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UBC Theses and Dissertations

Geotechnical design of the McLellan Mine, Lynn Lake, Manitoba Rotzien, Joey Lou 1989

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G E O T E C H N I C A L D E S I G N OF THE M C L E L L A N MINE L Y N N L A K E , M A N I T O B A B y J O E Y L O U R O T Z I E N M . A . S c . , 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 , 1989 A T H E S I S S U B M I T T E D IN P A R T I A L F U L F I L L M E N T OF T H E R E Q U I R E M E N T S F O R THE D E G R E E OF M A S T E R OF A P P L I E D S C I E N C E in T H E F A C U L T Y OF G R A D U A T E S T U D I E S Depa r tmen t of M i n i n g and M ine ra l P r o c e s s E n g i n e e r i n g We accept th i s thes i s as con fo rm ing to the r e q u i r e d s t a n d a r d T H E 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 S e p t e m b e r , 1989 <D J O E Y L O U R O T Z I E N , 1989 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of M i n i n g and M i n e r a l P r o c e s s E n g i n e e r i n g The University of British Columbia Vancouver, Canada Date A p r i l 18, 1990  DE-6 (2/88) Abstract The overall objective of any geotechnical mine design procedure rrjust ! be to maximize the extraction of the ore reserves while maintaining the integrity of the working areas. At the McLellan Mine the cut-and-fill mining method was first adopted. This decision was made for flexibility in the size and shape of the mine openings to allow for the variability in width and grade of the ore zone. As a result the geotechnical design of the cut-and-fill stopes necessitated investigations to evaluate the character of the rock mass with regard to the hydrogeology, lithology, structural geology, rock strength and rock mass ratings at the site and to assess the in-situ stress conditions. In addition, the character of the backfill material had to be estimated prior to detailed testing. Based upon these parameters two dimensional finite element analyses were completed, the sill pillar and the two stopes were designed. Finally, remedial rock reinforcement was recommended for suspected unstable spans. i i T A B L E O F C O N T E N T S P A G E C H A P T E R 1 I N T R O D U C T I O N 1 1.1 S C O P E O F T H E W O R K 2 1.2 P H Y S I O G R A P H Y 4 1 . 2 . 1 L o c a t i o n 4 1 . 2 . 2 T o p o g r a p h y 4 1 . 2 . 3 C l i m a t e 6 1 .3 O R E B O D Y D E S C R I P T I O N 6 1.4 M I N I N G M E T H O D A N D S E Q U E N C E 8 1 .5 D E S I G N M E T H O D O L O G Y 9 1 .6 P R E S E N T A T I O N O F T H E W O R K 10 C H A P T E R 2 G E O L O G Y 13 2 .1 R E G I O N A L G E O L O G Y 14 2 . 2 S I T E G E O L O G Y 14 2 . 3 S T R U C T U R A L G E O L O G Y 16 2 . 4 C O N C L U S I O N S 19 C H A P T E R 3 H Y D R O G E O L O G Y 22 3 . 1 I N T R O D U C T I O N 23 3 . 1 . 1 S c o p e o f t h e W o r k 23 3 . 1 . 2 C u r r e n t F i e l d W o r k 23 3 . 2 R E S U L T S 24 3 . 2 . 1 S u r f a c e M a p p i n g P r o g r a m 24 3 . 2 . 2 U n d e r g r o u n d M a p p i n g P r o g r a m 27 3 . 2 . 3 R e v i e w o f C o r e L o g s 29 3 . 3 G E O H Y D R O L O G I C A L E N V I R O N M E N T 31 3 . 3 . 1 S u r f i c i a l H y d r o g e o l o g y 31 3 . 3 . 2 B e d r o c k H y d r o g e o l o g y 32 3 . 3 . 2 . 1 L i t h o l o g y 32 3 . 3 . 2 . 2 S t r u c t u r a l G e o l o g y 32 3 . 3 . 2 . 3 G e n e r a l H y d r o g e o l o g i c P r o p e r t i e s 34 3 . 4 C O N C L U S I O N S 35 C H A P T E R 4 R O C K M A S S C H A R A C T E R I Z A T I O N 38 4 . 0 I N T R O D U C T I O N 39 4 . 1 R O C K M A S S C L A S S I F I C A T I O N S Y S T E M S 40 4 . 2 R O C K M A S S C L A S S I F I C A T I O N 42 4 . 2 . 1 G e n e r a l 42 4 . 2 . 2 P r e v i o u s W o r k 42 4 . 2 . 3 P h a s e II P r o c e d u r e s 44 4 . 2 . 4 A s s e s s m e n t o f R a t i n g P a r a m e t e r s 45 4 . 2 . 5 R e s u l t s 49 i i i T A B L E O F C O N T E N T S P A G E C H A P T E R 4 R O C K M A S S C H A R A C T E R I Z A T I O N ( C o n t ' d ) 4 . 2 . 6 D i s c u s s i o n 51 4 . 2 . 6 . 1 H a n g i n g w a l l R o c k s 51 4 . 2 . 6 . 2 F o o t w a l l R o c k s 53 4 . 2 . 6 . 3 N o r t h S h e a r 56 4 . 2 . 6 . 4 E s t i m a t e d I n - S i t u S t r e n g t h 58 C h a r a c t e r i s t i c s 4 . 2 . 6 . 5 E s t i m a t e d S t a n d - u p T i m e s 63 4 . 3 D E T A I L E D I N V E S T I G A T I O N O F T H E N O R T H S H E A R 66 4 . 3 . 1 P r o c e d u r e 66 4 . 3 . 2 R e s u l t s 67 4 . 3 . 3 D i s c u s s i o n 68 4 . 4 U N I A X I A L C O M P R E S S I V E T E S T S 69 4 . 4 . 1 P r e v i o u s W o r k 69 4 . 4 . 2 S a m p l e P r e p a r a t i o n 70 4 . 4 . 3 T e s t P r o c e d u r e s 71 4 . 4 . 4 R e s u l t s 72 4 . 4 . 5 D i s c u s s i o n 73 4 . 5 T R I A X I A L T E S T S 75 4 . 5 . 1 G e n e r a l 75 4 . 5 . 2 T e s t P r o c e d u r e s 75 4 . 5 . 3 R e s u l t s 76 4 . 5 . 4 D i s c u s s i o n 77 4 . 6 S P E C I F I C G R A V I T Y T E S T S 79 4 . 6 . 1 P r e v i o u s W o r k 79 4 . 6 . 2 S a m p l e P r e p a r a t i o n 80 4 . 6 . 3 T e s t P r o c e d u r e s 80 4 . 6 . 4 R e s u l t s 81 4 . 6 . 5 D i s c u s s i o n 83 4 . 7 C O N C L U S I O N S 84 C H A P T E R 5 E S T I M A T I O N O F I N - S I T U S T R E S S E S 87 5 . 0 I N T R O D U C T I O N 88 5 .1 S T R E S S M E A S U R E M E N T E Q U I P M E N T 89 5 . 1 . 1 C S I R O H o l l o w I n c l u s i o n C e l l S y s t e m 89 5 . 1 . 2 D a t a R e c o r d i n g S y s t e m 91 5 . 1 . 3 B i a x i a l T e s t E q u i p m e n t 92 5 . 2 M E T H O D O L O G Y 93 5 . 3 T H E I N - S I T U S T R E S S M E A S U R E M E N T S 97 5 . 4 D A T A A N A L Y S I S 101 5 . 4 . 1 A n a l y s i s of S t r a i n R e l i e f C u r v e s 101 5 . 4 . 2 A n a l y s i s of B i a x i a l T e s t R e s u l t s 103 5 . 4 . 3 E x a m i n a t i o n of S e c t i o n e d O v e r c o r e 104 5 . 4 . 4 G e n e r a l 105 i v T A B L E O F C O N T E N T S P A G E C H A P T E R 5 E S T I M A T I O N O F I N - S I T U S T R E S S E S ( C o n t ' d ) 5 . 5 R E S U L T S 106 5 . 6 D I S C U S S I O N 106 5 . 6 . 1 S t r e s s M a g n i t u d e s 106 5 . 6 . 2 S t r e s s O r i e n t a t i o n s 113 5 .7 C O N C L U S I O N S 119 C H A P T E R 6 L I T E R A T U R E R E V I E W A N D E S T I M A T I O N 121 O F E N G I N E E R I N G P R O P E R T I E S O F B A C K F I L L 6 . 0 I N T R O D U C T I O N 122 6 .1 M A T E R I A L P R O P E R T I E S R E Q U I R E D 122 6 . 2 P E R C O L A T I O N R A T E 126 6 . 2 . 1 G e n e r a l 126 6 . 2 . 2 I n f l u e n c e of I n h e r e n t F i l l P r o p e r t i e s 131 6 . 2 . 2 . 1 G r a i n S h a p e 131 6 . 2 . 2 . 2 G r a i n S i z e D i s t r i b u t i o n 131 6 . 2 . 2 . 3 P o r o s i t y 132 6 . 2 . 3 H i s t o r i c a l V a l u e s o f P e r c o l a t i o n R a t e s 134 6 . 2 . 4 D i s c u s s i o n 137 6 . 3 B E A R I N G C A P A C I T Y 138 6 . 3 . 1 G e n e r a l 138 6 . 3 . 2 E s t i m a t e s o f I n p u t P a r a m e t e r s 139 6 . 3 . 2 . 1 B e a r i n g P r e s s u r e a n d C o n t a c t 139 A r e a 6 . 3 . 2 . 2 U n i t W e i g h t ( D e n s i t y ) a n d 139 I n t e r n a l A n g l e o f F r i c t i o n 6 . 3 . 2 . 3 C a p i l l a r i t y 140 6 . 3 . 3 E s t i m a t e s of B e a r i n g C a p a c i t y 143 6 . 3 . 3 . 1 I n f l u e n c e o f C a p i l l a r i t y 143 6 . 3 . 3 . 2 I n f l u e n c e of S o i l W e i g h t 146 a n d F o u n d a t i o n W i d t h 6 . 3 . 4 D y n a m i c A n a l y s i s o f I m p a c t o f B l a s t e d 148 M u c k o n S u r f a c e o f B a c k f i l l 6 . 3 . 4 . 1 A s s u m p t i o n s 148 6 . 3 . 4 . 2 D y n a m i c A n a l y s i s 149 6 . 3 . 5 D i s c u s s i o n 153 6 . 3 . 5 . 1 S u p p o r t W o r k e r s W i t h i n 12 H o u r s 153 6 . 3 . 5 . 2 S u p p o r t M u c k a f t e r 2 d a y s 154 6 . 3 . 5 . 3 S u p p o r t E q u i p m e n t W i t h i n 2 . 5 155 D a y s w i t h 0 . 6 m C o v e r of M u c k 6 . 3 . 5 . 4 S u p p o r t E q u i p m e n t W i t h i n 156 T w o W e e k s V T A B L E OF C O N T E N T S P A G E 6 . 4 S U P P O R T C A P A B I L I T Y OF F I L L 158 6 . 4 . 1 G e n e r a l 158 6 . 4 . 2 H i s t o r i c a l D a t a 159 6 . 4 . 3 D i s c u s s i o n 159 6 . 5 C O N C L U S I O N S 162 C H A P T E R 7 N U M E R I C A L M O D E L L I N G 165 7 . 1 I N T R O D U C T I O N 166 7 . 2 N U M E R I C A L M O D E L L I N G 167 7 . 2 . 1 S e l e c t i n g a n u m e r i c a l m o d e l 167 7 . 2 . 2 D e s i g n of t h e G e o m e t r i c a l M o d e l 170 7 . 2 . 2 . 1 C h o i c e of G e o l o g i c a l S e c t i o n s 170 7 . 2 . 2 . 2 D e t a i l e d G e o m e t r y of S e c t i o n 0+00 171 7 . 2 . 3 S i m u l a t i o n of E x c a v a t i o n S e q u e n c e 173 7 . 2 . 4 M o d e l l i n g R e m e d i a l M e a s u r e s 174 7 . 3 D E S I G N P A R A M E T E R S 176 7 . 3 . 1 R o c k M a s s P a r a m e t e r s 178 7 . 3 . 1 . 1 Y o u n g ' s M o d u l u s 178 7 . 3 . 1 . 2 P o i s s o n ' s R a t i o 178 7 . 3 . 1 . 3 D e n s i t y 179 7 . 3 . 2 H y d r a u l i c B a c k f i l l P a r a m e t e r s 179 7 . 3 . 3 S t i f f B a c k f i l l P a r a m e t e r s 179 7 . 3 . 4 I n - S i t u S t r e s s 180 7 . 4 N U M E R I C A L M O D E L L I N G I N V E S T I G A T I O N S 181 7 . 5 R E S U L T S 183 7 . 6 D I S C U S S I O N 183 7 . 7 C O N C L U S I O N S 185 C H A P T E R 8 D E S I G N A N A L Y S E S 186 8 .1 I N T R O D U C T I O N 187 8 . 2 S T O P E D E S I G N 189 8 . 2 . 1 S t o p e Wal l S t a b i l i t y 189 8 . 2 . 1 . 1 N G I A n a l y s i s 191 8 . 2 . 1 . 2 T h e G o l d e r M e t h o d 192 8 . 2 . 1 . 3 D i s c u s s i o n o n S t a b i l i t y o f S t o p e Wa l l s 198 8 . 2 . 2 S t o p e R o o f S t a b i l i t y 198 8 . 2 . 2 . 1 S t r u c t u r a l S t a b i l i t y 198 8 . 2 . 2 . 2 N G I A n a l y s i s 199 8 . 2 . 2 . 3 T h e G o l d e r M e t h o d 200 8 . 2 . 2 . 4 D i s c u s s i o n o n S t a b i l i t y o f T e m p o r a r y S t o p e R o o f 202 vi T A B L E O F C O N T E N T S P A G E C H A P T E R 8 D E S I G N A N A L Y S E S ( C o n t ' d ) 8 . 3 S I L L P I L L A R D E S I G N 203 8 . 3 . 1 S t r u c t u r a l A n a l y s i s 203 8 . 3 . 2 S t r e s s A n a l y s i s 203 8 . 3 . 2 . 1 N u m e r i c a l A n a l y s i s 205 8 . 3 . 2 . 2 H o e k ' s F a i l u r e C r i t e r i o n 207 8 . 3 . 2 . 3 P i l l a r S t r e n g t h A n a l y s i s 208 8 . 3 . 3 D i s c u s s i o n of R e s u l t s 209 8 . 4 C O N C L U S I O N S 212 C H A P T E R 9 S U M M A R Y A N D C O N C L U S I O N S 215 9 . 1 M I N I N G E N V I R O N M E N T 216 9 . 2 G E O L O G Y 216 9 . 3 H Y D R O G E O L O G Y 217 9 . 4 R O C K M A S S C H A R A C T E R I Z A T I O N 217 9 . 5 I N - S I T U S T R E S S C O N D I T I O N S 219 9 . 6 E N G I N E E R I N G P R O P E R T I E S O F B A C K F I L L 220 9 . 7 N U M E R I C A L M O D E L L I N G 222 9 . 8 M I N E D E S I G N 223 B I B L I O G R A P H Y 226 Vii L I S T O F T A B L E S P A G E 4 . 1 V a r i a t i o n i n R o c k M a s s Q u a l i t y : P h a s e I 43 4 . 2 S t r e n g t h P a r a m e t e r C o n v e r s i o n T a b l e 47 4 . 3 S u m m a r y of R o c k M a s s R a t i n g f o r E a c h D o m a i n 50 4 . 4 A p p r o x i m a t e R e l a t i o n s h i p b e t w e e n R o c k M a s s 59 Q u a l i t y a n d M a t e r i a l C o n s t a n t s 4 . 5 E s t i m a t e d S t a n d - u p T i m e f o r U n s u p p o r t e d S p a n s 64 4 . 6 R e s u l t s o f P h a s e I. T e s t s 69 4 . 7 U n i a x i a l C o m p r e s s i v e T e s t R e s u l t s 72 4 . 8 A n i s o t r o p i c V a r i a t i o n i n R o c k C h a r a c t e r i s t i c s 73 4 . 9 S u m m a r y o f D e s i g n V a l u e s 74 4 . 1 0 S u m m a r y o f T r i a x i a l T e s t R e s u l t s 76 4 . 1 1 S p e c i f i c G r a v i t y of O r e Z o n e M a t e r i a l 79 4 . 1 2 S p e c i f i c G r a v i t y o f H o s t R o c k s 82 4 . 1 3 D e s i g n V a l u e s f o r N u m e r i c a l M o d e l l i n g 86 5 . 1 E v a l u a t i o n of C a l c u l a t e d S t r e s s e s 108 6 . 1 S u m m a r y o f H i s t o r i c a l P e r c o l a t i o n R u l e s 135 6 . 2 T y p i c a l V o i d R a t i o s a n d W e i g h t s o f S i n g l e 141 G r a i n e d S t r u c t u r e s 6 . 3 A n g l e o f I n t e r n a l F r i c t i o n o f C o h e s i o n l e s s 141 S o i l s C o m p o s e d L a r g e l y o f Q u a r t z 6 . 4 E s t i m a t e d C a p i l l a r y T e n s i o n 143 6 . 5 E s t i m a t e d B e a r i n g C a p a c i t y D u e to N e g a t i v e 145 P o r e P r e s s u r e 6 . 6 E s t i m a t e d B e a r i n g C a p a c i t y D u e to S o i l 147 W e i g h t f o r S c o o p t r a m s 6 . 7 E s t i m a t e d P e n e t r a t i o n of M u c k i n t o B a c k f i l l 153 6 . 8 E s t i m a t e d B e a r i n g C a p a c i t y o f F i l l F o r O r e 155 6 . 9 S u m m a r y o f H i s t o r i c a l R a n g e o f M a t e r i a l 161 P r o p e r t i e s 6 . 1 0 R a n g e o f D e s i g n P a r a m e t e r s 164 7 . 1 S u m m a r y o f D e s i g n P a r a m e t e r s 177 7 . 2 R a n g e o f M a t e r i a l P r o p e r t i e s U s e d i n 182 S e n s i t i v i t y A n a l y s e s 7 . 3 C o m p a r i s o n o f C l o s u r e o f L o w e r S t o p e a n d 184 A v e r a g e P r i n c i p a l S t r e s s e s i n S i l l P i l l a r 7 . 4 S u m m a r y o f S t r e s s e s I n d u c e d i n L o w e r S t o p e 1 8 4 B 8 . 1 R e s u l t s o f G o l d e r A n a l y s i s o n S t o p e Wa l l s 197 8 . 2 S u m m a r y o f C r i t i c a l R o c k M a s s R a t i n g f o r 199 a S t a b l e R o o f o f a G i v e n S p a n 8 . 3 R e s u l t s of G o l d e r A n a l y s i s o n S t o p e R o o f 201 8 . 4 S u m a r y of C o n d i t i o n s M o d e l l e d 207 9 . 1 D e s i g n V a l u e s f o r N u m e r i c a l M o d e l l i n g 219 9 . 2 R a n g e o f D e s i g n P a r a m e t e r s 222 v i i i L I S T O F F I G U R E S P A G E 1.1 L o c a t i o n M a p 5 1.2 S i t e Map 7 2 .1 R e g i o n a l G e o l o g y 15 2 . 2 S i t e G e o l o g y 17 2 . 3 G e o l o g i c a l C r o s s - s e c t i o n a t 0+00 E 18 2 . 4 S t e r e o n e t P l o t o f S t r u c t u r a l D i s c o n t i n u i t i e s 20 3 .1 E s t i m a t e d T o p o f F r e s h B e d r o c k S u r f a c e 26 4 . 1 R o c k M a s s R a t i n g v s . E l e v a t i o n : 52 H a n g i n g w a l l R o c k s 4 . 2 R o c k M a s s R a t i n g v s . D e p a r t u r e : 53 H a n g i n g w a l l R o c k s 4 . 3 R o c k M a s s R a t i n g of T u f f a c e o u s S e d i m e n t s 55 i n F o o t w a l l 4 . 4 R o c k M a s s R a t i n g s of C h l o r i t i z e d A n d e s i t e 55 i n F o o t w a l l 4 . 5 R o c k M a s s R a t i n g v s . E l e v a t i o n - 57 N o r t h S h e a r 4 . 6 R o c k M a s s R a t i n g v s . D e p a r t u r e - N o r t h S h e a r 57 4 . 7 R e l a t i o n s h i p B e t w e e n I n - S i t u D e f o r m a t i o n 62 M o d u l e s o f R o c k M a s s e s a n d R o c k M a s s C l a s s i f i c a t i o n 4 . 8 R e l a t i o n s h i p B e t w e e n t h e S t a n d - u p T i m e o f a n 63 U n s u p p o r t e d S p a n a n d R o c k M a s s R a t i n g 4 . 9 M o h r ' s C i r c l e s f r o m T r i a x i c a l T e s t D a t a 78 5 .1 H o l l o w I n c l u s i o n C e l l a n d I n s t a l l a t i o n C o m p o n e n t s 90 5 . 2 P r o c e d u r e f o r I n s t a l l a t i o n a n d O v e r c o r i n g o f 94 H o l l o w I n c l u s i o n S t r a i n C e l l 5 . 3 L o c a t i o n o f 370m L e v e l S i t e 98 5 . 4 L o c a t i o n o f 240m L e v e l S i t e 99 5 . 5 D i a g n o s t i c C u r v e s f o r I n t e r p r e t a t i o n of 102 O v e r c o r i n g T e s t R e s u l t s 5 . 6 V a r i a t i o n i n V e r t i c a l S t r e s s w i t h D e p t h f r o m 109 V a l u e s O b t a i n e d W o r l d w i d e 5 . 7 V a r i a t i o n i n H o r i z o n t a l S t r e s s to V e r t i c a l 110 S t r e s s R a t i o f r o m V a l u e s O b t a i n e d W o r l d w i d e 5 . 8 V a r i a t i o n i n H o r i z o n t a l S t r e s s to V e r t i c a l 111 S t r e s s R a t i o f r o m V a l u e s O b t a i n e d f r o m N o r t h e r n M a n i t o b a 5 . 9 V a r i a t i o n i n H o r i z o n t a l S t r e s s w i t h D e p t h i n 112 N o r t h e r n M a n i t o b a 5 . 1 0 O r i e n t a t i o n of P r i n c i p a l S t r e s s e s o n b o t h l e v e l s 114 5 .11 C o m p a r i s o n of A v e r a g e O r i e n t a t i o n o f P r i n c i p a l 115 S t r e s s e s w i t h A v e r a g e O r i e n t a t i o n a t R u t t a n M i n e 5 . 1 2 C o m p a r i s o n o f A v e r a g e O r i e n t a t i o n s of P r i n c i p a l 116 S t r e s s e s w i t h S t r u c t u r a l G e o l o g y i x L I S T O F F I G U R E S - P A G E 5 . 1 3 C o m p a r i s o n of O r i e n t a t i o n o f M a j o r P r i n c i p a l 118 S t r e s s w i t h R e g i o n a l G e o l o g y 6 .1 H i s t o r i c a l G r a i n S i z e D i s t r i b u t i o n C u r v e s 133 f o r B a c k f i l l 6 . 2 R e c o m m e n d e d R a n g e of G r a i n S i z e D i s t r i b u t i o n 136 f o r B a c k f i l l M a t e r i a l 6 . 3 S t r e s s D i s t r i b u t i o n U n d e r a F o o t i n g 151 7 . 1 D e s i g n of G e o m e t r i c a l M o d e l f o r A n a l y s i s 172 b y F i n i t e E l e m e n t M e t h o d 7 . 2 S e q u e n c e of S i m u l a t i o n of M i n i n g 175 8 .1 G r a p h i c a l C o m p a r i s o n of O r i e n t a t i o n o f 190 S t o p e s w i t h t h e G e o l o g i c a l D i s c o n t i n u i t i e s 8 . 2 G r a p h of S t a b i l i t y N u m b e r ( N ) V e r s u s S h a p e 193 F a c t o r ( s ) 8 . 3 G r a p h to D e t e r m i n e t h e R o c k S t r e s s F a c t o r ( A ) 194 8 . 4 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 ( B ) 195 8 . 5 S t r u c t u r a l A n a l y s i s of S i l l P i l l a r 204 8 . 6 S t r e s s : S t r e n g t h R a t i o v s . P i l l a r W i d t h 211 f o r t h e S i l l P i l l a r a t t h e M c L e l l a n S i t e X A P P E N D I C E S I. S U R F A C E D R I L L H O L E W A T E R L E V E L S I I . S U M M A R Y O F U N D E R G R O U N D H Y D R O G E O L O G I C M A P P I N G I I I . R A N G E O F V A L U E S O F H Y D R A U L I C C O N D U C T I V I T Y A N D P E R M E A B I L I T Y I V . C S I R 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 F O R J O I N T E D R O C K V . C O M P U T E R C O D E S F O R D I A M O N D D R I L L C O R E L O G S V I . S A M P L E D I A M O N D D R I L L C O R E L O G F O R P A R T O F H O L E A U 84-46 V I I . P A R T I A L S U M M A R I Z E D 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 F O R H O L E A U 84-46 V I I I . P A R T I A L C O M P U T E R P R I N T O U T F O R T U F F A C E O U S S E D I M E N T S I N F O O T W A L L I X . S U M M A R Y O F D E T A I L E D I N V E S T I G A T I O N O F T H E N O R T H S H E A R X . S T R E S S - S T R A I N C U R V E S F O R U N I A X I A L C O M P R E S S I V E T E S T S O B T A I N E D F R O M L V D T R E A D I N G S X I . S T R E S S - S T R A I N C U R V E S F O R U N I A X I A L T E S T S F R O M S T R A I N C A U G E S X I I . S T R E S S - S T R A I N C U R V E S F O R T R I A X I A L T E S T S X I I I . S P E C I F I C G R A V I T Y T E S T D A T A X I V . S T R A I N R E L I E F C U R V E S F R O M O V E R C O R I N G X V . A D J U S T E D S T R A I N R E L I E F C U R V E S F O R O V E R C O R E N O . 2 A N D 3 X V I . S T R E S S - S T R A I N C U R V E S F R O M B I A X I A L T E S T S X V I I . M A J O R P R I N C I P A L S T R E S S D I S T R I B U T I O N A R O U N D T H E M I N E O P E N I N G S F O R S T A G E 6 T H R O U G H 1 2 E X C A V A T I O N S W I T H N O A D D I T I O N A L S U P P O R T X V I I I M A J O R P R I N C I P A L S T R E S S D I S T R I B U T I O N A R O U N D T H E M I N E O P E N I N G S F O R S T A G E 12 E X C A V A T I O N S W I T H V A R I O U S R E M E D I A L M E A S U R E S X I X . C O N T O U R E D S T R E S S D I S T R I B U T I O N I N T H E S I L L P I L L A R F O R S T A G E 1 2 E X C A V A T I O N X X . D E T A I L E D S T R E S S C O N D I T I O N S I N T H E S I L L P I L L A R F O R E A C H C O M P U T E R R U N X X I . S I L L P I L L A R S T A B I L I T Y A N A L Y S I S x i A C K N O W L E D G E M E N T S T h e a u t h o r w o u l d l i k e to t h a n k S h e r r i t t G o r d o n M i n e s L t d . f o r t h e i r s u p p o r t a n d a s s i s t a n c e d u r i n g t h e p r e p a r a t i o n of t h i s t h e s i s . In a d d i t i o n h e w o u l d l i k e to s t a t e h i s a p p r e c i a t i o n f o r t h e s u p p o r t a n d g u i d a n c e of D r . H . D . S . M i l l e r , t h e i n v a l u a b l e h e l p o f M r . M . A . S t o a k e s a n d D o l m a g e C a m p b e l l a n d A s s o c i a t e s (1975) L t d . w h o p r o v i d e d s u p p o r t a n d t h e w i l l i n g s e r v i c e s of M r s . D . M a n a r o v i c i w h o t y p e d t h e m a n u s c r i p t . To my w i f e a n d c h i l d r e n I e x p r e s s my g r a t i t u d e f o r t h e i r c o n t i n u a l s u p p o r t a n d u n d e r s t a n d i n g . x i i 1 C H A P T E R 1 I N T R O D U C T I O N 2 1.1 S C O P E O F T H E W O R K T h e r e s e a r c h w o r k p r e s e n t e d i n t h i s t h e s i s h a s b e e n c o m p l e t e d u n d e r a r e s e a r c h g r a n t f u n d e d b y S h e r r i t t G o r d o n M i n e s L t d . to p r o v i d e a r o c k m e c h a n i c s p r o g r a m , an i n v e s t i g a t i o n i n t o t h e g e o m e c h a n i c a l c h a r a c t e r i s t i c s of t h e r o c k s a t t h e M c L e l l a n M i n e a n d a d e s i g n o f t h e p r i m a r y u n d e r g r o u n d o p e n i n g s . T h e w o r k c o m m e n c e d i n t h e f a l l o f 1983 w i t h a n i n i t i a l u n d e r g r o u n d m a p p i n g p r o g r a m , t h e i n s t i t u t i o n o f a n o n g o i n g g e o m e c h a n i c a l c o r e l o g g i n g p r o g r a m a n d a l a b o r a t o r y t e s t i n g p r o g r a m . In t h e f a l l o f 1984 t h e r e s e a r c h g r a n t w a s e x t e n d e d to p r o v i d e d a t a f o r a f i n a l g e o m e c h a n i c a l m i n e d e s i g n . T h e o b j e c t i v e s a t t h a t t ime c o n s i s t e d o f : 1) D e t e r m i n a t i o n of f i e l d s t r e s s c o n d i t i o n s a t t h e A g a s s i z M i n e . ( T h e name of t h e m i n e w a s c h a n g e d i n 1985 f r o m A g a s s i z M i n e to M c L e l l a n M i n e ) . 3 2) C o n t i n u a t i o n of i n v e s t i g a t i o n s i n t o t h e s p a t i a l v a r i a b i l i t y o f t h e r o c k m a s s q u a l i t y a n d i n t a c t r o c k s t r e n g t h a n d , 3 ) A n a l y s i s of t h e c o l l e c t e d d a t a b y n u m e r i c a l m e t h o d s to i n v e s t i g a t e : a) T h e o p t i m u m d e s i g n of s t o p e s a n d p i l l a r s b ) T h e o p t i m u m m i n i n g s e q u e n c e c ) T h e e f f e c t o f t h e N o r t h S h e a r d ) T h e s u r f a c e a n d s u b - s u r f a c e s u b s i d e n c e d u e to m i n i n g a n d i t s e f f e c t s o n m i n e p l a n n i n g a s r e l a t e d to m i n i n g b y e i t h e r t h e o p e n s t o p i n g o r s h r i n k a g e s t o p i n g m e t h o d s . H o w e v e r , f u r t h e r e x p l o r a t i o n w o r k d u r i n g 1984 a n d e a r l y 1985 s h o w e d t h a t t h e o r e b o d y i s h i g h l y i r r e g u l a r a n d no t a m e n a b l e to m i n i n g b y t h e s e m e t h o d s . In t h e s p r i n g o f 1985 S h e r r i t t G o r d o n M i n e s L t d . m a d e a d e c i s i o n to p r o c e e d w i t h m i n e p l a n n i n g o n t h e b a s i s of u s i n g t h e c u t - a n d - f i l l m i n i n g m e t h o d . T h u s t h e f i n a l o b j e c t i v e s o f t h e r e s e a r c h w o r k w e r e m o d i f i e d to p r o v i d e d a t a as i n o b j e c t i v e s 1 a n d 2 a b o v e , to e s t i m a t e t h e b e n e f i t s o f m i n i n g w i t h b a c k f i l l a n d to e s t i m a t e t h e m i n i m u m s a f e p i l l a r w i d t h b e t w e e n two c u t - a n d - f i l l s t o p e s w i t h b o t t o m e l e v a t i o n s of 1160 m e t r e s a n d 1300 m e t r e s . In a d d i t i o n , t h e w o r k w a s to i n c l u d e t h e d e s i g n o f a n y r o c k r e i n f o r c e m e n t 4 r e q u i r e d i n t h e s t o p e s a n d to a s s e s s t h e d i l u t i o n o f o r e g r a d e m a t e r i a l b y w a s t e r o c k f r o m t h e w a l l s o f t h e s t o p e s a n d f r o m p e n e t r a t i o n of o r e g r a d e m a t e r i a l i n t o t h e b a c k f i l l . In l a te 1985 t h e w o r k w a s a g a i n e x t e n d e d to c o v e r t h e a s s e s s m e n t o f l o c a l g l a c i o - f l u v i a l s a n d a n d g r a v e l a s b a c k f i l l m a t e r i a l . 1 .2 P H Y S I O G R A P H Y 1 . 2 . 1 L o c a t i o n T h e M c L e l l a n M i n e i s l o c a t e d n o r t h of t h e f i f t y - e i g h t h p a r a l l e l i n M a n i t o b a a p p r o x i m a t e l y 67 k i l o m e t e r s n o r t h e a s t o f t h e t o w n o f L y n n L a k e , 225 k i l o m e t e r s n o r t h b y n o r t h w e s t f r o m W i n n i p e g . A c c e s s to t h e m i n e s i t e i s b y m e a n s of 5 k i l o m e t e r s o f a l l - w e a t h e r d i r t r o a d a n d t h r e e k i l o m e t e r s o f p a v e d r o a d f r o m L y n n L a k e . 1 . 2 . 2 T o p o g r a p h y T h e t o p o g r a p h y of t h e r e g i o n c o n s i s t s o f r o l l i n g h i l l s a n d s w a m p s w i t h a r e l a t i v e l y t h i n v e n e e r of g l a c i a l t i l l a n d g l a c i a l o u t w a s h d e p o s i t s o v e r l y i n g b e d r o c k o f t h e P r e c a m b r i a n S h i e l d . B e d r o c k o u t c r o p s a r e r e l a t i v e l y s p a r s e i n t h e a r e a o f t h e m i n e . F i g u r e 1.1 - L o c a t i o n M a p 6 T h e s u r f a c e e l e v a t i o n of t h e s i t e r a n g e s f r o m a p p r o x i m a t e l y 1500 m e t r e s a t t h e K e e w a t i n r i v e r to a p p r o x i m a t e l y 1550 m e t r e s t o t h e n o r t h e a s t o f t h e m i n e s h a f t ( F i g u r e 1 . 2 ) . 1 . 2 . 3 C l i m a t e T h e c l i m a t e i n t h e a r e a o f t h e m i n e s i t e i s s e v e r e w i t h m a x i m u m d a i l y t e m p e r a t u r e s r a n g i n g f r o m 3 5 ° C i n t h e s u m m e r to - 4 0 ° C i n t h e w i n t e r m o n t h s . H i s t o r i c a l r e c o r d s r e v e a l t h a t t h e a r e a i s s u b j e c t to a p p r o x i m a t e l y 60 f r o s t - f r e e d a y s p e r y e a r . A s s u c h , a r e a s o f p e r m a f r o s t e x i s t i n a n d a r o u n d t h e m i n e s i t e . 1 .3 O R E B O D Y D E S C R I P T I O N T h e o r e b o d y a t t h e M c L e l l a n M i n e i s a n e a r v e r t i c a l , i r r e g u l a r s h a p e d z o n e of g o l d - s i l v e r m i n e r a l i z a t i o n . T h e e c o n o m i c z o n e i s b o u n d e d o n t h e H a n g i n g w a l l b y a 0 . 3 to 6 . 0 m e t r e t h i c k s h e a r z o n e c a l l e d t h e N o r t h S h e a r . T h e o r e z o n e r a n g e s f r o m 2 to 25 m e t r e s t h i c k a l o n g a s t r i k e l e n g t h o f a p p r o x i m a t e l y 400 m a n d e x t e n d s f r o m s u r f a c e to a m i n i m u m d e p t h of 480 m e t r e s . T h e m i n e a b l e o r e r e s e r v e s a t t h e M c L e l l a n M i n e , a s d e f i n e d b y t h e l i m i t i n g p a r a m e t e r s o f a c u t - o f f g r a d e o f 0 . 1 3 o z / t o n F i g u r e 1.2 - S i t e Map 8 o v e r a m i n i m u m o f a 3 m e t r e m i n i n g w i d t h , h a v e b e e n e s t i m a t e d a t 1 .52 m i l l i o n t o n s p r o b a b l e , p o s s i b l e a n d i n f e r r e d r e s e r v e s a v e r a g i n g 0 . 1 9 o z . / t o n . 1.4 M I N I N G M E T H O D A N D S E Q U E N C E B e c a u s e o f t h e i r r e g u l a r n a t u r e of t h e o r e b o d y a n d t h e e x i s t e n c e of a s h e a r z o n e i n t h e h a n g i n g w a l l , c u r r e n t p l a n s c a l l f o r m i n i n g b y c u t - a n d - f i l l m e t h o d s u s i n g h y d r a u l i c b a c k f i l l . It i s p l a n n e d to c o m m e n c e m i n i n g i n a n u p p e r s t o p e f r o m 1280 m e t r e s e l e v a t i o n (240 m L e v e l ) w i t h a l o w e r s t o p e to b e d e v e l o p e d f r o m t h e 370 m L e v e l (1150 m e l e v a t i o n ) . L a t e r d e v e l o p m e n t w i l l a c c e s s o r e a b o v e 1400 m e l e v a t i o n a n d p o s s i b l y b e l o w 1150 m e t r e e l e v a t i o n . T h e m i n i n g of t h e l o w e r s t o p e i s e x p e c t e d to l a g a p p r o x i m a t e l y 3 m o n t h s b e h i n d t h e m i n i n g o f t h e u p p e r s t o p e . T h e s t o p e s w i l l b e a c c e s s e d v i a a s p i r a l r a m p l o c a t e d s o u t h e a s t of t h e s t o p e i n t h e f o o t w a l l r o c k s . F r o m t h i s r a m p a c c e s s d r i f t s w i l l b e d r i v e n to a p p r o x i m a t e l y t h e c e n t r e , l o n g i t u d i n a l l y , o f t h e o r e z o n e . F r o m t h i s l o c a t i o n e a c h c u t o f 4 . 2 6 m w i l l b e e x c a v a t e d to t h e e a s t e r n a n d w e s t e r n l i m i t s of t h e o r e b o d y . T h e c u t w i l l t h e n b e b a c k f i l l e d to w i t h i n 0 . 6 m 9 tjf t h e b a c k w i t h h y d r a u l i c f i l l . A n e w a c c e s s r a m p w i l l t h e n b e e x c a v a t e d f r o m t h e s p i r a l r a m p to t h e e l e v a t i o n o f t h e n e x t h i g h e r c u t . A s t h e n e x t c u t i s m i n e d , 0 . 6 m o f m u c k w i l l b e l e f t o n t h e f l o o r o f t h e c u t to i m p r o v e t h e b e a r i n g c a p a c i t y o f t h e f l o o r . W h e n t h e c u t i s c o m p l e t e d , t h e 0 . 6 m of m u c k i n t h e f l o o r w i l l b e c l e a n e d u p a n d t h e n e x t f i l l c y c l e w i l l c o m m e n c e . I t i s a n t i c i p a t e d t h a t e a c h c u t - a n d - f i l l c y c l e w i l l t a k e a p p r o x i m a t e l y 3 w e e k s to c o m p l e t e . 1 .5 D E S I G N M E T H O D O L O G Y T h e o v e r a l l o b j e c t i v e of a n y g e o t e c h n i c a l m i n e d e s i g n p r o c e d u r e m u s t b e to m a x i m i z e t h e e x t r a c t i o n of t h e o r e r e s e r v e s w h i l e m a i n t a i n i n g t h e i n t e g r i t y o f t h e w o r k i n g a r e a s i n t h e m i n e . In t h e n e a r s u r f a c e c u t - a n d - f i l l m i n i n g e n v i r o n m e n t a t t h e M c L e l l a n M i n e i t i s t h e r e f o r e n e c e s s a r y t o : 1) E v a l u a t e t h e g e o l o g i c a l e n v i r o n m e n t a t t h e m i n e s i t e w i t h r e s p e c t to m i n i n g c o n d i t i o n s , 2 ) E v a l u a t e t h e h y d r o g e o l o g i c a l e n v i r o n m e n t a n d i t s i m p l i c a t i o n s w i t h r e s p e c t to w a t e r i n f l o w s i n t o t h e m i n e w o r k i n g s a n d e f f e c t o f t h e w a t e r o n t h e s t r e n g t h o f t h e r o c k m a s s , 10 3) C h a r a c t e r i z e t h e e n g i n e e r i n g p r o p e r t i e s o f t h e r o c k m a s s a t t h e s i t e , 4 ) E s t i m a t e t h e v i r g i n s t r e s s c o n d i t i o n s a t t h e m i n e s i t e , 5) E s t i m a t e t h e i n - p l a c e e n g i n e e r i n g p r o p e r t i e s of t h e b a c k f i l l m a t e r i a l a n d i t s e f f e c t s on t h e s t a b i l i t y of t h e u n d e r g r o u n d o p e n i n g s , 6) U s i n g t h e d a t a o b t a i n e d f r o m I t ems 1 t h r o u g h 5 a n d a n u m e r i c a l m o d e l , e s t i m a t e t h e r e a c t i o n o f t h e b a c k f i l l m a t e r i a l , t h e s t o p e w a l l s a n d t h e s i l l p i l l a r to t h e m i n i n g m e t h o d a n d s e q u e n c e , 7 ) A n a l y z e t h e r e s u l t s of t h e n u m e r i c a l m o d e l l i n g b y some f a i l u r e a n d / o r d e s i g n c r i t e r i a a n d 8 ) A n a l y z e t h e r e q u i r e m e n t s a n d / o r e f f e c t s of r e m e d i a l m e a s u r e s to i m p r o v e t h e m i n i n g e n v i r o n m e n t . 