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Empirical stope design at the Ruttan Mine, Sherritt Gordon Mines Ltd. Pakalnis, Rimas Thomas 1986

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EMPIRICAL STOPE DESIGN AT THE RUTTAN MINE, SHERRITT GORDON MINES LTD. by RIMAS THOMAS PAKALNIS B. E n g i n e e r i n g , M c G i l l U n i v e r s i t y , 1979 MASc, U n i v e r s i t y of B r i t i s h C o l u m b i a , 1982 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF • THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF MINING AND MINERAL PROCESS EURXNEERING 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 to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA A u g u s t , 1986 (£) Rimas P a k a l n i s , 1986 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an advanced degree a t t h e 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 , I agree t h a t t h e L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u rposes may be g r a n t e d by t h e head o f my department o r by h i s o r h e r r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f ri/AJ/A/C 8 ///^F/LrtL / / o c fc'^f CAJ<Z/? The U n i v e r s i t y o f B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 ABSTRACT T h i s t h e s i s e v a l u a t e s the f a c t o r s t h a t i n f l u e n c e the s t a b i l i t y of l a r g e , open s t o p e s f o r an e x i s t i n g m i n i n g o p e r a t i o n . The R u t t a n mine, a 6000 tpd base m e t a l o p e r a t i o n has mined by open s t o p i n g methods s i n c e 1979. T h i s has r e s u l t e d i n a l a r g e d a t a base of i n f o r m a t i o n which i n c l u d e s f o r t y - t h r e e (43) s t o p e s a t v a r i o u s s t a g e s of e x t r a c t i o n , t h e r e b y y i e l d i n g 133 o b s e r v a t i o n s o f : Rock Mass R a t i n g ( f o o t w a l l , h a n g i n g w a l l , o r e ) Stope D i m e n s i o n s ( h e i g h t , w i d t h , l e n g t h ) O b s e r v e d D i l u t i o n E x c a v a t i o n R a t e s Stope C o n f i g u r a t i o n ( i s o l a t e d , r i b , e c h e l o n ) M i n i n g Sequence/Method In a d d i t i o n , the o b s e r v a t i o n s were s u p p l e m e n t e d w i t h i n - s i t u measurements, s t r u c t u r a l mapping, s t r e s s and d e f o r m a t i o n m o n i t o r i n g and h i s t o r i c a l o b s e r v a t i o n . I t was c o n c l u d e d t h r o u g h n u m e r i c a l m o d e l l i n g , o b s e r v a t i o n and measurement t h a t the h a n g i n g w a l l and f o o t w a l l of the i n d i v i d u a l s t o p e s a r e i n a s t a t e of r e l a x a t i o n , t h e r e b y e n a b l i n g s t r u c t u r a l b l o c k s to be r e l e a s e d . T h i s would g e n e r a l l y be the c a s e f o r most s t o p e g e o m e t r i e s whose major i n - s i t u s t r e s s d i r e c t i o n l i e s p e r p e n d i c u l a r to the l o n g d i m e n s i o n of the o p e n i n g . C o n s e q u e n t l y the c r i t i c a l p a r a m e t e r s were q u a n t i f i e d i n terms i l l of t h e i r e f f e c t on d i l u t i o n by e m p l o y i n g m u l t i v a r i a t e a n a l y s i s . The r e l a t i o n s h i p s d e r i v e d were e n t i r e l y c o n f i n e d to the R u t t a n o p e r a t i o n as th e y were e m p i r i c a l l y d e l i n e a t e d and q u a n t i f i e d . The R u t t a n o p e r a t i o n Is a m u l t i - l e n s e d ocebody w i t h i n d i v i d u a l s t o p e s d i p p i n g a t 7 0 ° . The f o l l o w i n g e m p i r i c a l l y d e r i v e d r e l a t i o n s h i p s were f o u n d to c o r r e l a t e s t r o n g l y w i t h the o b s e r v e d d i l u t i o n : D i l . = P L A N i ISOLATED STOPES (61 o b s e r v a t i o n s ) F i g u r e 8.7a 8.6 - 0.09(RMR) - 1 3 . 2 ( E x p . R a t e ) + 0 . 0 0 3 8 ( A r e a Exp.) PLAN O i l , r - 0.79 s - i 3 Z PLAN • ECHELON STOPES (44 o b s . ) F i g u r e 8.7b 10.3 - 0.13(RMR) - 1 4 . 8 ( E x p . R a t e ) + 0 . 0 0 3 ( A r e a Exp.) r= 0.83 s»i2Z MSBM WB3M RIB STOPES (28 o b s . ) F i g u r e 8.7c D i l . - 15.8 - 0.18(RMR) - 7 . 7 ( E x p . R a t e ) + 0 . 0 0 2 6 ( A r e a Exp.) r - 0.80 s=*4Z where: D I L ( % ) - r e f e r s t o p r e d i c t e d s t o p e d i l u t i o n ( t o n s w a s t e / t o n s r e s e r v e s ) RMR(%) - Rock Mass R a t i n g of the c r i t i c a l w a l l c o n t a c t , g e n e r a l l y the h a n g i n g w a l l Exp. Rate('1000m 2/mth) - r e f e r s to the r a t e a t w h i c h the h a n g i n g w a l l i s e x p o s e d ( e x c a v a t i o n r a t e / s t o p e w i d t h ) Area(m^) - r e f e r s to the ex p o s e d s u r f a c e a r e a of the h a n g i n g w a l l i v r , s - r e f e r s to the c o r r e l a t i o n c o e f f i c i e n t and the u n b i a s e d s t a n d a r d e r r o r of e s t i m a t e r e s p e c t i v e l y The e m p i r i c a l r e l a t i o n s h i p s were r e l a t e d to s t o p e s mined s u b s e q u e n t to the s t u d y and y i e l d e d e r r o r s of e s t i m a t e (£) of p r e d i c t e d d i l u t i o n to w i t h i n 2 - 4% of the o b s e r v e d d i l u t i o n . The b l a s t i n d u c e d d i l u t i o n was s u b s e q u e n t l y added to the p r e d i c t e d d i l u t i o n . T h i s v a l u e i s d i f f i c u l t to e s t i m a t e and i s p r e s e n t l y r e c o r d e d as the d i l u t i o n t h a t i s o b s e r v e d as the s l o t ( i n i t i a l c u t ) i s b e i n g e x c a v a t e d . The d e s i g n e q u a t i o n s were based on a r e l a t i v e l y l a r g e d a t a base, c o n s i d e r i n g , t h a t the works of B i e n i a w s k i (1973) and B a r t o n (1974) were b a s e d on 49 and 200 cas e h i s t o r i e s r e s p e c t i v e l y . I t i s s u g g e s t e d t h a t the e m p i r i c a l methods of d e s i g n o u t l i n e d i n t h i s t h e s i s be a t t e m p t e d a t o t h e r o p e r a t i o n s where s t r u c t u r a l f a i l u r e i s the main f a c t o r c o n t r i b u t i n g to s t o p e d i l u t i o n . T h i s would augment the d a t a base and e x t e n d i t s a p p l i c a b i l i t y . P a r a m e t e r s u n i q u e to R u t t a n t h a t were employed i n e s t a b l i s h i n g the d a t a base a r e as f o l l o w s : h a n g i n g w a l l and f o o t w a l l of a l l s t o p e s a r e In r e l a x a t i o n g r o u n d w a t e r i s not a f a c t o r o o mean s t o p e i n c l i n a t i o n = 68 t 9 mean s t o p e d i l u t i o n = 10% - 6% mean RMR = 56% 1 20% mean e x p o s u r e r a t e = 0 . 18m 2 x.09m 2 (x 1000)/mth mean e x c a v a t i o n r a t e = 2700fipT 1300m^/tiith mean span = 31m t 13m mean s t o p e w i d t h = 15m- 3m mean s t o p e h e i g h t = 6 3m i 20m i^ean exposed s u r f a c e a r e a = 2250m -1120m 2 .loan s t o p e d e p t h = 360m i 48m below s u r f a c e mean b l a s t c o r r e c t i o n f a c t o r = 3% - 6% V TABLE OF CONTENTS PAGE ABSTRACT i i TABLE OF CONTENTS v LIS T OF TABLES v i i i L I ST OF ILLUSTRATIONS i x ACKNOWLEDGEMENTS x i v CHAPTER ONE INTRODUCTION 1.0 I n t r o d u c t i o n 1 CHAPTER TWO THE RUTTAN MINE 2.1 I n t r o d u c t i o n 8 2.2 G e o l o g y of the R u t t a n D e p o s i t 9 2.2.1 L o c a l G e o l o g y 11 2.3 Geometry of Orebody 13 2.4 M i n i n g P r a c t i c e 15 2.4.1 S t o p i n g Method 16 2.5 O b s e r v a t i o n s / C o n c l u s i o n s 19 CHAPTER THREE STOPE DESIGN METHODOLOGY 3.1 I n t r o d u c t i o n 33 3.2 L i t e r a t u r e Review 33 3.3 D e s i g n P h i l o s o p h y 33 3.4 Su r v e y of Open S t o p e O p e r a t o r s 42 3.4.1 Mine P r o f i l e 43 3.4.2 Rock M e c h a n i c s 45 3.4.2.1 Stope and P i l l a r D e s i g n 46 3.4.3 D i l u t i o n A s s e s s m e n t 48 3.4.4 Stope C h a r a c t e r i z a t i o n 49 3.4.4.1 S t o p e A s s e s s m e n t 51 3.4.4.2 P i l l a r A s s e s s m e n t 53 3.4.5 O b s e r v a t i o n s 54 3.5 C o n c l u s i o n s ^ v i CHAPTER FOUR STRESS 4.1 I n t r o d u c t i o n 73 4.2 I n - S i t u S t r e s s e s a t R u t t a n 74 4.2.1 S t r u c t u r a l I n t e r p r e t a t i o n 75 4.2.2 P r e v i o u s Measurements 76 4.2.3 V i r g i n S t r e s s Measurement 77 4.2.3.1 D i s c u s s i o n of R e s u l t s ^9 4.2.4 O b s e r v a t i o n s 8 0 4.3 S t r e s s C o n f i g u r a t i o n 8 2 4.3.1 N u m e r i c a l Code 8 2 4.3.2 P a r a m e t r i c S t u d y 4.3.2.1 V e r i f i c a t i o n of 3D-Model 4.3.2.2 O b s e r v a t i o n a l A p p r o a c h 4.4 C o n c l u s i o n 84 89 95 97 CHAPTER FIVE ROCK MASS CHARACTERIZATION 5.1 I n t r o d u c t i o n 121 5.2 Rock Mass C l a s s i f i c a t i o n 121 5.2.1 G e o m e c h a n i c s C l a s s i f i c a t i o n 126 5.3 Rock Mass 127 5.3.1 F a b r i c A n a l y s i s 132 5.4 K i n e m a t i c A n a l y s i s 134 5.5 O b s e r v a t i o n s / C o n c l u s i o n s 135 CHAPTER SIX DILUTION 6.1 I n t r o d u c t i o n 153 6.2 D e f i n i t i o n 153 6.3 O b s e r v e d D i l u t i o n 1=7 6.3.1 Volume Trammed Vs Stope D i m e n s i o n s Mined v i i CHAPTER SEVEN DATA BASE 7.1 I n t r o d u c t i o n 163 7.2 S t a t i s t i c s 1 6 4 7.2.1 D e f i n i t i o n of S t a t i s t i c a l Terms 1 6 6 7.3 D i s t r i b u t i o n of Data Base 1 7 2 7.4 I d e n t i f i c a t i o n of C r i t i c a l P a r a m e t e r s 178 7.4.1 P a r t i a l C o r r e l a t i o n 1 8 6 7.5 Q u a d r a t i c / L i n e a r I n t e r p r e t a t i o n 187 7.6 O b s e r v a t i o n s / C o n c l u s i o n s 188 CHAPTER EIGHT STOPE DESIGN 8.1 I n t r o d u c t i o n 213 8.2 Stope C o n f i g u r a t i o n 213 8.3 B l a s t C o r r e c t i o n F a c t o r 215 8.4 P r e d i c t i v e E q u a t i o n 216 CHAPTER NINE APPLICATION 9.1 I n t r o d u c t i o n 226 9.2 C a l i b r a t e d D a t a Base 226 9.3 O t h e r Methods 227 CHAPTER TEN CONCLUDING REMARKS 10.1 C o n c l u d i n g Remarks 239 LIST OF REFERENCES APPENDIX I - QUESTIONAIRE APPENDIX I I - RMR SYSTEM OF CLASSIFICATION 242 251 255 v i i i LIST OF TABLES TABLE PAGE 3 . 1 C l a s s i f i c a t i o n Systems - A p p l i c a t i o n s 59 3 . 2 L i m i t a t i o n s of the M a j o r Rock Mass Systems 59 3 .3 Summary of P a r a m e t e r s Employed 60 3 .4 Q u e s t i o n a i r e - P a r t i c i p a t i n g M i n i n g O p e r a t i o n s 61 3 .5 Q u e s t i o n a i r e - Open Stope M i n i n g O p e r a t o r s ( S t o p e ) 62 3 .6 Q u e s t i o n a i r e - Open Stope M i n i n g O p e r a t o r s ( P i l l a r ) 63 4 . 1 N u m e r i c a l Code 99 5 . 1 Core L o g g i n g Format - R u t t a n 136 5 . 2 I n t a c t Rock S t r e n g t h P a r a m e t e r s 137 5 . 3 Summary of Rock Mass P a r a m e t e r s 137 7 . 1 L e v e l s of S i g n i f i c a c e 189 7 . 2 Data Base 190 7 .3 S t a t i s t i c a l Mean - Data Base 192 7 .4 RMR - I s o l a t e d Stope 193 7 .5 C o m p a r i s o n Q u a d r a t i c / L i n e a r 194 8 . 1 C o m p a r i s o n P r e d i c t e d / O b s e r v e d - I s o l a t e d 218 8 . 2 C o m p a r i s o n P r e d i c t e d / O b s e r v e d - E c h e l o n 219 8 . 3 C o m p a r i s o n P r e d i c t e d / 0 b s e r v e d - R i b 219 9 . 1 S t o p e s Mined S u b s e q u e n t to S t u d y 232 9 . 2 C a l i b r a t e d Data Base - P r e d i c t e d D i l u t i o n 233 9 . 3 Augmented R i b Data Base . 233 I i x LIST OF ILLUSTRATIONS FIGURE PAGE 2.1 L o c a t i o n Map 22 2.2 L o n g i t u d i n a l of R u t t a n Mine 23 2.3 R e g i o n a l G e o l o g y 23 2.4 I s l a n d A r c Development 24 2.5 F o r m a t i o n of R u t t a n D e p o s i t 24 2.6 T e c t o n i c E v o l u t i o n 25 2.7 I s o m e t r i c Diagram - R u t t a n D e p o s i t 25 2.8 L o c a l G e o l o g y 26 2.9 P l a n of Ore L e n s e s - 260m L e v e l 26 2.10 T y p i c a l S e c t i o n - 2650E 27 2.11 Ore D e l i n e a t i o n P a t t e r n 27 2.12 I s o m e t r i c - 320m L e v e l 28 2.13 T y p i c a l S tope Geometry 28 2.14 S t o p i n g Method 29 2.15 Sequence of E x t r a c t i o n ( C o n v e n t i o n a l ) 30 2.16 Sequence of E x t r a c t i o n (ITH) 31 2.17 C a t e g o r i z a t i o n of Stope Geometry 32 3 . 1 Beam T h e o r y 64 3.2 V o u s s o i r A r c h 64 3.3 N u m e r i c a l S o l u t i o n 64 X 3 .4 Mathews Method of Stope D e s i g n 65 3 .5 H a n g i n g and F o o t W a l l Beam D e f l e c t i o n 65 3 .6 S t r e s s T r a j e c t o r i e s - 320m L e v e l 66 3 .7 S t r u c t u r a l l y C o n t r o l l e d F a i l u r e 66 3 .8 A d j a c e n t S t o p e s - P i l l a r F a i l u r e 67 3 .9 Mine P r o d u c t i o n - S i z e 68 3 . 10 D i s t r i b u t i o n of M i n i n g Method 68 3 .11 D i s t r i b u t i o n of M i n i n g Depth 68 3 .12 Rock S t r e n g t h P a r a m e t e r s 69 3 . 13 S t r e s s I n v e s t i g a t i o n s 69 3 .14 Rock Mass I n v e s t i g a t i o n s 69 3 . 15 Methods of D e s i g n 69 3 .16 Stope D i l u t i o n 70 3 .17 Rock Mass R a t i n g 70 3 .18 Ground C o n t r o l P r o b l e m s - Open Stope 70 3 . 19 Open S t o p e D i m e n s t i o n s 71 3 .20 F i l l U t i l i z a t i o n 72 3 .21 P i l l a r D i m e n s i o n s 72 4 . 1 F r a c t u r e P a t t e r n - C r u s h i n g 100 4 .2 F o l i a t i o n O r i g i n 100 4 .3 V e r t i c a l S t r e s s w i t h Depth 101 4 .4 H o r i z o n t a l S t r e s s w i t h Depth 101 4 . 5 S t r e s s Measurement L o c a t i o n 10 2 4 .6 CSIRO R e s u l t s 10 2 4 . 7 CSIRO T e s t #2 103 4 .8 S t r e s s D i r e c t i o n s - C a n a d i a n S h i e l d 103 x i 4 . 9 T a n g e n t i a l H a n g i n g W a l l S t r e s s Vs. Span/Width 104 4. 10 H o r i z o n t a l / V e r t i c a l S t r e s s R a t i o (k) 104 4. 11 T a n g e n t i a l H a n g i n g W a l l S t r e s Vs. Span/Width 104 4. 12 P a r a m e t r i c S t u d y - S t r e s s C o n f i g u r a t i o n 105 4 . 13 L a t e r a l E x t e n t of T e n s i l e Zone 106 4 . 14 R e l a t i o n s h i p - D i l u t i o n and T e n s i l e Zone 106 4 . 15 i R e l a t i o n s h i p - "k" on T a n g e n t i a l S t r e s s e s 107 4 . 16 L a t e r a l E x t e n t of T e n s i l e Zone Vs. "k" 107 4. 17 S t r e s s C o n f i g u r a t i o n - R i b S t o p e s 108 4 . 18 S t r e s s C o n f i g u r a t i o n - E c h e l o n S t o p e s 108 4. 19 V a r i a t i o n of T a n g e n t i a l S t r e s s - Number of O p e n i n g s 109 4 . 20 V a r i a t i o n of L a t e r a l E x t e n t - Number of O p e n i n g s 110 4 . 21 Base Case - S t r e s s C o n f i g u r a t i o n 110 4. 22 I n f l u e n c e of End E f f e c t s 111 4. 23 M o d e l l e d S t o p e s - Mt. I s a Mines 111 4 . 24 3 D - M o d e l l e d S t o p e 112 4. 25 E x t e n t of T e n s i l e Zone - H o r i z o n t a l P l a n e 113 4 . 26 E x t e n t of T e n s i l e Zone - V e r t i c a l P l a n e 113 4 . 27 R e l a x e d Zone " x z " and "xy" P l a n e 114 4 . 28 S u r f a c e E l e m e n t s i n R e l a x a t i o n 114 4 . 29 M i n i n g Sequence - 400m L e v e l 115 4 . 30 I r a d Gauge 6NS - F o o t W a l l 1 9 J 116 4. 31 I r a d Gauge 3EW - Fo o t W a l l 14D 116 4 . 32 E x t e n s o m e t e r i n F o o t W a l l of 13D 117 4 . 33 M o d e l l e d Sequence of E x t r a c t i o n 118 4 . 34 S t r e s s Change Vs. E x t r a c t i o n S t a g e 118 x i i 4.35 P h o t o g r a p h - R e l a x a t i o n 1 2 0 5.1 Stope C h a r a c t e r i z a t i o n 138 5.2 D i s t r i b u t i o n of Rock Types 139 5.3 H a n g i n g W a l l Rock Mass P a r a m e t e r s 140 5.4 Rock Mass D i s t r i b u t i o n 142 5.5 T y p i c a l RMR S e c t i o n s 143 5.6 T y p i c a l RMR P l a n s 144 5.7 S t e r e o n e t - T o t a l S t r u c t u r e s a t R u t t a n 146 5.8 S t e r e o n e t - "C L e n s " 260m L e v e l 146 5.9 P o l e C o n c e n t r a t i o n s - A l l L e v e l s 147 5.10 P h o t o g r a p h - M a j o r S e t s 148 5.11 P h o t o g r a p h - C o n t i n u i t y 149 5.12 Dominant J o i n t S e t s 150 5.13 T o p p l i n g 151 5.14 P o t e n t i a l F a i l u r e P l a n e s 151 5.15 Base F r i c t i o n Model 152 6.1 S e c t i o n D e f i n i n g D i l u t i o n 160 6.2 O b s e r v e d D i l u t i o n Vs. Volume E x c a v a t e d 160 6.3 Volume Trammed 161 6.4 L o n g i t u d i n a l 161 6.5 I n f e r r e d Span 162 7.1 S c a t t e r Diagram 195 7.2 S t a n d a r d E r r o r of E s t i m a t e 195 7.3 D i s t r i b u t i o n of S tope Data Base 196 7.4 H y d r a u l i c R a d i u s 197 7.5 S l o t E x c a v a t i o n - S t r e s s 197 x i i i 7 .6 Stope D i l u t i o n - "BCF" 198 7 .7 H i s t o g r a m s - D i s t r i b u t i o n of I s o l a t e d Data Base 199 7 .8 H i s t o g r a m s - D i s t r i b u t i o n of R i b Data Base 204 7 .9 H i s t o g r a m s - D i s t r i b u t i o n of E c h e l o n Data Base 206 7 . 10 C r i t i c a l P a r a m e t e r s 208 7 . 11 Rock Mass A n a l y s i s 209 7 .12 C r i t e r i a f o r S e n s i t i v i t y 209 7 . 13 G o v e r n i n g E q u a t i o n - D e r i v a t i o n f o r I s o l a t e d S t o p e s 210 7 .14 G o v e r n i n g E q u a t i o n - D e r i v a t i o n f o r E c h e l o n S t o p e s 210 7 . 1'5 S e n s i t i v i t y A n a l y s i s 211 7 .16 P a r t i a l C o r r e l a t i o n 211 7 .17 C o m p a r i s o n Q u a d r a t i c / L i n e a r 212 7 .18 Q u a d r a t i c / L i n e a r - I s o l a t e d S tope 212 8 . 1 G o v e r n i n g E q u a t i o n s 220 8 . 2 Stope C o n f i g u r a t i o n - A l l S t o p e s 221 8 .3 Stope C o n f i g u r a t i o n - Combined C o n f i g u r a t i o n s 221 8 .4 H y d r a u l i c and Span D e r i v a t i o n 222 8 . 5 I n c o r p o r a t i n g B l a s t C o r r e c t i o n F a c t o r 222 8 .6 D e l e t i n g B l a s t C o r r e c t i o n F a c t o r 223 8 . 7 P r e d i c t e d Vs. R e c o r d e d d i l u t i o n 223 8 .8 T e s t f o r Normal D i s t r i b u t i o n 225 9 . 1 Augmented Data Base 234 9 . 2 E m p i r i c a l D e s i g n - Mathews 235 9 .3a L a u b s c h e r Method of Span P r e d i c t i o n 237 9 .3b "Q" Method of Span P r e d i c t i o n 237 9 9 . 3c .4 "RMR" Method of Span P r e d i c t i o n V o u s s o i r Beam Method of Span P r e d i c t i o n 236 238 x i v ACKNOWLEDGEMENTS The a u t h o r would l i k e to e x p r e s s h i s a p p r e c i a t i o n to the management of R u t t a n Mine f o r p r o v i d i n g a s s i s t a n c e , d a t a , a c c e s s to i t s m i n i n g f a c i l i t i e s , f i n a n c i a l s u p p o r t and r e v i e w of the m a n u s c r i p t . S p e c i a l g r a t i t u d e i s e x t e n d e d to Todd M a d i l l and B e r n i e H a y s t e a d of the G e o l o g y Department a t R u t t a n f o r p r o v i d i n g g u i d a n c e and d i r e c t i o n . The a u t h o r would l i k e to thank P r o f e s s o r H.D.S. M i l l e r f o r p r o v i d i n g the at m o s p h e r e of l e a r n i n g , t h a t he has h e l p e d c r e a t e i n the f i e l d of u n d e r g r o u n d r o c k m e c h a n i c s a t the U n i v e r s i t y of B r i t i s h C o l u m b i a . H i s g u i d a n c e , encouragement and c o n s t r u c t i v e c r i t i c i s m t h r o u g h o u t the s t u d y was g r e a t l y a p p r e c i a t e d . The a u t h o r i s i n d e b t e d to h i s committee members , Mr. A l l a n Moss, Dr. Ross Hammett, P r o f e s s o r C.O. Brawner and Dr. George P o l l i n g f o r p r o v i d i n g i n v a l u a b l e g u i d a n c e t h r o u g h o u t the s t u d y . Thanks i s e x t e n d e d to Mr. Yves P o t v i n f o r a s s i s t a n c e i n c o n d u c t i n g p a r t s of the s t u d y . The w r i t e r w i s h e s to ack n o w l e d g e the d e v o t e d s u p p o r t of h i s w i f e , Anna, p a r t i c u l a r l y d u r i n g the f i n a l two months. T h i s t h e s i s i s d e d i c a t e d to Mrs. H e l e n P a k a l n i s . 1 CHAPTER ONE INTRODUCTION 1.0 I n t r o d u c t i o n T h i s t h e s i s i s the c u l m i n a t i o n of t h r e e y e a r s of s t u d y b o t h on s i t e a t the R u t t a n Mine of S h e r r i t t Gordon Mines L t d . and a t the U n i v e r s i t y of B r i t i s h C o l u m b i a . The o b j e c t i v e of t h i s t h e s i s i s to d e l i n e a t e and to q u a n t i f y the f a c t o r s t h a t i n f l u e n c e the s t a b i l i t y of l a r g e , open s t o p e s f o r an e x i s t i n g m i n i n g o p e r a t i o n . T h i s t h e s i s w i l l a s s e s s the g o v e r n i n g h y p o t h e s i s t h a t the "Optimum S t o p e Geometry" can be q u a n t i f i e d i n terms of the r o c k q u a l i t y , the e x t r a c t i o n r a t e and the exposed s u r f a c e a r e a . Optimum i s d e f i n e d as t h a t s t o p e geometry t h a t would y i e l d a m i n i m a l a c c e p t a b l e d i l u t i o n . D i l u t i o n i s a measure of the q u a l i t y of the d e s i g n s i n c e i t r e c o r d s the amount of h a n g i n g w a l l a n d / o r f o o t w a l l s l o u g h w i t h r e s p e c t to the s t o p e r e s e r v e s e x p e c t e d to be removed. The R u t t a n Mine, a 6000 tpd u n d e r g r o u n d o p e r a t i o n , i s l o c a t e d In N o r t h e r n M a n i t o b a , 760 km-, n o r t h of W i n nipeg and 20 km e a s t of the town of L e a f R a p i d s . The R u t t a n c o p p e r - z i n c orebody i s a m u l t i - l e n s e d , s t e e p l y d i p p i n g (70 ) en e c h e l o n d e p o s i t . I n d i v i d u a l l e n s e s have a maximum s t r i k e l e n g t h of 350m w i t h w i d t h s v a r y i n g from 7 to 61m. The m i n i n g method i s open s t o p i n g w i t h d e l a y e d b a c k f i l l i n g w h i c h e x t e n d s from s u r f a c e to 2 860 m below s u r f a c e . S t o p e spans a t the R u t t a n Mine were i n i t i a l l y d e s i g n e d e m p l o y i n g c l a s s i c a l beam t h e o r y . F a i l u r e s a t the mine were f o u n d to be c o n t r o l l e d p r i m a r i l y by s t r u c t u r e , and t h i s c o u l d n o t be e x p l a i n e d by the p r e v i o u s homogeneous model. There e x i s t s no a c c e p t e d d e s i g n method of p r e d i c t i n g s t o p e spans In j o i n t e d m a t e r i a l s . Beam t h e o r i e s , n u m e r i c a l models and e m p i r i c a l c r i t e r i a have been employed i n the p a s t w i t h some degr e e of s u c c e s s , however, the major drawback i s t h a t many of our c l a s s i c a l d e s i g n a p p r o a c h e s have been based on the a s s u m p t i o n t h a t homogeneous, i s o t r o p i c , e l a s t i c c o n d i t i o n s do e x i s t . F o r t y - t h r e e (43) s t o p e s a t the R u t t a n o p e r a t i o n were a n a l y z e d i n terms of the h y p o t h e s i s s t a t e d p r e v i o u s l y . T h i s d a t a base r e p r e s e n t s 432 s t o p e g e o m e t r i e s and r e s u l t a n t d i l u t i o n s as r e c o r d e d by the mine. The p r e v a i l i n g s t r e s s c o n d i t i o n s a t R u t t a n c a u s e the h a n g i n g wall(HW) and f o o t w a l l ( F W ) to be i n a r e l a x e d s t a t e . T h i s i s an i m p o r t a n t addendum to the above s t a t e m e n t of h y p o t h e s i s , s i n c e the e f f e c t on d i l u t i o n from s t r e s s i n d u c e d f a i l u r e and the c o n f i n e m e n t of i n d i v i d u a l s t r u c t u r a l b l o c k s i s e l i m i n a t e d . I t has been shown by Brady and Brown (1985) t h a t a c o n f i n i n g s t r e s s w i l l r e t a i n b l o c k s t h a t would o t h e r w i s e s l o u g h i n t o an o p e n i n g . I t i s not a t t e m p t e d i n t h i s t h e s i s to q u a n t i f y the c r i t i c a l c o n f i n e m e n t s i n c e s t o p e w a l l s a t R u t t a n w i l l be shown to be w i t h i n a zone of r e l a x a t i o n . The g o v e r n i n g h y p o t h e s i s w i l l be e m p i r i c a l l y d e v e l o p e d g i v e n the R u t t a n d a t a b a s e . 3 The c a s e s i n v o l v e d a t R u t t a n a r e f o r t h a t p a r t i c u l a r s t r e s s regime w h i c h c a u s e s the rock, mass i n the v i c i n i t y of the O r e c o n t a c t s to be i n a s t a t e of r e l a x a t i o n . The term "zone of r e l a x a t i o n " i s employed r a t h e r t han a zone of t e n s i o n . W h i l e i t i s t r u e t h a t t h i s r e g i o n i s u n c o n f i n e d , i t may not be i n pure t e n s i o n . The r e a s o n b e i n g t h a t i n o r d e r f o r t e n s i l e s t r e s s e s to be s u s t a i n e d i n the r o c k mass , the r o c k mass must have a t e n s i l e s t r e n g t h w h i c h i s g e n e r a l l y assumed to be non e x i s t e n t . An ore c o n t a c t t h a t i s i n a h i g h s t a t e of s h e a r or c o m p r e s s i o n w i l l r e s u l t i n e n t i r e l y d i f f e r e n t f a i l u r e modes. The d e v i a t i o n s t h a t may o c c u r from the R u t t a n d a t a base w i l l be a d d r e s s e d and d i s c u s s e d , however, the t h e s i s w i l l g e n e r a l l y be a p p l i c a b l e o n l y to a R u t t a n t y p e s i t u a t i o n whereby: - h a n g i n g w a l l and f o o t w a l l of an i n d i v i d u a l s t o p e i s In a r e l a x e d s t a t e - s t o p e p l u n g e r a n g e s between 60-70 d e g r e e s - s t o p e i s n o t choke b l a s t e d i e . s t o p e i s v o i d e d p r i o r to b l a s t i n g n e x t c u t T h i s t h e s i s i s d i v i d e d i n t o r e l e v a n t c h a p t e r s w h i c h by t h e m s e l v e s can s t a n d a l o n e , however, they a r e u l t i m a t e l y i n c o r p o r a t e d i n t o a c o h e s i v e u n i t i n f o r m u l a t i n g the s o l u t i o n to a c c e p t or r e j e c t the s t a t e d h y p o t h e s i s . The c h a p t e r s a r e as f o l l o w s : A) The R u t t a n Orebody: T h i s i s a g e n e r a l c h a p t e r 4 s u m m a r i z i n g the ore g e o m e t r y , l i t h o l o g y , s t o p e c o n f i g u r a t i o n , m i n i n g method and h i s t o r y . B) Stope D e s i g n M e t h o d o l o g y : T h i s c h a p t e r o u t l i n e s the c o m p l e x i t y of the R u t t a n d e p o s i t w i t h r e s p e c t to a r r i v i n g at a m e t hodology f o r s t o p e d e s i g n . I t a l s o summarizes a l i t e r a t u r e s e a r c h t h a t a s s e s s e s the s t a t e of the a r t of a ) s t o p e d e s i g n i n j o i n t e d m a t e r i a l s and b ) o f e x i s t i n g rock, mass c l a s s i f i c a t i o n s y s t e m s . A s u r v e y c o n d u c t e d by the a u t h o r which r e v i e w s the p r e s e n t s t a t e of s t o p e d e s i g n as i s p r a c t i c e d by open s t o p e o p e r a t o r s t h r o u g h o u t Canada i s summarized. T h i s q u e s t i o n n a i r e was s e n t to a l l C a n a d i a n base m e t a l open s t o p e and room and p i l l a r o p e r a t o r s whose p r o d u c t i o n e x c e e d e d 1000 t p d . A 58% r e s p o n s e was a c h i e v e d w h i c h r e p r e s e n t e d twenty-two (22) m i n e s , f i f t e e n (15) of w h i c h p r a c t i s e d open s t o p i n g methods. T h i s s u r v e y was c o n d u c t e d i n o r d e r t o a s s e s s the p r e s e n t s t a t e of s t o p e d e s i g n i n C a n a d i a n o p e r a t i o n s . C) S t r e s s : T h i s c h a p t e r a s s e s s e s the i n f l u e n c e of s t r e s s on the s t o p e g e o m e t r i e s a t R u t t a n . I n d i v i d u a l s t o p e s a r e m o d e l l e d by e m p l o y i n g a two d i m e n s i o n a l "boundary e l e m e n t " n u m e r i c a l code and a p o s t - p r o c e s s o r d e v e l o p e d f o r t h i s s t u d y . Nomograms are employed i n e s t i m a t i n g the s t r e s s e s g i v e n a p a r t i c u l a r s t o p e l e n g t h / w i d t h d i m e n s i o n . A two d i m e n s i o n a l a n a l y s i s i s employed and compared to o b s e r v a t i o n a l and q u a n t i f i a b l e measurements made t h r o u g h o u t the mine. A t h r e e 5 d i m e n s i o n a l b o u n d a r y e l e m e n t p r o g r a m , m o d i f i e d f o r t h e R u t t a n o p e r a t i o n , c o m p a r e s t h e v a l i d i t y o f m o d e l l i n g s t o p e s a t R u t t a n b y t h e 2D p r o c e s s . T h i s c h a p t e r d e s c r i b e s a m e t h o d i c a l a p p r o a c h t o t h e e s t i m a t i o n o f t h e i n - s i t u s t r e s s e s a t R u t t a n . T h e r e s u l t s w e r e s u b s e q u e n t l y v e r i f i e d by c o n d u c t i n g CSIRO h o l l o w i n c l u s i o n o v e r c o r i n g m e a s u r e m e n t s . D) R o c k M a s s A s s e s s m e n t : T h e R u t t a n o p e r a t i o n , i n c l u d i n g a l l f o r t y - t h r e e ( 4 3 ) s t o p e s , h a s b e e n a s s e s s e d i n t e r m s o f a s u i t a b l e r o c k m a s s d e s c r i p t o r . A s e l e c t i o n o f t h e m o s t s u i t a b l e c l a s s i f i c a t i o n w a s c h o s e n u p o n i d e n t i f y i n g t h e r e l e v a n t r o c k q u a l i t y p a r a m e t e r s w i t h r e s p e c t t o t h e R u t t a n d a t a b a s e . T h e m o s t c r i t i c a l p a r a m e t e r s w e r e e v a l u a t e d i n t e r m s o f r e s u l t a n t d i l u t i o n . T h i s i s t h e "control" p a r a m e t e r t h a t w i l l e n a b l e t h e h y p o t h e s i s t o be q u a n t i f i a b l y a s s e s s e d . A l l d e v e l o p m e n t a r e a s , m i n e d s t o p e s a n d f u t u r e m i n i n g a r e a s w e r e a s s e s s e d a R o c k M a s s R a t i n g . E ) D i l u t i o n : T h i s p a r a m e t e r i s a m e a s u r e o f t h e q u a l i t y o f t h e s t o p e d e s i g n . I t i s a p a r a m e t e r t h a t i s r e c o r d e d by m o s t o p e n s t o p e o p e r a t o r s i n C a n a d a ( Q u e s t i o n n a i r e , 1 9 8 5 ) . I t i s a m e a s u r e o f t h e d e g r e e o f w a l l s l o u g h w i t h r e s p e c t t o t h e e x p e c t e d s t o p e r e s e r v e s m i n e d . V a r i o u s d e f i n i t i o n s e x i s t a n d a r e s u m m a r i z e d i n t h i s c h a p t e r . T h e s e d e f i n i t i o n s a r e d e r i v e d f r o m t h e s u r v e y c o n d u c t e d p r e v i o u s l y . D i l u t i o n i s r e c o r d e d f o r a l l m i n e d s t o p e s a t R u t t a n a t v a r i o u s s t a g e s o f e x t r a c t i o n . 6 These a r e s t a t i s t i c a l l y c o r r e l a t e d to the r o c k q u a l i t y p a r a m e t e r s i d e n t i f i e d as c r i t i c a l . I t w i l l form the t e s t f o r h y p o t h e s i s a c c e p t a n c e or r e j e c t i o n . D i l u t i o n i s a q u a n t i f i a b l e a s s e s s m e n t of s t o p e d e s i g n , h o w e v e r i t i s a s s e s s e d i n most i n s t a n c e s by o b s e r v a t i o n . F) Data B ase: Upon the a s s e s s m e n t of the s i g n i f i c a n t f a c t o r s a f f e c t i n g d i l u t i o n , a d a t a base i s d e r i v e d f o r the i n d i v i d u a l mined s t o p e s a t R u t t a n . The d a t a base i s c o m p r i s e d of s t o p e d i m e n s i o n s ( s p a n , h e i g h t , w i d t h ) , s t o p e c o n f i g u r a t i o n , s t o p e d e p t h , i n c l i n a t i o n , e x t r a c t i o n r a t e , r e s u l t a n t r e c o r d e d d i l u t i o n , r o c k mass r a t i n g of the c r i t i c a l w a l l c o n t a c t , and o b s e r v e d damage due to b l a s t i n g . T h i s d a t a base i s c o m p r i s e d of 43 mined s t o p e s y i e l d i n g 432 r e c o r d e d s t o p e g e o m e t r i e s w h i c h were s u b s e q u e n t l y a v e r a g e d i n t o 133 c a s e h i s t o r i e s . G) Stope D e s i g n A s s e s s m e n t : The b e s t f i t p a r a m e t e r s a r e i n c o r p o r a t e d t h r o u g h s i n g l e / m u l t i p l e c o r r e l a t i o n t e s t i n g . L i n e a r , p l a n a r , l i n e a r h y p e r - s u r f a c e , and q u a d r a t i c c u r v e d l i n e s and s u r f a c e s a r e f i t t e d t o the r e l e v a n t p a r a m e t e r s i n o r d e r to a s s e s s the l e v e l of a c c e p t a n c e of the p r o p o s e d h y p o t h e s i s . S t a t i s t i c a l a s s e s s m e n t i n terms of m u l t i p l e and p a r t i a l c o r r e l a t i o n c o e f f i c i e n t s , l e v e l s of s i g n i f i c a n c e , and c o n f i d e n c e l i m i t s a r e d e t e r m i n e d f o r the b e s t f i t s u r f a c e . I t i s c o n c l u d e d a t t h i s s t a g e t h a t s t r e s s i s not s i g n i f i c a n t i n terms of d i l u t i o n s i n c e n u m e r i c a l m o d e l l i n g i n d i c a t e d t h a t the 7 h a n g i n g and f o o t w a l l of i n d i v i d u a l s t o p e s at R u t t a n a r e i n a s t a t e of r e l a x a t i o n , t h u s r e s u l t i n g i n s t r u c t u r a l l y c o n t r o l l e d f a i l u r e s . T h i s s t a t e m e n t w i l l be f u r t h e r r e i n f o r c e d t h r o u g h measurement and o b s e r v a t i o n a l a p p r o a c h e s . H) A p p l i c a t i o n : T h i s c h a p t e r a n a l y z e s the r e l a t i o n s h i p s d e r i v e d from the e x i s t i n g d a t a base to s t o p e s s u b s e q u e n t l y mined. A b r i e f c o m p a r a t i v e a n a l y s i s i s made between the most p r o s p e c t i v e e x i s t i n g methods of s t o p e d e s i g n and the e m p i r i c a l method p r o p o s e d i n t h i s t h e s i s . I) C o n c l u s i o n s : The a c c e p t a n c e or r e j e c t i o n of the f o l l o w i n g h y p o t h e s i s i s made: Optimum Stope Geometry = f ( R o c k Q u a l i t y , E x t r a c t i o n R a t e , Exposed S u r f a c e A r e a ) 8 CHAPTER TWO THE RUTTAN MINE 2.1 I n t r o d u c t i o n I n o r d e r t o u n d e r s t a n d t h e p a r a m e t e r s i n v o l v e d i n d e v e l o p i n g a m e t h o d o f s t o p e d e s i g n f o r t h e R u t t a n o r e b o d y , i t i s i m p o r t a n t t o know t h e h i s t o r y , g e o l o g y , m i n i n g p r a c t i c e a n d t h e m i n e g e o m e t r y . S t u d y i n g t h e i n f l u e n c i n g f a c t o r s r e q u i r e s t h a t t h e m e t h o d o l o g y be i n t e g r a t e d i n t o t h e o v e r a l l m i n e r e g i m e . T h i s i n v o l v e s , i n a d d i t i o n t o n u m e r i c a l a n d a n a l y t i c a l a n a l y s e s , a c o o r d i n a t e d f i e l d e f f o r t d r a w i n g f r o m a l l t h e a v a i l a b l e i n f o r m a t i o n a n d r e - a n a l y z i n g t h a t i n f o r m a t i o n f r o m a d i f f e r e n t p e r s p e c t i v e . T h i s c h a p t e r d e s c r i b e s t h e f i r s t s t a g e o f d e v e l o p i n g a d a t a b a s e w h i c h w i l l o u t l i n e t h e a s s o c i a t e d g e o m e t r i c c o m p l e x i t i e s a s s o c i a t e d w i t h t h e R u t t a n o r e b o d y . T h e R u t t a n m i n e i s l o c a t e d i n n o r t h e r n M a n i t o b a , 760km n o r t h o f W i n n i p e g a n d 20km e a s t o f t h e town o f L e a f R a p i d s , F i g u r e 1.1. T h e R u t t a n c o p p e r - z i n c o r e b o d y i s a m u l t i - l e n s e d , s t e e p l y d i p p i n g ( 7 0 ° ) e n e c h e l o n d e p o s i t . I n d i v i d u a l l e n s e s h a v e a maximum s t r i k e l e n g t h o f 350m a n d w i d t h s v a r y i n g f r o m 7 t o 61m. The m i n i n g m e t h o d p r a c t i c e d i s b l a s t h o l e o p e n s t o p i n g w i t h d e l a y e d f i l l . P r o d u c t i o n , F i g u r e 1.2, commenced by o p e n p i t i n A p r i l o f 1973 a n d c o n t i n u e d u n t i l Dec, 1 9 8 0 . The p i t a t t h i s t i m e was 1000m l o n g , 600m w i d e a n d 200m d e e p . T h e R u t t a n 9 o r e b o d y i s c o n s i d e r e d to be open a t the 860m l e v e l ( b e l o w s u r f a c e ) . The u n d e r g r o u n d o p e r a t i o n was d e v e l o p e d to 430m b e l o w s u r f a c e and i s commonly r e f e r r e d to as the " U p p e r M i n e " . P r o d u c t i o n f rom the U p p e r Mine commenced i n M a r c h , 1979 and i s p r e s e n t l y a t 6 0 0 0 t p d . The r e m o v a l of the e n t i r e s u r f a c e c rown p i l l a r i n the summer of 1988 w i l l c o m p l e t e the m i n i n g of the Upper M i n e . D e l i n e a t e d r e s e r v e s e x i s t to the 860m l e v e l y i e l d i n g t o n n a g e s s u f f i c i e n t f o r m i n i n g u n t i l 1992 a t a p r o d u c t i o n r a t e o f 8 0 0 0 t p d . The " L o w e r M i n e " i s d e f i n e d as t h a t p o r t i o n of the o p e r a t i o n t h a t e x i s t s b e t w e e n the 430m l e v e l and the 860m l e v e l . In O c t o b e r of 1985 m i n i n g o f the Lower Mine commenced w h i l e the U p p e r Mine was p h a s i n g down. A s i g n i f i c a n t l y l a r g e d a t a base o f i n f o r m a t i o n i s a v a i l a b l e f rom t h e U p p e r M i n e , c o n t a i n i n g a p p r o x i m a t e l y 56 s t o p e s of w h i c h 48 have been m i n e d a t the t i m e of the c o m p l e t i o n o f t h i s s t u d y . I t was d e c i d e d to t e r m i n a t e the d a t a g a t h e r i n g s t a g e i n F e b r u a r y 1985 w i t h the s u b s e q u e n t l y m i n e d s t o p e s (8 ) s e r v i n g to r e i n f o r c e or d i s p r o v e the p r o p o s e d f o r m u l a t e d h y p o t h e s i s . 2.2 G e o l o g y o f t h e R u t t a n D e p o s i t The R u t t a n O r e b o d y i s a c o p p e r - z i n c r i c h , e x h a l a t i v e , m a s s i v e s u l p h i d e d e p o s i t c o n t a i n e d w i t h i n a s e q u e n c e of P r o t e r o z o i c v o l c a n i c r o c k s and t h e i r d e r i v e d s e d i m e n t s . R u t t a n i s l o c a t e d w i t h i n the C h u r c h i l l G e o l o g i c P r o v i n c e of M a n i t o b a , 10 F i g u r e 2.3. T h i s g e o l o g i c p r o v i n c e i s c h a r a c t e r i z e d by two e a s t - w e s t t r e n d i n g v o l c a n i c a r c b e l t s , the Wasekwan Group to the n o r t h and the Amisk Group to the s o u t h , s e p a r a t e d by a wide s e d i m e n t a r y b a s i n termed the Burntwood R i v e r S u i t e , F i g u r e 2.3. T h i s i s p a r t i c u l a r l y i m p o r t a n t i n r e l a t i n g the o r o g e n y of the d e p o s i t to i t s p r e s e n t c o n f i g u r a t i o n and s t r e s s r e g i m e . The R u t t a n d e p o s i t i s Ap h e b i a n i n age and i s i n t e r p r e t e d to be a s y n c l i n a l d e p o s i t a s s o c i a t e d w i t h i s l a n d a r c d e v e l o p m e n t . T h i s i s g r a p h i c a l l y shown i n the s u b s e q u e n t s e c t i o n c o n c e r n i n g the t e c t o n i c h i s t o r y of R u t t a n . The Wasekwan Group c o n s i s t s of a c o n f o r m a b l e sequence of v o l c a n i c f l o w s , t u f f s , a g g l o m e r a t e s , b r e c c i a s and v o l c a n i c l a s t i c s e d i m e n t s . O v e r l y i n g t h i s package of r o c k s a r e the s h a l l o w water s e d i m e n t s of the S i c k l e g r o u p . A r c h e a n basement b o r d e r s the Wasekwan and S i c k l e Groups to the n o r t h . The v o l c a n i c r o c k s of the Wasekwan and S i c k l e Groups have been c o n s i d e r a b l y a l t e r e d d u r i n g r e g i o n a l metamorphism to l o w e r a m p h i b o l i t e , a m p h i b o l i t e and g r e e n s c h i s t f a c i e s . B a s i c v o l c a n i c r o c k s and s e d i m e n t s have been c o n v e r t e d to s c h i s t s and banded g n e i s s e s l o c a l l y c h a r a c t e r i z e d by e p i d o t e , h o r n b l e n d e , b i o t i t e , c h l o r i t e , g a r n e t , s t a u r o l i t e , c o r d i e r i t e and a n d a l u s i t e a l t e r a t i o n . 1 1 2.2 .1. Local Geology The R u t t a n mine i s t h o u g h t to be a g e o s y n c l i n a l d e p o s i t a s s o c i a t e d w i t h i s l a n d a r c d e v e l o p m e n t . T h i s i s where a p l a t e of l i t h o s p h e r e i s s l o w l y p l u n g i n g downwards i n t o the m a n t l e . The v o l c a n i s m t h a t b u i l d s the v o l c a n i c m o u n t a i n s i s p r e s u m a b l y c a u s e d by the m e l t i n g of the downgoing p l a t e , F i g u r e 2.4. T h e r e f o r e , the R u t t a n d e p o s i t i s assumed to have been formed a l o n g a f l a n k of a l a r g e v o l c a n o . T h i s v o l c a n i c a r c t r e n d s e a s t - w e s t as shown i n F i g u r e 2.3. A s c h e m a t i c s e c t i o n , drawn p e r p e n d i c u l a r to the t r e n d of the i s l a n d a r c , i s employed to d e s c r i b e the sequence of e v e n t s l e a d i n g to the f o r m a t i o n of the R u t t a n d e p o s i t , F i g u r e 2.5. I t i s b e s t summarized as f o l l o w s : - R u t t a n was formed b e n e a t h sea l e v e l as a r e s u l t of magma b e i n g v e n t e d w i t h i n a g r a n i t i c h o s t . - B a s a l t f l o w s were d e p o s i t e d then s u b s e q u e n t l y o v e r l a i n by a sequence of v o l c a n i c a l l y d e r i v e d s e d i m e n t s . P i l l o w s t r u c t u r e s a r e f o u n d w i t h i n the b a s a l t u n i t i n d i c a t i n g t h a t t h i s u n i t was emplaced a t a r o c k - w a t e r i n t e r f a c e . The f o o t w a l l v o l c a n i c l a s t i c s a r e as a r e s u l t of a c i d v o l c a n i s m and i t s s u b s e q u e n t e r o s i o n . The r o c k i s q u i t e u n i f o r m , t h i n l y to t h i c k l y bedded, r e l a t i v e l y u n a l t e r e d and composed of f i n e g r a i n e d , i n t e r m e d i a t e , c l a s t i c f r a g m e n t s . T h i s u n i t g r a d e s i n t o the f o o t w a l l a l t e r e d v o l c a n i c l a s t i c s w hich i s c h a r a c t e r i z e d by i n c r e a s e d a l t e r a t i o n and the p r e s e n c e of c o r d i e r i t e , s t a u r o l i t e 12 and m a g n e t i t e . - The mine r h y o l i t e s ( q u a r t z i t e s ) f o l l o w i n s e q u e n c e . They a r e the p r o d u c t s of e r o s i o n from the f l a n k s of the v o l c a n o . These r h y o l i t e s were i n t e r b e d d e d w i t h c h a n n e l w a y s of mud d e p o s i t s . T h i s i s a f e l s i c r o c k which was s u b s e q u e n t l y r e p l a c e d by c o p p e r and z i n c r i c h s o l u t i o n s o r i g i n a t i n g from the m i n e r a l i z e d v e n t . The mud zones were h y d r o t h e r m a l l y a l t e r e d to c h l o r i t e and c h l o r i t e - t a l c s c h i s t on b o t h the f o o t w a l l and h a n g i n g w a l l c o n t a c t s of the ore l e n s e s . - O v e r l y i n g the mine r h y o l i t e i s the e x h a l i t e h o r i z o n which was formed as a p r e c i p i t a t e r e s u l t i n g from the m i x i n g of the h y d r o t h e r m a l f l u i d s and s e a w a t e r on the sea f l o o r . The z i n c r i c h l e n s e s of the R u t t a n d e p o s i t a r e f o u n d i n the E x h a l i t e u n i t and a r e c h a r a c t e r i z e d by p y r i t e - s p h a l e r i t e - s i 1 i c a t e and c h e r t b a n d i n g . W e l l bedded d e t r i t a l s e d i m e n t s dominate the upper p o r t i o n s of t h i s h o r i z o n . The s u l p h i d e l e n s e s formed a r e s e d i m e n t a r y i n f o r m a t i o n u n l i k e the i g n e o u s o r i g i n of the l e n s e s w i t h i n the mine r h y o l i t e s . ^ - F i n a l l y , low ( s e d i m e n t s ) and h i g h e n e r g y ( t u r b i d i t e s ) v o l c a n i c a l l y d e r i v e d d e p o s i t s s e t t l e d o v e r the e x h a l a t i v e h o r i z o n . I t (PM u n i t ) c o n s i s t s of i n t e r b e d d e d g r a y w a c k e s and v o l c a n i c ( e r o s i o n ) d e r i v e d c o n g l o m e r a t e s . Subsequent d e f o r m a t i o n was i n the form of s h e a r i n g of the weaker s u l p h i d e d e p o s i t s and the f u r t h e r i n t r u s i o n of a system of dykes t h r o u g h o u t the above hor i z on s . The above sequence of e v e n t s a r e s e d i m e n t a r y i n n a t u r e 13 r e s u l t i n g i n f l a t l y d i p p i n g d e p o s i t s . I t i s p o s t u l a t e d t h a t , a f t e r the d e p o s i t i o n of the R u t t a n d e p o s i t , the C h u r c h i l l p r o v i n c e had s u b d u c t e d u n d e r n e a t h the S u p e r i o r p r o v i n c e . T h i s t e c t o n i c a c t i v i t y r e s u l t e d i n the i n c l i n a t i o n of the ore body to t h a t shown i n F i g u r e 2.6. The combined t e c t o n i c a c t i v i t y of the i n i t i a l i s l a n d a r c d e v e l o p m e n t and the s u b s e q u e n t s u b d u c t i o n r e s u l t e d i n a l a t e phase of r e g i o n a l metamorphism to i n f l u e n c e the R u t t a n d e p o s i t . T h i s l a t e phase of metamorphism c o n v e r t e d the b a s i c v o l c a n i c r o c k s to h o r n b l e n d e , p l a g i o c l a s e s c h i s t s and banded g n e i s e s w i t h v a r i a b l e amounts of e p i d o t e , b i o t i t e and c h l o r i t e . The s e d i m e n t s were c o n v e r t e d to b i o t i t e , m u s c o v i t e , q u a r t z s c h i s t s and g n e i s s e s . An a l t e r a t i o n zone i s a s s o c i a t e d w i t h the R u t t a n d e p o s i t w h i c h i s d o m i n a t e d by a b i f u r c a t i n g s h e a r zone. The s h e a r zone a t R u t t a n i s o r i e n t e d a t N7 0* E d i p p i n g at 68° SE. I t i s up to 30m wide and b i f u r i c a t e s i n t o t h r e e main s h e a r z o n e s : A r t ' s F a u l t , N o r t h W a l l Shear and E a s t S h e a r , F i g u r e 2.7. The o v e r a l l e f f e c t of the s h e a r i n g was to s i g n i f i c a n t l y change the geometry of the ore l e n s e s and a l t e r a t i o n z o n e s . The i n d i v i d u a l mine r o c k u n i t s w i l l be f u r t h e r d e s c r i b e d i n the c o n t e x t of " r o c k masss c h a r a c t e r i z a t i o n " , C h a p t e r 5. F i g u r e 2.8 i s a g e o l o g i c p l a n of the R u t t a n a r e a . 2.3 Orebody Geometry The R u t t a n o r e b o d y c o m p r i s e s n i n e ore l e n s e s a l l 14 s u b p a r a l l e l i n a t t i t u d e and e c h e l o n i n n a t u r e , F i g u r e 2.7. The orebody s t r i k e s N7 0°E, d i p s 7 0°SE and p l u n g e s 70°to the e a s t . The maximum d i m e n s i o n s of the ore zone a r e 120 metres wide by 700 m e t r e s l o n g . An open p i t l i e s i m m e d i a t e l y above the u n d e r g r o u n d w o r k i n g s to a d e p t h of 210 m e t r e s . The g e o m e t r y of the l e n s e s i s s u c h t h a t to the west of the e a s t s h e a r , f i v e major l e n s e s form a zone w i t h a s t r i k e l e n g t h of 350m a t the 260m l e v e l ( below s u r f a c e ) which n a r r o w s to 200m a t the 430m l e v e l . These a r e known as the "west l e n s e s " and the w i d t h of the i n d i v i d u a l l e n s e s range from 7 to 35m. The west l e n s e s bottom out a t the 660m l e v e l whereas the " e a s t l e n s e s " c o n t i n u e to a y e t unknown d e p t h . These l e n s e s l i e e a s t of the e a s t s h e a r and a r e c o m p r i s e d of f o u r l e n s e s . G e n e r a l l y , the ore c o n t a c t s a r e i r r e g u l a r b o t h i n p l a n and s e c t i o n and p i n c h and s w e l l down d i p , t h e r e b y e n c l o s i n g narrow bands of w a s t e , F i g u r e 2.9,2.10. C o n s e q u e n t l y , i n o r d e r to p r o p e r l y d e l i n e a t e the s t o p e geometry , diamond d r i l l i n g i s ' c o n d u c t e d on a 15m by 15m p a t t e r n a l o n g the ore c o n t a c t , F i g u r e 2.11. The c o m p l e x i t y of the ore geometry i s i n d i c a t e d by F i g u r e 2.J.2. I n d i v i d u a l s t o p e s a r e d e f i n e d by draw l e v e l , a l e t t e r d e s i g n a t i n g the l e n s and a number d e f i n i n g the s t o p e w i t h i n t h a t l e n s . An example i s 320-11B. T h i s s t o p e Is drawn o f f the 320m l e v e l , i s a "B" l e n s as d e f i n e d i n F i g u r e 2.9 and i s s t o p e number "11" w i t h i n t h a t l e n s . G e n e r a l l y , a s t o p e h a v i n g a s i m i l a r number i s l o c a t e d e i t h e r i n the f o o t w a l l or h a n g i n g w a l l of the p r e c e d i n g s t o p e . The "B" l e n s e s a r e l o c a t e d i n the 15 f o o t w a l l of the "C" which a r e l o c a t e d i n the f o o t w a l l of the "D" l e n s e s . T h i s t e r m i n o l o g y w i l l be u s e f u l i n i d e n t i f y i n g a r e a s of the mine. Stope numbers i n c r e a s e from w e s t ( 7 to 16) to eas t ( 1 7 to 22 ) . 