 88.86 99.17 99.99 99.99 99.99 188 47.03 77.49 95.67 99.99 99.99 99.99 238 29.63 63.39 68.06 99.84 99.99 99.99 500 5.91 41.51 73.32 97.22 99.98 99.99 1000 -12.28 21 90 58.29 90.95 99.61 99.99 PUMPING WELL DRAWDOWN SIMULATION PARAMETERS INFLUENCE OF nYDRAULIC CONDUCTIVITY K = 1 . 00E-07 cm/s THICK = 50. 0i2i rn SY = 0. 050 Q = 1 0 . 3 0 1/min DRAWDOWN RESULTS TINE RADIAL POSITION (•) (days) 5 10 20 50 100 200 1 99.99 99.99 99.99 99.99 99.99 99.99 5 99.99 99.39 99.99 99.99 99.99 99.99 18 99.97 99.99 99.99 99.99 99.99 99.99 58 72.23 99.37 99.39 99.99 99.99 99.99 100 9.59 96.13 99.99 99.99 99.99 99.99 £» -38.56 72.29 99.87 99.99 99.99 99.99 530 -266.06 -19.39 91.79 99.99 99.99 99.99 1000 -429.66 -125.87 56.79 99.97 99.99 99.99 317 PARAMETERS PUMPING WELL DRAWDOWN SIMULATION • INFLUENCE OF THICKNESS K = 1. 00E-05 cm/s THICK = 10. 0 0 rn SY = 0. 050 •a 10. 00 1 / rn i n DRAWDOWN RESULTS TIME RADIAL POSITION (a) (days) 5 10 20 50 100 200 1 99.92 99.99 99.99 99.99 99.99 99.99 5 35.47 99.80 99.99 99.99 99.99 99.99 10 90.57 98.61 99.99 99.99 99.99 99.99 50 73.51 88.74 37.83 99.99 99.99 99.99 100 64.81 81.69 94.03 99.92 99.99 99.99 200 55.86 73.51 88.74 99.17 99.99 99.99 500 43.85 61.95 79.14 95.47 99.80 99.99 1300 34.71 52.35 70.75 30.57 38.61 99.39 PARAMETERS PUMPING WELL DRAWDOWN SIMULATION INFLUENCE OF THICKNESS K = 1 . 130E-C5 cm/s THICK = £0. '210 m SY = 0. 050 Q = 1 0 . 0 0 1/min DRAWDOWN RESULTS TIME RADIAL POSITION (m) (days) 5 10 20 50 100 200 1 99.58 99.99 99.99 99.99 99.99 99.99 5 95.28 99.30 99.99 99.99 39.39 99.99 18 92.06 97.73 99.90 99.99 59.99 99.99 50 82.40 90.84 97.81 99.96 99.99 33.39 100 77.93 86.75 94.37 99.58 S9.99 - a zo 200 73.39 32.40 90.34 98.36 33.36 33.39 500 67.35 76.47 85.37 95.28 99.33 1000 62.77 71.92 30.97 92.06 97.73 . 39.30 PARAMETERS PUMPING WELL DRAWDOWN SIMULATION INFLUENCE OF THICKNESS 1. I30E-05 cm/s 50. 00 rn 0. 050 10. 00 i/min DRAWDOWN RESULTS TIME RADIAL POSITION (n) (days) C mj 19 29 50 100 209 1 59.03 99.96 99.99 99.99 99.99 99.99 5 36.33 98.80 39.91 99.39 99.33 •99.99 10 94.70 97.74 99.56 99.99 99.99 59.99 59 90.59 94.15 97.33 99.72 39.99 99.99 199 88.77 92.39 95.82 99.39 39.96 39.93 £09 86.94 90.59 94.15 38.11 53.72 33.33 590 54.51 68.18 91.81 96.33 98. SO 35.91 1090 82.68 86.35 90.00 94.70 97.74 59.56 K THICK = is 1 O PARAMETERS PUMPING WELL DRAWDOWN SIMULATION INFLUENCE OF THICKNESS K = 1 . 00E-IZI5 cm/3 THICK = HZiiZi. 00 m SY = iZi. 2150 Q = 1 0 . 0 0 1/min DRAWDOWN RESULTS TIME RADIAL POSITION (n) (days) 5 10 20 50 100 200 1 39.05 99.86 99.99 99.99 99.99 99.99 5 37.35 98.87 99.78 99.99 39.33 93.99 10 96.48 98.16 99.40 99.99 99.99 99.99 50 34.38 96.19 97.91 99.54 39.98 99.99 100 93.47 95.29 97.07 99.05 99.86 ce_ go 200 92.55 94.38 96.19 38.41 99.34 39.38 500 91.34 93.17 95.80 97.35 98.87 39.78 1000 90.42 92.25 94.99 96.48 98.16 99.40 3£1 PARAMETERS PUMPING WELL DRAWDOWN SIMULATION INFLUENCE OF SPECIFIC YIELD K = 1 . 