1 .6 P R E S E N T A T I O N O F T H E W O R K T h e r e s e a r c h w o r k d i s c u s s e d i n t h i s t h e s i s i s p r e s e n t e d i n t e r m s - o f i n f o r m a t i o n g a t h e r i n g , d a t a a n a l y s i s a n d c o n c l u s i o n s d r a w n . E a c h c h a p t e r d i s c u s s e s o n e a s p e c t o f t h e w o r k a n d p r e s e n t s c o n c l u s i o n s d r a w n f r o m t h a t w o r k . In a d d i t i o n , t h e f i n a l c o n c l u s i o n s a r e p r e s e n t e d i n a s e p a r a t e c h a p t e r . C h a p t e r T w o p r e s e n t s t h e r e g i o n a l a n d s i t e g e o l o g y a t a n d 11 s u r r o u n d i n g t h e M c L e l l a n M i n e , c o n c e n t r a t i n g p r i m a r i l y on f a c t o r s a f f e c t i n g t h e u n d e r g r o u n d m i n e d e s i g n . D u e to t h e c l o s e p r o x i m i t y of t h e K e e w a t i n R i v e r to t h e m i n e s i t e t h e t h i r d c h a p t e r i s d e v o t e d to t h e h y d r o g e o l o g i c a l c o n d i t i o n s a t t h e s i t e . In C h a p t e r F o u r t h e c h a r a c t e r i z a t i o n o f t h e r o c k m a s s i s p r e s e n t e d as o b t a i n e d f r o m g e o m e c h a n i c a l l o g g i n g o f d i a m o n d d r i l l c o r e a n d l a b o r a t o r y t e s t i n g . T h e i n - s i t u s t r e s s m e a s u r e m e n t p r o g r a m i s p r e s e n t e d i n C h a p t e r F i v e . C h a p t e r S i x c o n s i s t s of a l i t e r a t u r e r e v i e w of t h e e n g i n e e r i n g c h a r a c t e r i s t i c s o f h y d r a u l i c b a c k f i l l , t h e r e s u l t s of t e s t i n g , to d a t e , o f t h e p r e p a r e d h y d r a u l i c b a c k f i l l m a t e r i a l , a n d a n e s t i m a t i o n of t h e i n - s i t u c h a r a c t e r i s t i c s o f t h i s m a t e r i a l w h e n p l a c e d i n t h e s t o p e s . In C h a p t e r S e v e n t h e n u m e r i c a l m o d e l l i n g o f t h e s t o p e s i s p r e s e n t e d . D a t a p r e s e n t e d i n C h a p t e r s T w o to S i x a r e u s e d to m o d e l t h e c o n d i t i o n s a t t h e s i t e i n a f i n i t e e l e m e n t m o d e l . G e n e r a l c o n c l u s i o n s d e r i v e d f r o m t h e m o d e l a r e a l s o p r e s e n t e d . 12 T h e d e s i g n a n a l y s i s o f t h e r e s u l t s of t h e n u m e r i c a l m o d e l l i n g f o r t h e s t o p e s a n d s i l l p i l l a r a r e p r e s e n t e d i n C h a p t e r E i g h t . C h a p t e r N i n e c o n s i s t s of a s u m m a r y of c o n c l u s i o n s d e r i v e d f r o m t h i s r e s e a r c h w o r k . C H A P T E R 2 G E O L O G Y 14 2.1 R E G I O N A L G E O L O G Y T h e M c L e l l a n M i n e i s l o c a t e d i n a g e n t l y u n d u l a t i n g g l a c i a l o u t w a s h p l a i n ( F i g u r e 2.1) u n d e r l a i n b y P r o t e r o z o i c r o c k s o f t h e L y n n L a k e G r e e n s t o n e B e l t w h i c h c o m p r i s e p a r t o f t h e C h u r c h i l l S t r u c t u r a l P r o v i n c e . T w o e x t e n s i v e s u c c e s s i o n s o f t h e W a s e k w a n G r o u p o f t h e L y n n L a k e G r e e n s t o n e B e l t h a v e b e e n m a p p e d i n n o r t h e a s t e r l y t r e n d i n g b e l t s . T h e M c L e l l a n M i n e i s l o c a t e d w i t h i n t h e n o r t h e r n b e l t b e t w e e n M o t r i u k L a k e a n d E a g l e L a k e . T h i s n o r t h e r n b e l t c o n s i s t s p r i m a r i l y o f m a f i c v o l c a n i c r o c k s w i t h i n t e r c a l a t e d f e l s i c a n d i n t e r m e d i a t e u n i t s .3 T h e e m p l a c e m e n t o f s m a l l s u b v o l c a n i c p l u t o n s a n d l a r g e m a f i c a n d f e l s i c p l u t o n s d u r i n g a n d s u b s e q u e n t to t h e d e p o s i t i o n o f t h e W a s e k w a n G r o u p r e s u l t e d i n m e t a m o r p h i s m a n d f o l d i n g o f t h e s e q u e n c e . 2.2 S I T E G E O L O G Y A t a n d i m m e d i a t e l y s u r r o u n d i n g t h e M c L e l l a n M i n e s i t e t h e W a s e k w a n G r o u p c o n s i s t s o f s t e e p l y i n c l i n e d i n t e r m e d i a t e a n d I S I C K L E G R O U P m « l a s a n d t t o n t . m i t i > c o n g l o m t r « t t W A S E K W A N C R O U P m t l a s t d i m c n t a r y r o c k s W A S E K W A N C R O U P m . t i v o l c a m c l o e k t f i y / n a d l * fr Agassiz deposit ( m o d i f i e d a l l r i G i l b t r t el a\ 1980) F i g u r e 2.1 - R e g i o n a l G e o l o g y 16 m a f i c v o l c a n i c f l o w s a n d t u f f s , d a c i t e a n d g r e y w a c k e - s i l t s t o n e . T h e M a i n Z o n e of t h e m i n e i s c o m p r i s e d o f a s e r i e s o f s t e e p l y d i p p i n g , p a r a l l e l , t a b u l a r z o n e s o f o r e g r a d e m a t e r i a l c l o s e l y r e l a t e d to b e d s of a l t e r e d , c l a s t i c , b i o t i t i c s e d i m e n t s . ( F i e l d N a m e , T u f f a c e o u s S e d i m e n t s ) . T h e s e d i m e n t s o c c u r i n a n e x t e n s i v e h i g h m a g n e s i u m m a f i c u n i t ( F i e l d N a m e , C h l o r i t i z e d A n d e s i t e ) c o n s i s t i n g of a c t i n o l i t e - c h l o r i t e s c h i s t . T h e m a f i c r o c k s , w h i c h c o n t a i n b o t h s e d i m e n t a r y a n d v o l c a n i c f e a t u r e s , h o s t s o m e g o l d m i n e r a l i z a t i o n w h e n t h e y a r e s i l i c i f i e d , c a r b o n a t i z e d a n d m i n e r a l i z e d w i t h s u l p h i d e s . 2 . 3 S T R U C T U R A L G E O L O G Y A t t h e M i n e S i t e t h e W a s e k w a n G r o u p h a s b e e n f o l d e d i n t o a s t e e p l y i n c l i n e d s e q u e n c e d i p p i n g a t a p p r o x i m a t e l y 8 5 ° to t h e n o r t h . T h e i n t r u s i o n o f p l u t o n s h a s r e s u l t e d i n r e g i o n a l m e t a m o r p h i s m a n d a f o l i a t i o n w h i c h s t r i k e s r e g i o n a l l y a t a p p r o x -i m a t e l y n o r t h 4 5 ° e a s t a n d d i p s a t 8 5 ° t o t h e s o u t h e a s t ( F i g u r e 2 . 2 ) . - ^ W i t h i n t h i s s e q u e n c e t h e z o n e s of o r e g r a d e m a t e r i a l d i p a t a p p r o x i m a t e l y 8 5 ° t o t h e n o r t h . T h e o r e g r a d e m i n e r a l i z a t i o n i s t e r m i n a t e d to t h e n o r t h b y t h e N o r t h S h e a r ( F i g u r e 2 . 2 a n d 2 . 3 ) . T h i s s t r u c t u r e , c o n -s i s t i n g o f a 0 . 3 m e t r e to 6 . 0 m e t r e t h i c k z o n e o f s h e a r i n g , i s s u b - p a r a l l e l to t h e f o l i a t i o n , g e n e r a l l y s t r i k i n g a t a p p r o x i m a t e l y 1 8 F i g u r e 2 . 3 - G e o l o g i c a l C r o s s - s e c t i o n a t 0+00 E 19 N 5 0 ° E a n d d i p p i n g n e a r v e r t i c a l . It i s t h e mos t s i g n i f i c a n t s t r u c t u r e a t t h e s i t e . In a d d i t i o n to t h e N o r t h S h e a r , t h r e e s e t s of d i s c o n t i n u i t i e s a r e e v i d e n t . ^ 9 The m o s t c o m m o n s e t of d i s c o n t i n u i t i e s , s e t A , i s s u b p a r a l l e l t o t h e f o l i a t i o n , s t r i k i n g N 5 0 ° E a n d d i p p i n g a t 8 0 ° to 9 0 ° to t h e n o r t h w e s t a n d s o u t h e a s t . T h e s e c o n d mos t s i g n i f i c a n t j o i n t s e t , B , i s n e a r p e r p e n d i c u l a r to t h e f o l i a t i o n , s t r i k i n g a t N 4 0 ° W a n d d i p p i n g a t 8 0 ° t o 9 0 ° to t h e n o r t h e a s t a n d s o u t h w e s t . T h e t h i r d j o i n t s e t , C , c o n s i s t s o f r e l a t i v e l y f l a t - l y i n g j o i n t s d i p p i n g at 0 ° to 2 5 ° w i t h n o p r e f e r r e d s t r i k e d i r e c t i o n . A n e q u a l a r e a S c h m i d t s t e r e o n e t p l o t o f t h e s e t h r e e s e t s of d i s c o n t i n u i t i e s a n d t h e f o l i a t i o n i s g i v e n i n F i g u r e 2 . 4 . T h e p l o t t e d p o i n t s r e p r e s e n t t h e p e a k c o n c e n t r a t i o n o f t h e p o l e s to t h e j o i n t p l a n e s . 2 . 4 C O N C L U S I O N S T h e h o s t r o c k s s u r r o u n d i n g t h e o r e z o n e at t h e M c L e l l a n 20 F i g u r e 2 . 4 S t e r e o n e t P l o t o f S t r u c t u r a l D i s c o n t i n u i t i e s 21 M i n e c o n s i s t p r i m a r i l y o f c o m p e t e n t a n d e s i t i c r o c k s a n d t u f f a c e o u s s e d i m e n t s . T h e N o r t h S h e a r i s a m o r e b r o k e n , s h e a r e d i n t e r v a l o f s i m i l a r l i t h o l o g y . D u e to i t s b r o k e n n a t u r e a n d to t h e p r e s e n c e o f c l a y g o u g e , i t i s t h e s i n g l e mos t i m p o r t a n t g e o l o g i c a l f a c t o r t h a t w i l l a f f e c t t h e s t a b i l i t y o f t h e s t o p e s a t t h e M c L e l l a n M i n e , e s p e c i a l l y t h e h a n g i n g w a l l s of t h e s t o p e s . A s i t i s o f l i m i t e d t h i c k n e s s , p a r a l l e l to t h e s t o p e s a n d r e m o v e d f r o m t h e s t o p e w a l l s i n t h e v i c i n i t y of t h e s i l l p i l l a r , i t w i l l h a v e l i t t l e e f f e c t o n t h e s t a b i l i t y o f t h e s i l l p i l l a r . A l t h o u g h t h r e e s e t s o f d i s c o n t i n u i t i e s e x i s t w i t h i n t h e h o s t r o c k s , t h e y w i l l l i k e l y h a v e l i t t l e i m p a c t o n t h e o v e r a l l s t a b i l i t y o f t h e u n d e r g r o u n d e x c a v a t i o n s . A s t h e s e d i s c o n t i n u i t i e s a r e e i t h e r s u b - p a r a l l e l o r s u b - p e r p e n d i c u l a r to t h e s t o p e w a l l s o r a r e r e l a t i v e l y f l a t - l y i n g , w a v y a n d d i s c o n t i n u o u s , i t i s u n l i k e l y t h a t t h e y w i l l a f f e c t t h e s t a b i l i t y o f t h e s t o p e w a l l s o r t h e s i l l p i l l a r . It i s a n t i c i p a t e d t h a t t h e s e d i s c o n t i n u i t i e s w i l l h a v e a m i n i m a l e f f e c t o n t h e d i l u t i o n of o r e b y w a s t e r o c k . CHAPTER 3 HYDROGEOLOGY 23 3 .1 I N T R O D U C T I O N 3 . 1 . 1 S c o p e of t h e W o r k T h e h y d r o g e o l o g i c a l i n v e s t i g a t i o n o f t h e M c L e l l a n M i n e s i t e w a s i n i t i a t e d a t t h e r e q u e s t o f S h e r r i t t G o r d o n M i n e s L t d . o n J u l y 6 , 1 9 8 4 . T h e p u r p o s e o f t h e i n i t i a l p h a s e o f t h i s s t u d y w a s to i n v e s t i g a t e t h e s i g n i f i c a n c e o f t h e i n f l o w o f w a t e r i n t o t h e e x i s t i n g u n d e r g r o u n d w o r k i n g s at t h e s i t e , to p r o v i d e i n f o r m a t i o n , to f o r m u l a t e a m o r e d e t a i l e d s t u d y of t h e g r o u n d w a t e r c o n d i t i o n s a t t h e s i t e a n d t o a i d i n t h e r o c k m a s s c h a r a c t e r i z a t i o n of t h e m i n e . T h e p r o g r a m c o n s i s t e d o f a r e v i e w o f a l l a v a i l a b l e r e l e v a n t i n f o r m a t i o n a n d t h e m a p p i n g o f t h e s u r f a c e a n d u n d e r g r o u n d g r o u n d w a t e r c o n d i t i o n s . 3 . 1 . 2 C u r r e n t F i e l d W o r k T h e s i t e w o r k f o r t h e h y d r o g e o l o g i c a l s t u d i e s w a s c o m p l e t e d b e t w e e n J u l y 6 a n d 1 2 t h , 1 9 8 4 . D u r i n g t h i s p e r i o d t h e s u r f a c e a n d u n d e r g r o u n d g r o u n d w a t e r c o n d i t i o n s w e r e m a p p e d a n d a l l a v a i l a b l e d i a m o n d d r i l l c o r e l o g s w e r e r e v i e w e d . I n f o r m a t i o n 24 w a s a l s o c o l l e c t e d on t h e r e g i o n a l g e o l o g y , t h e s u r f i c i a l g e o l o g y , t h e e x t e n t of t h e o r e r e s e r v e s a n d t h e p r e s e n t m i n e d e v e l o p m e n t p l a n s . In a d d i t i o n , a r e v i e w o f t h e A t o m i c E n e r g y of C a n a d a L t d . ( A E C L ) p u b l i c a t i o n s ( 1 9 7 7 5 2 a n d 1979) o n g r o u n d w a t e r i n v e s t i g a t i o n s i n u n d e r g r o u n d m i n e s a n d e x c a v a t i o n s p r o v i d e d r e g i o n a l h y d r o g e o l o g i c a l i n f o r m a t i o n o f g r e a t v a l u e . T h e mos t t ime c o n s u m i n g t a s k of t h e d a t a c o l l e c t i o n p r o g r a m w a s t h e r e v i e w i n g of t h e d i a m o n d d r i l l c o r e l o g s a n d t h e r e d u c t i o n of t h i s i n f o r m a t i o n to a c o m m o n b a s e . E v e r y a v a i l a b l e l o g w a s r e v i e w e d to d e t e r m i n e t h e d e p t h to f r e s h , u n w e a t h e r e d b e d r o c k a n d to i d e n t i f y i n t e r s e c t i o n s of r o c k w i t h h i g h e r p e r m e a b i l i t y . F o r t h i s s t u d y a l l of t h e d r i l l i n g i n f o r m a t i o n h a s b e e n r e d u c e d t o a c o m m o n b a s e u s i n g t h e p r e s e n t b a s e l i n e to d e f i n e t h e g r i d a n d a s h a f t c o l l a r e l e v a t i o n of 1 5 2 4 . 7 6 m . 3 . 2 R E S U L T S 3 . 2 . 1 S u r f a c e M a p p i n g P r o g r a m T h e o v e r b u r d e n at t h e M c L e l l a n M i n e s i t e c o n s i s t s of a 25 r e l a t i v e l y c l e a n s a n d w i t h 2-3% s i l t o v e r l y i n g a z o n e of o x i d i z e d , w e a t h e r e d r o c k . T h e h y d r a u l i c c o n d u c t i v i t y o f t h e s e m a t e r i a l s i s l i k e l y i n t h e r a n g e of 1 x 1 0 " 2 to 1 x 1 0 " - ' c m / s e c . In t h i s r e l a t i v e l y p e r m e a b l e m a t e r i a l t h e g r o u n d w a t e r t a b l e i s e x p e c t e d t o a l a r g e d e g r e e , to r e f l e c t t h e g e n e r a l s u r f a c e of t h e u n d e r l y i n g u n w e a t h e r e d b e d r o c k . R e c h a r g e i n t o t h e l o c a l g r o u n d w a t e r s y s t e m i s o n l y f r o m i n f i l t r a t i o n f r o m t h e s u r f a c e o v e r t h e a r e a u n d e r s t u d y . D i s c h a r g e i s to t h e s o u t h w e s t to t h e K e e w a t i n R i v e r a n d to t h e s o u t h e a s t to J R L a k e . T h e r e s u l t s of t h e s u r f a c e m a p p i n g p r o g r a m a r e t a b u l a t e d i n A p p e n d i x I. T h e m e a s u r e m e n t o f t h e w a t e r l e v e l i n t h e s u r f a c e d r i l l h o l e s s e r v e s to c o n f i r m , i n a g e n e r a l s e n s e , t h a t t h e s u r f a c e of t h e g r o u n d w a t e r t a b l e i s g e n e r a l l y a s u b d u e d v e r s i o n o f t h e f r e s h r o c k s u r f a c e . T h e g r o u n d w a t e r t e n d s to f l o w a w a y f r o m t h e r i d g e u p o n w h i c h t h e h e a d f r a m e i s l o c a t e d ( F i g u r e 3 . 1 ) . A l i n e i n t e r s e c t i n g t h e h e a d f r a m e a n d H o l e 6 5 - 4 7 a p p e a r s t o a p p r o x i m a t e a n a t u r a l g r o u n d w a t e r d i v i d e . T o t h e e a s t o f t h i s l i n e t h e g r o u n d w a t e r f l o w i s to t h e s o u t h - e a s t ( a t a p p r o x i m a t e l y 4 5 ° to t h e b a s e l i n e ) , w h e r e a s to t h e w e s t of t h i s l i n e t h e f l o w i s t o w a r d t h e K e e w a t i n R i v e r . L o c a l l y t h e s e f l o w p a t t e r n s a p p e a r to b e i n f l u e n c e d b y p e r m a f r o s t a n d t o p o g r a p h i c h i g h s i n t h e u n w e a t h e r e d b e d r o c k s u r f a c e . If p e r m a f r o s t e x i s t s a t t h e s i t e , a s i n d i c a t e d b y t h e c o r e l o g s f o r h o l e s 55 -34 a n d 3 9 , c o n f i n e d a q u i f e r s i n t h e o v e r b u r d e n may c a u s e l ow a r t e s i a n f l o w s s u c h a s t h a t a t ho le A S 8 3 - 1 6 . F i g u r e s 3.1 - E s t i m a t e d T o p of F r e s h B e d r o c k S u r f a c e ( s o l i d ) and Groundwater t a b l e ( d a s h e d ) 27 T h e a r t e s i a n f l o w f r o m h o l e 8 0 - 6 a p p e a r s to b e t h e r e s u l t o f t o p o g r a p h i c c o n t r o l . 3 . 2 . 2 U n d e r g r o u n d M a p p i n g P r o g r a m T h e r e s u l t s of t h e u n d e r g r o u n d m a p p i n g p r o g r a m a r e t a b u l a t e d i n A p p e n d i x I I . It i s r e a d i l y o b v i o u s t h a t t h e i n f l o w s d u e to g e n e r a l s e e p a g e a r e e x t r e m e l y l o w , e v e n i n t h e s e c o n d l e v e l . I t w a s r a r e l y p o s s i b l e to i d e n t i f y t h e s t r u c t u r e a l o n g w h i c h t h e g e n e r a l s e e p a g e o c c u r s . H o w e v e r , i t w a s n o t e d t h a t t h e s e e p a g e f r o m t h e N o r t h S h e a r o n t h e T h i r d a n d 800 L e v e l s d o e s n o t n o t i c e a b l y d i f f e r f r o m t h e g e n e r a l s e e p a g e o n t h e s e l e v e l s . O n t h e S e c o n d L e v e l i t w a s n o t e d t h a t t h e i n f l o w s i n t h e c r o s s - c u t d r i f t b e t w e e n t h e m a i n d r i f t a n d t h e s h a f t , i n t h e a r e a b f t h e N o r t h S h e a r , a r e m u c h h i g h e r t h a n i n a n y o t h e r p o r t i o n of t h a t l e v e l . D u e to t h e w a t e r f l o w s f r o m t h e S e c o n d a n d T h i r d L e v e l s i n t o t h e s h a f t a n d t h e h i g h i n f l o w s f r o m t h e u p p e r 50 f ee t o f u n l i n e d s h a f t , t h e s h a f t i n f l o w s w e r e i m p o s s i b l e to i d e n t i f y . O n l y a r o u g h " g u e s s t i m a t e " of t h e t o t a l i n f l o w c o u l d b e o b t a i n e d . 28 In a d d i t i o n to t h e m a p p i n g o f t h e g e n e r a l w a t e r s e e p a g e i n t o t h e u n d e r g r o u n d o p e n i n g s t h e m o r e s i g n i f i c a n t f l o w s f r o m t w e n t y d r i l l h o l e s o n t h e S e c o n d L e v e l w e r e m e a s u r e d ( A p p e n d i x I I ) . M e c h a n i c a l w a t e r p a c k e r s w i t h g a t e v a l v e a s s e m b l i e s h a v e b e e n i n s t a l l e d i n mos t of t h e w a t e r p r o d u c i n g h o l e s o n t h i s l e v e l b u t t h r e e o f t h e g a t e v a l v e s t e m s h a v e b r o k e n a n d t h r e e of t h e h o l e s h a v e b e e n c o n n e c t e d to t h e m i n e w a t e r s u p p l y . T h e f l o w f r o m t h e s e s i x h o l e s w a s n o t m e a s u r e d . T h e p r o c e d u r e f o l l o w e d to m e a s u r e t h e f l o w f r o m t h e r e m a i n i n g h o l e s w a s t o : 1) O p e n a l l o f t h e v a l v e s to b e t e s t e d s t a r t i n g a t t h e w e s t e n d o f t h e ma in d r i f t p r o c e e d i n g to t h e e a s t e n d of t h e m a i n d r i f t . 2) Walk b a c k to t h e w e s t e n d o f t h e d r i f t a n d c o m m e n c e m e a s u r e m e n t of t h e i n f l o w s a f t e r a t ime i n t e r v a l o f a p p r o x i m a t e l y o n e h a l f h o u r . 3 ) A f t e r c o m p l e t i n g t h e m e a s u r e m e n t s t h e v a l v e s w e r e c l o s e d , s t a r t i n g a t t h e e a s t e n d a n d p r o c e e d i n g b a c k to t h e w e s t e n d . 29 T h e f o l l o w i n g d i r e c t o b s e r v a t i o n s w e r e a l s o m a d e : 1 ) A t t h e i n i t i a l t ime o f o p e n i n g t h e v a l v e , e a c h ho le p r o d u c e d i n f l o w s i n t h e o r d e r o f 50 t o 100 l i t r e s p e r m i n u t e . 2) In a l a r g e n u m b e r o f t h e t e s t e d h o l e s t h e f l o w r a t e d e c r e a s e d q u i c k l y to a r e l a t i v e l y l o w , s t a b l e f l o w . 3 ) T h e c l o s i n g o f t h e v a l v e s d i d n o t a f f e c t t h e i n f l o w r a t e s f r o m t h e r e m a i n i n g " o p e n " h o l e s e x c e p t f r o m t h e h o l e s d r i l l e d a t t h e s a m e d r i l l s t a t i o n . 4 ) B e t w e e n t h e t i m e o f m e a s u r e m e n t a n d t h e c l o s i n g o f t h e v a l v e t h e f l o w r a t e r e m a i n e d r e l a t i v e l y c o n s t a n t . 5 ) A t a n y g i v e n s t a t i o n t h e f l o w r a t e s w e r e g e n e r a l l y h i g h e s t i n t h e " u p - h o l e s " . 3 . 2 . 3 R e v i e w of C o r e L o g s T h e r e v i e w of a l l t h e a v a i l a b l e d i a m o n d d r i l l c o r e l o g s p r o v i d e d a l a r g e a m o u n t o f d a t a o n t h e e x t e n t of t h e o v e r b u r d e n a n d of t h e w e a t h e r e d b e d r o c k . In a d d i t i o n , z o n e s o f l o s t o r g r o u n d d r i l l c o r e a n d s h e a r e d , f a u l t e d a n d / o r b r e c c i a t e d i n t e r v a l s w e r e n o t e d . 30 T h e r e s u l t s o f t h i s r e v i e w a r e s u m m a r i z e d i n F i g u r e 3.1, w h i c h i s a p l a n s h o w i n g t h e c o n t o u r s o f t h e s u r f a c e o f t h e u n w e a t h e r e d b e d r o c k . N o c o r r e l a t i o n w a s o b t a i n e d b e t w e e n t h e f r a c t u r e d z o n e s e x c e p t f o r t h e i n t e r s e c t i o n s a t o r n e a r t h e N o r t h S h e a r . F o r t h i s r e a s o n t h e d a t a h a s no t b e e n p l o t t e d o n t h e p l a n . T h e c o n t o u r s of t h e u n w e a t h e r e d b e d r o c k s u r f a c e a r e , a t b e s t , a p p r o x i m a t i o n s of t h e r e a l c o n d i t i o n s a t t h e s i t e . H o w e v e r , i n t h i s c a s e t h e c o n t o u r s s h o u l d b e u s e d o n l y as a g u i d e . It s h o u l d b e r e m e m b e r e d t h a t t h e c o r e l o g s w e r e c o m p l e t e d f o r t h e s o l e p u r p o s e o f m i n e r a l e x p l o r a t i o n , no t f o r h y d r o l o g i c a l o r e n g i n e e r i n g s t u d i e s . A s a r e s u l t t h e l o g s o f t e n d o n o t c o n t a i n a n y d e t a i l r e g a r d i n g t h e e x t e n t a n d n a t u r e o f t h e o v e r b u r d e n o r o f t h e w e a t h e r e d b e d r o c k . In t h e s e c a s e s t h e t o p o f t h e u n w e a t h e r e d b e d r o c k w a s t a k e n to b e a t t h e b o t t o m o f t h e c a s i n g . T h e l o c a t i o n o f t h e b o t t o m o f t h e c a s i n g r e l a t i v e to t h e top o f t h e u n w e a t h e r e d r o c k i s a l s o c r i t i c a l . In t h e h o l e s t h a t a l o s s o f d r i l l i n g f l u i d w a s n o t e d , i t i s i m p o r t a n t to k n o w i f t h e c a s i n g w a s s e a t e d i n t o f r e s h b e d r o c k o r w i t h i n a s h o r t i n t e r v a l o f f r e s h r o c k ( s u c h as a b o u l d e r ) s u r r o u n d e d b y w e a t h e r e d m a t e r i a l . In a d d i t i o n , t h i s i n f o r m a t i o n c a n a l s o a f f e c t t h e i n t e r p r e t a t i o n of a r t e s i a n f l o w f r o m d r i l l h o l e s . 31 3 . 3 G E O H Y D R O L O G I C A L E N V I R O N M E N T 3 . 3 . 1 S u r f i c i a l H y d r o g e o l o g y A s c a n b e s e e n o n F i g u r e 3 .1 t h e s u r f a c e of t h e u n w e a t h e r e d b e d r o c k i s h i g h l y i r r e g u l a r . S e v e r a l t o p o g r a p h i c l o w s e x i s t i n t h e a r e a t h a t a r e n o t i n d i c a t e d b y t h e g r o u n d s u r f a c e . D e e p s u r f i c i a l d e p o s i t s a n d e x t e n s i v e z o n e s of w e a t h e r e d r o c k e x i s t i n t h e s e t o p o g r a p h i c l o w s . T h e h i g h h y d r a u l i c c o n d u c t i v i t y ( I O - 2 to IO"- 5 c m / s e c ) a n d p o r o s i t y ( i n t h e o r d e r o f 25 to 30%) ( F r e e z e a n d C h e r r y , 18) o f t h e s e m a t e r i a l s m a k e s t h e m s u s c e p t i b l e to " f l o w i n g s a n d " c o n d i t i o n s i f e n c o u n t e r e d i n u n d e r g r o u n d e x c a v a t i o n s . S e v e r a l o f t h e s e i n f i l l e d t o p o g r a p h i c l o w s m a y b e d r a i n a b l e f r o m t h e u n d e r g r o u n d w o r k i n g s . H o w e v e r , t h e d e p r e s s i o n s to t h e w e s t o f S e c t i o n - 1 2 0 E a l l a p p e a r to h a v e h y d r a u l i c c o n n e c t i o n t h r o u g h t h e s a n d to t h e K e e w a t i n R i v e r . W i t h o u t a m a j o r s u r f a c e g r o u t i n g p r o g r a m , i t i s d o u b t f u l t h a t t h e s e l o w s c o u l d b e d r a i n e d b e l o w a n e l e v a t i o n o f 1500 m . 32 3 . 3 . 2 B e d r o c k H y d r o q e o l o q y 3 . 3 . 2 . 1 L i t h o l o q y T h e b e d r o c k a t t h e M c L e l l a n M i n e s i t e c o n s i s t s o f a n d e s i t i c t u f f a n d f l o w r o c k s , a m p h i b o l i t e a n d t u f f a c e o u s s e d i m e n t s t h a t h a v e s u f f e r e d v a r i a b l e d e g r e e s of c h l o r i t i z a t i o n a n d a m p h i b o l i t i z a t i o n . A l s o a n u m b e r o f d y k e s o f a n d e s i t i c to d a c i t i c c o m p o s i t i o n h a v e b e e n i d e n t i f i e d i n t h e d i a m o n d d r i l l c o r e . 3 . 3 . 2 . 2 S t r u c t u r a l G e o l o g y T h e m o s t s i g n i f i c a n t s t r u c t u r e e v i d e n t f r o m t h e d i a m o n d d r i l l c o r e l o g s i s t h e N o r t h S h e a r . T h i s i s a n e a r v e r t i c a l f a u l t s t r i k i n g s u b - p a r a l l e l t o t h e o r e z o n e . O t h e r m i n o r f a u l t s e n c o u n t e r e d i n t h e d i a m o n d d r i l l h o l e s a r e p r o b a b l y a s s o c i a t e d w i t h t h i s f a u l t b u t t h e y d o n o t a p p e a r to b e c o n t i n u o u s w i t h d e p t h o r f r o m s e c t i o n to s e c t i o n . T h e d y k e s i n t e r s e c t e d i n t h e d r i l l h o l e s d o n o t a p p e a r to b e s i g n i f i c a n t i n a s t r u c t u r a l s e n s e . T h e y c a n n o t b e c o r r e l a t e d f r o m s e c t i o n to s e c t i o n o r w i t h z o n e s of b r e c c i a t i o n o r l o s t c o r e . H o w e v e r , t h e i n t e r s e c t i o n o f t h e d y k e s w i t h t h e N o r t h S h e a r may h a v e r e s u l t e d i n t h e t o p o g r a p h i c l o w s i n t h e f r e s h 33 b e d r o c k s u r f a c e . In a d d i t i o n t h e s e i n t e r s e c t i o n z o n e s may p r o v e to b e m o r e p e r m e a b l e t h a n t h e s u r r o u n d i n g r o c k s , e s p e c i a l l y n e a r t h e u n w e a t h e r e d b e d r o c k s u r f a c e . It i s a p p a r e n t f r o m t h e m a p p i n g of t h e u n d e r g r o u n d w o r k i n g s t h a t t h e ma jo r i n f l o w s o r i g i n a t e f r o m d i a m o n d d r i l l h o l e s d r i l l e d f r o m t h e S e c o n d L e v e l . H o w e v e r , a r e v i e w o f t h e o r i e n t a t i o n of t h e s e d r i l l h o l e s i n d i c a t e s t h a t a n u m b e r of t h e h o l e s w i t h t h e l a r g e r i n f l o w s ( g r e a t e r t h a n 9 l i t r e s / m i n ) h a v e b e e n d r i l l e d to w i t h i n l e s s t h a n 50 f ee t o f t h e e s t i m a t e d s u r f a c e of t h e f r e s h b e d r o c k . T h e r e m a i n i n g h o l e s w i t h l a r g e r i n f l o w s a p p e a r to p a s s v e r y c l o s e t o , o r e v e n i n t e r s e c t , d r i l l h o l e s c o m p l e t e d f r o m t h e s u r f a c e . W h e r e e x p o s e d in u n d e r g r o u n d w o r k i n g s t h e N o r t h S h e a r i s t i g h t a n d v i r t u a l l y d r y . T h e l a c k o f c o r r e l a t i o n o f z o n e s o f s h e a r i n g , b r e c c i a t i o n a n d c o r e l o s s , o t h e r t h a n t h e N o r t h S h e a r , i n d i c a t e s t h a t t h e e x i s t e n c e of a h i g h l y p e r m e a b l e , c o n t i n u o u s , f r a c t u r e d z o n e i s u n l i k e l y . T h e N o r t h S h e a r may b e r e l a t i v e l y p e r m e a b l e ( i n t h e r a n g e 1 X 1 0 t o 1 X 1 0 - 5 c m / s e c ) n e a r t h e s u r f a c e a n d i n d i s c o n t i n u o u s l e n s e s at d e p t h . H o w e v e r , i t d o e s n o t a p p e a r to r e p r e s e n t a m a j o r z o n e of h i g h p e r m e a b i l i t y . A n o t h e r d i s t i n c t s o u r c e o f w a t e r i n f l o w s to b e c o n s i d e r e d i s t h e q u a r t z v e i n s y s t e m . S u c h q u a r t z v e i n s c a n y i e l d h i g h f l o w s of w a t e r , h o w e v e r as t h e s e v e i n s d i s c o n t i n u o u s , a n y f l o w s e n c o u n t e r e d w i l l r a p i d l y to m i n o r l o n g t e r m i n f l o w s . 3 . 3 . 2 . 3 G e n e r a l H y d r o q e o l o q i c P r o p e r t i e s In a s t u d y of t h e s u r f a c e a n d s u b s u r f a c e s t r u c t u r a l a n d g r o u n d w a t e r c o n d i t i o n s a t s e l e c t e d u n d e r g r o u n d m i n e s a n d e x c a v a t i o n s i n t h e C a n a d i a n S h i e l d ( f o r t h e A E C L ) R a v e n a n d CO G a l e , L r e p o r t e d a g e n e r a l d e c r e a s e o f r o c k m a s s p e r m e a b i l i t y w i t h d e p t h a l t h o u g h l o c a l i z e d z o n e s of h i g h p e r m e a b i l i t y d i d e x i s t . Z o n e s w i t h h y d r a u l i c c o n d u c t i v i t y i n t h e r a n g e o f 1 X 1 0 " ! to 1 X 1 0 " ^ c m / s e c w e r e o f t e n a s s o c i a t e d w i t h o p e n j o i n t s , f a u l t s , b r e c c i a z o n e s a n d h i g h l y f r a c t u r e d a n d s h e a r e d d y k e s a n d s i l l s . T h e h y d r a u l i c c o n d u c t i v i t y o f a f a u l t z o n e w a s o c c a s i o n a l l y f o u n d to b e as l ow a s 1 0 " ^ to 1 0 " ^ c m / s e c , p o s s i b l y d u e to a l o w p e r m e a b i l i t y f a u l t g o u g e . G e n e r a l l y t h e r o c k m a s s p e r m e a b i l i t y r a n g e s f r o m 1 X 1 0 " 5 to 1 X 1 0 " ^ c m / s e c n e a r s u r f a c e to 1 X 1 C T 6 to 1 X 1 C T 8 c m / s e c a t d e p t h s o f a b o u t 200 t o 250 f e e t . T h e y a l s o f o u n d t h a t i n t h e a b s e n c e o f f a u l t s , s h e a r z o n e s , d y k e s a n d g e o l o g i c a l c o n t a c t s , v i s i b l e g r o u n d w a t e r s e e p a g e w a s s u b s t a n t i a l l y l o w e r a n d u s u a l l y r e s t r i c t e d to t h e u p p e r 30 m e t r e s of m i n e e x c a v a t i o n . In t h e n e a r s u r f a c e i t a p p e a r s t h a t g r o u n d w a t e r f l o w i n c r y s t a l l i n e r o c k o c c u r s t h r o u g h p r e f e r r e d f r a c t u r e s y s t e m s , s u g g e s t i n g h i g h l y a n i s o t r o p i c r o c k m a s s 34 a r e e r r a t i c a n d l i k e l y d e c r e a s e 35 T h e r a n g e o f p e r m e a b i l i t y v a l u e s d i s c u s s e d b y R a v e n a n d 5? G a l e ^ , a r e w e l l w i t h i n t h e n o r m f o r f r a c t u r e d i g n e o u s a n d m e t a m o r p h i c r o c k s r e p o r t e d b y F r e e z e a n d C h e r r y - * ^ . A t a b l e o f v a l u e s f r o m F r e e z e a n d C h e r r y i s i n c l u d e d i n A p p e n d i x I I I . 3 . 4 C O N C L U S I O N S A c o n t o u r map of t h e u n w e a t h e r e d b e d r o c k s u r f a c e h a s b e e n c o m p i l e d . T h e s e c o n t o u r s h a v e b e e n e s t i m a t e d f r o m d a t a d e r i v e d f r o m e x i s t i n g c o r e l o g s . B e c a u s e t h e c o r e l o g s w e r e w r i t t e n f o r t h e p u r p o s e of m i n e r a l e x p l o r a t i o n , t h e h y d r o g e o l o g i c a l i n f o r m a t i o n a v a i l a b l e f r o m t h e m i s o f l i m i t e d v a l u e i n d e t e r m i n i n g b e d r o c k c o n t o u r s . H o w e v e r t h e e s t i m a t e d c o n t o u r s c a n b e u s e d a s a g u i d e f o r t h e e x p l o r a t i o n of t h i s s u r f a c e d u r i n g t h e p e r i o d o f a c t i v e m i n i n g . W a t e r i n f l o w s p r e s e n t l y o c c u r r i n g i n t h e m i n e r a n g e f r o m l o c a l d r i p s to a t o t a l e s t i m a t e d i n f l o w o f 230 l i t r e s / m i n o n t h e 140 m L e v e l . It i s c o n c l u d e d t h a t t h e g r e a t e s t p o t e n t i a l f o r m a j o r w a t e r i n f l o w s a r i s i n g f r o m f u t u r e m i n i n g e x i s t s a l o n g t h e N o r t h S h e a r . H o w e v e r , i t i s u n l i k e l y t h a t a n y c o n f i n e d a q u i f e r c o n d i t i o n e x i s t s a t t h e s i t e . 36 T h i s e f f e c t w i l l b e mos t s i g n i f i c a n t i f t h e N o r t h S h e a r i s i n t e r s e c t e d b y u n d e r g r o u n d e x c a v a t i o n s w i t h i n some c r i t i c a l d i s t a n c e of t h e u n w e a t h e r e d b e d r o c k s u r f a c e . M o r e w o r k , i n t h e f o r m of c o m p u t e r m o d e l l i n g , i s n e e d e d to e s t i m a t e t h i s d i s t a n c e w h i c h i s t h o u g h t to b e i n t h e o r d e r of 30 m e t r e s . D u r i n g e x t r a c t i o n o f t h e o r e z o n e s as p r e s e n t l y l a i d o u t f o r m i n i n g i t i s u n l i k e l y t h a t a n y m a j o r p e r m e a b l e z o n e s w i l l b e i n t e r s e c t e d . H o w e v e r a t e s t i n g p r o g r a m i s a d v i s e d i n o r d e r to r u l e o u t t h e p o s s i b i l i t y o f m a j o r i n f l o w s . If t h e c u r r e n t m i n e p l a n s a r e f o l l o w e d , t h e w e s t e r n l im i t o f t h e w o r k i n g s w i l l b e u n d e r a t o p o g r a p h i c l ow i n t h e u n w e a t h e r e d b e d r o c k s u r f a c e . T h i s l o w i s h y d r a u l i c a l l y c o n n e c t e d to t h e K e e w a t i n R i v e r w h o s e e l e v a t i o n i s 1500 m e t r e s . A n y i n c r e a s e i n p e r m e a b i l i t y a s a r e s u l t o f m i n i n g o p e r a t i o n s a l o n g t h e N o r t h S h e a r i n t h i s v i c i n i t y c o u l d r e s u l t i n ma jo r w a t e r i n f l o w s . A n y f u t u r e m i n e d e v e l o p m e n t to t h e w e s t of S e c t i o n -150 E m a y h a v e to b e c o n f i n e d to l o w e r l e v e l s to m a i n t a i n a s a f e w o r k i n g d i s t a n c e b e t w e e n t h e o p e n i n g s a n d t h e s u r f a c e of t h e u n w e a t h e r e d b e d r o c k . I n f l o w s may b e e x p e c t e d f r o m i n d i v i d u a l q u a r t z v e i n s , w h i c h 37 c o u l d b e h i g h i n i t i a l l y . H o w e v e r , i t i s a n t i c i p a t e d t h a t i f t h e y o c c u r s u c h i n f l o w s w i l l d e c r e a s e r a p i d l y . A l i k e l y r a n g e of v a l u e s o f h y d r a u l i c c o n d u c t i v i t y c a n b e e s t i m a t e d at t h i s t i m e . T h e s e v a l u e s a r e l i s t e d b e l o w : 1 ) S a n d 1 0 - 2 t o 1 0 - 3 c m / s e c 2) W e a t h e r e d r o c k 1 0 - 4 to I O - 6 c m / s e c 3 ) G e n e r a l u n w e a t h e r e d 1 0 ~ 7 to 1 0 ~ 9 c m / s e c r o c k m a s s 4 ) N o r t h S h e a r b e t w e e n t h e 1 0 - 5 to 1 0 " ^ c m / s e c S e c o n d L e v e l a n d t h e u n w e a t h e r e d b e d r o c k s u r f a c e 5 ) N o r t h S h e a r b e l o w t h e 10 -6 to I O - 9 c m / s e c S e c o n d L e v e l W i th t h e low f l o w s a n d o n l y m o d e r a t e g r o u n d w a t e r p r e s s u r e s a n t i c i p a t e d i n t h e m i n e w o r k i n g s t h e e f f e c t o f t h e g r o u n d w a t e r c o n d i t i o n s o n m i n i n g c o n d i t i o n s a n d s t a b i l i t y o f t h e r o c k m a s s w i l l b e m i n i m a l . It i s a n t i c i p a t e d t h a t t h e h y d r a u l i c h e a d w i l l b e l e s s t h a n o n e f i f t h o f t h e m a j o r p r i n c i p a l s t r e s s . C H A P T E R 4 R O C K M A S S C H A R A C T E R I Z A T I O N 39 4 . 