2.4 Mining P r a c t i c e The R u t t a n o r e b o d y i s a complex a r r a n g e m e n t of ore l e n s e s . These l e n s e s a r e l o c a t e d i n c l o s e p r o x i m i t y to each o t h e r and j o i n i n c e r t a i n l o c a t i o n s . Such c o m p l e x i t y and i r r e g u l a r i t y of ore o u t l i n e s r e q u i r e t h a t m i n i n g of the i n d i v i d u a l l e n s e s be c a r r i e d out i n a p r e d e t e r m i n e d sequence i n o r d e r to e n s u r e maximum ground s t a b i l i t y . The s t o p i n g method i s b l a s t h o l e open s t o p i n g w i t h d e l a y e d f i l l . Two v a r i a t i o n s of open s t o p i n g a r e u s e d . In one, c o n v e n t i o n a l s m a l l d i a m e t e r (51mm) h o l e s a r e d r i l l e d from l e v e l s s p a c e d a t 30m v e r t i c a l i n t e r v a l s . In the s e c o n d , l a r g e d i a m e t e r (165mm) h o l e s are d r i l l e d from l e v e l s s p a c e d at 60m v e r t i c a l i n t e r v a l s . The b l a s t i n g sequence i n t h e s e " l a r g e d i a m e t e r s t o p e s " i s 'a c o m b i n a t i o n of v e r t i c a l c r a t e r r e t r e a t and s l a s h . S t o p e s and p i l l a r s a r e l a i d out on a r e g u l a r p a t t e r n and res e m b l e the d i m e n s i o n s o u t l i n e d i n F i g u r e 2.13. In g e n e r a l , s t o p e s and p i l l a r s a r e a p p r o x i m a t e l y 30m and 15m i n l e n g t h r e s p e c t i v e l y . P i l l a r r e c o v e r y Is an i n t e g r a l p a r t of the normal s t o p i n g p r o g r e s s i o n . When a s t o p e i s mined o u t , i t i s p l a n n e d to be b a c k f i l l e d u s i n g c l a s s i f i e d m i l l t a i l s . The a d j a c e n t 16 s t o p e i s mined back to the p r e d e t e r m i n e d p i l l a r l i n e , then the r e m a i n i n g p i l l a r i s b l a s t e d i n t o the open s t o p e l e a v i n g a 6m remnant of ore to r e t a i n the f i l l . In p r a c t i c e , t h i s i s g e n e r a l l y n ot the c a s e s i n c e the f i l l i n g c y c l e i s w e l l b e h i n d s c h e d u l e , t h e r e b y n o t e n a b l i n g the f i l l i n g of s t o p e s p r i o r to the m i n i n g of the a d j a c e n t s t o p e . C o n s e q u e n t l y , the r i b p i l l a r i s b l a s t e d to the 6m remnant w i t h o u t the b e n e f i t of f i l l . A f t e r r e m o v a l of the b r o k e n p i l l a r o r e , the s t o p e and p i l l a r v o i d i s then b a c k f i l l e d w i t h m i l l t a i l s . The f i l l forms the draw l e v e l f o r the n e x t m i n i n g l i f t . D r a w p o i n t l e v e l s a r e e s t a b l i s h e d a t 60m v e r t i c a l i n t e r v a l s . A c t i v e draw l e v e l s a r e c u r r e n t l y the 260m, 320m, 370m and 430m l e v e l s . Due to the i r r e g u l a r i t y of the ore l e n s e s , i t i s sometimes n e c e s s a r y to l o c a t e a d d i t i o n a l d r a w p o i n t s on l e v e l s o t h e r t h a n the main l e v e l s . T h i s c o n s e q u e n t l y r e s u l t s i n s t o p e h e i g h t s b e i n g l e s s than 60m. I n t e r m e d i a t e d r i l l l e v e l s a r e d r i v e n between the main l e v e l s c r e a t i n g a 30m l e v e l i n t e r v a l i n s t o p i n g a r e a s whe"re s m a l l d i a m e t e r b l a s t h o l e s a r e u t i l i z e d . A l l p r o d u c t i o n b l a s t i n g i s w i t h ANFO and pa c k a g e d water g e l s . N o n - e l e c t r i c d e l a y s a r e used to e f f e c t p r o p e r s e q u e n c i n g of i n i t i a t i o n . 2.4.1 Stoping Method G e n e r a l l y , t r a n s v e r s e l e a v i n g a remnant p i l l a r as open s t o p i n g i s shown i n F i g u r e employed a t R u t t a n 2.13. Mine p r a c t i c e 17 d i c t a t e s t h a t where the ore w i d t h e x c e e d s 30m, a l o n g i t u d i n a l p i l l a r i s l e f t , t h e r e b y e n s u r i n g t h a t the s t o p e w i d t h does not e x c e e d 30m. These v a l u e s have been d e t e r m i n e d e m p i r i c a l l y t h r o u g h t r i a l and e r r o r . As p r e v i o u s l y i n d i c a t e d , the R u t t a n o p e r a t i o n employs two v a r i a t i o n s of open s t o p i n g . F i g u r e 2.14 d e p i c t s the c o n v e n t i o n a l method of open s t o p i n g e m p l o y i n g 51mm d i a m e t e r h o l e s . I n i t i a l l y , the u n d e r c u t i s s i l l e d out f o r a v e r t i c a l h e i g h t of 12m from f o o t w a l l to h a n g i n g w a l l and remnant to r e m n a n t . p i l l a r . The 2m x 2m s l o t i s mined e i t h e r c o n v e n t i o n a l l y or r a i s e b o r e d to a 12m h e i g h t above the u p p e r d r i l l l e v e l . In a d d i t i o n to s l o t d e v e l o p m e n t , i t i s r e q u i r e d to d e v e l o p a f o o t w a l l and h a n g i n g w a l l d r i v e w h i c h a r e n o r m a l l y l o c a t e d a t the ore c o n t a c t . I t i s the p r a c t i c e a t R u t t a n t h a t a s i n g l e d r i l l d r i v e be d r i v e n t h r o u g h the c e n t r e of the s t o p e i f the ore w i d t h does not e x c e e d 15m. S i m i l a r d e v e l o p m e n t o c c u r s on the i n t e r m e d i a t e l e v e l . The 2m x 2m s l o t r a i s e i s s u b s e q u e n t l y s l a s h e d to 3.7m x 3.7m f o r the f u l l s t o p e h e i g h t . S u b s e q u e n t 1 y the s l o t i s s l a s h e d f u l l w i d t h from h a n g i n g w a l l ' t o f o o t w a l l . R i n g s a r e t h e n s l a s h e d i n t o the v o i d f o r the f u l l s t o p e w i d t h on e i t h e r s i d e of the s l o t , a s s u m i n g a c c e s s e x i s t s on e i t h e r s i d e . N o r m a l l y , the r i n g s t h a t are b l a s t e d from the i n t e r m e d i a t e l e v e l c o r r e s p o n d to a s i m i l a r s e t of r i n g s on the upper d r i l l l e v e l , t h e r e b y e n s u r i n g t h a t a c o n t i n u o u s v o i d e x t e n d s from the draw l e v e l to 12.2m above the upper d r i l l d r i v e . The s t o p e i s g e n e r a l l y d r i l l e d o f f p r i o r to the commencement of s l o t b l a s t i n g . The u p h o l e s on the i n t e r m e d i a t e and draw l e v e l a r e r e q u i r e d to e n s u r e t h a t p r o p e r " i n t e r - l e a f " c o v e r a g e between d r i l l h o l e s o c c u r s between l e v e l s . N o r m a l l y , the r i n g s are s p a c e d a t a s p a c i n g of 1.5m and a toe burden of 2.1m, and o n l y a s u f f i c i e n t number of h o l e s a r e d r i l l e d f o r t h a t p a r t i c u l a r b l a s t . The second method, F i g u r e 2.14, i n v o l v e s a m o d i f i e d form of " v e r t i c a l ? , c r a t e r r e t r e a t " and s l a s h . L a r g e 151mm d i a m e t e r h o l e s a r e employed, t h e r e b y a l l o w i n g l o n g e r h o l e s to be d r i l l e d by u s i n g i n the h o l e hammer type of d r i l l e q u i p m e n t . T h i s e n a b l e s the d e l e t i o n of i n t e r m e d i a t e l e v e l s . S i m i l a r l y , an u n d e r c u t i s t a k e n as w i t h the c o n v e n t i o n a l method. The " v c r s l o t " i s drop r a i s e d from the upper d r i l l l e v e l to a 3.7 x 3.7m r a i s e . The s l o t i s n o t n e c e s s a r i l y t a k e n t h r o u g h to the upper l e v e l p r i o r to p r o d u c t i o n b l a s t i n g . The p r o d u c t i o n b l a s t i n g r e q u i r e s the w i d e n i n g of the s l o t to 6.1 x6.lm and s u b s e q u e n t l y s l a s h i n g f u l l s t o p e w i d t h from h a n g i n g w a l l to f o o t w a l l . The main tonnage Is a c h i e v e d t h r o u g h s l a s h i n g d e c k e d c h a r g e s i n t o the v o i d . The d e c k e d r i n g s a r e b l a s t e d f u l l s t o p e w i d t h as i n the c o n v e n t i o n a l method d e s c r i b e d p r e v i o u s l y . The r i n g s are spaced 3m a p a r t w i t h a toe burden of 4.2m. The s l o t , t h e r e f o r e , i s the o n l y p a r t of the s t o p e t h a t i s a d v a n c e d e m p l o y i n g the " v e r t i c a l c r a t e r r e t r e a t " method of m i n i n g , which i s c h a r a c t e r i z e d by s p h e r i c a l c h a r g e s (6:1=L/D). D e v i a t i o n s of the above methods l i e i n the f o l l o w i n g : - The i n i t i a l s l o t i s b o r e d by machine from the' draw -l e v e l to the upper d r i l l l e v e l . - The V C R - S l a s h method may have the s l o t e n t i r e l y c o m p l e t e p r i o r to commencement of s l a s h i n g . S u b s e q u e n t l y , l o n g p a r a l l e l r i n g s w i l l be b l a s t e d f o r the f u l l h e i g h t of the s t o p e . The s t o p e i s u l t i m a t e l y f i l l e d to 12.2m above the upper d r i l l l e v e l . Upon f i l l c o n s o l i d a t i o n , the p r e v i o u s upper d r i l l d r i v e w i l l f_(>rm the draw l e v e l f o r the n e x t l i f t . The draw cones a r e formed out of the f i l l . The sequence of e x t r a c t i o n f o r an i n d i v i d u a l s t o p e i s as summarized by F i g u r e s 2.15,2.16. The e x t r a c t i o n s e q u e n c e f o r an i n d i v i d u a l l e n s i s g e n e r a l l l y from the h a n g i n g w a l l l e n s to the f o o t w a l l and from the c e n t e r of an i n d i v i d u a l l e n s to the e x t r e m i t i e s . T h i s a g a i n i s not g e n e r a l l y f o l l o w e d s i n c e p r o d u c t i o n r e q u i r e m e n t s n e c e s s i t a t e d c h a n g es t o i n d i v i d u a l m i n i n g a r e a s . The s i g n i f i c a n c e of m i n i n g sequence w i l l be a n a l y z e d i n C h a p t e r 4 ( S t r e s s ) 2.5 O b s e r v a t i o n s / C o n c l u s i o n s T h i s s e c t i o n was i n c l u d e d to document the d i f f i c u l t i e s t h a t w i l l p r e s e n t t h e m s e l v e s i n t r y i n g to c a t e g o r i z e the i n d i v i d u a l s t o p e s i n t o a d a t a b a s e , or to even commence a n a l y z i n g by a s u i t a b l e n u m e r i c a l c o d e . The f o l l o w i n g c a t e g o r i e s of s t o p e s g e n e r a l l y o c c u r a t R u t t a n , F i g u r e 2.17: 20 - i s o l a t e d - r i b : s t o p e s e x i s t a l o n g s t r i k e - e c h e l o n : s t o p e s e x i s t a l o n g d i p The v a r i a n c e i n m i n i n g s e q u e n c e , F i g u r e s 2.15,2.16 i s not s y s t e m a t i c or m e t h o d i c a l but i s p r i m a r i l y a f u n c t i o n of p r o d u c t i o n r e q u i r e m e n t s . T h i s i s the c a s e i n most m i n i n g o p e r a t i o n s J j i Canada. The c o n t r o l l e d e x p e r i m e n t t h a t one would l i k e to a c h i e v e f o r a t h e s i s now i s s t a r t i n g to a c c u m u l a t e many v a r i a b l e s . An e x p e r i m e n t a l s t o p e would y i e l d q u a n t i t a t i v e and q u a l i t a t i v e o b s e r v a t i o n s . The d i f f i c u l t y a r i s e s i n e x t r a p o l a t i n g the r e s u l t s to o t h e r a r e a s of the mine e x h i b i t i n g d i f f e r e n t r o c k q u a l i t i e s , s t o p e c o n f i g u r a t i o n s and m i n i n g p r a c t i c e s . The d a t a base would have to be e n l a r g e d , which would mean an " e x p e r i m e n t a l mine" r a t h e r than an i n d i v i d u a l s t o p e would have to be i n s t r u m e n t e d . At the time of the s t u d y , the Upper Mine was i n an a d v a n c e d s t a g e of e x t r a c t i o n and had r e s e r v e s f o r o n l y t h r e e more y e a r s . A t e s t s t o p e , t h a t would be i s o l a t e d from a d j a c e n t w o r k i n g s , was not a v a i l a b l e . A f u r t h e r r e s t r i c t i o n was t h a t i t t a k e s a p p r o x i m a t e l y t e n (10) months f o r a s t o p e to be c o m p l e t e l y e x c a v a t e d and a n o t h e r seven months to f i l l . The a p p r o a c h t a k e n was to a n a l y z e the e x i s t i n g d a t a base and to d e r i v e , i f p o s s i b l e , c r i t i c a l p a r a m e t e r s and a r e a s to be f u r t h e r s t u d i e d . A r o c k m e c h a n i c s program at R u t t a n had been implemented from i n c e p t i o n which b a s i c a l l y i n c l u d e d s t r e s s gauges and e x t e n s o m e t e r s . S t o p e s , as they have been e x t r a c t e d , were e v a l u a t e d i n t h e s e terms w i t h minor s u c c e s s . A program has 21 now been Implemented a t R u t t a n where an I s o l a t e d s t o p e Is b e i n g m o n i t o r e d i n the Lower Mine to p r o v e or d i s p r o v e the t h e o r i e s and i d e a s b r o u g h t f o r t h i n t h i s t h e s i s . The s t o p e w i l l be mined from O c t o b e r 1985 to O c t o b e r 1986 and the r e s u l t s w i l l be a n a l y s e d . T h i s t h e s i s i s the f i r s t phase of the d e v e l o p m e n t of a m e t h o d i c a l a p p r o a c h to a s s e s s i n g the p a r a m e t e r s t h a t a r e of p a r t i c u l a r s i g n i f i c a n c e to s t o p e d e s i g n a t R u t t a n . F i g u r e 2.1: L o c a t i o n Map 23 F i g u r e 2.2: L o n g i t u d i n a l o f R u t t a n Mine (Speakman e t a l , 1976) > ^ \ - D , A B A s e DYKES (Mackenzie Swarm) . ISLAND A R C AMISK (A) WASEKWAN (W ) Figure 2.3: R e g i o n a l Geology Mantle F i g u r e 2.4: I s l a n d Arc Development SEA LEVEL F i g u r e 2.5: S c h e m a t i c S e c t i o n Showing t h e F o r m a t i o n o f the R u t t a n D e p o s i t (Speakroan e t a l , 1976) 25 CHURCHILL SUPERIOR OCEAN FLOOR RUTTAN ORE LENSES UTHOSPHER6>. ^ M0VE5V Figure 2.6: T e c t o n i c E v o l u t i o n l g u c e 2.7: I.«.t.le Diagram - Deposit F i g 26 BASALT UNIT £3 FOOTWALL VOLCAMCLASTICS |JTn ALTERED FOOTWALL ™ VOLCAMCLASTICS ^3 M l « RHYOLITE H MASSIVE SULPHIOES PI EXHALITE P M UNIT OORITE QUARTZ DIORITE GAB8HO j FELSIC INTRUSIVE £3 DIABASE DYKE R U T T A N A R E A GEOLOGY PLAN F i g u r e 2 . 8 : L o c a l G e o l o g y F i g u r e 2.9: P l a n of Ore L e n s e s - 260m L e v e l - Numbers R e f e r t o Sequence o f E x t r a c t i o n T y p i c a l Stope Dimensions Stope Height (H) = 40-100 m Stope Length (L) = 40-50 m Stope Width (W) = 6-30 m Rib P i l l a r Length <= 6 m F i g u r e 2.13: T y p i c a l Stope D i m e n s i 2 9 TOP OF S T O P E *jT 1st LIFT 15m ^— DRILL L E V E L 31 m INTERMEDIATE L E V E L 31 m a) SUB-LEVEL (51mm) I2m UNDERCUT DRAW L E V E L _ _ TOP OF S T O P E t 1st L I F T 15 m D R I L L L E V E L 4 6 m 12m U N D E R C U T D R A W L E V E L b) VCR-SLASH (165mm) F i g u r e 2.14: Stoping Method 30 2 n d L I F T 1) I n i t i a l Development - D r i l l Drives - S l o t X-Cut - Sl o t Raise 2) Stope S i l l e d Out Alternative 3) Slo t Taken F u l l Stope Width (HW to FW). Rings Blasted on E i t h e r Side of Slo t and Retreat to P i l l a r Access 3a) Blasted Rings on Upper Levels Not Duplicated Below. 3b) Blasted Rings Coinciding on Each Level F i g u r e 2.15: Sequence o f E x t r a c t i o n - C o n v e n t i o n a l 1) I n i t i a l Development 2) Stope S i l l e d Out - D r i l l Drives - Slot X-Cut - Sl o t Raise A l t e r n a t i v e 3) S l o t Blasted and Stope Benched for F u l l Stope Width 3a) Slo t Taken Through to Upper Level and Slashed f o r the F u l l Stope Width. Production Slashing on Either Side of S l o t . F i g u r e 2.16: Sequence of E x t r a c t i o n - VCR + S l a s h ISOLATED ADJACENT RIB ECHELON t « > *•. - > . / F i g u r e 2.17: C a t e g o r i z a t i o n of Stopes - Plan View The term " e c h e l o n " i s synonomous w i t h " p a r a l l e l " f o r t h e c o n t e x t t h a t I t i s employed i n t h i s t h e s i s 33 CHAPTER THREE STOPE DESIGN METHODOLOGY 3.1 I n t r o d u c t i o n A t h e s i s i s d e f i n e d by the " O x f o r d E n g l i s h D i c t i o n a r y " as "a t h e o r y put f o r w a r d and s u p p o r t e d by a r g u m e n t s " . T h i s c h a p t e r w i l l i d e n t i f y the p r o b l e m , s e t t i n g f o r t h the o b j e c t i v e s , d e l i n e a t i n g the i n p u t r e q u i r e m e n t s and f o r m u l a t i n g whether to a c c e p t or r e j e c t the g o v e r n i n g h y p o t h e s i s . The f i r s t p a r t of the c h a p t e r w i l l summarize a l i t e r a t u r e s e a r c h of methods i n s t o p e d e s i g n and "Rock Mass C l a s s i f i c a t i o n " s y s t ems c u r r e n t l y a v a i l a b l e . A s e c t i o n i s i n c l u d e d on the d e s i g n methods employed a t R u t t a n p r i o r to t h i s s t u d y and a d i s c u s s i o n on why the p r e v i o u s t h e o r y was n o t a p p l i c a b l e . The f i n a l p a r t of the c h a p t e r w i l l r e v i e w a q u e s t i o n n a i r e t h a t examines the s t a t e of r o c k m e c h a n i c s d e s i g n and, i n p a r t i c u l a r , o p e n i n g d e s i g n i n Canada t o d a y . T h i s q u e s t i o n n a i r e was i n c l u d e d to show t h a t the pr o b l e m of s t o p e d e s i g n i s u n i v e r s a l and not a " R u t t a n " p r o b l e m . 3.2 L i t e r a t u r e Review T h e r e e x i s t s no a c c e p t e d c o m p r e h e n s i v e p r e d i c t i n g s t o p e spans i n j o i n t e d m a t e r i a l s d e s i g n methods of 34 ( K e r s t e n , 1 9 8 5 ) . Beam t h e o r i e s , n u m e r i c a l models and e m p i r i c a l c r i t e r i a have been employed i n the p a s t w i t h some d e g r e e of s u c c e s s . The major drawback i s t h a t most of our c l a s s i c a l d e s i g n a p p r o a c h e s have been b a s e d on a s s u m i n g t h a t homogeneous, i s o t r o p i c e l a s t i c c o n d i t i o n s e x i s t . S t o pe d e s i g n p r a c t i c e has ra n g e d from s o l u t i o n s i n v o l v i n g t r i a l and e r r r o r , r u l e of thumb, beam t h e o r i e s , to n u m e r i c a l m o d e l l i n g . R u l e of thumb a p p r o a c h e s such as the s t o p e span s h o u l d e q u a l o n e - h a l f t h e s t o p e h e i g h t ( M o r r i s o n , 1 9 7 6 ) , have e v o l v e d from f i e l d t r i a l s . The e l a s t i c beam and p l a t e s o l u t i o n s a r e b a s e d on c o n c e p t s d e r i v e d from s o l i d m e c h a n i c s ( E v a n s , 1 9 4 0 ) . They assume t h a t the r o c k above the e x c a v a t i o n behaves as a s e r i e s of e l a s t i c beams or p l a t e s l o a d e d by s e l f - w e i g h t and the r o o f span i s d e s i g n e d on the t e n s i l e s t r e n g t h of the beam. A f u r t h e r m o d i f i c a t i o n ( B e e r and Meek, 1982) to beam t h e o r y i s the " V o u s s o i r " beam which r e c o g n i z e s t h a t c r o s s j o i n t s may e x i s t w i t h i n the beam and c o n s e q u e n t l y , may not a l l o w any t e n s i l e s t r e s s e s to d e v e l o p . In a d d i t i o n , the V o u s s o i r beam t h e o r y assumes t h a t the beam c a r r i e s i t s w e i g h t by a r c h i n g , r e s u l t i n g i n a c o n f i n e d s i t u a t i o n . The b a s i c a s s u m p t i o n s common t o beam and V o u s s o i r t h e o r y a r e t h a t : - The gr o u n d above the h a n g i n g w a l l i s c o m p l e t e l y d e s t r e s s e d i n the d i r e c t i o n n o r m a l to the p l a t e ; - The r o c k mass has p a r t e d a l o n g smooth b e d d i n g p l a n e b r e a k s , f o r m i n g a s e r i e s of beams or p l a t e s . H o r i z o n t a l c o n f i n i n g s t r e s s e s may a l s o be i n c o r p o r a t e d i n 35 the above a n a l y s i s . I t i s b e l i e v e d t h a t the " V o u s s o i r Beam " t h e o r y has d e f i n i t e p o s s i b i l i t i e s i n p r e d i c t i n g s t o p e spans a t R u t t a n . The major l i m i t a t i o n may be the a s s u m p t i o n of e v e n l y d i s t r i b u t e d c r o s s - j o i n t s , w e l l d e f i n e d b e d d i n g p l a n e s and the use of e l a s t i c , homogeneous, i s o t r o p i c t h e o r y . P o s s i b l y a c o m b i n a t i o n of mass p r e d i c t e d s t r e n g t h s and " V o u s s o i r T h e o r y " may r e s u l t i n a more r e a l i s t i c s o l u t i o n , F i g u r e s 3.1,3.2. T h i s w i l l be f u r t h e r e v a l u a t e d i n C h a p t e r 9, " A p p l i c a t i o n s " . N u m e r i c a l m o d e l l i n g (Mathews e t a l , 1983) of mine o p e n i n g s would o u t l i n e the s t a t e of s t r e s s p r e s e n t a r o u n d the e x c a v a t i o n . R e l a t i n g the i n d u c e d s t r e s s to the r o c k mass s t r e n g t h would o u t l i n e p o s s i b l e f a i l u r e a r e a s . F i g u r e 3.3 o u t l i n e s t y p i c a l f a i l u r e modes t h a t may r e s u l t . A c o m b i n a t i o n of s t r u c t u r a l and s t r e s s c o n t r o l l e d f a i l u r e i s a l s o a p o s s i b l e mode of i n s t a b i l i t y . T h i s method of a n a l y s i s r e q u i r e s a c c u r a t e i n p u t i n t o the m odel, i n terms of the numerous p a r a m e t e r s a f f e c t i n g the s t a b i l i t y of the o p e n i n g . The d e s i g n e r i s o f f e r e d an i n v a l u a b l e t o o l i n c o m p a r i n g the s t a b i l i t y of one o p e n i n g r e l a t i v e to a n o t h e r c o n f i g u r a t i o n . In o r d e r to employ the r e s u l t s q u a n t i f i a b l y , computer v e r i f i c a t i o n t h r o u g h f i e l d o b s e r v a t i o n and measurements must be c o n d u c t e d . T h i s , however, i s not a l w a y s a p o s s i b i l i t y e s p e c i a l l y i n the p r e l i m i n a r y d e s i g n s t a g e s of a p r o p o s e d o p e r a t i o n . The use of a n a l y t i c a l methods i n s t o p e d e s i g n can b e s t be summarized by Mathews e t a l (1981) whereby " i n g e n e r a l , the number of v a r i a b l e s to be c o n s i d e r e d 3 6 i s t o o h i g h to p e r m i t o t h e r t h a n e m p i r i c a l a p p r o a c h e s to s t o p e d e s i g n . However, a n a l y t i c a l methods a r e o f t e n used t o i d e n t i f y e x c e s s i v e s t r e s s c o n d i t i o n s or e x c e s s i v e d e f o r m a t i o n s . " I n p u t p a r a m e t e r s , such as the r o c k mass m o d u l i , a r e g e n e r a l l y d e r i v e d from p e r f o r m i n g a r o c k mass e v a l u a t i o n . Rock mass c l a s s i f i c a t i o n s y s t e m s have e v o l v e d from the need to r e l a t e r o c k s u b s t a n c e p r o p e r t i e s to t h o s e of the j o i n t e d r o c k mass. Rock mass c l a s s i f i c a t i o n s p r o v i d e a common l a n g u a g e and c o n s e q u e n t l y , improve c o m m u n i c a t i o n s among a l l p e r s o n n e l c o n c e r n e d w i t h the s a f e e x t r a c t i o n of o r e . I t seems to overcome the p r o b l e m c a u s e d by the c o m p l e x i t y of the r o c k masses i n terms of q u a n t i f y i n g t h e i r p r o p e r t i e s . S e v e r a l r o c k mass c l a s s i f i c a t i o n s ystems have been d e v e l o p e d s i n c e T e r z a g h i (1946) p r o p o s e d h i s c l a s s i f i c a t i o n f o r the p r e d i c t i o n of r o c k l o a d on s t e e l a r c h d e s i g n . S e v e r a l r o c k mass c l a s s i f i c a t i o n s y s t e m s have been d e v e l o p e d and the f o l l o w i n g a r e the most w i d e l y u s e d : Deere ( 1 9 7 1 ) , RQD Wickham ( 1 9 7 4 ) , RSR B a r t o n (1976) , Q B i e n i a w s k i ( 1 9 7 3 ) , RMR A summary of the c o m p a r i s o n of the a p p l i c a t i o n of the r o c k mass c l a s s i f i c a t i o n s y s t ems r e v i e w e d i s shown i n T a b l e 3.1, w i t h l i m i t a t i o n s h i g h l i g h t e d i n T a b l e 3.2. A r e v i e w of the c r i t i c a l p a r a m e t e r s used f o r the major systems i s o u t l i n e d i n T a b l e 3.3. 37 Rock mass c l a s s i f i c a t i o n s have been s u c c e s s f u l l y employed i n the o v e r a l l d e s i g n of c i v i l e n g i n e e r i n g s t r u c t u r e s s i n c e the l a t e 1940's. I t i s o n l y r e c e n t l y t h a t t h i s s u c c e s s i s b e i n g t r a n s f e r r e d to m i n i n g r e l a t e d p r o b l e m s . L a u b s c h e r (1976) has d e v i s e d a m o d i f i e d r o c k mass r a t i n g p a t t e r n e d a f t e r the B i e n i a w s k i s y s t e m , w h i c h has been s u c c e s s f u l l y employed i n the d e s i g n of b u l k m i n i n g l a y o u t s . N i c h o l a s (1981) employs a c l a s s i f i c a t i o n s y s t e m i n o r d e r t o a i d i n the s e l e c t i o n of an optimum m i n i n g method by c h a r a c t e r i z i n g the f o o t w a l l , ore and h a n g i n g w a l l . K e n d o r s k i e t a l (1981) has p r o p o s e d a method of c l a s s i f i c a t i o n f o r c a v i n g o p e r a t i o n s . R e c e n t l y , s t u d i e s have been u n d e r t a k e n by Mathews e t a l (1981) whereby a m o d i f i e d NGI system has been employed to p r e d i c t e m p i r i c a l l y the d i m e n s i o n s of i s o l a t e d open s t o p e s a t d e p t h s below 1000 m e t r e s . C o n c l u s i o n s as s t a t e d by Mathews e t a l ( 1 9 8 1 ) , a r e as f o l l o w s : " R e s u l t s o b t a i n e d from the l i m i t e d d a t a a v a i l a b l e were c o n s i d e r e d s u f f i c i e n t to d e v e l o p the c o n c e p t s p r e s e n t e d , but i n s u f f i c i e n t to c o n f i r m them". The c l a s s i f i c a t i o n combines s e l e c t e d g e o t e c h n i c a l f a c t o r s i n t o a " s t a b i l i t y number" and p l o t s , F i g u r e 3.4, t h e s e v a l u e s a g a i n s t a "shape f a c t o r " w h i c h a c c o u n t s f o r the s i z e and shape of the s u r f a c e of the open s t o p e to be I n v e s t i g a t e d . These v a l u e s a r e e m p i r i c a l l y c a l i b r a t e d a g a i n s t open s t o p e d a t a o b t a i n e d from mine v i s i t s and l i t e r a t u r e ( 5 5 p o i n t s ) and a s s e s s e d i n terms of s t a b l e , p o t e n t i a l l y u n s t a b l e , and p o t e n t i a l l y c a v i n g r e g i o n s . The s t a b i l i t y number used a c c o u n t s f o r the r o c k mass q u a l i t y 38 ( Q ) , the s t a t e of s t r e s s and the o r i e n t a t i o n of e x p o s e d s u r f a c e s . I t i s e n v i s i o n e d to i n c o r p o r a t e the c o n c e p t s and expand on the s t u d y s i n c e i t s t r o n g l y p a r a l l e l s the s t u d i e s p r o p o s e d to be c o n d u c t e d a t R u t t a n . The m a j o r c r i t i c i s m of t h i s method i s the l i m i t e d number of c a s e s t u d i e s a c t u a l l y i n c o r p o r a t i n g s t o p e w a l l s , s i n c e o n l y s e v e n ( 7 ) c a s e s i n v o l v e d s t o p e w a l l s , the r e m a i n d e r were h o r i z o n t a l s t o p e b a c k s . The f o l l o w i n g p a r a m e t e r s were d i s c u s s e d : i - r e l a x a t i o n e f f e c t on t he HW or FW i s n o t f u l l y a s s e s s e d - b l a s t i n g e f f e c t s - e x c a v a t i o n r a t e - q u a n t i t a t i v e a s s e s s m e n t o f i n s t a b i l i t y - s t o p e c o n f i g u r a t i o n s o t h e r t h a n " i s o l a t e d " . - e f f e c t s of f i l l The methods of d e s i g n p a r t i c u l a r l y r e l e v a n t to the R u t t a n o r e b o d y w i l l be d i s c u s s e d i n s u b s e q u e n t c h a p t e r s on " R o c k Mass A s s e s s m e n t " , C h a p t e r 5 and " A p p l i c a t i o n " , C h a p t e r 9 . 3.3 Design Philosophy S tope spans a t R u t t a n had been b a s e d on the a s s u m p t i o n t h a t t he h a n g i n g w a l l a c t s as a s i m p l y s u p p o r t e d beam t h a t can bend o n l y to the p o i n t t h a t the s t r e n g t h of the i n t a c t r o c k w i l l a l l o w , F i g u r e 3 . 5 . The t e n s i l e s t r e s s e s c r e a t e d a t the c e n t r e of the beam, due to b e n d i n g , must be l e s s than the e x i s t i n g i n - s i t u t a n g e n t i a l ' c o m p r e s s i v e s t r e s s , i n o r d e r to 39 e n s u r e t h a t the beam i s i n c o n f i n e m e n t ( S m i t h , 1976) . S m i t h ' s d e s i g n was based on e x p e r i e n c e and t h e o r y a v a i l a b l e a t the time of the s t u d y . S u b s e q u e n t r e s e a r c h has shown t h a t t h e r e s u l t a n t s t r e s s a t m i d - s p a n i s t e n s i l e under the p r e v a i l i n g s t r e s s r e g i m e . The b a l a n c i n g of b e n d i n g s t r e s s e s t o the i n d u c e d t a n g e n t i a l s t r e s s e s must t a k e i n t o a c c o u n t the t h r e e d i m e n s i o n a l s t a t e of s t r e s s and r e s u l t a n t geometry of t h e o p e n i n g . The beam a p p r o a c h to a n a l y s i s , as d e s c r i b e d above, recommended two s t o p e l e n g t h s , the l o n g e r s t o p e l e n g t h b e i n g i n a r e a s h a v i n g a h i g h e r i n - s i t u t a n g e n t i a l s t r e s s . F i g u r e 2.13 o u t l i n e s the t y p i c a l s t o p e and r i b d i m e n s i o n s employed a t R u t t a n . The above method of d e s i g n was employed i n a l l r o c k t y p e s i r r e s p e c t i v e of the r o c k mass c o n d i t i o n s . The above a n a l y s i s was not a b l e to e x p l a i n l o c a l i n s t a b i l i t i e s t h a t o c c u r r e d , which g e n e r a l l y were due to the r e l e a s e of b l o c k s a l o n g e x i s t i n g s t r u c t u r e s . A d i f f e r e n t a p p r o a c h to s t o p e d e s i g n was i n c o r p o r a t e d i n 1983 by the a u t h o r whereby n u m e r i c a l m o d e l l i n g t e c h n i q u e s were augmented by a l a r g e e m p i r i c a l d a t a b a s e . T h i s forms the b a s i s f o r the d e v e l o p m e n t of a s o l u t i o n to the g o v e r n i n g h y p o t h e s i s s t a t e d i n C h a p t e r One. F i g u r e 3.6 i s a p l o t of s t r e s s t r a j e c t o r i e s f o r the mined out s t o p e s on the 320m l e v e l . T e n s i l e zones a r e e v i d e n t a d j a c e n t to most h a n g i n g and f o o t w a l l c o n t a c t s . The s i z e of the zone i s d e p e n d e n t upon the e x c a v a t i o n g e o m e t r y and the p r e v a i l i n g s t r e s s e s . V i s u a l o b s e r v a t i o n s a t the mine i n d i c a t e d t h a t the h a n g i n g w a l l and f o o t w a l l c o n t a c t s 40 a r e more f o l i a t e d i n c e r t a i n a r e a s t h a n o t h e r s . The r e s u l t was s l o u g h i n g a l o n g p r e f e r e n t i a l p l a n e s t h a t were not r e s t r a i n e d by a c o n f i n i n g s t r e s s , F i g u r e 3 . 7 . The absence of a c o n f i n i n g s t r e s s , c o u p l e d w i t h a f o l i a t e d w a l l c o n t a c t , e n a b l e s one t o a r r i v e a t a r e l a t i o n s h i p showing t h a t a h i g h e r d i l u t i o n r e s u l t s i n m i n i n g a s t o p e h a v i n g a p o o r e r "Rock Mass R a t i n g " . The R u t t a n o r e b o d y i s a m u l t i - l e n s e d e c h e l o n type d e p o s i t which r e q u i r e s one to d e t e r m i n e the i n f l u e n c e of m i n i n g geometry. S u f f i c i e n t l y l a r g e p i l l a r s s e p a r a t i n g i n d i v i d u a l s t o p e s would l i m i t t h i s e f f o r t . Mathews (1981) s u g g e s t s t h a t p i l l a r d i m e n s i o n s a l o n g s t r i k e s h o u l d e x c e e d the s t o p e span by at l e a s t 25%. P i l l a r s s e p a r a t i n g a d j a c e n t s t o p e s a t R u t t a n a r e o n l y 6m. i n l e n g t h w i t h s t o p e spans v a r y i n g from 40 to 50m. E m p l o y i n g t r i b u t a r y t h e o r y , i t had been shown t h a t the r i b p i l l a r s would e x h i b i t f a c t o r s of s a f e t y much l e s s t h an one. T h i s i n d i c a t e s t h a t the p i l l a r s a r e i n a s t a t e of p o s t - f a i l u r e , F i g u r e 3.8. The remnant p i l l a r e x h i b i t s s u f f i c i e n t r o c k mass s t r e n g t h to r e m a i n s t a n d i n g . " T h e p i l l a r s e p a r a t i n g a d j a c e n t s t o p e s may be c o n s i d e r e d as c r u s h e d , however, i t w i l l i n f l u e n c e the s t a b i l i t y of a d j a c e n t s t o p e s by i n c r e a s i n g the e f f e c t i v e s t o p e d i m e n s i o n s . P i l l a r s a t R u t t a n were o b s e r v e d to f a i l i n t h i s manner r a t h e r than by an u n c o n t r o l l e d v i o l e n t r e l e a s e of e n e r g y . Other f a c t o r s a f f e c t i n g s t o p e span t h a t must be i n v e s t i g a t e d a r e : 41 - B l a s t i n g - Rate of E x c a v a t i o n - G e o m e t r i c a l C o n f i g u r a t i o n of S t o p e s - E x c a v a t i o n Sequence - Depth Below S u r f a c e and, as p r e v i o u s l y d i s c u s s e d : - Rock Q u a l i t y ; p a r a m e t e r s as d e f i n e d as i n T a b l e 3.3 - A d v e r s e S t r u c t u r e - S t r e s s Regime; sequence of m i n i n g , f i l l A r t i f i c i a l s u p p o r t methods w i l l not be a d d r e s s e d i n t h i s t h e s i s , s i n c e R u t t a n does not employ any method of s t o p e s u p p o r t o t h e r t h a n f i l l . G r o undwater i s not c o n s i d e r e d to be a p r o b l e m a t t h i s s t a g e a t R u t t a n , s i n c e the d e p o s i t has been d e l i n e a t e d on 15m x 15m c e n t e r s , t h u s p r o v i d i n g a d e q u a t e d e p r e s s u r i z a t i o n , F i g u r e 2.11. T h i s w i l l be f u r t h e r d i s c u s s e d i n C h a p t e r 5, "Rock Mass A s s e s s m e n t " . The above w i l l be i n c o r p o r a t e d to d e t e r m i n e e m p i r i c a l s t o p e d e s i g n g u i d e l i n e s based on a s t a b i l i t y a s s e s s m e n t f o r each i n d i v i d u a l volume of e x c a v a t i o n . D i l u t i o n a t the R u t t a n o p e r a t i o n i s r e c o r d e d f o r each i n d i v i d u a l s t o p e a t v a r i o u s s t a g e s of e x c a v a t i o n . I t i s e n v i s i o n e d to employ t h i s v a l u e as an i n d i c a t o r of the s t a b i l i t y of the o p e n i n g . D i l u t i o n i s an i n d i r e c t i n d i c a t o r of the q u a n t i t y of s l o u g h o r i g i n a t i n g from the s t o p e w a l l s . The d a t a base i s c o m p r i s e d of f o r t y - t h r e e (43) s t o p e s a t v a r i o u s s t a g e s of e x t r a c t i o n , t h e r e b y y i e l d i n g 432 stope" g e o m e t r i e s . 42 3 . 4 Survey of Open Stope O p e r a t o r s A q u e s t i o n n a i r e ( P a k a l n i s , 1985) was d i s t r i b u t e d to t h i r t y - e i g h t ( 3 8 ) u n d e r g r o u n d base m e t a l mine o p e r a t i o n s t h r o u g h o u t Canada. I t was d e s i g n e d to a s s e s s the p r e s e n t s t a t e of knowledge w i t h r e s p e c t to s t o p e d e s i g n amongst mine o p e r a t o r s . The s e l e c t i o n c r i t e r i a f o r t h i s s t u d y were as f o l l o w s : - o n l y C a n a d i a n u n d e r g r o u n d base m e t a l o p e r a t i o n s were s u r v e y e d - the e x t r a c t i o n method had to i n c l u d e e i t h e r open s t o p i n g and/or room and p i l l a r - the d a i l y p r o d u c t i o n from u n d e r g r o u n d had to e x c e e d 1000 t o n n e s per day A l l u n d e r g r o u n d o p e r a t i o n s s a t i s f y i n g the above r e q u i r e m e n t s were c o n t a c t e d . The q u e s t i o n n a i r e was s e n t out i n March of 1985. Twenty-two(22) o p e r a t i o n s had r e s p o n d e d r e p r e s e n t i n g a 58% r e s p o n s e r a t e . The f o l l o w i n g a r e a s were i n v e s t i g a t e d by the ques t i o n n a i r e : a) Mine P r o f i l e : - P r o d u c t i o n r a t e -Maximum d e p t h of m i n i n g -Ore d i p , t y p e - M i n i n g Method b) G e o m e c h a n i c a l d a t a base t h a t i s a v a i l a b l e a t each 43 o p e r a t i o n : - R o c k s t r e n g t h p a r a m e t e r s - S t r e s s i n v e s t i g a t i o n s - R o c k mass p a r a m e t e r s - M o n i t o r i n g - I n s t r u m e n t a t i o n c ) S t o p e and P i l l a r d e s i g n , e v a l u a t e d i n te rms o f : - m e t h o d s e m p l o y e d - s u c c e s s of d e s i g n - s t o p e c h a r a c t e r i z a t i o n - r e s u l t a n t d i l u t i o n A copy of the q u e s t i o n n a i r e i s e n c l o s e d i n A p p e n d i x I. T a b l e 3.4 i d e n t i f i e s the i n d i v i d u a l o p e r a t o r s t h a t r e s p o n d e d to the q u e s t i o n n a i r e . P a r a m e t e r s t h a t a r e p a r t i c u l a r l y r e l e v a n t to the s c o p e of t h i s t h e s i s a r e s u m m a r i z e d w i t h i n t h i s s e c t i o n . 3.4.1 Mine P r o f i l e T w e n t y - t w o m i n i n g o p e r a t i o n s c o m p l e t e d and r e t u r n e d the e n c l o s e d q u e s t i o n n a i r e ( A p p e n d i x I ) . The s i z e d i s t r i b u t i o n of p a r t i c i p a t i n g o p e r a t i o n s i s shown i n F i g u r e 3 . 9 . The s m a l l e s t t o n n a g e p r o d u c e r r e s p o n d i n g was e q u i v a l e n t to 800 t p d . D i s t r i b u t i o n of m i n i n g method i n t e rms of p e r c e n t a g e of t o t a l t o n n a g e a t t r i b u t e d to t h a t method i s shown i n F i g u r e 3 .10 . ' - The c l a s s i f i c a t i o n of i n d i v i d u a l m i n i n g methods f o r the p u r p o s e s of t h i s s t u d y a r e as f o l l o w s : a) Open S t o p i n g M i n i n g Method 44 - b l a s t h o l e , l o n g h o l e ( I . T . H . ) - s u b - l e v e l s t o p l n g - v e r t i c a l c r a t e r r e t r e a t b) Room & P i l l a r M i n i n g Methods c) B a c k f i l l M i n i n g Methods - o v e r h a n d c u t & f i l l - u n d e r h a n d c u t & f i l l - m e c h a n i z e d c u t & f i l l d) O t h e r M i n i n g Methods - s h r i n k a g e - p i l l a r r e c o v e r y - d e v e l o p m e n t m i n i n g F i g u r e 3.10 i n d i c a t e s t h a t under the s e l e c t i o n c r i t e r i a s t a t e d p r e v i o u s l y , a p p r o x i m a t e l y 50% of the d a t a base i s composed of "open s t o p e o p e r a t o r s " . T h i s compares f a v o u r a b l y to a s u r v e y c o n d u c t e d by the O n t a r i o M i n i s t r y of L a b o u r (1985) t h a t i n d i c a t e d t h a t 51% of a l l ore p r o d u c t i o n by u n d e r g r o u n d m e t a l mines i n Canada i s d e r i v e d d i r e c t l y f r o m open s t o p i n g o p e r a t i o n s . M i n i n g d e p t h d i s t r i b u t i o n i s shown i n F i g u r e 3.11. The s h a l l o w e s t o p e r a t i o n i s a t 240 m, and the d e e p e s t a t 1250 m. M i n i n g d e p t h i s a c r i t i c a l f a c t o r i n d e t e r m i n i n g the i n - s i t u s t r e s s t h a t may be e n c o u n t e r e d d u r i n g m i n i n g . In a d d i t i o n , a t each d e p t h i n t e r v a l the d i s t r i b u t i o n of p r o d u c t i o n , i n terms of tonnage a t t r i b u t e d to e a c h method d i v i d e d by the t o t a l tonnage f o r t h a t p a r t i c u l a r method, was d e t e r m i n e d ( i e . between 300-600 m d e p t h , 17% of the t o t a l open s t o p e p r o d u c t i o n i s m i n e d ) . 45 3.4.2 Rock Mechanics S i g n i f i c a n t a d v a n c e s have o c c u r r e d i n the s c i e n c e of r o c k m e c h a n i c s t h r o u g h o u t the p a s t twenty y e a r s . These have i n c l u d e d the d e v e l o p m e n t of c o m p r e h e n s i v e f a i l u r e c r i t e r a f o r i n t a c t and f r a c t u r e d r o c k , s o p h i s t i c a t e d computer codes f o r m o d e l l i n g r o c k s t r u c t u r e s , and i n d e t e r m i n a t i o n of r o c k p r o p e r t i e s . In a d d i t i o n , advances, i n i n s t r u m e n t a t i o n have e n a b l e d the o p e r a t o r to more p r e c i s e l y d e t e r m i n e the p r e v a i l i n g i n - s i t u s t r e s s . In terms of m o n i t o r i n g , a d v a n c e d e a r l y w a r n i n g systems have been d e v e l o p e d , and a r e , In a d d i t i o n , b e i n g used i n the c a l i b r a t i o n of the d e s i g n p r o c e s s . The l e v e l of r o c k m e c h a n i c s a c t i v i t y i n t h i s a r e a has been i n v e s t i g a t e d t h r o u g h the q u e s t i o n n a i r e . F i g u r e 3.12 shows the d i f f e r e n t i n t a c t r o c k s t r e n g t h p r o p e r t i e s t h a t have been i n v e s t i g a t e d by the p a r t i c i p a t i n g m i n e s . The f o l l o w i n g p a r a m e t e r s have been r e f e r r e d to : - u n i t w e i g h t (UW) - e l a s t i c modulus ( E ) , P o i s s o n ' s r a t i o (V) - u n c o n f i n e d c o m p r e s s i v e s t r e n g t h ( U C S ) , t e n s i l e s t r e n g t h ( T S ) , i n t e r n a l f r i c t i o n a n g l e , t r i a x i a l t e s t i n g ( T R ) , s l i d i n g a n g l e of f r i c t i o n (SS) -employment of a f a i l u r e c r i t e r i o n to e s t i m a t e the r o c k s t r e n g t h (FC) 46 F i g u r e 3.13 o u t l i n e s the p e r c e n t u t i l i z a t i o n of n u m e r i c a l m o d e l i n g f o r mine d e s i g n . In a d d i t i o n , i t shows t h a t i n - s i t u s t r e s s measurement has been c o n d u c t e d i n 85% of the mine o p e r a t i o n s . These two t e c h n i q u e s a r e o f t e n a s s o c i a t e d , i n t h a t the v i r g i n s t r e s s Is a c r i t i c a l i n p u t p a r a m e t e r f o r n u m e r i c a l m o d e l l i n g . P h o t o - e l a s t i c methods of m o d e l l i n g were n o t u s e d . The d i s t r i b u t i o n of s t r e s s e s a r o u n d u n d e r g r o u n d o p e n i n g s c o u p l e d w i t h the r o c k s t r e n g t h p a r a m e t e r s , i s an i n d i c a t o r of i n s t a b i l i t y . Rock mass c l a s s i f i c a t i o n s have e v o l v e d from the need to r e l a t e the r o c k s u b s t a n c e p r o p e r t i e s t o t h o s e of the j o i n t e d r o c k mass. F i g u r e 3.14 shows t h a t s t r u c t u r a l mapping i s c o n d u c t e d by a l l o p e r a t i o n s , w i t h D e e r e ' s (1964) RQD c l a s s i f i c a t i o n b e i n g the most w i d e l y u s e d . The f o l l o w i n g were the c l a s s i f i c a t i o n s y s t e m s s u r v e y e d : -Rock Q u a l i t y D e s i g n a t i o n ( R Q D ) - D e e r e ( 1 9 6 4 ) -Q system - B a r t o n e t a l ( 1 9 7 4 ) -RMR s y s t e m - B i e n i a w s k i (1973) - M o d i f i e d RMR system - L a u b s c h e r ( 1 9 7 4 ) The c l a s s i f i c a t i o n s y s t e m c o u p l e d w i t h the l a b o r a t o r y s t r e n g t h r e s u l t s e n a b l e s the o p e r a t o r to a s s e s s the p r o p e r t i e s of the r o c k mass. 3.4.2.1 Stope and P i l l a r D esign The p r o b l e m s of e s t i m a t i n g " c r i t i c a l s t o p e s p a n s " and 47 " p i l l a r dimensions" are complex. This i s because the rock mass behaviour i s dependent upon a l a r g e number of i n t e r - r e l a t e d v a r i a b l e s such as the rock mass q u a l i t y , s t r e s s d i s t r i b u t i o n , and the mine geometry among o t h e r s . S e v e r a l p i l l a r ( P o t v i n , 1985) and opening design methods have been developed ( P a k a l n i s , 1985). This report c l a s s i f i e s the methods i n the f o l l o w i n g c a t e g o r i e s : - E m p i r i c a l methods; such as those derived from a l a r g e data base, i e . Hedley p i l l a r formula (1972) - A n a l y t i c a l s o l u t i o n s ; such as beam theory i n the design o f s t o p e s p a n s - P r a c t i c a l e x perience; o b s e r v a t i o n a l approaches -Numerical modelling methods; such as boundary element, f i n i t e element codes Figure 3.15 i n d i c a t e s that a l l mines i n the data base u t i l i z e p r a c t i c a l experience i n t h e i r design f o l l o w e d by e m p i r i c a l and numerical techniques of m o d e l l i n g . Figure 3.15, however, shows that only 34% of the mines r e l y s o l e l y on p r a c t i c a l experience as t h e i r main input to d e s i g n . The most widely used combination was that employing p r a c t i c a l and e m p i r i c a l experience as well as computer modelling d e r i v e d r e s u l t s . The term " p r a c t i c a l " r e f e r s t o t r i a l - a n d - e r r o r approaches, whereas e m p i r i c a l r e f e r s to p i l l a r and stope formulae as d e r i v e d throughout the l i t e r a t u r e . 48 3.4 . 3 D i l u t i o n Assessment D i l u t i o n i s a measure of e x t e r n a l was te t h a t has s l o u g h e d I n t o the d r a w p o i n t . S t o p e d i l u t i o n as e s t i m a t e d by the p a r t i c i p a t i n g mine o p e r a t o r s , i s a q u a n t i t a t i v e p a r a m e t e r t h a t e n a b l e s the o p e r a t o r to e v a l u a t e the q u a l i t y of h i s d e s i g n . The f o l l o w i n g a r e the most common methods of e s t i m a t i n g d i l u t i o n as I n d i c a t e d by the q u e s t i o n n a i r e : -% D i l u t i o n = ( w e i g h t of e x t e r n a l s l o u g h x 100 ) / ( w e i g h t of o re r e s e r v e s ) - D i l u t i o n = ( u n d i l u t e d i n p l a c e g r a d e (DDH) ) / ( s a m p l e a s s a y g r a d e a t d r a w p o i n t ) - D i l u t i o n = ( u n d i l u t e d i n p l a c e g r a d e r e s e r v e s ) / ( m i l l head g r a d e s o b t a i n e d f o r same t o n n a g e ) - D i l u t i o n = ( t o t a l was te t o n n a g e ) / ( t o t a l t o n s m ined ) - D i l u t i o n = ( t o t a l waste m i n e d ) / ( t o n s of o r e r e s e r v e s es t i m a t e d ) - d i f f e r e n c e be tween t o n n a g e mucked and t h a t b l a s t e d - d i f f e r e n c e be tween t o n n a g e of b a c k f i l l p l a c e d and t h a t t h e o r e t i c a l l y r e q u i r e d to f i l l " o r e r e s e r v e s " v o i d - d i l u t i o n i s v i s u a l l y o b s e r v e d and a s s e s s e d - " x " amount of f e e t i n the f o o t w a l l p l u s " y " amount of f e e t i n the h a n g i n g w a l l d i v i d e d by the s t o p e w i d t h - h i s t o r i c a l a v e r a g e o v e r p a s t 10 y e a r s = a c t u a l tons drawn f rom s t o p e s / c a 1 c u 1 a t e d r e s e r v e t o n n a g e The l e v e l of a c c e p t a b l e d i l u t i o n i s h i g h l y d e p e n d e n t upon g r a d e s i n c e a h i g h e r g r a d e s t o p e can be e c o n o m i c a l , whereas a 49 l o w e r grade s t o p e w i t h the same d i l u t i o n w i l l no l o n g e r be m i n e a b l e . I t i s p r o p o s e d t h a t the f o l l o w i n g t h r e s h o l d s be employed f o r c o m p a r a t i v e p u r p o s e s : - l e s s t h a n 10% d i l u t i o n -10 - 19% d i l u t i o n -20 - 35% d i l u t i o n - g r e a t e r than 35% d i l u t i o n The n o n - e n t r y methods of m i n i n g , s u c h as open s t o p i n g , can a c c e p t a c e r t a i n d e g r e e of w a l l s l o u g h w i t h o u t i n j u r y to the w o r k e r s . F i g u r e 3.16 shows the amount of d i l u t i o n as d e t e r m i n e d by the open s t o p e o p e r a t o r s . The p e r c e n t o c c u r r e n c e was measured as the number of o p e r a t i o n s e x h i b i t i n g an a v e r a g e d i l u t i o n d i v i d e d by the t o t a l number of o p e r a t i o n s i n the d a t a b a s e . The open s t o p e d i l u t i o n s t a t i s t i c s r e v e a l t h a t 47% of a l l open s t o p e o p e r a t i o n s have more t h a n 20% d i l u t i o n . I t was g e n e r a l l y s t a t e d by the o p e r a t o r s t h a t d i l u t i o n s under 5% a t e a c c e p t a b l e and were c l a s s i f i e d as low. T h i s i s c o n s i d e r e d n o r m a l due to r e c o r d i n g a c c u r a c y , b l a s t i n g e f f e c t s , and v a r i a b i l i t y i n the o r e geometry and i n the r o c k mass s t r e n g t h s . 