00E-05 cm/s THICK = 50. U-13 rn SY = i3 . 010 Q = 10.0iZi 1/miri DRAWDOWN RESULTS TIME RADIAL POSITION Oil (days) 5 18 20 58 188 288 1 96.33 98.88 39.91 99.99 99.99 99.99 5 92.33 95.82 98.43 99.96 99.99 99.93 18 98.59 94.15 97.33 99.72 99.99 99.99 58 86.35 90.00 93.59 97.74 99.56 99.99 100 84.51 88.18 91.81 96.33 38.88 99.91 200 82.68 86.35 90.00 94.70 37.74 99.56 500 80.25 83.92 87.59 92.39 95.82 38.43 1000 78.41 82.08 85.76 90.59 94. 15 97.33 3£2 PUMPING WELL DRAWDOWN SIMULATION PARAMETERS K = 1.00E-05 cm/s THICK = 50.00 rn SY = 0.050 Q = 10.00 1/min DRAWDOWN RESULTS TIME RflDIRL POSITION (H) (days) 5 10 28 50 100 200 1 99.09 99.96 99.99 99.99 99.99 99.93 S 95.33 98.80 99.91 99.99 99.93 99.99 18 94.70 97.74 99.56 99.99 99.99 99.99 58 90.59 94.15 97.33 99.72 99.99 99.99 108 83.77 92.39 95.82 99.89 99.96 99.99 200 86.94 90.59 94.15 98.11 99.72 99.99 500 84.51 88.18 91.81 96.33 98.80 99.91 1000 82. G8 86.35 90.80 94.70 97.74 99.56 PUMPING WELL DRAWDOWN SIMULATION PARAMETERS K = 1 . 0 O E - 0 5 cm/s THICK = 50.00 m SY = 0.100 Q = 10.00 1/min DRAWDOWN RESULTS TIME RADIAL POSITION (a) (days) 5 10 29 59 100 290 1 99.72 99.99 99.99 99.99 99.99 99.99 5 97.74 99.56 99.99 99.99 99.99 99.99 l i 96.33 98.80 99.91 99.99 99.99 99.99 50 92.39 95.82 98.43 99.96 99.99 99.99 100 90.59 94.15 97.33 99.72 99.99 99.99 200 88.77 92.39 95.82 99.09 99.96 99.99 5S0 86.35 99.00 93.59 97.74 99.56 99.99 1008 84.51 88.18 91.81 96.33 98.89 99.91 3£4 PUMPING WELL INFLUENCE DRAWDOWN SIMULATION OF SPECIFIC YIELD K = 1. 00E-05 cm/s THICK = 50. 00 rn SY — 0. 300 D 10. 00 1/min DRAWDOWN RESULTS TIME RADIAL POSITION (a) (days) 5 :0 20 50 100 290 1 99.99 99.99 99.99 99.99 99.99 99.99 5 99.38 99.98 99.99 99.39 99.93 99.99 10 98.36 99.81 99.99 99.99 99.99 99.99 59 95.14 98.05 99.63 99.99 99.99 99.39 100 93.42 96.73 39.04 99.99 99.99 99.99 290 91.64 95.14 38.05 39.30 99.99 99.39 500 39.25 92.85 96.24 99.39 99.98 99.39 1000 87.42 91.06 34.69 98.36 99.81 99.99 3£5 PARAMETERS PUMPING WELL DRAWDOWN SIMULATION INFLUENCE OF SPECIFIC YIELD K = 1. 00E-05 cm/s THICK = 50. 00 rn SY 0. 050 Q = 10. 00 1 /miri DRAWDOWN RESULTS TIME SflDIAL POSITION (•) (days) 5 10 20 50 100 200 1 95.09 99.96 99.99 99.99 99.99 99.99 5 96.33 98.30 99.91 99.99 99.99 99.99 IB 94.70 97.74 99.56 99.99 99.99 99.99 50 90.59 94.15 97.33 99.72 99.99 99.99 100 88.77 92.39 95.82 99.09 99.96 99.99 m 86.94 90.59 94.15 98.11 99.72 93.99 500 84.51 8B.18 91.81 96.33 98.80 39.91 1000 32.68 86.35 90.00 94.70 97.74 99.56 PUMPING WELL DRAWDOWN 51MULAT I PARAMETERS INFLUENCE OF SPECIFIC YIELD K = 1.00E-05 cm/s THICK = 50. 00 m SY = 0. 300 0 10. 