0 I N T R O D U C T I O N T h e r o c k m e c h a n i c s i n v e s t i g a t i o n of t h e M c L e l l a n M i n e c o m m e n c e d w i t h P h a s e I w o r k i n t h e a u t u m n o f 1 9 8 3 . T h e o v e r a l l o b j e c t i v e of t h e P h a s e I p r o g r a m w a s to i n v e s t i g a t e t h e q u a l i t y , b e h a v i o u r a n d m e c h a n i c a l p r o p e r t i e s of t h e r o c k u n i t s a t t h e M c L e l l a n M i n e . T h e p r o g r a m w a s l a t e r r e d e f i n e d i n t o f o u r o b j e c t i v e s : 1) E v a l u a t e t h e m e c h a n i c a l p r o p e r t i e s of e a c h l i t h o l o g i c a l u n i t ; 2) S e t u p a r o c k m a s s c l a s s i f i c a t i o n s c h e m e ; 3) E v a l u a t e s t r u c t u r a l c o n t r o l s o n s t a b i l i t y ; 4 ) I n v e s t i g a t e t h e N o r t h S h e a r Z o n e . O b j e c t i v e s 2) a n d 3) w e r e s a t i s f i e d w i t h t h e c o m p l e t i o n o f t h e r e p o r t " R o c k M e c h a n i c I n v e s t i g a t i o n at S h e r r i t t G o r d o n A g a s s i z M i n e , P h a s e I . " b y P o t v i n 4 9 . H o w e v e r , t h e r e s u l t s o f t h e w o r k a p p l y i n g to o b j e c t i v e s 1) a n d 4 ) , a n d t h e e s t a b l i s h m e n t of t h e r o c k m a s s c l a s s i f i c a t i o n s c h e m e i t s e l f w e r e p r e l i m i n a r y i n n a t u r e . Wi th t h e r e m a i n i n g f u n d s i n t h e r e s e a r c h g r a n t , w o r k c o n t i n u e d o n o b j e c t i v e s 1) a n d 2 ) . *Tn A u g u s t o f 1 9 8 5 , t h e name o f t h e m i n e w a s c h a n g e d f r o m " A g a s s i z M i n e " to M c L e l l a n M i n e . " 40 In J a n u a r y 1 9 8 5 , t h e w o r k p a s s e d f r o m P h a s e I i n v e s t i g a t i o n s to P h a s e II i n v e s t i g a t i o n s u n d e r w h i c h t h e f o l l o w i n g o b j e c t i v e s w e r e s p e c i f i e d : 1) D e t e r m i n a t i o n of f i e l d s t r e s s c o n d i t i o n s of t h e A g a s s i z M i n e . 2) T h e c o n t i n u a t i o n of i n v e s t i g a t i o n s i n t o t h e s p a t i a l v a r i a b i l i t y o f r o c k m a s s q u a l i t y a n d i n t a c t r o c k s t r e n g t h . 3 ) T h e a n a l y s i s of d a t a c o l l e c t e d u n d e r 1) a n d 2) b y n u m e r i c a l a n d a n a l y t i c a l m e t h o d s . T h i s C h a p t e r p r e s e n t s t h e r e s u l t s of w o r k c o m p l e t e d u n d e r I tem 2 , a n d r e l a t e s t h e r e s u l t s to t h e P h a s e I r e p o r t . 4 . 1 R O C K M A S S C L A S S I F I C A T I O N S Y S T E M S In 1984 P o t v i n a n d P a k a l n i s 5 0 c o m p l e t e d a d e t a i l e d l i t e r a t u r e r e v i e w w h i c h i d e n t i f i e d 33 r o c k m a s s c l a s s i f i c a t i o n s y s t e m s a n d d i s c u s s e d t h e i r r e l a t i v e m e r i t s . T h i s l i t e r a t u r e r e v i e w was l a t e r e x p a n d e d u p o n b y S h e r r i t t G o r d o n M i n e s L t d . 5 7 w h o p r o p o s e d t h a t " a u n i v e r s a l m i n e c l a s s i f i c a t i o n s h o u l d b e p a t t e r n e d a f t e r t h e " Q o r R M R " S y s t e m s w i t h t h e 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 e a c h m i n i n g m e t h o d i d e n t i f i e d . " 41 T h e s e f i n d i n g s c o r r o b o r a t e t h e s u g g e s t i o n b y H o e k a n d B r o w n i n 198025 t n a t t h e C S I R r a t i n g d e v e l o p e d b y B i e n i a w s k i ( R M R ) a n d t h e N G I s y s t e m d e v e l o p e d b y B a r t o n , L i e n a n d L u n d e ( Q ) w e r e t h e mos t p r o m i s i n g r o c k m a s s c l a s s i f i c a t i o n s y s t e m s i n u s e i n t h e d e s i g n of u n d e r g r o u n d o p e n i n g s . H o e k a n d B r o w n a l s o s t a t e d t h a t t h e y o f t e n u s e d b o t h s y s t e m s o n t h e same p r o j e c t f o r c o m p a r a t i v e p u r p o s e s a n d t h a t t h e r e l a t i o n s h i p b e t w e e n t h e s e t w o s y s t e m s c o u l d b e d e s c r i b e d b y : R M R = 9 l o g e Q +44 D u e to t h e l a r g e b a s e o f g e o t e c h n i c a l d a t a a v a i l a b l e f r o m t h e d i a m o n d d r i l l c o r e l o g s i t w a s d e c i d e d t h a t t h e C S I R s y s t e m w o u l d b e u s e d a t t h e M c L e l l a n M i n e S i t e . In a d d i t i o n , N G I r a t i n g s w e r e c o m p l e t e d o n s e l e c t e d d r i l l h o l e s t o p r o v i d e a c h e c k o n t h e R M R v a l u e s o b t a i n e d f r o m t h e C S I R c l a s s i f i c a t i o n s y s t e m . 42 4 . 2 R O C K M A S S C L A S S I F I C A T I O N 4 . 2 . 1 G e n e r a l D u r i n g t h e P h a s e I r o c k m e c h a n i c s i n v e s t i g a t i o n a t t h e M c L e l l a n M i n e , t h e d e s c r i p t i o n o f r o c k m a s s c h a r a c t e r i s t i c s was i n c o r p o r a t e d i n t o t h e c o r e l o g g i n g p r o c e d u r e s of t h e s i t e s t a f f . T h e s e d e s c r i p t i o n s f o r m e d t h e b a s i s of r o c k m a s s q u a l i t y r a t i n g s u s i n g t h e C S I R 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 f o r j o i n t e d r o c k ( H o e k a n d B r o w n , 1980) ( A p p e n d i x I V ) . R o c k m a s s r a t i n g s u m m a r i e s h a v e n o w b e e n c o m p l e t e d f o r 132 a d d i t i o n a l d i a m o n d d r i l l h o l e s w i t h i n t h e a r e a of i n t e r e s t t o t a l l i n g o v e r 1 7 , 0 0 0 m i n l e n g t h . 4 . 2 . 2 P r e v i o u s W o r k In t h e a u t u m n of 1 9 8 3 , r o c k m a s s r a t i n g s w e r e c o m p l e t e d f o r t w e n t y - s e v e n d i a m o n d d r i l l h o l e s t o t a l l i n g 3 , 0 0 0 f e e t o f c o r e . H o w e v e r , d r i l l c o r e w a s o n l y a v a i l a b l e f r o m t h e 1980 d i a m o n d d r i l l p r o g r a m . A s m u c h of t h i s d r i l l c o r e h a d b e e n p r e v i o u s l y s a m p l e d a n d s p l i t f o r a s s a y p u r p o s e s , t h e c o r e h a d b e e n s t o r e d o u t s i d e a n d s u b j e c t e d to n u m e r o u s f r e e z e - t h a w c y c l e s w h i c h h a d 43 i n d u c e d f u r t h e r f r a c t u r i n g . T h u s , t h e r e s u l t s w e r e c o n s e r v a t i v e ( T a b l e 4 . 1 ) . T a b l e 4 .1 V a r i a t i o n i n R o c k M a s s Q u a l i t y P h a s e I D e p a r t u r e R M R 152 mW - 30 mW 5 8 . 4 30 mW - 61 mE 4 7 . 8 61 mE - 152 mE 5 9 . 2 T h e r e s u l t s of t h i s w o r k i n d i c a t e d t h a t t h e r o c k q u a l i t y d o e s n o t v a r y w i t h d e p t h b u t d o e s v a r y w i t h d e p a r t u r e a s s h o w n i n T a b l e 4 . 1 . H o w e v e r , t h e s e r e s u l t s w e r e c o n s i d e r e d to b e p r e l i m i n a r y i n n a t u r e a n d b a s e d u p o n i n s u f f i c i e n t d a t a . R e c o m m e n d a t i o n s w e r e m a d e to c o n t i n u e t h i s w o r k i n t h e P h a s e II i n v e s t i g a t i o n s . 44 4 . 2 . 3 P h a s e II P r o c e d u r e s S i n c e t h e i n i t i a t i o n o f t h e r o c k m a s s c l a s s i f i c a t i o n l o g g i n g a t t h e M c L e l l a n s i t e , t h e c o r e f r o m a l l d i a m o n d d r i l l h o l e s h a v e b e e n g e o m e c h a n i c a l l y l o g g e d . S u m m a r y l o g s a n d c o m p u t e r d a t a f i l e s h a v e b e e n p r o d u c e d f o r 132 h o l e s w i t h i n t h e c u r r e n t a r e a o f i n t e r e s t . B e c a u s e t h e c o r e l o g g i n g i s c o m p u t e r i z e d at t h e M c L e l l a n s i t e , a l l d a t a h a s b e e n c o d e d . T h e c o d i n g s y s t e m a n d a s a m p l e d r i l l l o g a r e g i v e n i n A p p e n d i c e s V a n d V I . T h e s u m m a r i z i n g o f t h e r o c k m a s s r a t i n g s of t h e d r i l l c o r e w a s c o m p l e t e d f r o m c o m p u t e r p r i n t - o u t s of t h e d r i l l l o g s i n t h e f o l l o w i n g s e q u e n c e : 1) T h e d r i l l l o g w a s e x a m i n e d a n d i n t e r v a l s w i t h s i m i l a r d o m a i n , l i t h o l o g y a n d f r a c t u r e c h a r a c t e r i s t i c s w e r e i d e n t i f i e d 2) T h e i n d i v i d u a l r a t i n g p a r a m e t e r s w e r e a s s e s s e d a n d s u m m a r i z e d f o r e a c h i n t e r v a l i d e n t i f i e d ( A p p e n d i x V I I ) . 3 ) T h e t o t a l r a t i n g f o r e a c h i n t e r v a l w a s c a l c u l a t e d . 4 ) T h e b e g i n n i n g a n d e n d o f e a c h i n t e r v a l a n d t h e d o m a i n , l i t h o l o g y a n d r o c k m a s s r a t i n g w e r e e n t e r e d i n t o c o m p u t e r f i l e s a l o n g w i t h t h e d r i l l h o l e n u m b e r , c o l l a r c o - o r d i n a t e s a n d i n i t i a l s of t h e c o r e l o g g e r . 45 5 ) T h e c o m p u t e r f i l e s w e r e c o n v e r t e d i n t o a m o r e u s e f u l f o r m a t ( A p p e n d i x V I I I ) u s i n g t h e d o w n - h o l e d a t a to c a l c u l a t e a n d s t o r e : a) t h e d r i l l h o l e n u m b e r , b ) t h e l e n g t h o f t h e i n t e r v a l , c ) t h e d r i l l c o r e d i a m e t e r , d ) t h e c o - o r d i n a t e s o f t h e s t a r t a n d e n d p o i n t s of t h e i n t e r v a l , e) t h e d o m a i n , f ) t h e l i t h o l o g y , g ) t h e r o c k m a s s r a t i n g a n d h ) t h e i n i t i a l s of t h e c o r e l o g g e r . 6 ) T h e c o n v e r t e d c o m p u t e r f i l e s w e r e s c a n n e d f o r a p p r o p r i a t e d a t a to p r o v i d e s t a t i s t i c a l i n f o r m a t i o n o n t h e s p a t i a l v a r i a b i l i t y o f t h e r o c k m a s s r a t i n g s . 4 . 2 . 4 A s s e s s m e n t of R a t i n g P a r a m e t e r s A s s h o w n i n A p p e n d i x I V , t h e C S I R c l a s s i f i c a t i o n s y s t e m i n v o l v e s t h e a s s e s s m e n t o f f i v e 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 a r e s u m m e d to g i v e t h e r o c k m a s s r a t i n g . T h e s t r e n g t h p a r a m e t e r c a n b e a s s e s s e d u s i n g 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 t h e s a m p l e s o r b y m e a n s of P o i n t L o a d 46 t e s t s . Point Load tests of the diamond d r i l l core were rou t ine ly completed at r egu la r i n t e r va l s b y the McLe l lan Mine si te s ta f f . B e c a u s e the resu l t s were ava i lab le for a la rge number of these t e s t s , the Point Load s t r e n g t h tests were used to determine the s t r e n g t h ra t ing of each i n t e r v a l . The resu l t of a Po in t Load test r ep resen ts the load (P) r e q u i r e d to break a p iece of co re that is loaded at 90° to the co re a x i s . The Po in t Load Index (Hoek and B r o w n , 1983) is g i v e n b y : Is = P / D 2 where D = d iameter of the c o r e . The s t r e n g t h ra t i ng is de te rmined by the Po in t Load Index r a t h e r than the l o a d . A c o n v e r s i o n c h a r t f rom load to s t r e n g t h ra t i ng fo r A Q and B Q co re is g i ven in Table 4 . 2 . 47 T A B L E 4 . 2 S t r e n g t h P a r a m e t e r C o n v e r s i o n T a b l e P o i n t L o a d S t r e n g t h P o i n t C S I R P i n M P a L o a d S t r e n g t h A Q C o r e B Q C o r e I n d e x R a t i n g 4 . 0 + 7 . 4 + 8 + 15 2 . 0 t o 4 . 0 3 .7 to 7 . 4 4 - 8 12 1 .0 to 2 . 0 1.8 to 3 . 7 2 - 4 7 0 . 5 to 1.0 0 . 9 t o 1.8 1 - 2 4 0 . 0 to 0 . 5 0 . 0 to 0 . 9 0 - 1 1 T h e d r i l l c o r e q u a l i t y p a r a m e t e r i s d e p e n d e n t o n l y u p o n t h e R o c k Q u a l i t y D e s i g n a t i o n d e f i n e d b y D e e r e ( H o e k a n d B r o w n , 1 9 8 3 ) . T h e R o c k Q u a l i t y D e s i g n a t i o n ( R Q D ) i s t h e s u m o f t h e l e n g t h s of a l l c o r e p i e c e s g r e a t e r t h a n 4 " i n l e n g t h , f o r a g i v e n r u n , e x p r e s s e d as a p e r c e n t a g e of t h e t o t a l l e n g t h o f t h e r u n . T h e j o i n t s p a c i n g p a r a m e t e r w a s a s s e s s e d u s i n g t h e c o d i n g 48 f o r t h e f r a c t u r e f r e q u e n c y g i v e n i n t h e d r i l l l o g s ( A p p e n d i x I V ) . To d e t e r m i n e t h e s p a c i n g r a t i n g t h e c o m b i n e d e f f e c t s of a l l t h e f r a c t u r e s l o g g e d a r e a s s e s s e d a n d s u m m e d to y i e l d t h e s p a c i n g of t h e j o i n t s . F o r e x a m p l e , i f two j o i n t s e t s e x i s t , e a c h w i t h f r a c t u r e f r e q u e n c y of 1 , t h e r e i s a t o t a l o f 4 to 6 f r a c t u r e s p e r 3 m e t r e i n t e r v a l o r a j o i n t s p a c i n g i n t h e r a n g e of 0 . 5 to 0 . 7 5 m . T h e s p a c i n g i s t h e n a s s e s s e d a s b e i n g i n t h e r a n g e 0 . 3 to 1 m a n d h a s a r a t i n g of 2 0 . T h e j o i n t c o n d i t i o n p a r a m e t e r w a s a s s e s s e d o n a s u b j e c t i v e b a s i s f o r m e d f r o m t h e c o d e d c o r e l o g s a n d f r o m e x p e r i e n c e at t h e s i t e . D u r i n g t h e s p r i n g o f 1 9 8 5 , t h e w r i t e r i n s p e c t e d t h e u n d e r g r o u n d w o r k i n g s a n d a n u m b e r o f m e t r e s o f d r i l l c o r e , m a k i n g t h e f o l l o w i n g o b s e r v a t i o n s : 1 ) T h e j o i n t s a t t h e s i t e a r e i n v a r i a b l y s l i g h t l y r o u g h , s u b - p l a n a r , a n d g e n e r a l l y t i g h t a n d d i s c o n t i n u o u s . W h e r e s e r p e n t i n e e x i s t s o n t h e j o i n t s u r f a c e s , t h e j o i n t s a r e s l i c k e n s i d e d . J o i n t c o n d i t i o n r a t i n g = 2 0 . W h e r e s e r p e n t i n i z e d j o i n t c o n d i t i o n r a t i n g = 1 2 . 2 ) T h e f o l i a t i o n b r e a k s a r e g e n e r a l l y s l i g h t l y r o u g h to s l i c k e n s i d e d , u n d u l a t i n g , d i s c o n t i n u o u s a n d a r e w i t h i n c h l o r i t i z e d o r s e r p e n t i n i z e d b a n d s . J o i n t c o n d i t i o n r a t i n g = 1 2 . 3) T h e s h e a r b r e a k s a r e i n v a r i a b l y s l i c k e n s i d e d , s e l d o m 49 c o n t a i n m o r e t h a n 5 mm of g o u g e a n d a r e c o n t i n u o u s . J o i n t c o n d i t i o n r a t i n g = 6 . 4 ) W h e r e n e a r s u r f a c e , t h e f e a t u r e s l i s t e d i n 1 ) , 2) a n d 3) m a y b e o x i d i z e d a n d c o n t a i n s o f t , l i m o n i t i c c l a y . In t h i s e v e n t , t h e j o i n t c o n d i t i o n r a t i n g i s a s s e s s e d a t t h e n e x t l o w e r c l a s s . W h e n a s s e s s i n g t h e j o i n t c o n d i t i o n p a r a m e t e r f r o m t h e c o d e d c o r e l o g s , t h e w e a k e s t e x i s t i n g f e a t u r e w a s u s e d . O n t h e b a s i 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 , t h e g r o u n d w a t e r r a t i n g w a s a s s e s s e d a t 7 f o r a l l i n t e r v a l s . 4 . 2 . 5 R e s u l t s T h e a v e r a g e r o c k m a s s r a t i n g f o r e a c h l i t h o l o g i c a l u n i t a n d t h e r e l a t i v e d i s t r i b u t i o n o f t h e l i t h o l o g i c a l u n i t s i n e a c h d o m a i n a r e s u m m a r i z e d i n T a b l e 4 . 3 . A m o r e d e t a i l e d a n a l y s i s o f t h e v a r i a t i o n i n t h e r o c k q u a l i t y i n t h e h a n g i n g w a l l w i t h i n 10 m e t r e s o f t h e N o r t h S h e a r i s p r e s e n t e d g r a p h i c a l l y i n F i g u r e s 4 . 1 a n d 4 . 2 . D u e to t h e l i m i t e d a r e a o f i n t e r e s t w i t h i n t h e h a n g i n g w a l l , n o f u r t h e r d e t a i l w a s o b t a i n e d . A s t h e m a j o r i t y of t h e s t o p e w a l l s w i l l b e w i t h i n t h e f o o t w a l l , m o r e d e t a i l e d a n a l y s e s a r e m e r i t e d i n t h i s d o m a i n . In F i g u r e 4 . 3 , t h e v a r i a t i o n i n t h e r o c k m a s s r a t i n g i n t h e t u f f a c e o u s s e d i m e n t s i s p r e s e n t e d g r a p h i c a l l y i n a l o n g i t u d i n a l s e c t i o n . F i g u r e 4 . 4 i s a s i m i l a r p l o t o f r o c k m a s s q u a l i t y i n t h e c h l o r i t i z e d a n d e s i t e . F i g u r e 4 . 5 i s a p l o t o f r o c k m a s s r a t i n g i n t h e N o r t h S h e a r v s . d e p a r t u r e f o r i n t e r s e c t i o n s b e t w e e n 1 1 6 0 m a n d s u r f a c e . T h e v a r i a t i o n i n t h e r o c k m a s s r a t i n g w i t h d e p t h , b e t w e e n d e p a r t u r e s - 2 0 0 m a n d 2 0 0 m i s s h o w n i n F i g u r e 4 . 6 . T A B L E 4 . 3 S u m m a r y of R o c k M a s s R a t i n g s f o r E a c h D o m a i n D O M A I N L I T H O L O G I C A L U N I T | S M E T R E S U M M A R I Z E D % O F T O T A L R M R H a n g i n g - T u f f a c e o u s S e d i m e n t s 3 2 7 9 . 1 0 3 2 . 9 7 5 w a l l C h l o r i t i z e d A n d e s i t e 4 2 4 9 . 9 7 4 2 . 6 7 0 V a r i a b l e A n d e s i t e 1 2 4 4 . 5 7 1 2 . 5 7 0 A m p h i b . A n d e s i t e 1 0 3 . 1 0 1 . 0 7 7 A n d e s i t e 5 1 4 . 2 9 5 . 2 7 5 O t h e r 5 8 0 . 8 4 5 . 8 -T o t a l 9 9 7 1 . 8 7 1 0 0 . 0 7 2 F o o t w a l l T u f f a c e o u s S e d i m e n t s 2 4 8 2 . 6 0 3 6 . 7 7 7 C h l o r i t i z e d A n d e s i t e 3 6 5 0 . 1 1 5 4 . 0 7 4 V a r i a b l e A n d e s i t e 3 5 1 . 9 4 5 . 2 7 8 A m p h i b . A n d e s i t e 1 9 8 . 3 9 2 . 9 8 2 A n d e s i t e 7 . 8 0 0 . 1 7 5 O t h e r 7 6 . 2 0 1 . 1 -T o t a l 6 7 6 7 . 0 4 1 0 0 . 0 7 6 N o r t h S h e a r T u f f a c e o u s S e d i m e n t s 3 6 . 0 2 1 2 . 3 4 7 C h l o r i t i z e d A n d e s i t e 2 4 6 . 3 9 8 4 . 0 4 5 V a r i a b l e A n d e s i t e 9 . 5 5 3 . 3 4 9 A m p h i b . A n d e s i t e 0 . 7 2 0 . 2 5 6 A n d e s i t e - - -O t h e r 0 . 6 6 0 . 2 -T o t a l 2 9 3 . 3 4 1 0 0 . 0 4 5 51 4 . 2 . 6 D i s c u s s i o n A s d i s c u s s e d i n S e c t i o n 4 . 2 . 2 , t h e r o c k m a s s c l a s s i f i c a t i o n w o r k c o m p l e t e d u n d e r t h e P h a s e I i n v e s t i g a t i o n was no t c o m p l e t e d u n d e r i d e a l c i r c u m s t a n c e s . D u e to t h e t i m e l y g e o m e c h a n i c a l l o g g i n g of t h e d r i l l c o r e s b y S h e r r i t t G o r d o n p e r s o n n e l , a m u c h l a r g e r d a t a b a s e a n d m o r e r e a l i s t i c p i c t u r e of t h e r o c k q u a l i t y w a s o b t a i n e d f r o m t h e P h a s e II i n v e s t i g a t i o n s . In g e n e r a l , t h e r o c k m a s s r a t i n g s o b t a i n e d d u r i n g t h e P h a s e II i n v e s t i g a t i o n s a r e 15% to 20% h i g h e r t h a n t h o s e o b t a i n e d f r o m t h e P h a s e I i n v e s t i g a t i o n s . T h e r e s u l t s of t h e P h a s e I i n v e s t i g a t i o n a r e t h e r e f o r e d i s r e g a r d e d . In a d d i t i o n , a m u c h b e t t e r u n d e r s t a n d i n g o f t h e s p a t i a l v a r i a t i o n of t h e r o c k m a s s q u a l i t y h a s b e e n o b t a i n e d . T h u s , t h e r o c k m a s s r a t i n g of t h e t h r e e d o m a i n s , t h e h a n g i n g w a l l , t h e n o r t h s h e a r a n d t h e f o o t w a l l , h a s b e e n a n a l y z e d s e p a r a t e l y a n d / o r i n c o m p a r i s o n w i t h t h e o t h e r s . 4 . 2 . 6 . 1 H a n g i n g w a l l R o c k s W i t h i n t h e h a n g i n g w a l l r o c k s t h e r o c k m a s s r a t i n g s a r e g e n e r a l l y l o w e r n e a r t h e N o r t h S h e a r . In a d d i t i o n , t h e v a r i a t i o n i n r o c k m a s s q u a l i t y m o r e t h a n o n e s t o p e d i a m e t e r 52 b e y o n d a s t o p e w o u l d h a v e l i t t l e e f f e c t o n t h e r e a c t i o n of t h e s t o p e w a l l s to t h e e x c a v a t i o n . T h u s t h e s p a t i a l v a r i a t i o n of t h e r o c k m a s s q u a l i t y i n t h e h a n g i n g w a l l i s c o n f i n e d to t h o s e i n t e r v a l s w i t h i n 10 m e t r e s o f t h e N o r t h S h e a r . A l l d i s c u s s i o n o f t h e h a n g i n g w a l l r o c k s i s r e s t r i c t e d to t h i s a r e a . T h e r o c k m a s s r a t i n g o f t h e h a n g i n g w a l l r o c k s i s r e l a t i v e l y c o n s i s t e n t a t 70% to 75% b e l o w e l e v a t i o n 1460 m , ( F i g u r e 4 . 1 ) In t h e i n t e r v a l 1460 to 1500 m e l e v a t i o n , t h e r o c k m a s s r a t i n g a p p e a r s to d e c r e a s e to a p p r o x i m a t e l y 65%. A b o v e 1500 m e l e v a t i o n , t h e r o c k m a s s r a t i n g i s l e s s t h a n 50%. 48  65  64  70  NO DflTR  73  70  7 1 NO DflTR  75  73  73  74  73  72  72 7 1 0 20 40 60 80 100 • ROCK MHSS R A T I N G ( X ) o n I-> u _I 1 J C U 1500 1180 1468 1440 1420 1400 1380 1360 1340 1320 1300 1280 1260 1240 1220 1200 1180 l i e n F i g u r e 4 . 1 - R o c k M a s s R a t i n g v s . E l e v a t i o n - H a n g i n g w a l l R o c k s . 53 T h e r o c k m a s s r a t i n g s of t h e h a n g i n g w a l l r o c k s a p p e a r to b e w e a k l y z o n e d a l o n g t h e s t r i k e o f t h e N o r t h S h e a r ( F i g u r e 4 . 2 ) . W i t h i n t h e i n t e r v a l - 150 mE to 50 m E , t h e r o c k m a s s r a t i n g a v e r a g e s a p p r o x i m a t e l y 70%. E l s e w h e r e , t h e r o c k m a s s r a t i n g s a r e a b o v e 75%. T h e s e v a l u e s a r e c o n s e r v a t i v e d u e to t h e e f f e c t o f t h e l o w e r r o c k m a s s r a t i n g s o b t a i n e d a b o v e e l e v a t i o n 1460 m . F i g u r e 4 . 2 - R o c k M a s s R a t i n g v s . d e p a r t u r e - H a n g i n g w a l l R o c k s 4 . 2 . 6 . 2 F o o t w a l l R o c k s In t h e t u f f a c e o u s s e d i m e n t s , t h e r o c k m a s s r a t i n g i s g r e a t e r 54 t h a n 75% f o r 95% of t h e a r e a b e t w e e n e l e v a t i o n s 1160 a n d 1400 m . ( F i g u r e 4 . 3 ) . F r o m e l e v a t i o n 1400 m , t h e r o c k m a s s r a t i n g g e n e r a l l y d e c r e a s e s t o w a r d s t h e s u r f a c e w i t h a z o n e of c o m p a r a t i v e l y l o w e r r o c k q u a l i t y b e t w e e n -150 mE a n d 0 m E . H o w e v e r , d u e to a l a c k o f d a t a n e a r t h e s u r f a c e , t h e t r e n d s a r e no t w e l l d e f i n e d . In t h i s a r e a t h e v a l u e s a r e t h e r e s u l t o f i n t e r p r e t a t i o n o f g e n e r a l , n o n - g e o t e c h n i c a l d r i l l c o r e l o g s a n d c o r r e l a t i o n w i t h t h e h y d r o l o g i c a l s t u d i e s p r e s e n t e d i n C h a p t e r 3 . In t h e c h l o r i t i z e d a n d e s i t e , t h e r o c k m a s s r a t i n g i s g r e a t e r t h a n 70% f o r 80% o f t h e a r e a b e t w e e n e l e v a t i o n s 1160 a n d 1400 m . W i t h i n t h i s a r e a , t h e r o c k m a s s r a t i n g o f t h e c h l o r i t i z e d a n d e s i t e d o e s n o t f a l l b e l o w 60%. A b o v e e l e v a t i o n 1400 m , t h e r o c k m a s s r a t i n g g e n e r a l l y d e c r e a s e s t o w a r d s t h e s u r f a c e , w i t h z o n e s o f c o m p a r a t i v e l y h i g h e r r o c k q u a l i t y b e t w e e n -50 mE a n d OmE a n d b e t w e e n 100 mE a n d 200 m E . A s w i t h t h e t u f f a c e o u s s e d i m e n t s , t h i s i n t e r p r e t a t i o n i s b a s e d h e a v i l y u p o n c o r r e l a t i o n w i t h p r e v i o u s w o r k . 55 1520 1480 1440 1400 I3S0 W I) L. •» tl E w 1320 Z o n r -n > _j ui 1280 1240 1200 1160 GG 59 68 G4 73 69 7G 64 76 79 73 83 7 1 49 84 8 1 82 64 80 71 77 8 1 79 • 76 7B 75 79 75 72 7G 82 83 80 81 77 7G 77 73 79 85 82 80 73 75 ?a 84 80 B5 80 83 75 72 77 6 1 7S -200 -150 -100 -50 0 50 100 150 200 DEPRRTURE (metres) F i g u r e 4 . 3 - R o c k M a s s R a t i n g of T u f f a c e o u s S e d i m e n t s i n F o o t w a l l . 1520 1480 1440 1400 ^ 13G0 O 1 3 2 0 r -rx > 1280 Ul _ l Ul 1240 1200 1 1E0 53 69 59 82 57 70 61 79 60 G5 75 7 1 61 79 63 62 80 79 73 74 70 73 7G 77 74 79 77 7G 70 74 79 73 80 78 77 77 G7 G9 76 83 77 82 75 85 74 69 83 75 8 1 75 73 70 8 1 77 82 77 -200 -150 -100 -50 0 S0 DEPRRTURE (m) 100 150 F i g u r e 4 . 4 - R o c k M a s s R a t i n g of C h l o r i t i z e d A n d e s i t e i n F o o t w a l l • 56 4 . 2 . 6 . 3 N o r t h S h e a r W i t h i n t h e N o r t h S h e a r , t h e r o c k m a s s r a t i n g g e n e r a l l y i n c r e a s e s w i t h d e p t h . H o w e v e r , l i m i t e d d a t a i s a v a i l a b l e b e t w e e n e l e v a t i o n s 1360 m a n d 1440 m . T h e t r e n d i s t h e r e f o r e n o t c l e a r i n t h i s a r e a . B y c o m p a r i n g t h e a v a i l a b l e d a t a w i t h t h a t o b t a i n e d f r o m t h e H a n g i n g Wal l a n d t h e F o o t w a l l r o c k s , i t a p p e a r s t h a t t h e r o c k q u a l i t y i n t h e N o r t h S h e a r i s l i k e l y i n t h e r a n g e o f 25% to 30% a b o v e e l e v a t i o n 1400 m . A t o r n e a r 1400 m , t h e r o c k m a s s r a t i n g i n c r e a s e s to a p p r o x i m a t e l y 45%. T h i s a s s e s s m e n t i s v a l i d a t e d b y t h e r e s u l t s o f t h e p r e v i o u s h y d r o g e o l o g i c a l s t u d y . In t h a t i n v e s t i g a t i o n , i t w a s f o u n d t h a t i n some a r e a s , t h e r o c k s a r e i n t e n s e l y w e a t h e r e d w i t h l i m o n i t i c a l t e r a t i o n s w i t h i n j o i n t s a n d f a u l t s . W i t h i n t h e a r e a of i n t e r e s t , t h e s e w e a t h e r e d z o n e s r a r e l y e x t e n d e d b e l o w 1400 m e l e v a t i o n . L a t e r a l l y w i t h i n t h e N o r t h S h e a r , t h e r o c k m a s s q u a l i t y i s r e l a t i v e l y c o n s t a n t b u t b e t w e e n d e p a r t u r e s -200 m a n d -150 m , a n d b e t w e e n d e p a r t u r e s 100 m a n d 200 m , o n l y l i m i t e d d a t a i s a v a i l a b l e . E l s e w h e r e t h e r o c k m a s s r a t i n g g e n e r a l l y f a l l s i n t h e r a n g e of 40% to 50%. H o w e v e r , t h e s e v a l u e s a r e a f f e c t e d b y t h e l ow r o c k m a s s r a t i n g s a b o v e e l e v a t i o n 1400 m . 57 F i g u r e 4.5 - R o c k M a s s R a t i n g v s . E l e v a t i o n - N o r t h S h e a r . 100 2 cr or tn to cc u o G 0 •40 2 0 46 44 AB 45 42 47 50 43 - 2 0 0 - 1 5 0 - 1 0 0 - 5 0 0 5 0 1 0 0 1 5 0 2 0 0 DEPRRTURE (m) F i g u r e 4.6 - R o c k M a s s R a t i n g v s . D e p a r t u r e - N o r t h S h e a r . 58 4 . 2 . 6 . 4 E s t i m a t e d I n - S i t u S t r e n g t h C h a r a c t e r i s t i c s In o r d e r to a n a l y z e t h e o v e r a l l s t a b i l i t y o f t h e m i n e o p e n i n g s a n d o f t h e s i l l p i l l a r t h e i n - s i t u p r o p e r t i e s of t h e r o c k m a s s m u s t b e e s t i m a t e d . H o e k a n d B r o w n 2 ^ d e v e l o p e d an e m p i r i c a l r e l a t i o n s h i p b e t w e e n t h e p r i n c i p a l s t r e s s e s a s s o c i a t e d w i t h t h e f a i l u r e o f i n t a c t r o c k w h i c h h a s s i n c e g a i n e d a c c e p t a n c e a n d b e e n m o d i f i e d 24 b y H o e k ^ . T h i s r e l a t i o n s h i p d e f i n e s t h e s t r e n g t h o f r o c k o n t h e b a s i s o f t h e c o n f i n i n g s t r e s s , 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 t h e i n t a c t r o c k a n d t h e m a t e r i a l c o n s t a n t s , m a n d s , d e f i n e d b y t h e r o c k m a s s r a t i n g . ( T a b l e 4 . 4 ) . T h e r e l a t i o n s h i p i s d e f i n e d b y t h e e q u a t i o n : 0^ = 0 3 + mcrc03 + scr^2 w h e r e CT\ - m a j o r p r i n c i p a l s t r e s s a t f a i l u r e 03 = m i n o r p r i n c i p a l s t r e s s a t f a i l u r e rrc = 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 s a m p l e s . m , s = m a t e r i a l c o n s t a n t s d e f i n e d i n T a b l e 4 . 4 . B a s e d o n T a b l e 4 . 4 a n e s t i m a t e o f t h e m a t e r i a l c o n s t a n t s , m a n d s , c a n b e m a d e f o r t h e r o c k s a n d m i n i n g c o n d i t i o n s a t t h e M c L e l l a n M i n e . . „ , -,i : ,ra & s Valuee Cor d i s t r i b u t e d rock, uasses m & a Values for undistributed rock masses 59 Empirical failure criterion °1 "3 in, e - major p r i n c i p a l BtreBS - minor p r i n c i p a l s t r e s s - u n i a x i a l compressive s t r e n g t h of i n t a c t rock, and e m p i r i c a l c o n s t a n t s . to 1 •u "3 3 3 K a* 3 l o S ss P< 9 °, S3 •8 M Q O Vt •1 J s 1 8 M So •8 i in t o f 8 a u PS w M g-8 m S> o 5 I' 1 1 10 o •8 •« o 53-8 INTACT ROCK SAMPLES Laboratory eiae specimens free from joints CSIR r a t i n g 100 NGI r a t i n g 500 m - 7.0 m - 10.0 a - 1.0 a - 1.0 m - 7.0 m r 10.0 15.0 1.0 8 1.0 e 1.0 m " 15.0 B - 1.0 m - 17.0 m - 25.0 a - 1.0 a - 1.0 m •= 17.0 m = 25.0 e - 1.0 8 = 1.0 VERY GOOD QUALITY ROCK MASS Tightly interlocking undis-turbed rock with unweathered joints at 1 to 3m. CSIR r a t i n g 85 NGI r a t i n g 100 m - 3,5 s - 0.1 m " 5.0 s -=0.5 m - 5.0 s - 0.1 m - 7.5 e = 0.5 m - 7.5 B - 0.1 m - 10.0 e - 0 . 5 s 8.5 0. 1 m s 12.5 0. 1 m - 15.0 I m - 17.0 s - 0.5 1 8 = 0.5 GOOD QUALITY ROCK MASS Freeh to elightly weathered rock, elightly disturbed with joints at 1 to 3m. CSIR r a t i n g 65 NGI r a t i n g 10 ra - 0. 7 s - 0.004 m = 3. 5 8 = 0.1 m - 1.0 a - 0.004 5.0 0.1 m - 1.5 • - 0.004 m - 7.5 8 - 0 . 1 m - 1.7 | m - 2.5 e - 0.0041 s - 0.004 m 8 8.5 0.1 m - 12.5 e = 0.1 FAIR QUALITY ROCK MASS Several sets of moderately weathered joints epaced at 0. 3 to lm. m - 0.14 s - 0.0001 CSIR r a t i n g NGI r a t i n g 44 1 0. 7 0.004 0.20 ra - 0.30 0.0001 a - 0.000 1.0 m - 1.6 0.004 8 - 0.004 m - 0.34 1 m - 0.50 8 - 0.000)1 a - 0.000 m - 1.7 I m - 2.5 8 - 0.004 1 e - 0.004 POOR QUALITY ROCK MASS Numerous weathered joints at 30 to 600mm with eome gouge. Clean compacted waste rock. CSIR r a t i n g 23 NGI r a t i n g 0.1 m - 0.04 s-0.00001 m = 0. 14 8 = 0.0001 m - 0.05 a-0.00001 m = 0.20 8 - 0.0001 m - 0.08 a-0.00001 m - 0.09 | ra - 0.13 a-0.00001 I s-0.00001 m a 0.30 0.0001 m - 0.34 | m e - 0.0001 0.50 0.0001 VERY POOR QUALITY ROCK MASS Numerous heavily weathered joints epaced < 50mm with gouge. Waste rock with fines. CSIR r a t i n g 3 NGI r a t i n g 0.01 m - 0.007 s - 0 •n = 0.04 s=0.00001 0.01 0 0.01 0 m - 0.017 s - 0 m - 0.025 a - 0 m = 0.05 s^O.00001 m - 0.08 e=0.00001 m - 0.09 | m - 0.13 e~0.QQfl&l. s^O.00001 T a b l e 4 . 4 - A p p r o x i m a t e R e l a t i o n s h i p B e t w e e n R o c k M a s s Q u a l i t y a n d M a t e r i a l C o n s t a n t s ( A f t e r H o e k ) 2 4 . 60 T h e r o c k s i n t h e f o o t w a l l a n d h a n g i n g w a l l b e l o w e l e v a t i o n 1400 m h a v e a r o c k m a s s r a t i n g c o n s i s t e n t l y i n t h e r a n g e of 65% to 80% a n d a n a v e r a g e r a t i n g of a p p r o x i m a t e l y 75%. T h e r o c k s c o n s i s t o f s i l i c i f i e d f o l i a t e d a n d e s i t i c r o c k s a n d t u f f a c e o u s s e d i m e n t s . In a d d i t i o n , w i t h t h e c u t - a n d - f i l l m i n i n g m e t h o d t h e s t o p e w a l l s a n d p i l l a r s w i l l n o t b e s u b j e c t e d to h e a v y b l a s t d a m a g e . A s t h e b l a s t i n g a l w a y s t a k e s p l a c e w i t h two f r e e f a c e s , t h e r o c k s i n t h e s t o p e w a l l s a n d a d j a c e n t p i l l a r s s h o u l d b e r e l a t i v e l y u n d i s t u r b e d . T h e m a t e r i a l c o n s t a n t s f o r t h e s e r o c k s a r e t h e r e f o r e a s s e s s e d a t : m = 1 0 . 