3 . 4 . 4 Stope C h a r a c t e r i z a t i o n by The i n d i v i d u a l mine o p e r a t i o n s "Rock Mass R a t i n g " , t h i s i s shown were f u r t h e r c a t e g o r i z e d by F i g u r e 3.17 and T a b l e 50 3.5. The r o c k mass a s s e s s m e n t was c o n d u c t e d as shown i n the q u e s t i o n n a i r e . T h i s c a t e g o r i z a t i o n of the r o c k mass i n terms of s t r e n g t h , RQD, s p a c i n g and j o i n t c o n d i t i o n were as d e f i n e d by N i c h o l a s ( 1 9 8 1 ) . T h i s system was employed due to i t s s i m p l i c i t y and s i m i l a r i t y to the RMR s y s t e m which i s d e s c r i b e d i n s u b s e q u e n t c h a p t e r s . A p p e n d i x I shows the r e l a t i o n s h i p employed between the two s y s t e m s . N i c h o l a s had p r o p o s e d a c l a s s i f i c a t i o n s y stem f o r the s e l e c t i o n of an o p t i m a l m i n i n g method g i v e n the f o l l o w i n g c o n s t r a i n t s : - g e o m e t r i c c o n s i d e r a t i o n s - r o c k m e c h a n i c s c o n s i d e r a t i o n s I t was i n t e n d e d to d e l i n e a t e t h o s e m i n i n g methods t h a t w i l l be most e f f e c t i v e g i v e n the above c o n s t r a i n t s . N i c h o l a s s u g g e s t e d the f o l l o w i n g c o n d i t i o n s be p r e s e n t i f an open s t o p e method i s to be c o n s i d e r e d : - r o c k s u b s t a n c e s t r e n g t h In the h a n g i n g w a l l and the ore zone to be a t l e a s t of moderate s t r e n g t h , wide s p a c i n g , and m oderate j o i n t c o n d i t i o n . The g r o u n d w a t e r r a t i n g was a s s e s s e d as d r y f o r a l l o p e r a t i o n s c o n s i d e r e d . T h i s was due t o : a) the d i f f i c u l t y i n e s t i m a t i n g water p r e s s u r e s d u r i n g l o g g i n g of c o r e , b) most mine w o r k i n g s a r e d e p r e s s u r i z e d due to the p r e s e n c e of e x p l o r a t o r y d r i l l h o l e s , d e v e l o p m e n t h e a d i n g s e t c . U n l e s s i n d i c a t e d 51 o t h e r w i s e by the mine o p e r a t o r , the g r o u n d w a t e r r a t i n g was a s s e s s e d as "RMR=10". T h i s was a l s o f o u n d to be the c a s e i n the O n t a r i o M i n i s t r y of L a b o u r s u r v e y (1985) where g r o u n d w a t e r , F i g u r e 3.18, was f o u n d t o be of l i t t l e or no c o n c e r n to open s t o p e o p e r a t o r s e x c e p t i n the v i c i n i t y of the crown p i l l a r . The r o c k q u a l i t y of the h a n g i n g w a l l was a s s e s s e d f o r open s t o p e o p e r a t o r s . T h i s i s due to the r e a s o n i n g t h a t most of the d i l u t i o n i s p r o b a b l y from the a d j a c e n t o v e r h a n g . Cases where l o w e r f o o t w a l l RMR r a t i n g s p r e v a i l e d r e q u i r e d one to a s s e s s the s t o p e c h a r a c t e r i z a t i o n i n d i v i d u a l l y . T h i s s i t u a t i o n d i d n ot o c c u r . The o r e RMR was e v a l u a t e d f o r c h a r a c t e r i z a t i o n of p i l l a r s f o r open s t o p e o p e r a t i o n s , T a b l e 3.6. A p pendix I o u t l i n e s the t e r m i n o l o g y employed i n i d e n t i f y i n g s t o p e and p i l l a r d i m e n s i o n s . 3.4.4.1. Stope Assessment The exposed s u r f a c e a r e a was f u r t h e r a n a l y s e d i n terms of h y d r a u l i c r a d i u s . Mathews e t a l (1981) have a t t e m p t e d to r e l a t e the r o c k q u a l i t y f o r open s t o p e s i n terms of the a r e a of w a l l e x p o s e d . The term " h y d r a u l i c r a d i u s " i s employed which i s d e f i n e d by the e x p o s e d s u r f a c e a r e a / s u r f a c e p e r i m e t e r . T h i s v a l u e t e n d s to i n c o r p o r a t e the s t o p e c o n f i g u r a t i o n as w e l l as the s i z e ; i e . o p e n i n g s whose l o n g span to s h o r t span exceed a p p r o x i m a t e l y f o u r t o one have mino r v a r i a t i o n s i n h y d r a u l i c r a d i u s w i t h i n c r e a s e d span and t h e r e f o r e r e p r e s e n t one way s p a n n i n g g e o m e t r i e s ( t u n n e l ) . 52 Open s t o p e d i m e n s i o n s f o r the d a t a base a r e shown i n F i g u r e 3.19. A f u r t h e r a n a l y s i s was c o n d u c t e d f o r the l a r g e r open s t o p e d a t a base (24 s t o p e s ) t h a t compared the f o l l o w i n g p a r a m e t e r s i n o r d e r to d e t e r m i n e i f a c o r r e l a t i o n e x i s t e d : a) f i l l / n o f i l l v s . d e p t h F i g u r e 3.2 i n d i c a t e s t h a t 69% of open s t o p e o p e r a t o r s employ f i l l . T h e r e was f o u n d to be no c o r r e l a t i o n between m i n i n g d e p t h and f i l l o p t i o n ( f i l l / n o f i l l ) . b) d i l u t i o n v s . RMR The a v e r a g e d i l u t i o n was 19% - 1 5 % The a v e r a g e RMR v a l u e was 53% * 16% C o r r e l a t i o n was: r= -.74 ( h i g h l y s i g n i f i c a n t a t the 99% l e v e l ) c) d i l u t i o n ' v s . s t o p e d e p t h The a v e r a g e s t o p e d e p t h was 388m - 237m C o r r e l a t i o n was: r=+.23 ( n o t s i g n i f i c a n t a t 90% l e v e l ) d) d i l u t i o n v s . h y d r a u l i c r a d i u s ( H R ) The a v e r a g e h y d r a u l i c r a d i u s was 10.5m -4.2m C o r r e l a t i o n was: r=-.26 ( n o t s i g n i f i c a n t a t 90% l e v e l ) e) d i l u t i o n v s . e x p o s e d s u r f a c e a r e a The a v e r a g e e x p o s e d s u r f a c e a r e a was 2751 m2 - 2213m 2 C o r r e l a t i o n was: r=-.29 ( n o t s i g n i f i c a n t a t 90% l e v e l ) f ) d i l u t i o n v s . RMR,HR M u l t i p l e c o r r e l a t i o n i s : r= .8 ( h i g h l y s i g n i f i c a n t a t the 99% l e v e l , s l i g h t improvement o v e r b) g) d i l u t i o n v s . s t o p e depth,RMR M u l t i p l e c o r r e l a t i o n i s : r= .75 ( h i g h l y s i g n i f i c a n t a t the 99% l e v e l , no - improvement -over b) 53 The above l i n e a r c o r r e l a t i o n c o e f f i c i e n t s i n d i c a t e t h a t the o n l y p a r a m e t e r d i r e c t l y c o r r e l a t i v e to d i l u t i o n i s the r o c k q u a l i t y . A c o m b i n a t i o n of i n d i v i d u a l p a r a m e t e r s would be a b e t t e r e s t i m a t e of d i l u t i o n as shown by e) RMR, h y d r a u l i c r a d i u s but not i n f ) s t o p e d e p t h , RMR. 3 . 4 . 4 . 2 . P i l l a r Assessment A f u r t h e r a n a l y s i s was a l s o c o n d u c t e d on the r i b p i l l a r s as shown i n F i g u r e 3.21 f o r the open s t o p i n g o p e r a t i o n s ( d a t a base = 24 s t o p e s ) . The f o l l o w i n g were compared: a) RMR v s . Lp/Wp The mean RMR=67 - 20 The mean Lp/Wp = 3 . 9 - 3 . 4 C o r r e l a t i o n : r = 0.08 (no c o r r e l a t i o n ) b) RMR v s . Lp/Lo The mean Lp/Lo=.8 ± .5 C o r r e l a t i o n : r = + . 3 6 ( n o t s i g n i f i c a n t a t 95% l e v e l ) c) Stope d e p t h v s . Lp/Wp C o r r e l a t i o n : r = - . 2 6 ( n o t s i g n i f i c a n t a t 95% l e v e l ) d) Stope d e p t h v s . Lp/Lo C o r r e l a t i o n : r = - . 3 3 ( n o t s i g n i f i c a n t a t 95% l e v e l ) The v a r i a b l e s i n v e s t i g a t e d were f o u n d not to be c o r r e l a t i v e a t the 95% s i g n i f i c a n c e l e v e l . T h i s i s p o s s i b l y due to the many v a r i a b l e s I n v o l v e d i n the e s t i m a t i o n of p i l l a r g e o m e t r y . In 54 a d d i t i o n , i t was not p o s s i b l e to d e t e r m i n e the s t a t e of p i l l a r d i s t r e s s whereas d i l u t i o n i s a q u a n t i t a t i v e measure of o p e n i n g i n s t a b i l i t y . 3.4.5. Observations H i s t o r i c a l l y C a n a d i a n u n d e r g r o u n d mines have been d e s i g n e d b a s e d on e x p e r i e n c e , and o p t i m i z e d t h r o u g h a t r i a l - a n d - e r r o r p r o c e s s . T h i s a p p r o a c h i n the l o n g term can l e a d to an optimum mine l a y o u t , however, the r e a l c o s t of such p r o c e d u r e s can o f t e n be measured i n terms o f : - i n j u r i e s to the worker - d i l u t i o n - a d d i t i o n a l a r t i f i c i a l s u p p o r t r e q u i r e m e n t s - p r o d u c t i o n d e l a y s a n d / o r i s o l a t i o n of o r e due t o i n s t a b i l i t y The d e g r e e of r o c k m e c h a n i c s d a t a a v a i l a b l e a t the i n d i v i d u a l mine o p e r a t i o n s s u r v e y e d s u g g e s t e d t h a t ground c o n t r o l i s an i n t e g r a l p a r t of the mine d e s i g n p r o c e s s . There i s no s i n g l e a c c e p t e d method of d e s i g n i n j o i n t e d m a t e r i a l s , as i s shown by the v a r i a b i l i t y i n d e s i g n m e t h o d o l o g y and the e x c e p t i o n a l l y h i g h l e v e l s of r e c o r d e d d i l u t i o n . The r o c k q u a l i t y was f o u n d to be s t r o n g l y c o r r e l a t e d to d i l u t i o n i n terms of o p e n i n g d e s i g n and c o n s e q u e n t l y , s h o u l d p l a y an i m p o r t a n t r o l e i n the d e s i g n p r o c e s s . V a l u e s f o r Lp/Lo and Lp/Wp f o r open s t o p e o p e r a t i o n s a v e r a g e d .8 - .5 and 3.91 55 3.4 r e s p e c t i v e l y . T h i s was d e t e r m i n e d o v e r an a v e r a g e d e p t h of 388m - 237m. C o r r e l a t i o n s among the p i l l a r v a r i a b l e s were p o o r . T h i s i s p a r t l y due to the d i f f i c u l t y i n e s t i m a t i n g the s t a t e of p i l l a r d i s t r e s s , whereas d i l u t i o n i s a q u a n t i t a t i v e p a r a m e t e r and more e a s i l y d e t e r m i n e d . F i g u r e 3.18 summarizes the ground c o n t r o l p r o b l e m s i d e n t i f i e d by the O n t a r i o s u r v e y of C a n a d i a n o p e r a t o r s . The O n t a r i o M i n i s t r y of L a b o u r s p o n s o r e d a s t u d y whereby i n f o r m a t i o n was o b t a i n e d from a p p r o x i m a t e l y 65 base m e t a l u n d e r g r o u n d C a n a d i a n m i n e s . T h i s r e p r e s e n t s most of the o p e r a t i n g C a n a d i a n mines a t the time of the s u r v e y (March 1 9 8 5 ) . The q u e s t i o n n a i r e was c o m p l e t e d by c o n t a c t i n g the i n d i v i d u a l mines or group of mines by t e l e p h o n e . The f o l l o w i n g i s a breakdown of the i n d i v i d u a l mine o p e r a t o r s : -open s t o p i n g 31 mines - c u t & f i l l 23 mines - c a v i n g 4 mines -room & p i l l a r 7 mines T o t a l 65 mines 3.5 Conclusions T h i s s u r v e y a l o n g w i t h the O n t a r i o ( 1 9 8 5 ) s t u d y i n d i c a t e d t h a t d i l u t i o n i s of p a r t i c u l a r c o n c e r n to open s t o p i n g o p e r a t o r s . N e i t h e r backs nor p i l l a r s w i l l be a d d r e s s e d i n t h i s the s i s s i n c e : - the o b s e r v e d d i l u t i o n a t R u t t a n i s s o l e l y a measure of the h a n g i n g w a l l and f o o t w a l l s l o u g h - d e t e r i o r a t i o n of s t o p e backs and p i l l a r s has caused o n l y minor p r o b l e m s a t R u t t a n 56 I t i s r e a l i z e d t h a t back and p i l l a r s t a b i l i t y i s an i m p o r t a n t d e s i g n r e q u i r e m e n t . The a u t h o r must l i m i t the s cope of t h i s s t u d y to the f a c t o r s a f f e c t i n g " w a l l s l o u g h " a t R u t t a n . Mechan i sms o t h e r than r e l a x a t i o n may p r e v a i l and c o n s e q u e n t l y , may r e q u i r e a p r o c e d u r e of d e s i g n d i f f e r e n t t h a t t h a t s u g g e s t e d i n t h i s s t u d y . The d e s i g n methods t h a t a r e a v a i l a b l e f o r a s s e s s i n g the s t a b i l i t y of mine o p e n i n g s can be c a t e g o r i z e d as f o l l o w s : a) A n a l y t i c a l b) O b s e r v a t i o n a l c ) E m p i r i c a l A n a l y t i c a l methods a r e b a s e d on the a n a l y s e s of s t r e s s e s and d e f o r m a t i o n s a r o u n d o p e n i n g s . O b s e r v a t i o n a l methods r e l y on the m o n i t o r i n g of g r o u n d movement d u r i n g m i n i n g to d e t e c t m e a s u r e a b l e i n s t a b i l i t y . E m p i r i c a l methods a s s e s s the s t a b i l i t y of m ines by the use of s t a t i s t i c a l a n a l y s e s of u n d e r g r o u n d o b s e r v a t i o n s . A n a l y t i c a l methods a r e p r i m a r i l y e m p l o y e d f o r c o m p a r a t i v e d e s i g n and p a r a m e t r i c s t u d i e s . The o b s e r v a t i o n a l a p p r o a c h would r e q u i r e a l a r g e d a t a b a s e and wou ld have to be i m p l e m e n t e d i n the i n i t i a l s t a g e s of mine d e v e l o p m e n t i n o r d e r to a c h i e v e some r e l i a b l e measurement of o p e n i n g s t a b i l i t y . The R u t t a n o r e b o d y i s i n an a d v a n c e d s t a g e of e x t r a c t i o n and c o n s e q u e n t l y , o b s e r v a t i o n a l methods a r e of l i m i t e d use i n p r e d i c t i n g h a n g i n g w a l l or f o o t w a l l d i m e n s i o n s i n v a r i o u s r o c k t y p e s and s t o p e c o n f i g u r a t i o n s . B i e n i a w s k i ( 1985) s t a t e s t h a t i n 57 o r d e r to meet the i m m e d i a t e n e e d s of the mine p r a c t i o n e r , s t u d i e s s h o u l d be d i r e c t e d to the d e v e l o p m e n t o f e m p i r i c a l f a i l u r e c r i t e r i a . J a e g e r and Cook (1979) s u g g e s t t h a t a f a i l u r e c r i t e r i a has y e t to be d e v e l o p e d t h a t d e s c r i b e s the a c t u a l mechan i sm of f r a c t u r e and t h a t e m p i r i c a l e q u a t i o n s f i t the e x p e r i m e n t a l r e s u l t s much b e t t e r . B i e n i a w s k i s u g g e s t s t h a t s u c h c r i t e r i a can be s e l e c t e d by f i t t i n g a s u i t a b l e e q u a t i o n to e x p e r i m e n t a l d a t a w h i c h do n o t n e c e s s a r i l y r e q u i r e a t h e o r e t i c a l b a s i s . The e m p i r i c a l r e l a t i o n w i l l s e r v e to meet the r e q u i r e m e n t s o f a d e q u a t e p r e d i c t i o n , s i m p l i c i t y o f use and s p e e d of a p p l i c a t i o n . I t i s t h e r e f o r e p r o p o s e d to emp loy an e m p i r i c a l l y b a s e d a p p r o a c h t h a t e v a l u a t e s the p a r a m e t e r s t h a t may have an i n f l u e n c e on h a n g i n g and f o o t w a l l s t a b i l i t y d e s i g n and u l t i m a t e l y d e v e l o p a r e l a t i o n w h e r e b y : Z = A + Bx + Cy + Du + . . . . o r Z = A + Bx + Cy + D x 2 + E y 2 + Fxy + . . . . whe re : Z: r e f e r s t o the c o n t r o l v a r i a b l e w h i c h Is q u a n t i f i a b l e and w i l l be f o r t h i s s t u d y " D i l u t i o n " A , B , C , . . . : a r e c o n s t a n t s d e t e r m i n e d by r e g r e s s i o n a n a l y s i s p e r f o m e d on a l i n e a r h y p e r - s u r f a c e o r q u a d r a t i c s u r f a c e x : r e f e r s to the d i m e n s i o n s of the h a n g i n g w a l l o r f o o t w a l l y , u , v . . . . : r e f e r s to the v a r i a b l e s t h a t a re c r i t i c a l t o . t h e ' e v a l u a t i o n . 58 The b e s t f i t w i l l be e v a l u a t e d i n terms of a s t a t i s t i c a l r e g r e s s i o n a n a l y s i s p e r f o r m e d on l i n e a r and q u a d r a t i c e q u a t i o n s . The c o r r e l a t i o n s and p r o b a b i l i t y t h e o r y w i l l d e t e r m i n e the a c c e p t a n c e or r e j e c t i o n of the h y p o t h e s i s . A r e j e c t i o n of the h y p o t h e s i s would n o t e n a b l e an e m p i r i c a l e q u a t i o n to be e s t i m a t e d whereas an a c c e p t a n c e would s u g g e s t t h a t an e m p i r i c a l f o r m u l a t i o n may be p o s s i b l e . 59 T a b l e 3 . 1 : Rock Mass C l a s s i f i c a t i o n S y s t ei I I S - A p p l i c a t i o n s NOTE: In order for method to be c las s i f ied as having a mining appl icat ion, i t must have been referenced in the l i tera ture . CLASSIFICATION APPLICATIONS I TERZAGHI | I LAUFFER-PACHER I DEERE oc m oc oc oc o I KIRSTEN LOUIS FRANKLIN COATES I PARSONS > UJ _J => CO LAUBSCHER KENDORSKI HcMAHON MATHEWS c 3E o r UJ _J _J ri X I COAL CLASSIFIC MINING APPLICATIONS MINING METHOD SELECTION X *X K X X MINING APPLICATIONS MINE SEQUENCING X MINING APPLICATIONS STANO-UP TIME X X X X MINING APPLICATIONS MAX. UNSUPPORTED SPAN X X X X X X MINING APPLICATIONS SUPPORT DESIGN X X X X X K X MINING APPLICATIONS PILLAR DESIGN X X X X MINING APPLICATIONS CAVABILITY X X X X MINING APPLICATIONS CAVE ANGLE X MINING APPLICATIONS ROOF STABILITY X X X X X MINING APPLICATIONS FLOOR STABILITY X X X X MINING APPLICATIONS OPEN STOPE DESIGN X X X X MINING APPLICATIONS ROCK LOAD X X X X X MINING APPLICATIONS RIPPABILITY X X ROCK MASS STRENGTH INDICES COHESION X X X X ROCK MASS STRENGTH INDICES FRICTION ANGLE X X X X ROCK MASS STRENGTH INDICES DEFORMATION MODULUS X X X X ROCK MASS STRENGTH INDICES STRENGTH X X X X CIVIL APPLICATIONS ROCK LOAD X X X X X X X CIVIL APPLICATIONS STAND-UP TIME X X X X CIVIL APPLICATIONS MAX. UNSUPPORTED SPAN X X X X X X X CIVIL APPLICATIONS SUPPORT DESIGN X X > X X X X X X X CIVIL APPLICATIONS FOUNDATION DESIGN X X X CIVIL APPLICATIONS SLOPE DESIGN X X X CIVIL APPLICATIONS T a b l e 3.2: L i m i t a t i o n s o f the M a j o r Rock Mass C l a s s i f i c a t i o n Systems - M i n i n g A p p l i e d 1 CLASSIFICATION DOES NOT CONSIDER ^ ^ \ C L A S S I F I C A T I O N LIMITATIONS X u GC UJ •— DEERE oc t / i oc oc z ac Q KIRSTEN UL X U) l/l CO 3 KENDORSKI HcMAHON HATHEWS NICHOLAS 1 CLASSIFICATION DOES NOT CONSIDER STRESS FIELD X X X X 1 CLASSIFICATION DOES NOT CONSIDER JOINT CONDITION X X 1 CLASSIFICATION DOES NOT CONSIDER CONTINUITY X X X 1 CLASSIFICATION DOES NOT CONSIDER JOINT ORIENTATION X X X X X X 1 CLASSIFICATION DOES NOT CONSIDER JOINT INFILLING X X X 1 CLASSIFICATION DOES NOT CONSIDER SWELLING MATERIAL X X X X 1 CLASSIFICATION DOES NOT CONSIDER BLASTING EFFECT X X X X X X X X X 1 CLASSIFICATION DOES NOT CONSIDER UNIAXIAL COMPRESSIVE STRENGTH X X X X 1 CLASSIFICATION DOES NOT CONSIDER EXCAVATION METHOD X X X X X X 1 CLASSIFICATION DOES NOT CONSIDER GROUNDWATER X X X CLASSIFICATION REQUIRES STRESS\FIELD < 30MF-A "7 T X CLASSIFICATION REQUIRES EXTENSIVE EXPERIENCE X X X CLASSIFICATION REQUIRES MORE FIELD EXPERIMENTATION X x X X X X CLASSIFICATION REQUIRES ENVIRONMENT . ROCK MASS JOINTING ROCK MATERIAL WE f— o m x c> m o o r> o z » > ? m (-» J> a <-> 5> m z z 3> 2C o z m Tl RO m 3 a •<: z - c z 2 °, m ^ t> X o ?o - o n / 30 o CD -< c : CT •H JC - H f— > —A c r z CD 30 o c 5» MAS: OPER Z o —i CT m O «H O —( O Z -H O Tl 3> f— 1— MAS: OPER m O 3C m —H 30 -< o 33 m z -H J> —4 O z 1 METHOD | 3D 1 STRESS | tESS J> I --H -< z SETS | ITY DESIGNATION COMPRESSIVE STRENGTH 10NAL CHARACTERISTJCS CLASSIFICATION S \. TIES \. X X X X TERZAGHI X X X LAUFFER-PACHER X X DEERE X X X X X X X X RSR X X X X X X X X X X X X RMR X X X X X X X X X Q X X X X X X X X MODIFIED Q KIRSTEN X X X LOUIS X X X X X X X X FRANKLIN X X X X X COATES AND PARSONS X X X X X BULICHEV X X X X X X ' X <x X X X X X LAUBSCHER X X X X X X X X X X X X X K t N U U K i K l j * X McKAHON 0 X X X X X X X X X MATHEWS H* X X X X X NICHOLAS ^ X X MULLER Table 3.4: Participating Mining Operation '' No. PROD. RATE(TPO) MINIM OEPTH(B) ORE TYPE ORE DlP(deq) MINING METHOD 1 6500 1220 Ni Sulph. 65-70 36'/ OS,457. CiF, 197. VCf 2 <1000 960 Au-Aq 90 too* OS 3 4200 520 Pb-Zn-Cu 80 1007. OS 4 10500 910 Pb-Zn-Cu-Aq 65-75 1007. CiF 5 800 460 Au 75-80 907. OS. 107. SHR 6 2000 610 Cu-Au 55-85 541 OS,241 SHR 7 1400 850 HS 40 1007. OS 8 2600 270 Pb-Zn Sulp 20 1001 OS 9 10000 610 Fe-Pb-Zn-Aq 30-35 1007. OS C&F: 10 11800 960 Cu-Pb-Zn 75-85 977 OS .3'/ SC OS: 11 1425 240 Breccia 15-30 607 CiF,401 OS VCR: 12 <1000 400 Chert.Sulf 65-90 80* VCR.207 PR SHR: 13 1400 240 HS 55 1007. CiF SC: 14 1400 1070 ' HS 65 507. SC, 307 OS R&P: 15 UOOO 330 HS 80-85 1007. VCR PR: 16 <1000 1100 MS 42 90X CiF,107 OS 7.: 17 <1000 1000 HS 70 807. VCR,207 CiF 18 12800 910 OTZ-Conq 19 1007. RiP 19 4000 1250 QTZ-Conq 9-15 1007. RiP 20 5000 850 QTZ-Conq 20 100Z RIP 21 3000 530 QTZ-Conq 20 1007. RiP 22 3350 300 Niobium 90 100X OS Legend Cut and F i l l Open Stope V e r t i c a l Crater Retreat Shrinkage Sub-Level Cave Room and P i l l a r P i l l a r Recovery Percent of Total Production Table 3 . 5 : Open Stope Mining Operators (Stope) No. MINING OEPTH(n) RHR(X) UIDTH(n) SPAN/HEIGHT(«) KYD.RAD . (n) OIL. a: 1 670 66 4.5-18 12/46 5 50 ? 2 137-960 63 9 61/91 18 15 3 520 68 34 30/122 12 30 ? 5a 250 80 8 13/45 5 5 5b 250 63 5 25/45 8 15 6* 160 36 2 15/61 6 32 6b 251 45 2 18/79 1 25 6c 343 45 2 IB/73 7 30 6d 610 42 2 18/62 7 50 7a 823 68 46 46/61 13 10 7b 823 68 30 23/61 8 17 8a 120 60 10 101/25 10 0 Bb 149 60 15 .101/60 19 0 9a 107 70 61 61/41 12 12 9b 366 70 21 168/55 8 12 tOa 427 57 18 46/91 15 10 10b 914 57 15 30/61 10 5 11 230 57 15 40/20 7 5 17 277 51 10 16/28 5 26 14 396 59 24 30/122 12 NA 15a 200 48 10 80/45 14 30 15b 300 60 10 80/45 14 NA 17a 640 25 10 37/43 10 50 17b(sh) 366 25 10 107/37 14 .30 17c(sh) •914 25 10 91/37 13 30 22 243 52 24 46/91 15 4 Legend Sh: Open Stope Shrink BMR: Bock Mass Rating of FfancHng Ball HYJD RAD: f (Span.Height) ON Table 3.6: Open Stope Mining Operators ( P i l l a r ) Ho. MIHING DEPTH(») RHR(X) LD(N) LD/MO Lo(n) Lp/Lo 1 670 6! NA NA NA 12 NA 2 137-960 63 5 4 1 .3 61 . 4 3 520 67 27 34 . 8 30 . 9 5a 250 80 25 8 3 . 2 13 1 . 9 5b 250 80 25 5 5 . 0 25 1 6a 160 29 4 2 2 . 0 15 . 3 6b 251 34 6 2 3 . 0 18 . 3 6c 343 37 5 2 2 . 5 18 . 3 6d 610 37 5 2 2 . 5 IB . 3 7a 823 68 15 46 . 3 46 . 3 7b 823 68 15 30 . 5 23 . 7 8a 120 58 100 10 10. 101 1. 8b 149 69 100 15 6 . 7 100 1. 9a 107 69 122 61 2 . 61 2 . 9b 366 69 168 18 9 . 3 168 1. 10a 427 100 46 24 1 .8 46 1. 10b 914 too NA NA NA 30 NA 11 230 90 40 10 4 . 40 1. 12 277 80 4 3 1 .3 16 . 3 14 396 89 6 34 . 2 30 . 2 15a 200 61 80 10 8 . 80 1. 15b 300 61 80 10 8 . 80 1. 17a 640 87 21 11 1 . 9 37 . 6 I7b(sh ) 366 87 107 11 9 . 8 107 1. 17c(sh ) +914 87 91 11 B . 3 91 1. 22 243 52 46 24 1 . 9 46 1. Legend RMR Rock Mass Rating o f P i l l a r Lp Length of P i l l a r Wp Width of P i l l a r Lo Length of Opening NA Not Applicable - Isolated Stope 6 4 To compensate f o r o r i g i n a l assumptions; a f a c t o r of safety o f s i x i s generally employed. (Wright,1980) F i g u r e 3.1: Beam T h e o r y F i g u r e 3.2: f o u s s o i r A r c h The beam i s assumed to be supported by re su l t an t a rch ing a c t i o n . Note shear s t resses ( i n t e r s l i c e forces ) must be overcome f o r a s i n g l e block to f a l l out. 3: N u m e r i c a l S o l u t i o n K . T e n s i l e stress* i n the back i s an i n d i c a t o r that the r e -g i on i s i n a s ta te o f r e l a x a -t i o n and consequent ly^struc-t u r a l b locks may be re leased. I f the back t i s a homogeneous beam.the t e n s i l e strength of the beam must be exceeded fo r f a i l u r e to occur. . High compression i n the roof, coupled with low compressive f o r c e s normal to the roof may r e s u l t i n buck l ing f a i l u r e . Th i s i s p a r t i c u l a r l y true i f s t ruc tu re s p a r a l l e l i n g the roo f are present. . F a i l u r e when the shear strength o f the rock i s exceeded. 65 IOOO.0 IOO.O ! IO.O S IO 15 ZO 25 Shape Factor (S) - Ar&o/Ptej-ime+er fa) F i g u r e 3 . 4 : Mathews Method of Stope Design (Mathews et a l , 1981) F i g u r e . 3 . 5 : H a n g i n g W a l l and F o o t w a l l Beam D e f l e c t i o n 66 F i g u r e 3.6: S t r e s s T r a j e c t o r i e s - 320m L e v e l , Plan View klHlfcl l a . i t c i i I I I I I I I I / II' I i \ I I \ \ \ I I V I I \ I I I I \ I t I I M t I i M i l l p i l l a r - 70 GPa I I I ' I I I I I I I I I I I I I i l l ! i i I I / I,' ' FiiiAmi I \ \ \ \ I U I I ! I I I I I I I I I I t I I I t p i l l a r 7 GPa ftiMIS I K a j t C l M M I -r.uc. M i l . . I • I I I / / ' I I.I,/ / I II: • i t i i \ • i i i i \ \ » » i i \ i i * \ > i i i i I,I i 1 1 . , ! . ! * i \ M 1 1 ' / I I p i l l a T • 700 MPa E , ' - 70 13>a p i l l a r E ... Removed p i l l a r Load i s shed to adjacent areas as p i l l a r i s wrecked. This i s simu-lated by reducing the p i l l a r modulus. Figure 3 . 8 : P l a n View of Two Adjacent Stopes MINE PRODUCTION SIZE (TPD) D A T A B A S E - 2 2 M I N E S > B O O O T P O (ta.ox) S 0 0 0 - 8 0 0 0 T P O ( 3 . O K ) 3 0 0 O - 5 0 0 O T P D ( 1 8 . 0 X ) U N D E R tOOOTPO ( 2 7 . 0 * ) 1 0 0 0 - 3 0 0 0 T P O ( 3 2 . 0 K ) F i g u r e 3.9: D i s t r i b u t i o n o f Mine P r o d u c t i o n S i MINING METHOD - DATA B A S E (22 MINES) ze O T H E R ( 3 . 0 * ) C U T * F I L L ( 1 9 . 0 * ) O P E N S T O P E (50.0*) R O O M * P I L L A R C3Z.0K) F i g u r e 3.10: D i s t r i b u t i o n o f M i n i n g Method MINING DEPTH (METERS) DATA B A S E - 22 MINES >1200m (9.0*) 97. OS, 187, C 8c F, 14% R St 187. Ot 900m-I 200m (23.OK) 357. OS, 697. C & F, 457. R St P, 537. Oth 600m-900m (18.OK) 317. OS, 07. C St F, 187. R sTp <3O0m (I4.0X) 87. OS, 137. C 7. F, 127. R St P, ^ 07. Oth F i g u r e 3.11: D i s t r i b u o f M i n i n g Depth 300m-600m (36.OK) 177. OS, 07. C St F, 117. R St P, 117. Oth too so R O C K S T R E N G T H P A R A M E T E R S DATA B A S E - 22MINES AA A/< YAA AA % 'AA % AA> A/> A//X AAA YAA % m VA /A /A VAA VA YA % YAA YA VArrm YA YAA m VA VAA VA VAA w M Y4 Y/A Y/A YA YAA YAA YAA AA m V/A VAA VAA YAA VAA VA ao 70 6 0 40 S O 2 0 10 F i g u r e 3.12: Rock S t r e n g t h P a r a m e t e r s 1 0 0 so B O 7 0 S T R E S S I N V E S T I G A T I O N S DATA B A S E - 22MINES '////////\ V//////A ////// // y///////A mw. y//////A WW/ Y//////A 'WM '////////, A/AAAAA Y///////A, VAAAAAA '///////A AWAAA VA//////, WAAA so 40 IN-SITU PHOTO C O M . M O D . F i g u r e 3.13: S t r e s s I n v e s t i g a t i o n z o p o s too • so • eo 7 0 6 0 so 4 0 so 2 0 10 R O C K M A S S C L A S S I F I C A T I O N D A T A B A S E - 22MJNES V/AAA AAA, AAA VAAAA AAA 77777X AAA AAA YA/AA /AAA AAA AAA WA WA AAA WA AAA YW AAA AAAA WA AAA AA/A RQD VAA/A Q A/A RMR V77J7y\ L A U B 'AAA S T . M A P F i g u r e 3.14: Rock Mass I n v e s t i g a t i o n D E S I G N M E T H O D O L O G Y D A T A B A S E - 2 2 M I N E S P R A C . Ic C O M P . ( 1 1 . O K ) P R A C . ic EMPIR. ( I t . O K ) P R A C T I C A L ONLY ( 3 4 . 0 K ) P R A C . * EMPIR. 4c C O M P . ( 4 4 . 0 * ) F i g u r e 3.15: Methods o f D e s i g n DILUTION - OPEN STOPING METHODS DATA BASE - 1SMINES >3SM DILUTION (21.OH) <tOK DILUTION (32.OK) 2 0 - S 5 K DILUTION ( 2 8 . 0 * ) 1 0 - 1 8 * DILUTION ( 2 1 . 0 * ) F i g u r e 3.16: St o p e D i l u t i o n too -j eo -ao -u o 70 -5 | eo -so -40 -6 30 -0. 20 -10 -0 -ROCK MASS RATING - OPEN STOPES DATA OASE - 23STOPES. ( 1 3 MINES) 1 0 0 - 1 1 80^-91 6 0 - 4 1 4 0 - 2 1 F i g u r e 3.17: Rock Mass R a t i n g OPEN STOPING 31 MINES SEVERE MOOER ATE LITTLE OR NONE z o _ l -J or o — LJ Q cc AINT. ,LLS H. UP! NST. NST. EV. NCE LI TY 5 I -<i u. u. o 'PT. CC < LJ MIC IDE ABI u. < - j Ur in DJ VE CC O CC t - UJ Z> < Q CC o CL m in in z o LJ 2 o < CC LJ < a co < 5 F i g u r e 3.18: Ground C o n t r o l P r o b l e m s i n Open S t o p l n g O p e r a t i o n s O P E N S T O P E D I M E N S I O N S -DATA BASE - 23 STOPES (13 MINES) S P A N S O P E N S T O P E D I M E N S I O N S -DATA BASE - 23 STOPES (13 MINES) W I D T H S >60 m (48.0X) Figure 3.19: Open Stope Dimensions OPEN STOPE PILLAR DIMENSIONS (Lp /Wp) DATA BASE « 2 4 STOPES. 1 3 UINES <t 1 - 2 . 5 2 . 5 - 4 . 5 4 . 5 - 6 . 5 >«.5 PILLAR LENOTH /PILLAR WIDTH (Lp/Wp) Figure 19bi |? 3 q b OPEN STOPE PILU\R DIMENSIONS ( L p / L o ) DATA BASE - 2 4 STOPES. 1 5 MINES PILLAR LENOTH /STOPE LENOTH (Lp/Lo) F i g u r e 3.21: P i l l a r D i m e n s i o n s F I L L U T I L I Z A T I O N - O P E N S T O P E S DATA B A S E - 1 5 MINES F i g u r e 3.20: F i l l O t i l i z a t i o n 73 CHAPTER FOUR STRESS 4.1 I n t r o d u c t i o n T h i s t h e s i s a t t e m p t s to d e l i n e a t e a l l p a r a m e t e r s t h a t c o n t r i b u t e towards w a l l s l o u g h . B r a d y and Brown ( 1 9 8 5 ) s t a t e t h a t upon " i d e n t i f y i n g the f e a s i b l e b l o c k c o l l a p s e modes a s s o c i a t e d w i t h j o i n t a t t i t u d e s and e x c a v a t i o n s u r f a c e g e o m e t r y , i t i s n e c e s s a r y to d e t e r m i n e the p o t e n t i a l f o r b l o c k d i s p l a c e m e n t under the a m b i e n t c o n d i t i o n s w h i c h e x i s t i n the p o s t - e x c a v a t i o n s t a t e of the o p e n i n g p e r i p h e r y " . The c o n t r i b u t i n g s t r e s s f a c t o r s t h a t would a f f e c t the s t a b i l i t y of an i n d i v i d u a l b l o c k a r e g r a v i t a t i o n a l , h y d r o s t a t i c and c o n f i n i n g s t r e s s e s . T h i s c h a p t e r w i l l show t h a t the h a n g i n g w a l l and f o o t w a l l of s t o p e s a t R u t t a n a r e i n a s t a t e of r e l a x a t i o n . T h i s d i c t a t e s t h a t a l l s t r e s s e s ( o t h e r t h an g r a v i t a t i o n a l ) a c t i n g on a p a r t i c u l a r w a l l segment a r e l e s s t h a n or e q u a l to z e r o . C o n s e q u e n t l y t h a t p a r t i c u l a r segment i s not c o n f i n e d and c o u p l e d w i t h a j o i n t e d m a t e r i a l would r e s u l t i n the b l o c k to s l i p out u n d e r i t s ' "own w e i g h t " . T h i s c h a p t e r w i l l s t u d y the v a l i d i t y of the a s s u m p t i o n t h a t the h a n g i n g w a l l and f o o t w a l l of the i n d i v i d u a l s t o p e s a r e i n a s t a t e of r e l a x a t i o n . 7 4 4 . 2 I n - S i t u S t r e s s e s a t R u t t a n P r i o r to u n d e r s t a n d i n g the e f f e c t of s t r e s s e s on o p e n i n g s at R u t t a n , i t i s i m p o r t a n t to d e t e r m i n e the magn i t u d e and o r i e n t a t i o n of the i n - s i t u r o c k s t r e s s e s i n f l u e n c i n g the R u t t a n o p e r a t i o n . T h e s e s t r e s s e s a r e r e l a t e d to the w e i g h t of the o v e r l y i n g s t r a t a and the g e o l o g i c a l h i s t o r y of the r o c k mass. " D o o r s t o p p e r - p h o t o e l a s t i c " t e c h n i q u e s have been employed i n the p a s t a t R u t t a n ( S m i t h , 1 9 7 7 ) . These r e s u l t s , w h i l e s i m i l a r i n o r i e n t a t i o n to the most r e c e n t measurements done a t R u t t a n , were c o n c l u d e d to be anomolous s i n c e t h e y were r e c o r d e d i n t oo c l o s e p r o x i m i t y to the t u n n e l f a c e (0.2 x d r i f t d i a m e t e r ) . T h i s s e c t i o n d e s c r i b e s a m e t h o d i c a l a p p r o a c h to the e s t i m a t i o n of the o r i e n t a t i o n and the magn i t u d e of the i n - s i t u s t r e s s e s t h a t e x i s t a t R u t t a n . I n i t i a l e s t i m a t e s were made based upon: - s t r u c t u r a l i n t e r p r e t a t i o n - v i r g i n s t r e s s measurements c o n d u c t e d i n o t h e r a r e a s ( w o r l d wide, r e g i o n a l ) The v e r i f i c a t i o n of the p r e v a i l i n g s t r e s s r egime was made by c o n d u c t i n g CSIRO h o l l o w i n c l u s i o n o v e r c o r i n g measurements ( W o r o t n i c k i . and W a l t o n , 1976). The c u r r e n t c o s t f o r v i r g i n s t r e s s d e t e r m i n a t i o n i s about $7000 per measurement and the d i f f i c u l t y e n c o u n t e r e d i n a t t a i n i n g a good r e a d i n g i s h i g h . T h r e e o v e r c o r e 75 t e s t s were performed at the 660m l e v e l i n order to evaluate the i n - s i t u s t r e s s magnitudes and o r i e n t a t i o n s . The p r e v a i l i n g s t r e s s regime can be summarized as f o l l o w s : - V e r t i c a l s t r e s s = <£v (MPa) = 0.027 x depth (m) -Major p r i n c i p a l s t r e s s = 4l = 2.5 Aw ( 340°/ -20°) -Intermediate p r i n c i p a l s t r e s s =42 = 1 . 2 ^ v (070°/0°) -Minor p r i n c i p a l s t r e s s = 43 = 0.8«dv (160°/-70°) The above are expressed as azimuth from true north/plunge with i n d i v i d u a l t e s t s performed 660m below s u r f a c e . A d e t a i l e d a n a l y s i s of the f i n d i n g s reported i n t h i s s e c t i o n can be found i n P a k a l n i s and M i l l e r (i983) 4.2.1 S t r u c t u r a l I n t e r p r e t a t i o n The Ruttan d e p o s i t , as s t a t e d p r e v i o u s l y (Chapter 2), i s l o c a t e d i n a greenstone b e l t which i s p o s t u l a t e d to be an i s l a n d a r c . The i s l a n d a r c , i s a product of c r u s t a l movements, whereby a p l a t e of l i t h o s p h e r e i s slowly plunging downward i n t o the mantle. This t e t o n i c a c t i v i t y i s thought to have r e s u l t e d i n the i n c l i n a t i o n of the Ruttan orebody as shown i n Figure 2.6, It i s p o s t u l a t e d that the C h u r c h i l l province subducted underneath the Superior p r o v i n c e and consequently induced the i n - s i t u f o r c e s i n d i c a t e d In F i g u r e 2.3. There i s great evidence to suggest that s t r e s s e s i n rock are r e l a t e d to g e o l o g i c s t r u c t u r e ( Parker , 197 3 ) . Figure 4.1 shows the f r a c t u r e p a t t e r n that may r e s u l t In the crushing of a 7 6 r o c k c y l i n d e r . The o r i e n t a t i o n of the f r a c t u r e p a t t e r n i s u n i q u e to the a p p l i e d s t r e s s c o n d i t i o n . I t must be e m p h a s i z e d t h a t o n l y the most " r e c e n t l y f o r m e d " s t r u c t u r e s must be a n a l y z e d i n o r d e r to a i d i n e s t i m a t i n g the o r i e n t a t i o n of the e x i s t i n g s t r e s s f i e l d . L o c a l g e o l o g i c a l mapping o u t l i n e d q u a r t z v e i n i n g and dykes h a v i n g a t r e n d of a p p r o x i m a t e l y N20°W. T h i s c o r r e s p o n d s to a major r e g i o n a l f e a t u r e , the " M a c k e n z i e Dyke Swarm" ( F i g u r e 2 . 3 ) , which i s f o u n d t h r o u g h o u t N o r t h e r n M a n i t o b a . These s t r u c t u r e s a r e t e n s i l e f e a t u r e s w hich p a r a l l e l the major p r i n c i p a l s t r e s s d i r e c t i o n , F i g u r e 2.3. In a d d i t i o n , l o c a l f o l d i n g of q u a r t z v e i n s and the e v i d e n c e of b o u d i n a g e a l l p r e d i c t a m a j o r s t r e s s d i r e c t i o n , t r e n d i n g a p p r o x i m a t e l y N20°W. F o l i a t i o n p a r a l l e l i n g the d e p o s i t i s the most dominant s t r u c t u r e a t the m ine. I t Is t h o u g h t t o have formed d u r i n g the f o r m a t i o n of the d e p o s i t , whereby due to v e r t i c a l b u r i a l f o r c e s , a p r e f e r r e d o r i e n t a t i o n of p l a t e l e t s p a r a l l e l to the d e p o s i t w e r e . e s t a b l i s h e d , F i g u r e . 4.2. The above g e o l o g i c a l e n v i r o n m e n t i n f l u e n c i n g the R u t t a n orebody s u g g e s t s t h a t the e x i s t i n g s t r e s s o r i e n t a t i o n may be t r e n d i n g N20°W t o S 20°E. 4.2.2 P r e v i o u s Measurements A s t u d y of a r e a s t h r o u g h o u t v i r g i n s t r e s s measurements the w o r l d w i l l g r e a t l y , aid. c o n d u c t e d i n o t h e r i n the 77 d e t e r m i n a t i o n of the i n - s i t u s t r e s s a t the p r o p o s e d l o c a t i o n . F i g u r e 4.3 i s a p l o t of v e r t i c a l s t r e s s w i t h d e p t h as c o m p i l e d by Hoek and Brown ( 1 9 8 0 ) . F i g u r e 4.4 i s a p l o t of h o r i z o n t a l to v e r t i c a l s t r e s s as a f u n c t i o n of d e p t h , H e r g e t ( 1 9 8 0 ) , and i s b a s e d on numerous measurements c o n d u c t e d w i t h i n the C a n a d i a n S h i e l d . V i r g i n s t r e s s measurements at R u t t a n were c o n f i n e d to the 661m l e v e l below s u r f a c e . T h i s would i m p l y the f o l l o w i n g e x i s t i n g s t r e s s m a g n i t u d e s : V e r t i c a l S t r e s s = 18 Mpa H o r i z o n t a l S t r e s s = 27 Mpa ( r e f e r F i g u r e s 4.3,4.4) I n - s i t u s t r e s s measurements i n the v i c i n i t y of the R u t t a n o rebody have been p e r f o r m e d a t the Thompson Mine (Moss and N i e m i , 1 9 8 5 ) , Thompson and the M c L e l l a n Mine ( R o t z i e n and M i l l e r , 1 9 8 5 ) , Lynn Lake ( F i g u r e 2 . 3 ) . The r e s u l t s i n d i c a t e t h a t the m a g n i t u d e s of s t r e s s can be a p p r o x i m a t e d by F i g u r e s 4.3,4.4. The o r i e n t a t i o n s f o r t h e s e two o p e r a t i o n s can be summarized as f o l l o w s : - major p r i n c i p a l s t r e s s t r e n d s N70°W, p l u n g e s 10° - i n t e r m e d i a t e p r i n c i p a l s t r e s s t r e n d s N 3 0 ° E , p l u n g e s 10 - minor p r i n c i p a l s t r e s s i s n e a r v e r t i c a l 4.2.3 V i r g i n S t r e s s Measurements To d e t e r m i n e the s t r e s s a t a p o i n t i n the r o c k . m a s s , " i t 78 i s n e c e s s a r y to change the s t r e s s from i t s unknown v a l u e ( i n - s i t u ) to z e r o , and c o n s e q u e n t l y measure the a s s o c i a t e d change i n s t r a i n . T h i s change i s i n t r o d u c e d by an o v e r c o r i n g o p e r a t i o n w h i c h c o m p l e t e l y r e l i e v e s the s t r e s s e s a c t i n g on a p i e c e of c o r e . S i n c e the s t a t e of s t r e s s a t any p o i n t i n a body can be c o m p l e t e l y d e f i n e d by i t s t h r e e n o r m a l s t r e s s e s and t h r e e a s s o c i a t e d s h e a r components, i t i s n e c e s s a r y to c a r r y out s i x i n d e p e n d e n t measurements i n the r o c k . The e l a s t i c c o n s t a n t s of the r o c k must a l s o be d e t e r m i n e d , s i n c e s t r a i n i s r e l a t e d to s t r e s s by a d e f o r m a t i o n m o d u l u s . The CSIRO h o l l o w i n c l u s i o n c e l l was employed. The CSIRO c e l l c o n t a i n s n i n e gauges; two a x i a l l y , t h r e e c i r c u m f e r e n c i a l l y and f o u r a n g u l a r gauges o r i e n t e d r e l a t i v e to the b o r e h o l e a x i s . I t i s i n s t a l l e d i n - s i t u and s u b s e q u e n t l y o v e r c o r e d w i t h c o r r e s p o n d i n g s t r a i n s r e c o r d e d . T h e o r y and i n s t a l l a t i o n p r o c e d u r e f o r the CSIRO c e l l can be f o u n d i n a paper by W o r o t n i c k i and W a l t o n ( 1 9 7 6 ) . Three measurements were c a r r i e d out i n a s i n g l e b o r e h o l e at 660m below s u r f a c e , F i g u r e 4.5. The f i r s t t e s t was c o n d u c t e d at a b o r e h o l e d e p t h of 6.7m, w i t h s u b s e q u e n t t e s t s a t 7.1m and 7.4m. T h i s was r e q u i r e d i n o r d e r to e n s u r e t h a t the t e s t s were p e r f o r m e d away from any s t r e s s i n f l u e n c e s , (two t u n n e l d i a m e t e r s ) . The t e s t h o l e was i n c l i n e d at +23 from h o r i z o n t a l and d r i l l e d p e r p e n d i c u l a r to the t r e n d of the o r e b o d y . A c o n t i n u o u s r e c o r d i n g u n i t was employed, c a p a b l e of s c a n n i n g each s t r a i n gauge e v e r y 20 s e c o n d s . S t a n d a r d HX b i t s were 79 employed w h i c h p r o d u c e d an 86.7 mm d i a m e t e r o v e r c o r e . 4.2.3.1 D i s c u s s i o n of R e s u l t s F i g u r e 4.6 summarizes the r e s u l t a n t m a g n i t u d e s and d i r e c t i o n s of the p r i n c i p a l s t r e s s e s as d e r i v e d f o r each CSIRO t e s t . Note t h a t f o r c e r t a i n gauges two s t r a i n v a l u e s were e x t r a p o l a t e d s i n c e a s i n g l e v a l u e c o u l d not be d e l i n e a t e d . A modulus of d e f o r m a t i o n of 70 GPa and P o i s s o n ' s r a t i o of 0.18 were empl o y e d . F i g u r e 4.7 shows a p l o t of o v e r c o r e d d i s t a n c e v e r s u s r e l e a s e d s t r a i n f o r CSIRO T e s t #2. P a r t i a l d e b o n d i n g o c c u r r e d i n CSIRO #1 and #3. T h i s r e s u l t e d i n a c o n s i d e r a b l e v a r i a t i o n In the measured s t r e s s m a g n i t u d e s . One method f o r c h e c k i n g the v a l i d i t y of the r e s u l t s i s to see how the d e r i v e d v e r t i c a l s t r e s s d e v i a t e s f r o m the o v e r b u r d e n s t r e s s c a u s e d by the w e i g h t of the o v e r l y i n g r o c k . CSIRO v a l u e s a r e a l s o compared to o t h e r measurements o b t a i n e d from the l i t e r a t u r e . The s t r e s s m a g n i t u d e s , as p r e d i c t e d from the l i t e r a t u r e , would be as f o l l o w s : v = 18 MPa i h = 27 MPa ^ h M v = 1 . 5 S t r e s s measurements c o n d u c t e d a t R u t t a n i n d i c a t e d a «4h/<£v r a t i o r a n g i n g from 1.3 to 1 . 9 , w h i c h i s i n agreement w i t h v a l u e s o b t a i n e d In o t h e r l o c a l i t i e s , F i g u r e 4.4. F i g u r e 4.6 a l s o shows 80 t h a t the n o r m a l i z e d p r i n c i p a l s t r e s s e s Al/^v, Al /Aw, A3 /Av f o r a l l t h r e e CSIRO measurements were i n g e n e r a l a greement: ^ l M v r a t i o v a r i e s 2.1 - 3.1 £2/6v r a t i o v a r i e s .9 - 1.2 i 3 M v r a t i o v a r i e s . 7 - .8 The above shows t h a t even t h o u g h the s t r e s s v a l u e s f o r CSIRO #1 and CSIRO #3 were e x c e s s i v e l y e xtreme and v a r i a b l e , the n o r m a l i z e d v a l u e s were i n g e n e r a l a g r e e m e n t . These extremes a r e most l i k e l y due t o s t r e s s c o n c e n t r a t i o n s t h a t r e s u l t from a i r b u b b l e s i n the v i c i n i t y of the gauge. F i g u r e 4.8 i s a p l o t of s t r e s s d i r e c t i o n s r e c o r d e d t h r o u g h o u t the C a n a d i a n S h i e l d . In a d d i t i o n , the measured p r i n c i p a l s t r e s s o r i e n t a t i o n s a t R u t t a n a r e a l s o i n d i c a t e d . The measured s t r e s s d i r e c t i o n s and m a g n i t u d e s a r e i n good agreement w i t h : - t h e o r e b o d y geometry - g e o l o g i c a l e n v i r o n m e n t - o t h e r measurements c o n d u c t e d t h r o u g h o u t the C a n a d i a n S h i e l d 4 . 2 . 4 O b s e r v a t i o n s I t i s g e n e r a l l y c o n c l u d e d t h a t s t r e s s m a g n i t u d e s and d i r e c t i o n s a r e as shown i n F i g u r e 4.8. The CSIRO t e c h n i q u e 81 a l l o w s one to r e c o r d the e n t i r e s t r a i n r e l i e f h i s t o r y as o v e r c o r i n g commences. T h i s p r o v e d to be i n v a l u a b l e i n f o r m a t i o n i n u t i l i z i n g the r e s u l t s from T e s t #1 and T e s t #3. The r e s u l t s w i l l be employed i n m o d e l l i n g of the i n d u c e d s t r e s s b e h a v i o u r s u r r o u n d i n g o p e n i n g s a t R u t t a n . F our s u c c e s s f u l CSIRO s t r e s s measurements have been r e c e n t l y c o n d u c t e d on the 620 and 800m l e v e l I n d i c a t i n g s i m i l a r r e s u l t s to t h o s e d e s c r i b e d i n F i g u r e 4.4. The r e c e n t measurements a r e p a r t of a b r o a d e r program of r e s e a r c h s p o n s o r e d by CANMET and S h e r r i t t Gordon Mines on the development of s t o p e and p i l l a r d e s i g n g u i d e l i n e s . 82 4.3 S t r e s s C o n f i g u r a t i o n The s t r e s s m a g n i t u d e s and o r i e n t a t i o n s , shown i n F i g u r e 4.8, w i l l be employed i n o r d e r to d e t e r m i n e the s t a t e of i n d u c e d s t r e s s t h a t e x i s t s a t the w a l l c o n t a c t s . P a r a m e t r i c s t u d i e s were p e r f o r m e d on the g e o m e t r i c shapes shown i n F i g u r e 2.17. The v a r i a n c e of a x i a l t o d i a m e t r i c a l ( s p a n / w i d t h ) d i m e n s i o n s were e v a l u a t e d i n terms of the e f f e c t on the s t a t e of i n d u c e d s t r e s s . The h y p o t h e s i s i s based upon a " r e l a x e d " s t a t e of s t r e s s e x i s t i n g i n the w a l l c o n t a c t s (HW/FW). C o n s e q u e n t l y , the a n a l y s i s i s more c o n c e r n e d w i t h the q u a l i t a t i v e c o m p a r i s o n s t h a n w i t h a b s o l u t e q u a n t i t a t i v e r e s u l t s . The s t r e s s i n d u c e d r e g i m e i s e v a l u a t e d based on the a s s u m p t i o n of two d i m e n s i o n a l p l a n e s t r a i n . I t i s t h e n v e r i f i e d i n the q u a l i t a t i v e s e n s e by a t h r e e d i m e n s i o n a l boundary e l e m e n t n u m e r i c a l c o d e . 4.3.1 N u m e r i c a l Code A two d i m e n s i o n a l b oundary e l e m e n t program was employed. The s o l u t i o n i s used to i d e n t i f y and compare the s t a t e of s t r e s s r e s u l t i n g from d i f f e r e n t s t o p e c o n f i g u r a t i o n s . " B i t e m " , a computer program, o b t a i n e d from the CSIRO (Commonwealth S c i e n t i f i c and I n d u s t r i a l R e s e a r c h O r g a n i z a t i o n ) , i s c a p a b l e of two d i m e n s i o n a l b oundary e l e m e n t m o d e l l i n g of up to f i v e p i e c e w i s e homogeneous r e g i o n s . T h i s program was m o d i f i e d to run 83 on the U .B .C Amhdah l c o m p u t e r s y s t e m . F u r t h e r m o d i f i c a t i o n s were i n e n l a r g i n g i t s m o d e l l i n g c a p a b i l i t i e s and i n d e v e l o p i n g a p o s t - p r o c e s s i n g p r o g r a m t h a t wou ld g r a p h i c a l l y d i s p l a y : - P r i n c i p a l S t r e s s C o n t o u r s - Maximum S h e a r S t r e s s C o n t o u r s - S t r e s s T r a j e c t o r i e s - D i s p l a c e m e n t s In a d d i t i o n , the f o l l o w i n g f a i l u r e c r i t e r i a were i n c o r p o r a t e d i n t o the p r o g r a m : - Mohr Coulomb - No T e n s i o n - Hoek Rock Mass F a i l u r e C r i t e r i o n . The f a i l u r e c r i t e r i a were i n c o r p o r a t e d to i d e n t i f y p o s s i b l e f a i l u r e z o n e s . T h i s , h o w e v e r , does n o t fo rm an i n t e g r a l p a r t to the s o l u t i o n of the s t a t e d h y p o t h e s i s . The r e a d e r i s r e f e r r e d to a r e p o r t p r o d u c e d by the a u t h o r " B i t e m O p e r a t i n g M a n u a l " and " P l o t - B i t e " f o r f u r t h e r d e t a i l s . In a d d i t i o n ,"3DBELM", a t h r e e d i m e n s i o n a l b o u n d a r y e l e m e n t p rog ram was o b t a i n e d t h r o u g h CSIRO . The p rog ram mode l s the b o u n d a r y by p i e c e w i s e f l a t t r i a n g l e s o v e r w h i c h the bounda ry d a t a v a r i e s l i n e a r l y . M o d i f i c a t i o n s to the p rog ram a r e as f o l l o w s : - M o d i f i c a t i o n of code to e n a b l e i t to r u n on the U . B . C . 84 Amhdahl system - I n c r e a s e i n p r o b l e m s i z e i e . number of e l e m e n t s and nodes a l l o w e d T h i s program can model m u l t i p l e o p e n i n g s , however i n p r a c t i c e , the a s s o c i a t e d c o s t s l i m i t i t s a p p l i c a t i o n . U n l i k e B i t e m , i t can o n l y model a s i n g l e p i e c e w i s e homogeneous r e g i o n . T a b l e 4.1 summarizes the program s p e c i f i c a t i o n s f o r " B i t e m " and the "3DBelem" programs r e s p e c t i v e l y . 