00 1 /min DRAWDOWN RESULTS TIME RADIAL POSITION (m) (days) 5 10 £0 50 100 209 1 99.99 59.99 99.99 99.99 99.99 99.99 5 99.30 99.98 99.99 93.39 99.39 99.99 10 98.36 99.81 99.99 99.99 93.99 39.99 50 95.14 38.35 33.63 99.99 99.39 99.39 100 33.42 96.73 99.04 99.99 99.99 99.39 £'30 91.64 35.14 38.35 39.30 39.99 99.39 500 39.25 92.85 36.24 99.30 99.98 99.39 1000 37.42 91.06 34.60 38.36 99.81 99.39 PARAMETERS PUMPING WELL DRAWDOWN SIMULATION INFLUENCE OF PUMPING RATE K 1. 00E-05 cm/s THICK = 50. 00 m SY 0. 050 Q 10. 00 1 /min DRAWDOWN RESULTS TIME RADIAL POSITION (a) (days) c 18 20 50 100 200 < 99.09 99.96 99.99 99.99 39.99 99.99 5 96.33 98.30 99.91 99.99 99.99 99.99 10 94.70 97.74 99.56 99.99 93.99 99.99 50 90.59 94.15 97.33 99.72 99.39 99.99 100 88.77 92.39 95.82 99.09 99.96 59.99 200 86.94 90.59 94.15 98.11 99.72 99.39 500 84.51 88.18 91.81 96.33 93.80 59.91 1000 32.68 86.35 90.00 94.70 97.74 99.56 328 PUMPING WELL DRAWDOWN SIMULATION PARAMETERS INFLUENCE OF PUMPING RATE K = 1.00E-05 cm/s THICK = 50. 00 rn SY — 0. 050 Q £0. 00 1 / m i n DRAWDOWN RESULTS TIME RADIAL POSITION (n) (days) 5 10 £0 50 100 208 i 38.19 59.92 99.99 99.99 99.99 99.99 5 92.67 97.61 99.83 99.99 99.99 99.99 10 89.40 95.49 99.13 99.99 99.99 99.99 50 81. IB 88.30 94.56 99.44 99.99 99.99 100 77.54 84.78 91.65 98.19 99.92 99.99 200 73.88 81.18 88.30 96.22 99.44 99.99 500 69.03 76.26 83.62 92.67 97.61 59.83 1000 65.36 72.70 80.81 89.40 95.49 99.13 PARAMETERS PUMPING WELL DRAWDOWN SIMULATION INFLUENCE OF PUMPING RATE K = 1 . 00E-05 cm/s THICK = 50.00 m SY = 0. 050 Q = 50. 00 l/.rniri DRAWDOWN RESULTS TIME RADIAL POSITION (•) (days) 5 10 20 59 100 208 1 95.47 99.80 99.99 99.99 99.99 99.99 5 81.69 94.03 99.58 39.99 99.99 99.99 Ifl 73.51 88.74 97.83 99.99 99.99 99.39 50 52.95 70.75 86.66 98.61 99.99 99.99 100 43.85 61.95 79.14 95.47 99.80 39.99 200 34.71 52.95 79.75 99.57 98.61 •39.99 300 22.58 40.91 59.97 81.69 94.03 99.58 1000 13.40 31.76 59.03 73.51 88.74 37.83 PUMPING WELL DRAWDOWN SIMULATION PARAMETERS INFLUENCE OF PUMPING RATE K = 1 . iZliZiE-05 cm/s THICK = 50. iZi© m SY = iZi. 050 Q = 100.00 l / m i n DRAWDOWN RESULTS TIME VIDIflL POSITION (•) (days) 5 10 20 50 100 200 1 90.95 99.61 99.99 99.99 99.99 39.99 5 63.39 38.06 99.17 99.99 99.99 33.99 10 47.03 77.49 95.67 99.99 99.99 39.99 50 5.91 41.51 73.32 97.22 99.98 99.39 100 -12.28 23.90 58.29 90.95 99.61 99.99 200 -30.57 5.91 41.51 81.14 97.22 39.98 508 -54.82 -18.16 18.14 63.29 88.06 99.17 1000 -73.IB -36.47 6.93 47.03 77.49 95.67 PUMPING WELL DRAWDOWN SIMULATION PARAMETERS K = 1.00E-04 cm/s THICK = 30.00 rn SY = 0.050 Q = 100.00 1/min DRAWDOWN RESULTS TIWE RADIAL POSITION (a) (days) 5 10 20 50 100 200 1 93.28 97.46 99.76 99.99 99.99 99.99 5 86.53 92.33 97.01 99.87 99.99 99.99 18 B3.52 89.48 94.93 99.33 99.99 99.99 58 76.45 82.54 88.54 95.68 99.01 99.98 103 73.39 79.50 85.56 93.20 97.46 99.76 203 70.32 76.45 82.54 90.42 95.68 99.01 580 65.28 72.40 78.52 86.53 92.33 97.01 1088 63.21 69.34 75.46 83.52 89.48 94.93 

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