0 s = 0 . 5 In t h e N o r t h S h e a r t h e m a t e r i a l c o n s t a n t s a r e m a r k e d l y l o w e r a t : m = 0 . 5 s = 0 . 0 0 0 1 61 A b o v e e l e v a t i o n 1400 m t h e m a t e r i a l c o n s t a n t s a r e e s t i m a t e d a t : m = 7 . 5 s = 0 .1 f o r t h e h a n g i n g w a l l a n d f o o t w a l l r o c k s , a n d , m = 0 . 5 0 s = 0 . 0 0 0 1 f o r t h e N o r t h S h e a r . In a d d i t i o n to t h e m a t e r i a l c o n s t a n t s , a r e l a t i o n s h i p b e t w e e n t h e i n - s i t u d e f o r m a t i o n m o d u l u s o f r o c k m a s s e s a n d r o c k m a s s r a t i n g s d e v e l o p e d b y B i e n i a w s k i i s r e c o m m e n d e d b y H o e k a n d B r o w n 2 ^ . T h i s r e l a t i o n s h i p , a s p r e s e n t e d i n F i g u r e 4 . 7 p r o v i d e s a g o o d e s t i m a t e o f t h e i n - s i t u d e f o r m a t i o n m o d u l u s o f t h e r o c k s a t t h e M c L e l l a n M i n e . F r o m t h i s f i g u r e i t i s e s t i m a t e d t h a t t h e i n - s i t u d e f o r m a t i o n m o d u l u s of h a n g i n g w a l l a n d f o o t w a l l r o c k s i s 50 G P a . A b o v e e l e v a t i o n 1400 m a n d i n t h e N o r t h S h e a r t h e m o d u l u s i s e s t i m a t e d at a p p r o x i m a t e l y 1 0 G P g . 62 F i g u r e 4 . 7 - R e l a t i o n s h i p B e t w e e n I n - s i t u D e f o r m a t i o n m o d u l u s o f R o c k M a s s e s a n d R o c k M a s s C l a s s i f i c a t i o n . ( A f t e r B i e n i a w s k i f r o m H o e k a n d B r o w n ) 25 63 4 . 2 . 6 . 5 E s t i m a t e d S t a n d - u p T i m e s U s i n g t h e e m p i r i c a l r e l a t i o n s h i p b e t w e e n s t a n d - u p t ime a n d t h e r o c k m a s s r a t i n g p r o p o s e d b y B i e n i a w s k i , a s s h o w n i n F i g u r e 4 . 8 , t h e s t a n d - u p t i m e s f o r u n s u p p o r t e d s p a n s w e r e e s t i m a t e d . T h e r e s u l t s o f t h i s w o r k a r e p r e s e n t e d i n T a b l e 4 . 5 STAND-UP TIME - HOURS F i g u r e 4 . 8 R e l a t i o n s h i p B e t w e e n t h e S t a n d - u p T i m e o f a n U n s u p p o r t e d s p a n a n d R o c k M a s s R a t i n g . ( A f t e r B i e n i a w s k i f r o m H o e k a n d B r o w n ) 25 64 T a b l e 4 . 5 E s t i m a t e d S t a n d - u p T i m e f o r U n s u p p o r t e d S p a n s D o m a i n L i t h U n s u p p o r t e d L o w S t a n d - u p H i g h S t a n d - u p U n i t s S p a n R M R T i m e R M R T i m e HW A L L 4 m 55% 10 d a y s 75% 8 m o s . N S A L L 3 m 25% 0 45% 2 d a y s 4 m 25% 0 45% 2 d a y s F W T S 3 m 75% 9 m o s . 5 m 75% 8 m o s . 10 m 75% 6 m o s . 20 m 75% 0 F W C A 3 m 60% 1 m o n t h 70% 5 m o s . 5 m 60% 25 d a y s 70% 4 m o s . 10 m 60% 15 d a y s 70% 3 m o s . 20 m 60% 0 70% 0 65 A l t h o u g h t h e s t a n d - u p t i m e s a r e o n l y o r d e r o f m a g n i t u d e e s t i m a t e s , t h e y a r e h e l p f u l i n o u t l i n i n g t h e p r o b l e m a r e a s . T a b l e 4 . 5 i n d i c a t e s t h a t some i m m e d i a t e l o o s e n i n g a n d r a v e l l i n g may o c c u r i n t h e s t o p e r o o f s w h e r e v e r t h e s t o p e w i d t h e x c e e d s 20 m e t r e s . In t h e f o o t w a l l r o c k s , t h e s t o p e w a l l s a n d r o o f s l e s s t h a n 20 m e t r e s w i d e w i l l l i k e l y s t a n d u p f o r t h e d u r a t i o n of e a c h c u t - a n d - f i l l c y c l e . W h e r e t h e r o c k m a s s r a t i n g i s l e s s t h a n 60%, t h e r o o f w i l l l i k e l y e x p e r i e n c e s o m e l o o s e n i n g a n d r a v e l l i n g p r i o r to t h e c o m p l e t i o n o f e a c h c u t . W h e r e v e r t h e N o r t h S h e a r i s e x p o s e d i n t h e s t o p e w a l l s a n d r o o f s , s i g n i f i c a n t d i l u t i o n i s l i k e l y to o c c u r d u e to t h e e x t r e m e l y s h o r t s t a n d - u p t i m e . D e t a i l e d r e m e d i a l m e a s u r e s f o r s u p p o r t i n g t h e m i n e w o r k s w i l l b e d i s c u s s e d i n l a t e r c h a p t e r s d e a l i n g w i t h m i n e d e s i g n p a r a m e t e r s . 66 4 . 3 D E T A I L E D I N V E S T I G A T I O N OF T H E N O R T H S H E A R In c o n s i d e r a t i o n o f t h e s t r u c t u r a l s i g n i f i c a n c e o f t h e N o r t h S h e a r a n d l o w e r r o c k m a s s r a t i n g s c o m p a r e d to t h e H a n g i n g -w a l l a n d F o o t w a l l r o c k s , a d d i t i o n a l d e t a i l e d s t u d i e s w e r e c o m p l e t e d o n t h e N o r t h S h e a r . A c o m p l e t e r e v i e w o f t h e d i a m o n d d r i l l c o r e l o g s o f h o l e s c o m p l e t e d f r o m t h e u n d e r g r o u n d w o r k i n g s i n 1984 a n d 1985 w a s u n d e r t a k e n to d e t e r m i n e t h e s p a t i a l r e l a t i o n s h i p b e t w e e n t h e N o r t h S h e a r a n d t h e e c o n o m i c o r e z o n e s . In a d d i t i o n , t h e s t o p e p l a n s o b t a i n e d i n M a y , 1985 w e r e r e v i e w e d i n t h e s a m e c o n t e x t . 4 . 3 . 1 P r o c e d u r e In r e v i e w i n g t h e d i a m o n d d r i l l c o r e l o g s , t h e r o c k t y p e s a n d t h e a s s a y r e s u l t s i n t h e N o r t h S h e a r a n d a d j a c e n t F o o t w a l l r o c k s w e r e c o m p i l e d to s t u d y t h e p r o x i m i t y o f t h e N o r t h S h e a r t o t h e e c o n o m i c z o n e s . In a d d i t i o n , t h e t r u e t h i c k n e s s o f e a c h d r i l l h o l e i n t e r s e c t i o n w i t h t h e N o r t h S h e a r a n d s u r r o u n d i n g f r a c t u r e d r o c k w a s e s t i m a t e d . T h e r e v i e w o f t h e s t o p e p l a n s c o n s i s t e d o f e s t i m a t i n g t h e l e n g t h o f t h e h a n g i n g w a l l o f e a c h s t o p e t h a t c o u l d b e a f f e c t e d b y t h e N o r t h S h e a r . T h e s e e s t i m a t e s w e r e b a s e d u p o n t h e 67 f o l l o w i n g a s s u m p t i o n s : 1 ) W h e r e e c o n o m i c g r a d e s e x i s t w i t h i n t h e N o r t h S h e a r , t h e N o r t h S h e a r w i l l b e m i n e d o u t ; 2) W h e r e n e a r e c o n o m i c g r a d e s , .08 o z / t o n o r m o r e , e x i s t w i t h i n t h e N o r t h S h e a r , d i l u t i o n w i l l n o t b e s i g n i f i c a n t ; 3 ) W h e r e t h e N o r t h S h e a r i s m o r e t h a n t h r e e m e t r e s f r o m t h e h a n g i n g w a l l o f t h e s t o p e , i t w i l l l i k e l y h a v e l i t t l e e f f e c t u p o n t h e r e a c t i o n o f t h e s t o p e w a l l s to m i n i n g . E s t i m a t e s w e r e c o m p l e t e d o n i n t e r v a l s o f 20 m e t r e s e l e v a t i o n b e t w e e n e l e v a t i o n 1160 m a n d e l e v a t i o n 1380 m . A . 3 . 2 R e s u l t s T h e d a t a c o m p i l e d f r o m t h e r e v i e w o f t h e d i a m o n d d r i l l c o r e l o g s i s g i v e n i n A p p e n d i x I X . O f t h e 119 d r i l l h o l e c o r e l o g s r e v i e w e d , o n l y 44 h o l e s i n t e r s e c t i n g t h e N o r t h S h e a r d i d no t mee t t h e r e q u i r e m e n t s g i v e n i n S e c t i o n 4 . 3 . 1 . O n l y 30 i n t e r s e c t i o n s o r a p p r o x i m a t e l y 25% o f t h e t o t a l c o n t a i n e d m o r e t h a n 1.0 m e t r e o f m a t e r i a l g r a d i n g l e s s t h a n 0 . 0 8 o z / t o n . T h e d a t a o b t a i n e d f r o m t h e s t o p e p l a n s i n d i c a t e s t h a t a p p r o x i m a t e l y 60% of t h e t o t a l a r e a o f t h e h a n g i n g w a l l s of t h e s t o p e s w i l l b e f o r m e d b y o r w i l l b e w i t h i n t h r e e m e t r e s of t h e N o r t h S h e a r . 68 4 . 3 . 3 D i s c u s s i o n A l t h o u g h t h e r e v i e w of t h e d r i l l ho l e c o r e l o g s p r o d u c e d m u c h m o r e a c c u r a t e d a t a , t h e r e l a t i v e s p a c i n g a n d " w e i g h t " o f e a c h d a t a p o i n t w a s no t i n v e s t i g a t e d . T h u s , t h e p e r c e n t a g e of t h e h a n g i n g w a l l s o f t h e s t o p e s a f f e c t e d b y t h e N o r t h S h e a r c o u l d b e m u c h l a r g e r t h a n i n d i c a t e d b y t h i s r e v i e w . It i s l i k e l y t h a t t h e p e r c e n t a g e o f t h e h a n g i n g w a l l a f f e c t e d b y t h e N o r t h S h e a r i s i n t h e o r d e r o f 50% of t h e t o t a l a r e a of t h e h a n g i n g w a l l s . 69 4 . 4 U N I A X I A L C O M P R E S S I V E T E S T S 4 . 4 . 1 P r e v i o u s Work In t h e P h a s e I i n v e s t i g a t i o n s , u n i a x i a l c o m p r e s s i v e t e s t s w e r e c o m p l e t e d o n 46 s a m p l e s o f N X d i a m o n d d r i l l c o r e . T h e n u m b e r of s a m p l e s f r o m e a c h l i t h o l o g i c a l u n i t a n d t h e a v e r a g e c a l c u l a t e d t e s t r e s u l t s f o r e a c h u n i t a r e s u m m a r i z e d i n T a b l e 4 . 6 . T a b l e 4 . 6 R e s u l t s of P h a s e I T e s t s L i t h o l o g i c a l U n i t Mo. o f S a m p l e s U c s ( M P a ) E ( M P a x l O 3 ) T u f f S e d i m e n t a r y C h l o r i t i z e d A m p h i b A n d e s i t e C h l o r i t i z e d A n d e s i t e A n d e s i t e V a r i a b l e A n d e s i t e 15 16 7 6 3 9 2 . 8 3 5 0 . 4 5 9 3 . 6 0 1 3 4 . 4 0 8 6 . 9 7 26 17 ^ R e s u l t s too i n c o n s i s t e n t o r i n a d e q u a t e to c a l c u l a t e a v e r a g e s . 70 B e c a u s e of t h e l ow p e r c e n t a g e of v a r i a b l e a n d e s i t e a n d a n d e s i t e s a m p l e s t h a t w e r e t e s t e d c o m p a r e d to t h e c h l o r i t i z e d a n d e s i t e a t t h e s i t e a n d t h e s i m i l a r e n g i n e e r i n g c h a r a c t e r i s t i c s o f t h e s e u n i t s , t h e t h r e e u n i t s w e r e g r o u p e d t o g e t h e r as c h l o r i t i z e d a n d e s i t e . A s t h e r e s u l t s f o r t h e E l a s t i c M o d u l u s a n d t h e P o i s s o n ' s R a t i o f o r t h i s u n i t w e r e too i n c o n s i s t e n t a d d i t i o n a l t e s t s w e r e c o m p l e t e d . 4 . 4 . 2 S a m p l e P r e p a r a t i o n T h e s a m p l e s f o r t h e u n c o n f i n e d c o m p r e s s i v e t e s t s w e r e o b t a i n e d f r o m l a r g e b l o c k s t a k e n f r o m t h e S e c o n d L e v e l o f t h e M c L e l l a n M i n e i n t h e s p r i n g of 1 9 8 4 . T h e s a m p l e s w e r e p r e p a r e d f o r t e s t i n g a s f o l l o w s : 1) B Q ( 4 6 . 5 mm) d i a m o n d d i l l c o r e s a m p l e s w e r e o b t a i n e d f r o m t h e b l o c k s u s i n g t h e c o r i n g m a c h i n e i n t h e M M P E D e p a r t m e n t a t U . B . C . , t a k i n g c a r e to p r e v e n t a b r u p t i r r e g u l a r i t i e s a l o n g t h e s i d e s of t h e s a m p l e s . 2 ) T h e s a m p l e s w e r e c u t to a h e i g h t to d i a m e t e r r a t i o b e t w e e n 2 . 2 a n d 2 . 7 . 3 ) T h e e n d s o f t h e s a m p l e s w e r e l a p p e d s m o o t h to w i t h i n 0 . 0 2 mm a n d w i t h i n 0 . 0 0 1 r a d i a n s of p e r p e n d i c u l a r i t y to t h e s a m p l e a x i s . 4 ) F o u r s t r a i n g a u g e s w e r e g l u e d to t h e s a m p l e s , t w o i n t h e d i a m e t r a l a n d t w o i n t h e a x i a l o r i e n t a t i o n , a n d a l l o w e d to c u r e f o r 48 h o u r s . 71 4 . 4 . 3 T e s t P r o c e d u r e s T h e t e s t p r o c e d u r e s e m p l o y e d f o r t h e u n i a x i a l c o m p r e s s i v e t e s t s a m p l e s c o n f o r m e d to g e n e r a l a c c e p t e d p r a c t i s e . A l l s a m p l e s w e r e t e s t e d i n t h e d r y c o n d i t i o n . T h e s a m p l e s w e r e a l l l o a d e d o n a t e s t m a c h i n e w i t h a 2700 K i l o N e w t o n c a p a c i t y l o a d f r a m e . A s e t o f p l a t e n s c o m p r i s i n g a s p h e r i c a l s e a t w a s p l a c e d u n d e r t h e s a m p l e a n d a s i n g l e p l a t e n w a s p l a c e d o v e r t h e s a m p l e . A l i n e a r v o l t a g e d i f f e r e n t i a l t r a n s d u c e r w a s t h e n c l a m p e d i n t o p l a c e b e t w e e n t h e u p p e r l o a d i n g p l a t e n s a n d t h e f r a m e of t h e m a c h i n e a n d w a s o r i e n t e d p a r a l l e l t o t h e l o a d i n g a x i s . T h e l o a d o n t h e s a m p l e s w a s c y c l e d two to t h r e e t i m e s to 10% o f t h e a n t i c i p a t e d l o a d c a r r y i n g c a p a c i t y o f t h e s a m p l e . T h e l o a d w a s t h e n i n c r e a s e d to f a i l u r e a t a r a t e o f a p p r o x i m a t e l y 80 p o u n d s p e r s e c o n d . D u r i n g t h e l o a d i n g s e q u e n c e , t h e l o a d w a s m o n i t o r e d w i t h a H o t t i n g e r B a l d w i n M e a s u r e m e n t s , T y p e C I O , P r e s s u r e c e l l c o u p l e d to a D a y t r o n i c M o d e l 3270P S t r a i n I n d i c a t o r . T h e l i n e a r v o l t a g e d i f f e r e n t i a l t r a n s d u c e r w a s c o u p l e d w i t h a T r a n s t e k M o d e l 1002 t r a n s d u c e r i n d i c a t o r , a n d t h e s t r a i n g a u g e s w e r e m o n i t o r e d w i t h a V i s h a y E l l i s r e c o r d e r u s i n g a o n e - q u a r t e r b r i d g e r e s i s t a n c e b a l a n c e . 72 A . 4 . 4 R e s u l t s T h e r e s u l t a n t s t r e s s - s t r a i n c u r v e s f r o m t h e L V D T d a t a a n d t h e s t r a i n g a u g e s a r e g i v e n i n A p p e n d i c e s X a n d X I . T h e c a l c u l a t e d r e s u l t s a r e g i v e n i n T a b l e 4 . 7 . T a b l e 4 . 8 p r e s e n t s t h e c a l c u l a t e d a v e r a g e v a l u e s a g a i n s t t h e f o l i a t i o n a n g l e . T a b l e 4 . 7 U n i a x i a l C o m p r e s s i v e T e s t R e s u l t s S a m p l e N o . F o l i a t i o n A n g l e U c s ( M P a ) E ( M P a ) ( x l 0 3 ) V L V D T S T R . G A U 1 8 0 ° 1 1 5 . 6 2 2 7 . 5 9 1 . 9 0 . 1 5 2 8 0 ° 9 0 . 4 5 2 3 . 8 7 2 . 6 0 . 1 5 3 0 ° - 5 ° 1 8 7 . 9 7 2 9 . 6 7 6 . 9 0 . 1 9 4 8 0 ° 1 4 8 . 6 5 2 8 . 0 105 .0 ** 5 4 5 ° - 5 0 ° 1 1 9 . 3 0 2 6 . 5 7 1 . 0 0 . 1 9 6 5o 1 5 9 . 9 3 - 5 6 . 6 0 . 1 6 7 1 5 ° 1 5 2 . 2 7 - 8 2 . 8 0 . 2 0 * * R e a d i n g s f r o m a x i a l s t r a i n g a u g e s u s p e c t 73 T a b l e 4 . 8 A n i s o t r o p i c V a r i a t i o n i n R o c k C h a r a c t e r i s t i c s F o l i a t i o n U c s E A n g l e ( l ) ( M P a ) S T R ( M P a x l O 4 ) 0 ° - 4 4 ° 1 6 6 . 7 2 7 . 2 1 0 . 1 8 4 5 ° _ 9 0 ° 1 1 8 . 5 0 7 . 8 5 0 . 1 6 A l l s a m p l e s 1 3 9 . 1 7 7 . 5 3 0 . 1 7 (1 ) T o c o r e a x i s 4 . 4 . 5 D i s c u s s i o n A s c a n b e s e e n f r o m T a b l e 4 . 7 t h e v a l u e s of Y o u n g ' s M o d u l u s o b t a i n e d f r o m t h e l i n e a r v o l t a g e d i f f e r e n t i a l t r a n s d u c e r a n d t h e s t r a i n g a u g e s a r e m a r k e d l y d i f f e r e n t . In a d d i t i o n a l t e s t i n g w i t h t h e e q u i p m e n t u s e d i n t h e u n i a x i a l c o m p r e s s i v e t e s t s , i t w a s f o u n d t h a t t h e L V D T w a s no t p r o p e r l y m o u n t e d i n t h e a p p a r a t u s . A s a r e s u l t , t h e d e f o r m a t i o n i n t h e l o a d c e l l i s n o t t a k e n i n t o a c c o u n t a n d t h e c a l c u l a t e d m o d u l i f r o m t h e L V D T r e a d i n g s a r e i n e r r o r . C a l i b r a t i o n of t h e l o a d c e l l d e f o r m a t i o n i n d i c a t e s t h a t t h e s e v a l u e s s h o u l d b e m u l t i p l i e d b y a c o r r e c t i o n 74 f a c t o r of a p p r o x i m a t e l y 2 . 8 . A l l f u r t h e r d i s c u s s i o n i s t h e r e f o r e b a s e d u p o n t h e r e s u l t s o b t a i n e d f r o m t h e s t r a i n g a u g e s . T h e c a l c u l a t e d a v e r a g e v a l u e s o f t h e 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 , Y o u n g ' s M o d u l u s a n d P o i s s o n ' s R a t i o c l e a r l y i n d i c a t e t h e a n i s o t r o p i c b e h a v i o u r of t h e f o l i a t e d a n d e s i t i c r o c k s . T h e m o s t f a v o u r a b l e o r i e n t a t i o n o f t h e f o l i a t i o n f o r t h e s e r o c k s w o u l d b e s u b - p e r p e n d i c u l a r to t h e o p e n i n g s i n t h e p i l l a r s a n d a b u t m e n t s a n d s u b - p a r a l l e l to t h e o p e n i n g s i n t h e w a l l s o f t h e s t o p e s . F o r d e s i g n p u r p o s e s , t h e l o w e r v a l u e s , w i t h a f o l i a t i o n a n g l e a t 4 5 ° - 9 0 ° to t h e d i r e c t i o n o f l o a d i n g , s h o u l d b e u s e d . T a b l e 4 . 9 S u m m a r y of D e s i g n V a l u e s L i t h o l o g i c a l U n i t s U c s ( M P a ) E ( M P a x l O 3 ) T u f f s e d i m e n t a r y 9 2 . 8 3 7 3 . 0 0 . 2 9 C h l o r i t i z e d A m p h . 5 0 . 4 5 1 7 . 4 0 . 2 0 A n d e s i t e C h l o r i t i z e d A n d e s i t e 9 9 . 2 9 7 3 . 9 0 . 1 6 75 4 . 5 T R I A X I A L T E S T S 4 . 5 . 1 G e n e r a l T r i a x i a l t e s t s w e r e c o m p l e t e d o n 11 s a m p l e s o f c h l o r i t i z e d a n d e s i t e o b t a i n e d f r o m t h e l a r g e s a m p l e b l o c k s o n t h e S e c o n d L e v e l . T h e s e s a m p l e s w e r e p r e p a r e d b y t h e m e t h o d s d e s c r i b e d f o r t h e u n i a x i a l c o m p r e s s i v e t e s t s . 4 . 5 . 2 T e s t P r o c e d u r e s F o r t h e t r i a x i a l c o m p r e s s i v e t e s t s , a H o e k c e l l w a s e m p l o y e d to a p p l y t h e d e s i r e d c o n f i n i n g s t r e s s . F o r e a c h t e s t t h e p r e p a r e d s a m p l e w a s f i r s t p l a c e d i n t h e H o e k c e l l s o t h a t e a c h e n d p r o t r u d e d a m i n i m u m o f 5 m m , t h u s a l l o w i n g r o o m b e t w e e n t h e c e l l a n d t h e l o a d i n g p l a t e n s f o r a x i a l d e f o r m a t i o n . A f t e r p o s i t i o n i n g t h e s a m p l e t h e h y d r a u l i c p r e s s u r e i n t h e c e l l w a s i n c r e a s e d to t h e d e s i r e d c o n f i n i n g s t r e s s a n d t h e c e l l a n d s a m p l e w e r e c e n t e r e d i n t h e t e s t i n g m a c h i n e . T h e r e m a i n d e r of t h e l o a d i n g p r o c e d u r e w a s i d e n t i c a l to t h a t u s e d i n t h e u n i a x i a l c o m p r e s s i v e t e s t s . D u r i n g t h e l o a d i n g s e q u e n c e , a x i a l d e f o r m a t i o n w a s m o n i t o r e d w i t h a l i n e a r v o l t a g e d i f f e r e n t i a l t r a n s d u c e r c o u p l e d w i t h a T r a n s t e k M o d e l 1002 t r a n s d u c e r i n d i c a t o r . 76 4 . 5 . 3 R e s u l t s S t r e s s - s t r a i n d a t a was o b t a i n e d f r o m t e n of t h e e l e v e n t r i a x i a l t e s t s . T h e r e s u l t i n g c u r v e s a r e g i v e n i n A p p e n d i x X I I . T h e r e s u l t s of t h e t e s t s a r e s u m m a r i z e d i n T a b l e 4 . 1 0 . T a b l e 4 . 1 0 S u m m a r y of T r i a x i a l T e s t R e s u l t s S a m p l e F o l i a t i o n C o n f i n i n g C r i t i c a l A v . C r i t . N o . A n g l e S t r e s s S t r e s s S t r e s s °3 ° 1 ( ° ) ( M P a ) ( M P a ) ( M P a ) 1 85 6 . 9 0 1 1 3 . 5 7 1 6 3 . 4 8 4 75 6 . 9 0 2 1 3 . 3 8 3 85 1 0 . 3 4 2 1 1 . 1 3 2 1 1 . 1 3 2 85 1 3 . 7 9 2 6 2 . 0 2 6 20 1 3 . 7 9 1 2 6 . 4 5 2 1 8 . 8 5 7 40 1 3 . 7 9 2 0 7 . 8 5 8 5 1 3 . 7 9 2 3 2 . 0 5 5 45 1 7 . 4 6 2 5 7 . 6 0 2 5 7 . 6 0 9 45 2 0 . 6 9 2 3 7 . 6 0 10 45 2 0 . 6 9 1 8 9 . 6 1 2 2 8 . 7 6 11 35 2 0 . 6 9 2 1 9 . 9 2 77 4 . 5 . 4 D i s c u s s i o n A s c a n b e s e e n f r o m T a b l e 4 . 1 0 , t h e r e s u l t s v a r y s u b s t a n t i a l l y f r o m s a m p l e to s a m p l e . T h u s , i n o r d e r to a n a l y s e t h e r e s u l t s , t h e c r i t i c a l s t r e s s v a l u e s w e r e a v e r a g e d f o r e a c h l e v e l o f c o n f i n i n g s t r e s s . T h e r e s u l t s f r o m s a m p l e s 6 a n d 10 w e r e i g n o r e d b e c a u s e t h e s e t w o s a m p l e s f a i l e d d i r e c t l y a l o n g w e a k f o l i a t i o n p l a n e s . A s i n t h e u n i a x i a l c o m p r e s s i v e t e s t s , t h e r e a p p e a r s to b e a v a r i a t i o n i n s t r e n g t h w i t h t h e o r i e n t a t i o n o f t h e f o l i a t i o n w i t h r e s p e c t to t h e c r i t i c a l a p p l i e d s t r e s s . T h u s , t h e r e s u l t s f r o m S a m p l e s 2 a n d 5 w e r e a l s o i g n o r e d . F i g u r e 4 . 9 s h o w s t h e M o h r ' s c i r c l e s f o r t h e r e m a i n d e r of t h e t r i a x i a l t e s t s o n t h e c h l o r i t i z e d a n d e s i t e . T h i s i n t e r p r e t a t i o n a l s o i n c l u d e s t h e r e s u l t s o f t h e u n i a x i a l c o m p r e s s i v e t e s t s ( c o n f i n i n g s t r e s s = 0) f r o m s a m p l e s w i t h f o l i a t i o n a t 4 5 ° - 9 0 ° to t h e c o r e a x i s ( U c s = 1 1 8 . 5 0 M P a ) . It i s e s t i m a t e d t h a t t h e i n t e r n a l a n g l e o f f r i c t i o n o f t h e i n t a c t r o c k r a n g e s f r o m 5 5 ° to 2 1 ° b e t w e e n z e r o c o n f i n e m e n t a n d a c o n f i n i n g s t r e s s of 2 0 . 6 9 M P a . T h e c o h e s i o n i s e s t i m a t e d a t 11 M P a w h e n t h e m a j o r 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 a t 4 0 ° to 9 0 ° to t h e f o l i a t i o n . A s t h e o r i e n t a t i o n a n g l e d e c r e a s e s b e l o w 4 5 ° , t h e i n t e r n a l a n g l e of f r i c t i o n a n d c o h e s i o n a r e l i k e l y to i n c r e a s e . 78 F i g u r e 4.9 M o h r ' s c i r c l e s f r o m T r i a x i a l T e s t D a t a . 79 4 . 6 S P E C I F I C G R A V I T Y T E S T S S p e c i f i c g r a v i t y t e s t s a r e r e q u i r e d to e s t i m a t e t h e v e r t i c a l s t r e s s f o r t h e i n i t i a l n u m e r i c a l m o d e l l i n g p r o g r a m a n d to v e r i f y t h e r e s u l t s o f i n - s i t u s t r e s s m e a s u r e m e n t s . In a d d i t i o n , t h e s p e c i f i c g r a v i t y t e s t r e s u l t s a r e r e q u i r e d to c a l c u l a t e t o n n a g e f a c t o r s f o r m i n e p l a n n i n g p u r p o s e s . 4 . 6 . 1 P r e v i o u s w o r k T h e M c L e l l a n s i t e s t a f f h a v e c o m p l e t e d s p e c i f i c g r a v i t y t e s t s o n f o u r c o m p o s i t e s a m p l e s o f o r e z o n e m a t e r i a l . T h e r e s u l t s of t h e s e t e s t s a r e s u m m a r i z e d i n T a b l e 4 . 1 1 . T a b l e 4 . 1 1 S p e c i f i c G r a v i t y o f O r e Z o n e M a t e r i a l S A M P L E N O . S P E C I F I C G R A V I T Y C o m p o s i t e 111 3 . 1 7 +_ 0 . 3 0 C o m p o s i t e //3 3 . 4 1 _+ 0 . 0 6 C o m p o s i t e lib 3 . 4 7 +_ 0 . 0 7 C o m p o s i t e 1/6 3 . 4 7 _+ 0 . 0 7 M e a n 3 . 3 8 +_ 0 . 2 0 80 A . 6 . 2 S a m p l e P r e p a r a t i o n B e f o r e t e s t i n g t h e s a m p l e s , a l l s a m p l e s w e r e w a s h e d to r e m o v e l o o s e p a r t i c l e s . T h e s a m p l e s w e r e t h e n s o a k e d f o r 48 h o u r s to f u l l y s a t u r a t e t h e m . I m m e d i a t e l y p r i o r to t e s t i n g , e a c h s a m p l e w a s s u r f a c e d r i e d w i t h p a p e r t o w e l s . 4 . 6 . 3 T e s t P r o c e d u r e s T h e p r o c e d u r e u s e d i n o b t a i n i n g t h e s p e c i f i c g r a v i t y o f e a c h s a m p l e w a s a s f o l l o w s : 1 . A g l a s s b e a k e r w a s f i l l e d t o t h e t o p w i t h w a t e r a t 2 2 ° C . 2 . T h e w e i g h t o f t h e w a t e r a n d b e a k e r (W^) w a s o b t a i n e d to t h e n e a r e s t g r a m . 3 . T h e s u r f a c e d r i e d s a m p l e w a s w e i g h e d to t h e n e a r e s t g r a m (W2K 4 . T h e s a m p l e w a s s l o w l y l o w e r e d i n t o t h e b e a k e r , a l l o w i n g t h e e x c e s s w a t e r t o r u n o u t . 5 . T h e o u t s i d e o f t h e b e a k e r w a s d r i e d w i t h p a p e r t o w e l s . 6 . T h e w e i g h t o f t h e r e m a i n i n g w a t e r , t h e s a m p l e a n d t h e b e a k e r (W3) w a s r e c o r d e d . T h e s p e c i f i c g r a v i t y w a s t h e n c a l c u l a t e d a s f o l l o w s : 81 1 . V o l u m e o f s a m p l e = V o l u m e o f w a t e r d i s p l a c e d . V s = V w S G W W h e r e V s = v o l u m e o f s a m p l e V w = v o l u m e o f w a t e r d i s p l a c e d S G W = s p e c i f i c g r a v i t y o f w a t e r a t 2 2 ° C = 1 g m / c c 2 . M a s s o f s a m p l e = W2« 3 . S . G . o f s a m p l e = W 2 / V g . 4 . 6 . 4 R e s u l t s T h e r e s u l t s o f t h e t e s t s a r e g i v e n i n A p p e n d i x X I I I , a n d a r e s u m m a r i z e d i n T a b l e 4 . 1 2 . 82 T a b l e 4 . 1 2 S p e c i f i c G r a v i t y of H o s t R o c k s S a m p l e D r i l l H o l e L o c a t i o n L i t h o l o g i c a l S . G . S . G . N o . N o . (m) U n i t ( g m / c c ) ( a v e ) ( g m / c c ) 1 U 8 2 - 5 2 4 9 . 3 3 T u f f . S e d . 2 .81 2 U 8 2 - 5 188 .67 II 2 . 8 7 3 U 8 2 - 4 1 9 2 . 0 2 II 2 . 8 3 4 A S 8 4 - 5 0 4 3 . 8 9 II 3 . 0 2 5 U 8 2 - 3 1 3 7 . 4 6 II 2 . 9 5 2 . 9 0 6 ? ? A m p h . A n d 2 . 9 7 7 U 8 2 - 2 6 4 . 1 8 II 3 . 0 7 8 U 8 2 - 5 1 5 . 5 4 II 2 . 9 6 9 U 8 2 - 6 7 5 . 9 0 n 3 . 1 1 10 U 8 2 - 5 2 8 8 . 8 5 C h l o r . A n d 3 . 1 3 11 U 8 2 - 4 9 7 . 5 4 ti 3 . 0 7 12 U 8 2 - 6 3 9 . 3 2 II 2 . 8 7 13 A U 8 4 - 3 4 5 1 . 0 0 M 2 . 9 6 14 U 8 2 - 1 1 7 5 . 5 6 II 3 . 1 2 3 . 0 3 15 U 8 2 - 6 3 0 . 4 8 A n d e s i t e 2 . 9 3 16 U 8 2 - 3 1 8 . 2 8 II 2 . 7 8 17 A S 8 3 - 1 7 1 1 3 . 3 9 II 3 . 1 0 18 A U 8 5 - 1 5 2 7 . 4 4 II 2 . 8 9 19 U 8 2 - 5 1 7 9 . 8 3 II 2 . 8 9 2 . 9 2 O V E R A L L A V E R A G E 2 . 9 6 83 4.6.5 D i s c u s s i o n T h e i n d i v i d u a l v a l u e s o b t a i n e d f o r t h e s p e c i f i c g r a v i t y of t h e s a m p l e s a r e a c c u r a t e to w i t h i n +5%. V a r i a t i o n i n t h e s p e c i f i c g r a v i t y of e a c h l i t h o l o g i c a l u n i t a r e d u e p r i m a r i l y to t h e d i f f e r e n c e i n t h e m i n e r a l o g i c a l c o m p o s i t i o n b e t w e e n t h e s a m p l e s . A m o r e r i g o r o u s t e s t i n g p r o g r a m w o u l d l i k e l y h a v e l i t t l e e f f e c t o n t h e m e a n s p e c i f i c g r a v i t y o f e a c h l i t h o l o g i c a l u n i t i n t h e h o s t r o c k s . F o r n u m e r i c a l m o d e l l i n g p u r p o s e s , t h e p r e s e n t d a t a i s s u f f i c i e n t . 84 4 . 7 C O N C L U S I O N S T h e r o c k m a s s at t h e M c L e l l a n M i n e c o n s i s t s p r e d o m i n a n t l y of r e l a t i v e l y h a r d , c o m p e t e n t c h l o r i t i z e d a n d e s i t e a n d t u f f a c e o u s s e d i m e n t s . T h e r o c k m a s s r a t i n g of t h e s e r o c k s v a r i e s c o n s i d e r a b l y w i t h e l e v a t i o n a n d f r o m d o m a i n to d o m a i n . It i s c o n c l u d e d t h a t b e t w e e n e l e v a t i o n 1160 m a n d 1400 m : 1) T h e r o c k m a s s r a t i n g o f t h e H a n g i n g w a l l D o m a i n i s 75% w i t h i n t h e a r e a of i n f l u e n c e of t h e u n d e r g r o u n d e x c a v a t i o n . 2 ) W h e r e t h e h a n g i n g w a l l s of t h e s t o p e s a r e w i t h i n t h e H a n g i n g w a l l D o m a i n , d i l u t i o n f r o m t h e w a l l s w i l l b e m i n i m a l . 3 ) If c o n t r o l l e d b l a s t i n g t e c h n i q u e s a r e e m p l o y e d , t h e d i l u t i o n f r o m t h e s e w a l l s w i l l b e i n t h e o r d e r of 5%. 4 ) W i t h i n t h e N o r t h S h e a r , t h e r o c k m a s s r a t i n g r a n g e s f r o m 45% to 50%. 5) A p p r o x i m a t e l y 50% of t h e h a n g i n g w a l l s o f t h e s t o p e s w i l l b e w i t h i n o r a d j a c e n t to t h e N o r t h S h e a r . 6 ) W h e r e t h e h a n g i n g w a l l s of t h e s t o p e s a r e w i t h i n o r a d j a c e n t to t h e N o r t h S h e a r , d i l u t i o n i s a n t i c i p a t e d to i n c r e a s e to 15% to 20%. 7 ) W i t h t h e u s e of c o n t r o l l e d b l a s t i n g t e c h n i q u e s a n d t h e i n s t a l l a t i o n of s u p p o r t i m m e d i a t e l y a f t e r e a c h b l a s t , t h e d i l u t i o n w i l l l i k e l y b e i n t h e o r d e r o f 5% to 10%. 85 8 ) T h e r o c k m a s s r a t i n g of t h e F o o t w a l l D o m a i n i s g e n e r a l l y i n t h e o r d e r of 70% to 75% w i t h i n t h e a r e a o f i n f l u e n c e o f t h e u n d e r g r o u n d e x c a v a t i o n s . I s o l a t e d a r e a s o f l i m i t e d e x t e n t h a v e r o c k m a s s r a t i n g s i n t h e o r d e r o f 60%. 9 ) D i l u t i o n i s e x p e c t e d to b e o f t h e o r d e r o f 5% w h e r e t h e r o c k m a s s r a t i n g i s i n t h e 70% to 75% r a n g e a n d o f t h e o r d e r of 10% to 15% w h e r e t h e r o c k m a s s r a t i n g i s i n t h e o r d e r of 60%. 10) T h e r o o f o f e a c h c u t w i l l l i k e l y s t a n d u n s u p p o r t e d w h e r e t h e r o c k m a s s r a t i n g i s 75% o r h i g h e r a n d t h e w i d t h o f t h e c u t d o e s no t e x c e e d 20 m e t r e s . 11) W h e r e t h e r o c k m a s s r a t i n g i s l e s s t h a n 75% a n d / o r t h e w i d t h of t h e c u t e x c e e d s 20 m e t r e s t h e i n s t a l l a t i o n o f t e m p o r a r y s u p p o r t may b e r e q u i r e d . 12) F o r d e s i g n p u r p o s e s t h e m a t e r i a l c o n s t a n t s o f t h e r o c k m a s s a r e e s t i m a t e d to b e m= 1 0 , s = 0 . 0 5 b e l o w e l e v a t i o n 1400 m a n d m = 7 . 5 , s = 0 .1 a b o v e e l e v a t i o n 1400 m . 13) In t h e N o r t h S h e a r t h e r e s p e c t i v e v a l u e s a r e e s t i m a t e d a t 0 . 5 0 a n d 0 . 0 0 0 1 . H o w e v e r , d u e to t h e l i m i t e d t h i c k n e s s o f t h e N o r t h S h e a r i t i s no t e x p e c t e d to h a v e a s i g n i f i c a n t b e a r i n g o n t h e o v e r a l l p i l l a r d e s i g n . 14) T h e i n - s i t u d e f o r m a t i o n m o d u l u s of t h e r o c k s i s e s t i m a t e d at 50 G P a b e l o w 1400 m a n d 10 G P a a b o v e 1400 m . 15) T h e r e s u l t s o f t h e l a b o r a t o r y t e s t i n g p r o g r a m w i l l p r o v i d e a d e q u a t e d a t a f o r n u m e r i c a l m o d e l l i n g . B a s e d u p o n t h e r o c k m a s s r a t i n g s , d e s i g n v a l u e s h a v e b e e n a s s i g n e d a s s u m m a r i z e d i n T a b l e 4 . 1 3 . A b o v e e l e v a t i o n 1400 m ( i n t h e w e a t h e r e d r o c k ) a m o d u l u s of 10 G P a s h o u l d b e u s e d f o r a l l r o c k t y p e s . T a b l e 4 . 1 3 D e s i g n V a l u e s f o r N u m e r i c a l M o d e l l i n g D o m a i n L i t h U n i t U c s ( M P a ) E ( G P a ) ( D e g ) C ( M P a ) S . G . H a n g i n g w a l l N o r t h S h e a r F o o t w a l l F o o t w a l l A l l A l l T S C A 95 50 92 100 50 10 50 50 0 . 2 0 0 . 1 7 0 . 2 9 0 .17 55 11 2 . 9 8 3 . 0 2 2 . 9 0 3 . 0 3 C H A P T E R 5 E S T I M A T I O N O F I N - S I T U S T R E S S E S 88 5 .0 I N T R O D U C T I O N In A u g u s t , 1985 i n - s i t u s t r e s s m e a s u r e m e n t s w e r e c o m p l e t e d a t t h e M c L e l l a n M i n e u s i n g C S I R O H o l l o w I n c l u s i o n S t r a i n c e l l s i n c o n j u n c t i o n w i t h a n o v e r c o r i n g t e c h n i q u e . T h e s e m e a s u r e m e n t s w e r e c o n d u c t e d u n d e r t h e A g a s s i z R o c k M e c h a n i c s R e s e a r c h G r a n t to o b t a i n r e l i a b l e e s t i m a t e s of t h e i n - s i t u s t r e s s c o n d i t i o n s a t t h e s i t e a n d p r o v i d e i n p u t d a t a f o r n u m e r i c a l m o d e l l i n g of t h e p r o p o s e d c u t - a n d - f i l l s t o p e s . T h e o n - s i t e w o r k w a s c o n d u c t e d b y p e r s o n n e l f r o m t h e D e p a r t m e n t of M i n i n g a n d M i n e r a l P r o c e s s E n g i n e e r i n g at U . B . C . w i t h t h e a s s i s t a n c e o f o n - s i t e s t a f f o f S h e r r i t t G o r d o n M i n e s L t d . T h i s c h a p t e r p r e s e n t s t h e e q u i p m e n t a n d t e s t p r o c e d u r e s u s e d at t h e M c L e l l a n M i n e . T h e r e s u l t s of t h e s t r e s s m e a s u r e m e n t p r o g r a m a r e p r e s e n t e d a n d t h e i r r e l i a b i l i t y a n d c o n s i s t e n c y w i t h o t h e r s t r e s s m e a s u r e m e n t w o r k i s d i s c u s s e d . In a d d i t i o n , t h e r e s u l t s a r e e x a m i n e d w i t h r e s p e c t to t h e r e g i o n a l a n d s i t e s t r u c t u r a l g e o l o g y . F o r a t h e o r e t i c a l a n a l y s i s of t h e u s e of t h e C S I R O H o l l o w I n c l u s i o n S t r a i n c e l l t h e r e a d e r i s r e f e r r e d to W o r o t n i c k i , 1 9 7 6 7 0 . 