4.3.2 P a r a m e t r i c Study The i n - s i t u s t r e s s e s a t R u t t a n as shown In F i g u r e 4.8 were employed i n m o d e l l i n g t y p i c a l s t o p e g e o m e t r i e s . F i g u r e 4.9 shows t h a t f o r o p e n i n g g e o m e t r i e s where the i n - s i t u s t r e s s e s a r e g r e a t e s t , p e r p e n d i c u l a r t o the l o n g e s t d i m e n s i o n r e s u l t i n the immediate s i d e w a l l s t r e s s e s to be t e n s i l e . The "k" v a l u e , as d e f i n e d i n F i g u r e 4.9, would be g r e a t e s t i n the v e r t i c a l p l a n e of the o r e b o d y and l e a s t i n the h o r i z o n t a l p l a n e , F i g u r e 4.10. T h i s would y i e l d l o w e r t e n s i l e s t r e s s e s i n the h o r i z o n t a l p l a n e of the o r e b o d y . Fo r p u r p o s e s of c o n s e r v a t i s m , the n u m e r i c a l a n a l y s i s was c o n d u c t e d on the h o r i z o n t a l p l a n e o n l y . The magnitude and e x t e n t of the t e n s i l e zone would o n l y be m a g n i f i e d i n the v e r t i c a l p l a n e of the o r e b o d y . P a r a m e t r i c s t u d i e s were c o n d u c t e d whereby the s t o p e s p a n / w i d t h r a t i o s , as d e f i n e d i n F i g u r e 4.10, were a l t e r e d under a c o n s t a n t s t r e s s r e g i m e . I t was shown t h a t f o r the i s o l a t e d s t o p e c a s e , f o r 85 s t o p e s h a v i n g a s p a n / w i d t h r a t i o e x c e e d i n g 0.66:1, the h a n g i n g w a l l and f o o t w a l l commence g o i n g i n t o t e n s i o n , F i g u r e 4.11. The s t r e s s c o n f i g u r a t i o n showing minor p r i n c i p a l s t r e s s e s ( d ashed) and major p r i n c i p a l s t r e s s c o n t o u r s ( s o l i d ) f o r the i s o l a t e d c a s e s a n a l y z e d i s shown i n F i g u r e 4.12. The e x t e n t of the t e n s i l e i n d u c e d zone i s shown by F i g u r e 4.13 as a f u n c t i o n of the s t o p e g e o m e t r y . T y p i c a l s t o p e g e o m e t r i e s a t R u t t a n a p p r o a c h the 2:1 and 4:1 s p a n / w i d t h r a t i o s . T h i s would e n s u r e t h a t the ore c o n t a c t s ( s p a n ) w i l l a l w a y s be i n a s t a t e of r e l a x a t i o n . A t y p i c a l s t o p e span to w i d t h of 4:1 would i n d i c a t e t h a t the e x t e n t of the t e n s i l e zone would c o r r e s p o n d to a w a l l s l o u g h e x t e n d i n g 0.55 s t o p e w i d t h s beyond t h e r e s e r v e w a l l c o n t a c t . The maximum s t o p e d i l u t i o n r e c o r d e d a t R u t t a n i s a p p r o x i m a t e l y 20% w h i c h i f , a s s u m i n g i t i s g e n e r a t e d e n t i r e l y from the h a n g i n g w a l l , would e n s u r e t h a t the d i l u t i o n would be e n t i r e l y c o n f i n e d w i t h i n the zone of r e l a x a t i o n , F i g u r e 4.14. The zone of r e l a x a t i o n i s more s u i t a b l e a d e s c r i p t o r of the t e n s i l e r e g i o n s i n c e i n o r d e r f o r t e n s i l e s t r e s s e s to e x i s t , the r o c k mass must be a b l e to have a t e n s i l e s t r e n g t h . Brady and Brown (1985) s u g g e s t t h a t the t e n s i l e s t r e n g t h of the r o c k mass i s m i n i m a l i f n o n - e x i s t e n t . T h i s may be t r u e . The a u t h o r , however, b e l i e v e s t h a t a r o c k mass does have some t e n s i l e s t r e n g t h d e p e n d i n g upon i t s r o c k q u a l i t y . The r e a d e r i s r e f e r r e d to a t r e a t i s e on the s u b j e c t by Hoek ( 1 9 8 3 ) . The term zone of r e l a x a t i o n i s t a k e n to mean a zone t h a t i s u n c o n f i n e d , c o n s e q u e n t l y , e n a b l i n g a s t r u c t u r a l b l o c k to be r e l e a s e d under 86 I t s own w e i g h t . The above a n a l y s i s i s b a s e d upon a "k" v a l u e of 2.1. T h i s i s the i n - s i t u s t r e s s as d e t e r m i n e d a t the 660m L e v e l . The d a t a base f o r t h i s s t u d y i s d e r i v e d from s t o p e s r a n g i n g i n d e p t h from s u r f a c e to 430m below s u r f a c e . I t i s p r e d i c t e d t h a t the i n - s i t u s t r e s s r a t i o s w i l l f o l l o w p a t t e r n s s i m i l a r t o t h o s e shown i n F i g u r e 4.4. T h i s would a l t e r the magnitude and l a t e r a l e x t e n t of the zone of r e l a x a t i o n . I t would be i n c r e a s e d s i n c e the h o r i z o n t a l to v e r t i c a l s t r e s s r a t i o i s g e n e r a l l y f o u n d to i n c r e a s e n e a r e r to t h e s u r f a c e , F i g u r e 4.4. A lo w e r s t r e s s r a t i o "k", as shown i n F i g u r e 4.15, would c a u s e the s i d e w a l l s t r e s s e s to be more i n c o m p r e s s i o n than i n t e n s i o n . In a d d i t i o n , the e x t e n t of the zone of r e l a x a t i o n would r e d u c e as shown In F i g u r e 4.16. The a n a l y s i s has been based on a s s u m i n g : - t h a t a p l a n e s t r a i n c o n d i t i o n e x i s t s - o p e n i n g i s w i t h i n an i s o t r o p i c , e l a s t i c and homogeneous medium. The f i r s t c o n d i t i o n assumes t h a t a l l d i s p l a c e m e n t s w i l l o c c u r w i t h i n the p l a n e b e i n g a n a l y z e d , c o n s e q u e n t l y r e s u l t i n g i n the t h i r d d i m e n s i o n b e i n g an i n t e r m e d i a t e p r i n c i p a l p l a n e . T h i s a s s u m p t i o n and i t s i m p l i c a t i o n on the h y p o t h e s i s w i l l be f u r t h e r a n a l y z e d i n the s e c t i o n on 3D mode 1 1 i n g . The second a s s u m p t i o n i s v a l i d to the e x t e n t of what t h i s p a r a m e t r i c s t u d y was i n t e n d e d to show. T h a t was t h a t the h a n g i n g w a l l and 8 7 f o o t w a l l s of the R u t t a n s t o p e s a r e i n a s t a t e of r e l a x a t i o n under the p r e v a i l i n g s t r e s s r e g i m e . The c o n d i t i o n s a l s o e n a b l e the p a r a m e t r i c s t u d y to be r e d u c e d to s t r e s s m a g n i t u d e s t h a t a r e i n d e p e n d e n t of the e l a s t i c c o n s t a n t s . The e f f e c t of r i b and e c h e l o n c o n f i g u r a t i o n s a r e shown by F i g u r e s 4.17,4.18. F i g u r e s 4.17,4.19 and 4.20 show the magnitude of major and m i n o r ( t e n s i l e ) p r i n c i p a l s t r e s s e s s u r r o u n d i n g two and t h r e e s t o p e s l o c a t e d a l o n g s t r i k e . I t d i f f e r s from the base case shown i n F i g u r e 4.21 i n t h a t the h a n g i n g w a l l and f o o t w a l l a r e i n a g r e a t e r t e n s i l e s t a t e . The l a t e r a l e x t e n t of the zone of r e l a x a t i o n has not g r e a t l y i n c r e a s e d beyond t h a t of the base c a s e . T h i s i s due to the i n t e g r i t y of the p i l l a r t h a t i s m o d e l l e d as a r i g i d e l e m e n t . In a c t u a l f a c t , due to the h i g h c o m p r e s s i v e s t r e s s e s i n the r i b p i l l a r s m o d e l l e d , t h e s e p i l l a r s w i l l u l t i m a t e l y c r u s h . The f i n a l s t r e s s c o n f i g u r a t i o n w i l l more c l o s e l y r e s e m b l e t h a t of the i s o l a t e d c a s e w i t h d i m e n s i o n s 8:1 and 12:1 ( s p a n / w i d t h ) . The e c h e l o n c o n f i g u r a t i o n shown i n F i g u r e 4.18 as compared to the base c a s e r e v e a l s t h a t the w a l l c o n t a c t f o r m i n g the l o n g i t u d i n a l p i l l a r i s n o t i n a s t a t e of r e l a x a t i o n , but i n a s t a t e of c o n f i n e m e n t . The s t o p e span t h a t forms the abutment Is i n a l o w e r s t a t e of t e n s i l e s t r e s s than t h a t f o u n d f o r the base c a s e . In a d d i t i o n , the l a t e r a l e x t e n t of the zone of r e l a x a t i o n has been r e d u c e d , F i g u r e 4.20. The e c h e l o n c o n f i g u r a t i o n , F i g u r e 4.18, commences to r e s e m b l e the s t r e s s c 88 c o n f i g u r a t i o n f o r t he 2:1 and 1.3:1 s p a n / w i d t h r a t i o s f o r the i s o l a t e d s t o p e s I n v e s t i g a t e d i n F i g u r e 4 . 1 2 . U l t i m a t e l y , the t e n s i l e r e g i o n s u r r o u n d i n g the f o o t w a l l and h a n g i n g w a l l a b u t m e n t s w i l l be r e p l a c e d by c o m p r e s s i v e s t r e s s e s upon the a d d i t i o n of more e c h e l o n l e n s e s . The e c h e l o n s t o p e s can a l s o be e n v i s i o n e d as b e i n g m i n e d i n a d e s t r e s s e d a r e a w h i c h i s i n the " s t r e s s shadow" o f t h e p r e v i o u s l y mined s t o p e . T h i s r e s u l t s i n an o v e r a l l more s t a b l e s t o p e e x t r a c t i o n c o n f i g u r a t i o n a s s u m i n g t h a t the l o n g i t u d i n a l p i l l a r r e m a i n s i n t a c t and the a r e a to be m i n e d has n o t been g r e a t l y d i s t u r b e d by the e x t r a c t i o n of the a d j a c e n t s t o p e . The m i n i n g o f the s u c c e e d i n g e c h e l o n s t o p e s s h o u l d t h e r e f o r e be f a c i l i t a t e d i n terms of the r e s u l t i n g s t r e s s r e g i m e . The above p a r a m e t r i c s t u d y e n a b l e s o b s e r v a t i o n s made i n s u b s e q u e n t c h a p t e r s to be c o r r e l a t e d to the s t a t e of s t r e s s e n c o m p a s s i n g the i n d i v i d u a l h a n g i n g w a l l and f o o t w a l l c o n t a c t . F u r t h e r a n a l y s i s on t h e e f f e c t of f i l l and s t o p e s e q u e n c i n g w i l l be d i s c u s s e d i n f o l l o w i n g c h a p t e r s . 89 4.3.2.1 V e r i f i c a t i o n o f 3D M odel Brown (1985) s t a t e s t h a t the p l a n e s t r a i n boundary s t r e s s u s u a l l y a p p r o x i m a t e s the c o r r e c t t h r e e - d i m e n s i o n a l s t r e s s e s to w i t h i n l e s s t h a n t e n , and sometimes f i v e per c e n t a t l o c a t i o n s removed by a t l e a s t two e x c a v a t i o n " d i a m e t e r s " from e x c a v a t i o n ends and i n t e r s e c t i o n s . The above i s p a r t i c u l a r l y v a l i d f o r u n i f o r m e x c a v a t i o n c r o s s - s e c t i o n s i e . a x i a l r a t i o s a r e not extreme ( s p a n / w i d t h ) . The r u l e of thumb, "two e x c a v a t i o n d i a m e t e r s " , i s not p a r t i c u l a r l y v a l i d f o r a l l i n - s i t u s t r e s s m a g n i t u d e s and o r i e n t a t i o n s s i n c e i t has been d e r i v e d f o r a c i r c u l a r o p e n i n g i n a u n i - d l r e c t i o n a l s t r e s s f i e l d ( E l I s s a , 1 9 8 0 ) . I t s t a r t s to become i n v a l i d when o p e n i n g s b e g i n to r e s e m b l e a x i s r a t i o s as shown i n F i g u r e 4.22. F i g u r e 4.22 shows how the "end e f f e c t s " of i n d i v i d u a l s t o p e s may come i n t o i m p o r t a n c e i n m o d e l l i n g i n d i v i d u a l p l a n e s . Case A of F i g u r e 4.22 i s t r u l y a p l a n e s t r a i n s i t u a t i o n w i t h r e s u l t a n t i n t e r m e d i a t e s t r e s s e s p a r a l l e l i n g the d i m e n s i o n p e r p e n d i c u l a r to the s t o p e ( z ) . T h i s i s a f u r t h e r a s s u m p t i o n made i n p l a n e s t r a i n and i s g e n e r a l l y v a l i d s i n c e the t h i r d d i m e n s i o n w i l l not r e s u l t i n a s t r e s s c o n c e n t r a t i o n due to f a r removed end e f f e c t s . The r e s u l t a n t s t r e s s w i l l be e q u a l to or l e s s than i n - s i t u s t r e s s p a r a l l e l i n g t h i s d i r e c t i o n . On the o t h e r hand, the s t r e s s e s m o d e l l e d i n the p l a n e s t r a i n w i l l be m o d i f i e d due to s t r e s s c o n c e n t r a t i o n s and r e d i s t r i b u t i o n s o c c u r r i n g w i t h i n t h a t p l a n e . C a s e B of F i g u r e 4.22 shows t h a t e m p l o y i n g a "one 90 or two" e x c a v a t i o n d i a m e t e r zone of i n f l u e n c e , the m o d e l l e d p l a n e w i l l be i n f l u e n c e d by the i n d i v i d u a l end c o n f i g u r a t i o n s . The d i m e n s i o n p e r p e n d i c u l a r t o the p l a n e w i l l a l s o undergo s t r e s s c o n c e n t r a t i o n s and c o n s e q u e n t l y , w i l l n o t n e c e s s a r i l y be an assumed i n t e r m e d i a t e p r i n c i p a l s t r e s s p l a n e upon e x c a v a t i o n . Mathews (1981) has a d o p t e d an a p p r o a c h to m o d e l l i n g open s t o p e s i n a method d i s c u s s e d i n C h a p t e r 3.2 whereby s t r e s s e s i n the s i d e w a l l a r e d e t e r m i n e d e m p l o y i n g a p l a n e s t r a i n a n a l y s i s f o r a h o r i z o n t a l and a v e r t i c a l s e c t i o n t h r o u g h the m i d s p a n of the p a r t i c u l a r w a l l . Mathews employs the l a r g e r of the two v a l u e s i n s u b s e q u e n t a n a l y s e s . The r e s u l t s a r e c a l i b r a t e d to e m p i r i c a l o b s e r v a t i o n s w h i c h i s the method n o r m a l l y employed by p r a c t i o n e r s . The t h r e e d i m e n s i o n a l codes p r e s e n t l y i n use a r e g e n e r a l l y : - d i f f i c u l t to a p p l y - e x p e n s i v e i n terms of computer time usage - r e q u i r e a h i g h d e g r e e of e x p e r i m e n t a l and t h e o r e t i c a l s k i l l (Hoek,1983) In a d d i t i o n , Brady (1985) s t a t e s t h a t " i n the d e s i g n of an u n d e r g r o u n d r o c k s t r u c t u r e , such as a m i n i n g s t r u c t u r e c o n s i s t i n g of a s e t of s t o p e s and p i l l a r s , the system of o p e n i n g s and s u p p o r t members i s f r e q u e n t l y t o o complex to a l l o w a d e q u a t e 3D m o d e l l i n g of the s t r u c t u r e and i t i s n e c e s s a r y to r e s o r t to p l a n e s t r a i n methods of a n a l y s i s " . I t i s the a u t h o r ' s o p i n i o n t h a t upon u n d e r t a k i n g a t h o r o u g h l i t e r a t u r e s e a r c h of 91 t w o d i m e n s i o n a l a n d t h r e e d i m e n s i o n a l c o m p a r i s o n s t h a t : - m i n i m a l p u b l i s h e d w o r k s i f a n y e x i s t o n t h e c o m p a r i s o n o f 2 D a n d 3 D m o d e l s - a c c e p t e d p r a c t i c e i s t o e m p l o y p l a n e s t r a i n a n a l y s i s a n d t o c a l i b r a t e t h e m o d e l . A s i m i l a r a p p r o a c h w a s t a k e n b y C h e n e t a l ( 1 9 8 3 ) w h e r e b y m u l t i p l e s u b - l e v e l o p e n s t o p e s w e r e m o d e l l e d e m p l o y i n g t w o - d i m e n s i o n a l , n o n - l i n e a r e l a s t i c - p l a s t i c f i n i t e e l e m e n t m e t h o d s . I t w a s r e a l i z e d t h a t t h e g e o m e t r y w a s t h r e e - d i m e n s i o n a l a n d t h e m e t h o d e m p l o y e d w a s n o t e n t i r e l y c o r r e c t . H o w e v e r , d u e t o t h e l a r g e c o m p u t e r c o s t s i n c u r r e d w i t h 3 D m o d e l l i n g , t h e r e f o r e l i m i t i n g t h e n u m b e r o f c a s e s t h a t c o u l d b e s i m u l a t e d , t h e i n v e s t i g a t o r s o p t e d f o r a c a l i b r a t e d 2 D p l a n e s t r a i n a n a l y s i s . C h e n ( 1 9 8 3 ) s t a t e s t h a t t h e o r e t i c a l s t u d i e s h a v e s h o w n t h a t s t r e s s c o n c e n t r a t i o n s a r o u n d s y m m e t r i c a l l y s h a p e d o p e n i n g s i n t w o - d i m e n s i o n a l c a s e s a r e a l w a y s s l i g h t l y g r e a t e r t h a n t h o s e i n t h r e e - d i m e n s i o n a l . F i g u r e 4 . 2 3 s h o w s a n e x a m p l e o f f i v e a d j a c e n t s t o p e s t h a t f o r m p a r t o f a m u c h l a r g e r m i n i n g b l o c k o f t h e M t . . I s a m i n e . T h e e x t r e m e a x i a l r a t i o s a n d g e o m e t r i c i r r e g u l a r i t y r e q u i r e d t h a t a c o m p l e t e t h r e e - d i m e n s i o n a l a n a l y s i s b e c a r r i e d o u t t o a c c u r a t e l y d e t e r m i n e t h e t r u e p i l l a r b o u n d a r y s t r e s s e s . T h e m a j o r a n d m i n o r p r i n c i p a l i n - s i t u s t r e s s e s a r e i n t h e " x z " o p l a n e w i t h a n d ^ 3 r o t a t e d c l o c k w i s e b y 2 5 f r o m t h e x a n d z a x e s , r e s p e c t i v e l y . T h e i n t e r m e d i a t e p r i n c i p a l i n - s i t u s t r e s s a c t s i n t h e y d i r e c t i o n . T h e t h r e e - d i m e n s i o n a l s t r e s s a n a l y s i s 9 2 c a r r i e d out by Watson and C o w l i n g (1985) gave : - Lower maximum s t r e s s c o n c e n t r a t i o n s t h a n t h o s e which were c a l c u l a t e d by use of p l a n e s t r a i n a p p r o x i m a t i o n s . - The e f f e c t of the g r o u p of o p e n i n g s on the s t r e s s f i e l d was f o u n d to be more l o c a l i z e d i n t h r e e - d i m e n s i o n a l than i n t w o - d i m e n s i o n a l s o l u t i o n s . A t h r e e d i m e n s i o n a l s o l u t i o n was a t t e m p t e d f o r t h i s s t u d y by e m p l o y i n g "3DBELM". The o b j e c t i v e of t h i s p o r t i o n of the s t u d y was to show t h a t the h a n g i n g and f o o t w a l l i s p r i m a r i l y i n a s t a t e of r e l a x a t i o n and c o n s e q u e n t l y , d i l u t i o n i s a t t r i b u t e d to the r e l e a s e of s t r u c t u r a l b l o c k s under g r a v i t y . The e x i s t i n g - 1 i t e r a t u r e on t h r e e - d i m e n s i o n a l m o d e l l i n g i s m i n i m a l and too g e n e r a l i n s u b s t a n c e . A t h r e e - d i m e n s i o n a l a p p r o a c h was a p p l i e d t o the base c a s e shown i n F i g u r e 4.21. A s t o p e 30m high,20m i n span and 5m i n w i d t h was g e n e r a t e d . These d i m e n s i o n s a r e s i m i l a r to the a c t u a l a x i s r a t i o s t h a t e x i s t a t R u t t a n . F i g u r e 4.24 shows the model employed w i t h the t r i a n g u l a r s u r f a c e e l e m e n t s I n d i c a t e d . I n - s i t u s t r e s s e s as d e t e r m i n e d p r e v i o u s l y were emplo y e d : - x d i r e c t i o n 2 . 5 ^ v - y d i r e c t i o n 1.2 ^ v. . - z d i r e c t i o n 0 .8 <^ v S e v e n t y (70) nodes t r i a n g u l a r e l e m e n t s were and one hundred and t h i r t y - s i x e m p l o y e d . The c o s t of r u n n i n g (136) t h i s 93 program on the U.B.C. Amhdahl 580/5850 system was $40.00 or i n terms of CPU time e q u a l to 120 s e c o n d s . The r a t e s a r e based on UBC c h a r g e s of $480/hr CPU time ( n o r m a l p r i o r i t y ) and a f a c t o r of 3.2 which r e p r e s e n t s a d d i t i o n a l c h a r g e s f o r memory usage and f i l e i n p u t / o u t p u t . C ommercial b u r e a u r a t e s would be f i v e t i m e s t h i s amount. V e r t i c a l and h o r i z o n t a l s e c t i o n s of the g e n e r a t e d s t r e s s d i s t r i b u t i o n s were p r o d u c e d as shown i n F i g u r e s 4.25,4.26. S t r e s s m a g n i t u d e s i n terms of ,<fy ,£z and ^\ , <4 2 , 3 were d e t e r m i n e d a t v a r i o u s i n t e r v a l s on and e x t e r n a l to the b o u n d a r y . F i g u r e 4.25a shows t h a t the t a n g e n t i a l s t r e s s e s a t the m i d p o i n t of the h o r i z o n t a l p l a n e a r e i n t e n s i o n i n e i t h e r d i r e c t i o n w i t h i n the " y z " p l a n e (<5y=^3 = -49 MPa ,^z= <42 = -27 MPa). The e x t e n t of the r e l a x e d zone has been c o n t o u r e d and r e p r e s e n t s the f u r t h e s t e x t e n t t h a t t e n s i o n i s o b s e r v e d . T h i s t e n s i o n i s r e c o r d e d w i t h i n the "xy" p l a n e . The m a g n i t u d e s and r e l a x e d zone d i s t r i b u t i o n t e n d to be extreme when r e l a t e d to the base c a s e 2D-plane s t r a i n a n a l y s i s , F i g u r e 4.21. Reasons f o r t h i s a r e as f o l l o w s : l e n g t h - end e f f e c t s n o t a c c o u n t e d f o r mesh i s p a r t i c u l a r l y c o a r s e s i n c e e a c h element i s 5m i n the A f u r t h e r a n a l y s i s was c o n d u c t e d whereby the h e i g h t of s t o p e was e x t e n d e d to 300m w i t h the r e m a i n i n g p a r a m e t e r s 94 unchanged. The h o r i z o n t a l p r o f i l e H-H' i s shown i n F i g u r e 4.25b f o r the m o d i f i e d g e o m e t r y . A c o m p a r i s o n i s as f o l l o w s between 2D and the 3D m o d e l s : Comparison 2D 3D T a n g e n t i a l s t r e s s m i d - s p a n -9MPa -7MPa (^3= -9 MPa) E x t e n t of r e l a x e d zone .55W ,6W (W=stope w i d t h ) The c o n t o u r s drawn i n F i g u r e 4.25 r e f e r to the t a n g e n t i a l s t r e s s e s on the b o u n d a r y and the minor p r i n c i p a l s t r e s s e s o f f the b o u n d a r y . The m i n o r p r i n c i p a l s t r e s s was f o u n d to be c o n s i s t e n t l y l o c a t e d w i t h i n the "xy" p l a n e . The i n - s i t u minor p r i n c i p a l s t r e s s i s o r i e n t e d i n the " z " d i r e c t i o n p r i o r to e x c a v a t i o n and upon e x c a v a t i o n becomes the i n t e r m e d i a t e s t r e s s d i r e c t i o n . T h i s has been d i s c u s s e d p r e v i o u s l y . The above c o m p a r i s o n does i n d i c a t e the i m p o r t a n c e of end e f f e c t s , however, the a u t h o r must c a u t i o n the r e a d e r i n p o i n t i n g out t h a t the m a g n i t u d e s of the c o a r s e r mesh a r e e x t r e m e . A v e r t i c a l s e c t i o n was a l s o a n a l y z e d w i t h the o r i g i n a l s t o p e c o n f i g u r a t i o n , F i g u r e 4.26. The m a g n i t u d e s a g a i n a r e extreme, however, the zones of r e l a x a t i o n can be c o n t o u r e d and r e p r e s e n t e d as shown i n F i g u r e 4.27. F i g u r e 4.28 shows the m o d e l l e d s t o p e o u t l i n i n g the e l e m e n t s which a r e i n a c o m p l e t e s t a t e of r e l a x a t i o n . F i n e r meshes or more complex g e o m e t r i e s were not m o d e l l e d i n t h r e e - d i m e n s i o n s due to the h i g h computer c o s t s and time of p r e p a r a t i o n i n v o l v e d . Two s t o p e s h a v i n g s i m i l a r c o a r s e 95 meshes to t h a t p r e v i o u s l y m o d e l l e d would c o s t $200 per r u n . I t i s assumed t h a t the r e s u l t s g e n e r a t e d , however, would not a l t e r the p r e m i s e t h a t the HW/FW a r e i n a s t a t e of r e l a x a t i o n . 4.3.2.2 O b s e r v a t i o n a l Approach In a d d i t i o n to the a n a l y t i c a l a p p r o a c h d i s c u s s e d p r e v i o u s l y , measurements and o b s e r v a t i o n s were made a t R u t t a n to r e i n f o r c e the p r e m i s e t h a t the w a l l c o n t a c t s a r e i n a s t a t e of r e l a x a t i o n . E x t e n s o m e t e r s and s t r e s s m e t e r s were i n s t a l l e d a t the i n c e p t i o n of u n d e r g r o u n d m i n i n g , March 1979, l n o r d e r to m o n i t o r the f i r s t s t o p e s mined. S t r e s s m e t e r s t h r o u g h o u t the mine were e v a l u a t e d i n o r d e r to u n d e r s t a n d the mechanism of s t r e s s t r a n s f e r t h a t o c c u r s due to m i n i n g . The f o l l o w i n g a r e a s were a n a l y s e d : - 400mL west l e n s e s e x t r a c t i o n , F i g u r e 4.29 - 340mL west l e n s e s e x t r a c t i o n - 340ml e a s t l e n s e s e x t r a c t i o n V i b r a t i n g w i r e s t r e s s m e t e r s ( I r a d , 1 9 7 7 ) and e x t e n s o m e t e r s ( Smith,1976) were employed. The s t r e s s m e t e r s were a b l e to measure d i r e c t i o n a l change i n s t r e s s and were o r i e n t e d as shown i n F i g u r e 4.29. They were l o c a t e d p r i m a r i l y i n p i l l a r c r o s s - c u t s and f o o t w a l l and h a n g i n g w a l l d r i v e s . O r i e n t a t i o n s were e i t h e r n o r t h - s o u t h ( N ) , e a s t - w e s t ( E ) or v e r t i c a l ( V ) . The e x t e n s o m e t e r s were l o c a t e d p e r p e n d i c u l a r to ore c o n t a c t s 96 and w i t h i n p i l l a r s . The r e s u l t s were a n a l y z e d as p a r t of t h i s s t u d y i n o r d e r to e s t a b l i s h a mechanism of s t r e s s d i s t r i b u t i o n by o b s e r v a t i o n . P r o b l e m s t h a t o c c u r r e d w i t h the a n a l y s i s a r e i n t h e : - poor l o c a t i o n of c e r t a i n s t r e s s m e t e r s i e . a t c o r n e r s of o p e n i n g s - s t r e s s m e t e r s n o t o r i e n t e d i n the d i r e c t i o n t h a t would y i e l d maximum b e n e f i t f o r i n t e r p r e t a t i o n - e x t e n s o m e t e r s d r i l l e d to l e n g t h s t h a t e x c e e d e d 100m w h i c h a r e e x c e s s i v e i n terms of g i v i n g r e l i a b l e and r e p e a t a b l e r e s u l t s Upon e x c a v a t i o n , the n o r t h / s o u t h and e a s t / w e s t s t r e s s m e t e r s l o c a t e d i n the v i c i n i t y of the h a n g i n g w a l l and f o o t w a l l d e c r e a s e d , F i g u r e s 4.30,4.31. E x t e n s o m e t e r s i n d i c a t e d t h a t upon e x t r a c t i o n , the HW/FW commenced c o n v e r g i n g towards the o p e n i n g , F i g u r e 4.32. An i n v e s t i g a t i o n of s t o p e s e q u e n c e , G o l d b e c k (1985 ) , was a n a l y t i c a l l y a s s e s s e d e m p l o y i n g the BITEM c o d e . F i g u r e 4.33 i s a t y p i c a l e x t r a c t i o n s equence a t R u t t a n g e n e r a l l y d u p l i c a t i n g the c o n f i g u r a t i o n a n d " e x t r a c t i o n s equence of the . s t o p e s p r e v i o u s l y i d e n t i f i e d . I n d i v i d u a l o b s e r v a t i o n p o i n t s were a n a l y z e d and f o r p u r p o s e s of t h i s t h e s i s , o n l y the h a n g i n g w a l l o b s e r v a t i o n s w i l l be r e p r o d u c e d . A d e t a i l e d a n a l y s i s i s f o u n d i n " A n a l y s i s of ' S t r e s s Changes a t R u t t a n Mine" by G o l d b e c k ( 1 9 8 5 ) . L o c a t i o n "A and C" i s shown In F i g u r e 4.34b, i n d i c a t i n g t h a t upon e x c a v a t i o n i n the v i c i n i t y of the 9 7 o b s e r v a t i o n p o i n t s , the n o r t h / s o u t h s t r e s s e s d e c r e a s e . P r i o r to e x c a v a t i o n , a s t r e s s b u i l d u p i s o b s e r v e d as shown i n l o c a t i o n C f o r c u t s 1 t h r o u g h 5. S i m i l a r l y f o r the e a s t / w e s t s t r e s s e s , F i g u r e 4.34b, a l a r g e t e n s i l e s t r e s s change i s o b s e r v e d upon e x c a v a t i o n . The r e s u l t s have been p l o t t e d i n terms of change of s t r e s s from I n - s i t u , i n o r d e r to be r e l a t e d to the r e c o r d e d s t r e s s g a u g e s . A q u a n t i t a t i v e a s s e s s m e n t may be made, however, f o r p u r p o s e s of t h i s s t u d y , i t i s s u f f i c i e n t to say t h a t " the h a n g i n g w a l l and f o o t w a l l a r e a n a l y t i c a l l y shown to be i n a r e l a x e d s t a t e " . A p h o t o g r a p h d e p i c t i n g the e f f e c t of s t o p e r e l a x a t i o n i s shown i n F i g u r e 4.35. I n i t i a l l y , the r o c k mass e x h i b i t e d c l o s e d j o i n t s and upon e x c a v a t i o n of the a d j a c e n t s t o p e , j o i n t s e p a r a t i o n o c c u r r e d . F i g u r e 4.35 shows j o i n t s p a r a l l e l i n g the h a n g i n g w a l l of 320-12B s t o p e on the 240m l e v e l . 4.4 C o n c l u s i o n The p u r p o s e of t h i s c h a p t e r was to p r o v e an i m p o r t a n t a s s u m p t i o n i n o r d e r to employ the d a t a base under the premise t h a t f a i l u r e i s k i n e m a t i c a 1 l y c o n t r o l l e d . Subsequent c h a p t e r s w i l l show t h a t a d v e r s e l y o r i e n t e d d i s c o n t i n u i t i e s e x i s t ' a n d . a r e p r i m a r i l y r e s p o n s i b l e f o r the r e s u l t a n t d i l u t i o n . The degree of d i l u t i o n w i l l t h e n be r e l a t e d to p a r a m e t e r s t h a t w i l l have the g r e a t e s t impact on i t s m a g n i t u d e , s t r e s s not b e i n g one of t h o s e f a c t o r s . The r e l a x e d zone was c o n c l u d e d i n t h i s c h a p t e r to encompass a l l I s o l a t e d , r i b , and e c h e l o n s t o p e s h a v i n g c o n f i g u r a t i o n s r e s e m b l i n g t h o s e of R u t t a n . The r e s u l t a n t d i l u t i o n s a r e w e l l w i t h i n the z o n e s of r e l a x a t i o n and c o n s e q u e n t l y a r e n o t c o n s i d e r e d to be g r e a t l y e f f e c t e d by g e o m e t r y . T h i s w i l l be d i s c u s s e d f u r t h e r i n C h a p t e r 6, " D i l u t i o n " . T a b l e 4.1: T i t l e : Boundary Integral Technique for Multiple Materials Program: BITEM Capacility: Solves two-dimensional e l a s t i c i t y problems for a piecewise homogeneous, isotropic e l a s t i c s o l i d using the boundary integral equation method with linear variation of displacements and tractions along the boundary segments, and allowing mixed displacement and traction boundary conditions. The s o l i d may be composed of at most five homogeneous regions with d i f f e r i n g e l a s t i c constants. Problem symmetry can be taken into account. F a c i l i t i e s for automatic data generation are available. Input: Problem geometry - node coordinates, symmetry properties. E l a s t i c properties of each homogeneous region. Nodel boundary conditions. Points within s o l i d at which stress and displacement solutions required. Output: Statement of input data, plus data generated by the problem. Tractions and displacements on a l l boundaries of the problem. Stress and displacement solutions for selected i n t e r i o r points. Language: ANSI FORTRAN IV Origin: BITEM was written at the CSIRO d i v i s i o n of Applied Gcomechanics and i s based on program BITE which analyses homogeneous solids only. Refer Crotty and Kardle (1977) and Riccardella (1973). The program was converted from CDC to IBM FORTRAN by R. Pakalnis (1983), University of B r i t i s h Columbia. Information: Further information may be obtained from -Commonwealth S c i e n t i f i c and Industrial Research Organization Institute of Earth Sciences Division of Applied Geomcchanics P.O. Box 54 Mount Kaverley, Vic. 3249 Aus t r a l i a Mining and Mineral Process Engineering Dpt. 6350 Stores Road University of B.C. Vancouver, B.C. V6T 1WS Canada Documentation: CSIRO and supplemented by work of R. Pakalnis, University of B r i t i s h Columbia C o d e T i t l e : Three D i m e n s i o n a l Boundary Element Program f o r M i n i n g A p p l i c a t i o n s Program: 3 D B ELM C a p a c i t y : Program models a t h r e e - d i m e n s i o n a l boundary by p i e c e w i s e f l a t t r i a n g l e s over which the d i s p l a c e m e n t s and t r a c t i o n s v ary l i n e a r l y . The boundary may be composed of m u l t i p l e openings w i t h i n a s i n g l e homogeneous r e g i o n . Problem symmetry can be taken I n t o a c c o u n t . Input: Problem geometry - node c o o r d i n a t e s , symmetry p r o p e r t i e s . E l a s t i c p r o p e r t i e s of the homogeneous r e g i o n . Nodel boundary c o n d i t i o n s . P o i n t s w i t h i n s o l i d at which s t r e s s and d i s p l a c e m e n t s o l u t i o n s r e q u i r e d . Output: Statement of Input d a t a , p l u s data g e n e r a t e d by the problem. T r a c t i o n s and d i s p l a c e m e n t s on a l l b o u n d a r i e s of the problem . Ax , ^ y , Az , A xy , A xz , A y z , A oc t , A]normal. S t r e s s and d i s p l a c e m e n t s o l u t i o n s f o r s e l e c t e d I n t e r i o r p o i n t s . Language: ANSI F o r t r a n IV O r i g i n : 3DBELM was w r i t t e n at the CSIRO D i v i s i o n o f A p p l i e d Geomechanlcs and Is based on program B i t e which a n a l y s e s homogeneous s o l i d s . R e f e r C r o t t y and Wardle (1977) and R i c c a r d e l l a (1973). The program was c o n v e r t e d from CDC to IBM FORTRAN by R. P a k a l n 1 s ( 1 983 ) , U n i v e r s i t y of B r i t i s h C o l u n b l ; 100 shear tensile (van, dyke) Figure 4.1: F r a c t u r e P a t t e r n Caused by Crushing of a C y l i n d e r ( r e f e r t o s e c t i o n 4.2.1) Figure 4.2: P o s s i b l e E x p l a n a t i o n f o r the Formation of F o l i a t i o n P l a t e l e t s ( r e f e r t o s e c t i o n 4.2.1) 101 69-I 1 M 1 * 3 £ 18 i » Vertical t i r e s . ffx(MPi) • CSIRO 2 RESULT C J , ' 0 . 0 2 7 1 • Australia » Canada • United States o Scandinavia • Southern Atrba o Other regions F i g u r e 4.3: V e r t i c a l S t r e s s Vs Depth (Hoek, 1983) RATIO AVERAGE HORIZONTAL /VERTICAL STRESS OS 08 10 12 14. . 16 18 20 22 24 26 28 1 •1 ' i y • • ' ' 800 loooi 1200 1400 I60O I80O 2O0O 220O 2400-2600-• • •% • • e 251-6 8_ T i j 5 ^ " 0»pih(m) 4 1.14 • • • • . —CANADIAN SHIELD STRESS MEASUREMENTS • - RUTTAN STRESS MEASUREMENTS +- TESTS PERFORMED 1986 F i g u r e 4.4: H o r i z o n t a l S t r e s s Vs Depth ( H e r g e t , 1980) 102 L E G E N D F i g u r e 4.5: S t r e s s Measurement L o c a t i o n (E = 70 GPa, u= 0.18, Z = 661m) TEST NUMBER PRINCIPAL STRESSES o l BRG DIP 02 BRG DIP 03 BRG DIP VERT STRESS 0 V MPa HORIZONTAL STRESSES •K' FACTOR 0 v o2 O V 03 Ov *A % DIFF o v Theor *B % DIFF ^ Theoi a v (Mean) o l MPa o 2 MPa 0 3 MPa MPa Ohl l * MPa O h i Ohll o h avg o v o v o v IA 96 31 27 344 -18 85 -30 226 -54 35 89 30 2.6 0.9 1.8 2.8 0.9 0.8 93% 2 0 % IB 121 32 28 340 -19 81 -30 221 -54 39 110 31 2.8 0.8 1.8 3.1 0.8 0.7 119% 20% 2 46 27 15 341 -24 231 -38 95 -43 25. 41 22 1.7 0.9 1.3 1.8 1.0 0.5 38% -13% Less ^G8 45 21 14 346 -17 248 -26 106 -59 18 42 19 2.4 1.1 1.8 2.5 1.2 0.8 0% 20% G8 z Avg 45 20 14 347 -16 250 -23 109 -61 17 42 19 2.4 1.1 1.8 2.5 1.2 0.8 4% 20% 3A 63 28 26 342 -22 74 -4 174 -68 30 59 28 1.9 0.9 1.4 2.1 0.9 0.8 70% -7 % 3B 65 29 25 347 -22 79 -6 185 -67 30 59 30 1.9 1.0 1.5 2.2 1.0 0.8 68% 0% _L : Horz. S t r e s s P e r p e n d i c u l a r to Orebody T r e n d 340/0° II : Horz. S t r e s s P a r a l l e l t o T r e n d 70/0° *A o v T h e o r e t i c a l = 18 MPa *B Oh Ov T h e o r e t i c a l = 1 . 5 Figure 4.6: CSIRO S t r e s s Magnitudes and O r i e n t a t i o n s 103 o.o 5C o O -I 73 5 ° > O ° 5.5 I OVERCORE DISTANCE (CM) 110 16.5 22.0 27.5 33.0 38.5 - > 1 1 1 1 1 I I I I I i 44.0 _! L AXIAL 1,7 CIRC. 2,6,8 ANG. 3,5,4,9 49.5 _ l 55.0 _ J F i g u r e 4.7: CSIRO T e s t #2 - Overcore D i s t a n c e Vs. R e l e a s e d S t r a i n 6 % R U T T A N F i g u r e 4.8: Measured P r i n c i p a l S t r e s s D i r e c t i o n s and S u g g e s t e d D i r e c t i o n o f C o m p r e s s i o n D u r i n g T e c t o n i c D e f o r m a t i o n ( H e r g e t , 1980) 104 2.0 v\lp 1.0 - 1 . 0 1 K = 0.5 1.0 \ . 1.5 1 2.0 1 L . I 1 T 1 T 1 1 I n J A r f t 10 mw 20 F i g u r e 4.9: S i d e w a l l S t r e s s e s as a F u n c t i o n of Opening Geometry and A p p l i e d I n - S i t u S t r e s s (Bray, 1985) b. I ^ CT3-0.8 CTv K v e r t . plane = 2 5 0 ~ V 0.8 = 3.1 K h o r i z . plane = 2.5g*V 1.2 cr v = 2.1 CT2- |.2tTv F i g u r e 4.10: H o r i z o n t a l / V e r t i c a l S t r e s s R a t i o (k) C. Si I, i width 2.5CTV cTt span 1.2 o-V K = 2. S P A N / W l O f H R A T I O Figure 4.11: T a n g e n t i a l HW/FW S t r e s s Vs Span/Width 106 2.5SV SPAN/WIDTH RATIO F i g u r e 4.13: L a t e r a l Extent o f T e n s i l e Z -ASSUMPTIONS- ALL DUJT10N OCCURS FROM ONE WALL MAXMJM fXUTION IS 20% TENSLE ZONE 20V. DILUTION SPAN/WIDTH • 2'l PLAN view MOCdJNC T E N S L E S T R E S S REGION A R O U N D O P E N I N G - V A R I A B L E S H A P E . 7 " SPAN/WIDTH >4'l SPAN/WIDTH" 8>l • EQUIVALENT TO 21V. BY VOLL.C F i g u r e 4.14: R e l a t i o n s h i p Between D i l u t i o n and T e n s i l e Zone 107 STRESS RATIO (K) F i g u r e 4.15: E f f e c t of "k" on the T a n g e n t i a l S t r e s s i n the Ftf/HU r KffH I (W) WIDTH t | n <5"H SPAN n : Lateral extent of tens i le z o n e SPAN/WIDTH = 4 STRESS R4TCC (K) F i g u r e 4.16: Extent of L a t e r a l T e n s i l e Zone with Variance i n "k' 108 F i g u r e 4.17: S t r e s s C o n f i g u r a t i o n - R i b S t o p e s 109 110 2 . 5 S V 1 1 - 2 i NUMBER OF OPENINGS • NUU. ECHELON STOPES + NUU. Of RIB STOPES F i g u r e 4.19: V a r i a t i o n o f T a n g e n t i a l S t r e s s w i t h Number o f Op e n i n g s 2.5 <rv 1 2 i NUMBER OF OPENIHCS • RIB STOPES + ECHELON STOPES F i g u r e 4.20: V a r i a t i o n o f L a t e r a l E x t e n t o f T e n s i l e Zone w i t h Number of Openings Figure 4.23: Stope Geometry - Mount Isa Mine, analysed by 3D-Boundary Element (Brown, 1985) 112 F i g u r e 4.24: 3D M o d e l l e d Stope 113 A ) STOPE 3 0 m HIGH B) STOPE 3 0 0 m HIGH ( 4 0 , 0 , 9 ) ( 6 , - 9 , - 4 ) ( 4 0 , 0 > 2 8 ) ( - 7 / ) . I ) ( 7 5 , - 1 9 , 1 5 ) ( 3 5 . 2 , 9 ) ( 1 8 , - 4 , 4 ) • * — ( t T l , 0 * 3 , C T 2 ) * • ( 3 9 , - 2 , 1 1 ) ( 3 1 . 9 , 1 3 ) ( 2 0 , 5 , 8 ) ( 1 2 , 4 3 , 1 5 ) ( I 7 , l 9 , 9 j \ j 8 , - 3 f 4 ) * — ( < T Y , « - X , fZ ) ->• ( 1 2 , 2 5 , 1 3 ) ( 1 6 , 2 2 , 1 4 ) ( 1 9 , 6 , 8 ) M P a T E N S I L E Z O N E Y , X P L A N E ( 4 3 , - 2 , 1 0 ( 2 8 , 1 1 , 1 3 ) ( 2 6 , 1 1 , 1 5 ) • • • ( 1 1 , 2 9 , 1 2 ) ( 1 3 , 2 7 , 1 2 ) ( 1 5 , 2 5 , 1 2 ) ( 3 9 , - 3 , 1 3 ) ( 2 6 , 1 1 , 1 3 ) ( 2 3 , 1 1 , 1 6 ) • • • ( 1 2 , 2 4 , 1 2 ) ( 1 3 , 2 4 , 1 2 ) ( 1 7 , 2 1 , 1 2 ) F i g u r e 4.25: E x t e n t o f T e n s i l e Zone - h o r i z o n t a l P l a n e H - H' ( 4 0 , 0 , - l 3 ) f ( 4 2 , 0 , - 1 2 ) ( 5 1 , 2 1 , 4 ) ( 2 0 , 3 6 , 2 1 ) ( 0 , - 2 3 , - 3 1 ) ^ ( - 2 3 , 0 , - 3 0 ^ • • ( 2 2 , 5 , - 1 ) • ( 2 , - 4 , 1 8 ) ( 3 2 , I 5 J 0 ) * ( I I , 3 1 , 1 5 ) ( 0 , - 2 5 , - 4 l ) | ( - 2 4 , 0 , - 4 8 ) • • ( 1 8 , 4 , - 4 ) • ( 4 , - 3 , 1 8 ) ( 2 5 . I 5 , I I ) « ( 1 2 . 2 6 , 1 5 ) T E N S I L E Z D N E X . Z P L A N E ( < r i , < T 2 , < T 3 ) • (crz.crx, 0 " Y ) M P a F i g u r e 4.26: E x t e n t o f T e n s i l e Zone - V e r t i c a l P l a n e V - V z A 115 Figure 4 . 2 9 : Mining Sequence and Instrumentation - 400m Level STRESS METER LOCATION — DIRECTION W - E I DIRECTION N - S • DIRECTION VERTICAL EXTENSOMETER Figure 4.31: Gauge 3EW Located i n FW of 14D on 400m Level 117 F i g u r e 4.32: Extensoraeter Located at FW Contact of 13D Stope on . 400m Le v e l h D-»-2 | ?4 i j 7 j'6j 8 10 III E i i •5 i , 4 ,3. if II: 5 A T4 i. rV— |3 j l j g l o r r \ F i g u r e 4 . 3 3 : Modelled Sequence o f E x t r a c t i o n - Plan View LOf.ATIOM A UrS SIBESS 30 METEB ST QBE. 10 F i g u r e 4 . 3 4 a : S t r e s s Change Vs E x t r a c t i o n Stage - NS LOCATION A IS. C-W STRF<:<! 30 MEIER-SIQEE. L O C A T I O N r. E-w <JTRF<;<; I 3 0 M F T F P . S T f l P F '5 I F i g u r e 4.34b: S t r e s s Change Vs E x t r a c t i o n Stage - EU 121 CHAPTER F I V E ROCK MASS CHARACTERIZATION 5.1 I n t r o d u c t i o n T h i s c h a p t e r i d e n t i f i e s the p a r a m e t e r s d e s c r i b i n g the r o c k mass t h a t have the g r e a t e s t i n f l u e n c e upon s t o p e d i l u t i o n . I t b e g i n s w i t h a c r i t i c a l e v a l u a t i o n of e x i s t i n g r o c k mass c l a s s i f i c a t i o n s y s t e m s . A p a r t i c u l a r s y s t em was s e l e c t e d i n o r d e r to r e l a t e the r o c k q u a l i t y of i n d i v i d u a l s t o p e s a t R u t t a n to a much l a r g e r d a t a base t h a t has b e e n d e r i v e d t h r o u g h o u t the l i t e r a t u r e . T h i s e n a b l e s the r o c k q u a l i t y to be e v a l u a t e d q u a n t i f i a b l y i n te rms of e x i s t i n g r e l a t i o n s h i p s t h a t have been d e v e l o p e d by o t h e r i n v e s t i g a t o r s . The s i g n i f i c a n c e of the p a r a m e t e r s i n c o r p o r a t e d i n t o the c l a s s i f i c a t i o n a r e s u b s e q u e n t l y a n a l y z e d i n o r d e r to a s s e s s t h e i r r e l a t i v e i m p o r t a n c e i n te rms of s t o p e d e s i g n a t R u t t a n , C h a p t e r 7 . A s t r u c t u r a l a s s e s s m e n t , i n t e rms of d e l i n e a t i n g p o t e n t i a l f a i l u r e modes of i n d i v i d u a l s t o p e h a n g i n g w a l l and f o o t w a l l c o n t a c t s , i s p r e s e n t e d . A k i n e m a t i c a n a l y s i s i d e n t i f i e s s t r u c t u r e as b e i n g a p r i n c i p a l f a c t o r a f f e c t i n g d i l u t i o n . 5.2 Rock Mass C l a s s i f i c a t i o n Rock mass c l a s s i f i c a t i o n s y s t e m s have been d e v e l o p e d 122 p r i m a r i l y to a s s i s t i n recommending s u p p o r t f o r u n e r g r o u n d c i v i l p r o j e c t s . G e n e r a l l y , c i v i l s t r u c t u r e s a r e n o r m a l l y i s o l a t e d from any n e a r b y o p e n i n g s , do not a c c o u n t f o r the e x t r a c t i o n p r o c e s s , a r e a t moderate t o s h a l l o w d e p t h , and expose a minimum of open g r o u n d . These d e f i c i e n c i e s do not e n a b l e them to be d i r e c t l y a p p l i e d t o , t h e d e s i g n of u n d e r g r o u n d m i n i n g s t r u c t u r e s . The c l a s s i f i c a t i o n s , a l t h o u g h on t h e i r own ar e n o t adequate to p r e d i c t mine d e s i g n r e q u i r e m e n t s , do p r o v i d e a p r o c e d u r e f o r i n v e s t i g a t i o n . The r o c k mass c l a s s i f i c a t i o n systems of p a r t i c u l a r r e l e v a n c e to u n d e r g r o u n d m i n i n g a p p l i c a t i o n s a r e t h e : - G e o m e c h a n i c a l C l a s s i f i c a t i o n System (RMR) (1973) - Q System (1974) These systems have e m p i r i c a l l y e v o l v e d from a l a r g e d a t a b a s e . In a d d i t i o n , t h e y n o t o n l y r e f l e c t the e x p e r i e n c e s of the d e v e l o p e r s , but a l s o the p r e c e d i n g i n v e s t i g a t o r s such as T e r z a g h i ( 1 9 4 6 ) , L a u f f e r ( 1 9 5 8 ) , S t i n i ( 1 9 5 0 ) , Deere ( 1 9 6 4 ) , Wickham et a l (1972) among o t h e r s . The systems were p r i m a r i l y d e r i v e d f o r the d e s i g n of c i v i l e n g i n e e r e d t u n n e l s . However, they p r o v i d e the b a s i s f o r s u b s e q u e n t m o d i f i c a t i o n s t h a t e n a b l e them to be a p p l i e d to m i n i n g . L a u b s c h e r ( 1 9 7 6 ) , Mathews et a l ( 1 9 8 1 ) , K e n d o r s k i ( 1 9 8 3 ) , and Hoek (1983) have a p p l i e d a d j u s t m e n t s to the e x i s t i n g systems t o a i d i n the d e s i g n of m i n i n g s t r u c t u r e s . 1 2 3 An i d e a l mine c l a s s i f i c a t i o n s ystem must have the f l e x i b i l i t y t h a t a l l o w s i t to be used f o r v a r i o u s mine a p p l i c a t i o n s , and i t must be s i m p l e so t h a t i t can be e a s i l y a s s e s s e d and u n d e r s t o o d . I t i s o n l y i n t h i s manner t h a t i t can f u n c t i o n as an i m p o r t a n t t o o l i n the d e s i g n and o p e r a t i o n of a mine. The RMR and Q Systems s a t i s f y the above c r i t e r i a . D e f i c i e n c i e s dp e x i s t w i t h the two c l a s s i f i c a t i o n s , but t h r o u g h a d j u s t m e n t s , one i s a b l e to overcome the c r i t i c i s m s . In p a r t i c u l a r the Q System i s s a i d to be too r i g o r o u s ( K e n d o r s k i , 1 9 8 3 ) , has a p o o r l y d e f i n e d f a c t o r t h a t a c c o u n t s f o r s t r e s s , and does n o t a c c o u n t f o r s t r u c t u r a l o r i e n t a t i o n . These c r i t i c i s m s a r e i n c o r p o r a t e d i n t o a d j u s t m e n t s by Mathews (1981) and K i r s t e n ( 1 9 8 3 ) . The RMR s y s t e m i s s a i d to be too s i m p l e ; i t does n o t a c c o u n t f o r s t r e s s and the i n p u t p a r a m e t e r s a r e too q u a l i t a t i v e . These l i m i t a t i o n s a r e i n c o r p o r a t e d i n t o a d j u s t m e n t s by L a u b s c h e r ( 1 9 7 6 ) , K e n d o r s k i ( 1 9 8 3 ) . A c l a s s i f i c a t i o n system f o r the R u t t a n o p e r a t i o n s h o u l d be p a t t e r n e d a f t e r the "Q or RMR" s y s tems w i t h the r e l e v a n t g e o t e c h n i c a l p a r a m e t e r s a s s o c i a t e d w i t h each m i n i n g method i d e n t i f i e d . T h i s r e q u i r e s the g e n e r a t i o n of a l a r g e e m p i r i c a l d a t a base s p e c i f i c a l l y c a t e g o r i z e d i n terms of s i m i l a r i t i e s of a p p l i c a t i o n s f o r open s t o p e d e s i g n . T h i s d a t a base was e q u a l l y s p a r s e when T e r z a g h i p r o p o s e d h i s system i n 1946. T h i s d a t a base has s i n c e expanded and grown and the systems have been r e f i n e d due to i t s a c c e p t a n c e among the c i v i l e n g i n e e r i n g community. T h i s was l a r g e l y due to the c o n t i n u e d s u c c e s s 124 a c h i e v e d i n t u n n e l s u p p o r t p r e d i c t i o n . One of the m a j o r d i f f e r e n c e s between the c i v i l and m i n i n g d i s c i p l i n e s i s the r e q u i r e m e n t of mines to g e n e r a l l y o p e r a t e w i t h i n a r o c k mass of which the peak s t r e n g t h has been e x c e e d e d . In a d d i t i o n , c o n t r o l l e d and p r e d i c t e d f a i l u r e i s a c c e p t a b l e i n m i n i n g w h i c h i s n o t the c a s e i n c i v i l c o n s t r u c t i o n . The t e m p o r a r y r e q u i r e m e n t s of mine o p e n i n g s a r e g e n e r a l l y not r e f l e c t e d w i t h i n the c o n f i n e s of c i v i l e n g i n e e r i n g . T h e s e f a c t o r s , p l u s the g e o m e t r i c a l and e x c a v a t i o n c o n s i d e r a t i o n s , r e q u i r e one to m o d i f y the e x i s t i n g system t h r o u g h the c o l l e c t i o n of e m p i r i c a l d a t a r e l e v a n t to open s t o p e d e s i g n . The m a j o r i t y of the c l a s s i f i c a t i o n s y s t e m s i n c l u d e , e i t h e r d i r e c t l y o r i n d i r e c t l y , an a s s e s s m e n t of the f o l l o w i n g p a r a m e t e r s , T a b l e 3 . 3 : - I n t a c t r o c k s t r e n g t h s ( u n c o n f i n e d c o m p r e s s i v e s t r e n g t h ) . I t i s a n e c e s s a r y p a r a m e t e r s i n c e i t forms the upper s t r e n g t h l i m i t of a r o c k mass which i s s u b s e q u e n t l y r e d u c e d due to r o c k d e f e c t s . - Rock q u a l i t y d e s i g n a t i o n (RQD). T h i s p a r a m e t e r i s an i n d i r e c t measure of f r a c t u r e f r e q u e n c y . I t i s a q u a n t i t a t i v e i n d e x based on a m o d i f i e d c o r e r e c o v e r y p r o c e d u r e . - S p a c i n g of d i s c o n t i n u i t i e s . 125 - C o n d i t i o n o f d i s c o n t i n u i t i e s . T h i s i n c l u d e s r o u g h n e s s , c o n t i n u i t y , s e p a r a t i o n , j o i n t w a l l w e a t h e r i n g a n d i n f i l l i n g . - G r o u n d w a t e r c o n d i t i o n s . T h i s i s a m e a s u r e o f i n f l o w r a t e s a n d w a t e r p r e s s u r e s . - S t r e s s f i e l d . T h i s r e f e r s t o t h e p r e v a i l i n g i n - s i t u s t r e s s e n v i r o n m e n t . Th e RMR s y s t e m was s e l e c t e d a s t h e v e h i c l e f o r s t o p e w a l l c h a r a c t e r i z a t i o n d u e t o i t s i n c o r p o r a t i o n o f t h e many v a r i a b l e s t h a t a r e c o n s i d e r e d t o i n f l u e n c e t h e b e h a v i o u r o f a r o c k m a s s . T h e i n t e r r e l a t i o n s h i p b e t w e e n t h e v a r i a b l e s a n d t h e c o n s t i t u t i v e e q u a t i o n s l i n k i n g t h e d i f f e r e n t v a r i a b l e s t o t h e r o c k mass b e h a v i o u r a r e c o m p l e x . T h e r e f o r e , a n a p p r o a c h was s e l e c t e d t h a t c o u l d be e m p i r i c a l l y c a l i b r a t e d t o t h e o p t i m u m s t o p e d e s i g n t h r o u g h o b s e r v e d r e s u l t a n t d i l u t i o n m e a s u r e m e n t s . T h e RMR s y s t e m was s e l e c t e d s i n c e : - O r i e n t a t i o n o f d i s c o n t i n u i t i e s . i t i n c o r p o r a t e s k e y p a r a m e t e r s a f f e c t i n g t h e r o c k mass b e h a v i o u r as d e f i n e d by t h e l i t e r a t u r e . - t h e s y s t e m i s s i m p l e t o e m p l o y a n d i s r e a d i l y 126 a p p l i c a b l e to e x i s t i n g methods of c o r e l o g g i n g and mapping t e c h n i q u e s as p r a c t i o c e d a t R u t t a n , T a b l e 5.1. T h i s i s p a r t i c u l a r l y i m p o r t a n t In r e l a t i n g h i s t o r i c c o r e l o g s i n terms of a r o c k mass number, s i n c e the l o g s g e n e r a l l y form the o n l y a v a i l a b l e d e s c r i p t o r f o r a p a r t i c u l a r s t o p e . T h i s i s due to e i t h e r l i m i t e d s t o p e w a l l a c c e s s a n d / o r the u n a v a i l a b i l i t y of d r i l l c o r e due to s a m p l i n g . The RMR system was employed i n i s o l a t e d a r e a s of the mine and was f o u n d to be a good p r e d i c t o r of mine b e h a v i o u r . A r e a s h a v i n g a low RMR r a t i n g were f o u n d to have problems w i t h : - d r a w p o i n t p l u g s due t o f a l l s of ground from the FW/HW and from the e x p o s e d benched back, F i g u r e 2.15. - e x c e s s i v e d i l u t i o n f r o m the FW/HW. - l a r g e amount of r e - d r i l l s . T h i s s t u d y w i l l be p a r t i c u l a r l y c o n c e r n e d w i t h q u a n t i f y i n g the RMR p a r a m e t e r i n terms of i t s e f f e c t on d i l u t i o n . Not a l l the p a r a m e t e r s shown i n T a b l e 3.3 a r e i n c o r p o r a t e d i n t o the RMR r a t i n g and t h e s e w i l l be d i s c u s s e d i n d i v i d u a l l y i n C h a p t e r 7, "Data B a s e " . The i n d i v i d u a l p a r a m e t e r s i n c o r p o r a t e d i n t o the RMR number w i l l be a s s e s s e d i n terms of t h e i r I n f l u e n c e on s t o p e d e s i g n . 5 . 2 . 1 G e o m e c h a n i c s C l a s s i f i c a t i o n (RMR) 127 A t h o r o u g h t r e a t i s e on the RMR system and on i t s a p p l i c a t i o n i s f o u n d i n A p p e n d i x I I . 5 . 3 R o c k Nass The d a t a base f o r t h i s s t u d y i s c o m p r i s e d of 54 s t o p e s and i s d i s t r i b u t e d as f o l l o w s : - 46 s t o p e s mined a t the time of c o m p l e t i o n of t h i s s t u d y of w hich 43 were s u i t a b l e f o r s u b s e q u e n t a n a l y s i s . - 8 a d d i t i o n a l s t o p e s mined s u b s e q u e n t to the c o m p l e t i o n of the s t u d y and w i l l be employed to r e i n f o r c e or d i s p r o v e the f o r m u l a t i n g e q u a t i o n . A d e t a i l e d s t r u c t u r a l i n v e s t i g a t i o n of the R u t t a n o p e r a t i o n was c o n d u c t e d by the a u t h o r i n o r d e r to i d e n t i f y domains w i t h p o t e n t i a l l y s i m i l a r g r o u n d b e h a v i o u r . T h i s , however, i s not c r i t i c a l to the f o r m u l a t i n g h y p o t h e s i s , s i n c e i n d i v i d u a l s t o p e s w i l l be r e l a t e d to o b s e r v e d d i l u t i o n upon e x t r a c t i o n . In terms of mine d e s i g n , i t i s i m p o r t a n t to i d e n t i f y a r e a s t h a t would e x h i b i t s i m i l a r r o c k mass b e h a v i o u r upon e x t r a c t i o n . T hese would e n a b l e a mine p l a n to be i m p l e m e n t e d . The c o n c e p t s of domain a n a l y s i s were employed ( B r a d y , 1 9 8 5 ) , however, i n d i v i d u a l s t o p e s were a t t r i b u t e d r o c k mass c h a r a c t e r i s t i c s and a n a l y z e d i n d i v i d u a l l y . The r e a d e r i s r e f e r r e d to a s t u d y c o n d u c t e d i n c o o p e r a t i o n w i t h the a u t h o r " D e t e r m i n a t i o n of S t r u c t u r a l Domains and S t r u c t u r a l D e s i g n S e c t o r s f o r the R u t t a n Mine", S e k i ( 1 9 8 4 ) . 128 H i s t o g r a m s have been d e v e l o p e d f o r the R u t t a n o p e r a t i o n e s t a b l i s h i n g the f o l l o w i n g p a r a m e t e r s f o r the h a n g i n g w a l l , f o o t w a l l , and o r e z o n e s : The i n t a c t r o c k s t r e n g t h s f o r the ma in g e o l o g i c a l u n i t s a t R u t t a n a r e shown i n T a b l e 5 . 2 . The above have been d e r i v e d f o r e a c h r o c k t y p e t h a t f o rms the i n d i v i d u a l c o n t a c t z o n e s . The r o c k mass i n f o r m a t i o n has been c o m p i l e d f r o m c o r e l o g s i n f o r m a t i o n and has been augmented by s t r u c t u r a l m a p p i n g . The d iamond d r i l l c o r e was AQ s i z e ( 2 7 m m ) . F i g u r e 5.1 i s a s t o p e c h a r a c t e r i z a t i o n p r o c e d u r e e m p l o y e d f o r a l l s t o p e s a t R u t t a n . A s t o p e i s c h a r a c t e r i z e d by two d r i l l h o l e s p e r s e c t i o n and two s e c t i o n s p e r s t o p e , F i g u r e 2 . 1 1 . In e s s e n c e , f o u r h o l e s a r e a n a l y z e d w h i c h a r e r e p r e s e n t a t i v e of the f o o t w a l l , o r e and h a n g i n g w a l l f o r a p a r t i c u l a r s t o p e . T h r e e m e t r e s of the i m m e d i a t e h a n g i n g w a l l and f o o t w a l l were e v a l u a t e d i n a d d i t i o n to the f u l l l e n g t h of the o re f o r a p a r t i c u l a r d r i l l h o l e . However , the r o c k q u a l i t y of the d r i l l c o r e w i t h i n two s t o p e d i a m e t e r s was s t u d i e d , but i n l e s s d e t a i l . M a j o r s t r u c t u r e s a r e r e c o r d e d i n . a d d i t i o n to the g e o m e t r y of the p r o p o s e d s t o p e and i t s c o n f i g u r a t i o n ( open g r o u n d ) a t the t ime of m i n i n g . The r o c k mass r a t i n g i s f u r t h e r g r o u p e d i n t o the f o l l o w i n g c l a s s e s : 129 C l a s s - 'Rock Mass R a t i n g A 31 - 100% B 6 1 - 8 0 % C . 4 1 - 6 0 % D 21 - 40% E 0 - 20% Through v i s u a l e s t i m a t e s and h i s t o r i c o b s e r v a t i o n , i t i s g e n e r a l l y a c c e p t e d t h a t w a l l s l o u g h a t R u t t a n i s p r i m a r i l y c o n f i n e d to the h a n g i n g w a l l . T h i s has been d e t e r m i n e d p r i m a r i l y t h r o u g h v i s u a l o b s e r v a t i o n a t the d r a w p o i n t s and the d r i l l l e v e l s . I t i s f o r t h i s r e a s o n , t h a t the r o c k q u a l i t y i n the v i c i n i t y of the h a n g i n g w a l l w i l l be employed i n c h a r a c t e r i z i n g an i n d i v i d u a l s t o p e . In c e r t a i n i n s t a n c e s , however, i t was f o u n d t h a t an a s s e s s m e n t of the f o o t w a l l was more c r i t i c a l when: - a major f a u l t i n t e r c e p t s the f o o t w a l l - the r o c k mass r a t i n g of the f o o t w a l l was much lower than t h a t of the h a n g i n g w a l l (one c l a s s or more d i f f e r e n c e ) A f u r t h e r p r a c t i c e was r e d u c i n g the Rock Mass R a t i n g by a s i n g l e c l a s s when a major s t r u c t u r e i n t e r c e p t e d e i t h e r of the w a l l c o n t a c t s . The RMR s y s t e m c l a s s i f i e s the mean r o c k mass p a r a m e t e r s . A major s t r u c t u r e must be t r e a t e d s e p a r a t e l y from the a d j a c e n t b o u n d i n g u n i t s . T h i s m o d i f i c a t i o n was shown to e m p i r i c a l l y be a good e s t i m a t o r of d i l u t i o n , C h a p t e r 7. I t i s 130 r e a l i z e d t h a t k i n e m a t i c a l l y e ach major s t r u c t u r e s h o u l d be a n a l y z e d i n g r e a t e r d e t a i l . However, f o r p u r p o s e s of t h i s i n v e s t i g a t i o n , i t was found t h a t by r e d u c i n g the RMR v a l u e by a c l a s s , r e s u l t e d i n s t a t i s t i c a l l y h i g h e r c o r r e l a t i o n s between the m o d i f i e d RMR and d i l u t i o n . The o r i e n t a t i o n of the i n d i v i d u a l s t r u c t u r e s was not i n c o r p o r a t e d i n t o the c l a s s i f i c a t i o n , s i n c e s t r u c t u r e s a t R u t t a n a r e g e n e r a l l y o r i e n t e d p a r a l l e l to the s t o p e c o n t a c t . The major d i f f e r e n c e i s fo u n d i n the f r e q u e n c y and s t r e n g t h of the i n d i v i d u a l j o i n t i n g . T h i s i s d e s c r i b e d i n d e t a i l i n s u b s e q u e n t c h a p t e r s . Groundwater was n ot i n c o r p o r a t e d i n t o the c h a r a c t e r i z a t i o n , F i g u r e 5.1. T h i s i s p r i m a r i l y due to the a b s e n c e °f water as e v i d e n c e d by d i p t e s t s c o n d u c t e d on the 430m, 370m, and 260m l e v e l . The c l o s e diamond d r i l l p a t t e r n g e n e r a l l y e n s u r e s t h a t any t r a p p e d g r o u n d w a t e r has an a c c e s s to d r a i n ( P a k a l n i s / G r o u n d w a t e r , 1986) . F i g u r e 5.2a,b,c show the d i s t r i b u t i o n of h a n g i n g w a l l , ore and f o o t w a l l r o c k u n i t s f o r the s t o p e s a t R u t t a n . The r o c k u n i t s can be g e n e r a l i z e d as f o l l o w s : 131 H a n g i n g W a l l and F o o t w a l l U n i t s C h l o r i t e T a l c S c h i s t (CTC) Q u a r t z i t e (QTZ) A c i d S e d i m e n t s (AS) B a s i c Dyke (BD) M a s s i v e S u l p h i d e (MS) Ore U n i t s S e m i - m a s s i v e S u l p h i d e w i t h S e m i - m a s s i v e S u l p h i d e w i t h S e m i - m a s s i v e S u l p h i d e w i t h S e m i - m a s s i v e S u l p h i d e w i t h M a s s i v e S u l p h i d e (MS) B a s i c Dyke (SMS-BD) Q u a r t z i t e (SMS-QTZ) C h l o r i t e T a l c S c h i s t (SMS-CTC) C h l o r i t e S c h i s t (SMS-SC) The d i s t r i b u t i o n i s d e l i n e a t e d f o r s t o p e s l o c a t e d i n the west and e a s t l e n s e s r e s p e c t i v e l y . The d i s t r i b u t i o n of r o c k mass p a r a m e t e r s f o r the immediate h a n g i n g w a l l c o n t a c t a r e summarized i n F i g u r e 5.3a,b and r e c o r d e d f o r the i n d i v i d u a l FW, ore and HW i n T a b l e 5.3. O n l y minor v a r i a t i o n s i n c l a s s i f i c a t i o n p a r a m e t e r s e x i s t e d when the i n d i v i d u a l r o c k u n i t s were s e p a r a t e d In terms of HW, ore or FW g i v e n the same r o c k type ( P a k a l n l s / R o c k M a s s , 1 9 8 5 ) . F i g u r e 5.4 shows the d i s t r i b u t i o n of RMR f o r the h a n g i n g w a l l of a l l s t o p e s a t R u t t a n . The e a s t l e n s e s g e n e r a l l y e x h i b i t h i g h e r RMR v a l u e s and a r e n o r m a l l y a s s o c i a t e d w i t h l o w e r s t o p e d i l u t i o n s . The a v e r a g e RMR r a t i n g s f o r the i n d i v i d u a l w a l l c o n t a c t s a r e as f o l l o w s : L o c a t i o n RMR ('%) F o o t w a l l ( 5 4 ) 5 8 + 1 8 0 r e ( 5 4 ) 6 3 + 1 7 Hanging W a l l ( 5 4 ) 60+ 19 132 F i g u r e 5.5 and 5.6 show t y p i c a l RMR s e c t i o n s and p l a n s f o r the R u t t a n o p e r a t i o n ( P aka l n i s / Rock. Mass,1985). 5.3.1 F a b r i c A n a l y s i s A d e t a i l e d l i n e mapping s u r v e y was c o n d u c t e d i n the v i c i n i t y of the I n d i v i d u a l l e n s e s . T h i s was s u p p l e m e n t e d by g e o l o g i c mapping c o n d u c t e d by R u t t a n g e o l o g i s t s . The i n f o r m a t i o n was c o m p i l e d onto l o w e r h e m i s p h e r e s t e r e o p l o t s y i e l d i n g the f o l l o w i n g o b s e r v a t i o n s : 1) T o t a l S t r u c t u r a l A n a l y s i s ( F i g u r e 5.7a) T h i s n e t encompasses a l l s t r u c t u r e s f o r a l l l e v e l s a t R u t t a n (6717 o b s e r v a t i o n s ) . T h r e e major s e t s were f o u n d t h r o u g h o u t the R u t t a n Mine: Most Dominant - J o i n t s e t p a r a l l e l to the o r e b o d y h a v i n g a s t r i k e of N 5 0 ° - 80° E and d i p p i n g 75° SE. M o d e r a t e l y Dominant - F l a t j o i n t s e t d i p p i n g a t 0 ° - 20° . M i n o r O c c u r r e n c e -- J o i n t s e t o r i e n t e d p e r p e n d i c u l a r to the o r ebody h a v i n g a s t r i k e of N0° - 30° E and d i p p i n g steeply(80° - 9 0 ° ) . 2) P l o t of F a u l t s The major s t r u c t u r e s a r e summarized below: a r e shown i n F i g u r e 2.7 and 5.6 and 133 N o r t h W a l l Shear ( t r e n d i n g N70°E, d i p 8 0 ° S ) A r t ' s F a u l t ( t r e n d i n g N45E, d i p 30°SE) E a s t Shear ( t r e n d i n g N10°W, d i p 8 5 - 9 0 ° E ) 3) F o o t w a l l , Ore, and H a n g i n g W a l l M i n i m a l s t r u c t u r a l i n f o r m a t i o n e x i s t s f o r the h a n g i n g w a l l , s i n c e most of the s t o p e d e v e l o p m e n t i s i n ore and f o o t w a l l r o c k s . In a d d i t i o n , the c o r e was not o r i e n t e d and c o n s e q u e n t l y makes j o i n t d i p d e t e r m i n a t i o n d i f f i c u l t . I s o l a t e d a r e a s where a c c e s s to h a n g i n g w a l l d r i v e s were p o s s i b l e i n d i c a t e d t h a t the h a n g i n g w a l l f a b r i c t y p i f i e d t h a t of the ore and the f o o t w a l l , F i g u r e 5.8. 4) Dykes and Q u a r t z V e i n s Dykes g e n e r a l l y t r e n d N 2 0 ° E and d i p 4 0 ° - 90°towards the SE. V e i n s t r e n d p a r a l l e l to the ore and p l u n g e 20 - 90 t o w a r d s the SE. 5) West and E a s t Ore L e n s e s No d i s t i n c t d i f f e r e n c e s e x i s t , however, f l a t t e r j o i n t s a r e more dominant i n the e a s t t h a n the west. S t e r e o n e t s f o r e ach ore l e n s were p r o d u c e d a t v a r i o u s l e v e l s , F i g u r e 5.9. F i g u r e 5.10 i s a p h o t o g r a p h i d e n t i f y i n g the m ajor d e s i g n s e t s which ar e summarized below: S e t 1: Most Dominant - N 5 0 - 8 0 0 E / 7 5 ° S E Set 2: M o d e r a t e O c c u r r e n c e - F l a t s t r u c t u r e 0 ° - 20°dip. Set 3: M i n o r O c c u r r e n c e - N 0 - 3 0 ° E / 8 0 ° - 9 0 ° S E . The c o n t i n u i t y of the s t u c t u r e was o b s e r v e d as e x c e e d i n g 200m and 100m r e s p e c t i v e l y f o r d e s i g n s e t one and two. D e s i g n s e t t h r e e was d i s j o i n t e d and c u t by s e t "one" , i t i s e s t i m a t e d to be l e s s than 15m i n l e n g t h . The c o n t i n u i t y was p r i m a r i l y r e c o r d e d from p i t mapping, F i g u r e 5.11. 134 5.4 K i n e m a t i c A n a l y s i s R e s i d u a l f r i c t i o n a n g l e s on saw-cut j o i n t s were p e r f o r m e d by Smith (1975) e m p l o y i n g d i r e c t s h e a r t e s t s on samples of q u a r t z - b i o t i t e - c h l o r i t e g n e i s s . The r e s u l t s i n d i c a t e d a o r e s i d u a l f r i c t i o n a n g l e of 29 based upon s i x s t a g e d s h e a r t e s t s . F i g u r e 5.12 shows an i s o m e t r i c o u t l i n i n g the p o t e n t i a l f o r f a i l u r e a l o n g the d e s i g n s e t s . E m p l o y i n g a s i m p i f i e d a n a l y s i s , as o u t l i n e d by Hoek and Bray (1977) and r e p r o d u c e d i n F i g u r e 5.13, i t i s shown t h a t t o p p l i n g f a i l u r e of the h a n g i n g w a l l i s p o s s i b l e . T h i s i s d e r i v e d from e m p l o y i n g a base (b) to b l o c k h e i g h t (h) r a t i o e q u i v a l e n t to a j o i n t s p a c i n g of 3m and a h e i g h t of 60m. The maximum j o i n t s p a c i n g a c c o r d i n g to F i g u r e 5.3b s h o u l d n o t e x c e e d t h r e e m e t e r s . The f o o t w a l l i s g e n e r a l l y more s t a b l e t h a n the h a n g i n g w a l l , howe y e r , a c o m b i n a t i o n of p l a n a r and t o p p l i n g f a i l u r e i s a p o s s i b i l i t y . A more r i g o r o u s s o l u t i o n I s p o s s i b l e , b u t i n the a u t h o r ' s o p i n i o n n ot w a r r a n t e d , s i n c e i t i s the p u r p o s e of t h i s s e c t i o n to o u t l i n e t h a t i n s t a b i l i t y due to s t r u c t u r e i s a p o s s i b l e f a i l u r e mechanism. S t e r e o n e t s of i n d i v i d u a l s t o p e s I n d i c a t e t h a t s t r u c t u r e s e x i s t w hich would g e n e r a l l y y i e l d f a i l u r e i n the f o o t w a l l as shown i n F i g u r e 5.14. J o i n t s e t . 3 i s c o n s i d e r e d to be a l a t e r a l r e l e a s e p l a n e f o r the f a i l u r e modes i n d i c a t e d i n F i g u r e 5.14. T h i s was a l s o the o b s e r v e d method of s l o u g h f o r the m a j o r i t y of s t o p e s at R u t t a n ( P a k a l n i s / B a c k - A n a l y s i s of Stope 135 F a i l u r e s , 1984) . T o p p l i n g or s l a b b i n g from the h a n g i n g w a l l i s g e n e r a l l y the o b s e r v e d method of i n s t a b i l i t y a t R u t t a n . The p a r t i n g i s a l o n g a f o l i a t i o n or j o i n t s u r f a c e t h a t p a r a l l e l s the ore l e n s . The o b s e r v e d f a i l u r e mode i s s i m u l a t e d by F i g u r e 5.15. T h i s i s a base f r i c t i o n model of which the d i m e n s i o n s and f a i l u r e g e ometry t y p i f i e s the o b s e r v e d c o n d i t i o n s f o r s t o p e s a t R u t t a n . 5.5 O b s e r v a t i o n s / C o n c l u s i o n s T h i s c h a p t e r summarizes the c h a r a c t e r i s t i c s of the r o c k f a b r i c i d e n t i f y i n g the p o s s i b l e f a i l u r e modes. S t r u c t u r a l I n s t a b i l i t y i s e v i d e n t t h r o u g h t o p p l i n g on j o i n t s s e t s p a r a l l e l i n g the s t o p e c o n t a c t and r e s t i n g on f l a t c r o s s - c u t t i n g j o i n t s . F u r t h e r i n v e s t i g a t i o n s w i l l be b a s e d upon the c o n c l u s i o n t h a t : - the h a n g i n g r e l a x e d s t a t e - f a i l u r e due w a l l and f o o t w a l l f o r a par to s t r u c t u r a l i n s t a b i l i t y i t i c u l a r s t o p e i s i n a s a p o s s i b l e mechanism 136 T a b l e 5.1: C o r e L o g g i n g Format - R u t t a n Quart* - Q Plafloclase - P Orthoclase • CC Chlorite - CH B i c t l t e - fii Sericite - SR Talc - TC Hornblende • g Carbonate - CA Epldote - EP Cordiexite - CD Andaluslte - AD Staurolite • ST Garnet - cr T r c o D l l u - TR Actlnol i te - AC Anhydrite - AN Apatite • AP Gypsio • lbgnatlT* . MC Galena - GA Pyrite • PY Prynotite - PO OaalcopyTita - CPT Sphalerite • SPH Footwill Volcanlcloatlcs -TV Basic Sediments «6S Intermediate Sediments - IS Acid Sediments Rhyolite •flHY Dacite Andeslte «AJ( Dior i te "©I Granite -GR Chert K31 Altered FW-Volcaniclastic-tfV Granodnrite Spotted United Brum Eyes Quartzite Chlorite Schist B i o t i t e Schist Ser ic i te Schist Basic Dyke Acid Dyke Quartxview Lost Core Sqnimasaive ^ i f l r t t t Uassive Sulfide Chlorite Talc Schist Quartzite - Chlorite Quartlite - Ser ic i te Quartzite - B io t i t e Trenollte Schist Granite with IS Granite with BS Granite with AS •CKD -SU •QZ -SC -AD -37 -as -rse MIME twrr Utexed Ft Volcaniclastlce-AV Quartzite -qz Diori te -DI Granite K B E r t a l l t e -EX HW Sediments -HITS Mineralised Chlor i te Schist tOC Fine - r Medium - 11 Coarse - C Granular — G Blebby - B Viens - V INTENSITY DESCRIPTCRS None - H Weak - V Moderate - If Strong - S Excessive - E GENERAL TEXTURE DESCRD7ICRS Schistose - S Uasslve - M Gnessic - G TECIFIC TEXTURE DESCRIPTCRS Breccia - X Porpbyrobiastic - B C la s t i c - c Porpnyritic - P SECONDARY STRUCTURE Banded - B Folded - F Faulted • L Shear - S • TWeil jMM . Cw>l<»cm " i j H i n l . M i * . O-lScn • j) Ve/r iftiMjr M M fl-)CT • j) This*!/ lamna!i. CO.J-ltta m l) 0-10" lo-ao" 20-30" 30-W" 40-50" SO-60" 60-70" 70-80" LICK 0 1-2 " - 1 2-3 " _ 2 3-4 '• 3 4-5 " - 4 5-6 '• • 5 6-7 " 6 7-8 " - 7 8-9 " 8 9-10" - 9 JOBER OF BRUtfS PER 10 nZT CEDE 0-5 5-10 10-20 20-30 30-40 40-50 • 1 50-60 - « 60-70 - 7 70-80 - 8 >£0 - 9 O l d Format ( P r i o r 1983) • Q Pltuflocluse - P Drr.hoclase -OC Chlorite - CH Bio ' l fe - BI Serlclre - SR Talc - TC Ftornblende - H Cartonare - CA Epidore - EP Cordierlre - CD Andaluslre - AD Sfaurollre - ST Garnet - GT TramUre - TR Acrlnoi i 'e - tc An&ydrlte - AN Apat.ire • AP Gypsixa . - GY Magnetite - JIG Galena * GA Pyrire - PY Pryho t i re • PO Chaleopyrite - CPY Sphalerite * SPH ROCK TYPE MINE U*TT footwall Volcanlclasri.cs Basic Sediments Intermediate Sediments Acid Sediments RByoUre D»eire Andes! re Basalt Dtorl re Brwiire Chert Alrered Fi-Colcanlclasttc Granodnrlre Sported United Brown Eyes *uurT .zlte Chlorlre Schist Blotite Schist Sericite Schist Basic Dyke Acid Dyke Quartzview Lost Core Seeflmasslve Sulf i te Massive Sulfide Chlorlre Talc Schist Quarrzire - Chlorite Quarrzire - Ser ic lre Quirtzire - Blorire Trerolire Schist Granire *-lth IS Gram re wirh BS Granire udrti AS Altered FW Volciuitclaarlcs - AV Quarrzire - QZ Diorire - DI Granlre - GR ExhallTe - EX t* Sedlmenrs - MS Ulnerallzed Chlorlre Schist - JSC PRI3.1ARY STRLCTtRE Rock Tualiry Deslpjiarlon (flfj)) 9U - luo; 5 75 - • 4 50 - 7 K • 3 25 - so: - 2 0 - 251 - 1 RJ> - I Solid 7 10 c to ta l (measure centre ro cenrn Record under Prljmry Structure MISBtAL DESCRIPTICHS Fine UedluB Coarse Granular Blebby Viens IVTP5ITY DESCRIPIORS None Weak - * Moderate - u SrronR - s Excessi^-e - E GENERAL TEXTURE DESCRIPTORS . Schistose llassive Gnessic SPECIFIC TEXTURE DESCRIPTORS BreccU Porphyrob1ast1c SEEPEDARY STRLCTTRE Bttntled Folded Faulted Shear 3 0 - 3 0 " 3 0 - 4 0 * 40 • SO-SO - 608 6 0 - 7 0 * 70 - 80" 80-911* TEXTLRAL MINERAL SIZE UCM - 0 1- 2 UCM - 1 2- 3 UCM - 2 3- 4 UQI - 3 4- 5 LI CM - 4 5- 6 UCM - 5 6- 7 UCM - 6 7- 8 UCM - 7 8- 9 UCM - 8 9- 10 UCM - 9 0 - 1 - 0 2 - 3 - 1 4 - 6 - 2 7 - 1 0 - 3 1 1 - 2 0 - 4 2 1 - 4 0 - 3 New Format ( P o s t 1983) P o i n t Load S t r e n g t h V a l u e s R e c o r d e d on B o t h F o r m a t s 137 Table 5.2: I n t a c t Rock Strength Parameters Rock Type Uniaxial Compressive Strength (MPa) Poisson's Ratio Modulus of Deformation (GPa) 1 Number 1 of Samples ' Semi-Massive Sulphide-Chl o r l t e 70 ± 24 0.23 t 0.05 66 i 19 13 Massive Sulphide 89 ± 37 0.2 ± 0.08 88 ± 37 39 Basic Dyke Z02 i ee 0.2 ± 0.07 81 1 14 10 Acid Seds. 135 ± 43 0.19 ± 0.07 77 ± 19 e Quartzltes 113 ± 49 0.12 ± 0.06 54 i 23 A ! . 1 Chlorite Schists 49 ± 11 0.34 ± 0.12 50 t 17 14 Chlorite Talc Schists 25 ± 14 0.33 ± 0.09 39 ± 9 • " i Table 5.3: Summary of Rock Mass Parameters ROCK TYPE OBSERVATIONS 1 5 5 0 * RQD(%) SPACING (m) FW Ore HW CTC(7) 5 2 <1 25t 8 .16-* .2 SC(31) 17 - 14 2 . 1 ± 1.1 47 i 19 .97* .7 QTZ(34) 16 - 18 4.8 * 1.9 69 • 18 1.4 * .8 AS(8) 1 - 7 3.9 i 1.8 68 ± 22 1.2 * .7 BD(6) 3 - 3 5.3 £ 2.6 70 * 20 1.1 * .7 MS(63) 12 41 10 2.9 i .9 8 2 * 10 1 . 7 * .8 SMS-SC(9) - 9 - 1.6 i .6 48 * 13 . 8 8 s .7 SMS-BD(l) - 1 - 6.0 68 1.3 SMS-QTZ(l) - 1 - 3.0 70 1.6 SMS-CTC(2) - 2 - 1.5 • 1. 44 * 24 .3 t .3 (54) (54) (54) * Unconflned C o m p r e s s i v e S t r e n g t h I s 5 0 x 24 ( S m i t h , ** R e f e r s t o Number of Stope W a l l s A f f e c t e d ( ) Sample S i z e STOPE• CLASSIFICATION F6RAMETERS ANO THFJR RATNGS PARAMETER RANGE OF VALUES itreygih port tood > 8 MPo 4-8 MPo 2-4 MPo 1-2 MPa lor lowranoe.uci W cefc»«d 1 mocifoci llrftalh >200 MPo 00-200 MPo 50-00 MPo 25-50 MPo 10-25 3-10 I-roiinq IS 12 7 4 2 1 0 *icorequ<*lytRQO 90-100 V . 75-90 V . 50-75 • / . 25-50 • / . <25 • »Ottna 20 17 13 8 J 3 > 3m 1-3 m 0.3-lm 50- 300mm < 50 mm rating 30 25 20 10 5 4 condition of jotnit vfough.ndCDnl. nosepor. til rwah ftxt Kpor *lirn* Ivd jnwotrock 1 (ouoh u l . upor *lmm lllfvwal ro * jJV gouge < 5mmtjft open l-5mm,carttjri 111 gcuoe>5mm |n open ^Sflvn cant jn 20 12 6 9 ROCK MASS RATING FC I0TWALL O R E HANGING WALL STRENGTH R O D . SPACING CONDITION TOTAL MAJOR STRUC. COMMENT ROCK T Y P E H O L E NUMBER SECTION ?! t* 1* i i i X 2 * t i CLASSIFY ISOLATEO . RIB ECHELON _ DIMENSIONS LEVEL SPAN WIOTH HEIGHT: _ BLASTING: . EXCAV. RATE (iCOOm Vmrh) VOLUME, m J 10,000 | 20.000 | OPEN GROUND (sketch/fill) RATING F.VK ORE F i g u r e 5.1: S t o p e C h a r a c t e r i z a t i o n HRNCTNC HRLL ROCK TTPCS CBST (23 Stop.*) I Stop..) BOTH (34 Stop..) rOOTWflU. ROCK TYPCS S \ \ [ 7 V CAST (23 Stop..) WEST (31 Stop..) BOTH (54 Stop..) CTC SC QTZ I - H . rttt sns-OTZ CBST (13 Stop..) MCST (It Stop..) BOTH (34 Stop..) F i g u r e 5 . 2 : D i s t r i b u t i o n o f Rock T y p e s POINT LOflO STRCNCTH INDCX Urn) IB8 35 38 as 18 73 78 S3 ca S3 38 13 48 33 38 JS 28 IS 18 S 8 n m X x X K x X X X X X X X X X J t x h X ?-< 2-4 np» i 1-2 npi CTC HRNCINC MRLL ROCK QUALITY OCSICNP.TOR (ROD) 38-18SX S8-7S)t HRNCINC HRLL F i g u r e 5 . 3 a : H a n g i n g W a l l Rock is s P a r a m e t e r s JOINT SPRCINC CTE SC QTZ r] hp rl-i r r r r r r 4f BO B.3-l» <9>ca KflNGINC HflLL CONDITION CTS SC QTZ HS BO ns Rgh/Hd Hod Rgo>VM nod Rah/Eft SI IcksCoug* Gauge/Fault Figure 5 . 3 b : Hanging Wall Rock Mass Parameters 142 STOPC ROCK HASS RATING 188 35 . 38 . as . SB 75 . 78 . S3 . c a . 55 . 38 . 15 . 18 . 35 . 38 . 25 . 28 . IS . 18 J 71% 1 17% v. X \ 7 53% * 16% N. 60% i 19% / 2^s CBST 123 Stop..) HCST (31 Stop..) BOTH (34 Stop..) HHNCINC HALL B i e i - i a a x B:61-88X Ci41-S8)C Di2t-4BX F i g u r e 5.4: Rock Hass D i s t r i b u t i o n 143 F i g u r e 5.6a: T y p i c a l RMR Plan - 240m Level F i g u r e 5 . 6 b : T y p i c a l *MR P l a n - 370m L e v e l F i g u r e 5.7: T o t a l S t r u c t u r e s a t R u t t a n (6717 o b s ) W 4 F o o t w a l l ( 33 o b s ) H a n g i n g H a l l (22 obs) Ore (855 o b s ) F i g u r e 5.8: J o i n t i n g / F o l i a t i o n f o r "C L e n s " on 260m L e v e l B260(893 OBS) C260(855 OBS) F260(690 OBS) H260(656 OBS) J 2 6 0 ( 7 8 9 OBS) C320(745 OBS) F320(286 OBS) H320(396 OBS) J K 3 2 0 ( 7 4 5 OBS) D400(245 OBS) F400(55 OBS) TB+30 D430(182 OBS) 6-10% Contour 0- 5% Contour F i g u r e 5.9: P o l e C o n c e n t r a t i o n s I n c l u d i n g F o l i a t i o n and J o i n t i n g ( i e . "C320" R e f e r s t o "C L e n s " on 320m L e v e l ) F i g u r e 5.10: P h o t o g r a p h I d e n t i f y i n g t h e M a j o r S e t s a t R u t t a n F i g u r e 5.11: Photographs Showing the C o n t i n u i t y of S t r u c t u r e 150 F i g u r e 5.12: D e s i g n S e t s F i g u r e 5.12b: S c h e m a t i c ( s e c t i o n ) I d e n t i f y i n g D e s i g n S e t "1 & 2" 151 0 10 20 M "0 W 60 '0 8 0 9 0 Base plane angle i> - degrees F i g u r e 5.13: C o n d i t i o n s f o r S l i d i n g and T o p p l i n g o f a B l o c k on an I n c l i n e d P l a n e (Hoek and B r a y , 1977) ORE L E N S E S B ,,-t S E T 3 BENCH -130 - t " f S E T 3 \ V \ <S-S E T I 9 - e = 2 9 ° / ' S E T 2 ;-\ -r": O P O T E N T I A L W E D G E S SCHMIDT MET F i g u r e 5.14: S t e r e o n e t Showing the P o t e n t i a l f o r F a i l u r e i n the FW of the "B L e n s e s " on t h e 430m L e v e l 152 F i g u r e 5.15: Base F r i c t i o n M o del 153 CHAPTER SIX DILUTION 6.1 I n t r o d u c t i o n T h i s p a r a m e t e r i s a m e a s u r e o f t h e q u a l i t y o f t h e s t o p e d e s i g n . V a r i o u s d e f i n i t i o n s e x i s t , h o w e v e r , i t i s a p a r a m e t e r r e c o r d e d b y m o s t o p e n s t o p e o p e r a t o r s , C h a p t e r 3 . 4 . 3 . D i l u t i o n w i l l be c o n s i d e r e d a s t h e d e p e n d e n t c o n t r o l v a r i a b l e . T h e s i g n i f i c a n c e o f t h e I n d i v i d u a l s t o p e c h a r a c t e r i s t i c s w i l l be e v a l u a t e d e m p i r i c a l l y i n t e r m s o f d i l u t i o n . D i l u t i o n f i g u r e s f r o m f o r t y - t h r e e s t o p e s w i l l b e a n a l y z e d a t v a r i o u s s t a g e s o f e x t r a c t i o n y i e l d i n g 432 d i l u t i o n v a l u e s . T h e s e v a l u e s a r e s u b s e q u e n t l y a v e r a g e d i n t o 133 o b s e r v a t i o n s . 6.2 D e f i n i t i o n V a r i o u s d e f i n i t i o n s e x i s t a s i n d i c a t e d i n C h a p t e r 3 . 4 . 3 . D i l u t i o n h a s a d i r e c t a f f e c t o n p r o f i t a b i l i t y ( K e r s t e n , 1 9 8 3 ) a n d s t o p e s c h e d u l i n g . T h e c a l c u l a t i o n o f a d i l u t e d g e o l o g i c a l o r e r e s e r v e a t R u t t a n h a s b e e n h i s t o r i c a l l y d e t e r m i n e d i n t h e f o l l o w i n g m a n n e r . As e a c h m i n i n g b l o c k i s d e f i n e d , a c e r t a i n a m o u n t o f d i l u t i o n i s a t t r i b u t e d t o t h e b l o c k , t h i s b e i n g o n e m e t e r o f t h e f o o t w a l l a n d 1.8 m e t e r s i n t h e h a n g i n g w a l l 154 ( h i s t o r i c m e t h o d ) . These numbers have no t h e o r e t i c a l b a s i s , but r e f l e c t the f a c t t h a t b e c a u s e of the 70 d e g r e e d i p of the o r e b o d y , most of the d i l u t i o n i s a t t r i b u t e d t o the h a n g i n g w a l l . T h i s w i d t h of d i l u t i o n d i v i d e d by the w i d t h of the ore r e s e r v e b l o c k g i v e s a volume p e r c e n t a g e of d i l u t i o n . T h i s v a l u e i s t h e n c o n v e r t e d to t o n n e s d i l u t i o n w h i c h when d i v i d e d by i n - s i t u t o n n e s o f ore f o r the b l o c k , g i v e s a w e i g h t p e r c e n t a g e of d i l u t i o n . T h i s w e i g h t p e r c e n t e x t e r n a l d i l u t i o n i s then combined w i t h o t h e r b l o c k s f o r m i n g the r e s e r v e f o r a g i v e n s t o p e and an a v e r a g e w e i g h t p e r c e n t d i l u t i o n i s then d e t e r m i n e d . C o n s e q u e n t l y , p r i o r to m i n i n g , one has an e s t i m a t e d d i l u t i o n a t t r i b u t e d to e a c h s t o p e . At the end of the s t o p e l i f e , an a c t u a l d i l u t i o n f i g u r e b ased on the h i s t o r y of m i n i n g of t h a t s t o p e i s r e q u i r e d i n o r d e r to p r o p e r l y r e c o n c i l e I t back to the o r i g i n a l o re r e s e r v e . T h i s i s a c h i e v e d by v i s u a l o b s e r v a t i o n of e a c h p r o d u c i n g s t o p e on a d a i l y b a s i s by grade c o n t r o l g e o l o g i s t s . A v i s u a l I n t e r p r e t a t i o n of the volume p e r c e n t a g e of m a s s i v e s u l f i d e , s e m i - m a s s i v e s u l f i d e , d i s s e m i n a t e d m a t e r i a l and d i l u t i o n b a s e d on i r o n c o n t e n t i s made f o r each p r o d u c i n g d r a w p o i n t . D i l u t i o n i s c l a s s i f i e d as a n y t h i n g w i t h l e s s than 10% i r o n or l e s s than one p e r c e n t c o p p e r . I t can be c l a s s i f i e d as e i t h e r i n t e r n a l or e x t e r n a l to the ore r e s e r v e . Based on p r i o r knowledge of the r o c k t y p e s i n h e r e n t to a p a r t i c u l a r s t o p e , the s i z e of muck a n d / o r the p r e s e n c e of b l a s t h o l e s w i t h i n the muck, the g e o l o g i s t can e s t i m a t e what p e r c e n t a g e of 155 the d i l u t i o n i s i n t e r n a l or e x t e r n a l . These v i s u a l e s t i m a t i o n s a r e c o m p i l e d a t the end of e a c h month and a t o t a l a v e r a g e d i l u t i o n f i g u r e f o r i n t e r n a l and e x t e r n a l d i l u t i o n i s d e r i v e d . The e x t e r n a l d i l u t i o n i s c o n v e r t e d to a w e i g h t p e r c e n t as f o l l o w s : D i l u t i o n Weight % = ( D i l u t i o n Volume % x Tonnage F a c t o r f o r Ore/Tonnage F a c t o r f o r W a s t e ) / ( 1 0 0 - D i l u t i o n Volume % x Tonnage F a c t o r f o r Ore/Tonnage F a c t o r f o r Waste) An a v e r a g e w e i g h t p e r c e n t f o r the e x t e r n a l d i l u t i o n i s d e t e r m i n e d f o r a p a r t i c u l a r s t o p e l i f e . T h i s e n a b l e s the g e o l o g i s t to r e c o n c i l e back to the o r i g i n a l e s t i m a t e d r e s e r v e to d e t e r m i n e the a c c u r a c y of the o r i g i n a l o r e r e s e r v e e s t i m a t i o n and t h e r e f o r e d e t e r m i n e s u b s e q u e n t m i n i n g l o s s e s . T h i s method has been employed a t R u t t a n s i n c e 1979. The " r u l e of thumb" q u a n t i t y of lm and 1.8m of w a l l s l o u g h i s employed i r r e s p e c t i v e of d e p t h , r o c k q u a l i t y , s t o p e c o n f i g u r a t i o n or s t o p e w i d t h . The d i l u t i o n , as e s t i m a t e d i n terms of ore r e s e r v e w e i g h t , e n a b l e s the o p e r a t o r to q u i c k l y a s s e s s the amount of m a t e r i a l mined e x t e r n a l to the o r e . I t i s a more m e a n i n g f u l v a l u e than a volume d i l u t i o n i n t h a t the v a r i a b i l i t y of o r e d e n s i t y i s i n c o r p o r a t e d i n t o the d e f i n i t i o n . T h i s d e f i n i t i o n w i l l be employed f o r p u r p o s e s of t h i s s t u d y . I t i s i m p o r t a n t to comment on the a c c u r a c y of the p r o c e d u r e . D i l u t i o n i s an o b s e r v e d p a r a m e t e r t h a t has been r e c o r d e d i n most i n s t a n c e s on a d a i l y b a s i s f o r e a c h d r a w p o i n t . 156 The f r e q u e n c y of o b s e r v a t i o n and the c o n s i s t a n c y of measurement has p r o d u c e d a f i g u r e t h a t i s a r e l i a b l e measure of the waste tonnage t h a t comes from a p a r t i c u l a r s t o p e . In a d d i t i o n to the d i l u t i o n b e i n g o b s e r v e d , the c o p p e r and z i n c g r a d e s a r e e s t i m a t e d on a m o n t h l y b a s i s f o r e a c h p r o d u c i n g s t o p e . They a r e d e t e r m i n e d from g r a b s a m p l e s , d r i l l h o l e a s s a y s and from the o b s e r v e d d i l u t i o n . The o b s e r v e d g r a d e s were f o u n d to be h i s t o r i c a l l y w i t h i n 3% of m i l l e d grade (1979 - p r e s e n t ) . D i l u t i o n e v a l u a t e d s o l e l y on a grade b a s i s would y i e l d : D i l u t i o n (%) = (Go - Gm)/(Gm - Gd) where: Go - i s the g r a d e of u n d i l u t e d o r e Gm - i s the g r a d e of tonnage m i l l e d Gd - i s the g r a d e of d i l u t i o n The p r o b l e m a s s o c i a t e d w i t h t h i s method i s i n d e t e r m i n i n g the v a l u e "Go and Gd". P r e s e n t l y work i s b e i n g c o n d u c t e d i n b e t t e r e s t i m a t i n g the two g r a d e s on a m o n t h l y b a s i s and r e l a t i n g the v a l u e to the o b s e r v e d d i l u t i o n . In a d d i t i o n , s o n i c p r o b e s a r e b e i n g d e v e l o p e d by Ruttan/UBC i n e n a b l i n g the o p e r a t o r to p r o f i l e the v o i d c r e a t e d . I t i s assumed t h a t the a c c u r a c y of g r a d e o b s e r v a t i o n e x t e n d s to t h a t of d i l u t i o n e s t i m a t i o n s i n c e one has an e f f e c t on the o t h e r . However, the d i l u t i o n a p p r o a c h a t R u t t a n i s v a l i d f o r R u t t a n and the a b s o l u t e ' v a l u e s must be c a l i b r a t e d f o r o t h e r o p e r a t i o n s i n t e n d i n g to employ t h i s m e t h o d o l o g y towards s t o p e d e s i g n . 157 6.3 Observed D i l u t i o n The f o l l o w i n g o u t l i n e s the method employed i n d e t e r m i n i n g the r e s u l t a n t d i l u t i o n a t v a r i o u s s t a g e s of s t o p e e x t r a c t i o n . As m e n t i o n e d , the o b s e r v e d d i l u t i o n i s a measure of the e x t e r n a l waste f o r a p a r t i c u l a r s t o p e and can be d e f i n e d as shown i n F i g u r e 6.1. D i l u t i o n measurements a r e r e c o r d e d d a i l y and t a b u l a t e d m o n t h l y as i n d i c a t e d p r e v i o u s l y . T h i s i s s u b s e q u e n t l y c o n v e r t e d by the a u t h o r i n t o a g i v e n volume of s t o p e e x c a v a t i o n e x h i b i t i n g a p a r t i c u l a r l e v e l of d i l u t i o n . M o n t h l y t a b u l a t i o n s a r e made and p l o t t e d as shown i n F i g u r e 6.2 f o r a p a r t i c u l a r s t o p e . The c u m u l a t i v e d i l u t i o n i s r e c o r d e d v e r s u s the volume e x t r a c t e d . T h i s volume e x c a v a t e d i s d e t e r m i n e d t h r o u g h r e c o r d i n g the trammed t o n n e s f o r a p a r t i c u l a r s t o p e . The volume drawn i s r e l a t e d to the volume e x c a v a t e d s i n c e i t i s g e n e r a l p r a c t i c e a t R u t t a n to : - muck e v e n l y from a l l d r a w p o i n t s . T h i s i s r e q u i r e d i n o r d e r t o e n s u r e t h a t the d i l u t i o n i s e v e n l y d i s t r i b u t e d , i e . the d i l u t i o n v a l u e s r e c o r d e d a r e r e p r e s e n t a t i v e f o r the v o i d m i n e d . By s h u t t i n g down a d r a w p o i n t , one would b i a s the d i l u t i o n e s t i m a t e s . - muck a l l s t o p e s u n t i l empty, t h e r e b y e n s u r i n g a f r e e - f a c e f o r the s u b s e q u e n t b l a s t . N o r m a l l y a maximum l a g time 1 5 8 between to n n e s b l a s t e d and mucked i s two months. The u n d e r c u t may be f u l l , t h e r e f o r e the b l a s t e d r e s e r v e s may n o t e x a c t l y be r e l a t e d to the d i l u t i o n s d e t e r m i n e d f o r the to n n e s trammed. The volume a s s o c i a t e d w i t h the r e s u l t a n t d i l u t i o n was e s t i m a t e d i n t h i s manner r a t h e r t h a n e m p l o y i n g b l a s t e d r e s e r v e s , i n t h a t the d i l u t i o n e s t i m a t e i s d i r e c t l y r e l a t e d to the tonnes drawn a n d / o r the v o i d c r e a t e d . I t i s not n e c e s s a r i l y r e l a t e d to the t o n n e s b l a s t e d e s p e c i a l l y i f n o t a l l the b l a s t e d r e s e r v e s have been trammed. The i n c r e m e n t a l d i l u t i o n (%) i s a measure of the amount of w a l l s l o u g h o v e r an i n c r e m e n t of e x c a v a t e d volume. F i g u r e 6.2 d e p i c t s the r e s u l t a n t i n c r e m e n t a l d i l u t i o n f o r s u c c e s s i v e m i n i n g i n t e r v a l s t h a t a r e e q u i v a l e n t to 10% of the t o t a l s t o p e r e s e r v e volume. I t g r a p h i c a l l y shows t h a t as the s t o p e i s i n i t i a l l y e x c a v a t e d , i e . f i r s t 10% of o r e volume removed, the d i l u t i o n i s low. However, when the s t o p e i s a l m o s t c o m p l e t e l y e x c a v a t e d ( 8 0 % ) , f o r an a d d i t i o n a l 10% of s t o p e volume r e m o v a l , the d i l u t i o n a s s o c i a t e d w i t h t h a t 10% volume has i n c r e a s e d to 16% . T h i s i n c r e m e n t a l d i l u t i o n w i l l be employed s u b s e q u e n t l y i n e s t i m a t i n g b l a s t i n d u c e d damage, e r r o r In e s t i m a t i o n and o t h e r f a c t o r s t h a t a r e d i f f i c u l t to q u a n t i f y . 6.3.1 Volume Trammed V e r s u s S t o p e D i m e n s i o n s Mined 159 Stope span was d e t e r m i n e d by e m p l o y i n g e i t h e r of two methods: Method 1: Average span r e c o r d e d from s t o p e l o n g i t u d i n a l s , F i g u r e 6.4. Method 2: A v e r a g e span b a c k - c a l c u l a t e d from the volume trammed, F i g u r e 6.5, whereby: I n f e r r e d Span = (Volume T r a m m e d ) / ( V e r t i c a l Stope H e i g h t x A p p a r e n t Stope W i d t h ) , F i g u r e 6.5. G e n e r a l l y , when i n t e r m e d i a t e l e v e l s a r e employed, the s t o p e was b l a s t e d f o r the f u l l s t o p e h e i g h t and w i d t h , F i g u r e 2.15. P r i o r t o J a n u a r y , 1983, ITH s t o p e s were b e n c h e d , F i g u r e 2.16, where a f t e r t h e y were b l a s t e d f o r the f u l l s t o p e h e i g h t . Method 2 would be a poor a p p r o x i m a t i o n f o r benched s t o p e s . I t i s t r u e t h a t the benched s t o p e s were b l a s t e d f o r the f u l l s t o p e w i d t h , however the s t o p e h e i g h t was v a r i a b l e . In e m p l o y i n g method 2, c a l c u l a t i o n of the span would be u n d e r e s t i m a t i n g the t r u e span by e m p l o y i n g the f i n a l s t o p e h e i g h t . T h i s a f f e c t e d e i g h t (8) s t o p e s i n our d a t a base of f o r t y - t h r e e ( 4 3 ) . The s t o p e e x t r a c t i o n p r o f i l e c o u l d n o t be r e p r o d u c e d f o r t h e s e s t o p e s p r i o r to 1983. These s t o p e s were i n c l u d e d w i t h i n the d a t a base by r e c o r d i n g s o l e l y the f i n a l s t o p e geometry and the r e s u l t a n t o v e r a l l d i l u t i o n . 160 Figure 6.2: Cumulative D i l u t i o n VS Volume Excavated 161 - L ILL. I 1 1 A.;:i;-. ; — / Figure 6 . 3 : Volume Trammed = LI x tf x H 12 II 8_ 7 10 12 13 F i g u r e 6 . 4 : L o n g i t u d i n a l Showing A T y p i c a l E x t r a c t i o n Seq uence 162 F i g u r e 6.5: I n f e r r e d Measurement o f S t o p e Span where: S t o p e Volume = H x W x L Stope Volume = H' x V x L H' = A p p a r e n t S t o p e H e i g h t i n P l a n e o f H a n g i n g H a l l H = True S t o p e W i d t h L = Stope Span W' = A p p a r e n t S t o p e W i d t h Measured i n H o r i z o n t a l P l a n H = V e r t i c a l S t o p e H e i g h t 163 CHAPTER SEVEN DATA BASE 7.1 I n t r o d u c t i o n T h i s c h a p t e r i d e n t i f i e s the most c r i t i c a l p a r a m e t e r s as d e t e r m i n e d t h r o u g h s i n g l e and m u l t i v a r i a t e s t a t i s t i c a l a n a l y s i s . T r e n d s u r f a c e a n a l y s i s has been u s e d to summar i ze d a t a t h a t i s t oo numerous to be g r a s p e d r e a d i l y by e y e . L i n e a r c o r r e l a t i o n s be tween v a r i a b l e s as d e f i n e d by S p i e g e l , 1972 were e m p l o y e d i n i t i a l l y to d e t e r m i n e the r e l a t i o n s h i p be tween the most c r i t i c a l p a r a m e t e r s i n o r d e r to f o r m u l a t e a g o v e r n i n g e m p i r i c a l r e l a t i o n s h i p . A s e c t i o n d e s c r i b i n g the s t a t i s t i c a l t e c h n i q u e i s b r i e f l y p r e s e n t e d w h i c h w i l l o u t l i n e t he g e n e r a l c o n c e p t s e m p l o y e d i n a r r i v i n g a t a s t a t i s t i c a l l y s i g n i f i c a n t r e l a t i o n s h i p . The i d e n t i f i c a t i o n of the p a r a m e t e r s f o r m u l a t i n g the d a t a ba se a r e r e p r o d u c e d , w h i c h w i l l be s u b s e q u e n t l y a n a l y z e d i n d e t e r m i n i n g the most c r i t i c a l p a r a m e t e r s i n te rms of t h e i r e f f e c t on d i l u t i o n . The b l a s t c o r r e c t i o n f a c t o r w i l l be d i s c u s s e d i n d e t a i l s i n c e i t f o rms an a l l e n c o m p a s s i n g term w h i c h w i l l p a r t l y c o m p e n s a t e f o r r e c o r d i n g e r r o r and any b l a s t i n d u c e d damage. The c r i t i c a l p a r a m e t e r s w i l l be s u b s e q u e n t l y i n c o r p o r a t e d i n t o a g o v e r n i n g e q u a t i o n i n C h a p t e r 8 w h i c h . w i l l a n a l y z e f u r t h e r the s i g n i f i c a n c e of s t o p e c o n f i g u r a t i o n . 164 7.2 S t a t i s t i c s In o r d e r to a s s e s s the s u i t a b i l i t y of i n d i v i d u a l sample p o p u l a t i o n s to be d e s c r i b e d by an a p p r o p r i a t e f u n c t i o n , m u l t i v a r i a t e s t a t i s t i c a l methods were e m p l o y e d . T h i s a n a l y s i s has been u sed to d e s c r i b e d a t a t h a t i s t oo numerous to be v i s u a l l y a n a l y z e d . T h i s a l l o w s v a l u e s to be p r e d i c t e d a l o n g w i t h a q u a n t i t a t i v e a p p r a i s a l of the r e l i a b i l i t y o f t h e p r e d i c t i o n . K o c h ( 1 9 8 0 ) s u g g e s t s t h a t s e l e c t i n g a s u i t a b l e mode l depends on " t a s t e , j u d g e m e n t and l u c k " . I t i s a l s o s u g g e s t e d t h a t the p r e d i c t i v e mode l be c h o s e n i n r e l a t i o n to the d a t a base a v a i l a b l e . A s i m p l e mode l s u c h as a l i n e a r or q u a d r a t i c p o l y n o m i a l i s p r e f e r r e d when the d a t a b a s e p a r a m e t e r s a re not w e l l d e f i n e d . A more c o m p l i c a t e d mode l s u c h as a h i g h e r - o r d e r p o l y n o m i a l or f o u r i e r s e r i e s may be u s e f u l i f the d a t a base i s w e l l d e f i n e d and l o c a l v a r i a b i l i t y i s low and w e l l c o n t r o l l e d . A s u f f i c i e n t l y c o m p l i c a t e d f u n c t i o n w i l l f i t any g i v e n s e t of d a t a , h o w e v e r , t h i s f u n c t i o n i s n o t u n i q u e ( K o c h , 1 9 8 0 ) . T h e r e f o r e , one s h o u l d no t emp loy m u l t i v a r i a t e s t a t i s t i c a l a n a l y s i s w i t h the hope of g e n e r a t i n g i n c r e a s i n g l y more c o m p l i c a t e d f u n c t i o n s w i t h the g o a l of I d e n t i f y i n g a " c o r r e c t " p r e d i c t i v e r e l a t i o n s h i p . T h i s c h a p t e r e m p l o y s m u l t i v a r i a t e l i n e a r c o r r e l a t i o n s 165 between the c o n t r o l p a r a m e t e r " d i l u t i o n " and the p a r a m e t e r s i n f l u e n c i n g the c o n t r o l p a r a m e t e r . I n i t i a l l y l i n e a r c o r r e l a t i o n s between two p a r a m e t e r s , i e . D i l u t i o n and A r e a , w i l l be a s s e s s e d and s u b s e q u e n t l y a c u r v e to a p l a n e w i l l be f i t t e d and e x t e n d e d to a l i n e a r h y p e r - s u r f a c e . T h i s form of e x p r e s s i o n e x h i b i t s a l i n e a r v a r i a n c e between the dependent and i n d e p e n d e n t v a r i a b l e s e m p l o y e d . They may be r e p r o d u c e d as f o l l o w s : D i l u t l o n ( % ) = A + B(x) l i n e D i l u t i o n ( % ) = A + B(x) + C ( y ) p l a n e D i l u t i o n ( % ) = A + B(x) + C ( y ) + D(w) + ... l i n e a r h y p e r - s u r f a c e where: D i l u t i o n - I n d e p e n d e n t p a r a m e t e r A,B,C,D - C o n s t a n t s x,y,w - Dependent p a r a m e t e r s The n e x t most c o m p l i c a t e d e x p r e s s i o n w i l l be a t t e m p t e d , C h a p t e r 8, which i s a q u a d r a t i c s u r f a c e . I t i s e x p r e s s e d as f o l l o w s : D i l u t i o n ( % ) = A + B(x) + C ( x 2 ) q u a d r a t i c l i n e D i l u t i o n ( % ) = A + B(x) + C ( x 2 ) + D(y) + E ( y 2 ) + F ( x y ) q u a d r a t i c s u r f a c e T h i s s e c t i o n w i l l e m p l o y e d . The r e a d e t a i l e d t r e a t i s e b r i e f l y o u t l i n e the s t a t i s t i c a l c o n c e p t s der i s r e f e r r e d to Koch(1980) f o r a more o n t h i s t o p i c . 166 7.2.1 D e f i n i t i o n o f S t a t i s t i c a l Terms M u l t i v a r i a t e a n a l y s i s a t t e m p t s t o r e l a t e i n d e p e n d e n t p a r a m e t e r s t o the d e p e n d e n t p a r a m e t e r s , i n te rms of a r e l a t i o n s h i p e x p r e s s e d i n m a t h e m a t i c a l f o r m , by d e t e r m i n i n g an e q u a t i o n c o n n e c t i n g the v a r i a b l e s . A f i r s t s t e p i s the c o l l e c t i o n of d a t a s h o w i n g c o r r e s p o n d i n g v a l u e s of the v a r i a b l e s . F i g u r e 7.1 shows how a c u r v e i s f i t t e d to a " s c a t t e r d i a g r a m " . In o r d e r to a v o i d i n d i v i d u a l j u d g e m e n t i n c o n s t r u c t i n g l i n e s , p a r a b o l a s , o r o t h e r a p p r o x i m a t i n g c u r v e s , i t i s n e c e s s a r y to a g r e e on a d e f i n i t i o n o f a " b e s t - f I t t i n g c u r v e " . In F i g u r e 7.1 the i n d e p e n d e n t p a r a m e t e r i s " x " and the d e p e n d e n t i s " y " ( d i l u 1 1 on ) . The g o o d n e s s of f i t i s d e t e r m i n e d by the d e v i a t i o n o f the " y p r e d i c t e d " f r o m the " y o b s e r v e d " p a r a m e t e r ( y 1 ) . C o n s e q u e n t l y , where the f o l l o w i n g r e l a t i o n Is a minimum, one a r r i v e s a t the b e s t f i t c u r v e d e f i n i n g the r e l a t i o n s h i p b e t w e e n the v a r i a b l e s : 2 2 o d l + d 2 + . . . . + d n = a minimum w h e r e : dn = (y p r e d i c t e d ) - (y o b s e r v e d ) A c u r v e a p p r o x i m a t i n g the d a t a i n F i g u r e 7.1 i s s a i d to f i t the d a t a i n t he l e a s t - s q u a r e s s e n s e and i s c a l l e d a l e a s t - s q u a r e s l i n e , c u r v e or s u r f a c e . The d e p e n d e n t p a r a m e t e r , i n the c o n t e x t of t h i s t h e s i s , i s d e f i n e d as d i l u t i o n and i s 167 a l s o the c o n t r o l p a r a m e t e r . The i n d e p e n d e n t p a r a m e t e r s , among o t h e r s , are a r e a , r o c k q u a l i t y , e x p o s u r e r a t e and s t o p e c o n f i g u r a t i o n . The l e a s t - s q u a r e s l i n e a p p r o x i m a t i n g the s e t of p o i n t s ( x l , y l ) , ( x n , y n ) has the e q u a t i o n " y = A + Bx " where the c o n s t a n t s "A" and "B" a r e d e t e r m i n e d by s i m u l t a n e o u s l y s o l v i n g t h e e q u a t i o n s : L e a s t S quares L i n e y = A + B ( x ) £y = An + BEx E x y = AEx + B E x 2 (n = no. -of o b s e r v a t i o n s ) S i m i l a r l y , the l e a s t s q u a r e s p l a n e , h y p e r - s u r f a c e and q u a d r a t i c s u r f a c e s a r e a l s o d e t e r m i n e d f rom the " n o r m a l " e q u a t i o n s r e p r e s e n t e d below: L e a s t Squares P l a n e z = A + Bx + Cy E z = n-A + BEx + CEy Exz = AEx + BEx + C E x y £ y z = AEy + BExy + C£y2 L e a s t Squares Q u a d r a t i c L i n e z = A + Bx + Cx 2 E y = nA + BEx + C £ x 2 E x y = AEx + B E x 2 + C E x 3 E x 2 y = A E x 2 + B E x 3 + C E x 4 168 L e a s t Squares H y p e r - S u r f a c e z = A + Bx + Cy + Dw + Et Z z = nA + BEx + CEy + DZw + E£.t Z x z = AZx + B Z x 2 + CEyx + DZwx + E E t x £ y z = ASy + Bsxy + C E y 2 + DEwy + e£ty E.WZ = AZw + BExw + CZyw + DZw 2 + eSltw EL tz =• AElt + BSxt + CZyt + DEwt + e £ t 2 L e a s t S q u a r e s Q u a d r a t i c S u r f a c e z = A + Bx + Cy + Dx 2 + E y 2 + Fxy Z z = nA + BEx + CHy + DSTx + E£y + F£xy I x z = AE.x .