89 5.1 STRESS MEASUREMENT EQUIPMENT 5.1.1 CSIRO Hollow Inclusion Cell System The CSIRO Hollow Cell System consists of three basic components. The main component, the H.I. cell, consists of an array of nine strain gauges (Figure 5.1) fully encapsulated in a resin cylinder.^ In addition, a tenth circuit is incorporated into the cell through a thin copper wire across the back end of the cell. This circuit provides a continuity check which is broken when all of the glue is extruded. These ten circuits are completed through a twelve wire cable leading to the collar of the drill hole. The junction of the cable and the cell is also fully encapsulated in resin to provide a water-proof seal. Two screws on the outside of the back end of the cell provide a means for orienting the cell. The second component of the CSIRO H.I. Cell System is an epoxy piston. This piston is used to extrude the glue from the cell, back through the hollow core and radial holes through the end of the piston. After the grout is poured into the cell, the 9 0 I 1 J 1 j C | I A \ \ B> I l I I V O r i e n t a t i o n o f S t r a i n Gauge R o -s e t t e s a r o u n d t h e b o d y o f t h e s h e l l "4, r~ Iii Lc_: lO - C e n t e r i n g T i p D e p t h L o c a t i n g R o d Lubber S e a l s -Cement E x i t H o l e s P i s t o n Shear P i n s (4) X e n t e r i n g L u g s - M a i n b o d y w i t h ' h r e e S t r a i n Gauge R o s e t t e s ' r i p w i r e a c r o s s body o f _ C e n t e r i n g L u g s Gauge R u b b e r S e a l s O r i e n t i n g P i n s ( 2 ) ( P u l l W i r e f o r P u l l T y p e ) 12 C o r e C a b l e V F i g u r e 5 .1 - H o l l o w I n c l u s i o n C e l l a n d I n s t a l l a t i o n C o m p o n e n t s 91 p i s t o n i s i n s e r t e d i n t o t h e c e l l a n d f i x e d i n p l a c e b y l e a d s h e a r p i n s i n e a c h of t h e f o u r h o l e s w h i c h l i n e u p t h r o u g h t h e w a l l o f t h e c e l l i n t o t h e p i s t o n . T h e t h i r d c o m p o n e n t of t h e s y s t e m i s a w o o d e n r o d w h i c h i s i n s e r t e d i n t h e f r o n t e n d of t h e p i s t o n . W h e n t h i s w o o d e n r o d i s c u t to t h e d e s i r e d l e n g t h i t a c t s a s a " d e p t h l o c a t i n g d e v i c e " t o e n s u r e p r o p e r p l a c e m e n t of t h e c e l l . 5 . 1 . 2 D a t a R e c o r d i n g S y s t e m In a d d i t i o n to t h e s e c o m p o n e n t s , a d a t a l o g g i n g o r i n s t r u m e n t a t i o n m e a s u r e m e n t d e v i c e i s r e q u i r e d to m o n i t o r t h e i n d u c e d s t r a i n d u r i n g t h e o v e r c o r i n g p r o c e d u r e . A t t h e M c L e l l a n M i n e , i t w a s o r i g i n a l l y p l a n n e d to u s e a F L U K E 2280A d a t a l o g g e r w i t h a t a p e d r i v e . H o w e v e r , w h i l e m o n i t o r i n g t h e s t r a i n s i n d u c e d b y t h e t e m p e r a t u r e c h a n g e s d u r i n g t h e s e t t i n g of t h e g l u e i n t h e f i r s t s t r a i n c e l l , t h e d a t a l o g g e r s t o p p e d f u n c t i o n i n g . A l o n g d e l a y w o u l d h a v e b e e n i n c u r r e d i f t h e d a t a l o g g e r w a s to b e f i x e d o r r e p l a c e d . T h u s , a V i s h a y S t r a i n R e c o r d e r a n d B a l a n c e U n i t w e r e o b t a i n e d f r o m I n c o at T h o m p s o n , M B . T h i s s y s t e m w a s u s e d to o b t a i n a l l o f t h e s t r e s s m e a s u r e m e n t d a t a . 92 5 . 1 . 3 B i a x i a l T e s t E q u i p m e n t T o o b t a i n t h e e l a s t i c c o n s t a n t s of t h e r o c k - c e l l o v e r c o r e c o m p o s i t e a b i a x i a l c e l l , w h i c h w a s c o n s t r u c t e d at t h e D e p a r t m e n t of M i n i n g a n d M i n e r a l P r o c e s s E n g i n e e r i n g a t U . B . C . , w a s u s e d i n c o n j u n c t i o n w i t h a h a n d h y d r a u l i c p u m p . 93 5.2 M E T H O D O L O G Y T h e o v e r c o r i n g t e c h n i q u e u s e d at t h e M c L e l l a n M i n e to m e a s u r e t h e i n - s i t u s t r e s s e s b a s i c a l l y i n v o l v e s f i v e s t e p s ( F i g u r e 5.2). F i r s t a l a r g e d i a m e t e r h o l e ( H X ) i s d r i l l e d to t h e t a r g e t d e p t h . T h e n a n E X p i l o t h o l e i s d r i l l e d t w o f ee t a h e a d o f t h e H X h o l e a n d a s i t e i s s e l e c t e d f o r t h e i n s t a l l a t i o n of t h e H . I . c e l l . T h e c e l l i s t h e n g r o u t e d i n t o p l a c e w i t h a r e s i n g r o u t . A f t e r t h e g r o u t h a s b e e n a l l o w e d to c u r e , t h e H . I . c e l l i s o v e r c o r e d w i t h a n H X d i a m o n d b i t a n d t h e s t r a i n r e l e a s e i s m o n i t o r e d . T h e H . I . c e l l - o v e r c o r e c o m p o s i t e i s t h e n r e t r i e v e d a n d a b i a x i a l t e s t o n t h e c o m p o s i t e i s c o m p l e t e d . T h e two m o s t c r i t i c a l a s p e c t s o f t h i s p r o c e d u r e a r e t e c h n i c a l l y t h e l e a s t c o n t r o l l a b l e . T h e a c t u a l p r o c e s s of g r o u t i n g t h e c e l l i n p l a c e i s p r o b a b l y t h e m o s t c r i t i c a l s t e p . T o e n s u r e p r o p e r g r o u t i n g of t h e H . I . c e l l to t h e w a l l s of t h e h o l e t h e f o l l o w i n g p r e c a u t i o n s w e r e t a k e n : 1) T h e r e s i n a n d h a r d e n e r w e r e o r d e r e d s p e c i f i c a l l y f o r t h e t e m p e r a t u r e of t h e r o c k a t t h e s i t e . 2) A s t h e a i r t e m p e r a t u r e i n t h e m i n e w a s b e l o w 1 5 ° C , t h e 94 D r i l l 150mm d i a . h o l e to n e a r t a r g e t d e p t h \ r - = C M i n . 1.5xdiameter o f d e v e l o p m e n t D r i l l ex h o l e a b o u t 600mm . Inspect c o r e f o r b e s t L — r- X s i t e f o r H . I . C e l l J o i n t I n s t a l l H . I . C e l l , a l l o w g r o u t t o c u r e l _ ^ O v e r c o r e H . I . C e l l . M o n i t o r s t r a i n gauge t h r o u g h o u t B r e a k o f f c o r e , r e t r i e v e H . I . C e l l a n d r o c k a n n u l u s 1 V»* F i g u r e 5 . 2 - P r o c e d u r e f o r I n s t a l l a t i o n a n d O v e r c o r i n g O v e r c o r i n g of H o l l o w I n c l u s i o n S t r a i n C e l l 95 r e s i n a n d h a r d e n e r w e r e s t o r e d a n d m i x e d i n a w a r m p l a c e to e n s u r e c o m p l e t e m i x i n g , a m i n i m u m o f e n t r a i n e d a i r a n d p r o p e r e x t r u s i o n of t h e g l u e d u r i n g i n s t a l l a t i o n . 3 ) W h e n t h e g r o u t w a s p o u r e d i n t o t h e H . I . c e l l i t w a s p o u r e d i n a t h i n s t r e a m d o w n t h e s i d e o f t h e c e l l to a l l o w e n t r a i n e d a i r to e s c a p e . A ) B e f o r e t h e g r o u t w a s e x t r u d e d t h e c e l l was o r i e n t e d a p p r o x i m a t e l y 9 0 ° f r o m t h e d e s i r e d o r i e n t a t i o n . A f t e r t h e g r o u t w a s e x t r u d e d t h e c e l l w a s t u r n e d to i t s f i n a l p o s i t i o n , t h u s f o r c i n g t h e g r o u t i n t o c r a c k s a n d p i t s i n t h e w a l l o f t h e h o l e . 5 ) W h e n t h e g r o u t w a s e x t r u d e d t h e i n s t a l l a t i o n r o d s w e r e p u s h e d i n s l o w l y w i t h f i r m , e v e n , p r e s s u r e u n t i l t h e c o n t i n u i t y a c r o s s t h e c o p p e r s h e a r w i r e w a s b r o k e n . T h e s e c o n d m o s t c r i t i c a l a s p e c t of t h e w h o l e p r o c e d u r e i s t h e o v e r c o r i n g i t s e l f . I d e a l l y a d r i l l i n g m a c h i n e w i t h h y d r a u l i c f e e d , a c h u c k s p e e d r a n g i n g d o w n to 120 r . p . m . a n d a p e n e t r a t i o n r a t e of 1-2 c m p e r m i n u t e i s p r e f e r r e d . D u r i n g t h e a c t u a l o v e r c o r i n g , t h e b i t p r e s s u r e a n d p e n e t r a t i o n r a t e s h o u l d b e c o n s t a n t . 96 In a d d i t i o n , d u r i n g t h e o v e r c o r i n g p r o c e s s t h e d r i l l e r ' s h e l p e r s h o u l d a p p l y a p p r o x i m a t e l y t e n p o u n d s of t e n s i o n to t h e H . I . c e l l c a b l e to e n s u r e t h a t t h e c a b l e d o e s no t g e t p i n c h e d o r c u t b y t h e d r i l l r o d s . If t h i s t e n s i o n v a r i e s c o n s i d e r a b l y a n d t h e s t r e s s r e l i e f o f t h e o v e r c o r e i s s m a l l , t h e m e a s u r e m e n t s may b e too e r r a t i c to i n t e r p r e t . T h e t e n s i l e s t r a i n s i n d u c e d i n t h e c a b l e a n d c e l l b y t h i s t e n s i o n m a y m a s k t h e s t r a i n i n d u c e d i n t h e c e l l b y t h e s t r e s s r e l i e f o f t h e o v e r c o r e . 97 5 . 3 T H E I N - S I T U S T R E S S M E A S U R E M E N T S T h e i n - s i t u s t r e s s m e a s u r e m e n t s a t t h e M c L e l l a n M i n e c o m m e n c e d i n t h e s h a f t s t a t i o n o n t h e 370 m L e v e l . In o r d e r to m i n i m i z e t h e s t r e s s i n f l u e n c e o f t h e s h a f t s t a t i o n i t s e l f , t h e H X h o l e w a s d r i l l e d i n o n e c o r n e r a t 4 5 ° to t h e w a l l s of t h e s t a t i o n . T h i s h o l e w a s a d v a n c e d f o r a p p r o x i m a t e l y 9 . 1 m p r i o r t o t h e i n s t a l l a t i o n o f t h e f i r s t c e l l ( F i g u r e 5 . 3 ) . T h e two foo t E X p i l o t h o l e w a s t h e n d r i l l e d a n d t h e f i r s t H . I . c e l l w a s i n s t a l l e d . U n f o r t u n a t e l y , t h e g r o u t w a s too s t i f f a n d d i d no t e x t r u d e p r o p e r l y w i t h i n t h e a n n u l u s b e t w e e n t h e c e l l a n d t h e w a l l s o f t h e h o l e . In a d d i t i o n t h e c e l l - r o c k o v e r c o r e c o m p o s i t e b r o k e d u r i n g t h e d r i l l i n g a n d a b i a x i a l t e s t c o u l d no t b e c o m p l e t e d . T h e s e c o n d a n d t h i r d o v e r c o r e s i n t h e h o l e o n t h e 370 m L e v e l w e r e c o m p l e t e d w i t h n o f u r t h e r p r o b l e m s . T h e f i r s t t e s t o n t h e 240 m L e v e l ( F i g u r e 5 . 4 ) w a s a l s o u n s u c c e s s f u l . A l t h o u g h t h e i n s t a l l a t i o n p r o c e d u r e s w e r e f o l l o w e d c o r r e c t l y , t h e p l u n g e r s t a r t e d to b i n d w i t h i n t h e H . I . c e l l d u r i n g t h e e x t r u s i o n o f t h e g r o u t . T h u s , t h e r e s t o f t h e g r o u t c o u l d no t b e e x t r u d e d . W h e n t h e c e l l w a s r e t r i e v e d t h e p i s t o n a n d t h e w o o d e n r o d r e m a i n e d i n t h e E X h o l e . T h e E X N MINE SHAFT SCALE 0 10 20 I I METRES OVERCORE HOLE #1 3 7 0 m L E V E L P L R N OVERCORE NO. 1 2 3 HOLE DEPTH m. 8.93 S.S1 10.36 O V E R C O R E H O L E D E T R I L S F i g u r e 5 . 3 - L o c a t i o n of 370 m L e v e l S i t e MINE SHAFT 10 N SCALE 10 -t-METRES 20 =1 V 2 4 0 m L E V E L P L A N OVERCORE HOLE #2 OVERCORE NO. HOLE DEPTH m 7.14 m B.23 9.27 O V E R C O R E H O L E D E T R I L S F i g u r e 5 .4 - L o c a t i o n of 240 m L e v e l S i t e 100 h o l e , p l u n g e r a n d r o d w e r e d r i l l e d o u t w i t h a n H X b i t a n d a n e w E X p i l o t h o l e w a s d r i l l e d . T h e n e x t two t e s t s o n t h e 240 m L e v e l w e r e c o m p l e t e d s u c c e s s f u l l y . D u r i n g t h e o v e r c o r i n g of t h e t h i r d c e l l t h e H . I . c e l l - r o c k c o m p o s i t e b r o k e a l o n g t h e s t r a i n g a u g e s a n d a b i a x i a l t e s t c o u l d n o t b e c o m p l e t e d f o r t h e o v e r c o r e . T h e r e f o r e o n l y f o u r o f t h e s e v e n a t t e m p t e d s t r e s s m e a s u r e m e n t s y i e l d e d s u f f i c i e n t d a t a f o r i n t e r p r e t a t i o n . F r o m v a r i o u s c a s e h i s t o r i e s r e v i e w e d b y t h e a u t h o r t h i s s u c c e s s r a t e a p p e a r s to b e a b o u t t h e n o r m . T h e s u c c e s s r a t e i n c r e a s e s s i g n i f i c a n t l y o n l y w h e n b o t h t h e t e c h n i c a l a n d d i a m o n d d r i l l c r e w s a r e f u l l y e x p e r i e n c e d at t h e s e m e a s u r e m e n t s . 101 5 . 4 D A T A A N A L Y S I S 5 . 4 . 1 A n a l y s i s of S t r a i n R e l i e f C u r v e s T h e s t r a i n r e l i e f v s t ime p l o t s o b t a i n e d f r o m t h e o v e r c o r i n g a r e g i v e n i n A p p e n d i x X I V . T h e i n t e r p r e t a t i o n of t h e s t r a i n r e l i e f c u r v e s w a s c o m p l e t e d i n t w o s t a g e s . F i r s t t h e c u r v e s w e r e e x a m i n e d w i t h r e s p e c t to t h e o v e r c o r i n g a c t i v i t y to e x a m i n e a n y m a j o r e f f e c t s of t h e a c t i v i t y o n t h e s t r a i n r e l i e f c u r v e s . N e x t t h e c u r v e s w e r e c o m p a r e d w i t h t h e d i a g n o s t i c c u r v e s ^ g i v e n i n F i g u r e 5 . 5 to d e t e r m i n e i f t h e o v e r a l l d a t a o b t a i n e d w a s m e a n i n g f u l a n d i f a d j u s t m e n t o f t h e c u r v e s w a s p o s s i b l e a n d / o r n e c e s s a r y . W h e r e a d j u s t m e n t to t h e c u r v e s w a s n e c e s s a r y , a l t e r n a t i v e p o s s i b l e a d j u s t m e n t s w e r e p l o t t e d a n d r e v i e w e d w i t h r e s p e c t to e a c h o t h e r a n d to t h e d i a g n o s t i c c u r v e s . T h i s r e v i e w r e s u l t e d i n a d j u s t e d s t r a i n r e l i e f c u r v e s f o r O v e r c o r e N o . 2 a n d 3 ( A p p e n d i x X V ) . A f t e r t h e i n t e r p r e t a t i o n of t h e c u r v e s w a s c o m p l e t e d t h e a c t u a l s t r a i n r e l i e f i n c u r r e d d u e to t h e r e l e a s e o f s t r e s s was d e t e r m i n e d f r o m t h e c u r v e s . T h e a c t u a l s t r a i n r e l i e f i n c u r r e d w a s t a k e n as t h e c h a n g e i n s t r a i n f r o m t h e s t a r t o f o v e r c o r i n g 102 Ovtnconto Qirouicl P l A M t Of 1 * i t t c M i l t t n i M l 3 CIRCUH. - FINITE ELEMENT Predic ted fo na of e t r e a a - r e l l e f c u r v « In • t r i a x i a l s t r a i t f i e l d for each diametral a t r a l n • I D I O T , obtained by superpos i t ion of s t r a i n coa-poncnt i . Curve 1 : Hypothet ica l diametral s t r a i n due to removal of r a d i a l compressive etrese on ly . Curva 2 : 01 A A * t r a l at ra in due to ten* H e a t r«a • concentrat ion of a J i l a l a t r t s s In a [ r a n t v « r t * • a c t i o n at tha leading edge of tna overcor ing annular groove, Curva 3 : Diametral s t r a i n due to Polsson contrac t ion of cor t upon removal of a x i a l compreaalve s t r e s s ( a large magnitude • t r e s s in t h i s example). Curve 4 i Resultant of curves 1 , 2 and 1, aa observed by diametral s t r a i n sensors in Instrument. AXIAL - TIKITE ELEMENT Pred ic ted form of s t r e s s - r e l i e f curve lo a t r i a x i a l s tress f i e l d for each a x i a l s t r a i n eenaor, obtained by superpoai t lon of s t r a i n components. Curve It Hypothet ica l a x i a l s t r a i n due to removal of large a x i a l compressive atreaa o n l y . Curve 2 : A x i a l s t r a i n due to compressive • t res s concentrat ion of r a d i a l s t r e s s , in the a x i a l d i r e c t i o n , at the loading edge of trie overcor ing annular groove. Curve 3 : A x i a l s t r a i n due to a x i a l Foleson contrac t ion of core upon removal of r e l a t i v e l y small r a d i a l compressive s t r e s s . Curve 4 : Resultant of curves 1, 2 and 3 , aa obaarved by a x i a l s t r a i n aansors In Instrument. puwi* o r _ 2 ANCLE - « M I T E ELEMENT Predic ted form of s t r e s s - r e l i e f curve i n a-t r i a x i a l atress f i e l d for each diagonal s t r a i n tensor , obtained aa the mean of the diametral and a x i a l a t r e a a - r e l l e f curvea . Curve l i Reeulant a t r e a s - r e l l e f curve for diametral e t r a l o aensora, from F i g . 3 . Curve 2 : Resultant a t r e s s - r e l l e f curve for a x i a l s t r a i n sensors , from F i g . 4 . Curve 3 t Ha an of curves 1 and 2 , aa observed by diagonal s t r a t a u n i o n In Instrument. O V C K C O A C D O l f T A N C t OVCRCOIING OtSUNCf (mmI Gauge F i g u r e 5.5 - D i a g n o s t i c C u r v e s f o r I n t e r p r e t a t i o n o f O v e r c o r i n g T e s t R e s u l t s 103 to t h e s t r a i n l e v e l w h e n o v e r c o r i n g h a d p r o g r e s s e d to a d i s t a n c e of 15 c m p a s t t h e s t r a i n g a u g e s . 5.4.2 A n a l y s i s of B i a x i a l T e s t R e s u l t s T h e s t r e s s - s t r a i n c u r v e s o b t a i n e d f r o m t h e b i a x i a l t e s t s ( A p p e n d i x X V I ) w e r e e x a m i n e d to d e t e r m i n e w h e t h e r o r no t t h e o v e r c o r e d r o c k i s i s o t r o p i c . T h i s w a s c o m p l e t e d b y c o m p a r i n g t h e a v e r a g e o f t h e a x i a l a n d c i r c u m f e r e n t i a l r e s p o n s e s f r o m e a c h o f r o s e t t e s A a n d C w i t h t h e s t r a i n r e s p o n s e f r o m t h e 4 5 ° g a u g e f r o m e a c h r o s e t t e . If t h e y c o m p a r e f a v o u r a b l y , t h e s t r a i n r e s p o n s e i s i s o t r o p i c . In a d d i t i o n t h e s t r a i n r e s p o n s e of g a u g e s 2, 6 a n d 8 ( c i r c u m f e r e n t i a l ) a r e c o m p a r e d . S i m i l a r r e s p o n s e s i n d i c a t e t h a t t h e r o c k i s n e a r l y h o m o g e n e o u s . If t h e r a t i o o f t h e m a x i m u m to t h e m i n i m u m m o d u l u s e x c e e d s 1.3 t h e r e s u l t s f r o m t h e o v e r c o r i n g i s s u s p e c t . T h e l a s t s t e p i n t h e i n t e r p r e t a t i o n o f t h e b i a x i a l t e s t r e s u l t s i n v o l v e d d e t e r m i n i n g Y o u n g ' s M o d u l u s a n d P o i s s o n ' s R a t i o f r o m t h e c u r v e s . T h e a v e r a g e s l o p e of t h e u n l o a d i n g p o r t i o n of t h e c u r v e s f o r g a u g e s 2, 6 a n d 8 a r e e q u a l to Y o u n g ' s M o d u l u s . T h e t h r e e r e s u l t a n t v a l u e s w e r e a v e r a g e d to d e t e r m i n e t h e Y o u n g ' s M o d u l u s f o r t h e r o c k o v e r c o r e . F i n a l l y , to o b t a i n t h e 104 P o i s s o n ' s R a t i o i n v o l v e d c a l c u l a t i n g t h e r a t i o of t h e a v e r a g e s l o p e o f g a u g e 1 to t h e a v e r a g e s l o p e o f g a u g e 2 a n d t h e r a t i o o f g a u g e 7 to g a u g e 8 . T h e P o i s s o n ' s R a t i o of t h e r o c k o v e r c o r e w a s t h e n c a l c u l a t e d f r o m t h e a v e r a g e o f t h e a b o v e r a t i o s . A s a n e x t r a c h e c k , t h e s e r e s u l t s w e r e c o m p a r e d to t h e r e s u l t s o f u n i a x i a l c o m p r e s s i o n t e s t s p e r f o r m e d o n d r i l l c o r e f r o m t h e M c L e l l a n M i n e ( C h a p t e r 4 ) . 5 . 4 . 3 E x a m i n a t i o n of S e c t i o n e d O v e r c o r e T h e l a s t s t e p i n t h e d a t a a n a l y s i s i n v o l v e d c u t t i n g t h e H . I . c e l l - r o c k o v e r c o r e c o m p o s i t e i n t o s e c t i o n s w i t h a d i a m o n d s a w a n d e x a m i n i n g t h e b o n d of t h e c e l l . In a d d i t i o n , t h e o r i e n t a t i o n o f t h e c e l l i n t h e h o l e w a s o b s e r v e d b y e x a m i n i n g t h e f l o w o f e x c e s s g r o u t . A s t h e e x c e s s g r o u t f l o w e d a l o n g t h e b o t t o m o f t h e h o l e , t h e o r i e n t a t i o n o f t h e c e l l w i t h r e s p e c t to t h e b o t t o m of t h e h o l e c o u l d b e m e a s u r e d . T h u s , t h e o r i e n t a t i o n of t h e g a u g e s w a s a c c u r a t e l y d e t e r m i n e d . 105 5.4.4 G e n e r a l It s h o u l d b e n o t e d t h a t t h e m e t h o d s u s e d to o b t a i n v a l u e s f r o m O v e r c o r e N o . 3 a r e b a s e d u p o n t h e r e f e r e n c e " D i a g n o s t i c S t r a i n R e l i e f C u r v e s i n S t r e s s M e a s u r e m e n t b y O v e r c o r i n g " - * a n d t h r o u g h w o r k p e r f o r m e d b y M i l l e r e t a l . ^ ^ 3 5 j n e a d j u s t e d c u r v e s r e f l e c t t h e s h a p e o f t h e c u r v e s o b t a i n e d f r o m t h e o t h e r o v e r c o r e s a n d a l o g i c a l e x t e n s i o n o f t h e d r i l l i n g p r o c e s s a n d o b s e r v a t i o n s m a d e d u r i n g o v e r c o r i n g . T h u s , t h e s e c u r v e s a r e , a t b e s t , o n l y a p p r o x i m a t i o n s . T h e i n - s i t u s t r e s e s w e r e c a l c u l a t e d f r o m t h e s e c u r v e s o n l y to c o n f i r m o r r e j e c t t h e r e s u l t s o b t a i n e d f r o m O v e r c o r e N o . 2 . 106 5 . 5 R E S U L T S T h e i n - s i t u s t r e s s c o n d i t i o n s , c a l c u l a t e d f r o m t h e d a t a o b t a i n e d a f t e r t h e a n a l y s e s w e r e c o m p l e t e d , a r e s u m m a r i z e d i n T a b l e 5 . 1 . 5 . 6 D I S C U S S I O N 5 . 6 . 1 S t r e s s M a g n i t u d e s It c a n b e s e e n f r o m T a b l e 5 .1 t h a t t h e c a l c u l a t e d i n - s i t u s t r e s s c o n d i t i o n s f o r e a c h l e v e l a r e i n c l o s e a g r e e m e n t . I n a d d i t i o n , f r o m F i g u r e 5 . 6 a n d 5 .7 i t i s a p p a r e n t t h a t t h e c a l c u l a t e d i n - s i t u v e r t i c a l a n d m a x i m u m h o r i z o n t a l s t r e s s e s c o m p a r e f a v o u r a b l y w i t h o t h e r v a l u e s o b t a i n e d a r o u n d t h e w o r l d . 7 M o r e s p e c i f i c a l l y , t h e v a l u e s a l s o c o m p a r e f a v o u r a b l y w i t h t h e r e s u l t s of o t h e r i n - s i t u s t r e s s m e a s u r e m e n t s c o m p l e t e d i n N o r t h e r n M a n i t o b a . 9 , 2 1 , 3 3 ( F i g u r e s 5 .8 a r i d 5 . 9 ) . P a k a l n i s 4 2 m e a s u r e d t h e i n - s i t u s t r e s s a t R u t t a n M i n e at a d e p t h of 661 m . A l t h o u g h t h e a c t u a l c a l c u l a t e d s t r e s s e s a t t h e M c L e l l a n M i n e a r e no t d i r e c t l y c o m p a r a b l e w i t h t h o s e o b t a i n e d b y P a k a l n i s , ( T a b l e 5 . 1 ) t h e r a t i o s of m a j o r , i n t e r m e d i a t e a n d 107 m i n o r p r i n c i p a l s t r e s s e s to t h e v e r t i c a l s t r e s s a r e . T h e c a l c u l a t e d v a l u e s o f t h e K f a c t o r d o , h o w e v e r , d e p a r t f r o m t h e t h e o r e t i c a l v a l u e s s u g g e s t e d b y H e r g e t . 2 1 i t i s f e l t t h a t t h i s d e p a r t u r e i s a t t r i b u t a b l e to t h e f a c t t h a t t h e ma jo r p r i n c i p a l s t r e s s i s v i r t u a l l y c o n s t a n t f r o m t h e 240 m L e v e l to t h e 370 m L e v e l . A l t h o u g h t h i s c o n d i t i o n i s q u i t e r e a s o n a b l e f o r s t r e s s c o n d i t i o n s a t a g i v e n s i t e , i t d o e s n o t c o m p a r e w i t h o v e r a l l c u r v e s o b t a i n e d b y a " b e s t f i t " a p p r o a c h to d a t a f r o m v a r i o u s s i t e s . T h e r e f o r e , t h i s c o m p a r i s o n i s l i k e l y v a l i d o n l y f o r o r d e r o f m a g n i t u d e e s t i m a t e s . In a d d i t i o n , t h e d e p a r t u r e f r o m t h e o r e t i c a l v a l u e s m a y b e i n p a r t d u e to t h e l i m i t a t i o n s of t h e s t r a i n m e a s u r i n g d e v i c e s . B e c a u s e t h e V i s h a y S t r a i n R e c o r d e r a n d B a l a n c e U n i t s w e r e u s e d a n d d u e to t h e s p e e d at w h i c h m e a s u r e m e n t s h a d to b e t a k e n , t h e r e a d i n g s a r e l i k e l y o n l y a c c u r a t e to w i t h i n +10 m i c r o s t r a i n . A s t h e b u l k o f t h e m e a s u r e d s t r a i n r e l i e f v a l u e s w e r e i n t h e o r d e r o f 100 to 200 m i c r o s t r a i n s , a n i n h e r e n t e r r o r o f +5%-10% e x i s t e d . 108 OVERCORE NO. 2 3 A 5 RUTTAN , MINE LEVEL 370m 370ra 2A0m 2A0ra 661m PRINCIPAL STRESS MAGNITUDE ° ' ( B ) 5(C) ° 3 20.02 9.20 8.75 19.65 12.A2 9.86 20.98 8.63 6.58 21.31 8.A3 7.7A AA.8 to 120.7 20.00 to 32.Al 13.79 to 28.A7 PRINCIPAL STRESS ORIENTATION ° 1 ° 3 129.A"/- 2.8" 38.0°/-26.5° A5.0°/ 63.3' 1A1.2°/- 6.A° A7.8°/-27.9° 63.0°/ 61.3° A.5°/ 5.6* 96.8°/21.9* 260.9°/67.3° 176.1°/-5.8° 267.A°/-12.1° See Figure IA 2A1.0°/76.5 RATIO A/B/C 1/0.A6/0.AA 1/0.63/0.50 1/0.A1/0.31 1/0.A0/0.36 1/0.A/0.3 VERTICAL STRESS OV 8.87 10.5A 7.01 7.9.1 17.86 to 39.30 HORIZONTAL STRESSES oH(N-S) oH(E-W) ^ F )13.50 ( F )15.61 16.6A 1A.75 20.78 8.A1 21.11 8.A6 AO.68 to 96.9A 20.00 to A1.37 o H(AVE.) ( G )lA.56 15.70 1A.60 1A.79 30.3A to 7A.67 FACTOR E/D F/D G/D(H) 1.52 1.76 1.6A 1.58 1.A0 1.A9 2.96 1.20 2.08 2.67 1.07 1.87 1.6 to 2.6 0.9 to 1.2 1.3 to 1.9 PRINCIPAL TO VERTICAL STRESS RATIO A/D B/D C/D 2.26 1.0A 0.99 1.86 1.18 0.9A 2.99 1.23 0.9A 2.69 1.07 0.98 1.8 to 3.1 0.8 to 1.2 0.5 TO 0.8 OTK THEORETICAL) (2.96 gZ) I 10.61 10.61 7.08 . 7.08 17.8 OJJ( THEORETICAL) (9.86+.037H) J 23.55 23.55 18.7A 18.7A 3A.0 " (THEORETICAL) K aH 2.22 2.22 2.6A 2.6A 1.9 PER CENT DIFFERENCE 1-D/I 1-H/K 16X 26% IX 33Z IX 2 U IIX 29% OX to 119* 0% to 32Z Note: A l l stress magnitudes are given i n Mpa. A l l stress orientations are given in deg Tab le 5.1 Eva lua t i on of Ca lcu la ted S t r e s s e s 109 .5 1.0 E 1.5 D_ LU Q 2.0 2,5 •X-,crz = 0.027 z \ \ • M C L E L L A N MINE • OTHERS \ \ 3.0 10 20 30 40 50 V E R T I C A L STRESS MPa, 60 70 Figure 5.6 - Variation in Vertical Stress with Depth from Values Obtained Worldwide 110 F i g u r e 5.7 - V a r i a t i o n i n H o r i z o n t a l S t r e s s to V e r t i c a l S t r e s s R a t i o f r o m V a l u e s O b t a i n e d W o r l d w i d e I l l 0.5 1.0 / / / ^hove ,251.68 crz z lm) .14 N • MCLELLAND • OTHERS CL La 2,0 2.5 3.0 0.5 i.O 1.5 2.0 °h ave 2.5 3.0 F i g u r e 5.8 - V a r i a t i o n i n H o r i z o n t a l S t r e s s to V e r t i c a l S t r e s s R a t i o f r o m V a l u e s O b t a i n e d f r o m N o r t h e r n M a n i t o b a 112 0 0.5 - \ x - c r h „ = 9.86 MPa+ 0 .037 MPo/m • •\. \ n ave \ - ~ - % Q v e = l 2 . 3 6 M P a + 0.059 MPa/m E X r— a. UJ Q 1.0 1.5 -crh a v e = 3 3 . 4 l MPa 4-0.011 MPa/m 1 MCLE L L A N D OTHERS 2.0 2.5 I I I I t 5 0 100 150 200 A V E R A G E HORIZONTAL S T R E S S MPa 250 F i g u r e 5.9 - V a r i a t i o n i n H o r i z o n t a l S t r e s s w i t h D e p t h i n N o r t h e r n M a n i t o b a 113 5 . 6 . 2 S t r e s s O r i e n t a t i o n s T h e c a l c u l a t e d o r i e n t a t i o n o f t h e p r i n c i p a l s t r e s s e s f o r t h e 240 m a n d 370 m L e v e l s a r e s h o w n o n e q u a l a r e a p o l a r n e t s i n F i g u r e 5 . 1 0 . In t h e s e p l o t s t h e s t r e s s i s o r i e n t e d w i t h r e s p e c t to M i n e N o r t h w h i c h i s 2 4 ° Wes t o f T r u e N o r t h . It i s o b v i o u s t h a t t h e t w o o r i e n t a t i o n s o b t a i n e d o n e a c h l e v e l a r e i n c l o s e a g r e e m e n t . W h e n t h e a v e r a g e s t r e s s o r i e n t a t i o n s a r e p l o t t e d w i t h r e s p e c t to T r u e N o r t h ( F i g u r e 5 . 1 1 ) , i t i s a p p a r e n t t h a t t h e o r i e n t a t i o n s a r e i n c l o s e a g r e e m e n t w i t h t h o s e o b t a i n e d b y P a k a l n i s 4 2 a t t h e R u t t a n M i n e . T h e a v e r a g e o r i e n t a t i o n of t h e m a j o r p r i n c i p a l s t r e s s ( F i g u r e 5 . 1 2 ) i s a p p r o x i m a t e l y 1 5 ° o f f p e r p e n d i c u l a r to t h e l o c a l s t r i k e o f t h e N o r t h S h e a r a n d v i r t u a l l y p e r p e n d i c u l a r to t h e f o l i a t i o n . T h e r e a r e t w o p o s s i b l e e x p l a n a t i o n s of t h i s p h e n o m e n o n . T h e r e s i d u a l t e c t o n i c s t r e s s e s a r e r e f l e c t e d b y t h e f o l i a t i o n a n d t h e N o r t h S h e a r m a y b e a p r e - e x i s t i n g s t r u c t u r e . A l t e r n a t i v e l y , t h e N o r t h S h e a r may h a v e o c c u r r e d d u r i n g t h e l a s t s t a g e of t e c t o n i s m w i t h s u b s e q u e n t s l i p a l o n g t h e f o l i a t i o n r e l i e v i n g t h e s t r e s s i n t h a t d i r e c t i o n . 114 F i g u r e 5 . 1 0 O r i e n t a t i o n of P r i n c i p a l S t r e s s e s o n B o t h L e v e l s + - 240 m L e v e l 0 - 370 m L e v e l 115 F i g u r e 5 . 1 1 C o m p a r i s o n of A v e r a g e O r i e n t a t i o n of P r i n c i p a l S t r e s s e s w i t h A v e r a g e O r i e n t a t i o n a t R u t t a n M i n e ° - M c L e l l a n M i n e + - R u t t a n M i n e 116 F i g u r e 5 . 1 2 C o m p a r i s o n of A v e r a g e O r i e n t a t i o n of P r i n c i p a l S t r e s s e s w i t h S t r u c t u r a l G e o l o g y © - 240 m L e v e l N o r t h S h e a r F o l i a t i o n 117 It s h o u l d a l s o b e n o t e d t h a t t h e a v e r a g e ma jo r 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 ( F i g u r e 5 . 1 3 ) i s n e a r p e r p e n d i c u l a r to t h e r e g i o n a l s t r i k e of t h e g e o l o g y a n d i n f a c t to t h e c o n t a c t b e t w e e n t h e m e t a s e d i m e n t s a t t h e s i t e a n d t h e i n t r u s i v e s to t h e n o r t h - w e s t . 118 )6T i U KEEWATIN | f RIVER *** MCLELLAN MINE % "V" 3 , - - - r i ,---'y 5 2 / COCKER AM L A K E LEGEND • D Intrusive, g ran i te \ 5 1 Intrusive, t ona l i t e ,g ran i t e r~4~| Wasekwan conglomerate 1 3 | Wasekwan sediments I 2 I Wasekwan f e l s i c gneiss 1 i 1 Wasekwan vo l can i cs and amphibo l i te Sca le 1 0 1 SYMBOLS Geologic boundary: • Approximate Assumed Fo l ia t ion Bedd ing 4 miles F i g u r e 5 . 1 3 - C o m p a r i s o n o f O r i e n t a t i o n o f M a j o r P r i n c i p a l S t r e s s w i t h R e g i o n a l G e o l o g y . N o t e t h a t g e o l o g i c a l u n i t s 5 a n d 6 a r e i n t r u s i v e . M a j o r 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 i n d i c a t e d b y S o l i d A r r o w s . 119 5 .7 C O N C L U S I O N S A f t e r c o m p a r i n g t h e r e s u l t s of t h e i n - s i t u s t r e s s m e a s u r e m e n t s c o m p l e t e d a t t h e - M c L e l l a n M i n e w i t h s t r e s s d e t e r m i n a t i o n s c o m p l e t e d a r o u n d t h e w o r l d a n d i n N o r t h e r n M a n i t o b a i t i s c o n c l u d e d t h a t t h e c a l c u l a t e d s t r e s s e s r e p r e s e n t a g o o d e s t i m a t i o n o f t h e a c t u a l i n - s i t u s t r e s s c o n d i t i o n s . It i s f u r t h e r c o n c l u d e d t h a t : 1) T h e c a l c u l a t e d v e r t i c a l s t r e s s e s c o r r e l a t e w i t h a t h e o r e t i c a l v e r t i c a l s t r e s s d u e to a s p e c i f i c g r a v i t y of a p p r o x i m a t e l y 2 . 9 6 , t h e a v e r a g e o b t a i n e d f r o m s p e c i f i c g r a v i t y t e s t s d i s c u s s e d i n C h a p t e r 4 . 2) T h e m a j o r p r i n c i p a l s t r e s s w a s f o u n d to b e v i r t u a l l y c o n s t a n t b e t w e e n t h e 240 m a n d 370 m L e v e l s . T h e m i n o r a n d 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 e s s h o w e d a n i n c r e a s e w i t h i n c r e a s i n g d e p t h . 3 ) T h e o r i e n t a t i o n of t h e m a j o r p r i n c i p a l s t r e s s i s p e r p e n d i c u l a r to t h e f o l i a t i o n of t h e m e t a - s e d i m e n t s , a n d 4 ) T h e N o r t h S h e a r a n d a s s o c i a t e d j o i n t i n g may no t b e r e l a t e d to t h e p r e s e n t s t r e s s r e g i m e . 120 S p e c i f i c a l l y i t i s c o n c l u d e d t h a t : 1) T h e ma jo r p r i n c i p a l s t r e s s i s n e a r l y p e r p e n d i c u l a r to t h e o r e b o d y at a n a z i m u t h o f 3 3 6 ° r e l a t i v e to m i n e n o r t h a n d a p l u n g e of 6 ° to t h e s o u t h - e a s t . 2 ) T h e 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 i s n e a r l y p a r a l l e l to t h e o r e b o d y a t an a z i m u t h of 6 8 ° r e l a t i v e to m i n e n o r t h a n d a p l u n g e of 6 ° to t h e n o r t h - w e s t . 3 ) T h e m i n o r p r i n c i p a l s t r e s s a c t s n e a r l y d o w n t h e d i p of t h e o r e b o d y a t a n a z i m u t h o f 2 1 ° r e l a t i v e to m i n e n o r t h a n d a p l u n g e o f 8 4 ° . In a d d i t i o n , t h e m a g n i t u d e o f t h e p r i n c i p a l s t r e s s e s b e t w e e n t h e 240 m L e v e l a n d 370 m L e v e l a r e e s t i m a t e d to b e : O j = 2 0 . 4 9 M p a G2 - 1 .13 (Tv CT3 = 0 . 9 6 OV w h e r e OV = 0 . 0 2 9 0 M P a / m C H A P T E R 6 L I T E R A T U R E REVIEW A N D E S T I M A T I O N OF E N G I N E E R I N G P R O P E R T I E S OF B A C K F I L L 122 6 . 0 I N T R O D U C T I O N H y d r a u l i c b a c k f i l l i s b e i n g u s e d s u c c e s s f u l l y i n s e v e r a l m i n e s to a l l o w a r e t r e a t m e t h o d of c u t - a n d - f i l l m i n i n g . T h e s t o p e s a r e m i n e d f r o m t h e b o t t o m t o w a r d s t h e s u r f a c e a n d t h e b a c k f i l l p r o v i d e s a w o r k i n g f l o o r f o r p e r s o n n e l a n d e q u i p m e n t . In a d d i t i o n , t h i s a l l o w s w e a k s t o p e w a l l s to b e " b u r i e d " b e l o w t h e w o r k i n g f a c e a n d t h e b a c k f i l l c o n f i n e s t h e l o o s e r o c k t h a t d e v e l o p s i n t h e s t o p e w a l l s . In r e c e n t y e a r s i t h a s b e e n r e a l i z e d t h a t as m i n i n g p r o g r e s s e s , e v e n u n c e m e n t e d , h y d r a u l i c b a c k f i l l d o e s a b s o r b a p o r t i o n o f t h e i n d u c e d s t r e s s e s . T h u s , t h e p i l l a r s b e t w e e n t h e s t o p e s a r e s u b j e c t e d to s o m e w h a t l o w e r s t r e s s c o n d i t i o n s a n d t h e s t o p e w a l l s t e n d to r e m a i n i n c o m p r e s s i o n . T h e p u r p o s e o f b a c k f i l l i n a h i g h e x t r a c t i o n c u t - a n d - f i l l m i n e i s t h e r e f o r e t w o f o l d . I n i t i a l l y , t h e b a c k f i l l m a t e r i a l m u s t p r o v i d e a s o u n d w o r k i n g f l o o r as q u i c k l y as p o s s i b l e . A s m i n i n g p r o g r e s s e s t h e b a c k f i l l s h o u l d p r o v i d e s u p p o r t p r e s s u r e to t h e s t o p e w a l l s . 6 . 1 M A T E R I A L P R O P E R T I E S R E Q U I R E D B e c a u s e t h e b a c k f i l l m a t e r i a l m u s t i n i t i a l l y p r o v i d e a s o u n d 123 w o r k i n g f l o o r as q u i c k l y as p o s s i b l e , i t m u s t h a v e t h e c a p a c i t y t o d r a i n q u i c k l y a n d y e t c o n s o l i d a t e s u f f i c i e n t l y to a l l o w t h e p a s s a g e of m i n e v e h i c l e s . In a d d i t i o n t h e p e r c o l a t i o n r a t e m u s t b e s u f f i c i e n t to e n s u r e t h a t e x c e s s p o r e p r e s s u r e s d o no t o c c u r w i t h i n t h e s t o p e a n d y e t l o w e n o u g h to p r e v e n t e r o s i o n of t h e f i n e m a t e r i a l i n t h e f i l l ( p i p i n g ) . T h u s , t h e c o n t r o l l i n g p a r a m e t e r s of h y d r a u l i c b a c k f i l l m a t e r i a l m u s t b e g r a i n s i z e d i s t r i b u t i o n a n d t h e g r a i n s h a p e . T o a l l o w w a t e r to d r a i n o f f q u i c k l y t h e g r a i n s s h o u l d b e r o u n d e d a n d t h e s i z e d i s t r i b u t i o n s h o u l d b e u n i f o r m . H o w e v e r , t h i s w o u l d no t p r o v i d e i d e a l c o n d i t i o n s f o r c o m p a c t i o n a n d / o r c o n s o l i d a t i o n . It i s t h e r e f o r e n e c e s s a r y to p i c k a n o p t i m u m g r a i n s i z e d i s t r i b u t i o n to m a x i m i z e b o t h t h e d r a i n a g e r a t e a n d c o n s o l i d a t i o n / c o m p a c t i o n c h a r a c t e r i s t i c s . T h e g r a i n s h a p e i s u s u a l l y no t c o n s i d e r e d i n t h e o p t i m i z a t i o n p r o c e s s b e c a u s e i t i s i n h e r e n t to t h e s o u r c e of t h e b a c k f i l l m a t e r i a l . H o w e v e r , i t d o e s a f f e c t t h e f o r m o f t h e o p t i m u m g r a i n s i z e d i s t r i b u t i o n c u r v e o f t h e b a c k f i l l m a t e r i a l . In a d d i t i o n to p r o v i d i n g a w o r k i n g f l o o r i n t h e s t o p e , t h e b a c k f i l l m a t e r i a l c a n p r o v i d e s u p p o r t to t h e s t o p e w a l l s . In o r d e r to m a x i m i z e t h e s u p p o r t p r e s s u r e p r o v i d e d b y t h e b a c k f i l l t h e i n p l a c e d e n s i t y o f t h e f i l l s h o u l d b e m a x i m i z e d . In c i v i l 124 e n g i n e e r i n g p r o j e c t s , t h i s i s n o r m a l l y a c h i e v e d b y u s i n g a w e l l - g r a d e d f i l l m a t e r i a l a n d b y c o m p a c t i o n of t h e b a c k f i l l as i t i s p l a c e d . H o w e v e r , b o t h o f t h e s e m e t h o d s r e s u l t i n l o w e r p e r c o l a t i o n r a t e s o f t h e w a t e r t h r o u g h t h e f i l l . In a d d i t i o n , c o m p a c t i o n of t h e f i l l m a t e r i a l as i t i s b e i n g p l a c e d i s d i f f i c u l t a n d e x p e n s i v e . In u n d e r g r o u n d c u t - a n d - f i l l m i n e s t h e s u b s e q u e n t b l a s t i n g a n d m i n e t r a f f i c a r e r e l i e d u p o n to c o m p a c t t h e b a c k f i l l . In o r d e r to o p t i m i z e t h e e n g i n e e r i n g c h a r a c t e r i s t i c s o f t h e b a c k f i l l , i t i s t h e r e f o r e n e c e s s a r y to c o n d u c t a d e t a i l e d t e s t p r o g r a m o n t h e b a c k f i l l m a t e r i a l to d e t e r m i n e : 1) G r a i n s i z e d i s t r i b u t i o n c u r v e s 2) P e r c o l a t i o n r a t e s 3 ) M a x i m u m a t t a i n a b l e d e n s i t y a n d t h e 4 ) O p t i m u m p u l p d e n s i t y f o r p l a c e m e n t . E v e n t h e n , t h e i n - p l a c e d e n s i t y a n d s t i f f n e s s o f t h e b a c k f i l l m a t e r i a l c a n o n l y b e e s t i m a t e d p r i o r to i n - s i t u t e s t i n g o f t h e p l a c e d b a c k f i l l . A t t h e M c L e l l a n M i n e t h e p r o b l e m i s c o m p o u n d e d b y t h e d e c i s i o n to u s e s a n d a n d g r a v e l f r o m g l a c i o f l u v i a l d e p o s i t s . A s t h e s e d e p o s i t s a r e h i g h l y v a r i a b l e i n g r a i n s i z e d i s t r i b u t i o n a n d p e r m e a b i l i t y , i t w i l l b e n e c e s s a r y to b l e n d m a t e r i a l s w i t h d i f f e r e n t e n g i n e e r i n g p r o p e r t i e s . T h u s , t h e q u a n t i t i e s o f t h e 1 2 5 v a r i o u s s o i l t y p e s m u s t b e a s c e r t a i n e d a n d a n o p t i m u m b l e n d m u s t b e d e t e r m i n e d t h a t w i l l s a t i s f y t h e r e q u i r e m e n t s o f t h e m i n e . A s t h e m a t e r i a l i s no t y e t a v a i l a b l e f o r t e s t i n g , r e a s o n a b l e e s t i m a t e s o f t h e e n g i n e e r i n g p r o p e r t i e s of t h e b l e n d e d b a c k f i l l m a t e r i a l m u s t b e m a d e p r i o r to a n y n u m e r i c a l a n a l y s i s of t h e s u p p o r t c a p a b i l i t y o f t h e b a c k f i l l . In a d d i t i o n t h e r e q u i r e m e n t s o f r e l a t i v e l y h i g h p e r c o l a t i o n r a t e ( q u i c k d r a i n a g e ) a n d e a r l y s t r e n g t h f o r m i n e t r a f f i c m u s t b e s a t i s f i e d . In o r d e r to d e t e r m i n e a r e a s o n a b l e r a n g e f o r t h e s e c h a r a c t e r i s t i c s , a n e x h a u s t i v e l i t e r a t u r e r e v i e w of h y d r a u l i c b a c k f i l l w a s c o n d u c t e d . T h e r e s u l t s of t h i s r e v i e w a r e p r e s e n t e d i n two s e c t i o n s d e f i n i n g t h e e a r l y s t r e n g t h c h a r a c t e r i s t i c s of b a c k f i l l a n d a t h i r d d e f i n i n g t h e l o n g e r t e r m s t i f f n e s s p a r a m e t e r s r e q u i r e d f o r n u m e r i c a l a n a l y s i s . 126 6 . 2 P E R C O L A T I O N R A T E 6 . 2 . 1 G e n e r a l A t t h e 6 t h C o m m o n w e a l t h M i n i n g a n d M e t a l l u r g i c a l C o n g r e s s , i n 1 9 5 7 , C r a y s t o n , V a n L o o n a n d H e a t h e r l 2 s t a t e d t h a t " I n t h e a u t h o r s ' o p i n i o n t a i l i n g s c o n t a i n i n g o v e r 70 p e r c e n t m i n u s 2 0 0 - m e s h m a t e r i a l a n d f i n e r c o u l d no t b e s u c c e s s f u l l y u s e d f o r b a c k f i l l w i t h o u t f i r s t t h o r o u g h c l a s s i f i c a t i o n to r e m o v e t h e f i n e r m a t e r i a l . S o l i d s of p u l p s of t h i s f i n e n e s s i n v a r i a b l y s e t t l e o u t i n t o a j e l l y - l i k e m a s s o r a t b e s t t h e c o n s i s t e n c y of p u t t y " C l e a r l y , a m a t e r i a l w i t h " t h e c o n s i s t e n c y o f p u t t y " w o u l d no t p r o v i d e a s u i t a b l e w o r k i n g f l o o r f o r m i n i n g e q u i p m e n t . H o w e v e r , a t t h e M a d s e n R e d L a k e M i n e , t h e h y d r a u l i c f i l l w a s p l a c e d at a p u l p d e n s i t y o f 55% d r y s o l i d s b y w e i g h t o r o v e r 65% w a t e r b y v o l u m e . T h i s l i k e l y c a u s e d s e g r e g a t i o n of t h e f i l l m a t e r i a l i n t o h o r i z o n t a l l a y e r s , l e a v i n g t h e f i n e s to s e t t l e o u t i n t h e top l a y e r of e a c h p o u r . T h u s , t h e t o p l a y e r w o u l d b e v i r t u a l l y i m p e r v i o u s to w a t e r f l o w a n d w o u l d b e u n a b l e to d r a i n q u i c k l y . In 1966 W o o d r u f f ^ 9 w r o t e , " T h e mos t i m p o r t a n t s i n g l e 127 r e q u i r e m e n t f o r h y d r a u l i c f i l l i s t h a t i t b e p e r m e a b l e e n o u g h to d r a i n a n d s o l i d i f y w i t h i n a f e w h o u r s t i m e . It i s g e n e r a l l y a c c e p t e d as a r u l e o f t h u m b t h a t a p e r m e a b i l i t y r a t e o f 4 i n . p e r h o u r i s t h e m i n i m u m a c c e p t a b l e f o r h y d r a u l i c f i l l " . H o w e v e r , h e d i d no t d i f f e r e n t i a t e b e t w e e n c u t - a n d - f i l l s t o p e s a n d o p e n s t o p e s . It w a s r e c o g n i z e d b y t h a t t ime t h a t t h e p e r m e a b i l i t y o f t h e f i l l w a s d e p e n d e n t to a l a r g e d e g r e e o n t h e m a t e r i a l s b e l o w 2 0 0 - m e s h i n s i z e . In a d d i t i o n i t w a s k n o w n t h a t t h e d e g r e e of d e p e n d e n c y v a r i e d w i t h t h e d i s t r i b u t i o n of m a t e r i a l b o t h a b o v e a n d b e l o w t h e 2 0 0 - m e s h s i z e d g r a i n s . H o w e v e r , t h e i m p o r t a n c e o f g r a i n s h a p e w a s no t w e l l k n o w n at t h a t t i m e . B y 1973 t h e d e p e n d e n c e o f t h e p e r c o l a t i o n r a t e o n : 1 ) T h e c o e f f i c i e n t o f u n i f o r m i t y C u =-^G_ D 10 2) T h e g r a i n s h a p e a n d 3) T h e d e g r e e of c o m p a c t i o n o r r e l a t i v e d e n s i t y ^max w a s w e l l e s t a b l i s h e d . D i c k o u t l ^ , i n h i s k e y n o t e a d d r e s s a t t h e J u b i l e e S y m p o s i u m 128 o n M i n e F i l l i n g , n o t e d w i t h t h e t h e n c u r r e n t s t a t e o f t h e a r t t h a t : " P e r c o l a t i o n r a t e s r a n g e d f r o m 2 to 14 i n c h e s p e r h o u r w h i l e t h e c o e f f i c i e n t o f u n i f o r m i t y r a n g e d f r o m 2 . 4 to 8 . 0 . " T h e f i r s t m e t h o d i c a l i n v e s t i g a t i o n , f o u n d i n t h e l i t e r a t u r e , o f t h e p a r a m e t e r s a f f e c t i n g p e r c o l a t i o n r a t e w a s p r e s e n t e d b y H e r g e t a n d De K o r o m p a y 2 2 i n 1 9 7 8 . In t h e p a p e r p r e s e n t e d at t h e 1 2 t h C a n a d i a n R o c k M e c h a n i c s s y m p o s i u m , t h e a u t h o r s p o i n t e d o u t t h e d e p e n d e n c e of t h e h y d r a u l i c c o n d u c t i v i t y ( p e r c o l a t i o n r a t e ) o f g r a n u l a r m a t e r i a l o n 1) W a t e r t e m p e r a t u r e 2) D e g r e e o f s a t u r a t i o n o f t h e f i l l m a t e r i a l 3 ) T h e g r a i n s i z e d i s t r i b u t i o n a n d 4 ) P o r o s i t y f o r a g i v e n f i l l m a t e r i a l . T h e y p o i n t e d o u t t h a t t h e p e r c o l a t i o n r a t e as t e s t e d i n t h e l a b o r a t o r y f o r a g i v e n f i l l m a t e r i a l w i l l c h a n g e 10% f o r e v e r y 4 ° C c h a n g e i n w a t e r t e m p e r a t u r e a n d c a n e a s i l y c h a n g e 50% f o r e a c h 10% c h a n g e i n d e g r e e o f s a t u r a t i o n . I n a d d i t i o n t h e y f o u n d t h a t t h e p e r c e n t a g e of - 4 0 0 m e s h ( -38 m i c r o n s ) m a t e r i a l to a l a r g e d e g r e e c o n t r o l l e d t h e s a t u r a t e d p e r c o l a t i o n r a t e i n t h e f i l l . T h e y s u g g e s t e d t h a t t h e 129 p e r c o l a t i o n r a t e s t a r t s to d r o p b e l o w 5 c m / h r i f t h e p e r c e n t a g e o f s l i m e s ( -400 m e s h ) i n c r e a s e s a b o v e t h e r a n g e of 12% to 25%. T h e y a l s o s u g g e s t e d t h a t a c c o r d i n g to K o z e n y ' s f o r m u l a k = n? 5 S v 2 ( i _ n ) 2 w h e r e k = p e r c o l a t i o n r a t e S v = t o t a l g r a i n s u r f a c e u n i t v o l u m e of f i l l ( a n e x p r e s s i o n of g r a i n s h a p e & s i z e ) a n d n = p o r o s i t y " A c h a n g e i n p o r o s i t y f r o m 0 . 3 7 to 0 . 4 7 w o u l d r e s u l t i n a 2 . 8 f o l d i n c r e a s e i n p e r c o l a t i o n r a t e " . A p p l y i n g t h i s i n r e v e r s e to d u p l i c a t e t h e c o m p a c t i o n o f h y d r a u l i c b a c k f i l l w i t h t i m e , a r e d u c t i o n i n p o r o s i t y f r o m 0 . 4 7 t o 0 . 3 7 w o u l d r e s u l t i n a d r o p o f p e r c o l a t i o n r a t e of a b o u t 64%. P r o b a b l y t h e mos t i m p o r t a n t e f f e c t H e r g e t a n d D e K o r o m p a y d i s c u s s e d i n t h e i r p a p e r i s t h e e f f e c t o f s e g r e g a t i o n o f t h e f i l l r e s u l t i n g i n s u b - h o r i z o n t a l l a y e r i n g . T h i s s e g r e g a t i o n c a n c a u s e o v e r a l l l o w e r i n g of t h e r a t e of w a t e r p e r c o l a t i o n v e r t i c a l l y t h r o u g h t h e f i l l . T h e y a l s o s t a t e t h a t p e r c o l a t i o n r a t e s i n t h e h o r i z o n t a l d i r e c t i o n a r e o f t e n d o u b l e t h o s e i n t h e v e r t i c a l d i r e c t i o n . T h i s p h e n o m e n o n i s l a r g e l y d e p e n d e n t u p o n t h e p u l p d e n s i t y o f t h e h y d r a u l i c b a c k f i l l d u r i n g e m p l a c e m e n t a n d t h e 130 r a t e of e m p l a c e m e n t . P u l p d e n s i t i e s g r e a t e r t h a n 65% d r y s o l i d s b y w e i g h t u s u a l l y r e s u l t i n m i n i m a l s e g r e g a t i o n w h e n t h e p l a c e m e n t r a t e i s s u f f i c i e n t to p r e v e n t t h e s e t t l e m e n t of p a r t i c l e s . In 1 9 8 3 , P a t c h e d s u m m a r i z e d t h e c h a r a c t e r i s t i c s of t h e b a c k f i l l m a t e r i a l u s e d i n p r o d u c i n g m i n e s . H e f o u n d t h a t mos t f i l l m a t e r i a l c u r v e s s h o w l e s s t h a n 25% of m i n u s 74 m i c r o n m a t e r i a l . H e s u g g e s t e d t h a t a c o e f f i c i e n t o f u n i f o r m i t y i n t h e r a n g e o f 5 to 7 w o u l d r e p r e s e n t g o o d g r a d i n g f o r h y d r a u l i c b a c k f i l l . M a t e r i a l w i t h l o w e r v a l u e s of t h e c o e f f i c i e n t o f u n i f o r m i t y w i l l u s u a l l y h a v e a n e x c e s s i v e p e r c o l a t i o n r a t e , l ow d e n s i t y a n d e x c e s s i v e c o m p r e s s i o n a f t e r e m p l a c e m e n t . M a t e r i a l w i t h h i g h e r v a l u e s w i l l h a v e a l o w p e r c o l a t i o n r a t e . T h e f a c t o r s a f f e c t i n g t h e i n - s i t u p e r c o l a t i o n r a t e of t h e h y d r a u l i c f i l l c a n t h e r e f o r e b e s u m m a r i z e d i n t o t w o c a t e g o r i e s c o n s i s t i n g of f a c t o r s i n h e r e n t to t h e f i l l m a t e r i a l a n d f a c t o r s r e l a t e d p r i m a r i l y to t h e p l a c e m e n t of t h e f i l l . T h e f a c t o r s a f f e c t i n g t h e p e r c o l a t i o n r a t e t h a t a r e i n h e r e n t to t h e f i l l m a t e r i a l a r e t h e g r a i n s h a p e , t h e g r a i n s i z e d i s t r i b u t i o n a n d t h e p o r o s i t y . A s t h e f i n a l s e l e c t i o n o f f i l l m a t e r i a l f o r t h e M c L e l l a n M i n e h a s no t y e t b e e n m a d e , o n l y e s t i m a t e s c a n b e m a d e of t h e e f f e c t o f t h e s e p a r a m e t e r s o n t h e p e r c o l a t i o n r a t e . T h u s , t h e p e r c o l a t i o n r a t e i t s e l f c a n o n l y b e e s t i m a t e d f r o m l i m i t e d i n i t i a l l a b o r a t o r y t e s t i n g a n d f r o m d a t a 131 a v a i l a b l e i n t h e l i t e r a t u r e . T h e e f f e c t o f f a c t o r s r e l a t e d p r i m a r i l y to t h e p l a c e m e n t of t h e f i l l a r e t h e w a t e r t e m p e r a t u r e , t h e d e g r e e o f s a t u r a t i o n , t h e p l a c e m e n t p u l p d e n s i t y a n d t h e s e g r e g a t i o n o f t h e f i l l . A s t h e s e p a r a m e t e r s c a n n o t b e a c c u r a t e l y e s t i m a t e d w i t h o u t i n - s i t u t e s t i n g , a n y p e r c o l a t i o n r a t e s o b t a i n e d f r o m l a b o r a t o r y t e s t i n g m u s t b e c a r e f u l l y s c r u t i n i z e d w i t h t h e s e f a c t o r s i n m i n d . 6 . 2 . 2 I n f l u e n c e of I n h e r e n t F i l l P r o p e r t i e s 6 . 2 . 2 . 1 G r a i n S h a p e A s p r e v i o u s l y d i s c u s s e d , t h e e f f e c t o f g r a i n s h a p e o n t h e p e r c o l a t i o n r a t e i s i n h e r e n t to t h e s o u r c e o f t h e f i l l . A s t h e s o u r c e of f i l l a t t h e M c L e l l a n M i n e i s a n a t u r a l l y o c c u r r i n g d e p o s i t o f g l a c i o - f l u v i a l m a t e r i a l i t i s a n t i c i p a t e d t h a t t h e g r a i n s a r e s u b - a n g u l a r to s u b - r o u n d e d . T h u s , t h e s p e c i f i c s u r f a c e of t h e g r a i n s ( S v ) s h o u l d b e n e a r o p t i m a l i n t e r m s of p e r c o l a t i o n . I f t h e f i l l i s w e l l g r a d e d , t h i s s h a p e w o u l d s t i l l l i k e l y r e s u l t i n a d e n s e p a c k i n g of t h e g r a i n s a n d a l o w e r v a l u e of p o r o s i t y . 6 . 2 . 2 . 2 G r a i n S i z e D i s t r i b u t i o n T w o p a r a m e t e r s of t h e g r a i n s i z e d i s t r i b u t i o n of t h e b a c k f i l l 132 a p p e a r to h a v e s i g n i f i c a n t a f f e c t s o n t h e p e r c o l a t i o n r a t e of t h e m a t e r i a l . T h e c o e f f i c i e n t o f u n i f o r m i t y , o r g e n e r a l s l o p e of t h e c u r v e , d e s c r i b e s t h e v a r i a t i o n i n t h e g r a i n s i z e s . T h e l o w e r t h e v a l u e o f C u , t h e m o r e u n i f o r m t h e g r a i n s i z e of t h e m a t e r i a l . T h e r e f o r e , as C u d e c r e a s e s t h e p o r o s i t y i n c r e a s e s , a s d o e s t h e p e r c o l a t i o n r a t e . H o w e v e r , t h i s e f f e c t d i m i n i s h e s a s t h e a m o u n t o f m a t e r i a l f i n e r t h a n 38 m i c r o n s i n c r e a s e s . I n a d e t a i l e d l i t e r a t u r e r e v i e w c o m p l e t e d a t t h e U n i v e r s i t y of B . C . t h e g r a i n s i z e d i s t r i b u t i o n c u r v e s a n d p e r c o l a t i o n r a t e s a t t a i n e d at v a r i o u s m i n e s w e r e i n v e s t i g a t e d . T h i s i n f o r m a t i o n i s s u m m a r i z e d i n F i g u r e 6 . 1 . 6 . 2 . 2 . 3 P o r o s i t y S o w e r s a n d S o w e r s ^ O s u g g e s t m a x i m u m a n d m i n i m u m v o i d r a t i o s of 0 . 7 5 a n d 0 . 3 5 f o r v e r y w e l l g r a d e d s a n d y g r a v e l . T h e v o i d r a t i o as p r e s e n t e d b y t h e m : e = V o i d V o l u m e S o l i d V o l u m e i s r e l a t e d to t h e p o r o s i t y ( n ) q u o t e d b y H e r g e t a n d D e K o r o m p a y n = V o i d V o l u m e T o t a l V o l u m e T h e r a n g e of 0 . 3 5 to 0 . 7 5 f o r t h e v o i d r a t i o t h e r e f o r e t r a n s l a t e s t o : 133 GRAIN SIZE (mm) Legend for G r a i n Size D i s t r i b u t i o n C u r v e s Permeability Symbol Mine, Location. Year (cm/h) Beaverlodge (1957) Single Value 8 Frood (1954) 20 Madsen Red Lake (1957) 12 Hardy & Fecunls, Falconbridge (1959) '1 Stnr Mine, Idaho (1966) 6 9 CSA Cobor, A u s t r a l i a (1973) 54 Mufutlrn, S. A f r i c a (1973) 41 Mount l s a , A u s t r a l i a (1973) 29 Homestake, U.S.A. (1973) 67 Fox, S h e r r i t t Cordon (1978) 17 Strnthconn, Falconbrldqo (1978) ^ Minimi, U.S.A. (J978) 26 V l h o n t l , F i n l a n d (19B5) 40 Pyhasnlml, Fi n l a n d (1983) 40 Vammala, Finl a n d (1983) 40 Gaspe, Noranda (1983) (Single value) India, R i v e r 5Bnd F i l l (1983) 56 India, Uranium tailings (1983) 56 Bor Copper, India (1983) 56 I homes (Coarse) (1983) 6 4 lhoma3 (Medium) ( 1983) fi4 1 homes (Fine) (1983) 6 4 I . C . C , India (1983) 59 Xiang-11 Mine, China (1933) 6 8 B r o k e n H i l l , S. A f r i c a (1983) 55 15.2 - 20.3 12.2 12.7 10.1 6.4 - 7.0 2.8 14.0 - 16.0 16.5 11.4 slow? • —JC-18.7 # 45 - 629 "More than adequate * " permeability" "—* 15 — -O—Q 10 O - O * In si t u mean F i g u r e 6 .1 H i s t o r i c a l G r a i n S i z e D i s t r i b u t i o n Curves f o r B a c k f i l l 134 n = e 1 + e n = 0 . 2 6 to 0 . 4 3 In p r a c t i s e t h e p o r o s i t y o f s i l t y s a n d p r o b a b l y r a n g e s f r o m 0 . 4 0 to 0 . 3 5 a f t e r b l a s t i n g h a s o c c u r r e d n e a r b y a n d t h e f i l l h a s b e e n s u b j e c t e d to m i n e t r a f f i c . T h u s , i f s a m p l e s of t h e m a t e r i a l a r e c o m p a c t e d b y v i b r a t i o n p r i o r to t h e c o m m e n c e m e n t of p e r c o l a t i o n r a t e t e s t s , t h e r e s u l t a n t p e r c o l a t i o n r a t e s w o u l d l i k e l y b e o n l y s l i g h t l y l o w e r t h a n t h e a c t u a l p e r c o l a t i o n r a t e s of t h e i n - p l a c e m a t e r i a l . 6 . 2 . 3 H i s t o r i c a l V a l u e s of P e r c o l a t i o n R a t e s T h e h i s t o r i c a l p e r c o l a t i o n r a t e s o b t a i n e d i n t h e l i t e r a t u r e r e v i e w a r e t a b u l a t e d i n T a b l e 6 .1 w i t h r e s p e c t to t h e m i n i n g m e t h o d ( c u t - a n d - f i l l v e r s u s o p e n s t o p i n g ) . B e c a u s e t h e b a c k f i l l m a t e r i a l i s p l a c e d i n b u l k p o u r s i n o p e n s t o p e s i t i s c r i t i c a l t h a t t h e p e r c o l a t i o n r a t e b e as h i g h as p o s s i b l e to p r e v e n t t h e b u i l d - u p of e x c e s s p o r e p r e s s u r e b e h i n d t h e b u l k h e a d s . In c u t - a n d - f i l l m i n i n g t h i s p h e n o m e n o n i s u n l i k e l y to o c c u r a n d t h e c r i t i c a l a s p e c t i s t h a t o f q u i c k l y d r a i n i n g e a c h l a y e r of f i l l as i t i s p l a c e d . M i n e s u s i n g t h e c u t - a n d - f i l l m i n i n g m e t h o d c a n u s e b a c k f i l l m a t e r i a l w i t h l o w e r p e r c o l a t i o n r a t e s t h a n m i n e s u s i n g t h e o p e n s t o p i n g m e t h o d . T h u s , t h e m i n i m u m p e r c o l a t i o n r a t e 135 T A B L E 6 . 1 S u m m a r y o f H i s t o r i c a l P e r c o l a t i o n R a t e s P e r c o l a t i o n 5.0 5.1-10.0 10.1-15.0 15.0 R a t e ( c m / h ) H o l l i n g e r C u t - a n d - F i l l F r o o d S t a r H a r d y B e a v e r l o d g e M i n e s C S A C o b a r F e c u n i s S t r a t h c o r n M u f u l i r a O p e n S t o p e s B r o k e n B r o k e n H i l l M a d s e n R e d L a k e H i l l B o r C o p p e r F o x G a s p e T h o m a s T h o m a s X i k u a n g s h a n F e n g h u a n g s h a n ( f i n e ) * ( c o a r s e ) F a n k o u ^ Q T h o m a s H u a n g s h a p i n g H u o n g t o u s h a n ( m e d ) U n c l a s s i f i e d T o n q l u s h a n M u d i n g L i n g s h a n H E-* 9 Z h a o y u a n D o n g x i a n g G J B C B A A T o t a l 12 8 9 8 * R e s u l t s o b t a i n e d f r o m t e s t s o n " t a i l i n g s - l i k e " m a t e r i a l 136 o f 10 c m / h r e c o m m e n d e d b y T h o m a s 6 5 a p p e a r s to b e c o n s e r v a t i v e as h e u s e s t h i s v a l u e i n a g e n e r a l s e n s e f o r b o t h m i n i n g m e t h o d s . L i u K e r e n a n d S u n K a i n i a n ^ 9 s u g g e s t a g e n e r a l m i n i m u m a c c e p t a b l e p e r c o l a t i o n r a t e o f 5 c m / h a n d g i v e a r a n g e of 4 . 0 to 5 . 7 c m / h f o r t h e F a n k o u M i n e . O n t h e b a s i s of t h e g r a i n s i z e d i s t r i b u t i o n c u r v e s a n d p e r c o l a t i o n r a t e s o b t a i n e d f r o m t h e l i t e r a t u r e r e v i e w a r a n g e i n t h e g r a i n s i z e d i s t r i b u t i o n c u r v e s f o r p r e f e r a b l e a n d a c c e p t a b l e b a c k f i l l m a t e r i a l h a s b e e n p r o d u c e d ( F i g u r e 6 . 2 ) . 0.001 GRAIN SIZE (mm) F i g u r e 6 . 2 - R e c o m m e n d e d R a n g e o f G r a i n S i z e D i s t r i b u t i o n f o r B a c k f i l l M a t e r i a l 137 6 . 2 . 4 D i s c u s s i o n A l t h o u g h no b o r r o w a r e a o f s u f f i c i e n t q u a n t i t y h a s b e e n i d e n t i f i e d as y e t , a c o m m i t t m e n t h a s b e e n m a d e to u s e g l a c i o f l u v i a l m a t e r i a l f o r b a c k f i l l . T h e i n i t i a l t e s t r e s u l t s of g l a c i o f l u v i a l m a t e r i a l a t a n d a r o u n d t h e M c L e l l a n S i t e i n d i c a t e t h a t t h e m a t e r i a l w i l l l i k e l y c o n s i s t o f s u b - a n g u l a r to s u b - r o u n d e d s i l t y s a n d w i t h some g r a v e l to s a n d y s o i l . It t h e r e f o r e a p p e a r s l i k e l y t h a t a b a c k f i l l m a t e r i a l w i l l b e p r o d u c e d , t h r o u g h b l e n d i n g , t h a t h a s t h e f o l l o w i n g r a n g e of p a r a m e t e r s : C u = 4 to 6 D l Q = 0 . 0 1 5 mm to 0 . 0 5 mm K = 5 to 10 c m / h r 138 6 . 3 B E A R I N G C A P A C I T Y 6 . 3 . 1 G e n e r a l G i v e n t h e d e s i g n r a t e of p r o d u c t i o n a t t h e M c L e l l a n M i n e a n d t h e g e o m e t r y o f t h e c u t - a n d - f i l l s t o p e s , t h e i n i t a l s t r e n g t h r e q u i r e m e n t s o f t h e h y d r a u l i c f i l l a r e : 1 ) S u p p o r t w o r k e r s w i t h i n 12 h o u r s 2 ) S u p p o r t b l a s t e d m u c k w i t h i n 2 d a y s 3 ) In c o n j u n c t i o n w i t h a 0 . 6 m e t r e t o p p i n g of m u c k , s u p p o r t v e h i c l e s w i t h i n 2 1 /2 d a y s 4 ) S u p p o r t m i n e v e h i c l e s w i t h o u t m u c k w i t h i n 2 w e e k s In o r d e r to e s t i m a t e t h e b e a r i n g c a p a c i t y o f t h e b a c k f i l l u n d e r t h e l o a d of t h e v e h i c l e s t h e f o l l o w i n g d a t a m u s t b e k n o w n : 1) b e a r i n g p r e s s u r e ( t i r e p r e s s u r e ) q Q 2) d i a m e t e r o f c o n t a c t a r e a ( B ) 3 ) u n i t w e i g h t o f s o i l ( Y ) 4 ) a n g l e o f i n t e r n a l f r i c t i o n o f s o i l (0) 5) c o h e s i o n of s o i l ( c ) 6 ) c a p i l l a r y t e n s i o n ( u ) 139 6 . 3 . 2 E s t i m a t e s of I n p u t P a r a m e t e r s 6 . 3 . 2 . 1 B e a r i n g P r e s s u r e a n d C o n t a c t A r e a A t t h e M c L e l l a n M i n e i t i s p l a n n e d to u s e s c o o p t r a m s w i t h 1 7 . 5 X 2 5 20 p l y t i r e s w i t h a w o r k i n g p r e s s u r e o f 4 1 3 . 7 k P a to h a u l m u c k to t h e o r e p a s s e s . Wi th a f u l l y l o a d e d m a x i m u m m a s s o f 1 5 , 1 8 5 k g o n t h e f r o n t t i r e s a n d 4 , 9 2 5 k g 6 6 on t h e b a c k t i r e s , t h e c o n t a c t a r e a b e t w e e n t h e f i l l a n d t h e t i r e s w i l l b e 1800 c m 2 f o r t h e f r o n t t i r e s a n d 5 8 3 . 5 c m 2 f o r t h e b a c k t i r e s . If a f l a t , c i r c u l a r c o n t a c t a r e a i s a s s u m e d t h e d i a m e t e r of t h e c o n t a c t a r e a w i l l b e 4 7 . 8 8 c m a n d 2 7 . 2 8 c m f o r t h e f r o n t a n d b a c k t i r e s . 6 . 3 . 2 . 2 U n i t W e i g h t ( D e n s i t y ) a n d i n t e r n a l A n g l e of F r i c t i o n O n t h e b a s i s of p r e l i m i n a r y o b s e r v a t i o n s , t h e b l e n d e d f i l l m a t e r i a l w i l l l i k e l y b e a s u b a n g u l a r to s u b r o u n d e d s i l t y s a n d . F r o m T a b l e 6 . 2 i t c a n b e e s t i m a t e d t h a t f o r a w e l l - g r a d e d s i l t y s a n d t h e m a x i m u m a n d m i n i m u m v o i d r a t i o s w o u l d b e 0 . 7 0 a n d 0 . 3 5 r e s p e c t i v e l y . In a d d i t i o n t h e s a t u r a t e d u n i t w e i g h t w o u l d b e e s t i m a t e d at 123 to 139 l b / f t 3 (1900 K g / m ) to 22000 k g / m 3 f o r m a t e r i a l c o m p o s e d c h i e f l y of q u a r t z g r a i n s . T a b l e 6 . 3 e s t i m a t e s t h e a n g l e o f i n t e r n a l f r i c t i o n f o r l o o s e to 140 d e n s e q u a r t z s a n d s . T h u s , f o r t h e b a c k f i l l m a t e r i a l a t M c L e l l a n M i n e i t i s e s t i m a t e d t h a t t h e a n g l e o f i n t e r n a l f r i c t i o n w i l l r a n g e f r o m 3 5 ° to 4 5 ° . I n c o m p a r i s o n B . G . R i c h a r d s 5 ^ q u o t e d d r y d e n s i t i e s of 1600 t o 1870 K g / c m . 3 a n c | a n a n g l e o f i n t e r n a l f r i c t i o n r a n g i n g f r o m 3 7 ° t o 5 0 ° . In a d d i t i o n M a t h e w s e t . a l . (1975P2 r e p o r t e d a n i n t e r n a l a n g l e o f f r i c t i o n v a r y i n g f r o m 3 2 ° f o r u n c l a s s i f i e d s e r i c i t i c t a i l i n g s to 3 9 ° f o r d e s l i m e d w a s t e r o c k w i t h a h i g h c o n t e n t o f m i c a c e o u s f i n e s . T h u s , i t i s e s t i m a t e d t h a t t h e v a l u e s f o r t h e f i l l m a t e r i a l w o u l d r a n g e f r o m O = 1600 to 2200 K g / m 3 a n d (f> - 3 5 ° to 4 5 ° . I t i s l i k e l y t h a t t h e c o h e s i o n o f t h e f i l l w o u l d b e n e g l i g i b l e . 6 . 3 . 2 . 3 C a p i l l a r i t y T h e m a x i m u m c a p i l l a r y t e n s i o n a n d c r i t i c a l c a p i l l a r y h e i g h t c a n b e e s t i m a t e d f o r t h e b a c k f i l l m a t e r i a l g i v e n a s p e c i f i c g r a i n s i z e d i s t r i b u t i o n ^ 0 . B a s e d u p o n t h e l i k e l y b l e n d o f m a t e r i a l to b e u s e d a t t h e M c L e l l a n M i n e a n d t h e g r a i n s i z e d i s t r i b u t i o n c u r v e s f o r f i l l s u s e d at o t h e r m i n e s i t i s e s t i m a t e d t h a t : 141 T A B L E 6 . 2 T y p i c a l V o i d R a t i o s a n d W e i g h t s of S i n g l e G r a i n e d S t r u c t u r e s ( A f t e r S o w e r s a n d S o w e r s ) b U S o i l D e s c r i p t i o n V o i d R a t i o M a x i m u m M i n i m u m U n i t W e i g h t ( l b / c u f t ) M i n i m u m a x i m u m U n i f o r m s u b a n g u l a r 0 . 8 5 s a n d W e l l - g r a d e d s u b - 0 . 7 0 a n g u l a r s a n d V e r y w e l l g r a d e d 0 . 6 5 s i l t y s a n d y g r a v e M i c a c e o u s s a n d a n d 1 .25 s i l t 0 . 5 0 0 . 3 5 0 . 2 5 0 . 8 0 118 ( s a t ) 89 ( d r y ) 123 ( s a t ) 97 ( s a t ) 125 ( s a t ) 100 ( d r y ) 110 ( s a t ) 75 ( d r y ) 131 ( s a t ) 110 ( d r y ) 139 ( d r y ) 122 ( d r y ) 145 ( s a t ) 132 ( d r y ) 122 ( s a t ) 94 ( d r y ) T A B L E 6 . 3 A n g l e o f I n t e r n a l F r i c t i o n of C o h e s i o n l e s s S o i l s  C o m p o s e d L a r g e l y of Q u a r t z ( A f t e r S o w e r s a n d S o w e r s ) 6 0 D e s c r i p t i o n A n g l e of I n t e r n a l F r i c t i o n D r l e s s t h a n 20 D r o v e r 70 R o u n d e d , u n i f o r m 29 35 R o u n d e d , w e l l - g r a d e d 32 38 A n g u l a r , u n i f o r m 35 43 A n g u l a r , w e l l - g r a d e d 37 45 D 1 0 = 0 . 0 1 5 mm to 0 . 0 5 mm G i v e n t h a t : U m a x = 4 T o d a n d h c = 4 T o * w d w h e r e U m a x = m a x i m u m n e g a t i v e p o r e p r e s s u r e h c = m a x i m u m c a p i l l a r y r i s e T o = - 0 . 0 7 5 g / c m = s u r f a c e t e n s i o n of w a t e r d = d i a m e t e r o f p o r e s p a c e = D J Q a n d 5 a/w = u n i t w t . o f w a t e r t h e s e v a l u e s c a n b e e s t i m a t e d to b e i n t h e r a n g e U m a x = 2 9 - 1 9 k P a t o 9 7 « 2 8 k P a h c = 2 . 9 8 m to 9 . 