+ BEx2+ C£xy + DEx3 + EE.y2x + F £ x 2 y STx 2z = A Z x 2 + BE.x3+ CEx2y + DSx 4 + E E y 2 x 2 + F E x 3 y S.yz = AEy + B£xy + C£y2 + D £ x 2 y + E E y 3 + F E x y 2 E z y 2 = AZy2 + B S x y 2 + C£y3 + D£x2 y 2 + E £ y 4 + F£y3 x S.zxy = A£xy + B E x 2 y + CZxy + DEx3y + ESxy3 + F£x2y2 A c o r r e l a t i o n c o e f f i c i e n t measures how w e l l a p r e d i c t e d s u r f a c e w i l l f i t the sample d a t a . I t i s c a l c u l a t e d as f o l l o w s : r^=JT(y e s t - y obs) = E x p l a i n e d V a r i a t i o n ZXy obs - y o b s ) = T o t a l V a r i a t i o n where: y e s t = p r e d i c t e d v a l u e of i n d e p e n d e n t p a r a m e t e r y obs = mean v a l u e of the o b s e r v e d i n d e p e n d e n t p a r a m e t e r y obs = v a l u e of the o b s e r v e d i n d e p e n d e n t p a r a m e t e r The v a l u e r ^ can be i n t e r p r e t e d as the f r a c t i o n of the t o t a l v a r i a t i o n w h i c h i s e x p l a i n e d by the l e a s t - s q u a r e s r e g r e s s i o n l i n e , " r " measures how w e l l the l e a s t - s q u a r e s r e g r e s s i o n l i n e f i t s the sample d a t a . I f the t o t a l v a r i a t i o n i s e n t i r e l y e x p l a i n e d by the r e g r e s s i o n l i n e , i e . r = +1, i t i s s a i d t h a t t h e r e i s p e r f e c t c o r r e l a t i o n . I f the t o t a l v a r i a t i o n i s e n t i r e l y u n e x p l a i n e d , then the e x p l a i n e d v a r i a t i o n 169 i s z e r o and so " r =0" . In p r a c t i c e , the q u a n t i t y " r " l i e s between "0 and 1 " . A c o r r e l a t i o n c o e f f i c i e n t of - 0 . 8 1 i n d i c a t e s t h a t 66% (100 x ( - . 8 1 ) ). of the v a r i a b i l i t y o f the c o n t r o l ( d i l u t i o n ) p a r a m e t e r i s e x p l a i n e d by the f i t t e d r e l a t i o n s h i p . A c o r r e l a t i o n of - . 2 7 i n d i c a t e s t h a t o n l y 7% of the v a r i a b i l i t y i s e x p l a i n e d by the f i t t e d r e l a t i o n s h i p . The d e v i a t i o n s " y e s t - y o b s " f o l l o w a d e f i n i t e and p r e d i c t a b l e p a t t e r n . The above c o n c e p t s c an be g e n e r a l i z e d to more v a r i a b l e s . S i n c e the m u l t i p l e c o r r e l a t i o n c o e f f i c i e n t , as d e f i n e d p r e v i o u s l y , i s n o t e v a l u a t e d i n te rms of the i n d e p e n d e n t p a r a m e t e r s b u t , o n l y by the c o n t r o l and e s t i m a t e d c o n t r o l p a r a m e t e r . A f u r t h e r i m p o r t a n t p a r a m e t e r d e s c r i b i n g the b e s t f i t c u r v e or e s t i m a t e of the d i l u t i o n p a r a m e t e r i s d e t e r m i n i n g the " c o n f i d e n c e l e v e l s " f o r the r e g r e s s i o n c u r v e . A measure of the s c a t t e r of the e s t i m a t e d d i l u t i o n p a r a m e t e r (y e s t ) f o r a g i v e n v a l u e of x l , x 2 , . . . xn i s d e t e r m i n e d as f o l l o w s : U n b i a s e d S t a n d a r d E r r o r of E s t i m a t e of y on x whe re : n = number of s e t s of o b s e r v a t i o n s N = number of d e g r e e s of f r e e d o m . i e . y . x t h e n N = n - 2 y . x . t t h e n N = n - 3 170 T h i s v a l u e i s c a l l e d the s t a n d a r d e r r o r of e s t i m a t e of the p r e d i c t e d d i l u t i o n g i v e n the i n d e p e n d e n t v a r i a b l e s f rom w h i c h i t was c a l c u l a t e d . I t i s i n h e r e n t to the d e f i n i t i o n of the l e a s t s q u a r e s r e g r e s s i o n c u r v e t h a t the d i f f e r e n c e between the o b s e r v e d and p r e d i c t e d (z - z e s t ) d i l u t i o n be a minimum. T h i s w i l l r e s u l t i n the s m a l l e s t s t a n d a r d e r r o r of e s t i m a t e than f o r any o t h e r p o s s i b l e r e g r e s s i o n c u r v e . The s t a n d a r d e r r o r of e s t i m a t e has p r o p e r t i e s a n a l o g o u s to t h o s e of s t a n d a r d d e v i a t i o n . C o n s t r u c t i n g a p a i r of l i n e s p a r a l l e l to the r e g r e s s i o n l i n e of y on x a t r e s p e c t i v e v e r t i c a l d i s t a n c e s S y x , 2Syx and 3Syx f r o m i t , and i f " n " i s l a r g e e n o u g h , t h e n t h e r e wou ld be i n c l u d e d be tween t h e s e p a i r s of l i n e s a b o u t 68%, 95% and 9 9.7% of the sample p o i n t s r e s p e c t i v e l y , F i g u r e 7 . 2 . T h i s a s sumes t h a t the sample p o p u l a t i o n i s l a r g e and does n o t r e q u i r e one to e s t i m a t e the n o r m a l d i s t r i b u t i o n of the p o p u l a t i o n by means of the " t " s t a t i s t i c . F o r s amp le s i z e s e x c e e d i n g t h i r t y ( 3 0 ) , I t i s c a l l e d a l a r g e s a m p l e , and can be a p p r o x i m a t e d by a n o r m a l d i s t r i b u t i o n and the a p p r o x i m a t i o n w i l l i m p r o v e w i t h i n c r e a s i n g " n " . F o r s a m p l e s of s i z e " n " l e s s t h a n t h i r t y ( 3 0 ) , c a l l e d s m a l l s a m p l e s , t h i s a p p r o x i m a t i o n Is no t as d e s i r a b l e and wor sens w i t h d e c r e a s i n g " n " . T h i s r e q u i r e s t h a t " s m a l l s a m p l i n g t h e o r y " be e m p l o y e d . The above d e f i n i t i o n f o r the u n b i a s e d s t a n d a r d e r r o r of e s t i m a t e f o r the p o p u l a t i o n i s s a t i s f a c t o r y f o r sample s i z e s e x c e e d i n g t h i r t y ( S p i e g e 1 , 1972) . T h i s i s the s i t u a t i o n f o r the R u t t a n d a t a b a s e . 171 A f u r t h e r s t a t i s t i c a l t e s t must be i n t r o d u c e d - the " l e v e l of s i g n i f i c a n c e " . T h i s t e s t i s r e q u i r e d i n o r d e r to d e t e r m i n e t h a t the c o r r e l a t i o n v a l u e s t h a t have been c a l c u l a t e d , have no t done so by c h a n c e . T h i s i n v o l v e s h y p o t h e s i s t e s t i n g , whereby one i s a b l e to d e t e r m i n e whether the v a l u e of the c o r r e l a t i o n c o e f f i c i e n t f o u n d f o r a sample has a r i s e n from a n o r m a l u n i v e r s e . A normal u n i v e r s e i s c h a r a c t e r i z e d by h a v i n g a c o r r e l a t i o n c o e f f i c i e n t of z e r o . A s s o c i a t e d w i t h a sample c o r r e l a t i o n c o e f f i c i e n t i s a d i s t r i b u t i o n . I t i s t h e r e f o r e i m p o r t a n t to d e t e r m i n e whether a c h i e v i n g a p o p u l a t i o n c o r r e l a t i o n c o e f f i c i e n t of z e r o i s e n t i r e l y p o s s i b l e * g i v e n the s p r e a d of the sample r e s u l t s . T h i s r e q u i r e s t h a t the sample c o r r e l a t i o n d i s t r i b u t i o n be a p p r o x i m a t e d by a " t " d i s t r i b u t i o n . The p r o b a b i l i t y must t h e n be d e t e r m i n e d t h a t the s t a n d a r d i z e d d i s t r i b u t i o n , w h i c h r e p r e s e n t s the p o p u l a t i o n c o r r e l a t i o n c o e f f i c i e n t , e x c e e d s z e r o a t a g i v e n s i g n i f i c a n c e l e v e l . V a l u e s of c o r r e l a t i o n c o e f f i c i e n t s f o r d i f f e r e n t l e v e l s of s i g n i f i c a n c e and d e g r e e s of f r e e d o m a r e shown i n T a b l e 7.1. T h i s t a b l e shows the p r o b a b i l i t y of e r r o r i n a c c e p t i n g a sample c o r r e l a t i o n as s i g n i f i c a n t when i t s h o u l d have been r e j e c t e d . G e n e r a l l y s t a t i s t i c i a n s a d o p t the t e r m i n o l o g y t h a t r e s u l t s t h a t a r e : ( S p i e g e l , 1972). - s i g n i f i c a n t a t the 0.01 l e v e l a r e " h i g h l y s i g n i f i c a n t " - s i g n i f i c a n t a t the 0.05 l e v e l but not the 0.01 l e v e l a r e " p r o b a b l y s i g n i f i c a n t " - s i g n i f i c a n t a t l e v e l s l a r g e r than 0.05 are "not s i g n i f i c a n t ' 172 7.3 D i s t r i b u t i o n o f Data Base F i g u r e 7.3 shows the d i s t r i b u t i o n of the d a t a f o r m u l a t i n g the R u t t a n d a t a b a s e . F o r t y - t h r e e (43) s t o p e s were a s s e s s e d from a t o t a l of f o r t y - s i x (46) s i n c e the commencement of m i n i n g . I t was i n t e n d e d to i n c o r p o r a t e a l l s t o p e s . a t . R u t t a n and n o t t o b i a s the r e s u l t s by a s e l e c t i o n p r o c e d u r e . The s t o p e s t h a t were not s e l e c t e d were: - 320 - 19B, a s h r i n k a g e - t y p e of s t o p e . i e . e n t i r e s t o p e b l a s t e d t h e n tramming commenced. C o n s e q u e n t l y , trammed d i l u t i o n i s n o t r e l a t e d to v o i d c r e a t e d . - 370 - 14D, a s h r i n k s t o p e - 370 - 11D, a mine d e v e l o p m e n t p r o b l e m c a u s e d p r e m a t u r e s t o p e s h u t down T a b l e s 7.2a,b,c i d e n t i f y the i n d i v i d u a l p a r a m e t e r s . f o r e a c h i s o l a t e d , e c h e l o n and r i b s t o p e c o n f i g u r a t i o n . An o b s e r v a t i o n c o n s i s t s of the f o l l o w i n g : 1) No. of O b s e r v a t i o n 2) Stope Name T h i s i s d e f i n e d by the' draw l e v e l , t h e s t o p e number and a l e n s d e s c r i p t o r ( l e t t e r ) 173 3) Rock Mass R a t i n g [RMR(%)] T h i s i s d e f i n e d f o r the c r i t i c a l w a l l c o n t a c t . I t n o r m a l l y r e f e r s to the h a n g i n g w a l l c l a s s i f i c a t i o n . 4) S tope H e i g h t [ H t . ( m ) ] T h i s i s a m e a s u r e of the a p p a r e n t s t o p e h e i g h t ( H ' ) as d e f i n e d i n F i g u r e 6 . 5 . 5) S tope W i d t h [ W d t h . ( m ) ] T h i s i s a m e a s u r e of the t r u e s t o p e w i d t h (W) as d e f i n e d i n F i g u r e 6 . 5 . 6) S tope Vo lume [ V o l . ( m 3 ) ] T h i s i s a m e a s u r e of the vo lume of r e s e r v e s m i n e d . O b s e r v a t i o n p o i n t s were s e l e c t e d a t i n t e r v a l s of v o l u m e y i e l d i n g 5000m 3 , 10000m 3 and s u b s e q u e n t l y i n 10000m 3 i n t e r v a l s . 7) D i l u t i o n [ D i l . ( % ) ] T h i s p a r a m e t e r was c a l c u l a t e d as d e s c r i b e d i n C h a p t e r 6 . I t was i n t e r p o l a t e d f rom p l o t s of " c u m u l a t i v e d i l u t i o n " v e r s u s " v o l u m e e x t r a c t e d " , F i g u r e 6 . 2 . The i n t e r p o l a t i o n p r o c e d u r e i s a c t u a l l y a summary of m o n t h l y o b s e r v a t i o n s r e c o r d e d t h r o u g h o u t the s t o p e e x c a v a t i o n h i s t o r y . F o r e x a m p l e , the i s o l a t e d s t o p e d a t a base c o n s i s t s of t w e n t y - t w o (22) s t o p e s , y i e l d i n g s i x t y - o n e (61 ) o b s e r v a t i o n s w h i c h a r e b a s e d upon 200 174 r e c o r d i n g s . T h i s v a l u e i s r e c o r d e d as the t o t a l c u m u l a t i v e d i l u t i o n f o r t h e s t o p e v o l u m e e x t r a c t e d . I t has b e e n c o r r e c t e d f o r the d i l u t i o n t h a t Is r e c o r d e d a t the t i m e of " s l o t b l a s t i n g " . T h i s w i l l be d e s c r i b e d s u b s e q u e n t l y , h o w e v e r , the c o n t r o l p a r a m e t e r has been c o r r e c t e d by s u b t r a c t i n g the " b l a s t c o r r e c t i o n f a c t o r " f rom the o b s e r v e d c u m u l a t i v e d i l u t i o n . The v a l u e r e c o r d e d i n T a b l e 7 .2 r e p r e s e n t s the d i l u t i o n f o r a p a r t i c u l a r v o l u m e of mined r e s e r v e s . The t o t a l d i l u t i o n , h o w e v e r , i s a c t u a l l y the r e c o r d e d v a l u e p l u s the w a l l s l o u g h a t t r i b u t e d to s l o t e x c a v a t i o n . 8) Span [m] T h i s r e p r e s e n t s the s t o p e span f o r t h e v o l u m e o f r e s e r v e s r e m o v e d . I t has been d e t e r m i n e d as o u t l i n e d i n C h a p t e r 6 . 3 . 1 . 9) H y d r a u l i c R a d i u s [m] T h i s v a l u e has been e m p l o y e d t h r o u g h o u t the l i t e r a t u r e by a u t h o r s who have c o n d u c t e d work i n the f i e l d of e m p i r i c a l s t o p e d e s i g n , L a u b s c h e r ( 1 9 7 6 ) , Mathews e t a l ( 1 9 8 1 ) . I t was e m p l o y e d to d e t e r m i n e i f i t w o u l d be a c r i t i c a l p a r a m e t e r In r e l a t i n g the e x p o s e d s u r f a c e a r e a to the c o n r o l p a r a m e t e r . I t i s a f l u i d m e c h a n i c s t e r m ( V e n n a r d and S t r e e t , 1975) t h a t has been e x t e n d e d to d e s c r i b i n g the r a t i o be tween the e x p o s e d s u r f a c e a r e a / e x p o s e d s u r f a c e p e r i m e t e r . Mathews has c o i n e d t h i s t e rm as the " s h a p e f a c t o r " and i t i s r e p r o d u c e d i n F i g u r e 7 . 4 . I t i s e m p l o y e d to d i s t i n g u i s h b e t w e e n one way s p a n n i n g s i t u a t i o n s where one 175 d i m e n s i o n i s p a r t i c u l a r l y l a r g e w i t h r e s p e c t to the o t h e r . I t i s shown by t h i s f i g u r e t h a t when the l o n g to s h o r t span e x c e e d s a p p r o x i m a t e l y 4 : 1 , the change i n the h y d r a u l i c r a d i u s i s m i n i m a l . I t i s f o r t h e s e g e o m e t r i e s t h a t Mathews and L a u b s h e r were p a r t i c u l a r l y t r y i n g to d i s t i n g u i s h . The i n i t i a l p r e m i s e was t h a t a one way s p a n n i n g s i t u a t i o n ( i e . t u n n e l h a v i n g an e x p o s e d s u r f a c e a r e a of 100 0m2 or 100m l o n g by 10m h i g h ) i s more s t a b l e t h a n a s t o p e w a l l of w h i c h l o n g and s h o r t d i m e n s i o n s a r e s i m i l a r (32m l o n g by 32m h i g h ) . T h i s was shown e m p i r i c a l l y , by b o t h L a u b s c h e r and M a t h e w s , to be t r u e . N a r r o w e r o p e n i n g s w o u l d t e n d to add a d e g r e e o f c o n f i n e m e n t a n d / o r i n h i b i t the o c c u r r e n c e of e x p o s e d s t r u c t u r e s . The h y d r a u l i c r a d i u s was d e t e r m i n e d f o r the R u t t a n s t u d y i n an a t t e m p t to r e l a t e the r e s u l t s to a w i d e r d a t a base as c o m p i l e d by p r e v i o u s r e s e a r c h e r s . l t i s g e n e r a l l y the c a s e f o r open s t o p i n g o p e r a t i o n s t h a t the h a n g i n g w a l l and f o O t w a l l s u r f a c e s a r e two-way s p a n n i n g . I t i s u n l i k e l y t h a t the s p a n r a t i o s would e x c e e d 4 : 1 . T h i s was the c a s e a t R u t t a n where a v e r a g e span r a t i o s r a n g e d f r o m 1:1 to 3 : 1 . The e x p o s e d s u r f a c e a r e a was a l s o c a l c u l a t e d f rom the span and s t o p e h e i g h t and c o r r e l a t e d to the c o n t r o l p a r a m e t e r . 10) E x p o s u r e R a t e [ m 2 / r a t h ] T h i s v a l u e r e f e r s to the r a t e of e x c a v a t i o n f o r a p a r t i c u l a r s t o p e . I t i s e x p r e s s e d , i n i t i a l l y , as the volume e x c a v a t e d per m o n t h , F i g u r e 6 . 3 . T h e ' e x p o s u r e r a t e i s 176 s u b s e q u e n t l y c a l c u l a t e d as the r a t e a t w h i c h the h a n g i n g w a l l o r f o o t w a l l a r e a i s e x p o s e d . I t i s e x p r e s s e d as the s u r f a c e a r e a e x p o s e d p e r m o n t h . An example i s shown i n F i g u r e 6 . 3 w h e r e b y , f o r the f i r s t t h r e e months of m i n i n g , the s h a d e d a r e a shown i n F i g u r e 6 . 3 has been e x t r a c t e d , c o n s e q u e n t l y : Ra te of E x c a v a t i o n = LI x H x W / ( 3 m t h s ) = V o l u m e / 3 mths E x p o s u r e Ra te = LI x H / ( 3 m t h s ) = E x p o s e d S u r f a c e A r e a / 3 m t h s or a l t e r n a t i v e l y E x p o s u r e Ra te = Ra te of E x c a v a t i o n / W i d t h where w i d t h ( w ) i s m e a s u r e d p e r p e n d i c u l a r to s t r i k e and r e f e r s to the t r u e s t o p e w i d t h . 11) B l a s t C o r r e c t i o n F a c t o r [ B C F , / . D i l u t i o n ] I t was f o u n d t h a t an i n i t i a l d i l u t i o n was p r e s e n t at l o w e r v o l u m e s o f e x c a v a t i o n . T h i s v a l u e was h i g h e r f o r s t o p e s e x h i b i t i n g a l o w e r r o c k mass q u a l i t y . F i g u r e 7 .5 shows the e f f e c t of s t o p e c o n f i g u r a t i o n on the e x t e n t o f the zone of r e l a x a t i o n . A s l o t i s i n i t i a l l y e x c a v a t e d f r o m f o o t w a l l to h a n g i n g w a l l w h i c h has the d i m e n s i o n s shown i n F i g u r e 7 . 5 . The s l o t e x c a v a t e d e x p o s e s a m i n i m a l w a l l c o n t a c t u n d e r the most f a v o u r a b l e c o n f i n i n g c o n d i t i o n s . G e n e r a l l y t h e s l o t i s 3.7m x 3.7m f o r s u b - l e v e l s t o p e s and 6.1m x 6.1m f o r ITH s t o p e s , e x t e n d s f o r the f u l l s t o p e h e i g h t and i s s u b s e q u e n t l y s l a s h e d f o r t h e f u l l s t o p e w i d t h . T h i s i n i t i a l d i l u t i o n was a n a l y z e d 177 s e p a r a t e l y f rom the d i l u t i o n s o b s e r v e d s u b s e q u e n t l y . I t i s g e n e r a l l y assumed by R u t t a n t h a t d i l u t i o n i n the s l o t a r e a i s n e g l i g i b l e and i f p r e s e n t , i s due to b l a s t i n g . T h i s d i l u t i o n i s t h e n assumed to be c o n s t a n t o v e r the r e m a i n d e r of the s t o p e l i f e , s i n c e the b l a s t p r a c t i c e does n o t c h a n g e . S u b s e q u e n t s e c t i o n s w i l l e v a l u a t e the s i g n i f i c a n c e of i n c o r p o r a t i n g t h i s c o r r e c t i o n to the d a t a b a s e . T h i s i n i t i a l v a l u e was s u b t r a c t e d f r om the s u b s e q u e n t d i l u t i o n f i g u r e s r e c o r d e d to r e s u l t i n a c o r r e c t e d d i l u t i o n r e a d i n g . T h i s f a c t o r would a l s o t e n d to c o m p e n s a t e f o r o b s e r v a t i o n e r r o r i n e s t i m a t i n g d i l u t i o n , s i n c e t h i s v a l u e s h o u l d a l s o r e m a i n c o n s t a n t f o r a g i v e n s t o p e . F i g u r e 7.6 shows t h a t the i n c r e m e n t a l d i l u t i o n i s f a i r l y c o n s t a n t u n t i l 30% of the s t o p e has been e x c a v a t e d . The s l o t 3 T g e n e r a l l y e n c o m p a s s e s a vo lume of 2500 - 3000m . The i n c r e m e n t a l d i l u t i o n shows t h a t 7% i s c o n s t a n t f o r the f i r s t 3000m , a f t e r w h i c h , i t i n c r e a s e s and w i l l be s u b s e q u e n t l y shown to be d i r e c t i l y c o r r e l a t e d to the e n l a r g e d s u r f a c e a r e a e x p o s e d due to m i n i n g . B l a s t damage f o r 270 Z -Zone i s a s s e s s e d a t 7%. T h i s v a l u e i s g e n e r a l l y be tween 0 - 3%. I t has been s y s t e m a t i c a l l y r e c o r d e d f o r the s t o p e s i n the c a l i b r a t e d d a t a b a s e as the d i l u t i o n r e s u l t i n g f r om the s l o t a r e a . The s l o t d i l u t i o n was c a l c u l a t e d as shown above e m p l o y i n g i n c r e m e n t a l d i l u t i o n e s t i m a t e s and r e l a t i n g the v a l u e to the s l o t a r e a e x p o s e d . F i g u r e s 7 . 7 , 7 . 8 , 7 . 9 summar ize the p a r a m e t e r d i s t r i b u t i o n t h a t f o rms the R u t t a n Da ta Ease f o r the I s o l a t e d , e c h e l o n and r i b c o n f i g u r a t i o n s r e s p e c t i v e l y . A s t a t i s t i c a l 1 7 8 e v a l u a t i o n f o r the r e l e v a n t p a r a m e t e r s a n a l y z e d f o r e a c h i n d i v i d u a l c o n f i g u r a t i o n and f o r the t o t a l d a t a base i s shown i n T a b l e 7 . 3 . A mean and a s t a n d a r d d e v i a t i o n i s r e c o r d e d f o r e a c h p a r a m e t e r o u t l i n e d i n F i g u r e 7 . 7 , 7 . 8 , 7 . 9 and T a b l e 7 . 3 . The a v e r a g e d i l u t i o n f o r the f o r t y - t h r e e ( 4 3 ) i s o l a t e d s t o p e s i s 10%, w h e r e a s the a v e r a g e d i l u t i o n as d e r i v e d f rom the i n t e r m e d i a t e g e o m e t r i e s (133 o b s e r v a t i o n s ) i s o n l y 6%. In o r d e r to d e s c r i b e t h e d a t a b a s e , one has to l o o k a t the' I n d i v i d u a l o b s e r v a t i o n s f o r the f i n a l and i n t e r m e d i a t e s t o p e g e o m e t r i e s . I t i s i m p o r t a n t to know the l i m i t a t i o n s o f any e m p i r i c a l l y d e r i v e d f o r m u l a t i o n , s i n c e i t i s o n l y as a c c u r a t e as i t s d a t a b a s e . E x t r a p o l a t i n g the o b s e r v a t i o n s b e y o n d the o b s e r v e d q u a n t i t i e s may have a p o o r e r c h a n c e of p r e d i c t i o n . 7.4 I d e n t i f i c a t i o n of C r i t i c a l Parameters The o b s e r v a t i o n s r e c o r d e d i n T a b l e s 7 . 2 a , b , c fo rm the b a s i s f o r t h e s e l e c t i o n of the p a r a m e t e r s w h i c h have the g r e a t e s t e f f e c t on the c o n t r o l v a r i a b l e " d i l u t i o n " . I n i t i a l l y , d i l u t i o n was c o r r e l a t e d by a p p l y i n g a l i n e a r r e g r e s s i o n a n a l y s i s to the p a r a m e t e r s o u t l i n e d i n F i g u r e 7 . 1 0 . The d i l u t i o n s e n s i t i v e p a r a m e t e r s were e v a l u a t e d w i t h r e s p e c t to the i s o l a t e d d a t a b a s e , t h e r e b y e n s u r i n g t h a t s t o p e c o n f i g u r a t i o n w o u l d n o t b i a s the r e s u l t i n g c o r r e l a t i o n s . The m u t u a l c o r r e l a t i o n s were as f o l l o w s : 179 a) Rock Mass R a t i n g The i n d i v i d u a l p a r a m e t e r s w h i c h combine to f o r m the " R o c k Mass R a t i n g " were a n a l y z e d w i t h r e s p e c t to the c o n t r o l p a r a m e t e r f o r t h e i s o l a t e d d a t a b a s e . The d a t a base i s shown i n T a b l e 7 . 4 . A s t a t i s t i c a l l y s i g n i f i c a n t c o r r e l a t i o n c o e f f i c i e n t must e x c e e d 0 . 2 9 5 g i v e n " n - 2 " d e g r e e s of f r e e d o m . ( 6 1 - 2 = 5 9 ) . I n d i v i d u a l l y , e a c h c o e f f i c i e n t i s n o t s t a t i s t i c a l l y s i g n i f i c a n t , F i g u r e 7 . 1 1 . The h i g h e s t c o r r e l a t i o n was o b t a i n e d b e t w e e n the RQD and d i l u t i o n ( r = - . 2 4 ) . The s t a t i s t i c a l t e s t i s t r u e i n the s e n s e t h a t i t w o u l d s e l e c t or r a n k the most c r i t i c a l p a r a m e t e r s a s s u m i n g t h a t t h e o t h e r p a r a m e t e r s w o u l d n o t o v e r l y b i a s the c o r r e l a t i o n . In o r d e r t o i s o l a t e the e f f e c t o f the o t h e r p a r a m e t e r s , s u c h as the e x p o s e d s u r f a c e a r e a , m u l t i v a r i a t e a n a l y s i s must be e m p l o y e d . T h i s w o u l d e n a b l e the r e s u l t a n t m a r g i n a l i n c r e a s e i n the o v e r a l l " b e s t f i t " e x p r e s s i o n to be a s s e s s e d , F i g u r e 7 . 1 0 . G r o u p i n g a l l the p a r a m e t e r s t h a t c o m b i n e to f o r m the " R o c k Mass R a t i n g " r e s u l t s i n a m u l t i p l e c o r r e l a t i o n o f 0 . 3 . R e l a t i n g the RMR v a l u e w i t h d i l u t i o n r e s u l t s i n an i n c r e a s e d s i g n i f i c a n t c o r r e l a t i o n o f + 0 . 3 6 , F i g u r e 7 . 1 0 . C o n s e q u e n t l y , the RMR i s s e l e c t e d as a p a r a m e t e r t h a t w i l l r e f l e c t the i m p o r t a n c e of r o c k q u a l i t y on d i l u t i o n . T h i s i s n o t to i m p l y t h a t the NGI s y s t e m w i l l n o t be an e q u a l o r e v e n b e t t e r c o r r e l a t i v e p a r a m e t e r . The RMR was c h o s e n due to i t s c o m p a t i b i l i t y to the method of d a t a g a t h e r i n g e m p l o y e d a t R u t t a n . I n c o r p o r a t i n g " E x p o s e d S u r f a c e A r e a " w i t h the 180 I n d i v i d u a l RMR p a r a m e t e r s i n d i c a t e s t h a t t h e y w o u l d a l l i m p r o v e the m u t u a l c o r r e l a t i o n t h a t e x i s t s w i t h d i l u t i o n and a r e a a l o n e . A t h i r d c r i t e r i a f o r s e l e c t i o n o f c r i t i c a l p a r a m e t e r s i s d e s c r i b e d . The d i f f e r e n c e b e t w e e n a c o r r e l a t i o n of 0 .71 and 0 . 7 3 i s n o t s t a t i s t i c a l l y d i f f e r e n t a t the 95% s i g n i f i c a n c e l e v e l ( K o c h , 1 9 8 3 ) and s h o u l d be t r e a t e d j o i n t l y . H o w e v e r , i n o r d e r f o r the d i f f e r e n c e to be s t a t i s t i c a l l y s i g n i f i c a n t , the c o r r e l a t i o n s w o u l d have to g e n e r a l l y d i f f e r by 0 . 2 0 f o r the i s o l a t e d d a t a b a s e . The a p p r o a c h t a k e n by the a u t h o r i s to d e f i n e the most s i g n i f i c a n t p a r a m e t e r s " P r i m a r y P a r a m e t e r s " and to g r o u p the r e m a i n i n g i n t o a l i n e a r o r q u a d r a t i c e q u a t i o n t h a t w o u l d y i e l d t h e h i g h e s t c o r r e l a t i o n c o e f f i c i e n t . A s e c o n d c r i t e r i a was the " C r i t e r i a f o r S e n s i t i v i t y " . In o r d e r f o r a p a r a m e t e r to be c l a s s i f i e d as b e i n g d i l u t i o n s e n s i t i v e , i t must pa s s the t e s t o u t l i n e d i n F i g u r e 7 . 1 2 . The g o v e r n i n g e q u a t i o n w i l l i n c o r p o r a t e the most d i l u t i o n s e n s i t i v e and c o r r e l a t i v e parame te r s . b) S tope D i m e n s i o n s The b e s t f i t p a r a m e t e r s were t h a t o f e x p o s e d s u r f a c e a r e a , h y d r a u l i c r a d i u s and s p a n . A m u t u a l c o r r e l a t i o n between a r e a e x p o s e d and h y d r a u l i c r a d i u s y i e l d e d a c o r r e l a t i o n of +0.96 and the f o l l o w i n g e x p r e s s i o n : A r e a ( m 2 ) = -460 + 2 5 0 [ H y d r a u l i c R a d i u s ( m ) ] r= +.96 s = ± 3 0 0 m 2 1 8 1 A m o n g t h e t h r e e p a r a m e t e r s i n v e s t i g a t e d , h y d r a u l i c r a d i u s a n d a r e a r e s u l t e d i n h i g h e r c o r r e l a t i o n s , F i g u r e 7 . 1 0 . T h e p r i m a r y p a r a m e t e r " A r e a " w i l l b e e m p l o y e d r a t h e r t h a n h y d r a u l i c r a d i u s , d u e t o t h e h i g h c o r r e l a t i o n t h a t e x i s t s b e t w e e n t h e t w o . H o w e v e r , a g o v e r n i n g e q u a t i o n i n t e r m s o f h y d r a u l i c r a d i u s w i l l a l s o b e g e n e r a t e d i n o r d e r f o r t h e a u t h o r t o e n a b l e c o m p a r i s o n o f r e s u l t s t o o t h e r r e s e a r c h e r s . F i g u r e 7 . 1 3 s h o w s t h e r e s u l t a n t m u l t i p l e c o r r e l a t i o n s u p o n c o m b i n i n g R M R a n d s t o p e g e o m e t r y w i t h t h a t o f d i l u t i o n . H i s t o r i c a l l y m i n e o p e r a t o r s a s s o c i a t e d d i l u t i o n w i t h t h a t o f i n c r e a s e d s p a n . I t w a s f o u n d t h a t f o r t h e i s o l a t e d d a t a b a s e t h a t : D i l u t i o n ( % ) = 0 . 4 5 + 0 . 2 7 ( s p a n i n m e t e r s ) r = 0 . 6 8 s = " ± 3 . 8 % T h e g o v e r n i n g e q u a t i o n w i l l a l s o b e g e n e r a t e d i n t e r m s o f s p a n , c ) S t r e s s T h e s i g n i f i c a n c e o f d e p t h o n d i l u t i o n w a s a s s e s s e d i n F i g u r e 7 . 1 0 . I t d i d n o t y i e l d a s t a t i s t i c a l l y s i g n i f i c a n t c o r r e l a t i o n o n i t s o w n . U p o n c o m b i n i n g R M R a n d " A r e a " , a s s h o w n i n F i g u r e 7 . 1 3 , i t o n l y m a r g i n a l l y i n c r e a s e d t h e c o m b i n e d c o r r e l a t i o n ( . 7 6 t o . 7 7 ) . I t , h o w e v e r , w a s n o t s e n s i t i v e a s p e r t h e o r i g i n a l d e f i n i t i o n , F i g u r e 7 . 1 2 . T h e u s e o f f i l l a n d n o f i l l w a s c o r r e l a t e d t o t h e 182 " e c h e l o n " d a t a b a s e s i n c e f i l l i n a d j a c e n t s t o p e s w o u l d o n l y a f f e c t the e c h e l o n and r i b c o n f i g u r a t i o n s . Upon c l o s e r e x a m i n a t i o n o f t h e m i n i n g s e q u e n c e and f i l l i n g c y c l e s , i t was c o n c l u d e d t h a t f i l l was o n l y u s e d as a w o r k i n g p l a t f o r m and n o t as a means o f s t a b i l i z i n g a d j a c e n t a r e a s as i n i t i a l l y p l a n n e d . O n l y f i v e s t o p e s had b e n e f i t e d f rom h a v i n g f i l l i n the a d j a c e n t s t o p e s , a l l o f them b e i n g of the e c h e l o n c o n f i g u r a t i o n : 3 2 0 - 1 8 J 370-20KN 370-19K 430-12D 430-13D H/W (19 o b s . ) E m p l o y i n g m u l t i v a r i a t e a n a l y s i s on t h e e c h e l o n d a t a base does n o t r e s u l t i n an i m p r o v e m e n t i n e i t h e r c o r r e l a t i o n or s e n s i t i v i t y , F i g u r e 7 . 1 4 . The r e s u l t s were s i g n i f i c a n t a t the 99% c o n f i d e n c e l e v e l , h o w e v e r , i t i s o f the a u t h o r ' s o p i n i o n t h a t the d a t a ba se i s n o t s u f f i c i e n t l y l a r g e to be a r e l i a b l e e s t i m a t o r . d) M i n i n g M e t h o d The e x c a v a t i o n and e x p o s u r e r a t e were m u t u a l l y c o r r e l a t e d to d i l u t i o n as shown i n F i g u r e 7 . 1 0 . Upon c o m b i n i n g RMR and A r e a , t h i s r e s u l t e d i n m u l t i p l e c o r r e l a t i o n s as shown i n F i g u r e 7 . 1 3 . The e x p o s u r e r a t e was s u b s e q u e n t l y e m p l o y e d as 183 a u g m e n t i n g the p r i m a r y p a r a m e t e r s s i n c e i t y i e l d e d an o v e r a l l h i g h e r c o r r e l a t i o n and s e n s i t i v i t y . A f u r t h e r a n a l y s i s was c o n d u c t e d on s t o p e s e m p l o y i n g 51mm ( c o n v e n t i o n a l ) and 151mm ( I T H ) d r i l l i n g and t h e i r r e s u l t a n t e f f e c t on d i l u t i o n . The 51mm s t o p e s a r e as f o l l o w s , r e f e r T a b l e 7 . 2 a : 370-10B 370-15C 3 7 0 - 1 9 J 3 7 0 - 1 2 / 1 3 F 430-13D F/W 430-14D 4 3 0 - 1 2 F n o . obs= 29 M u l t i v a r i a t e a n a l y s i s showed t h a t t h i s p a r a m e t e r was n o t s t a t i s t i c a l l y s i g n i f i c a n t , F i g u r e 7 . 1 3 . M i n e s e q u e n c e , w h i c h r e f e r s t o the d i r e c t i o n o f m i n i n g , i e . f o o t w a l l to h a n g i n g w a l l l e n s e s or v i c e v e r s a , was c o r r e l a t e d to the e x p r e s s i o n shown i n F i g u r e 7 .14 f o r the e c h e l o n c o n f i g u r a t i o n . The f o l l o w i n g e c h e l o n s t o p e s were m i n e d f rom h a n g i n g w a l l to f o o t w a l l : 3 2 0 - 1 8 J 370-20KN 370-19K 3 7 0 - 2 1 J 370-21KN 4 3 0 - 2 1 J F/W n o . ob s = 2 1 F i g u r e 7 .14 i n d i c a t e s t h a t the c o r r e l a t i o n c o e f f i c i e n t 184 i mproved upon i n c o r p o r a t i n g mine sequence i n t o the e m p i r i c a l e q u a t i o n and was m a r g i n a l l y s e n s i t i v e . T h i s was f u r t h e r a s s e s s e d by i n t r o d u c i n g the "mine s e q u e n c e p a r a m e t e r " as an o p t i o n . A m i n i n g d i r e c t i o n from h a n g i n g w a l l t o f o o t w a l l would d i c t a t e t h a t the p a r a m e t e r "opt.=0" o t h e r w i s e , i t would be s e t to " o p t . = 1" . . The f o l l o w i n g e q u a t i o n was d e r i v e d : D i l ( % ) = 7 . 1 -.12(RMR) + . 0 0 3 ( A r e a ) + 1 . 4 ( 0 p t ) r=±.81 §=±3% Upon c o m b i n i n g the s e c o n d a r y p a r a m e t e r " E x p o s u r e R a t e " w i t h the e x i s t i n g g o v e r n i n g e q u a t i o n , F i g u r e 7.14, i t i s d e t e r m i n e d t h a t the mine s e q u e n c e does not m a r g i n a l l y improve the o v e r a l l c o r r e 1 a t i o n / s e n s i t i v i t y . In a d d i t i o n the p a r t i a l c o r r e l a t i o n c o e f f i c i e n t ( S e c t . 7.4.1) f o r "mine s e q u e n c e " was f o u n d to not be s t a t i s t i c a l l y s i g n i f i c a n t , F i g u r e 7.16. The " B l a s t C o r r e c t i o n F a c t o r " was c o r r e l a t e d to the RMR and was shown t o be s t a t i s t i c a l l y s i g n i f i c a n t a t the 99% c o n f i d e n c e l e v e l . I t showed t h a t as the Rock Mass R a t i n g i n c r e a s e d , the BCF d e c r e a s e d . O t h e r p a r a m e t e r s a f f e c t i n g the BCF were n o t s t u d i e d s i n c e the f a c t o r s t h a t would c o n t r i b u t e to the BCF were n o t r e c o r d e d i n the o r i g i n a l d a t a base, C h a p t e r 7.3. These f a c t o r s would be d i f f i c u l t to q u a n t i f y ( o t h e r than RMR) s i n c e ' t h e y s h o u l d i n c l u d e a d e t a i l e d a s s e s s m e n t of b l a s t i n g / d r i l l i n g p r a c t i c e s , s a m p l i n g e r r o r i n d i l u t i o n e s t i m a t e and a s t u d y of p o s s i b l e s t r e s s i n d u c e d f a i l u r e t h a t 185 may e x i s t w i t h i n the s l o t a r e a . T h e s e , among o t h e r f a c t o r s , s h o u l d be s t u d i e d i n g r e a t e r d e t a i l i n d e t e r m i n i n g the e x t e n t of the B C F . P r e s e n t p r a c t i c e a t R u t t a n i s to r e d u c e t h e BCF to where the g o v e r n i n g e q u a t i o n i s a b l e t o a c c o u n t f o r a l l the d i l u t i o n t h a t i s a t t r i b u t e d to a s t o p e . The g o v e r n i n g e q u a t i o n i s a c o m b i n a t i o n of the p r i m a r y p a r a m e t e r s : A r e a Rock Mass R a t i n g and the s e c o n d a r y p a r a m e t e r : E x p o s u r e R a t e A s e n s i t i v i t y a n a l y s i s was p e r f o r m e d on the b e s t f i t e q u a t i o n i n c o r p o r a t i n g the r e l e v a n t p a r a m e t e r s f o r the " t o t a l s t o p e " d a t a base (131 o b s . ) , F i g u r e 7 . 1 5 . An a l t e r n a t e method o f a n a l y z i n g the above r e l e v a n t p a r a m e t e r s i s d e s c r i b e d i n t h e f o l l o w s s e c t i o n e m p l o y i n g " p a r t i a l c o r r e l a t i o n c o e f f i c i e n t s " . T h i s was e m p l o y e d i n o r d e r to d e t e r m i n e the s e c o n d a r y p a r a m e t e r s c r i t i c a l to the g o v e r n i n g e q u a t i o n . 186 7.4.1 P a r t i a l C o r r e l a t i o n ( r p ) I t i s o f t e n r e q u i r e d t o m e a s u r e t h e c o r r e l a t i o n b e t w e e n t h e d e p e n d e n t v a r i a b l e ( d i l u t i o n ) a n d o n e i n d e p e n d e n t v a r i a b l e when a l l o t h e r v a r i a b l e s i n v o l v e d a r e k e p t c o n s t a n t . T h i s c a n be o b t a i n e d by d e f i n i n g a c o e f f i c i e n t o f p a r t i a l c o r r e l a t i o n ( S p i e g e l , 1973 ) . I t i s d e r i v e d a s f o l l o w s : r l 2 . 3 = r l 2 - r l 3 x r 2 3 ^ ( l - r 2 i 3 ) x ( i - r 2 2 3 ~ ) r ! 2 . 3 4 = r ! 2 - r ! 3 . 4 x r 2 3 . 4 / U - r 2 l 3 . 4 ) x ( l - r 2 2 3 . 4 ) g i v e n : D i l ( % ) = A + B ( A r e a ) - C(RMR; - D ( E x p . R a t e ) P a r a m e t e r [ 1 ] : [ 3 ] [ 4 ] [ 2 ] r l 2 . 3 = c o r r e l a t i o n c o e f f i c i e n t b e t w e e n p a r a m e t e r [ 1 ] and [ 2 ] w h i l e p a r a m e t e r [ 3 ] i s c o n s t a n t . I n o b t a i n i n g t h i s c o e f f i c i e n t o t h e r p a r a m e t e r s a r e n o t c o n s i d e r e d . r l 2 = c o r r e l a t i o n C o e f f i c i e n t b e t w e e n p a r a m e t e r [ 1 ] and [ 2 ] . r l 2 . 3 4 = r e p r e s e n t s c o r r e l a t i o n c o e f f i c i e n t b e t w e e n p a r a m e t e r [ 1 ] a n d [ 2 ] w h i l e p a r a m e t e r s [ 3 ] a n d [ 4 ] a r e c o n s t a n t a n d o t h e r s a r e n o t c o n s i d e r e d . F i g u r e 7.16 shows t h e p a r t i a l c o r r e l a t i o n c o e f f i c i e n t ( r p ) b e t w e e n t h e s e c o n d a r y p a r a m e t e r s a n d t h e c o n t r o l p a r a m e t e r k e e p i n g "RMR a n d A r e a " c o n s t a n t . S i m i l a r r e s u l t s t o t h a t o f F i g u r e s 7 . 1 3 , 7 . 1 4 a r e o b t a i n e d . T h e o n l y s t a t i s t i c a l l y s i g n i f i c a n t s e c o n d a r y p a r a m e t e r b e i n g t h a t o f " E x p o s u r e R a t e " . F i g u r e 7.10 s h o w s t h a t d i l u t i o n i s l a r g e l y i n s e n s i t i v e t o t h e " s t o p e s p a n / w i d t h " r a t i o when a r e a a n d r o c k mass r a t i n g a r e h e l d c o n s t a n t . 7 . 5 Q u a d r a t i c / L i n e a r I n t e r p r e t a t i o n 187 The above a n a l y s i s was based upon a l i n e a r i n t e r p r e t a t i o n of v a r i a n c e between p a r a m e t e r s . A q u a d r a t i c e x p r e s s i o n was a l s o a t t e m p t e d as shown i n F i g u r e 7.17. F i g u r e 7.18 compares the c o r r e l a t i o n s as d e r i v e d between the p r i m a r y p a r a m e t e r s . T a b l e 7.5 compares the p r e d i c t e d d i l u t i o n s f o r the b e s t f i t l i n e a r and q u a d r a t i c e x p r e s s i o n s e m p l o y i n g the p r i m a r y p a r a m e t e r s . The q u a d r a t i c e q u a t i o n y i e l d s a mean sample d i f f e r e n c e between the o b s e r v e d and p r e d i c t e d d i l u t i o n of 2.1%, whereas the l i n e a r e x p r e s s i o n r e s u l t e d i n 2.5%. I t i s t r u e t h a t the q u a d r a t i c c o r r e l a t i o n r e s u l t s i n a s t a t i s t i c a l l y more s i g n i f i c a n t c o e f f i c i e n t t h an the l i n e a r e x p r e s s i o n , however, upon c l o s e r e x a m i n a t i o n of the e x p r e s s i o n , t h i s i s to be e x p e c t e d . The q u a d r a t i c b e s t f i t e x p r e s s i o n , F i g u r e 7.17, a c t u a l l y i n c o r p o r a t e s the l i n e a r e x p r e s s i o n and t h e r e f o r e would p r o d u c e a b e t t e r f i t . G i v e n "n" o b s e r v a t i o n s , a c u r v e h a v i n g "n" number of p a r a m e t e r s would y i e l d a p e r f e c t c o r r e l a t i o n . T h i s of c o u r s e c o u l d be t h e o r e t i c a l l y p o s s i b l e , but p r a c t i c a l l y d i f f i c u l t to employ and u n d e r s t a n d . C o n s e q u e n t l y , the a d d i t i o n a l q u a d r a t i c s u r f a c e t h a t would i n c o r p o r a t e a l l the s i g n i f i c a n t p r i m a r y and s e c o n d a r y p a r a m e t e r s would have to be of the form of e x p r e s s i o n shown i n F i g u r e 7 . 1 7 ( 3 ) . The m a r g i n a l i n c r e a s e i n p r e d i c t i v e a c c u r a c y doe s n o t w a r r a n t the a d d i t i o n a l c o m p l e x i t y i n h e r e n t to the q u a d r a t i c e q u a t i o n . C o n s e q u e n t l y , l i n e a r i n t e r p r e t a t i o n w i l l be employed s i n c e i t has p r o d u c e d s i g n i f i c a n t c o r r e l a t i o n s c o m p r i s e d of s i m p l y d e f i n e d r e l a t i o n s h i p s . 188 7.6 Observations/Conclusions T h i s c h a p t e r summarizes the p a r a m e t e r s t h a t were found to be p a r t i c u l a r l y s i g n i f i c a n t and s e n s i t i v e to the c o n t r o l p a r a m e t e r " D i l u t i o n " . • t h e g o v e r n i n g e q u a t i o n w i l l i n c o r p o r a t e " A r e a , Rock Mass R a t i n g and the E x p o s u r e R a t e " which s t a t i s t i c a l l y a r e s i g n i f i c a n t a t a 99% c o n f i d e n c e l e v e l . The h y p o t h e s i s a t t h i s p o i n t c o n c l u d e s t h a t : DILUTION IS DIRECTLY RELATED TO THE ROCK QUALITY, THE EXPOSED SURFACE AREA AND THE RATE OF MINING GIVEN THE CONDITIONS PREVAILING FOR THE RUTTAN OREBODY. T a b l e 7.1: V a l u e s o f C o r r e l a t i o n C o e f f i c i e n t f o r D i f f e r e n t L e v e l s o f S i g n i f i c a n c e DEGREES OF FREEDOM PROBABILITY .05 .01 1 .988 1.00 2 .900 .980 3 .805 .934 4 .729 .882 5 .669 .883 6 .621 .789 7 .582 .750 8 .549 .715 9 .521 .685 10 .497 .658 11 .476 .634 12 .457 .612 13 .441 .592 14 .426 .574 15 .412 .558 DEGREES PROBABILITY OF FREEDOM .05 .01 16 .4 .542 17 .389 .528 18 .378 .515 19 .369 .503 20 .360 .492 25 .323 .445 30 .296 .409 35 : .275 .381 40 ; .257 .358 45 ' .243 .338 50 .231 .322 60 .211 .295 70 .195 .274 80 .183 .256 90 .173 .242 100 .164 .230 T a b l e 7 . 2 a : I s o l a t e d S t o p e s D a t a B a s e No. Stope Ht.(m) Wdth.(m) Vol.On3) DU.(Z) Span(m) H.R.(m) E.R.tn^/mth: B.C.F.(X) 1 260 11 F 60 45 8 5000 5 15 6 0.19 3 2 260 11 F 60 45 8 10000 10 53 12 0.23 3 3 260 18 J 51 84 10 5000 3 6 3 0.30 5 4 260 18 J 51 84 10. 10000 6 12 5 0.40 5 5 260 18 J 51 84 10 20000 6 24 9 0.40 5" • 6 260 18 J 51 84 10 300CO 9 34 12 0.30 5 7 260 16 H 80 95 13 5000 2 6" . 5 6.55 6 8 260 16 H 80 95 13 10000 6 15 7 0.36 0 9 260 16 H 80 95 13 20000 7 20 0.37 0 10 260 16 H 80 95 13 30000 8 29 11 0.38 . 0 11 260 16 H 80 95 13 40000 9 46 16 0.21 0 12 270 0 2 46 48 8 5000 6 13 5 0.15 7 13 270 Z 46 48 8 10000 11 26 8 6.69 7 • 14 320 14 BE 25 105 10 5000 20 44 16 0.21 3 15 320 13 E 79 80 10 5000 6 16 7 6.13 -1 16 320 15 H 66 75 17 5000 0 4 2 0.10 5 17 320 15 H 66 75 17 10000. 1 9 4 0.14 5 13 320 15 H 66 75 17 20000 2 17 7 0.22 5 19 320 15 H 66 75 17 30000 3 25 9 0.23 5 20 320 15 H 66 75 17 40000 3 32 11 i 0.22 5 " 21 320 18 JN 81 75 13 5000 9 12 . 5 i 0.22 -1 22 320 19 J 84 75 25 5000 0 8 3 1 0.15 0 23 320 19 J 84 75 25 10000 4 16 7 0.18 0 24 320 19 J 84 75 25 20000 6 32 11 0.16 0 25 320 11 B 41 77. 9 5000 22 45 14 0.20 -1 26 340 11 C 43 40 8 5000 5 16 6 0.13 10 ' 27 340 11 C 43 40 8 10000 9 42 10 0.14 10 28 370 21 JN 3 52 10 5000 14 37 11 6.32 -1 29 370 15 H 80 76 23 5000 6 23 9 0.09 -1 30 370 10 fi 51 63 U 5000 2 8 3 0.12 10 31 370 10 B 51 63 11 10000 3 16 6 0.11 .10 32 370 15 C 51 63 9 5000 0 9 4 0.21 29 33 370 15 C 51 63 9 10000 7 19 7 0.19 29 34 370 15 C 51 63 9 20000 11 43 13 0.17 29 35 370 19 J 43 60 23 5000 0 4 2 0.16 2 36 370 19 J 43 60 23 10000 0 8 4 0.19 2 37 370 19 J 43 60 23 20000 5 15 6 0.20 2 38 370 19 J 43 60 23 30000 13 29 10 0.13 2 39 370 16 H 80 76 20 5000 7 27 10 0.12 -1 40 370 12 13F 70 60 10 5000 0 a 4 0.11 0 41 370 12 13F 70 60 10 10000 3 21 8 0.13 0 42 430 13 D F/W 80 60 32 5000 2 3 1 0.08 0 43 430 13 D F/W 80 60 32 10000 4 5 2 0.13 0 44 430 13 D F/W 80 60 32 20000 5 10 4 0.16 0 45 430 13 D F/W 80 60 32 30000 5 16 6 0.16 0 46 430 13 D F/W 80 60 32 40000 5 21 8 0.16 0 47 430 13 D F/W 80 60 32 50000 6 26 9 0.16 . 0 48 430 13 D F/W 80 60 32 60000 6 31 10 0.16 0 49 430 13 D F/W 80 60 32 70000 1 36 11 0.15 6 50 430 13 D F/W 80 60 32 80000 10 42 12 6.13 6 51 430 14 D 80 60 30 5000 1 3 1 0.06 0 52 430 14 D 80 60 30 10000 3 6 5 0.09 6 53 430 14 D 80 60 30 20000 i 11 5 0.11 0 54 430 14 D 80 . 60 30 30000 8 17 7 0.03 0 55 430 14 D 80 60 30 40000 9 22 8 0.03 0 5b 430 14 D 80 60 30 50000 12 40 12 0.03 0 57 430 21 K 70 52 10 5000 1 10 4 0.21 0 58 430 21 K 70 52 10 10000 1 20 7 0.26 0 59 430 21 K 70 52 10 20000 2 40 11 0.25 0 60 430 12 F 32 85 10 5000 1 6 3 0.11 0 61 430 12 F 32 85 10 • 10CO0 25 X 11 0.10 0 B C F = -1 R e f e r s t o B e n c h e d S t o p e Table 7.2b: E c h e l o n Stopes Data Base ECHELON STOPES DAIA BASE No. Stope RMt(Z) Ht.(m) Wdth.Oo) Vol.(m3) Dil.C) Span(m) H.R.(m) E.R.&i^/mth) B.C.F.U) 1 320 12 BE 47 80 7 5000 11 9 4 0.10 . 4 2 320 12 BE 47 80 7 10000 12 27 10 0.14 4 3 320 18 J 56 73 9 5000 4 15 6 0.21 9 4 320 18 J 56 73 9 10000 10 35 12 0.10 9 5 370 20 KN 45 64 15 5000 1 6 3 0.09 2 6 370 20 KN 45 64 15 10000 3 11 0.12 2 7 370 20 KN 45 64 15 20000 9 22 8 0.15 2 8 370 20 KN 45 64 15 30000 12 46 13 0.13 2 9 370 20 KN 45 64 15 40000 13 49 14 0.13 2 10 370 13 D 49 50 25 5000 1 4 2 0.18 3 11 370 13 D 49 50 25 10000 3 8 3 0.24 3 12 . 370 13 D 49 50 25 20000 3 16 6 0.20 3 13 370 13 D 49 50 25 30000 7 24 8 0.11 3 14 370 13 D 49 50 25 40000 10 35 10 0.10 3 15 370 19 K 62 115 13 5000 0 3 2 0.18 0 16 370 19 K 62 115 13 10000 1 7 3 0.22 0 17 370 19 K 62 115 13 20000 3 14 6 0.21 0 18 370 19 K 62 115 13 30000 4 21 9 0.22 . 0 19 370 19 K 62 U5 13 40000 5 28 11 0.25 0 20 370 19 K 62 115 13 50000 8 35 13 0.22 0 21 370 21 J 60 65 15 5000 0 5 2 0.23 2 22 370 21 J 60 65 15 10000 1 10 4 0.23 . 2 23 370 21 J 60 65 15 20000 3 20 8 0.21 2 24 370 21 J 60 65 15 30000 4 30 10 0.19 2 25 370 21 KN 23 44 8 5000 2 16 6 0.28 7 26 370 21 KN 23 44 8 10000 12 30 9 0.28 7 27 370 12 0 26 85 24 5000 2 3 1 0.04 3 28 370 12 D 26 85 24 10000 7 5 2 0.07 3 29 370 12 D 26 85 24 20000 11 10 4 0.08 3 30 370 12 D 26 85 24 30000 15 38 13 0.08 3 31 430 13 F 33 42 10 5000 1 16 6 0.19 8 32 430 13 F 33 42 10 10000 9 35 10 0.28 8 33 430 12 D 26 85 24 5000 2 3 1 0.04 3 34 430 12 D 26 85 24 10000 7 5 2 . 0.07 3 35 430 12 D 26 85 24 20000 11 10 4 0.08 3 36 430 12 D 26 85 24 30000 15 38 13 0.08 3 37 430 21 J F/W 65 53 24 5000 4 4 2 0.05 2 38 430 21 J F/W 65 53 24 10000 5 13 7 0.04 2 39 430 13 D H/W 52 64 18 5000 2 5 2 0.10 0 40 430 13 D H/W 52 64 18 10000 4 9 4 0.14 0 41 430 13 D H/Uj 52 64 18 20000 6 19 7 0.16 0 42 430 13 D K/W 52 64 18 30000 7 28 10 0.17 0 43 430 13 D H/W 52 64 IS 40000 8 37 11 0.13 0 44 • 430 13 D H/W 52 64 18 50000 8 40 12 0.11 0 NUMBER OF SIOPES = 12 BCF = -1 R e f e r s to Benched Stope T a b l e 7.2c: R i b S t o p e s Data Base RIB STOPES CAIA BASE HIMBER OF STOPES - 9 No. Stope Ht.(m) Wdth. (m) Vol. (ni3) wi.«) Span(ra) H.R.(ra) E.R.(m2/mth) B.C.F.(I) 1 320 10 B 34 112 12 . 5000 0 4 2 0.22 0 2 320 10 B 34 112 12 10000 8 7 3 0.22 0 3 320 10 B 34 112 12 20000 13 15 7 0.25 0 4 320 10 B 34 112 12 30000 16 22 9 0.27 0 5 320 10 B 34 112 12 40000 16 30 12 0.29 0 6 320 10 B 34 112 12 50000 16 37 14 0.30 0 7 320 10 B . 34 112 12 60000 16 44 16 0.31 0 8 320 10 B 34 112 12 70000 • 16 46 16 0.28 0 9 320 12 B 23 106 10 5000 27 20 8 0.24 -1 10 340 12 C 30 40 20 5000 8 6 3 0.12 5 11 340 12 C 30 40 20 10000 10 13 5 0.16 5 12 370 20 J 69 75 22 5000 5 3 1 0.04 I 13 370 20 J 69 75 22 10000 7 6 3 0.08 1 14 370 14 C . 47 65 7 5000 8 12 5 0.16 22 15 370 14 C 47 65 7 10000 13 32 11 0.20 22 16 370 13 J 54 75 .10 5000 2 7 3 0.20 7 17 370 18 J 54 75 10 10000 9 14 6 0.30 2 18 370 18 J 54 75 10 20000 14 29 11 0.37 2 19 370 18 J 54 75 10 30000 14 43 14 0.31 2 20 370 11 F 57 - 50 10 5CO0 9 10 4 0.04 15 21 430 15 D 51 64 15 5000 2 6 3 0.19 0 22 430 15 D 51 64 15 10000 6 11 5 0.23 0 23 430 15 D 51 64 15 20000 9 22 8 0.23 0 24 430 15 D 51 64 15 30000 11 33 11 0.24. 0 25 430 15 D 51 64 15 40000 14 47 13 0.15 0 26 430 20 K 74 46 10 5000 1 11 4 0.28 0 27 430 20 K 74 46 10 10000 1 . 22 7 0.18 0 28 430 20 K 74 46 10 20000 2 38 10 0.21 0 BCF = -1 R e f e r s t o Benched S t o p e T a b l e 7.3: D a t a Base - S t a t i s t i c a l Summary PARAMETER TOTAL ISOLATED ECHELON RIB No. OF STOPES . 43 22 12 9 No. OF OBSERVATIONS 133 61 . 44 28 Rock Mass Rating (Z) 55*19 64*19 47*14 48*16 (56120) (591 22) (451 15) (49*17) EXP. RATE ClOOOmVmth; .18t .09 .181 .09. .15*.07 .221.09 (.181 .08) (.171 .07) (.151.08) (.181.09) HYD. RADIUS (m) 714 7 l4 7*4 815 (1113) (111 3) (1112) (1014) SPAN (m) 20114 21114 19114 21*15 (3lil3) (32*13) (3418) (24*-16) SURFACE AREA (md) 1450J; 1120 1420*-1020 136011085 17051 1545 ;2250ill20) (2254 * 970) (23601 924) (20901-1550) SPAN/WIDTH RATIO 1.611.3 1.611.5 .3.4 11.7) (3.2*1.8) STOPE HEIGHT (m) 71121 63±15 72123 78128 (68120) (68116) (63±21) (70 1 25) BCF m 3 + 6 319 313 3*-7 DILUTION (%) 716 6 + 5 6*4 101 7 d o t 6") (10±6) (101-45 (12175 STOPE DEPIH (m) 368 1 54 356165 385 1 36 369147 360 * 48) (346 i-55) (382 140) (369 1 40) STOPE INCLINATION (• ) 6719 (68X9) STOPE WIETIH (ra) 1819 (1518) iae SPAN/SOU SPAN 5.115 (2.111.1) 1 ( ) Refers to Final Stope. Conf Iguraclon Table 7.4: I s o l a t e d Stopes Data Base - T y p i c a l RMR C l a s s i f i c a t i o n SGLATED SIOPES DATA BASE • TYPICAL R » t C L A S S I F I C AT1DN N o . S t o p * Di 1 C D S t r » B . S04C. C a n d i t I 260 u r 5 , 3 . 20 12 2 260 11 r 10 7 8 20 12 3 260 18 i . 3 . 4 3 10 2 0 4 260 13 J 6 4 3 10 20 5 260 13 J 6 4 B 10 20 6 260 18 J 9 4 8 10 20 7 260 16 « 2 7 • 17 25 20 8 2 6 0 16 H 6 7 17 25 20 260 16 H 7 7 17 25 20 !C 260 16 H 8 7 17 25 20 11 260 16 H 9 7 17 25 20 12 270 0 I 6 5 10 15 ' 12 13 270 0 1 11 6 10 15 12 14 320 |4 9E 20 4 10 6 15 320 13 E 6 7 17 25 20 16 220 15 H 0 7 10 21 : 2 17 320 15 H 1 7 10 2 ! 12 19 320 15 H 2 ; 10 •M 12 19 220 15 H 3 7 10 •M 12 20 320 15 H 3 7 10 2 ! 12 i <k 320 SB JN 9 12 17 20 22 320 19 > 0 12 17 25 2C ri 320 19 J 4 ! 2 17 2 5 20 24 320 19 ; 6 12 17 . 25 20 25 320 11 B /•> 7 8 2 0 6 26 3 4 0 11 C 5 1 8 2 0 6 2? 3 4 0 11 C 9 2 a 20 6 2B 370 21 JN 14 2 3 5 3 2 9 370 15 H 6 17 25 20 30 370 10 B 2 4 8 2 0 6 31 370 10 3 3 4 9 2 0 6 32 370 15 C 0 7 8 20 2 0 3 3 370 15 C 7 7 8 20 20 34 3 7 0 15 C 11 7 3 20 20 3 5 370 19 i 0 7 B 10 3 36 370 19 j 7 8 10 8 37 3 7 0 19 J • 5 7 3 10 8 38 370 19 J 13 7 3 10 8 39 370 16 H 7 17 25 20 40 3 7 0 12 13F 0 7 13 20 20 41 370 12 I 3 F 3 7 13 20 20 42 4 3 0 13 0 F/U i 7 18 25 20 43 430 13 D F/W 4 7 18 25 20 i 44 430 13 1) F/U 5 7 18 25 20 i 45 430 13 D F/W 5 7 13 2 5 . 20 i 46 430 13 0 F/U 7 18 2 5 20 47 430 13 0 F/W b 7 13 2 5 2 0 46 430 13 D F/U 6 7 IS 25 20 49 430 13 0 F/U 7 7 18 2 5 20 50 430 13 D F/U ; 0 7 13 2 5 20 51 430 14 D 1 7 17 25 20 52 430 14 D 3 7 17 25 20 53 430 14 3 5 7 i? 25 20 54 430 14 D 5 7 17 25 20 5 ; 430 14 S i 7 17 25 20 430 14 5 " 1 7 25 20 =7 430 21 < 1 4 17 13 6 56 1 : 0 2 1 ' 1 ' 1 4 < i 13 6 59 430 ' . ' ! < Z 1 11 13 I So 420 12 F 1 5 a 20 3 0 0 . 12 F 25 5 9 20 3 194 Table 7.5: Isolated Stopes Data Base - Comparison Quadratic and Planar Surface Empirical Equations ISOLATED SrOPES DATA BASE - COMPARISON QUADRACIC AND PIANAR SURFACE EWIRICAJ. BqU/glCKS DH(Z) - 6 - 8(WR) + 3.5(*REA) r- .76 S=^3.4% 2 Z DH(%) - 1.1 + 10.3(AREA) - 11.2(RMR) - .7(ARFA) •+ 13.2(RHR) - 7.1(AREA)(RMR) r- .82 S=*2.9 No. RHUS) AREA (m2) Res. DUCt) Quad. DUCO Dlff.Ct) Un. Dll(Z) mt. (X) 1 60 675 5 3 2 4 i 2 60 2385 10 10 0 10 0 3 51 504 3 2 1 4 I 4 51 1008. 6 5 1 5 I 5 51 2016 i 9 3 9 3 6 51 2856 9 12 3 12 3 7 80 570 2 3 1 2 0 8 80 1425 6 6 0 5 1 9 80 1900 7 7 0 6 1 10 80 2755 8 8 0 9 1 11 80 4370 9 7 2 15 6 12 . 46 624 6 3 3 5 1 13 46 1248 11 6 5 7 4 14 25 4620 20 24 4 20 0 IS 79 1280 6 5 1 4 2 16 66 300 0 1 1 2 2 17 66 675 1 3 2 3 - 2 18 66 1275 2 5 3 5 3 19 66 1875 3 8 5 •7 4 20 66 2400 3 9 6 9 6 21 81 900 9 4 5 3 6 22 84 600 0 3 3 1 1 ' 23 L 8 4 1200 4 5 1 3 1 " ii 84 " 2400 6 7 1 8 2 25 41 3465 22 16 6 " 15 7 26 43 640 5 3 2 5 0 27 43 1680 9 9 0 8 1 28 3 1924 14 18 4 12 2 29 80 1748 6 7 1 6 0 30 51 504 2 2 0 4 2 31 51 1008 3 5 2 ... ? , .. 2 32 51 567 0 2 2 4 4 33 51 1197 7 6 1 6 1 34 51 2709 11 12 1 11 0 35 43 240 0 0 0 3 3 36 43 480 0 2 2 4 4 37 43 900 5 5 0 6 1 " 38 43 1740 13 9 '4' • "' 9' 4 39 80 2052 7 7 0 7 0 40 70 480 0 2 2 2 2 41 70 1260 3 5 2 . ^ ,. 2 42 80 180 2 1 1 0 2 43 80 300 4 2 2 1 3 44 80 600 5 3 2 2 3 45 80 960 5 4 1 3 2 46 SO 1260 5 5 0 4 1 47 80 1560 6 6 0 5 1 48 80 1860 6 7 1 6 0 49 80 2160 7 7 0 7 0 50 8U 2520 LO a 2 8 2 51 80 180 1 1 0 0 1 52 80 360 3 2 1 1 2 53 80 660 6 3 •J. - 2 4 54 80 . 1020 8 5 . 3 3 5 55 80 1320 9 5 4 4 5 56 80 2400 12 8 4 8 4 57 .70 520 1 2. 1 2 1 58 70 1040 1 5 4 4 3 59 70 2080 2 8 6 •8 6 60 32 510 1 3 2 5 4 61 32 2550 25 15 10 11 13 v (x„. Vn) X F i g u r e 7 . 1 : S c a t t e r D i a g r a m F i g u r e 7 . 2 : E x a m p l e of S t a n d a r d E r r o r of E s t i m a t e 22 STOPES 62 OBS. (200) CLASS A: 2 STOPES, 4 OBS. (20) CLASS B: 9 STOPES, 33 OBS. (89) CLASS C: 8 STOPES, 20 OBS. (60) CLASS D: 2 STOPES, 3 OBS. (21) CLASS E: 1 STOPE, 1 OBS. (10) T O T A L E C H E L O N 43 STOPES 133 OBS. (432) 12 STOPES 44 OBS. (142) CLASS B: 2 STOPES, 8 OBS. (17) CLASS C: 6 STOPES, 24 OBS. (88) CLASS D: 4 STOPES, 12 OBS. (88) R I B 9 STOPES 28 OBS. (90) CLASS B: 2 STOPES, 5 OBS. (18) CLASS C: 4 STOPES, 12 OBS. (38) CLASS D: 3 STOPES, 11 OBS. (34) F i g u r e 7.3: D i s t r i b u t i o n o f S t o p e s - D a t a Base o 10 zo so 40 so &o 7o so 10 /oo Long Sport Cm) F i g u r e 7.4: Shape F a c t o r ( H y d r a u l i c R a d i u s ) F i g u r e 7.5: M i n o r (Dashed) and Major ( S o l i d ) S t r e s s C o n t o u r s S u r r o u n d i n g S t o p e s a t R u t t a n - P l a n View 270 METRIC LEVEL Z ZONE (ISOLATED STOfg) VOLUME EXCAVttTEDWOOOm3) Figure 7 . 6 : Stope D i l u t i o n - Blasting DISTRIBUTION OF H Y D R A U L I C RAD IUS ISOLATED STOPES (61 OBS.) 0 - 5 6 - 1 0 1 1 - 1 5 1 6 - 2 0 HYDRAULIC RADIUS (m) DISTRIBUTION OF E X P O S U R E RATE ISOLATED STOPES (61 OBS.) 0 .01- .1 .11 - .2 .21 - .3 .31 - .4 EXPOSURE RATE flOOOm / m t h . ) DISTRIBUTION O F E X P O S E D S U R F A C E A R E A ISOLATED STOPES (61 OBS.) 100 -i . 1 -90 -60 -\ 0 - 500 501 - 1000 1001 - 15001501 - 20002001 - 25002501 - 3000S001 - 5000 EXPOSED SURFACE AREA (m ) Figure 7.7a: D i s t r i b u t i o n of Parameters Comprising Isolated Data Base DISTRIBUTION OF STOPE INCLINATION ISOLATED STOPES (22 STOPES - FINAL) STOPE HEIGHT (m) DISTRIBUTION OF ROCK MASS RATING ISOLATED STOPES (61 OBS.) 100 -| 90 -80 H 0 - 20 21 -40 41 - 60 61 - 60 81 - 100 ROCK MASS RATING (X) F i g u r e 7.7b: D i s t r i b u t i o n of P a r a m e t e r s C o m p r i s i n g I s o l a t e d D a t a Base DISTRIBUTION OF S T O P E DILUTION ISOLATED STOPES/F1NAL (22 STOPES) 6 - 1 0 1 1 - 1 5 16 - 20 FINAL STOPE DILUTION (X) 100 SO ' so • 70 • 60 - | 50 • «<H 30 • 20 • 10 • 0 -DISTRIBUTION OF S T O P E WIDTH ISOLATED STOPES (61 OBS.) 6 - 1 0 1 1 - 1 5 1 6 - 2 0 STOPE WIDTH (m) Figure 7 . 7 c : D i s t r i b u t i o n of Parameters Comprising Isolated Data Base DISTRIBUTION OF BLAST CORRECTION FACTOR ISOLATED S T O P E S (81 OBS.) 100 - i 9 0 -8 0 -ZERO . 1 - 5 S.1 - 10 >10 BENCHED BLAST CORRECTION FACTOR (!S) DISTRIBUTION OF STOPE SPAN/WIDTH RATIO ISOLATED STOPES (61 OBS.) 100 -i S O -SO -0 - .68 .66 - 1 1.1 - a 2.1 - 3 3.1 - 4 4.1 - 5 STOPE SPAN/W10TM RATIO DISTRIBUTION OF EXCAVATION RATE ISOLATED S T O P E S (61 O B S . ) 100 -1 SO -8 0 -0 - 1 1.1 - 2 2.1 - 3 3.1 - 4 4.1 - 5 5.1 - 8 EXCAVATION RATE (-1000m /mtt i . ) Figure 7.7d: D i s t r i b u t i o n of Parameters Comprising Isolated Data Base DISTRIBUTION OF LONG SPAN/SHORT SPAN ^ I S O L A T E D S T O P E S ( 8 1 O B S . ) S T O P E H E I G H T / S P A N R A T I O DISTRIBUTION OF STOPE SPAN I S O L A T E D S T O P E S ( 6 1 O B S . ) 1 0 0 - i 9 0 -6 0 -7 0 -6 0 -5 0 -1 - 5 6 - 1 0 1 1 - 1 5 1 6 - 2 0 2 1 - 2 5 2 6 - 3 0 3 1 - 3 5 S T O P E S P A N ( m ) Figure 7.7e : D i s t r i b u t i o n of Parameters Comprising Isolated Data Base DISTRIBUTION OF ROCK MASS RATING RIB STOPES (28 OBS.) 100 - i 9 0 -80 -0 - 2 0 2 1 - 4 0 4 1 - 6 0 6 1 - 8 0 81 - 1 0 0 ROCK MASS RATING (X) DISTRIBUTION OF EXPOSED SURFACE AREA RIB STOPES (28 OBS.) 90 -8 0 -EXPOSED SURFACE AREA ( m ) DISTRIBUTION OF STOPE DILUTION RIB STOPES (26 OBS.) 90 -8 0 -STOPE DILUTION (X) Figure 7 . 8 a : D i s t r i b u t i o n of Parameters Comprising Rib Data Base DISTRIBUTION OF HYDRAULIC RADIUS RIB STOPES (28 OBS.) 90 -80 -HYDRAULIC RADIUS (m) DISTRIBUTION OF EXPOSURE RATE RIB STOPES (28 OBS.) 100 - i 90 -80 H .01 - .1 .11 - .2 .21 - .3 .31 - .4 EXPOSURE RATE 01000m /mlh.) Figure 7.8b: Distribution of Parameters Comprising Rib Data Base D I S T R I B U T I O N O F E X P O S E D S U R F A C E A R E A EH - ECHELON STOPES (44 OBS.) 1 0 0 - i :  9 0 -8 0 -0 - S 0 0 501 - 1000 1001 - 15001501 - 2 0 0 0 2 0 0 1 - 2 5 0 0 2 5 0 1 - 30003001 - 4000 EXPOSED SURFACE AREA ( m ) D I S T R I B U T I O N O F R O C K M A S S R A T I N G EN - ECHELON STOPES (44 OBS.) JOO - j 9 0 -8 0 -0 - 2 0 21 - 4 0 41 - 6 0 61 - 8 0 81 - 100 ROCK U A S S RATING (X) Figure 7 . 9 a : D i s t r i b u t i o n of Parameters Comprising Echelon Data Base o DISTRIBUTION OF HYDRAULIC RADIUS E N - E C H E L O N S T O P E S ( 4 4 O B S . ) 1 0 0 - i 9 0 -BO -0 - 5 6 - 1 0 1 1 - 1 5 H Y D R A U L I C R A D I U S ( m ) DISTRIBUTION OF EXPOSURE RATE E N - E C H E L O N S T O P E S ( 4 4 O B S . ) 1 0 0 - r 9 0 -8 0 -.01 - .1 .11 - . 2 . 2 1 - . 3 E X P O S U R E R A T E ( ' 1 0 0 0 m / m l h . ) Figure 7.9b: Distribution of Parameters Comprising Echelon Data Base 2 0 8 r = -.13 ROCK MASS RQD r = -.24 r = -.36 SPACING — r = -.18 CONDITION r = -.18 D I L 0 STOPE AREA r = +.71 r = +.71 r = +.68 T I 0 N DIMENSIONS S T B R S S r = +.}8 r = -.15 r .= +.17 1 SPAN/WIDTH rp = +.01 nPPTH r - -.07 r = .01 EXPOSURE RATE r = +.02 r = -.17 MINING METHOD — ITH VS CONV. r = +.06(ITH) r = +.25 (FW - HW) ' BLASTING RMR & BCF r = -.35 Figure 7.10: C r i t i c a l Parameters r- -.13 D I L U T I O N •= -.10 r- -.18 r= -.24 1 . LIA I STRENGTH + RQD + SPACING + CONDITION J^r= 0.3 + SENSITIVE D I L U T I O N 7 AREA SPACING I r = . 7 3 + J . STRENGTH l _ r = . 7 2 + ~ RQD r * * r = . 7 3 + CONDITION I r=.73 + SENSITIVE SENSITIVE SENSITIVE SENSITIVE Figure 7.11: R o c k Mass Analysis ACCEPTANCE 100Z INCREASE IN THE MEAN VALUE OF A PARAMETER HAS GREATER THAN A IX (ABSOLUTE) AFFECT ON THE CHANGE IH DILUTION. EXAMPLE DILUTION (Z) - 1.8 - .08(RMR) + .0037(AREA) + «.002(DEPTH) MEAN AREA - 1418a 2 HEAR DEPTH - 368a A) TEST: DEPTH BASE - |.002*368| - 0.7Z DILUTION SENSITIVITY - l.002*(368*2)| - 1.5Z DILUTION (BASE - SENSITIVITYl 4. IX "REJECTED" B) TEST: AREA BASE - |.0037*1418l - 5. ZZ DILUTION SENSITIVITY - 1.0037*0418*2) | - 10.5Z DILUTION |BASE - SENSITIVITY| > 1Z "ACCEPTED" Figure 7.12: C r i t e r i a for S e n s i t i v i t y 210 D I L U T I O N : H R " T " i s s i r - 0.76 + SENSITIVE 5*5. RAO. r - 0.76 + SENSITIVE SPAN r - 0.73 + SENSITIVE R M R + A R E A _£° 0.76 DEPTH EXP. RATE WINING RATE ITH VS CONV INSENSITIVE SENSITIVE INSENSITIVE SENSITIVE RNR + AREA + EXP. RATE DEPTH r= 0.79 INSENSITIVE Figure 7.13: Governing Equations - Derivation for Isolated Stopes D I «• 0 T I O N 1 RMR + AREA r-.79 SENSITIVE / \ \ FILL/NO P I L L EXP. RATE " I H E SEQUENCE r-0.79 r - . 8 3 r ° ' 8 1 INSENSITIVE SENSITIVE HARG. SENSITIVE RMR + AREA + EXP. RATE T MINE SEQUENCE r-.83 INSENSITIVE F i g u r e 7.14: G o v e r n i n g E q u a t i o n s - D e r i v a t i o n f o r E c h e l o n S t o p e s 2 1 1 g i -Q Ui O z < or. SENSITIVITY ANALYSIS - ALL STOPES DIL =9.1-.1(RMR)-8.7(EXP.RATE)+.003(AR) - 1 0 - 2 0 -- 3 0 -- 4 0 VARIANCE IN PARAMETER (%) Figure 7.15: S e n s i t i v i t y Analysis - Data Base = A l l Stopes ISOLATED DILUTION RMR + AREA / P A R T I A L CORRELATION >. / 4 \ X DEPTH KXP. RATE MINING RATE ITH VS CONV rp«+.19 r p — .33 r p — .19 r p - . l 9 ECHELON DILUTION 1 | RMR -I V AREA PARTIAL CORRELATION / \ \ FILL/NO F I L L EXP. RATE MINE SEQUENCE rp-0.01 r p — . 4 2 t p - . 2 8 Figure 7.16: P a r t i a l C o r r e l a t i o n 212 LINEAR : Z = a + b(X) + c(Y) + d(W) + QUADRATIC : Z = a + b(X 2) + c(X) Z = a + b(X) + c(Y) + d(X 2) + e(Y 2) + f(X)(Y) Z = A + b(X) + c(Y) + d(W) + e(X 2) + f ( Y 2 ) + g(w2) + h(X)(Y) + i(X)(Z) + j(Y)(W) + k(X)(Y)(W) Figure 7.17: Comparison - Type of Equation (Linear/Quadratic) I DILOTIOH(I) - ,1 f(AREA)] LINEAR QUADRATIC . r-.71 r-.71 •s-t3.7X S-13.7Z fclLUTION(X) - f(RHRjl LINEAR QUADRATIC r—.36 r " " - * 5 DILUTION(Z)- f(RMR.AREA) 7 ^ LINEAR QUADRATIC DIL(Z) - 6 - 8(RMR) + .0035(AREA) . _ , + .0103(AREA) „„„,,.„„.? DIL(Z) - ^(RMR) - .0000007(AREA) r-,76 « - i 3 . « + 1 3'. 2(RMR) a - .007 l(AREA) X (RNR) t-.82 s - i 2.9Z Figure 7.18: Quadratic/Linear Correlation - Isolated Stopes 213 CHAPTER EIGHT STOPE DESIGN 8.1 Introduction T h i s c h a p t e r e m p l o y s the c r i t i c a l p a r a m e t e r s " R o c k Mass R a t i n g , A r e a and E x p o s u r e R a t e " and i n c o r p o r a t e s them i n t o a g o v e r n i n g e q u a t i o n f o r e a c h i n d i v i d u a l s t o p e c o n f i g u r a t i o n . The i n f l u e n c e of s t o p e c o n f i g u r a t i o n on the p r e d i c t e d d i l u t i o n i s e s t i m a t e d and the b l a s t c o r r e c t i o n f a c t o r i s q u a n t i f i e d s t a t i s t i c a l l y . T h i s i s shown to be an i m p o r t a n t p a r a m e t e r i n e s t a b l i s h i n g an e m p i r i c a l s e t of e q u a t i o n s t h a t wou ld be a r e l i a b l e p r e d i c t o r of d i l u t i o n . 8.2 Stope Configuration The g o v e r n i n g e q u a t i o n s f o r the R u t t a n d a t a base a r e shown i n F i g u r e s 8 . 1 , 8 . 7 a , b , c . T h e y have been d e t e r m i n e d f r om a l e a s t s q u a r e s r e g r e s s i o n a n a l y s i s and a r e b a s e d upon the o b s e r v a t i o n s e s t a b l i s h e d i n the p r e c e d i n g c h a p t e r . In o r d e r to d e t e r m i n e the s i g n i f i c a n c e of s t o p e c o n f i g u r a t i o n , the f o l l o w i n g a n a l y s i s . w a s e m p l o y e d : a) I s o l a t e d + E c h e l o n + Rib • A d a t a base i n c o r p o r a t i n g a l l 133 o b s e r v a t i o n s was 214 e m p l o y e d i n g e n e r a t i n g a b e s t f i t h y p e r - s u r f a c e . T h i s e m p i r i c a l e q u a t i o n d o e s n o t d i s t i n g u i s h b e t w e e n t h e d i f f e r e n t s t o p e c o n f i g u r a t i o n s . T h e g o v e r n i n g e q u a t i o n i s a s shown i n F i g u r e 8.2. E m p l o y i n g t h i s e q u a t i o n a n d t h e o b s e r v a t i o n s f o r t h e i s o l a t e d d a t a b a s e r e s u l t s i n a c o r r e l a t i o n c o e f f i c i e n t o f 0 . 7 8 . E q u a l l y f o r t h e e c h e l o n a n d r i b o b s e r v a t i o n s , t h e p r e d i c t i v e e q u a t i o n w o u l d r e s u l t i n c o r r e l a t i o n s o f .71 a n d .72 r e s p e c t i v e l y . I n a l l t h r e e s i t u a t i o n s t h e c o r r e l a t i o n s a n d t h e r e f o r e t h e b e s t f i t i s l o w e r t h a n t h a t o u t l i n e d i n F i g u r e 8 . 1 . I n a d d i t i o n , a f u r t h e r a n a l y s i s was p e r f o r m e d w h e r e b y t h e i s o l a t e d s t o p e s w e r e d e s i g n a t e d a v a l u e " o p t = 0 " a n d t h e r e m a i n i n g o b s e r v a t i o n s a s s e s s e d a v a l u e o f " o p t - 1 " . T h i s r e s u l t e d i n a m u l t i p l e c o r r e l a t i o n a s s h o w n i n F i g u r e 8.2 o f 0 . 7 7 , a n d a p a r t i a l c o r r e l a t i o n o f 0 . 0 1 . I n a d d i t i o n , t h e s e n s i t i v i y y o f t h e o p t i o n p a r a m e t e r i s l e s s t h a n 1%. H o w e v e r , t h e r e m a i n i n g c o n f i g u r a t i o n s r e s u l t i n s i g n i f i c a n t c o r r e l a t i o n s a n d s e n s i t i v i t i e s . T h i s i m p l i e s t h a t t h e e c h e l o n a n d r i b c o n f i g u r a t i o n s c a n n o t be i n c o r p o r a t e d w i t h t h e r e m a i n d e r o f t h e d a t a b a s e s i n c e c o n f i g u r a t i o n i s a c r i t i c a l p a r a m e t e r . b) G r o u p e d S t o p e s A s i m i l a r a n a l y s i s was c o n d u c t e d on t h e g r o u p e d c o n f i g u r a t i o n s . T h e i s o l a t e d a n d e c h e l o n c o m b i n a t i o n , as shown i n F i g u r e 8.3, r e s u l t s i n a m u l t i p l e c o r r e l a t i o n o f 0.7 9 and a p a r t i a l c o r r e l a t i o n o f 0 . 3 . S i m i l a r l y , i s o l a t e d / r i b a n d e c h e l o n / r i b c o m b i n a t i o n s i n d i c a t e d t h a t t h e c o n f i g u r a t i o n i s 215 s i g n i f i c a n t and s e n s i t i v e . The g r o u p e d e m p i r i c a l e q u a t i o n gave l o w e r c o r r e l a t i o n s f o r an i n d i v i d u a l c o n f i g u r a t i o n t h a n i f a s i n g l e e q u a t i o n d e s c r i b i n g t h a t same d a t a base was e m p l o y e d , F i g u r e 8 . 1 . The above i n d i c a t e s t h a t the i n d i v i d u a l s t o p e c o n f i g u r a t i o n s a r e s t a t i s t i c a l l y s i g n i f i c a n t and t h e i r e f f e c t on d i l u t i o n p a r t i c u l a r l y s e n s i t i v e . They c a n n o t , t h e r e f o r e , be g r o u p e d w i t h o u t e m p l o y i n g some p a r a m e t e r ( o p t ) w h i c h wou ld a c c o u n t f o r c o n f i g u r a t i o n . I n d i v i d u a l g o v e r n i n g e q u a t i o n s w i l l be emp loyed In r e l a t i n g d i l u t i o n to the c r i t i c a l p a r a m e t e r s f o r a p a r t i c u l a r s t o p e c o n f i g u r a t i o n . The g o v e r n i n g d e s i g n e q u a t i o n s a r e s u m m a r i z e d i n F i g u r e 8 . 1 . The e q u i v a l e n t h y d r a u l i c r a d i u s and span f o r m u l a t i o n i s shown i n F i g u r e 8 . 4 . I t Is i n t e r e s t i n g to n o t e t h a t a r e l a t i v e c o m p a r i s o n of g e n e r a t e d d i l u t i o n can be made f r o m the p r e v i o u s a n a l y s i s , F i g u r e 8 . 2 . The i s o l a t e d o p t i o n w o u l d y i e l d a p p r o x i m a t e l y 2% more d i l u t i o n t h a t the e c h e l o n and 1.5% l e s s d i l u t i o n t h a n the r i b c o n f i g u r a t i o n . The r i b wou ld y i e l d a p p r o x i m a t e l y more than the e c h e l o n . C o n s e q u e n t l y , the e c h e l o n y i e l d s the l o w e s t d i l u t i o n f o l l o w e d by the i s o l a t e d and r i b g e o m e t r i e s . T h i s o b s e r v a t i o n has been p a r t l y e x p l a i n e d by C h a p t e r 4 . 3 . 2 . 8.3 B l a s t C o r r e c t i o n F a c t o r T h i s has been p r e v i o u s l y d i s c u s s e d and w i l l be a n a l y z e d In a s t a t i s t i c a l c o n t e x t i n t h i s s e c t i o n . F i g u r e 8.5 shows the o p t i o n of i n c o r p o r a t i n g the "BCF" 216 f a c t o r f o r i n d i v i d u a l s t o p e g e o m e t r i e s . T h e i s o l a t e d d a t a b a s e w o u l d r e s u l t i n t h e m u l t i p l e c o r r e l a t i o n f o r t h e g o v e r n i n g e q u a t i o n t o be r e d u c e d t o 0.64 f r o m 0 . 7 9 . T h i s r e p r e s e n t s a p a r t i a l c o r r e l a t i o n o f 0.6. S i m i l a r l y , s i g n i f i c a n t r e s u l t s a r e shown f o r t h e e c h e l o n a n d r i b c o n f i g u r a t i o n s . F i g u r e 8.6 shows t h e r e s u l t a n t c o r r e l a t i o n f o r a d a t a b a s e , w h e r e b y s t o p e s h a v i n g a BCF v a l u e g r e a t e r t h a n z e r o a r e o m i t t e d . . . ' T h i s w o u l d g r e a t l y r e d u c e t h e n u m b e r o f o b s e r v a t i o n s , h o w e v e r , t h e y a r e s t a t i s t i c a l l y s i g n i f i c a n t a t t h e 9 9 % c o n f i d e n c e l e v e l . O b v i o u s l y , t h e y may p a s s t h e t e s t o f s t a t i s t i c s , b u t n o t t h e t e s t o f p r a c t i c a l a c c e p t a n c e t h a t i s i n h e r e n t t o t h e s t u d y t h r o u g h t h e e x p e r i e n c e d o b s e r v a t i o n s made by t h e a u t h o r . 8.4 Predictive Equations(Governing Equations) F i g u r e 8.1 shows t h e g o v e r n i n g e q u a t i o n s t h a t h a v e b e e n d e r i v e d f r o m t h i s s t u d y a n d w i l l be s u b s e q u e n t l y e m p l o y e d i n e s t i m a t i n g o p t i m u m e x p o s e d d e s i g n d i m e n s i o n s . S i n c e a r e a i s e m p l o y e d r a t h e r t h a n s p a n o r h y d r a u l i c r a d i u s , t h i s w o u l d r e d u c e t h e e r r o r s t h a t may o c c u r i n e s t i m a t i n g t h e s t o p e d i m e n s i o n s f r o m a g i v e n e x c a v a t e d v o l u m e , C h a p t e r 6 . 3 . 1 . T a b l e s 8 . 1 , 8 . 2 , 8 . 3 show t h e c r i t i c a l p a r a m e t e r s f o r t h e i n d i v i d u a l s t o p e c o n f i g u r a t i o n s a s i d e n t i f i e d i n t h e p r e c e d i n g c h a p t e r s . T h e g o v e r n i n g e q u a t i o n s a r e e m p l o y e d t o p r e d i c t t h e d i l u t i o n . T h e s e e q u a t i o n s a r e s u b s e q u e n t l y c o m p a r e d t o t h e o b s e r v e d d i l u t i o n . T h e a v e r a g e a b s o l u t e d i f f e r e n c e i n e s t i m a t i o n i s 2.4% 217 f o r the i s o l a t e d , 1.8% f o r the e c h e l o n and 2.7% f o r the r i b c o n f i g u r a t i o n s . T h e s e e r r o r s of e s t i m a t i o n a r e d e t e r m i n e d f o r the sample and f o r the p o p u l a t i o n e s t i m a t e , F i g u r e 8 . 1 . F i g u r e 8 .7 g r a p h i c a l l y d e p i c t s the p r e d i c t e d v e r s u s o b s e r v e d d i l u t i o n f o r the . i n d i v i d u a l s t o p e d a t a b a s e s . The u p p e r and l o w e r b o u n d i n g l i n e s , F i g u r e 8 . 7 , r e p r e s e n t a 68% (one s t a n d a r d d e v i a t i o n ) c o n f i d e n c e t h a t the o b s e r v e d v a l u e w i l l f a l l w i t h i n the r a n g e s d e l i n e a t e d . A f u r t h e r o b s e r v a t i o n i s t h a t one i s 84% c o n f i d e n t t h a t the o b s e r v e d d i l u t i o n w o u l d be l e s s t h a n the mean e s t i m a t e d d i l u t i o n p l u s one s t a n d a r d d e v i a t i o n . The above i s o n l y t r u e i f the s a m p l e p o p u l a t i o n c a n be a p p r o x i m a t e d by a n o r m a l d i s t r i b u t i o n . P r o b a b i l i t y g r a p h p a p e r i s e m p l o y e d w h i c h p l o t s the c u m u l a t i v e r e l a t i v e f r e q u e n c y of the d i f f e r e n c e s be tween the e s t i m a t e d and o b s e r v e d d i l u t i o n s f o r the i s o l a t e d c a s e , F i g u r e 8 . 8 . The s a m p l e i s " n o r m a l l y d i s t r i b u t e d " s i n c e a l i n e a r p l o t i s a c h i e v e d ( S p i e g e 1 , 1973) . T h i s i s g e n e r a l l y the c a s e s i n c e i t i s i n h e r e n t to the d e f i n i t i o n of c o r r e l a t i o n t h a t the p r e d i c t e d d i l u t i o n i s the mean e s t i m a t e of the b e s t f i t e x p r e s s ! o n . Table 8.1: Comparison Predicted/Observed - Isolated ISOLATED STOPES OATA 3A5E WL'WSEW CE S T O P E S - 2 2 E f f i t i C A L EQUATION ; D I L U T l O w q ) = 8 , 6 - 0 . 0 9 C R H S ) - 1 3 . 2 1 E . l i . ; f C . W B C M E * ) r = 0 . 7 9 . J l . l l ~ ~ N c . 3 t o o » w:r:: E . » . ( « 2 / » t h l R * 5 . UUl) Pr.d. D i l l ! ) D i d . (7.; 260 1 ! f • 6 . 1 9 • 675 3 2 2 2 6 0 1! r 0 . 2 3 2 3 9 5 10 9 I 3 260 IB J :l 0 . 3 0 504 3 ; 4 2 6 0 18 J 5 ! 0 . 4 0 1006 6 3 2 • i 260 18 J 5 : 0 . 4 . ) 2016 6 6 - 0 C 260 IS J v. 0 . 3 0 2356 & 11 -•> 7 260 16 K so 0 . 2 5 570 0 8 260 16 H 80 0 . 3 6 1425 6 2 4 9 260 16 K 3 0 ' 0 . 3 7 1900 7 4 2 :o 260 16 H 80 0 . 3 8 2 7 3 5 8 7 1 •• !1 2 6 0 16 H 8 0 . 0 . 2 1 4 3 7 0 9 15 - 6 I 2 270 0 2 4 6 1 0 . 1 5 6 2 4 6 5 i t l 2 7 0 0 I 46 0 . 0 9 1248 11 3 3 14 3 2 0 14 BE 25 0 . 2 1 4 6 2 0 20 21 -1 15 320 13 E 79 0 . 1 3 1290 6 5 1 16 3 2 0 15 H 66 0 . 1 0 3 0 0 0 2 - 2 17 3 2 0 15 H 66 0 . 1 4 6 7 5 1 3 - 2 18 3 2 0 15 H 6 6 0 . 2 2 1275 2 5 -3 19 3 2 0 15 H • 66 0 . 2 3 1875 3 7 - 4 20 320 15 H 66 0 . 2 2 2 4 0 0 3 9 - 6 21 320 18 J N 31 0 . 2 2 900 9 2 i ->•> 3 2 0 13 J 94 0 . 1 5 6 0 0 0 1 -1 2 3 3 2 0 19 J 8 4 0 . 1 8 1200 ' 4 3 24 3 2 0 19 J 94 0 . 1 6 2 4 0 0 6 3 • 2 25 320 11 B 41 0 . 2 0 3 4 6 5 Tt -26 340 11 C 43 0 . 1 3 6 4 0 5 5 - 0 27 340 I ! C 43 0 . 1 4 1680 9 - 0 2 8 3 7 0 21 J * 3 0 . 3 2 1924 14 11 3 29 370 15 H 9 0 0 . 0 9 1749 6 7 -1 30 370 10 8 5 : 0 . 1 2 504 2 4 - 2 31 370 10 B 51 0 . 1 1 1008 3 6 -i 32 3 7 0 15 C 5> 0 . 2 1 5 6 7 0 3 _T 3 3 37C 15 C 51 0 . 1 9 1197 7 c 1 34 3 7 0 15 C 51 0 . 1 7 2709 11 12 -1 3 5 3 7 0 19 i o.; 6 240 •} 4 - 4 36 3 7 0 19 ; 13 3 . 1 3 430 0 4 •t 3 7 370 19 J 43 3 . 2 0 300 6 - I 36 3 7 0 19 J 43 0 . 1 3 1740 13 i t 3 • 3 3 3 7 0 IS 8 30 0 . 1 2 2 0 5 2 7 3 - ; 40 3 7 0 12 ; 3 f 70 0 . 1 1 4 8 0 0 3 - 3 41 370 12 nr 70 0 . 1 3 1260 ' 3 5 -? 42 430 13 J Tl, 9 0 0 . 0 8 1B0 2 ; i 4 3 430 13 0 r / k 80 0 . 1 3 3 0 0 4 1 3 44 4 3 0 13 D F/U 8 0 0 . 1 6 6 0 0 5 i -45 430 13 D F /k ao 0 . 1 6 960 <: 3 4 [ 4 3 0 13 0 f / k 80 0 , 1 6 1260 4 1 47 430 13 II Tl, 90 0 . 1 6 . 1560 6 5 48 430 13 D f / k 80 0 . 1 6 I 8 6 0 6 6 - 0 4 9 4 3 0 13 0 r/a 9 0 0 . 1 5 2 1 6 0 . 7 3 - l 50 4 3 0 13 D r/k 8 0 0 . 1 3 2 5 2 0 10 9 1 51 4 3 0 14 11 ao 0 , 0 6 180 1 1 - 0 52 4 3 0 14 D 90 0 . 0 9 3 6 0 3 2 : 5 3 4 3 0 14 3 80 0 . 1 1 6 6 0 5 2 4 54 4 3 0 14 D 80 0 . 0 3 1020 8 5 3 55 4 3 0 14 D 8 0 0 . 0 3 1320 ; 3 5b 4 3 0 14 5 3 0 0 . 0 3 2 4 0 0 1 1 10 2 57 430 21 K 70 0 . 2 1 520 1 2 -1 59 430 21 K 70 0 I'.'iO 3 - 2 59 4 3 0 21 k 70 0 . 2 5 2 0 8 0 7 - 5 6 0 4 3 0 12 r 32 •0.11 5 1 0 1 6 - 5 430 12 r • ' 3 ? 0.10 :;5o 25 14 1! Table 8.2: Comparison Predicted/Observed - Echelon E C H E L O N S7QPEE D A T A B A S E M U W 9 E R OF STOFES = 12 E.1P2S1CAL EQUATION ; D l t D T l O N d ) = 1 0 , 3 - 0 . 1 3 U M P ) - I 4 . 8 ( £ . P . ) * 0 . O 0 3 ( A R E A ) N o . S N U I I ; E . R . d ^ . t h i Arei(i a> R * s . O i l U ) P r e d . D i H I ! Dilf.Ul 1 3 2 0 12 BE 47 ' 0 . 1 0 720 11 5 1 320 12 BE 47 0 . 1 4 2160 12 9 3 3 320 15 J 56 0 . 2 1 1095 4 3 1 4 320 13 < 56 0 . 1 0 2555 10 9 1 3 7 0 20 K N 4 5 0 . 0 3 3B4 1 4 -3 6 370 20 K N 45 0 . 1 2 704 3 5 - 2 7 372 20 K N 45 0 . 1 5 1408 9 6 3 S 370 20 K N 45 0 . 1 3 2944 12 11 1 9 2 7 0 20 K N 45 0 . 1 3 3136 13 12 1 10 370 13 D 49 0 . 1 S 200 1 2 -1 11 370 .13 ? 4 9 0 . 2 4 400 3 2 1 12 370 ! 3 ! 49 0 . 2 0 900 3 ; - 0 13 3 7 0 n •; 49 0 . 1 1 1700 ; 6 I 14 370 13 D 49 0 , 1 0 1750 1 0 6 2 15 3 ' 0 19 f. . 62 0 . 1 8 3 4 5 0 1 -1 16 370 -19 K 6 2 0 . 2 2 805 1 1 - 0 17 1 5 r. £ 2 0 . 2 1 1610 4 - 1 13 370 19 1 62 0 . 2 2 2415 4 6 - 2 15 . 370 19 i 0 . 2 5 3220 5 8 -3 20 370 19 K 6 2 0 . 2 2 4 0 2 5 8 11 _q ? i 370 21 J 60 0 . 2 3 3 2 5 0 C - 0 22 270 21 J 0.22 650 1 1 - 0 23 370 21 ; 60 0 . 2 1 1300 3 - 0 24 370 21 J 60 0 . 1 9 1950 • 4 6 - 2 li- Vt 2 : K S I1) 0 . 2 : 704 <; - 3 li 370 21 K N n.'li . 1320 12 ; 5 27 370 1 : 0 := 0.04 . 255 2 7 - 5 28 2 7 0 9 0 . 0 7 425 ; 7 - 0 29 Vii ;: [• - 0 . 0 8 850 11 6 3 30 - ? r 5 2 0 0 . 0 8 3 2 3 0 15 15 - 0 31 430 13 f ?3 0 . 1 9 672 1 5 -4 32 430 ! 3 - f 32 0 . 2 8 1470 9 6 1 3 3 . 4 3 0 12 0 i : 0 . 0 4 2 5 5 2 7 -5 34 420 12 5 ifc 0 . 0 7 425 7 7 - 0 35 }i 37 4 3 0 12 0 3c 0 . 0 8 850 11 8 3 4 3 0 12 t 26 O.OB 3 2 3 0 15 15 - 0 4 3 0 21 J F/U b5 • 0 . 0 5 212 4 1 2 33 4 3 0 21 J r/w S5 0 . 0 4 954 5 4 1 35 4 3 0 13 D H/V 5 : 0 . 1 0 320 2 3 -1 40 4 3 0 13 D HIM 52 0 . 1 4 576 4 3 1 41 4 3 0 13 D H/U. 5 : • 0 . 1 6 1216 £ 5 1 42 430 13 5 K / l l 52 0 . 1 7 1792 7 6 1 «J 430 13 11 H / » « i 0 . 1 3 2368 8 9 -1 44 430 13 0 H / N • >^ 0-11 W O a 1? - 2 Table 8.3: Comparison Predicted/Observed - Rib K18 STOPES DATA BASE NUMBER Of STOPES ' 9 EMPIRICAL EQUATION : D i L l ' T i C N : ! ) = 1 5 . 8 - O . I 8 ( P B 8 ) - 7 .7 < E . P , > • P . o f 2 - . ' * ? E i > ' N o . S t o p e mm E . R . ( » e / » t h i A r » a n c l R * s . O i l U ) P r u J . O i l 11) D i f i . H l 1 3 2 0 10 B 34 0 . 2 2 4 4 8 i l 9 2 3 2 0 10 B 34 0 . 2 2 784 B '.0 - 2 • 3 3 2 0 10 8 34 0 . 2 5 I 6 S 0 13 i ' 1 4 3 2 0 10 3 34 0 . 2 7 2464 16 14 2 5 3 2 0 10 B 34 0 . 2 9 3 3 6 0 16 16 •0 £ 3 2 0 10 B 34 0 . 3 0 4144 16 IB - 2 7 3 2 0 10 B 34 0 . 3 1 . 4 9 2 3 16 20 -4 3 2 0 10 B 34 0 . 2 9 5 1 5 2 i t 21 - 5 9 3 2 0 12 B 23 0 . 2 4 2 1 2 0 . 27 15 12 10 3 4 0 12 C 30 0 . 1 2 2 4 0 6 10 • ;• I I 3 4 0 12 C 30 0 . 1 6 5 2 0 10 11 - l 12 370 20 J 6 9 0 . 0 4 225 5 4 l 13 3 7 0 20 J 69 0 . 0 8 4 5 0 7 4 ; 14 3 7 0 14 C 47 0 . 1 6 7 8 0 3 6 - n 15 3 7 0 14 C 47 0 . 2 0 2 0 8 0 13 11 ; 16 370 18 1 54 0 . 2 0 5 2 5 2 6 - 4 |7 3 7 0 19 J 54 0 . 3 0 1050 9 t 18 3 7 0 IB J 54 0 . 3 7 2175 14 9 5 19 3 7 0 IS J 54 0 . 3 1 3 2 2 5 14 12 2 20 3 7 0 11 F 57 0 . 0 4 500 9 7 2 21 4 3 0 15 0 0 . 1 9 3 8 4 2 6 - 4 22 430 15 9 51 0 . 2 3 704 6 7 . -1 23 4 3 0 15 C 5 ! 0 . 2 3 1409 9 9 0 24 4 2 0 15 0 51 . 0 . 2 4 2 1 1 2 11 10 1 25 4 3 0 15 D 0 . 1 5 3 0 0 8 14 13 1 2£ 430 20 K ' 4 0 . 2 8 5 0 6 1 2 -1 27 4 3 0 20 K 74 0 . 1 8 10! 2 1 4 • 3 28 4 3 0 20 X 74 0 . 2 ! . 17 I S 2 5 - 3 ' 220 ISOLATED STOPES (61 OBS) DIL(Z) = 8.6 - 0.09(RMR) -13.2(EXP.RATE) + .0038(AREA) r=0.79 S= ±3Z ECHELON STOPES (44 OBS) DIL(Z) «. 10.3 - 0.13(RMR) - 14.8(EXP.RATE) + 0.0026(AREA) r=±0.83 s= ± 2Z RIB STOPES (28 OBS) DIL(Z) = 15.8 - 0.18(RMR) - 7.7(EXP.RATE) + 0.0026(AREA) r= i0.8 s= * 4Z where: DIL(Z) - DILUTION (Z) RMR - ROCK MASS RATING (Z) EXP.RATE - EXPOSURE RATE ( '100m /mth) AREA - EXPOSED SURFACE AREA (mZ) Figure 8.1: Governing Equations 221 0 P T I 0 N ISOLATED + ECHELON + RIB (133 OBS) DIL(Z) = 9.1 - .l(RMR) - 8.7(EXP.RATE) + -0033(AREA) r=0.77 **= £ 31 " 1 RIB(O) I ISOLATED(O) I ECHELON(O) DTUZ) -• 10 - " 8 - 8 ^ + 0.0033(AREA) - 0.7(OPT) r = 0.77 rp= 0.01 ! DTL(Z) = 11.0 - .09(RMR) - 11.3(ER) + 0.0033(AREA) - 2.4(0PT) r = 0.79 rp=0.30 DIL(%) = 9.3 - -12(R») " 12-3(m) + 0.0033(AREA) - 2.7(OPT) r = 0.8 rp= 0.34 Figure 8.2: Stope Configuration - A l l Stopes ISOLATED + ECHELON OIL - f(RMR » AREA, EXP.RATE) r-0.77 (109 OBS) T ISOL(l) -(0) ECHEL( DIL(Z) - 8.3 - O.l(RMR) - 13.8(EXP.RATE) + .0034(AREA) + 1.97(0PT) r-0.79 S- t 3.0Z rp-0.30 ISOLATED + RIB DIL - f(RMR,AREA.EXP.RATE) r-0.77 (89 OBS) ISOL(l) RIB(O) RIB + ECHELON DIL - f(RMR,AREA,EXP.RATE) r-0.77 (72 OBS) RIB(l) ECHEL(O) DIL(Z). 11.2 - .16(RMR) - 11.8(EXP.RATE) + .0028(AREA) - 4.K0PT) 0.84 TP-S' -2.9Z 0.53 DIL(X)- 11.7 - .11(RMR) - 12.4(EXP.RATE) + .0O34(AREA) - 1.5(OPT) r- 0.8 S- - 3.51 rp- 0.35 Figure 8.3: Stope Configuration - Combined ISOLATED STOPES (61 OBS) DIL(I) - 8.2 - .12(RMR) -DIL(Z) - 7.0 - .08(RMR) -ECHELON STOPES (41 OBS) DIL(X) - 8.8 - .12(RMR) -DIL(Z) - 8.8 - .10(RMR) -RIB STOPES (28 OBS) DIL(Z) - 16.2 - .22(RNR) -DIL(Z) - 17.6 - .25(R«R) -5.3(EXP.RATE) + .9(HYD.RAD) 7.4(EXP.RATE) + .26(SPAN) z-- 0.78 B - ±3.3Z r t - 0.74 S - i 3.6Z 18.2(EXP.RATE) + .8(HYD.RAD) r l - 0.83 s - i 2 . 3 Z 17.KEXP.RATE) + .23(SPAN) r t - 0.83 s 2.4Z 11.4(EXP.RATE) + ,9(HYD.RAD) r J - 0.81 s -i3.SZ 3.7(EXP.RATE) + .22(SPAN) r*= 0.79 s - - 4.1Z where: RMR - ROCK MASS RATING (Z) EXP.RATE = EXPOSURE RATE ( '1000B 2 /nth) HR - HYDRAULIC RADIUS (•) SPAN - SPAN (m) Figure 8 . 4 : Hydraulic Radius and Span Derivation BCF I S O L A T E D "7 — T -HO BCF \ c - .64 6-i 6.5Z .79 s-*3.2Z rrp-0.6 (OPTION: BCF/NO BCF) E C H E L O N NO BCF "7 BCF / v + r . .83 S-t 2.41 t- .7-4 6- -3.7X rp-0.56 (OPTION: BCF/NO BCF) R I BCF / .8 S-t 4Z BO BCF \ .55 fi-± 7.8Z rp=0.69 (OPTION: BCF/NO BCF) F i g u r e 8.5: I n c o r p o r a t i n g B l a s t C o r r e c t i o n F a c t o r I S O L A T E D (13 STOPES, 36 OBS.) DIL(Z) = 11.9 - .12(RMR) - 12.8(EXP.RATE) + 0.0035(AREA) r=0.78 £=13.4* E C H E L O N (2 STOPES, 12 OBS.) r= 0.98 s=t0.69% R I B (4 STOPES, 16 OBS.) r=0.84 s=t4.4% 8.6: Stopes With "BCF > 0" Omitted From Data Base PREDICTED VERSUS OBSERVED DILUTION ISOLATED STOPES (61 OBS.) 0 4 8 12 16 20 24 OBSERVED DILUTION (%) Figure 8.7a: Predicted Vs Recorded D i l u t i o n PREDICTED VERSUS OBSERVED DILUTION 4 3 12 16 20 OBSERVED DILUTION (%) Figure 8.7b: Predicted Vs Recorded D i l u t i o n PREDICTED VERSUS OBSERVED DILUTION Figure 8.7c: Predicted Vs Recorded D i l u t i o n 225 01 30 <U 20 0-1 : : : . . . . . I- i— -I[I II! •P: K i i ' f •ir ; ; ; ; :S It: H; :::: :~: •rn •- ::n • i i i i i i i :::: :•::' : : i ; nil ; ; : ; i i i i i ; ; ; ; L S I : ; ; ; Mi; ill! ; : ; ; ! ; ; ; ; ::::|:::: ::::|:::: T. ::::  ::::):::: ; ; ! ; ! ; : ; ; mm 1 ::!:: i :::(::- -.L... " t -........ 1 1DILUTION DIFFERENCE (%) Figure 8.8: Cumulative Relative Frequency VS D i l u t i o n Difference 226 CHAPTER NINE APPLICATION 9.1 Introduction T h e g o v e r n i n g e q u a t i o n s , F i g u r e 8 . 1 , w e r e e m p l o y e d t o e s t i m a t e d i l u t i o n s f o r e i g h t ( 8 ) s t o p e s t h a t w e r e m i n e d s u b s e q u e n t t o t h e s t u d y . A b r i e f c o m p a r i s o n b e t w e e n t h e m o s t p r o m i s i n g m e t h o d s i s a l s o s u m m a r i z e d . 9.2 Calibrated Data Base T h e s t o p e s t h a t c o m p r i s e t h e c a l i b r a t e d d a t a b a s e a r e s h o w n i n T a b l e 9 . 1 . T h e y c o n s i s t o f : one i s o l a t e d s t o p e (2 o b s e r v a t i o n s ) two e c h e l o n s t o p e s (7 o b s e r v a t i o n s ) f i v e r i b s t o p e s ( 1 9 o b s e r v a t i o n s ) T h e g o v e r n i n g e q u a t i o n s , F i g u r e 8 . 1 , w e r e e m p l o y e d t o a r r i v e a t an e s t i m a t e d d i l u t i o n . T h e s e r e s u l t s a r e s h o w n i n T a b l e 9.2. An a v e r a g e e r r o r o f e s t i m a t e o f 2.4% was o b t a i n e d . T h e a v e r a g e e r r o r o f e s t i m a t e f o r t h e f i n a l c o n f i g u r a t i o n s was 3%. The v a l u e s w e r e t a b u l a t e d by t h e R u t t a n m i n e p e r s o n n e l a n d t h e " B C F " v a l u e s w e r e r e c o r d e d a s d i l u t i o n a t t r i b u t e d t o t h e s l o t r e m o v a l . The r e s u l t s w e r e s u b s e q u e n t l y a d d e d t o t h e o r i g i n a l 227 d a t a base to a r r i v e a t the e m p i r i c a l e q u a t i o n s shown i n F i g u r e 9.1. The c o e f f i c i e n t s f o r the augmented d a t a base a r e s i m i l a r to the o r i g i n a l g o v e r n i n g e q u a t i o n s o t h e r than f o r the r i b c o n f i g u r a t i o n . The d i f f e r e n c e , however, i n the a b s o l u t e d i l u t i o n , as d e r i v e d t h r o u g h the r e s p e c t i v e e q u a t i o n s , does not d i f f e r g r e a t l y . T h i s was d e t e r m i n e d by c o m p a r i n g r i b d a t a base p r e d i c t e d d i l u t i o n s f o r b o t h e q u a t i o n s , T a b l e s 9.3,8.3. The r e s u l t s i n d i c a t e d t h a t f o r the o r i g i n a l r i b d a t a b a s e , the g o v e r n i n g e q u a t i o n r e s u l t s i n an e s t i m a t e of sample e r r o r . o f £2.7% and the augmented e q u a t i o n would y i e l d an e r r o r of +3.1%. The l a r g e r augmented d a t a base s i m i l a r l y showed t h a t the o r i g i n a l g o v e r n i n g e q u a t i o n y i e l d e d an e r r o r of i 2.4% whereas the augmented e q u a t i o n y i e l d e d a mean sample e r r o r e s t i m a t e of -2.6%. The augmented d a t a base w i l l n o t be i n c o r p o r a t e d i n t o the p r e d i c t i v e s o l u t i o n s i n c e t h e s e r e s u l t s have been d e r i v e d by the mine p e r s o n n e l and have n o t been t h o r o u g h l y a n a l y z e d , as was the case w i t h the o r i g i n a l d a t a b a s e . The c a l i b r a t e d s t o p e s a r e i n c l o s e a p p r o x i m a t i o n to the p r e d i c t i v e d i l u t i o n s y i e l d e d by the g o v e r n i n g e q u a t i o n s o u t l i n e d i n F i g u r e 8.1. 9 . 3 Other Methods The i s o l a t e d da methods of Mathews.et B i e n i a w s k i ( 1 9 7 2 ) . I t t a base was a 1 ( 19 8 1 ) , i s i n t e n d e d compared to the e m p i r i c a l L a u b s c h e r ( 1 9 7 6 ) , B a r t o n ( 1 9 7 4 ) to i n t r o d u c e the methods and a n d 228 to r e l a t e them to t h a t o b s e r v e d at R u t t a n . F i g u r e 9.2 shows the r e l a t i o n s h i p t h a t e x i s t s between t h a t of Mathews and the o b s e r v e d d a t a base a t R u t t a n . The r e a d e r i s r e f e r r e d to P a k a l n i s / R o c k Mass(1985) f o r a t h o r o u g h d i s c u s s i o n c o n c e r n i n g t h i s method. I t i n c o r p o r a t e s the f o l l o w i n g f o u r p a r a m e t e r s , F i g u r e 9.2, i n t o a s t a b i l i t y number: - B a r t o n ' s Q r a t i n g . T h i s v a l u e can be d e r i v e d from the "Rock Mass R a t i n g " . - S t r e s s F a c t o r ( A ) . T h i s f a c t o r e m p i r i c a l l y r e l a t e s the s t r e n g t h of the i n t a c t r o c k to the i n d u c e d s t r e s s . T h i s v a l u e i s e q u a t e d to "1.0" where t e n s i l e zones a r e o b s e r v e d ( R u t t a n ) . - S t r u c t u r e D e f e c t P a r a m e t e r . T h i s f a c t o r r e l a t e s e m p i r i c a l l y the o r i e n t a t i o n of s t r u c t u r e w i t h r e s p e c t to the s t o p s . T h i s f a c t o r i s e q u a t e d to "0.5" f o r s t r u c t u r e p a r a l l e l i n g the s t o p e w a l l s ( R u t t a n ) . - Stope I n c l i n a t i o n P a r a m e t e r . T h i s f a c t o r a c c o u n t s f o r the s t o p e i n c l i n a t i o n . T h i s v a l u e i s e q u a t e d to "5.6" f o r s t o p e s i n c l i n e d a t 70 d e g r e e s ( R u t t a n ) . F i g u r e 9.2 shows t h a t the s t a b i l i t y number ( N ) , once p l o t t e d a g a i n s t the shape f a c t o r ( h y d r a u l i c r a d i u s ) , can be c a t e g o r i z e d i n t o s t a b l e , p o t e n t i a l l y u n s t a b l e or p o t e n t i a l l y c a v i n g r e g i o n s . O b s e r v a t i o n s were p l o t t e d i n terms of o b s e r v e d d i l u t i o n , F i g u r e 9.2. The r e s u l t s c o r r e l a t e ( v i s u a l l y ) w e l l , i n t h a t h i g h e r d i l u t i o n s were p l o t t e d w i t h i n zones of i n s t a b i l i t y , whereas l o w e r d i l u t i o n s were a s s o c i a t e d w i t h more s t a b l e a r e a s . F i g u r e 9.3a r e l a t e s RMR to the c r i t i c a l h y d r a u l i c r a d i u s t h a t would c a u s e i n s t a b i l i t y f o r an open s t o p e o p e r a t i o n as 229 d e f i n e d by L a u b s c h e r . F o r r o c k mass r a t i n g s s i m i l a r to t h a t o f R u t t a n , L a u b s c h e r s u g g e s t e d t h a t the h y d r a u l i c r a d i u s s h o u l d no t e x c e e d 24m. A s t o p e h e i g h t of 60m wou ld d i c t a t e a maximum s t o p e span of 240m. T h i s method of d e s i g n i s no t b a s e d upon o b s e r v a t i o n s f r om open s t o p i n g , but f rom c a v i n g o p e r a t i o n s . The e x p o s e d s u r f a c e a r e a i n c a v i n g o p e r a t i o n s i s g e n t l y s l o p i n g , whereas i n open s t o p e o p e r a t i o n s , the h a n g i n g w a l l i s g e n e r a l l y i n c l i n e d . The a u t h o r wou ld l i k e to n o t e t h a t the d e f i n i t i o n as o r i g i n a l l y s t a t e d by L a u b s c h e r i n d e s c r i b i n g h y d r a u l i c r a d i u s f o r an open s t o p e , i s vague s i n c e i t was d e r i v e d f o r c a v i n g o p e r a t i o n s where f l a t b a c k s a r e the norm. The h y d r a u l i c r a d i u s , as d e f i n e d i n C h a p t e r 7 was e m p l o y e d i n the a u t h o r ' s i n t e r p r e t a t i o n of c r i t i c a l ' s p a n . F i g u r e 9.3b shows t h a t B a r t o n wou ld d e s i g n u n s u p p o r t e d spans be tween 10 to 20m f o r the a v e r a g e r o c k mass r a t i n g s r e c o r d e d a t R u t t a n . B i e n i a w s k i wou ld p r e d i c t u n s u p p o r t e d spans of be tween 4 to 9m, F i g u r e 9 . 3 c . T h i s shows the c o n s e r v a t i s m a s s o c i a t e d w i t h the i n d i v i d u a l d a t a b a s e s w h i c h were d e r i v e d p r i m a r i l y f rom c i v i l p r o j e c t s . F i g u r e 9.4 shows the method as p r o p o s e d by Beer and Meek(19 8 2) i n terms of p r e d i c t i n g s t o p e spans e m p l o y i n g V o u s s o i r a r c h t h e o r y . I t i s p a r t i c u l a r l y a p p l i c a b l e i n the d e s i g n of e x c a v a t i o n s i n w e l l - b e d d e d f o r m a t i o n s where the d i r e c t i o n of t h e . b e d d i n g ' p l a n e s p a r a l l e l the l o n g d i m e n s i o n of the o p e n i n g . I t i s assumed t h a t the g r o u n d above the h a n g i n g w a l l i s c o m p l e t e l y d e s t r e s s e d i n the d i r e c t i o n n o r m a l , to 230 b e d d i n g . In a d d i t i o n , i t a s sumes t h a t the r o c k mass has p a r t e d a l o n g smooth b e d d i n g p l a n e b r e a k s , t h e r e b y f o r m i n g a s e r i e s o f " n o - t e n s i o n " beam members . F a i l u r e c o u l d be by " f l e x u r a l " or " s h e a r " f a i l u r e , as i n d i c a t e d i n F i g u r e 9 . 4 a . F i g u r e 9 .4c shows the s u g g e s t e d c r i t i c a l ' s p a n g i v e n t h e : - s t r a t a t h i c k n e s s (0.3m - lm) - modu lus of d e f o r m a t i o n f o r the r o c k mass (8000MPa) - s t o p e i n c l i n a t i o n ( 6 5 ° ) - u n i a x i a l c o m p r e s s i v e s t r e n g t h (100 MPa) C u r v e " A " i n F i g u r e 9 . 4 c d e s c r i b e s the p l a n e s t r a i n s i t u a t i o n , whereas c u r v e " E " d e s c r i b e s t h a t of a s q u a r e h a n g i n g w a l l . The i n t e r m e d i a t e c u r v e s r e l a t e the c r i t i c a l d e s i g n f o r the r e c t a n g u l a r c o n f i g u r a t i o n s , F i g u r e 9 . 4 b . The f o l l o w i n g p a r a m e t e r s a r e r e q u i r e d f o r i n p u t i n t o F i g u r e 9 . 4 c : - the a v e r a g e j o i n t s p a c i n g a t R u t t a n f o r the i s o l a t e d d a t a b a s e i s 0.3m to lm , T a b l e 7.4 - the i n - s i t u modu lu s of d e f o r m a t i o n f o r an "RMR=64%" i s 22GPa , A p p e n d i x I I . A c c o r d i n g to B r o w n ( 1 9 8 5 ) , the v a l u e s h o u l d be h a l v e d , t h e r e b y e m p l o y i n g a f a c t o r of s a f e t y of two. C o n s e q u e n t l y , the i n - s i t u modu lu s i s l l G P a f o r the R u t t a n d a t a b a s e . - The u n c o n f i n e d c o m p r e s s i v e s t r e n g t h i s 50 -100MPa, T a b l e 7 . 4 . E m p l o y i n g a p p r o x i m a t e the the c u r v e s shown i n F i g u r e 9 c r i t i c a l . s u g g e s t e d span g i v e . 4c wou ld n the above Input 231 p a r a m e t e r s . T h i s a n a l y s i s s u g g e s t s t h a t the c r i t i c a l span s h o u l d no t e x c e e d 20m to 45m. The s i m i l a r i t y i n the p r e d i c t e d and a c t u a l o b s e r v e d spans e m p l o y e d a t R u t t a n i n d i c a t e t h a t the V o u s s o i r method does have a p p l i c a t i o n s f o r s t o p e d e s i g n . The d i f f i c u l t y a r i s e s i n e s t i m a t i n g the s t r a t a t h i c k n e s s and i n c a l i b r a t i n g the s t r e n g t h p a r a m e t e r s to t h a t of the mine d a t a base . The a l t e r n a t i v e methods were i n t r o d u c e d to show t h a t w o r k a b l e s o l u t i o n s can be o b t a i n e d w i t h the i n c r e a s e d a p p l i c a t i o n of t he i n d i v i d u a l methods and the s u b s e q u e n t c a l i b r a t i o n to a c t u a l o b s e r v a t i o n s . T h i s wou ld r e s u l t i n a more c o m p r e h e n s i v e method f o r the d e s i g n of open s t o p e s p a n s . Table 9.1: Stopes Mined Subsequent to Study CALIBRATED DATA BASS. - STOPES MINED SUBSEQUENT TO STUDY (8 Stopes) No. Stope RMlCZ) Ht.(m) Wdth. (ra) Vol.On3) Ml. 0 0 Span(m) H.R.(m) E.R.(m2/mth) B.C.F.«) ISOLATED STOPES 1 I 320 0 I 1 80 I 125 7 5000 I 4 6 I 3 J 0.21 1 0 2 1 320 0 I 1 80 1 125 7 10000 | 5 13 | 6 1 0.24 | 0 Etna 3 •ON STOPES 490 1 D 49 . 45 23 5000 5 2 0.12 3 4 490 1 D 49 45 23 10000 3 10 4 0.13 3 5 490 1 0 49 45 23 20000 3 20 7 0.14 3 6 490 1 D 49 45 23 30000 5 30 9 0.16 ~3" 7 490 1 D 49 45 23 40000 7 40 11 0.16 3 8 370 14 a. 47 50 7 5000 5 15 6 0.15 3 9 370 14 CW 47 50 7 5400 5 25 8 0.15 3 RIB 5 10 -[OPES 260 17 J 53 25 13 5000 1 15 5 0.21 4 11 260 17 J 53 40 *3 10000 2 19 6 0.25 1  1 " 12 260 17 J 53 60 13 20000 3 26 9 ' 0.31 ~i 13 260 17 J 53 60 13 30000 8 40 12 0.33 4 14 260 17 J 53 60 13 36000 12 50 14 0.33 -J " 15 260 4 /5CR0P d7 " 75 13 5000 3 5 2 0.26 3 16 260 4 / 5CHDP 67 75 13 10000 3 10 4 0.36 "3 17 260 4 /5CROP 67 75 13 20000 4 21 8 . 0.33 3 18 260 4 / 5CROP 67 75 13 30000 5 " " •'56' " "TT"" 0.35 - j - -19 260 4 /5CR0P 67 75 13 40000 5 41 13 0.37 3 20 260 4 /5CROP 67 75 13 44000 6 50 15 0.36 3 21 260 15 H 78 78 12 13&0 3 31 9 0.57 "o" 22 340 9 C 26 28 6 5000 9 "30 " "7 ' 0.35 T " 23 340 9 C 26 28 6 7100 14 50 9 0.35 T 24 4X 20 J 71 43 17 5000 1 ' 6 3 0.11 0 25 430 20 J . 71 48 17 10000 3 12 5 0.13 0 26 430 20 J 71 48 17 20000 4 25 8 0.19 0 27 430 20 J 71 48 17 30000 6 37 10 0.20 0 28 430 20 J 71 48 17 328000 8 40 11 0.21 0 b l e 9.2: C a l i b r a t e d Data Base - P r e d i c t e d CALIBRATED DATA SASH - STOPES HtMED SUBSEQUENT TO STUDY (B Stones) No. Stope E.R.(Aith) Rts. Di1(Zl. Pr*d.Oi1(I) Diff.m ISOLATED STOPE: S:ii«)= 8.6 - .09IRHR) - 13.2IE.R.) • .03BCAREA1 1 3 1 1) 1 • 1 W 1 0.210 1 750 1 4 2 320 0 ! 1 » 1 0.240 1 1525 1 5 1 4 1 1 ECHELON STOPES: 0IUI! = I0.3 - .13(RHR) - 14.8IE.R.) • .003IAREA) 3 430 1 0 45 0.120 225 3 3 0 4 450 1 C 1- 0.130 450 3 3 -0 490 1 D 49 0.140 900 3 5 -2 6 430 ID. 49 0.160 . 1350 5 6 -1 7 490 1 0 49 0.160 1800 7 7 0 6 370 i4 Ck 47 0.150 750 5 4 1 270 14 Cil 47 0.150 1250 5 6 -1 R.'B E'OPES: D!L-:;i = :5.B - .I8IRNR) - 7.7IE.R.) + .0026(AREA) 10 260 !7 J 52 0.210 375 1 6 L5 260 17 J 53 0.250 760 2 6 -4 1 T 260 17 J 0.310 1560 3 B -5 :3 260 !7 J 0.330 2400 8 10 .2 !4 260 17 ; 53 0.330 3000 12 12 0 15 • 260 4 /5CR0P £7 0.260 375 3 3 0 u 260 4 /5CS0? £7 0.300 750 3 3 . -0 • 7 260 4 /5CR0P 67 0.330 1575 4 5 -1 <i 260 4 /5CR0P £7" 0.350 2250 5 7 -9 260 4 /5CP0F £7 0.370 3075 5 9 -4 260 4 /5CR0? 67 0.360 3750 6 1 -5 260 15 H 79 0.570 . 2496 3 4 -1 >? 340 9 2 ;>; 0.350 840 9 1 -? ;3 340 9 C 26 0.250 1400 14 12 2 24 420 20 J 7'. 0.110 288 t 3 -2 420 20 ; 7! 0.130 576 3 4 -1 26 430 20 .' •>: 0.190 1200 4 5 -1 430 20 J ;; 0.200 1776 6 6 -O '3 . 130 20 J "V- 0.210 1920 8 6 D i l u t i o n T a b l e 9.3: Augmented R i b Data Base 1M STOPES DATA BASE NUBER Of STOPES - 9 ENPIPICAL EQUATION: DILC) = 11.2 - .14(R«R) - 2.3IER) * .0027(AR£Ai r = ,76t=t<l No. Stooe E.t. («2/»th! AREA!.2) Rts. Oi1(Zl Pr.d.Dil(I) r>it(.m 1 320 10 B 34 0.220 448 0 7 -7 0 320 10 B . 34 0.220 • 784 S S -0 i 320 10 B 34 0.250 1680 13 10 3 4 320 10 9 34 0.270 2464 16 12 4 5 320 10 B 34 0.290 3360 16 15 i 6 320 10 B 34 0.300 4144 16 17 -1 7 320 10 B 34 0.310 4928 16 19 -3 320 10 B 34 0.280 5152 16 20 -4 220 12 B 23 0.240 2120 27 12 14 10 340 12 C 30 0.120 240 8 / 1  340 12 C 30 0.160 520 10 6 2 12 370 20 J 69 0.040 7?c 5 2 ; 370 20 J 69 0.080 450 7 3 4 !4 370 14 C 47 0.160 780 8 £ 2 15 270 14 C 47 0.200 . 2090 13 10 3 16 370 IE 1 54 0.200 525 2 5 -3 17 370 IS J 54 0.300 1050 9 6 i 18 370 :=. : 54 0.370 2175 14 9 5 19 370 19 J 54 0.310 3225 14 12 •> 20 370 11 f 57 0.040 . 500 9 4 5 i\ 430 15 D 51 0.190 3B4 2 5 •3 *i 430 15 D . 51 0.230 704 6 5 t 23 430 15 ii 51 0.230 • 1406 S 7 2 24 430 15 E 51 0.240 2112 1 9 i 25 430 15 D • 51 0.150 3008 !4 12 2 26 430 20 /, 74 0.260 506 1 2 -1 27 430 20 r. 74 0.180 1012 i 3 28 430 20 >: 74 0.210 I74B 2 5 -3 ISOLATED STOPES (63 OBS, 23 STOPES) DIL(Z) = 8.4 - .08(RMR) - 12.6(EXP.RATE) + .0038(AREA) r=±0.79 s= ±3.21 ECHELON STOPES (51 OBS. 14 STOPES) DIL(Z) = 10.3 - .13(RMR) - 14.8(EXP.RATE) + .0030(AREA; r= i0.83 s= - 2.3Z RIB STOPES (47 OBS, 14 STOPES) DIL(Z) = 11.2 - .14(RMR) - 2.3(EXP.RATE) + .0027(AREA) r=-0.76 s=±4Z Figure 9.1: Augmented Data Base 235 1,000 100 fl) JO (0 • Refer to Ruttan Observations- Dll(Z) (Isolated) S h a p e Fac tor , S = A r e a / P e r i m e t e r (m) STABILITY NUMBER "ti" The stability number N is determined from the following equation: N =. Q ' x A x B x C . where Q' A B C m o d i f i e d NG I r o c k m a s s r a t i n g r o c k s t r e s s f a c t o r r o c k d e f e c t o r i e n t a t i o n f a c t o r o r i e n t a t i o n o f d e s i g n s u r f a c e f a c t o r Figure 9.2a: Mathews Method of Span Determination (Mathews et a l , 1981) / Z-z..... • 1 p o i r n t i o l i n n a b i h r y «—P-<2) B = ROCK DEFECT FACTOR C = ORIENTATION FACTOR = 8 - 7 X COSIN (STOPE INCLINATION) A = ROCK STRESS FACTOR Of H N T a r lOW  Of HOOF ,.