9 2 m T h e r e f o r e t h e c a p i l l a r y t e n s i o n c a n b e e x p r e s s e d as u = u m a v h w h e r e h = d e p t h f r o m s u r f a c e of f i l l to w a t e r t a b l e . a n d h < he w h e n h ^ h c U = U m a x I f t h e p e r c o l a t i o n r a t e k i s k n o w n , t h e n h = k t 143 w h e r e t = t ime e l a p s e d s i n c e f i l l i n g c o m p l e t e d . A s s u m i n g a p e r c o l a t i o n r a t e of 5 c m / h r t h e c a p i l l a r y t e n s i o n a t t h e c r i t i c a l d e s i g n e v e n t s c a n b e e s t i m a t e d as g i v e n i n T a b l e 6 . 4 . T A B L E 6 . 4 E s t i m a t e d C a p i l l a r y T e n s i o n E v e n t T i m e ( h r s ) U ( k P a ) D 1 0 = D 1 0 0 . 0 5 m m 0 . 0 1 5 mm S u p p o r t w o r k e r s 12 5 . 8 8 k P a 5 . 8 8 k P a S u p p o r t b l a s t e d m u c k 48 2 3 . 5 1 k P a 2 3 . 5 1 k P a S u p p o r t v e h i c l e s 60 2 9 . 1 9 k P a 2 9 . 4 1 k P a 0 . 6 m b l a s t e d m u c k S u p p o r t v e h i c l e s 672 0 0 6 . 3 . 3 E s t i m a t e s of B e a r i n g C a p a c i t y 6 . 3 . 3 . 1 I n f l u e n c e of C a p i l l a r i t y T h e b e a r i n g c a p a c i t y d u e to t h e n e g a t i v e p o r e p r e s s u r e c a n 144 b e c a l c u l a t e d f r o m M o h r - C o u l o m b t h e o r y a n d t h e e s t i m a t e s g i v e n i n T a b l e 6 . 4 as f o l l o w s : 03 = - U s = 0 1 - 0 3 C o s e 2 0} = 0 3 t a n 2 ( 4 5 + ft?) F r o m T e r z a g h i & P e c k [ ^ 3 ] q f = 1.2 c N c = 1 .2 s N c T h e r e s u l t a n t b e a r i n g c a p a c i t y e s t i m a t e d f o r e a c h c r i t i c a l e v e n t a n d t h e m i n i m u m a n d m a x i m u m v a l u e of D^g a n d i n t e r n a l a n g l e o f f r i c t i o n a r e s u m m a r i z e d i n T a b l e 5 . 5 . 145 T A B L E 6 . 5 E s t i m a t e d B e a r i n g C a p a c i t y D u e T o N e g a t i v e P o r e P r e s s u r e ( k P a ) ^ = 3 5 ° jef=45 o E v e n t T i m e D 1 0 = D 1 0 = D 1 0 = D 1 0 = ( h r s ) 0 . 0 5 m m 0 . 0 1 5 m m 0 . 0 5 m m 0 . 0 1 5 m m S u p p o r t 12 40 40 56 56 w o r k e r s S u p p o r t 48 160 248 248 248 b l a s t e d m u c k S u p p o r t 60 198 200 307 310 V e h i c l e s o n C . 6 m b l a s t e d m u c k S u p p o r t 672 0 0 0 0 v e h i c l e s 146 6 . 3 . 3 . 2 I n f l u e n c e of S o i l W e i g h t a n d F o u n d a t i o n W i d t h T h e b e a r i n g c a p a c i t y o f s o i l u n d e r a c o n t i n u o u s f o o t i n g d u e t o t h e s o i l w e i g h t a n d t h e f o u n d a t i o n w i d t h c a n b e c a l c u l a t e d b y t h e T e r z a g h i - M e y e r h o f e q u a t i o n ^ : q = X_B_ 2 w h e r e q = b e a r i n g c a p a c i t y y = u n i t w e i g h t o f s o i l B = f o o t i n g w i d t h , f o r a s q u a r e f o o t i n g = b e a r i n g - c a p a c i t y f a c t o r f r o m M e y e r h o f c u r v e s d e p e n d e n t o n t h e a n g l e o f i n t e r n a l f r i c t i o n I n t h e c a s e o f a t i r e o n s o i l , t h e f o o t i n g w i d t h i s e q u i v a l e n t t o t h e d i a m e t e r o f t h e c i r c u l a r c o n t a c t a r e a a n d a s h a p e f a c t o r o f 0 . 7 m u s t b e i n t r o d u c e d . A s s u m i n g a b a c k f i l l d e n s i t y r a n g i n g f r o m 1 6 0 0 kg / n r v * t o 2200 k g / m ^ a n d a n I n t e r n a l f r i c t i o n a n g l e r a n g i n g f r o m 3 5 ° to 4 5 ° a r a n g e f o r t h e b e a r i n g c a p a c i t y o f t h e f i l l w a s e s t i m a t e d f o r t h e f r o n t a n d b a c k t i r e s a s s p e c i f i e d i n S e c t i o n 6 . 2 . 2 . 1 . T h e s e r e s u l t s a r e s u m m a r i z e d i n T a b l e 6 . 6 . 147 T A B L E 6 . 6 E s t i m a t e d B e a r i n g C a p a c i t y D u e to S o i l W e i g h t  F o r S c o o p t r a m s D e n s i t y F r i c t i o n A n g l e B e a r i n g C a p a c i t y ( k g / m 3 ) ( ° ) ( k P a ) F r o n t t i r e s B a c k t i r e s 1600 35 105 60 40 263 150 45 657 374 1800 35 118 67 40 296 168 45 739 421 2000 35 131 75 40 329 187 45 821 468 2200 35 142 82 40 361 206 45 904 515 148 6 . 3 . 4 D y n a m i c A n a l y s i s of I m p a c t of B l a s t e d M u c k o n S u r f a c e  of B a c k f i l l 6 . 3 . 4 . 1 A s s u m p t i o n s I n o r d e r to c o m p l e t e a d y n a m i c a n a l y s i s of t h e i m p a c t of b l a s t e d m u c k o n t h e s u r f a c e of t h e b a c k f i l l a n u m b e r of a s s u m p t i o n s m u s t f i r s t b e m a d e to s i m p l i f y t h e p r o b l e m . T h e m u c k as a w h o l e c a n n o t b e a n a l y z e d d y n a m i c a l l y d u e to t h e v a r i a b l e s i z e , s h a p e a n d d i r e c t i o n o f t r a v e l o f t h e i n d i v i d u a l b l o c k s . T h e a n a l y s i s m u s t t h e r e f o r e a s s u m e : 1) T h a t i n d i v i d u a l b l o c k s of o r e c a n b e a n a l y z e d i n d e p e n d e n t l y 2 ) T h a t t h e d i r e c t i o n o f t r a v e l o f e a c h b l o c k i s v e r t i c a l , a n d 3) T h a t t h e i n d i v i d u a l b l o c k s a r e c u b e s . T h e s e a s s u m p t i o n s e n s u r e t h a t t h e a n a l y s i s w i l l b e c o n s e r v a t i v e b e c a u s e t h e i n t e r f e r e n c e of i n d i v i d u a l b l o c k s of o r e w i t h o n e a n o t h e r w o u l d l i k e l y r e d u c e t h e i m p a c t m o m e n t u m of t h e b l o c k s . In a d d i t i o n t h e d o w n w a r d c o m p o n e n t o f t h e v e l o c i t y o f t h e b l o c k s w o u l d b e m u c h l e s s d u e to o b l i q u e a n g l e s of e n t r y i n t o t h e b a c k f i l l . S i m p l i f y i n g a s s u m p t i o n s a l s o h a v e to b e m a d e w i t h r e g a r d to 149 t h e f i l l . F i r s t t h e s o i l m u s t b e a s s u m e d to r e a c t to t h e i m p a c t a s a p e r f e c t l y p l a s t i c , l i n e a r s p r i n g . A s t h e b a c k f i l l i s a n o n - l i n e a r e l a s t i c m a t e r i a l , t h i s a l s o l e a d s to a c o n s e r v a t i v e e s t i m a t e of t h e m u c k p e n e t r a t i o n . In a d d i t i o n , i t m u s t b e a s s u m e d t h a t t h e r e i s n o f r i c t i o n a l r e s i s t a n c e p r o v i d e d b y t h e f i l l to t h e e n t r y o f t h e b l o c k s o f o r e . A g a i n , t h i s l e a d s to a c o n s e r v a t i v e e s t i m a t e of t h e m u c k p e n e t r a t i o n i n t o t h e f i l l . 6 . 3 . 4 . 2 D y n a m i c A n a l y s i s A s t h e c o n s e r v a t i o n of e n e r g y m u s t a p p l y to t h e i m p a c t o f c u b e s of o r e w i t h t h e s u r f a c e of t h e b a c k f i l l , t h e k i n e t i c e n e r g y o f t h e m o v i n g m a s s o f o r e m u s t b e e q u a l to t h e w o r k d o n e b y c o m p r e s s i n g t h e s o i l " s p r i n g " . T h e r e f o r e f o r a l i n e a r l y p l a s t i c s p r i n g : k 1 = 1/2 mv2 w h e r e k = s t i f f n e s s of s p r i n g 1 = c o m p r e s s i o n of s p r i n g m = m a s s of b l o c k o f o r e a n d , v = v e l o c i t y of b l o c k . T h e s t i f f n e s s o f t h e s o i l " s p r i n g " c a n b e e q u a t e d to t h e Y o u n g ' s M o d u l u s of t h e s o i l as f o l l o w s : 150 k = F 1 w h e r e F = f o r c e a p p l i e d to t h e s p r i n g a n d E = cr € b u t cr = F A w h e r e A = c o n t a c t a r e a a n d £ = 1 L w h e r e L = t h i c k n e s s o f m a t e r i a l ( o r l e n g t h of s p r i n g ) t h e r e f o r e k = E A L a n d E A . 1 = 1/2 m v 2 L t h e r e f o r e 1 = L m v 2 2EA A s t h e t h i c k n e s s of t h e b a c k f i l l c a n b e t a k e n as t h e t h i c k n e s s of o n e f i l l l a y e r o r a s t h e t o t a l t h i c k n e s s of t h e f i l l i n t h e s t o p e , a n o t h e r s i m p l i f y i n g a s s u m p t i o n m u s t b e m a d e . It i s w e l l k n o w n t h a t t h e s t r e s s e s u n d e r a f o o t i n g d u e to a s u r f a c e l o a d a r e d i s t r i b u t e d t h r o u g h o u t t h e s o i l m a s s . If t h e i m p a c t of t h e m u c k w i t h t h e s o i l m a s s i s d i s t r i b u t e d a c c o r d i n g to B o u s s i n e s q T h e o r y ( F i g u r e 6.3) t h e n t h e i n c r e a s e i n s t r e s s i s l e s s t h a n 10% o f t h e s u r f a c e s t r e s s at a d e p t h of t w o t imes t h e w i d t h of t h e f o o t i n g . F i g u r e 6 . 3 S t r e s s D i s t r i b u t i o n U n d e r a F o o t i n g a f t e r B o u s s i n e s q [ 6 0 ] 152 I f i t i s a s s u m e d t h a t t h e t h i c k n e s s of t h e f i l l a f f e c t e d b y t h e i m p a c t i s e q u i v a l e n t to two t i m e s t h e d i m e n s i o n of t h e c u b e of m u c k , l i t t l e e r r o r w i l l b e i n t r o d u c e d . In a d d i t i o n , i f i t i s a l s o a s s u m e d t h a t t h e i n c r e a s e i n s t r e s s i n t h e f i l l i s c o n s t a n t to t h a t d e p t h , a c o n s e r v a t i v e e s t i m a t e of t h e p e n e t r a t i o n of t h e c u b e of m u c k i n t o t h e b a c k f i l l w i l l b e o b t a i n e d . A l l o f t h e p a r a m e t e r s i n e q u a t i o n (1) c a n n o w b e e s t i m a t e d . L = 2B w h e r e B = t h e d i m e n s i o n of t h e c u b e , m = oV w h e r e o = d e n s i t y of m u c k = 2960 k g / m ^ V = v o l u m e o f c u b e = B 3 E = 6 . 9 M P a ( S e c t i o n 4 . 3 ) A = c o n t a c t a r e a = B 2 v = v e l o c i t y of c u b e of o r e f r o m b l a s t = 15 to 30 m / s e c 3 i a n d e q u a t i o n (1) r e d u c e s t o : 1 = ( . 0 2 s e c / m ) B v 2 T h e e s t i m a t e d p e n e t r a t i o n i n t o t h e b a c k f i l l b y v a r i o u s s i z e d c u b e s of m u c k i s g i v e n i n T a b l e 6 . 7 . 153 T A B L E 6 . 7 E s t i m a t e d P e n e t r a t i o n of M u c k I n t o t h e B a c k f i l l C u b e S i z e (m) P e n e t r a t i o n (m) v = 1 5 m / s e c v = 3 0 m / s e c . 0 5 .02 .03 . 1 5 .04 .09 . 30 .09 .18 . 60 .18 .36 6 . 3 . 5 D i s c u s s i o n D u e to t h e d i f f e r e n c e i n t h e s t r e s s e s t h a t t h e b a c k f i l l w i l l b e s u b j e c t e d to a t d i f f e r e n t t i m e s d u r i n g o n e m i n i n g c y c l e , t h e e s t i m a t e s o f b e a r i n g c a p a c i t y p r o v i d e d f o r men a n d e q u i p m e n t w i l l b e d i s c u s s e d i n r e l a t i o n to t h e f o u r r e q u i r e m e n t s g i v e n i n S e c t i o n 6 . 3 . 1 . 6 . 3 . 5 . 1 S u p p o r t W o r k e r s W i t h i n 12 H o u r s A s s u m i n g a m a s s o f 90 k i l o g r a m s f o r t h e a v e r a g e m i n e r a n d a 154 c o n t a c t a r e a of 10 c m b y 30 c m f o r o n e f o o t , t h e c o n t a c t p r e s s u r e i s c a l c u l a t e d to b e a p p r o x i m a t e l y 30 k P a . T h e b e a r i n g c a p a c i t y of t h i s f o u n d a t i o n i s c a l c u l a t e d i n a m a n n e r s i m i l a r to t h a t f o r t h e t i r e s , e x c e p t a c o r r e c t i o n f a c t o r o f 0 . 9 2 s h o u l d b e u s e d f o r a r e c t a n g u l a r " f o o t i n g " . T h u s , t h e b e a r i n g c a p a c i t y o f t h e s o i l d u e to t h e s o i l w e i g h t i s c a l c u l a t e d to b e a m i n i m u m o f 29 k P a a n d t h e c a p a c i t y d u e to n e g a t i v e p o r e p r e s s u r e a f t e r 12 h o u r s i s 40 k P a . T h e s e v a l u e s a r e b a s e d u p o n a s o i l d e n s i t y of 1600 k g / m 3 a n d a n i n t e r n a l a n g l e of f r i c t i o n of 3 5 ° , c o r r e s p o n d i n g to t h e l o o s e c o n d i t i o n of t h e b a c k f i l l j u s t a f t e r p l a c e m e n t . 6 . 3 . 5 . 2 S u p p o r t M u c k A f t e r 2 D a y s A s s h o w n i n T a b l e 6 . 8 , a c o n s e r v a t i v e e s t i m a t e of t h e p e n e t r a t i o n of t h e m u c k i n t o t h e b a c k f i l l y i e l d s a m a x i m u m p e n e t r a t i o n of 0 . 3 6 m f o r a 0 . 6 m c u b e of m u c k . T h e r e f o r e , i f a l l o f t h e s i m p l i f y i n g a s s u m p t i o n s a r e t a k e n i n t o a c c o u n t , i t a p p e a r s u n l i k e l y t h a t a n y s i g n i f i c a n t p o r t i o n of t h e m u c k w o u l d p e n e t r a t e m o r e t h a n 0 .1 m i n t o t h e b a c k f i l l m a t e r i a l . T h e b e a r i n g c a p a c i t y of t h e b a c k f i l l i s c a l c u l a t e d i n t h e same m a n n e r a s f o r t h e t i r e s w i t h a c o r r e c t i o n f a c t o r of 0 . 8 5 f o r a s q u a r e f o o t i n g . E s t i m a t e s o f t h e b e a r i n g c a p a c i t y f o r v a r i o u s s i z e s of c u b e s a r e g i v e n i n T a b l e 6 . 8 f o r b a c k f i l l w i t h a 155 d e n s i t y of 1600 k g / n v a n d a n i n t e r n a l a n g l e of f r i c t i o n of 3 5 ° . T A B L E 6 . 8 E s t i m a t e d B e a r i n g C a p a c i t y of F i l l F o r O r e D u e T o S o i l W e i g h t S i z e of C u b e B e a r i n g C a p a c i t y ( k P a ) 15 c m 13 15 c m 40 30 c m 80 60 c m 160 In a d d i t i o n t h e e f f e c t o f n e g a t i v e p o r e p r e s s u r e w o u l d p r o v i d e a n a d d i t i o n a l e s t i m a t e d b e a r i n g c a p a c i t y of a p p r o x i m a t e l y 160 k P a . 6 . 3 . 5 . 3 S u p p o r t E q u i p m e n t W i t h i n 2 . 5 D a y s w i t h 0 . 6 m C o v e r of  M u c k W i t h i n 2 . 5 d a y s o r 60 h o u r s of f i l l i n g , m i n i n g e q u i p m e n t s u c h as t h e W a g n e r S T - 3 1/2 S c o o p t r a m s w i l l b e o p e r a t i n g on a 0 . 6 m e t r e l a y e r of b l a s t e d m u c k l e f t on t o p of t h e b a c k f i l l . T h e e f f e c t of t h e b l a s t e d m u c k i s to d i s t r i b u t e t h e a p p l i e d l o a d 156 on t h e m u c k o v e r an i n c r e a s e d a r e a o n t h e b a c k f i l l . O n e of t h e f o r m u l a e mos t w i d e l y u s e d to c a l c u l a t e t h e i n c r e a s e i n s t r e s s a t a d e p t h b e l o w t h e s u r f a c e i s t h a t of B o u s s i n e s q . H e a s s u m e s a h o m o g e n e o u s , e l a s t i c , i s o t r o p i c m a s s e x t e n d i n g i n f i n i t e l y i n a l l d i r e c t i o n s b e l o w a l e v e l s u r f a c e . A l t h o u g h t h e s t o p e w i d t h at t h e M c L e l l a n M i n e i s no t i n f i n i t e , i t i s m u c h g r e a t e r t h a n t h e d i a m e t e r of t h e f o u n d a t i o n w i d t h . T h u s l i t t l e e r r o r w o u l d b e i n t r o d u c e d b y t h e s e a s s u m p t i o n s . T h u s , t h e p e a k s t r e s s u n d e r a t i r e a t d e p t h of 0 .6 m m a y b e e s t i m a t e d f r o m F i g u r e 6 . 3 to b e a p p r o x i m a t e l y 0 . 3 q o r 125 k P a f o r t h e f r o n t t i r e s a n d 0 .1 q o r 42 k P a f o r t h e b a c k t i r e s . T h e b e a r i n g c a p a c i t y e s t i m a t e d f o r a d e n s i t y of 1600 k g / m 3 a n d a n i n t e r n a l a n g l e of f r i c t i o n of 3 5 ° a r e 105 k P a f o r s o i l w e i g h t a n d 20 k P a f o r n e g a t i v e p o r e p r e s s u r e f o r t h e f r o n t t i r e s a n d 60 k P a a n d 29 k P a f o r t h e b a c k t i r e s . 6 . 3 . 5 . 4 S u p p o r t E q u i p m e n t W i t h i n T w o W e e k s W h e n t h e c l e a n - u p of t h e 0 . 6 m of m u c k c o m m e n c e s w i t h t h e W a g n e r S T - 3 1/2 s c o o p t r a m s t h e b a c k f i l l m a t e r i a l h a s b e e n s u b j e c t e d to c o m p a c t i o n b y v i b r a t i o n s f r o m b l a s t i n g a n d b y m i n e t r a f f i c . T h u s , b o t h t h e i n t e r n a l a n g l e of f r i c t i o n a n d t h e 157 d e n s i t y w i l l l i k e l y b e i n t h e u p p e r h a l f o f t h e r a n g e of v a l u e s g i v e n f o r t h e f i l l m a t e r i a l . T h i s w o u l d m a r k e d l y i n c r e a s e t h e b e a r i n g c a p a c i t y of t h e f i l l d u e to t h e s o i l w e i g h t . A s s u m i n g a n i n - p l a c e d e n s i t y of 2 , 0 0 0 k g / m ^ a n d a n i n t e r n a l a n g l e of f r i c t i o n of 4 2 ° t h e b e a r i n g c a p a c i t y of t h e s o i l w o u l d b e 490 k P a f o r t h e f r o n t t i r e s a n d 280 k P a f o r t h e b a c k t i r e s . If t h e t i r e p r e s s u r e i n t h e b a c k t i r e s w a s r e d u c e d to 345 k P a (50 p s i ) t h e b e a r i n g c a p a c i t y f o r t h e s e t i r e s w o u l d i n c r e a s e to 307 k P a . T h u s a n y c o n t r i b u t i o n to t h e b e a r i n g c a p a c i t y b y c o h e s i o n o r n e g a t i v e p o r e p r e s s u r e w o u l d p r o v i d e a s u f f i c i e n t b e a r i n g c a p a c i t y f o r t h e b a c k f i l l . 158 6 . 4 S U P P O R T C A P A B I L I T Y Q F F I L L 6 . 4 . 1 G e n e r a l T h e n u m e r i c a l a n a l y s i s of t h e c u t - a n d - f i l l s t o p e s at t h e M c L e l l a n M i n e i n v o l v e s t h e u s e of a f i n i t e e l e m e n t m e t h o d to m o d e l t h e a c t u a l e x c a v a t i o n a n d b a c k f i l l i n g s e q u e n c e of t h e f u t u r e m i n i n g o p e r a t i o n s . T h r e e c o n s e c u t i v e c u t s a r e " e x c a v a t e d " f r o m t h e s t o p e b y r e d u c i n g t h e s t i f f n e s s of t h o s e e l e m e n t s to n e a r z e r o a n d an e l a s t i c a n a l y s i s i s t h e n c o m p l e t e d . In t h e n e x t s t e p t h r e e a d d i t i o n a l c u t s a r e " e x c a v a t e d " , t h e f i r s t t h r e e a r e " b a c k f i l l e d " i n a s i m i l a r m a n n e r a n d a n e l a s t i c a n a l y s i s i s a g a i n c o m p l e t e d u s i n g t h e r e s u l t s of t h e f i r s t a n a l y s i s . T h i s p r o c e s s i s r e p e a t e d u n t i l t h e " m i n i n g " o f t h e s t o p e s i s c o m p l e t e d . B e c a u s e l i t t l e i s k n o w n a b o u t t h e b a c k f i l l m a t e r i a l at t h i s t ime n o n - l i n e a r a n a l y s i s of t h e b a c k f i l l c a n n o t b e j u s t i f i e d . H e n c e , t h e b a c k f i l l m a t e r i a l i s a s s u m e d to b e l i n e a r l y e l a s t i c a n d t h e m a t e r i a l p r o p e r t i e s of t h e b a c k f i l l r e q u i r e d f o r t h e a n a l y s i s a r e t h e Y o u n g ' s M o d u l u s , P o i s s o n ' s R a t i o a n d b u l k d e n s i t y . T h e f i l l i s k n o w n to b e a n o n l i n e a r e l a s t i c m a t e r i a l d u e t o : 1) I n c r e a s e d l o a d i n g of f i l l m a t e r i a l w i t h s u b s e q u e n t l i f t s 159 2) D e n s i f i c a t i o n d u e to d e w a t e r i n g a n d 3) I n c r e a s e d s t r e s s d u e to s t o p e c l o s u r e . F o r t h i s r e a s o n , a s e n s i t i v i t y a n a l y s i s n e e d s to b e u n d e r -t a k e n o n t h e e f f e c t of a l t e r i n g t h e s e t h r e e p a r a m e t e r s o n t h e s t o p e a n d p i l l a r s t a b i l i t y . 6 . 4 . 2 H i s t o r i c a l D a t a In o r d e r to d e t e r m i n e a p r o p e r r a n g e of v a l u e s f o r t h e t h r e e m a t e r i a l p r o p e r t y p a r a m e t e r s , a d e t a i l e d l i t e r a t u r e r e v i e w w a s c o m p l e t e d . T h e d a t a o b t a i n e d f r o m t h i s r e v i e w i s s u m m a r i z e d i n T a b l e 6 . 9 . 6 . 4 . 3 D i s c u s s i o n A s c a n b e s e e n , t h e d a t a o b t a i n e d v a r i e s m a r k e d l y f r o m s o u r c e to s o u r c e a n d e v e n f r o m t e s t to t e s t . T h i s v a r i a n c e i s to b e e x p e c t e d d u e to d i f f e r e n c e s i n p l a c e m e n t t e c h n i q u e s , g r a i n s i z e d i s t r i b u t i o n , l i t h o l o g y of b a c k f i l l m a t e r i a l a n d t ime of t e s t i n g r e l a t i v e to t h e e m p l a c e m e n t of b a c k f i l l m a t e r i a l . In a d d i t i o n , some of t h e v a l u e s a r e o n l y a s s u m e d v a l u e s f o r m o d e l l i n g p u r p o s e s . H o w e v e r , i t i s k n o w n t h a t t h e b a c k f i l l m a t e r i a l to b e u s e d at t h e M c L e l l a n M i n e i s to b e o b t a i n e d f r o m a g l a c i o f l u v i a l d e p o s i t 160 of s i l t y s a n d a n d g r a v e l to b e b l e n d e d p r i o r to e m p l a c e m e n t . T h u s , i t i s l i k e l y t h a t : 1) B o t h g l a c i a l a n d f l u v i a l a c t i o n w o r k e d to r e m o v e t h e s o f t e r , g r a i n s w i t h l o w e r m o d u l u s of e l a s t i c i t y . 2) T h e s e same m e c h a n i c a l a c t i o n s h a v e r e s u l t e d i n s u b - a n g u l a r to s u b - r o u n d e d g r a i n s . O n l y a m i n i m a l a m o u n t of p l a t y g r a i n s w i l l e x i s t i n t h e f i l l . 3 ) T h e b l e n d i n g of d i f f e r e n t m a t e r i a l s s h o u l d e n s u r e a c o e f f i c i e n t o f u n i f o r m i t y b e t w e e n f o u r a n d s e v e n . T h e r e f o r e i t i s a s s u m e d t h a t t h i s m a t e r i a l w o u l d b e n e a r o p t i m a l f o r m a x i m u m v a l u e s of Y o u n g ' s M o d u l u s a n d d e n s i t y . In a d d i t i o n , i f t h e m a t e r i a l i s p l a c e d w i t h a h i g h p u l p d e n s i t y , 65%-75% d r y s o l i d s b y w e i g h t , i t s h o u l d c o m p a c t r e a d i l y d u r i n g e m p l a c e m e n t a n d l a t e r d u e to v i b r a t i o n f r o m b l a s t i n g a n d m i n i n g e q u i p m e n t . If t h e s e f a c t o r s a r e c o n s i d e r e d w i t h r e s p e c t to t h e m o d e l l i n g p r o c e d u r e , w h e r e b y 3 l i f t s a r e " e x c a v a t e d " a n d " f i l l e d " at e a c h s t a g e , i t i s e x p e c t e d t h a t t h e m a t e r i a l w i l l h a v e a s t i f f n e s s a n d d e n s i t y s o m e w h a t a b o v e t h e m i n i m u m s h o w n i n T a b l e 6.9. L i k e w i s e , i f o n e c o n s i d e r s t h e r e l a t i v e l y l o w s t r a i n s to b e i n d u c e d i n t h e f i l l a n d t h e s i l o e f f e c t o f t h e s t o p e s , i t i s u n l i k e l y t h a t t h e u n c e m e n t e d f i l l w i l l e v e r c o m p a c t to i t s 161 o p t i m u m d e n s i t y a n d n e v e r a t t a i n t h e " m a x i m u m " s t i f f n e s s , t h e s t i f f n e s s of t h e i n d i v i d u a l g r a i n s . T A B L E 6 . 9 S u m m a r y of H i s t o r i c a l R a n g e o f M a t e r i a l P r o p e r t i e s S o u r c e T y p e E ( M P a ) kg/7r)3 F r o m T o F r o m T o F r o m T o 139 1 1 2 3 0 3 4 8 454 5 1 5 6 * 5 7 8 4 7 923 1 0 4 6 1117 11 12 132 1437 1551 1611 1710 U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d C e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d S a n d T a i l i n g s C e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d U n c e m e n t e d 6 . 9 1 1 . 0 8 2 . 7 1 1 . 0 4 . 1 1 2 . 6 5 . 6 3 2 . 0 6 . 9 2 0 , 0 0 0 6 9 . 0 6 . 9 3 4 . 5 1 3 5 . 0 2 7 5 . 8 9 6 . 5 1 2 . 4 5 4 . 4 2 8 . 7 7 8 . 0 690 4 1 3 . 7 6 8 9 . 5 0 . 2 0 0 . 7 0 0 . 2 5 0 . 2 5 0 . 2 5 6 0 . 0 5 0 . 0 2 8 5 . 0 0 . 4 5 1.6 M P a / % d i s p . -5 . 0 5 0 . 0 1 3 . 8 6 . 9 3 2 . 0 0 . 2 5 0 . 4 5 0 . 1 5 0 . 3 2 M i n i m u m M e d i u m M a x i m u m 1470 1910 1590 1870 L o w M e d i u m 1600 2000 2500 1620 2120 1600 2000 1600 2000 1970 1875 2160 2390 2100 162 6 .5 C O N C L U S I O N S It i s t h e r e f o r e a n t i c i p a t e d t h a t t h e b a c k f i l l m a t e r i a l w i l l b e s u i t a b l e to p r o v i d e a s u b - a n g u l a r to s u b - r o u n d e d s i l t y s a n d f i l l w i t h : c o e f f i c i e n t o f u n i f o r m i t y C u = 4 to 6 g r a i n s i z e d i s t r i b u t i o n , DJ^Q = .015 mm to . 05 mm v o i d r a t i o , e = 0 . 3 5 to 0 .75 a n d p o r o s i t y n = 0 . 2 6 to 0 .43 B e c a u s e t h e g r a i n s a r e l i k e l y s u b - a n g u l a r to s u b - r o u n d e d r a t h e r t h a n p l a t y , t h e s p e c i f i c s u r f a c e s h o u l d b e l o w r e s u l t i n g i n a r e l a t i v e l y h i g h p e r c o l a t i o n r a t e . It i s t h e r e f o r e a n t i c i p a t e d t h a t a n i n - p l a c e p e r c o l a t i o n r a t e i n t h e r a n g e of 5 c m / h r to 10 c m / h r s h o u l d b e e a s i l y a t t a i n a b l e . It i s a l s o e s t i m a t e d t h a t w i t h a v o i d r a t i o i n t h e r a n g e of 0 . 3 5 to 0 . 7 5 , t h e b a c k f i l l w i l l h a v e a n i n - p l a c e d e n s i t y i n t h e r a n g e of 1600 kg/ r rv* to 2200 kg/m -5 a n d a n a n g l e of i n t e r n a l f r i c t i o n i n t h e r a n g e of 3 5 ° t o 4 5 ° . In a d d i t i o n , w i t h a D ^ g s i z e o f 0 .015 mm to 0 . 0 5 m m , t h e m a x i m u m c a p i l l a r y t e n s i o n i s e s t i m a t e d to r a n g e f r o m 29 k P a to 96 k P a . A s s u m i n g a p e r c o l a t i o n r a t e of 5 c m / h r , t h i s 163 p h e n o m e n o n w o u l d p r o v i d e a s u b s t a n t i a l p o r t i o n of t h e c a p a c i t y o f t h e b a c k f i l l to s u p p o r t m i n e e q u i p m e n t . W h e n t h i s e f f e c t i s c o m b i n e d w i t h t h e i n f l u e n c e of t h e s o i l w e i g h t a n d t h e d i a m e t e r of t h e c o n t a c t a r e a b e t w e e n t h e t i r e a n d t h e b a c k f i l l , t h e b e a r i n g c a p a c i t y a p p e a r s to b e s u f f i c i e n t f o r a l l c r i t i c a l e v e n t s i n t h e m i n i n g c y c l e e x c e p t t h e c l e a n - u p of t h e f l o o r of t h e c u t . T o c o m p l e t e t h i s w o r k i t w i l l l i k e l y b e n e c e s s a r y to u s e t i r e p r e s s u r e s of 345 k P a o r l o w e r i n t h e b a c k t i r e s . It i s e s t i m a t e d t h a t t h e i n p u t p a r a m e t e r s r e q u i r e d f o r f i n i t e e l e m e n t a n a l y s e s l i k e l y v a r y w i t h t ime a s t h e m i n i n g p r o c e e d s . H o w e v e r , t h e s t i f f n e s s a n d d e n s i t y of e m p l a c e d f i l l l i k e l y i n c r e a s e m a r k e d l y d u r i n g t h e e x c a v a t i o n of t h r e e s u b s e q u e n t l i f t s a n d t h e r e a f t e r i n c r e a s e at a d e c r e a s i n g r a t e w i t h a d d i t i o n a l m i n i n g a n d f i l l i n g . T h u s , i t i s l i k e l y t h a t f o r t h e p u r p o s e of i n i t i a l d e s i g n a n d s e n s i t i v i t y a n a l y s i s t h e r e q u i r e d p a r a m e t e r s s h o u l d b e w i t h i n t h e r a n g e s g i v e n i n T a b l e 5 . 1 0 . 164 T A B L E 6 . 1 0 R a n g e of D e s i g n P a r a m e t e r s P a r a m e t e r M i n i m u m V a l u e M a x i m u m V a l u e E . ( M P a ) 6 . 9 690 0 . 1 5 0 . 4 5 e 1600 2200 It i s a n t i c i p a t e d t h a t t h e a c t u a l i n - p l a c e v a l u e s w i l l p r o b a b l y b e i n t h e o r d e r of 50 M p a f o r Y o u n g ' s M o d u l u s , 0 . 2 0 to 0 . 3 0 f o r P o i s s o n ' s R a t i o a n d 1800 k g / m 3 to 2000 k g / m 5 f o r t h e d e n s i t y . C H A P T E R 7 N U M E R I C A L M O D E L L I N G 166 7 .1 I N T R O D U C T I O N T h e s t u d i e s p r e s e n t e d i n t h e p r e c e d i n g c h a p t e r s h a v e p r o v i d e d b a s i c d a t a f o r n u m e r i c a l a n a l y s i s a n d e s t i m a t e s of o r e d i l u t i o n f r o m t h e s t o p e w a l l s . T h i s c h a p t e r a d d r e s s e s t h e q u e s t i o n of t h e s t r e s s d i s t r i b u t i o n s i n t h e s i l l p i l l a r , a n d i n a n d a r o u n d t h e b a c k f i l l e d s t o p e s u s i n g t h e d a t a g i v e n i n t h e e a r l i e r c h a p t e r s . T h e c h o i c e of n u m e r i c a l m o d e l l i n g to b e u s e d a n d t h e d e s i g n o f t h e m o d e l a r e f i r s t p r e s e n t e d a n d t h e i n p u t p a r a m e t e r s a r e r e v i e w e d . T h e f i n a l s e c t i o n s i n t h i s c h a p t e r t h e n p r e s e n t g e n e r a l r e s u l t s f r o m t h e m o d e l l i n g a n d d i s c u s s t h e i m p o r t a n c e of t h e f i n d i n g s . 167 7 . 2 N U M E R I C A L M O D E L L I N G 7 . 2 . 1 S e l e c t i n g a n u m e r i c a l m o d e l In s e l e c t i n g a n u m e r i c a l m o d e l w i t h w h i c h to a n a l y z e a n y g i v e n u n d e r g r o u n d o p e n i n g s t h e l i m i t a t i o n s a n d a v a i l a b i l i t y o f t h e m o d e l s a n d t h e m i n i n g m e t h o d m u s t b e c o n s i d e r e d . Wi th t h e s e a s p e c t s i n m i n d t h r e e d i s t i n c t l y d i f f e r e n t c o m p u t e r m o d e l s w e r e c o n s i d e r e d f o r u s e i n t h e a n a l y s i s of t h e M c L e l l a n M i n e . " B i t e m " , a t w o - d i m e n s i o n a l b o u n d a r y i n t e g r a l c o m p u t e r m o d e l d e v e l o p e d b y P . C . R i c c a r d e l l a ^ 5 a n d m o d i f i e d b y R . P a k a l n i s ^ 3 f o r u s e o n t h e c o m p u t e r 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 w a s c o n s i d e r e d f i r s t . T h i s p r o g r a m i s c a p a b l e of s o l v i n g t w o - d i m e n s i o n a l e l a s t i c i t y p r o b l e m s f o r a p i e c e w i s e h o m o g e n e o u s , i s o t r o p i c , l i n e a r l y e l a s t i c m a t e r i a l . H o w e v e r , i n o r d e r to s i m u l a t e t h e e f f e c t s of c u t - a n d - f i l l m i n i n g a n e w g e o m e t r i c m o d e l w i t h n e w b o u n d a r y c o n d i t i o n s m u s t b e m o d e l l e d f o r e a c h c u t - a n d - f i l l o p e r a t i o n . T h u s , i f t h e c u t - a n d - f i l l m i n i n g s e q u e n c e i s to b e m o d e l l e d i n 12 s t a g e s , 12 d i s t i n c t m o d e l s m u s t b e g e n e r a t e d . T h e s t r e s s c o n d i t i o n s f o r e a c h s u c c e s s i v e m o d e l m u s t b e o b t a i n e d f r o m t h e o u t p u t d a t a of t h e p r e c e d i n g s t a t e . T h e s e c o n d n u m e r i c a l m o d e l c o n s i d e r e d w a s M i n t a b , a 168 t w o - d i m e n s i o n a l p r o g r a m d e v e l o p e d at C o n s o l i d a t e d G o l d f i e l d s C o r p o r a t i o n i n S o u t h A f r i c a b y S . L . C r o u c h a n d m o d i f i e d b y Y u , T o e w s a n d W o n g ^ l . M i n t a b i s c a p a b l e of 1 ) S i m u l a t i n g c o m p l e x s t o p e - a n d - p i l l a r i n a t a b u l a r o r e b o d y . 2 ) M o d e l l i n g a n y n u m b e r of m i n i n g s e q u e n c e s . 3 ) S i m u l a t i n g l i n e a r c o m p r e s s i b i l i t y of p i l l a r s , r e m n a n t s o r a b u t m e n t s . 4 ) M o d e l l i n g d i f f e r e n t m a t e r i a l p r o p e r t i e s f o r t h e o r e ' z o n e a n d t h e s u r r o u n d i n g r o c k m a s s . 5) M o d e l l i n g l i n e a r e l a s t i c b a c k f i l l . 6 ) M o d e l l i n g a r b i t r a r y i n i t i a l s t r e s s f i e l d s . H o w e v e r , t h i s p r o g r a m i s l i m i t e d to a h o m o g e n e o u s r o c k m a s s s u r r o u n d i n g t h e o r e z o n e . In a d d i t i o n , t h e m o d e l i s l i m i t e d to t h e s i m u l a t i o n of a p l a n a r d e p o s i t w i t h a t h i c k n e s s t h a t i s s m a l l c o m p a r e d to i t s l a t e r a l e x t e n t a n d t h e d e p t h b e l o w t h e s u r f a c e . In e f f e c t , t h i s m o d e l o n l y s i m u l a t e s a l o n g i t u d i n a l s e c t i o n of t h e o r e b o d y a n d d o e s no t a c c o u n t for v a r i a t i o n i n t h e t h i c k n e s s of t h e o r e z o n e . T h e m o d e l c h o s e n for s i m u l a t i n g t h e m i n i n g of t h e c u t - a n d - f i l l s t o p e s a t t h e M c L e l l a n M i n e c o m b i n e s t h e c a p a b i l i t i e s o f b o t h t h e B i t e m a n d M i n t a b m o d e l s i n a t w o - d i m e n s i o n a l f i n i t e e l e m e n t m o d e l . T h i s m o d e l , I M S - F E A P , w a s d e v e l o p e d b y 169 Z i e n k o w i c z ' ^ a n d m o d i f i e d b y M . A . S t o a k e s f o r u s e o n an H . P . 9836 m i c r o c o m p u t e r . T h e m o d e l h a s t h e c a p a b i l i t y o f 1) M o d e l l i n g a n y n u m b e r of h o m o g e n e o u s , i s o t r o p i c , l i n e a r - e l a s t i c z o n e s . 2) S i m u l a t i n g a n y n u m b e r of e x c a v a t i o n a n d / o r b a c k f i l l i n g s e q u e n c e s . 3) M o d e l l i n g l i n e a r e l a s t i c b a c k f i l l . 4 ) M o d e l l i n g a r b i t r a r y i n i t i a l s t r e s s f i e l d s u s i n g e i t h e r f o r c e v e c t o r s o r d i s p l a c e m e n t s o n t h e b o u n d a r y of t h e m o d e l . 5) M o d e l l i n g t h e s e l f - w e i g h t of t h e m a t e r i a l s . 6) M o d e l l i n g v a r i a t i o n i n t h e t h i c k n e s s of t h e o r e b o d y T h u s , t h e I M S - F E A P m o d e l i s m u c h m o r e a d a p t a b l e f o r m o d e l l i n g t h e c u t - a n d - f i l l m i n i n g of a n i r r e g u l a r g o l d d e p o s i t . T h e o n l y m a j o r l i m i t a t i o n o f t h i s m o d e l i s t h e c o m p l e x i t y of t h e g e o m e t r y a n d t h e " f i n e n e s s " of t h e m e s h t h a t c a n b e u s e d . 170 7 .2 .2 Des ign of the geometr ica l model 7 . 2 . 2 . 