////////////, Figure 9.2b: Design Factors - Mathews Method Hours _ Months ' „ M inutes i 10 Days , , S I ( S I B Yea rs 10 30 1 2 3 5 10 20 . T i i l i i n 2 1 * 1 1 0 20 J M — 1 1 i iwn-— -15m VERY GOOD ;10m ROCK " 8m - 6m - 5m 1 - Urn - 3m 2m tm 0.5m 1 hour 10 10z 103 STAND-UP TIHE - HOURS Figure 9.3c: RMR Method o f Span Determination 238 a / , \ 1 Two Basic Modes of Roof Failure: a) Snap through and b) Shear Failure Diagram Showing Yield Lines for Rectangular Panel 100 ISO SPAN m Design Curves for Rectangular Hanging Wall Panel for Different Values of a/b (E=8000MPa, Dip = 65°) Figure 9.4 Voussoir Beam Method of Span Determination (Beer et a l , 1982) 239 CHAPTER TEN CONCLUSIONS 10.1 Concluding Remarks The h a n g i n g w a l l a n d f o o t w a l l a t R u t t a n was c o n c l u d e d t o be i n a s t a t e o f r e l a x a t i o n , g i v e n t h e p r e v a i l i n g s t r e s s c o n d i t i o n s a n d s t o p e c o n f i g u r a t i o n . T h i s , c o u p l e d w i t h a f o l i a t e d h a n g i n g w a l l , was d e t e r m i n e d t o be t h e d o m i n a n t f a i l u r e m e c h a n i s m . O p t i m u m s t o p e g e o m e t r y was e q u a t e d t o s t o p e s y i e l d i n g l o w e r o b s e r v e d d i l u t i o n . T h e f a c t o r s t h a t d i r e c t l y c o n t r i b u t e d t o i n c r e a s e d w a l l s l o u g h w e r e : - the rock quality of the in d i v i d u a l c r i t i c a l wall contact - the exposed surface area - the rate at which the wall contact was exposed. F i g u r e 8.1 s u m m a r i z e s t h e e m p i r i c a l l y d e r i v e d e x p r e s s i o n s a s q u a n t i f i e d t h r o u g h o b s e r v a t i o n ( 1 3 3 ) r e c o r d e d f o r t h e R u t t a n d a t a b a s e . I t was c o n c l u d e d t h r o u g h m u l t i v a r i a t e a n a l y s e s , t h a t t h e p r e d i c t i v e e x p r e s s i o n s w e r e h i g h l y s i g n i f i c a n t a n d c o r r e l a t i v e t o t h e o b s e r v e d d i l u t i o n s . D i l u t i o n was f o u n d t o be l a r g e l y i n s e n s i t i v e t o t h e 240 f o l l o w i n g f a c t o r s : - the s t o p e s p a n / w i d t h r a t i o - the m i n i n g d e p t h - the method of open s t o p i n g ITH v e r s u s c o n v e n t i o n a l ) - the mine s e q u e n c e (FW-** HW) The p r e d i c t i v e e q u a t i o n s were d e f i n e d f o r the i s o l a t e d , r i b and e c h e l o n c o n f i g u r a t i o n s . G e n e r a l l y , i t was f o u n d t h a t the e c h e l o n g e o m e t r y y i e l d e d the l o w e s t d i l u t i o n (2% l e s s t han i s o l a t e d ) w i t h the r i b s t o p e s e x h i b i t i n g the g r e a t e s t d i l u t i o n (1.5% g r e a t e r t h a n i s o l a t e d ) . F u r t h e r r e s e a r c h s h o u l d be d i r e c t e d i n the f o l l o w i n g a r e a s : 1) A t t e m p t to d e v e l o p a more c o m p r e h e n s i v e p r e d i c t o r f o r the b l a s t i n d u c e d d i l u t i o n . 2) I n s t r u m e n t a t e s t s t o p e i n o r d e r to r e i n f o r c e the o b s e r v a t i o n s made i n t h i s s t u d y . 3) D e v e l o p a l t e r n a t e methods of r e c o r d i n g s t o p e d i l u t i o n t h a t do no t r e l y s o l e l y on v i s u a l a s s e s s m e n t 4) Augment the p r e s e n t d a t a b a s e by o b s e r v a t i o n s made a t o t h e r mine o p e r a t i o n s . In p a r t i c u l a r , a t t e m p t to a s s e s s the e f f e c t of s t o p e i n c l i n a t i o n , s u p p o r t and g r o u n d w a t e r on d i l u t i o n The R u t t a n o p e r a t i o n has a d o p t e d the methods p r o p o s e d i n t h i s t h e s i s . I t has been a b l e to p r e d i c t ' b e t t e r s t o p e d i l u t i o n s , d e s i g n optimum s t o p e spans and to f o r e c a s t b e t t e r the m i n i n g c o s t s i n c u r r e d due to w a l l i n s t a b i l i t y . I t i s 241 s u g g e s t e d t h a t the e m p i r i c a l methods of d e s i g n o u t l i n e d i n t h i s t h e s i s be a t t e m p t e d / c a l i b r a t e d f o r o t h e r o p e r a t i o n s where s i m i l a r f a i l u r e mechan i sms p r e v a i l . I t s h o u l d be n o t e d t h a t the c h a r a c t e r i s t i c s u n i q u e to the R u t t a n o p e r a t i o n be a s s e s s e d p r i o r to e x t e n d i n g the s t u d y to o t h e r o p e r a t i o n s . The a u t h o r ' s c o n t r i b u t i o n to the e x i s t i n g s t a t e of k n o w l e d g e c o n c e r n i n g open s t o p e d e s i g n i s i n t he e m p i r i c a l a p p r o a c h to the d e v e l o p m e n t o f a d e s i g n m e t h o d o l o g y . T h a t r e l a t i o n s h i p b e i n g p r i m a r i l y a f u n c t i o n of " e x p o s e d s u r f a c e a r e a , e x p o s u r e r a t e and r o c k mass r a t i n g " . The g o v e r n i n g e q u a t i o n s a r e a p p l i c a b l e f o r the R u t t a n o p e r a t i o n , however the m e t h o d o l o g y i s v a l i d f o r a l l open s t o p i n g o p e r a t i o n s . The a b s o l u t e m a g n i t u d e s of s t o p e d e s i g n a r e e x p r e s s e d i n te rms of d i l u t i o n . T h i s p a r a m e t e r i s d i f f i c u l t t o a s s e s s a c c u r a t e l y , however once c a l i b r a t e d , i t i s a u s e f u l i n d i c a t o r o f i n s t a b i l i t y f o r any mine o p e r a t i o n . To draw t h i s t h e s i s to a c l o s e , the a u t h o r has s e l e c t e d the f o l l o w i n g f r o m T e r z a g h i ( 1939) : "A good t h e o r y i s one t h a t works i n p r a c t i c e . T h e r e i s a t e n d e n c y among the young and I n e x p e r i e n c e d to put b l i n d f a i t h i n f o r m u l a e f o r g e t t i n g t h a t most of them a r e b a s e d on p r e m i s e s w h i c h a r e not a c c u r a t e l y r e p r o d u c e d i n p r a c t i c e , and w h i c h , i n any c a s e , a re f r e q u e n t l y u n a b l e to t a k e i n t o a c c o u n t c o l l a t e r a l d i s t u r b a n c e s w h i c h o n l y o b s e r v a t i o n and e x p e r i e n c e can f o r e s e e and common sense p r o v i d e a g a i n s t " . 242 LIST OF REFERENCES The f o l l o w i n g a r e r e p o r t s , i n t e r - o f f i c e memoranda, and p u b l i s h e d a r t i c l e s t h a t have been g e n e r a t e d by the a u t h o r i n o r d e r t o a c c o m p l i s h the o b j e c t i v e s o f t h i s t h e s i s . T h i s i s f o l l o w e d by a l i s t o f r e f e r e n c e s of a r t i c l e s t h a t were r e l a t e d t o the t h e s i s t o p i c . Internal Reports M i l l e r , H.D.S.M (1982) Underground Rock Mechanics Investigation at the Ruttan Mine. P r o p o s a l , A p r i l , U n i v . B . C . , p p . 7 . P a k a l n i s , R . C . T (1982) Underground Rock Mechanics Investigation at Ruttan Mine-Workscope. I n t e r n a l - r e p o r t , O c t o b e r , U n i v . B . C . , pp . 4. P a k a l n i s , R . C . T (1983) Bitem Operating Manual-Modifications by R.Pakalnis. In t e r na 1-r e p or t , May, U n i v . B . C . , pp.. 160 . P a k a l n i s , R .C .T (1983) P l o t - B i t e . A Post-Processor Program for Bitem. I n t e r n a 1 - r e p o r t , A u g u s t , U n i v . B . C . , pp. 8 0 . P a k a l n i s , R . C . T (1983) CSIRO Overcoring Measurements Conducted At Ruttan:In-Situ Stress Determination , I n t e r n a l - r e p o r t , November , U n i v . B . C . , p p . 120. P a k a l n i s , R . C . T (1984) Geo-Numerical Model: An Aid in Mine Design-Thesis Proposal. I n t e r n a 1 - r e p o r t , A u g u s t , U n i v . B . C . , PP.21 243 P a k a l n i s , R.C.T a n d P o t v i n , Y. ( 1 9 8 5 ) Review of Rock Mass C l a s s i f i c a t i o n S y s t e m s , I n t e r n a l - r e p o r t , F e b r u a r y , U n i v . B.C., p p . 1 4 0 . P a k a l n i s , R.C.T ( 1 9 8 5 ) Comprehensive Research Proposal for The Development of a Geo-Numerical Model as an Aid in Stope D e s i g n - C o m p r e h e n s i v e . , I n t e r n a l - r e p o r t , F e b r u a r y , U n i v . B.C., p p . 3 3 . P a k a l n i s , R.C.T ( 1 9 8 5 ) D i l u t i o n approach to Stope Design-Progress Report, I n t e r n a l - r e p o r t , J u l y , U n i v . B.C., p p . 3 5 . P a k a l n i s , R.C.T. ( 1 9 8 5 ) Rock Characterization-Data C o l l e c t i o n at Ruttan., I n t e r n a l - r e p o r t , May, U n i v . B.C., p p . 6 0 . P a k a l n i s , R.C.T ( 1 9 8 4 ) Influence of Groundwater at Ruttan. I n t e r n a l - r e p o r t , A u g u s t , U n i v . B.C., p p . 21. P a k a l n i s , R.C.T. a n d P o t v i n Y. ( 1 9 8 5 ) Survey of Open Stope and Room and P i l l a r Operators, I n t e r n a l - r e p o r t , D e c e m b e r , 1 9 8 5 , p p . 3 0 . B.A.Sc Thesis Supervised by R.Pakalnis G o l d b e c k B. ( 1 9 8 5 ) Analysis of Stress Changes at S h e r r i t t Gordon's Ruttan Mine, I n t e r n a l - r e p o r t , J a n u a r y , U n i v . B.C., p p . 50 G r e e n D. ( 1 9 8 5 ) P i l l a r Stresses determined by Tributary Area Theory and by Bitem, I n t e r n a l - r e p o r t , A p r i l , U n i v . B.C., pp. 67 M a d s e n P. ( 1 9 8 5 ) The Application of Elementary Beam Theory, F i n i t e Element Analysis and Voussoir Arch Theory to the Design of Underground Openings, I n t e r n a l - r e p o r t , A p r i l , U n i v . B.C., p p . 1 1 0 S e k i F. ( 1 9 8 4 ) Determination of Structural Domains and Design Sectors for the Ruttan Deposit, I n t e r n a 1 - r e p o r t , F e b r u a r y , U n i v . B.C., pp. 50 S i u K.K.M. ( 1 9 8 5 ) D e s c r i p t i o n and Analysis of Common Failure Modes at Ruttan, I n t e r n a l - r e p o r t , A p r i l , U n i v . B.C., pp. 152 244 Published A r t i c l e s Moss A . E . S . , Page C. and P a k a l n i s R . C . T . (1984) Rock Mass C l a s s i f i c a t i o n : A Useful Tool i n Planning Open Stopes, P r o c . AIME F a l l M t g . , D e n v e r pp . 10 P a k a l n i s R . C . T . ( 1984 ) Rock Mass C l a s s i f i c a t i o n Systems:A Tool in Mine Design, Crown P i l l a r D e s i g n Workshop (CIMM), T o r o n t o , O n t a r i o . , pp. 20 P a k a l n i s R . C . T . , M i l l e r H . D . S . , and M a d i l l T . (1985) Development of a Geo-Numerical Model as an Aid in Stope Design, 26 th U.S . Symposium on Rock M e c h a n i c s , A . A . B a l k e m a , B o s t o n p p . 140-148 P a k a l n i s R . C . T . , M i l l e r H . D . S . , and M a d i l l T . (1985) In-Situ Stress Determination at Ruttan Mine, S h e r r i t t Gordon Mines Ltd . , . C I M 8 7 t h A n n u a l G e n e r a l M e e t i n g , V a n c o u v e r , B . C . , A p r i l , p p . 1 8 . P a k a l n i s R . C . T . , M i l l e r H . D . S . , and M a d i l l T . (1985) Open Stope design - A Di l u t i o n Approach, SANGORM Symp. on Rock M e c h a n i c s , R a n d b u r g , S t h . A f r i c a , November , pp . 93-98 I n t e r - o f f i c e Memoranda P a k a l n i s R . C . T . ( 1983 ) Rock Mechanics Study at Rut tan-Progress Report, I n t e r - o f f i c e , U n i v . B . C . , J a n u a r y pp . 5 P a k a l n i s R . C . T . ( 1 9 8 3 ) Modelling the Extraction Sequence , I n t e r - o f f i c e , S h e r r i t t G o r d o n M i n e s , M a r c h , pp . 10 P a k a l n i s R . C . T . (1983) Analysis of S i l l P i l l a r - 20 East L e n s e s , I n t e r - o f f i c e , . S h e r r i t t G o r d o n M i n e s , A p r i l , pp. 22 P a k a l n i s R . C . T . ( 1983 ) Rock Mass C l a s s i f i c a t i o n at Ruttan M i n e , I n t e r - o f f i c e , S h e r r i t t G o r d o n M i n e s , k J u l y , pp. 10 P a k a l n i s R . C . T . ( 1983 ) Mechanism of Failure at Ruttan Mine, I n , t e r - o f f i c e , S h e r r i t t G o r d o n M i n e s , J u l y , pp. 10 P a k a l n i s R . C . T . ( 1983 ) Monitoring of Further 12B F/W Slough on the 260m L e v e l , I n t e r - o f f i c e , S h e r r i t t Gordon M i n e s , J u l y , pp. 10 P a k a l n i s R . C . T . (1983) S t a b i l i t y of P i l l a r X-Cut 14D and U/W Drive on 370m Level , In t e r - o f f i c e , S h e r r i t t Go rdon M i n e s , Ju ly , j p p . 3 P a k a l n i s R . C . T . ( 1983 ) Degree of Water Entering 320-12B 245 S t o p e , I n t e r - o f f i c e , S h e r r i t t G o r d o n M i n e s , J u l y , pp. 2 P a k a l n i s R . C . T . (1983 ) Mining Sequence/ Support Methods / Monitoring Program, I n te r -o f f i c e , S h e r r i t t Gordon M i n e s , J u l y , p p . 14 P a k a l n i s R . C . T . (1983) Proposed Core Logging Format Modification/ Back-analysis of Slough in 370m 14D Stope, I n t e r - o f f i c e , S h e r r i t t Go rdon M i n e s , O c t o b e r , pp . 10 P a k a l n i s R . C . T . (1984) Failed P i l l a r Concept at Ruttan, I n t e r - o f f i c e , S h e r r i t t G o r d o n M i n e s , J a n u a r y , p p . 10 P a k a l n i s R . C . T . (1984) Numerical Modelling of Mining 320-12BE(Stope) on the 320m Level, I n t e r - o f f i c e , S h e r r i t t G o r d o n M i n e s , M a r c h , p p . 1 0 P a k a l n i s R . C . T . (1984) S t a b i l i t y Analysis of S i l l P i l l a r Separating Upper and Lower Mine/ Rock Strengths at Ruttan/ Drawpoint S t a b i l i t y , I n t e r - o f f i c e , S h e r r i t t Go rdon M i n e s , A p r i l , p p . 30 P a k a l n i s R . C . 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Case Examples of Underground Mine S t a b i l i t y Investigations, S t a b i l i t y in Underground Mining, AIME, New York, pp. 829-846 Mathews, K.E., Hoek, E. , Wylie, D.C. and Stewart, S. (1981). Prediction of Stable Excavation Spans for Mining at Depths Below 1000 Meters i n Hard Rock, CANMET Dept. of Energy, Mines and Resources, Canada, DSS Se r i a l No. 0sQ80-0081DSS F i l e No. 17SQ 23440-0-9020. pp. 80. Mi l l e r H.D.S.,Potts E.L., and Szeki A.(1976).In-Situ Stress Measurements in Halite in Chesire, Potash in North Yorkshire, and Slate at Dinorwic,Part II, Proc. Rock Engineering, University of Newcastle-upon-Tyne, England, pp. 257-272 . Morrison, R.G.K. (1976). A Philosophy of Ground Control, published by Dept. Min. and Metal. Engng., McGlll Univ., Montreal, pp. 125-160 Moss, A.E.S and Niemi B. (1985).Investigation into Mining of a Main Crown P i l l a r , D i s t r i c t Three Meeting, September, pp.19. Nicholas, D. (1981)Method Selection - A Numerical Approach, Design and Operation of Caving and Sublevel Stoping Mines, eds. D. Stewart, AIME, New York, pp. 39-54. 249 Ontario Ministry of Labour (1985). Pr o v i n c i a l Inquiry Into Ground Control and Emergency Preparedness in Ontario Mines, Report prepared by 1) Steffen, Robertson and Kirsten and 2) Golder and Assoc., Ontario Ministry of Labour, Sudbury, Ontario. Page, C.H., Brenner, R.G. (1983). S t a b i l i t y of Large Open Stopes in Weak Rock, S t a b i l i t y in Underground Mining, AIME, New York, pp. 336-356 Pariseau, W.G., Fowler, M.E. and Johnson, J.C. (1984). Geomechanics of the Carr Fork Mine Test Stope, Geomechanics Applications in Underground Hardrock Mining, SME/AIME, New York, pp. 3-38 Parker J. (1973).Practical Rock Mechanics for Miners, EMJ, June,pp.78. Potts, E.L.J., Szeki, A., Watson, S.H., Mottahed, P. (1979). The Evaluation of the Design C r i t e r i a for an Underground Roof Strata Considered as a Linear Arch Structure, I n t l . congress on Rock Mech., Proc. 4th, Vol.2, Montreaux, Suisse. Potvin, Y. and Miller,H.D.S (1985). P i l l a r Design Methodology, Presented at AGM-CIM,Vaneouver,B.C. Rotzien, J. and M i l l e r H.D.S (1985). Report on In-Situ Stress Measurement at McLellan Mine, Internal Report, University of B r i t i s h Columbia pp. 150. Smith J.D. (1976-1979). Progress Report Ruttan Underground Rock Mechanics Study, Internal Reports. Sherritt Gordon Mines Speakman, D., Chornoby,P.,Holmes,G. and Haystead B. ( 1976 ). Geology of the Ruttan Deposit, Internal Report - Sherritt Gordon Mines, pp.25. Spiegiel, M. (1972).Theory and Problems of Probability and S t a t i s t i c s , Schaum's Outline Series, McGraw H i l l Co., pp.72. St. John, CM., Christianson, M., Petersen, D.L. (1980). Evalustion of Mine Parameters for Copper-Nickel Deposits of Northern Minnesota, U.S. Bureau of Mines, Open Fi l e Report No. 10-80, pp.87 Terzaghi K. (1943). Theoretical S o i l Mechanics, John Wiley, New York, New York, pp. 510. Vasey, J. (1983). Design and to High Horizontal Stresses, AIME, New York, pp.428-449 Support of Excavations subjected S t a b i l i t y in Underground Mining, Vennard, J.K and Street, R . L . (1975). Elementary F l u i d Mechanics, John Wiley & Sons Inc., Toronto* pp.326-327. 2 5 0 Wang, F.D., Danek, L.A. and Sun, M.C. (1971). S t a b i l i t y Analysis of Underground Openings Using a Coulomb Failure C r i t e r i a , Trans. Soc. Mining Eng., AIME, Vol. 250 pp. 317-321. Wardle, L.J. (1980). Three-DImensional Boundary Element Program for Mining Applications : MIN3D2 (3DBELM), CSIRO Publication, Technical report No. 116, pp. 17. Watson J.O. and Cowling R. (1985). Application of Three Dimensional Boundary Element Methods to Modelling of Large Mining Excavations at Depth, Paper presented to 5th Int. Conf. on Numerical Meth. in Geomech., Nagoya. Worotnicki, G. and Walton, R.J (1976).Hollow Inclusion Gauges for the Determination of Rock Stress In-Situ, Proc. ISRM Symp. on Investigation of Stress in Rock and Advances in Stress Measurement, Sydney, pp. 1-8. Wright, D.F. (1980). Roof Control Through Beam Action and Arching , SHE Mining Engineering Handbook, AIME New York, Vol. 13, pp.80-85. APPENDIX I QUESTIONAIRE 25 STOPE k PILLAR DIKENSIONS - Indicate the stope and p i l l a r dimensions on the sketch or on the "STOPE CHARACTERIZATION" Table (next page). ROOM 4 PILLAR MINTNf*. ROCK KECHANIC DATA BASE Indicate with an "x" which of the following parameters have been estimated at your mlnei s5 to to : u w u. o to Unit Weight *" El a s t i c Hod u Poisson's Ratio •> In-Situ Measurement Photo-Elastic Model Computer Modelling Compress. Strength o° Tensile Strength o" T r i a x i a l Strength o ID" Shear Strength t-Failure C r i t e r i o n R Q D N C I C S I R Laubscher Structural Mapping Multi-Wire Extenson. Boroscope Observ. Compression Pad Closure Station Levelling Survey Station Piezometer STOPE CHARACTERIZATION MINING METHOD ## STOPE PLUNGE DEPTH FOOTWALL HANGINCWALL ORE OPENING PILLAR STOPE HEICTH % of DILUTION strength 1 fracture spacing joints condition strength fracture spacing joints condition strength fracture spacing joints condition ** X. •»> T l X - o • J i : c width "W," JZ SP ** L i s t individual stopes ROCK STRENGTH - Indicated by uniaxial compressive strength or as follows: . WEAKi 6000 p s i (4) . MODERATEi£000 - 15000 p s i (7) . STRONCi 15000 p s i (12-15) FRACTURE SPACING Fracture/m % RQD Very Closei 16 (9) . o - 20 Closei 10 - 16 (17) 20 - 1*0 Wldei 3-10 (32) i»o - 70 Very Wldei 3 (43-50) 70 - 100 GROUNDWATER Dry (10) ( > Refers to RMR Rating Equivalent. JOINTS CONDITION WEAKi Clean j o i n t with a smooth surface or f i l l with mate-r i a l whose strength i s less than rock mass strength (3) MODERATEi Clean joint wlyh rough surface (12) STRONCi Joint i s f i l l e d with a material that i s equal to or stronger than rock mass strength (20-25) APPENDIX II RMR SYSTEM OF CLASSIFICATION 256 E x c e r p t from Review of Rock Mass C l a s s i f i c a t i o n Systems P a k a l n i s ( 1 9 8 5 ) 3 . 1 . DEERE'S ROCK QUALITY DESIGNATION The concept of the rock quality designation was proposed in 1964 by Deere (1975) and was o r i g i n a l l y based on fourteen tunnels. It was subsequently expanded and incorporated by numerous c l a s s i f i c a t i o n schemes. (Einstein, 1979). The RQD i s a quantitative index based on a core recovery procedure in which the core recovery i s determined incorporating only those pieces of hard, sound core which are 100 mm or greater in length. Shorter lengths are ignored, Figure 14. It can be determined from the following expression:-RQD(%) = 100 x ^length of core in pieces 100 mm or longer length of core run Core of at least 50 mm in diameter should be used. If core of lesser or greater diameters i s to be used, the nominal length of 100 mm should be altered to correspond to two times the core diameter. The International Society of Rock Mechanics recommends that the length of individual core pieces should be assessed along the centre line of the core, so that the di s c o n t i n u i t i e s that hapen to p a r a l l e l the d r i l l hole w i l l not unduly penalise the RQD values of an otherwise massive rock mass (Figure 15). It i s important to distinguish between mechanical and natural breaks found in the core. A mechanical break caused by handl ing should not adversely affect the RQD index which is a measure of the i n - s i t u rock q u a l i t y . The mechanical broken core segments should be approximated into a s o l i d unit of core in order to arrive at a r e l i a b l e RQD value. Over consolidated gauge i s treated as having a core length less than 100mm. This i s due to the RQD being a measure of only "hard, sound core." The 257 RQD should be evaluated over an i n t e r v a l general ly not less than .5 m -2 m and i s t y p i c a l l y between 1.5 m - 6 m. Shear zones or extremely weak zones must be delineated for subsequent a n a l y s i s . This value w i l l generally be a function of the intactness of the core. The in t e r v a l evaluated should be of a si m i l a r s t r u c t u r a l design u n i t . The RQD procedure is simple, inexpensive and reproductible. The following r e l a t i o n s h i p e x i s t s between the numerical values of the RQD and the general q u a l i t y of the rock for engineering purposes: RQD ROCK QUALITY > 25 per cent very poor 25 - 50 per cent poor 50 - 75 per cent f a i r 75 - 90 per cent good 90 - 100 per cent very good Core recovery (in) 10 2 2 3 4 S 3 4 6 4 2 5 50 Core recovery • 50/60«83% Core Run" 60" Modified Core recovery (in) 10 4 5 34 ROD (rock quoMy oevgnotion) 0 - 25 25 - 50 50 - 75 75 " 90 9C -100 ROD •34/60«57% FIGURE 14 MODIFIED CORE RECOVERY AS AN INDEX OF ROCK QUALITY (DEERE,1975). 258 FIGURE 15 Recommended method of measuring f r a c t u r e l eng ths : examples of three poss i b l e i n t e r p r e t a t i o n s of the length of core p i e c e s . The cent re l i n e length i s suggested as the most r e a l i s t i c measurement and i s recommended ( a ) . The c y l i n d r i c a l i n t e r p r e t a t i o n (b) would unduly pena l i z e the RQD values of an otherwise massive mass. In order to determine the RQD of rock sur faces a tape i s suspended h o r i z o n t a l l y a long the sur face and o r i en ted at a r i g h t angle to the dominant f r a c t u r e d i r e c t i o n . 259 In t h i s way, an assessment of the true fracture spacing i s obtained. Two metre lengths are assessed. (Laubscher, 1972). The R.Q.D. is a core recovery technique that can be applied to rock surfaces provided the following points are observed: a) Experience in determining the R.Q.D.of core i s necessary before attempting the R.Q.D. assessments of rock surfaces. b) Do not be misled by bl a s t i n g f r a c t u r e s . c) Weaker bedding planes do not necessar i l y break when cored. d) Where a j o i n t ( s l i p ) face forms the sid e w a l l , assess the opposite w a l l . e) Shear zones greater than two metres in width must be c l a s s i f i e d separately. The c o r r e l a t i o n between core R.Q.D. and rock surface R.Q.D. wi 11 be obtained by d r i l l i n g boreholes p a r a l l e l to excavations. This wll also give c o r r e l a t i o n between the other items. Barton (1983) suggests the following r e l a t i o n s h i p : - When borehole data i s unavailable, RQD can be estimated from the number of j o i n t s per unit volume, where the number of j o i n t s per meter for each j o i n t are added together. A simple r e l a t i o n can be used to convert t h i s number of j o i n t s to RQD. For the resu l t s of a clay free rock mass: RQD = 115 - 3.3 Jv (approximate) 3 where Jv i s the to t a l number of j o i n t per m . (RQD=100 for Jv = 4.5). P r i e s t and Hudson (1976) developed a chart showing the c o r r e l a t i o n that exists between RQD and j o i n t spacing, Figure 16. 2 6 0 MEAN DISCONTINUITY SPACING FIGURE 16 THEORETICAL RELATIONSHIP BETWEEN RQD AND DISCONTINUING SPACING. (PRIEST AND HUDSON, 1976) 3.3 GEOMECHANICS CLASSIFICATION (RMR) T h i s c l a s s i f i c a t i o n s y s t em was d e v e l o p e d f o r t h e Sou th A f r i c a n C o u n c i l f o r S c i e n t i f i c and I n d u s t r i a l R e s e a r c h (CSIR) by B i e n i a w s k i i n 1973 . I t employs f i v e p a r a m e t e r s : a ) t h e u n i a x i a l c o m p r e s s i v e s t r e n g t h o f i n t a c t r o c k m a t e r i a l b) r ock q u a l i t y d e s i g n a t i o n c ) s p a c i n g o f f r a c t u r e s d) c o n d i t i o n o f f r a c t u r e s i . e . f r i c t i o n a l p r o p e r t i e s and c o n t i n u i t y e) g round w a t e r c o n d i t i o n s Each o f t h e s e p a r a m e t e r s i s g i v e n an i m p o r t a n c e r a t i n g f o r a p a r t i c u l a r s i t u a t i o n . The r a t i n g s were d e t e r m i n e d f rom 49 c a s e h i s t o r i e s i n v e s t i g a t e d by B i e n i a w s k i (1984) and augmented by t h e work o f Wickham e t a l ( 1 9 7 4 ) . The t o t a l r a t i n g i s an i n d i c a t o r o r r o ck q u a l i t y and r ange s f rom l e s s than 25% (wo r s t rock c o n d i t i o n s ) t o 100% ( b e s t r o ck c o n d i t i o n s ) . The r a t i n g i s s u b s e q u e n t l y a d j u s t e d t o a c c o u n t f o r t h e i n f l u e n c e o f s t r u c t u r a l o r i e n t a t i o n on s t a b i l i t y . T h i s a d j u s t e d r a t i n g i s used t o c l a s s i f y t h e rock i n t o one o f f i v e c l a s s e s wh i c h e m p i r i c a l l y can be r e l a t e d t o t h e s t a n d - u p t ime o f u n s u p p o r t e d o p e n i n g s , s u p p o r t r e q u i r e m e n t s , and r o c k mass s t r e n g t h i n d i c e s . The c l a s s i f i c a t i o n a s s e s s e s t h e t y p i c a l r a t h e r t h a n t h e wo r s t r ock mass c o n d i t i o n s . 261 3.3.1 PARAMETERS 3 . 3 . 1 . 1 . UNIAXIAL COMPRESSIVE STRENGTH OF INTACT ROCK MATERIAL The intact rock strength is the average uniaxial compressive strength of the rock. The strength of the rock material constitutes the highest strength limit of the rock mass for a given confining pressure. The rock mass strength will consequently be lower than the intact rock strength due to alteration, ground water and the presence of discontinuities. A number of strength classifications have been proposed and are compared in Table 12. The RMR system employs the rock strength groupings as derived by Deere (Table 13). Typical rock strengths are summarized in Table 14. TABLE 12 C l a s s i f i c a t i o n s f o r Strength o f Intact Rock (B ien iawsk i , 1973) 05 07 , I I I I I I J 4 5 ( 7 1 . _l • ' ' i i i I 100 20 30 40 50 70 . i i I I i i i i I 300 300 400 700 i i i i i i Very weak Strong Very ilrong Very »tik Eitremely low strength Very to» itrength tow itrength Medium itrength High itrength Very high itrength Weak Moderately weak Moderately ilrong Strong Very ilrong Enremely Wong Very low tow Medium High Very high Eii'fmely high •trenpth mengih itrength. itrength ftrcngth itrength Vrn tvofi Hard Ver> hard Eitremely hard rock Soft reck rock rock rock Very ten* itrength Low itrength Medium mengih H>gh strength Very high mengih H.<h Very Very »°» Low itrength Moderate Medium rut's Co.iet I9W Deere and Miller 1966 Geological Society 1970 Qrnth .nj Franklin 1972 Jenmngi Btcniawiki 1973 ISRM 1971* I I I I I | 01 07 1 ) 4 I I I I I I 5 ( 7 1 1 10 I 1 — I — I I I I 1 1 — 20 JO 40 30 70 1 100 — i 1 — i — i — n 200 30C '00 700 U n i a x i a l c o m p r e s s i v e s t r e n g t h . M P a 2 6 2 TABLE 13 BIENIAWSKI CLASSIFICATION FOR INTACT ROCK STRENGTH (BIENIAWSKI,1973) U n i a x i a l D e s c r i p t i o n c o m p r e s s i v e Examples o f r o c k strength,MPa t y p e s Very low strength 1 - 25 Chalk, rocksalt Low strength 25 - 50 Coal, s i l t s t o n e , s c h i s t Medium strength 50 - 100 Sandstone, s l a t e , shale High strength 100 - 200 Marble, granite, gneiss Very high strength > 200 Quartzite, d l e r i t e , gabbro, b a s a l t . 263 TABLE 14 STRENGTH DATA FOR INTACT ROCK (BIENIAWSKI, 1973) Uni axi al compressive strength MPa Rock Type Min. Max Mean Chalk 1,1 1,8 1,5 Rocksalt 15 29 22,0 Coal 13 41 31,6 Sil t s t o n e 25 38 32,0 Schist 31 70 43,1 Slate 33 150 70,0 Shale 35 172 95,6 Sandstone 40 179 95,9 Mudstone 52 152 99,3 Marble 60 140 112,5 Limestone 69 180 121,8 Dolomite 83 165 126,3 Andesi te 127 138 128,5 Granite 153 233 183,4 Gnei ss 159 256 195,0 Basalt 163 359 252,7 Quartzite 200 304 252,0 Dolerite 227 319 230,3 Gabbro 290 326 298,0 Banded ironstone 425 475 450,0 Chert 587 683 635,0 The reasons for these groupings (Table 13) are as follows: - the c l a s s i f i c a t i o n i s widely recognized throughout the world - groupings are p r a c t i c a l and r e a l i s t i c - easy to remember It must be noted that a value of 1 MPa i s taken as the lowest strength l i m i t for 264 rock materials and consequently defines the d i v i s i o n between s o i l and rock. Furthermore, the terms of desc r i p t i o n such as low, medium or high strength are preferred to weak or strong, thus avoiding ambiguity when dealing with weathered rocks. No d i v i s i o n s are given for rock strengths less than 25 MPa other than being c l a s s i f e d as having a very low strength. The reason for t h i s i s that rocks e x h i b i t i n g intact strengths under 25 MPa do not behave d r a s t i c a l l y d i f f e r e n t and therefore are grouped as a single u n i t . The uniaxial compressive strength, (UCS), can be determined by laboratory techniques or in the f i e l d by use of the point load apparatus. Bieniawski (1975) had determined that the point load derived UCS i s within 20% of the laboratory derived value. It i s recommended to use laboratory procedures to evaluate rock strengths whose values are less than 25 MPa. 3.3.1.2 ROCK QUALITY DESIGNATION (RQD) Refer to Deere's d e f i n i t i o n , Section 3.1 3.3.1.3 JOINT SPACING The term j o i n t means a l l d i s c o n t i n u i t i e s which may be t e c h n i c a l l y j o i n t s , f a u l t s , bedding planes or other surfaces of weakness. The spacing of j o i n t s i s the mean distance between the planes of weakness in the rock mass in the d i r e c t i o n perpendicular to the j o i n t planes. The presence of j o i n t s reduces the strength of a rock mass and the j o i n t spacing governs the degree of the reduction. The c l a s s i f i c a t i o n of j o i n t s based on spacing is derived a f t e r Deere as follows: Descr ip t ion Spacing of J o i n t s Rock Mass Designation very wide > 3 m s o l i d wide 1 - 3 m massive moderately close 0.3 - 1 m blocky/seamy close 50 - 300 mm fractured very close > 50 mm crushed 265 Bieniawski states that the data on spacing of joints must be obtained from a joint survey, for each joint set, and not from borehole logs. It is d i f f i c u l t to distinguish between joint sets from d r i l l cores; however, where possible one should attempt to determine a mean joint spacing. It is our experience (Sherritt Gordon Mines) that where site information is restricted to boreholes, a good estimate of joint spacing is derived as follows: 1) choose a borehole interval that exhibits similar rock mass characteristics i.e. RQD, rock type, frequency of fractures, normally between 1.5 to 6 m. joint spacing =logged interval number of joints 2) an alternative is to group each joint according to its dip, i.e. 0 - 30°, 30 -60 °, 60 - 90°, and determine a spacing for each. Otherwise relative values are obtained for vertical or near-vertical d r i l l holes. Joints must also be contim-ous i f they are to be included within the definition of "joint spacing". A joint is continuous i f i t s length is greater than one diameter of the excavation or three meters. It is also continuous i f i t is less than three meters but extends from one joint to another, i.e. define blocks. The RMR system of importance ratings for joint spacing apply to rock masses having three joint sets. The rating is conservative i f only two sets exist. (Bieniawski, 1984). Bieniawski (1984) has recently applied the work of Priest and Hudson (1976) into developing a single rating incorporating The RQD and joint spacing. In either knowing the RQD or joint spacing one is able to arrive at the RMR rating which sums the two parameters. 266 FIGURE 23 CHART FOR CORRELATION BETWEEN RQO AND JOINT SPACING (BIENIAWSKI, 1984) 267 3.3.1.4 JOINT CONDITION Condition of j o i n t s refers to the separation of j o i n t s (distance between j o i n t s u rfaces), continuity and roughness of j o i n t s as well as gouge material. If gouge i s present, i t s type and thickness should be s p e c i f i e d . Tight j o i n t s with rough surfaces and no gouge have a high strength. Continuous, smooth open j o i n t s w i l l f a c i l i t a t e u n r e s t r i c t e d in flow of ground water, thus d i c t a t i n g a lower mass r a t i n g . Bieniawski proposed the following d e s c r i p t i o n s : ROUGHNESS - very rough: near v e r t i c a l steps and ridges occur on the d i s c o n t i n u i t y surface. - rough: some ridge and side-angle steps are evident, a s p e r i t i e s are c l e a r l y v i s i b l e , and j o i n t surfaces feel very abrasive/ - s l i g h t l y rough: A s p e r i t i e s on j o i n t surfaces are dist i n g u i s h a b l e and can be f e l t . - smooth: surface appears smooth and f e e l s so to the touch. - s l i c k e n sided: visual evidence of p o l i s h i n g e x i s t s . SEPARATION BETWEEN JOINT WALLS - very tight < 0.1 mm - t i g h t 0.1 - 0.5 mm - moderately open 0.5 - 2.5 mm - open 2.5 - 10 mm very wide 10 - 25 mm (If separation exceeds 25 mm the j o i n t should be treated as a major d i s c o n t i n u i t y . ) 268 WEATHERING a) . Unweathered. No v i s i b l e signs are noted of weathering; rock fresh; c r y s t a l s b r i g h t . b) . S l i g h t l y weathered rock. D i s c o n t i n u i t i e s are stained or discolored and may contain a thin f i 11 ing of alt e r e d m a t e r i a l . Discoloration may extend into the rock from the d i s c o n t i n u i t y surfaces to a distance of up to 20 per cent of the d i s c o n t i n u i t y spacing. c) . Moderately weathered rock. S l i g h t d i s c o l o r a t i o n extends throughout the rock, and the rock material i s p a r t l y f r i a b l e . The o r i g i n a l texture of the rock has mainly been preserved, but separation of the grains has occurred, e ) . Completely weathered rock . The rock i s t o t a l l y d iscolored and decomposed and in a f r i a b l e condition. The external appearance i s that of s o i l . I n t e r n a l l y , the rock texture i s partly preserved, but grains have completely separated. 3.3.1 .5 GROUND WATER CONDITIONS Ground water i s known to have an important e f f e c t on the behaviour of jointed rock masses. The rate of i nf 1 ow of ground water greatly a f f e c t s the stabi 1 i t y of tunnels. A value of 10 i s employed for a completely dewatered s i t u a t i o n whereas a rock mass rating of 0 indicates severe water problems. 3.3.2 APPLICATIONS The above parameters are incorporated into table 15. The c l a s s i f i c a t i o n parameters discussed previously are to be provided by the engineering geologist from his measurements conducted in the f i e l d . One complete set of data i s needed for each s t r u c t u r a l region as encountered along the tunnel route. A st r u c t u r a l region i s defined as a zone in which s i m i l a r geotechnical s t a b i l i t y can be expected. The geologist should supply any additional information which he considers useful and relevant. A number of observations should be made with respect to Table 15. It w i l l be 2 6 9 noted that rock parameters and rock masses are grouped into f i v e c l a s s e s . This i s considered s u f f i c i e n t to provide for meaningful d i s c r i m i n a t i o n 1n a l l the parameters. More classes could be d i f f i c u l t to work with while fewer classes may not o f f e r s u f f i c i e n t l y clear d i s t i n c t i o n s . In applying various parameters to a rock mass c l a s s i f i c a t i o n , i t i s necessary to note that d i f f e r e n t parameters are not equally important for the overall c l a s s i f i c a t i o n of a rock mass. Accordingly, importance ratings are also given in Table 15 for each parameter and i t s s u b d i v i s i o n . These ratings are p a r t l y derived from a study by Wickham et al (1974). Two points should be noted in connection with these r a t i n g s . F i r s t l y , the ratings given for j o i n t spacings apply to rock masses having three sets of j o i n t s . Thus, when only one or two sets of j o i n t s are present, a conservative assessment i s obtained. Secondly, some d i f f i c u l t i e s may be experienced in deciding whether s t r i k e and dip orie n t a t i o n s are favourable or not in a given tunnel. (Refer to Parameter B, RSR). Once the importance ratings of the c l a s s i f i c a t i o n parameters are added, giving the t o t a l r a t i n g for the rock mass, i . e . i t s s t r u c t u r a l region under consideration. Note that the higher the t o t a l r a t i n g , the better the rock mass conditions. The Geomechanics c l a s s i f i c a t i o n has established i t s e l f as a useful and v e r s a t i l e technique for assessing rock mass conditions on engineering p r o j e c t s . The main app l i c a t i o n s of rock mass c l a s s i f i c a t i o n s have t r a d i t i o n a l ly been in tunnell ing. The RMR system has been employed by various authors on rock slopes ( Steffen, 1976), dam foundations (Bieniawski for 1976) ground r i p p a b i l i t y ( K i r s t e n , 1982) coal mining (Bieniawski, 1983) and in metal mining (Laubscher, 1978). A. Classification parameter* and their rating! PAR I V E T E R RANGCS OP VALUES 1 Strength' Ol miaei rock material Pomi-toad strength <nd«a > 10 MPa 4 - 10 MPa 2 • 4 MPa i * 2 MPa For inn low range • uflijoal comprea-•ive teat is preferred Umaxal Compressive Strength >2S0 MPa 100 - 290 MPa SO -100 MPa 2S • 90 MPa 5-25 MPa 1-5 MPa <1 MPa Rating IS 12 7 4 2 i 0 2 Onll corf quality RQO 90%-100% 75*-90% 50% -75% 25%. 50* < 25S Rating 20 17 13 8 3 3 Soacmg of discontinuities >2m 0.8 - 2 m 200-000 mm 60-200 mm 60 fif Rating 20 15 10 8 5 4 Condition ol diKonitnuit'ta Very rough surface*. Not continuout No separation Unweathered wall rock Slightly rough surfaces Separation < i mm Slightly weathered walls Slightly rough aurlaeee. Seperetion < 1 mm Highly weathered walla Sitctanaided aurtecea OR Gouge < 5 mm then OR Separation 1-5 mm. Soft gouge > 5mm thick O R Separation 5 mm. Continout Rating 30 25 20 10 0 S Ground ••tar inflow per 10 m tunnel length None <to tittes/min 10-25 litres/mm 25-125 Mret/mifl > 125 |On« •*••# [W •>!•<•• lt'»t» 0 0.0-0.1 0.1-0.2 0.2-0.5 ^0.5 General conditions Completely dry Oamp Wet Dripping Flowing Rating 1» to 7 4 0 B. Rating adjustment Tor discontinuity orientation* Striht mo dip Ofiantaliont of (Ojnti V.ry favourabl. Favour ao* !•> UnfavouraoM Vary unfavouraor. Tunn.la 0 -2 •5 -10 -12 Riling* Fo.n0.Kons 0 -2 •7 -15 -25 Sloe.1 0 •i -25 •SO 40 C. Rock mass classes determined from total ratings Rating 100—81 •0—01 00—41 e a — 21 < 20 Class No 1 II III IV V Description Very good rock Good rock Fair rock Poor rock Very poor rock TABLE 15 GEOMECHANICAL CLASSIFICATION SYSTEM 271 3.3.2.1. SUPPORT, ACTIVE SPAN The classification has been applied to highway, railroad and water conveyance tunnels as well as to underground caverns for hydroelectric schemes. A total of 49 case histories were compi led which served as the basis for preparing the span versus stand-up time diagram outlined below in Figure 24. STAND-UP TIME, hr FIGURE 24 GEOMECHANICS CLASSIFICATIONS - Output for mining and tunnelling. Black dots represent mining cases; squares are tunnelling cases. The contour lines are limits of applicability (Bieniawski - 1983) The above figure gives a relationship between the stand-up time and the roof span for various mass ratings. Span is defined as the distance between the d r i f t wal Is or distance from the support to the face i f this is less than tunnel width. Example: 1) Roof strata rating of RMR = 35 means the maximum unsupported span possible in this rock is 5.2 m, however, i t wi 11 stand unsupportd only for four hours and will subsequently collapse (Figure 24). In order to ensure long term s t a b i l i t y , support along the length of the tunnel should be placed. A roof span of 1.5 m and an RMR = 35% will stand indefinitely. 2). A tunnel 272 required to be 10m wide and which has an RMR = 50%: It will stay open for six days unsupported; by placing support, (Table 16), at less than 3m intervals i t will remain stable indefinitely. Note that the active span is the distance from the support to the face since i t is less than the tunnel width. Permanent support recommendations are given in Table 16. TABLE 16 RMR GUIDE FOR EXCAVATION AND SUPPORT IN ROCK TUNNELS (BIENIAWSKI. 1984) Rock m m class Support Rockbollt (30 mm diL. fully bonded) Shotcrete 1. Very good rock R M R : 81-100 2. G o o d rock R M R : 61-80 3. Fair rock R M R : 41-60 4. Poor rock R M R : 21-40 3. V e n poor rock R M R : <20 Full face: 3 m ad ranee Ful l face. 1.0-1.5m advance; Complete support 20 m from face T o p heading and bench: 1.3-3 m advance in top heading; Commence support after each blast; Complete support 10 m from fact Top heading and bench: l .0- l .5m advance in top heading; Install support concurrently with excavation-10 m from face Multiple drifts: 0.5-1.3m advance in top beading; Install support concurrently with eicavation; shotcrete as soon aa possible after blasting Generally no support required except for occasional spot bolting Locally boils tn crown 3 m long, ipaced 2.5 m with occasional wire mesh Systematic bolts 4 m long, ipaced 1.5m-2m in cro«n and walls »nh wire mcih in crown Systematic bolts 4-3 m long, spaced 1-1.5m in cro»n and walls with wire mesh Systematic bolts 5-6 m long, spaced 1-1.3m in crown and walls with wire mesh. Boll invert 30 mm tn crown where required 50-100mm in crown and 30 mm in sides 100-150 mm in crown and 100mm in sides 150-200 mm in crown 150mm in sides and 50 mm on face Light ribs spaced 1 5 m *here re-quired Medium to heavy nos spaced 0 75 m with steel lagging and forepoling if required. Close insert 273 3 . 3 . 2 . 2 . ROCK LOAD Una. from Pennsylvania State (Bieniawski, 1984) had correlated support load to the RMR index. The rock load height i s given by: ht = 100-RMR B 100 Where: ht = rock load height (m) RMR = rock mass r a t i n g B = tunnel width (m) The above r e l a t i o n s h i p i s presented in Figure 25 S P A N , m FIGURE 25 VARIATIONS OF ROCK LOAD WITH ROOF SPAN FOR DIFFERENT RMR VALUES (BIENIAWSKI, 1984) 274 3 .3 .2 .3 MODULUS OF DEFORMATION The Geomechanics C l a s s i f i c a t i o n was found to be a useful method of estimating the i n - s i t u deformabi1ity of rock masses (Bieniawski, 1978). This i s demonstrated by Figure 26, whereby the following c o r r e l a t i o n was obtained: E t J = 2 x RMR - 100 (Cor r e l a t i o n c o e f f i c i e n t = 0.96) M where E is the in s i t u modulus of deformation in GPa. M The above c o r r e l a t i o n was derived on the basis of 22 case h i s t o r i e s involving a wide range of in s i t u tests conducted in various parts of the world. The accuracy of the modulus prediction by the Geomechanics Classification i s within 20% (Bieniawski, 1978) which i s quite acceptable for rock engineering purposes. Serafim and Pereira (Bieniawski, 1984) extended the above r e l a t i o n s h i p between E,. and RMR to cover lower values of E,. by adopting a l o g - l i n e a r form: M M _ 1Q(RMR - 10)/40 M This was shown to give an improved f i t to the lower values of modulus in the range 1 - 1 0 GPa (Figure 26) O 10 2 0 30 4 0 SO ' 6 0 70 6 0 9 0 100 G E O M E C H A N I C S R O C K M A S S R A T I N G ( R M R ) FIGURE 26 CORRELATION BETWEEN THE IN SITU MODULUS OF DEFORMATION AND RMR. (BIENIAWSKI, 1984) 275 3.3.2.4. ROCK MASS STRENGTH Serafim and Pereira (1983) u t i l i z e d Bieniawski's (1979) RMR system to estimate the rock mass cohesive and f r i c t i o n a l p r o p e r t i e s . This was determined through r e l a t i n g the in t a c t strength properties to the mass properties by adjusting for j o i n t condition and ground water. The roughest unweathered j o i n t s under dry conditions were assessed a mass f r i c t i o n angle (^-) of 45°. Flowing water caused an e f f e c t i v e reduction of 8° on - and values for gouge-f i l l e d d i s c o n t i n u i t i e s were put as low as 10°. The following summarizes the relat i o n s h i p between the shear strength parameters and RMR: Class No 1 II III Average stand-up time 10yearsfor 15 mspan 6 months forB m span 1 week for 5 m span Cohesion ol the rock mass > 400 kPa 300 - 400 kPa 200 - 300 kPa Friction angle of the rock mass < 45° 35" - 45* 25* - 35* Class No IV V Average stand-up time 10 hours for 2.5 m span 30 minutes tor 1 m span Cohesion of the rock mass 100 - 200 kPa < 100 kPa Friction angle of me rock mass 15' - 25* < 15' 3 . 3 . 3 . LIMITATIONS The Geomechanics C l a s s i f i c a t i o n i s a means of i d e n t i f y i n g the engineering parameters needed to design safe and e f f i c i e n t mine openings. RMR i s r e l a t i v e l y simple to use and repeatable The Geomechanics C l a s s i f i c a t i o n does not account for the v i r g i n stresses which can have an influence on the condition of d i s c o n t i n u i t i e s by maintaining them under compression or tensions. (Mathews, 1981) 2 7 6 The C l a s s i f i c a t i o n scheme as proposed by Bieniawski i s arranged with succesive reductions of roughness as weathering or gouge f i l l i n g increases. These two processes are not necessarily related. (Barton, 1983) The strength of the j o i n t s in the ground mass i s one of the most important parameters contributing to the s t a b i l i t y of a tunnel. In the geomechanics system, t h i s parameter i s almost ignored in that the t o t a l r a ting is r e l a t i v e l y i n s e n s i t i v e to the j o i n t condition. A d i f f e r e n c e of 15 points in the j o i n t condition r a t i n g out of a tot a l of 25 should represent a major d i f f e r e n c e in the stabi 1 i t y of the tunnel. However, the j o i n t condition r a t i n g can change by as much as 15 points without changing the overall rock mass c l a s s . The i n s e n s i t i v i t y i s p a r t l y due to the summation p r i n c i p l e on which the system i s based. (K i r s t e n , 1983) Bieniawski over-emphaizes j o i n t spacing by employing both an RQD and a j o i n t spacing r a t i n g . Rock q u a l i t y and j o i n t spacing together comprise a measure of block s i z e . By making allowance for these parameters, an u n j u s t i f i e d importance i s assigned to block size compared to, for example, j o i n t strength. This i s the case p a r t i c u l a r l y in view of the f a c t that together, rock qual i t y and j o i n t spacing represent ratings between two and three times larger than that of any one of the other parameters over most of t h e i r respective ranges. (Kirsten, 1983) The RMR was based i n i t i a l l y on Lauffer (1958) which i s generally acknowledged to be excessively conservative. In best q u a l i t i e s of a rock mass, i t i s extremely conservative in terms of stand-up time. The RMR system cannot be employed in the design of structures in rocks containing swelling materials, i . e . shales ( K i r s t e n , 1983) 

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