1 Cho ice of Geo log ica l Sect ions Upon c o n s i d e r i n g the mechanics of the t r a n s f e r of s t r ess f rom the s u r r o u n d i n g rock to the b a c k f i l l in the s t o p e s , it is rea l i zed that the s t r e s s b u i l d - u p in the b a c k f i l l must be re la ted to the amount of s t r a i n e x i s t i n g in the f i l l , the e las t ic modulus of the f i l l and the c o n f i n i n g s t r e s s in the f i l l . A s the s t ra in and con f i n i ng s t r e s s in the b a c k f i l l i n c r e a s e , the d e n s i t y , and t h e r e f o r e , e las t ic modulus of the f i l l i n c r e a s e . T h e r e f o r e fo r g i ven v i r g i n s t r e s s c o n d i t i o n s , the f i l l wi l l be sub jec ted to g rea te r c o n f i n i n g s t r ess and l a r g e r s t r a i ns in na r row s topes compared to w ider s topes and the suppo r t o f fe red b y the f i l l wi l l be g rea te r f o r a na r row s t o p e . La te ra l " a r c h i n g " of the b a c k f i l l d u r i n g subsequen t l i f ts would be minimized in a l l s topes by the s u b s e q u e n t " f l o o d i n g " of the b a c k f i l l d u r i n g and a f te r the emplacement of la ter l i f ts of b a c k f i l l . On th is bas is the c r o s s - s e c t i o n with the t h i c kes t ore z o n e , Sec t ion 0+00 ( F i g u r e 2.3) was chosen for deta i led numer ica l mode l l i ng . 171 The results obtained from this geometrical model will be conservative in that the support offered by the backfill will be lower than for other sections. As the effects of backfilling could not be accurately modelled in plan, no horizontal sections were modelled. Because of the geometry of the stopes (Length = 2.5 X height = 10 to 20 x width) it was also felt that the longitudinal section could not be accurately modelled with a two-dimensional model. The numerical modelling presented in this chapter therefore consists of a detailed analysis of Section 0+00. 7.2.2.2 Detailed Geometry of Section 0+00 As can be seen in Figure 2.2 and 2.3 the stopes at the McLellan Mine dip towards the north at approximately 84° to horizontal and the land surface slopes off to the south at approximately 6 ° , nearly parallel to the plunge of the major principal stress. Therefore the geological section was rotated 6° counterclockwise for ease of numerical modelling. On this rotated section a geometrical model consisting of constant strain triangular and quadrilateral elements was designed with 514 elements and 419 nodes (Figure 7.1) extending from surface to a depth of 468 m and approximately 240 metres to either side of the stope. The elements range in MESH PLOT - NUMBERING: NONE PLOT RANGE - 0, 41G, -500, 0 IMS - * * H MCLELLRN MINE: TEST MESH HORIZONTRL DISPS. F i g u r e 7 . 1 D e s i g n of G e o m e t r i c a l M o d e l f o r A n a l y s i s b y F i n i t e E l e m e n t M e t h o d 173 s i z e f r o m a t r i a n g u l a r e l e m e n t 2 . 5 4 m e t r e s w i d e a n d 4 m e t r e s h i g h i n t h e a r e a o f t h e s i l l p i l l a r to a q u a d r i l a t e r a l o f 48 m e t r e s b y 96 m e t r e s i n t h e b o t t o m c o r n e r s of t h e m o d e l . A s s h o w n i n F i g u r e 7 . 2 t h e m o d e l i n c o r p o r a t e s t w o s t o p e s , s e p a r a t e d b y a s i l l p i l l a r i n w h i c h a d r a i n a g e t u n n e l i s e x c a v a t e d . A s t h e e x c a v a t i o n p r o c e e d s t h e h e i g h t of t h e s i l l p i l l a r d e c r e a s e s to a m i n i m u m . I n i t i a l r u n s of t h e m o d e l s h o w e d t h a t t h e e n d e f f e c t s o f t h e b o u n d a r y c o n d i t i o n s a r e m i n i m a l w i t h i n t h e m o d e l a n d a r e n e g l i g i b l e i n t h e a r e a o f c o n c e r n . 7 . 2 . 3 S i m u l a t i o n of E x c a v a t i o n S e q u e n c e In o r d e r to a c c u r a t e l y m o d e l t h e s t r e s s e s i m p o s e d u p o n t h e b a c k f i l l a n d t h e s i l l p i l l a r t h e m i n i n g s e q u e n c e m u s t a l s o b e c o n s i d e r e d . A t M c L e l l a n M i n e t h e c u t - a n d - f i l l m i n i n g m e t h o d i s t o b e e m p l o y e d as f o l l o w s : 1) E x c a v a t e a c e n t r e h e a d i n g t o t h e f u l l h e i g h t ( 4 . 5 m) o f t h e c u t . 2) S l a s h t h e s i d e s o f t h e c u t to t h e f u l l s t o p e w i d t h ( 3 . 0 to 2 8 . 0 m ) . 3) B a c k f i l l t o w i t h i n 0 . 6 m o f t h e t o p of t h e c u t . 4 ) E x c a v a t e t h e c e n t r e h e a d i n g i n t h e n e x t c u t , l e a v i n g 0 .6 m of b r o k e n o r e o n top of t h e b a c k f i l l . 174 5) R e p e a t s t e p 2 ) . 6 ) C l e a n u p t h e 0 . 6 m of b r o k e n o r e o n t h e f l o o r of t h e c u t . 7 ) R e p e a t s t e p s 3 ) , 4 ) , 5) a n d 6) to t h e top of t h e s t o p e . V e r y l i t t l e c l o s u r e of t h e s t o p e w a l l s o c c u r s w i t h t h e e x c a v a t i o n of t h e b o t t o m h a l f of t h e s t o p e s . H e n c e , a c u t - a n d - f i l l c y c l e m o d e l l i n g 24 m e t r e s of e x c a v a t i o n o r a p p r o x i m a t e l y 5 m i n i n g c y c l e s w a s c h o s e n f o r t h e u p p e r s t o p e a n d f o r t h e l o w e r t h r e e q u a r t e r s o f t h e l o w e r s t o p e ( F i g u r e 7 . 1 ) . A s t h e m o d e l l e d e x c a v a t i o n o f t h e l o w e r s t o p e a p p r o a c h e d t h e b o t t o m o f t h e u p p e r s t o p e t h e m o d e l l e d c y c l e w a s r e d u c e d t o a h e i g h t of 4 m e t r e s to p r o v i d e m o r e d e t a i l i n t h e a r e a of t h e s i l l p i l l a r . T h e c y c l e s of c u t - a n d - f i l l w e r e m o d e l l e d i n s t a g e s as f o l l o w s : 1 ) S i m u l a t e t h e e x c a v a t i o n o f t h e f i r s t c u t b y r e d u c i n g t h e e l a s t i c m o d u l u s a n d d e n s i t y o f t h o s e e l e m e n t s to n e a r z e r o . 2 ) P e r f o r m a n e l a s t i c a n a l y s i s . 3 ) S i m u l a t e t h e b a c k f i l l i n g o f t h a t c u t b y i n c r e a s i n g t h e e l a s t i c m o d u l u s a n d d e n s i t y to t h a t of t h e b a c k f i l l . 4 ) S i m u l a t e t h e e x c a v a t i o n of t h e n e x t c u t b y r e d u c i n g t h e e l a s t i c m o d u l u s a n d d e n s i t y of t h o s e e l e m e n t s to n e a r z e r o . 5) R e p e a t s t e p s 2 , 3 a n d 4 u n t i l t h e " e x c a v a t i o n " of t h e s t o p e i s c o m p l e t e d . 175 F I L E NO. I ELEVATION 1400m 12 -1280m M60n 1 4 0 0 m 1280m 1 1 6 0 m F i g u r e 7 . 2 S e q u e n c e of S i m u l a t i o n of M i n i n g . R o c k i s h a t c h e d , M i n e d A r e a s b l a n k a n d B a c k f i l l s h a d e d . T h e f i l e n u m b e r r e f e r s to t h e o u t p u t d a t a f i l e f o r t h a t s t a g e of t h e E x c a v a t i o n . 7 . 2 . 4 M o d e l l i n g R e m e d i a l M e a s u r e s 176 In o r d e r to m i n i m i z e t h e s a f e d i m e n s i o n s o f t h e s i l l p i l l a r v a r i o u s r e m e d i a l m e a s u r e s w e r e c o n s i d e r e d a n d a n a l y z e d w i t h t h e n u m e r i c a l m o d e l . T h e s e m e a s u r e s c o n s i s t e d o f : 1) s i m u l a t i n g a c o n c r e t e l i n i n g i n t h e d r a i n a g e t u n n e l b y i n c r e a s i n g t h e b u l k m o d u l u s o f t h a t e l e m e n t . 2 ) S i m u l a t i n g g r o u t i n g o f t h e b a c k f i l l i n t h e l o w e r e l e m e n t s o f t h e u p p e r s t o p e b y i n c r e a s i n g t h e b u l k m o d u l u s a n d d e c r e a s i n g t h e P o i s s o n ' s R a t i o f o r t h o s e e l e m e n t s . 3 ) S i m u l a t i n g t h e u s e o f c e m e n t e d f i l l i n t h e u p p e r p o r t i o n of t h e l o w e r s t o p e b y m e t h o d s s i m i l a r to i t em 2 . 7 . 3 D E S I G N P A R A M E T E R S T h e n u m e r i c a l m o d e l l i n g a n d t h e s u b s e q u e n t a n a l y s i s r e q u i r e s t h e u s e of i n p u t d a t a d e r i v e d i n p r e v i o u s c h a p t e r s . T h e s e i n p u t p a r a m e t e r s c o n s i s t o f t h e d e n s i t y , b u l k m o d u l u s a n d P o i s s o n ' s r a t i o o f t h e r o c k m a s s a n d t h e b a c k f i l l f o r a n y g i v e n e l e m e n t , a n d t h e v i r g i n s t r e s s c o n d i t i o n s a t t h e s i t e . A s t h e a c c u r a c y o f t h e n u m e r i c a l m o d e l i s d e p e n d e n t u p o n t h e a c c u r a c y of t h e i n p u t p a r a m e t e r s , t h e d e s i g n v a l u e s w i l l b e r e v i e w e d a n d d i s c u s s e d w i t h r e s p e c t to t h e m o d e l a n d t h e a c t u a l s i t e c o n d i t i o n s . T h e v a l u e s u s e d i n t h e m o d e l l i n g a r e s u m m a r i z e d i n T a b l e 7 . 1 . 177 T A B L E 7 . 1  S u m m a r y of D e s i g n P a r a m e t e r s M a t e r i a l P r o p e r t i e s I n - S i t u S t r e s s e s M a t e r i a l T y p e E l a s t i c M o d u l u s ( G P a ) P o i s s o n ' s R a t i o D e n s i t y ( k g / m 3 ) S i (TV M P a crv M P a crv M P a F r e s h R o c k W e a t h e r e d R o c k C o n s o l . F i l l H y d r a u l i c F i l l 50 10 10 6 X IO" 4 to 0 . 6 0 . 2 5 0 . 2 5 0 . 2 5 0 . 2 5 to 0 . 4 5 2960 2960 2000 1600 to 2200 2 . 8 2 1.1 1.0 crv = 2 . 9 6 g * 178 7 . 3 . 1 R o c k M a s s P a r a m e t e r s 7 . 3 . 1 . 1 Y o u n g ' s M o d u l u s A s d i s c u s s e d i n C h a p t e r F o u r , t h e g r e a t e s t b u l k of t h e r o c k m a s s i s e s t i m a t e d to h a v e a Y o u n g ' s M o d u l u s of 50 G P a . A b o v e e l e v a t i o n 1400 m a n d i n t h e N o r t h S h e a r t h e r o c k m a s s i s e s t i m a t e d to h a v e a n e l a s t i c m o d u l u s of l O G P a . D u e to t h e l i m i t e d w i d t h of t h e N o r t h S h e a r w h e r e i t w i l l no t b e e x c a v a t e d i n t h e s t o p e s , a n d i t s d i s t a n c e f r o m s t o p e s at t h e e l e v a t i o n of t h e s i l l p i l l a r ( f r o m 3 . 0 m to 6 . 0 m) t h e i n f l u e n c e o f t h e N o r t h S h e a r o n t h e s t i f f n e s s a n d s t r e n g t h of t h e s i l l p i l l a r w i l l b e m i n i m a l . T h u s , t h e N o r t h S h e a r w a s no t c o n s i d e r e d as a s e p a r a t e u n i t w i t h i n t h e n u m e r i c a l m o d e l . T h e e f f e c t o f t h e N o r t h S h e a r o n t h e s t a b i l i t y o f t h e h a n g i n g w a l l w i l l b e d i s c u s s e d i n C h a p t e r 8 . 7 . 3 . 1 . 2 P o i s s o n ' s R a t i o T h e l a b o r a t o r y t e s t i n g c o m p l e t e d o n d i a m o n d d r i l l c o r e i n d i c a t e s t h a t t h e P o i s s o n ' s R a t i o f o r i n t a c t r o c k s a m p l e s f r o m t h e M c L e l l a n M i n e r a n g e s f r o m 0 . 1 7 to 0 . 2 9 . A s t h e s t i f f n e s s of t h e r o c k m a s s i s r e l a t i v e l y i n s e n s i t i v e to s m a l l c h a n g e s i n P o i s s o n ' s R a t i o a n a v e r a g e v a l u e of 0 . 2 5 w a s u s e d i n t h e n u m e r i c a l m o d e l l i n g . T h i s v a l u e i s l i k e l y c o n s e r v a t i v e 179 c o n s i d e r i n g t h a t t h e c h l o r i t i z e d a n d e s i t e , w i t h a P o i s s o n ' s R a t i o o f 0 . 2 0 , c o m p r i s e s a p p r o x i m a t e l y 50% of t h e r o c k m a s s . 7 . 3 . 1 . 3 D e n s i t y T h e a v e r a g e d e n s i t y of t h e s a m p l e s s u b j e c t e d to s p e c i f i c g r a v i t y t e s t s i s 2960 k g / m 3 . A s t h i s v a l u e c o r r e s p o n d s w e l l w i t h t h e v a r i a t i o n i n e s t i m a t e d v e r t i c a l s t r e s s w i t h d e p t h , i t i s a c c e p t e d f o r n u m e r i c a l m o d e l l i n g p u r p o s e s . 7 . 3 . 2 H y d r a u l i c B a c k f i l l P a r a m e t e r s In t h e l i t e r a t u r e r e v i e w d i s c u s s e d i n C h a p t e r S i x , a r a n g e of i n p u t p a r a m e t e r s f o r t h e h y d r a u l i c b a c k f i l l w a s r e c o m m e n d e d f o r u s e i n t h e n u m e r i c a l m o d e l . T h e s e r e c o m m e n d e d r a n g e s a r e : E = 0 .69 M P a to 690 M P a = 0 . 2 5 to 0 . 4 5 = 1600 k g / m 3 t o 2200 k g / m 3 7 . 3 . 3 S t i f f B a c k f i l l P a r a m e t e r s In o r d e r to m o d e l " s t i f f e r " b a c k f i l l to s i m u l a t e t h e e f f e c t s of g r o u t i n g a n d / o r c e m e n t e d b a c k f i l l r e a l i s t i c v a l u e s f o r t h e i n p u t p a r a m e t e r s w e r e c o n s i d e r e d . O n l y t w o s o u r c e s q u o t e d i n 180 C h a p t e r 6 d e f i n e d v a l u e s f o r c e m e n t e d f i l l . T h e s e v a l u e s r a n g e d f r o m 60 M P a to 2 0 , 0 0 0 M P a f o r Y o u n g ' s M o d u l u s a n d 2000 k g / m 3 to 2500 k g / m 3 f o r t h e d e n s i t y . No v a l u e s w e r e q u o t e d f o r P o i s s o n ' s R a t i o . H o w e v e r , i t i s a n t i c i p a t e d t h a t t h e P o i s s o n ' s R a t i o o f c e m e n t e d s a n d w o u l d b e n e a r t h a t of a weak r o c k s u c h as s a n d s t o n e . T h e v a l u e s c h o s e n f o r c e m e n t e d / g r o u t e d f i l l a r e t h e r e f o r e : E = 10 G P a •N = 0 . 2 5 Q_ = 2000 k g / m 3 7 . 3 . 4 I n - s i t u S t r e s s T h e r e s u l t s o f t h e i n - s i t u s t r e s s m e a s u r e m e n t s i n d i c a t e t h a t : 1 ) T h e m a j o r 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 n e a r p e r p e n d i c u l a r t o t h e o r e b o d y at a n a z i m u t h o f 3 3 6 ° r e l a t i v e to m i n e n o r t h a n d a p l u n g e of +6° to t h e n o r t h w e s t . 2 ) T h e 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 i s n e a r l y p a r a l l e l to t h e s t r i k e o f t h e o r e b o d y . 3 ) T h e m i n o r 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 d o w n t h e d i p of t h e o r e b o d y a t an a z i m u t h of 2 1 ° r e l a t i v e to m i n e n o r t h a n d a d i p o f - 8 4 ° to t h e n o r t h w e s t . T h e m a g n i t u d e of t h e p r i n c i p a l s t r e s s e s , b e t w e e n t h e 240 m l e v e l a n d t h e 370 m l e v e l w e r e e s t i m a t e d to b e : 181 O J = 2 0 . 4 9 M p a 0"2 = 1 .13 o v 03 = 0 . 9 6 crv w h e r e o v = 2 . 9 6 g z g = a c c e l e r a t i o n d u e to g r a v i t y z = d e p t h i n m e t r e s F o r m o d e l l i n g p u r p o s e s t h e p r i n c i p a l s t r e s s e s a r e a s s u m e d to b e o r t h o g o n a l to t h e p r o p o s e d s t o p e s . In a d d i t i o n a n a v e r a g e s t r e s s r a t i o of 0 1 = 2 . 3 2 o v w a s a s s u m e d . O n t h i s b a s i s h o r i z o n t a l d i s p l a c e m e n t s w e r e c a l c u l a t e d a n d a p p l i e d to e a c h n o d e o n t h e v e r t i c a l b o u n d a r i e s of t h e g e o m e t r i c a l m o d e l . 7 . 4 N U M E R I C A L M O D E L L I N G I N V E S T I G A T I O N S A s d i s c u s s e d i n S e c t i o n 7 . 3 i n t h e i n i t i a l e i g h t r u n s of t h e f i n i t e e l e m e n t m o d e l , t h e s e n s i t i v i t y of t h e m o d e l to a r a n g e of v a l u e s of t h e e l a s t i c m o d u l u s , P o i s s o n ' s R a t i o a n d d e n s i t y of t h e b a c k f i l l w a s i n v e s t i g a t e d . In a d d i t i o n , t h e n i n t h r u n w a s c o m p l e t e d w i t h o u t m o d e l l i n g t h e b a c k f i l l m a t e r i a l to s i m u l a t e a n o p e n s t o p e . T h e r a n g e of m a t e r i a l p r o p e r t i e s u s e d i n t h e s e r u n s i s d e t a i l e d i n T a b l e 7 . 2 . 182 T a b l e 7 . 2  R a n g e of M a t e r i a l P r o p e r t i e s  U s e d i n S e n s i t i v i t y A n a l y s e s R u n N o . E ( M P a ) £ > ( k q / W ) 1 6 9 . 0 0 . 3 0 1800 2 6 9 . 0 0 . 3 0 2000 3 6 9 . 0 0 . 3 0 2200 4 6 9 . 0 0 . 2 5 2000 5 6 9 . 0 0 . 3 5 2000 6 6 9 . 0 0 . 4 5 2000 7 6 . 9 0 0 . 3 0 2000 8 6 9 0 . 0 0 . 3 0 2000 9 .001 0 . 5 0 10 T h e s e r u n s w e r e c o m p l e t e d w i t h o u t m o d e l l i n g t h e e x c a v a t i o n o f t h e d r a i n a g e t u n n e l . In s u b s e q u e n t r u n s t h e e x c a v a t i o n of t h e d r a i n a g e t u n n e l w a s m o d e l l e d a s w e r e r e m e d i a l m e a s u r e s i n t h e t u n n e l a n d t h e e f f e c t s of g r o u t e d f i l l i n t h e u p p e r s t o p e a n d c e m e n t e d f i l l i n t h e l o w e r s t o p e s . 183 7 . 5 R E S U L T S T h e r e s u l t s of t h e s e n s i t i v i t y a n a l y s i s a r e s u m m a r i z e d i n T a b l e 7 . 3 w h i c h c o m p a r e s t h e c l o s u r e o f t h e l o w e r s t o p e a n d t h e a v e r a g e p r i n c i p a l s t r e s s i n t h e s i l l p i l l a r f o r v a r i o u s v a l u e s o f t h e b a c k f i l l p a r a m e t e r s a n d f o r t h e c a s e o f n o b a c k f i l l . M a j o r p r i n c i p a l s t r e s s c o n t o u r p l o t s a r e g i v e n f o r s u b s e q u e n t r u n s i n A p p e n d i x X V I I f o r t h e l a s t 6 s t a g e s o f e x c a v a t i o n o f r u n m o d e l l i n g t h e u n s u p p o r t e d d r a i n a g e t u n n e l . A p p e n d i x X V I I I c o n t a i n s s i m i l a r p l o t s f o r a r e i n f o r c e d d r a i n a g e t u n n e l , t h e g r o u t i n g of t h e b a c k f i l l i n t h e u p p e r s t o p e a n d t h e u s e of c e m e n t e d f i l l i n t h e u p p e r p o r t i o n of t h e l o w e r s t o p e f o r t h e f i n a l s t a g e s of e x c a v a t i o n . 7 . 6 D I S C U S S I O N F r o m t h e o u t p u t p r e s e n t e d i n T a b l e 7 . 3 i t i s a p p a r e n t t h a t t h e b a c k f i l l d o e s p r o v i d e s i g n i f i c a n t s u p p o r t to t h e s t o p e w a l l s . H o w e v e r , w i t h i n t h e r a n g e o f m a t e r i a l p r o p e r t i e s a n a l y z e d , t h e e f f e c t of v a r y i n g a n y o f t h e s e p a r a m e t e r s i s n e g l i g i b l e . 184A T A B L E 7 . 3 C o m p a r i s o n of C l o s u r e of L o w e r S t o p e  a n d A v e r a g e P r i n c i p a l S t r e s s e s i n S i l l P i l l a r W i th V a r i a b l e B a c k f i l l P r o p e r t i e s R u n E e C l o s u r e A v e . P i l l a r S t r e s s N o . V at m i d p o i n t M P a ( M P a ) ( k q / m 3 ) (mm) M a j o r M i n o r 1 6 9 . 0 0 . 2 5 2000 8 8 . 8 8 1 2 9 . 0 1 6 . 3 2 6 9 . 0 0 . 3 5 2000 8 8 . 7 6 1 2 8 . 8 1 6 . 3 3 6 9 . 0 0 . 4 5 2000 8 8 . 5 6 1 2 8 . 5 1 6 . 3 A 6 9 . 0 0 . 3 0 1800 8 8 . 8 3 1 2 8 . 9 1 6 . 3 5 6 9 . 0 0 . 3 0 2000 8 8 . 8 3 1 2 8 . 9 1 6 . 3 6 6 9 . 0 0 . 3 0 2200 8 8 . 8 3 1 2 8 . 9 1 6 . 3 7 6 . 9 0 . 3 0 2000 8 8 . 8 7 1 2 9 . 0 1 6 . 3 8 6 9 0 . 0 0 . 3 0 2000 8 8 . 7 8 1 2 8 . 6 1 6 . 3 9 0 . 0 1 0 . 5 0 1.0 9 7 . 8 0 1 3 1 . 8 1 6 . 5 In a d d i t i o n , t h e u s e of c o n s o l i d a t e d b a c k f i l l a b o v e a n d b e l o w t h e s i l l p i l l a r r e s u l t s i n l e s s s e v e r e s t r e s s c o n d i t i o n s w i t h i n t h e p i l l a r . T h e s e e f f e c t s a r e , h o w e v e r d i f f i c u l t to a s s e s s w i t h o u t f u r t h e r d e t a i l e d a n a l y s e s of t h e d a t a o b t a i n e d f r o m t h e n u m e r i c a l m o d e l d u e to t h e e f f e c t of d i f f e r e n t s t r e s s - s t r a i n a n d s t r e n g t h c h a r a c t e r i s t i c s of t h e c o n s o l i d a t e d b a c k f i l l a n d t h e r o c k p o r t i o n s of t h e " p i l l a r " . It s h o u l d a l s o b e n o t e d t h a t r e g a r d l e s s of a n y r e m e d i a l m e a s u r e s to b e t a k e n i n a n d a r o u n d t h e s i l l p i l l a r , t h e a d v a n c e o f t h e l o w e r s t o p e r o o f t o w a r d s t h e b o t t o m o f t h e u p p e r s t o p e r e s u l t s i n h i g h s t r e s s c o n c e n t r a t i o n s a t t h e e x t r e m i t i e s of b o t h s t o p e s . F u r t h e r d i s c u s s i o n of t h e r e s u l t s a r e p r e s e n t e d i n C h a p t e r E i g h t . 184 B T A B L E 7 . 4 S u m m a r y of S t r e s s e s i n B a c k f i l l  i n L o w e r S t o p e a l o n g t h e F o o t w a l l P i l l a r W i d t h = 1 2 . 5 m Efm=69 M P a » f n l = 0 . 3 0 O f m = 2 0 0 0 k g / m 3 E l e m e n t N o . H e i g h t a b o v e I n v e r t (m) P r i n c i p a l S t r e s s e s i n F i l l 91 ( M P a ) M P a ) 61 2 . 4 0 . 3 0 0 . 1 8 74 1 1 . 5 0 . 3 1 0 . 0 6 82 1 9 . 7 0 . 3 3 - 0 . 0 5 102 2 7 . 7 0 . 3 6 - 0 . 0 9 110 3 5 . 5 0 . 3 9 - 0 . 0 9 119 4 3 . 7 0 . 4 2 - 0 . 0 8 128 5 1 . 8 0 .47 - 0 . 0 2 146 5 9 . 8 0 . 5 7 0 . 0 3 153 6 7 . 6 0 . 6 5 0 . 1 2 162 7 5 . 5 0 . 6 3 0 . 1 3 171 8 3 . 5 0 . 6 1 0 . 1 3 190 9 1 . 6 0 . 5 8 0 . 1 3 185 7 . 7 C O N C L U S I O N S A s a r e s u l t o f d e t a i l e d n u m e r i c a l a n a l y s e s o f t h e c o n d i t i o n s a t t h e M c L e l l a n M i n e i t c a n b e c o n c l u d e d t h a t : 1) T h e b a c k f i l l i n a c u t - a n d - f i l l m i n e p r o v i d e s s i g n i f i c a n t s u p p o r t to t h e s t o p e w a l l s b y i n c r e a s i n g t h e c o n f i n i n g s t r e s s a c t i n g o n t h e w a l l s . 2) T h e s u p p o r t p r o v i d e d b y t h e b a c k f i l l o n l y s l i g h t l y i m p r o v e s t h e s t r e s s c o n d i t i o n s i n t h e s i l l p i l l a r . 3 ) W i t h i n t h e a c c e p t e d r a n g e of m a t e r i a l p r o p e r t i e s of t h e b a c k f i l l , t h e e f f e c t o f v a r y i n g t h e s e p r o p e r t i e s i s no t s i g n i f i c a n t . T h e r e f o r e , 4 ) T h e u s e of a l i n e a r e l a s t i c b a c k f i l l m a t e r i a l w i t h c o n s t a n t s t i f f n e s s c h a r a c t e r i s t i c s i s a d e q u a t e f o r t h e f i n i t e e l e m e n t m o d e l l i n g of t h e M c L e l l a n M i n e . 5) T h e r e m e d i a l m e a s u r e s m o d e l l e d w i t h t h e f i n i t e e l e m e n t m o d e l a p p e a r to s i g n i f i c a n t l y i m p r o v e t h e s t r e s s c o n d i t i o n s w i t h t h e s i l l p i l l a r . 6) T h e d e s i g n o f a m i n i m u m w i d t h s i l l p i l l a r b e t w e e n t h e t w o s t o p e s may s t e r i l i z e s i g n i f i c a n t o r e r e s e r v e s b o t h a b o v e a n d b e l o w t h e s e s t o p e s . A n a l y s i s o f t h e o u t p u t d a t a f r o m t h e n u m e r i c a l m o d e l l i n g i s r e q u i r e d to d e t e r m i n e t h e m i n i m u m s a f e p i l l a r w i d t h a n d t h e e f f e c t s o f r e m e d i a l m e a s u r e s . W o r k s h o u l d a l s o b e c o m p l e t e d to d e t e r m i n e t h e r e q u i r e m e n t s f o r t e m p o r a r y s u p p o r t w i t h i n t h e s t o p e s d u r i n g m i n i n g a n d f o r l o n g t e r m s u p p o r t o f t h e s i l l p i l l a r . C H A P T E R 8 D E S I G N A N A L Y S E S 187 8 .1 I N T R O D U C T I O N T h e d a t a p r o v i d e d b y t h e f i n i t e e l e m e n t m o d e l l i n g , t h e r o c k m a s s c l a s s i f i c a t i o n a n d t h e l a b o r a t o r y t e s t i n g c a n now b e s t u d i e d s y s t e m a t i c a l l y to p r o v i d e a g e o m e c h a n i c a l d e s i g n of t h e v a r i o u s m i n e c o m p o n e n t s . T h i s p h a s e of t h e r e s e a r c h i n v o l v e s t h e d e s i g n of two d i s t i n c t c o m p o n e n t s of t h e m i n e , t h e s t o p e s a n d t h e s i l l p i l l a r . B o t h of t h e s e c o m p o n e n t s m u s t b e a n a l y z e d w i t h r e s p e c t to s t r u c t u r a l a n d / o r s t r e s s - c o n t r o l l e d f a i l u r e s . In t h e s t o p e s , t h e s t a b i l i t y o f t h e w a l l s m u s t b e c o n s i d e r e d o n b o t h a l o n g t e r m a n d s h o r t t e r m b a s i s . T h e s t a b i l i t y o f t h e r o o f o f e a c h c u t n e e d o n l y b e c o n s i d e r e d o n a s h o r t t e r m b a s i s . T h e s t u d y of t h e f i n a l s i l l p i l l a r a l s o a d d r e s s e s t h e l o n g t e r m s t a b i l i t y o f t h e f i n a l r o o f o f t h e l o w e r s t o p e . T h e g e o m e c h a n i c a l d e s i g n of t h e m i n e c o m p o n e n t s i s t h e r e f o r e p r e s e n t e d i n t w o s e c t i o n s d e a l i n g w i t h t h e s t o p e d e s i g n a n d t h e s i l l p i l l a r d e s i g n . T h e s e c t i o n o n t h e s t o p e d e s i g n i s p r e s e n t e d i n t w o s u b s e c t i o n s d e a l i n g w i t h t h e w a l l s a n d r o o f . 188 In e a c h of t h e s e s e c t i o n s t h e s t a b i l i t y o f t h e c o m p o n e n t i s c o n s i d e r e d f i r s t w i t h r e s p e c t to s t r u c t u r a l f a i l u r e a n d t h e n s t r e s s - c o n t r o l l e d f a i l u r e . T h e r e s u l t s of t h e s e a n a l y s e s a r e t h e n d i s c u s s e d i n d e t a i l p r i o r to t h e p r e s e n t a t i o n of c o n c l u s i o n s . 189 8 . 2 S T O P E D E S I G N F o r e a s e of p r e s e n t a t i o n , t h e d e s i g n a n a l y s e s of t h e s t o p e s i s s p l i t i n t o two d i s t i n c t s e c t i o n s d e a l i n g f i r s t w i t h t h e s t o p e w a l l s a n d t h e n w i t h t h e a d v a n c i n g s t o p e r o o f . A s m i n i n g p r o c e e d s , t h e w a l l o f e a c h c u t i s b u r i e d w i t h t h e p l a c e m e n t o f t h e n e x t l a y e r o f f i l l . In a d d i t i o n , e a c h c u t e x p o s e s a n e w r o o f . T h u s , t h e d e s i g n of t h e s t o p e w a l l s a n d r o o f c o n s i s t s of p r o v i d i n g s a f e w o r k i n g c o n d i t i o n s f o r t h e d u r a t i o n o f e a c h c u t - a n d - f i l l c y c l e . A s d i s c u s s e d i n C h a p t e r F o u r , e a c h c y c l e i s a n t i c i p a t e d to t a k e 2-1/2 t o 3 w e e k s to c o m p l e t e . T h u s , t h e i n t e g r i t y o f e a c h s e c t i o n o f t h e s t o p e w a l l s a n d r o o f m u s t b e m a i n t a i n e d f o r a m i n i m u m of t h r e e w e e k s . In a d d i t i o n , t h e d e s i g n w i l l a n a l y z e t h e s u p p o r t p r o v i d e d b y t h e f i l l to t h e s t o p e w a l l s f o r l o n g t e r m s t a b i l i t y . 8 . 2 . 1 S t o p e Wa l l S t a b i l i t y T h e g r a p h i c a l p r e s e n t a t i o n o f t h e d i s c o n t i n u i t i e s ( F i g u r e 8 . 1 ) s h o w s t h a t t h e d i s c o n t i n u i t i e s o t h e r t h a n t h e f a u l t i n g a s s o c i a t e d w i t h t h e N o r t h S h e a r p r o d u c e n e a r - o r t h o g o n a l b l o c k s i n t h e s t o p e w a l l s . T h e s e b l o c k s a r e g e n e r a l l y o r i e n t e d w i t h t h e i r l o n g a x e s n e a r - p a r a l l e l to t h e d i p of t h e w a l l s a n d t h e i n t e r m e d i a t e a x e s n e a r - p a r a l l e l t o t h e s t r i k e of t h e w a l l s . T h e l e a s t s i g n i f i c a n t j o i n t s e t p r o v i d e s a r o u g h , w a v y , d i s c o n t i n u o u s , n e a r - h o r i z o n t a l p l a n e of w e a k n e s s . F i g u r e 8 .1 • n of O r i e n t a t i o n of t h e S t o p e s w i t h t n e 191 T h e d i s c o n t i n u i t i e s i s o l a t e b l o c k s t h a t a r e k i n e m a t i c a l l y s t a b l e i n t h e s t r e s s r e l i e v e d z o n e s i n t h e f o o t w a l l o f t h e s t o p e s . In t h e h a n g i n g w a l l , b l o c k s i s o l a t e d b y t h e s e t h r e e s e t s of d i s c o n t i n u i t i e s w i l l b e u n s t a b l e . H o w e v e r , a s o n l y 4 . 5 m e t r e s h e i g h t of s t o p e w a l l w i l l b e e x p o s e d at a n y g i v e n t i m e , t h e e f f e c t s o f t h o s e s t r u c t u r e s o n t h e h a n g i n g w a l l s t a b i l i t y w i l l b e s m a l l . In t h e l o n g t e r m , t h e s u p p o r t p r e s s u r e p r o v i d e d b y t h e b a c k f i l l w i l l e n s u r e t h e s t a b i l i t y of i s o l a t e d b l o c k s . 8 . 2 . 1 . 1 N G I A n a l y s i s It i s s u g g e s t e d b y B a r t o n 4 t h a t a c r i t i c a l v a l u e of Q ( N G I c l a s s i f i c a t i o n ) , f o r w h i c h a g i v e n s p a n w i l l b e s t a b l e , c a n b e c a l c u l a t e d f r o m Q = S p a n 1 . 3 w h e r e Spah - F S p \ a n of e x c a v a t i o n a t w a l l h e i g h t = 4 . 5 m T h e r e f o r e t h e c r i t i c a l r o c k q u a l i t y c a n b e c a l c u l a t e d a s : Q = ( 4 . 5 ) 1 . 5 = 3 . 3 8 o r R M R = 9 l o g e Q + 44 = 55%, i n d i c a t i n g t h a t t h e s t o p e w a l l i n e a c h c u t w i l l b e s t a b l e w h e r e v e r t h e R o c k M a s s R a t i n g e x c e e d s 55%. T h i s i s c o n f i r m e d b y B i e n i a w s k i ' s r e l a t i o n s h i p b e t w e e n R M R a n d s t a n d - u p t ime as d e t a i l e d i n C h a p t e r F o u r . W h e r e t h e N o r t h S h e a r i s w i t h i n 3 m o f t h e h a n g i n g w a l l of t h e s t o p e , t h e r o c k m a s s r a t i n g of t h e s t o p e w a l l s h o u l d b e 192 r e d u c e d to t h e R o c k M a s s R a t i n g o f t h e N o r t h S h e a r i t s e l f . In g e n e r a l , t h e R o c k M a s s R a t i n g o f t h e N o r t h S h e a r _ r a n g e s f r o m 40 to 50 o r i n t h e r a n g e of 0 . 9 to 1.1 f o r t h e N G I I n d e x , Q . U s i n g B a r t o n ' s r e c o m m e n d e d s u p p o r t c h a r t s a n d an E S R of 3 , a d e s i g n p a t t e r n o f 2 . 5 m S p l i t S e t r o c k b o l t s a t a 1.0 m s p a c i n g s h o u l d b e u s e d f o r t e m p o r a r y s u p p o r t d u r i n g t h e e x c a v a t i o n p a r t o f t h e c y c l e . B y c o m p a r i n g B a r t o n ' s a p p r o x i m a t e r e q u i r e d s u p p o r t p r e s s u r e ( 0 . 1 5 M P a to 0 . 2 2 5 M P a ) w i t h t h e r e s u l t s of t h e f i n i t e e l e m e n t a n a l y s i s ( T a b l e 7 . 4 ) , i t i s a p p a r e n t t h a t t h e b a c k f i l l p r o v i d e s m o r e t h a n a d e q u a t e s u p p o r t f o r t h e s t o p e w a l l s o f p r e v i o u s c u t s ( i . e . , f o r l o n g t e r m s t a b i l i t y ) . 8 . 2 . 1 . 2 T h e G o l d e r M e t h o d T h e G o l d e r M e t h o d o f e v a l u a t i n g a c t i v e s t o p e s p a n s l ^ i n v o l v e s t h e u s e o f a m o d i f i e d N G I R o c k m a s s 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 t h e q u a n t i t a t i v e d e f i n i t i o n of t h e a c t i v e s t r e s s c o n d i t i o n s , t h e o r i e n t a t i o n of t h e m a j o r d i s c o n t i n u i t i e s a n d t h e o r i e n t a t i o n o f t h e s p a n to d e t e r m i n e a s t a b i l i t y n u m b e r . T h i s n u m b e r h a s b e e n p l o t t e d a g a i n s t t h e h y d r a u l i c r a d i u s of t h e s p a n f o r a t o t a l o f 55 s p a n s i n d i f f e r e n t s t o p e s i n a r a n g e of s t a b l e to c a v i n g c o n d i t i o n s . T h e r e s u l t i n g p l o t ( F i g u r e 8 . 2 ) d e f i n e s t h e c o n d i t i o n s y i e l d i n g 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 , a n d p o t e n t i a l l y c a v i n g s p a n s . 193 1000.0 100.0 10.0 1.0 0.1 0 A <<> X o fee !§¥> - A 25 5 10 15 20 S H A P E F A C T O R (m) F i g u r e 8 . 2 G r a p h of S t a b i l i t y N u m b e r ( N ) V e r s u s S h a p e F a c t o r ( S ) ( A f t e r G o l d e r ' s ) 1 9 T h e s t a b i l i t y n u m b e r , N , i s d e f i n e d b y t h e p r o d u c t of t h e v a l u e s Q ' , A , B , a n d C . N = Q ' x A x B x C w h e r e Q' = Q ( N G I ) w i t h t h e s t r e s s r e d u c t i o n f a c t o r se t a t 1 . T h e v a r i a b l e A , t h e s t r e s s f a c t o r ( F i g u r e 8 . 3 ) is d e f i n e d a s : A = 0 . 1 1 1(0^/0 - 2 - 1 ) w h e r e = 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 cr- = i n d u c e d s t r e s s a c t i n g p a r a l l e l to t h e s p a n . In s t r e s s r e l i e v e d a r e a s , w h e r e t h e r a t i o of i n t a c t r o c k 194 s t r e n g t h to i n d u c e d s t r e s s e x c e e d s 1 0 , f a i l u r e of i n t a c t r o c k b e t w e e n d i s c o n t i n u i t i e s s h o u l d no t o c c u r . O n l y t h e f a i l u r e a l o n g e x i s t i n g d i s c o n t i n u i t i e s i s l i k e l y a n d t h e r o c k s t r e s s f a c t o r , A , i s se t to 1 . 0 . / / / / / / / / / / / 5-Z o n e of potentfol instability (C 0 5 10 15 2 0 ova, F i g u r e 8 . 3 - G r a p h to D e t e r m i n e t h e R o c k S t r e s s F a c t o r ( A ) ( A f t e r G o l d e r ' s ) 1 9 T h e d i s c o n t i n u i t y o r i e n t a t i o n f a c t o r , B , i s a f a c t o r u s e d to a d j u s t t h e s t a b i l i t y n u m b e r to a l l ow f o r t h e o r i e n t a t i o n of t h e p e r s i s t e n t s t r u c t u r e s i n t h e r o c k m a s s r e l a t i v e to t h e s p a n b e i n g a n a l y s e d . V a l u e s f o r v a r i o u s i n t e r s e c t i o n a n g l e s a r e g i v e n i n F i g u r e 8 . 4 . 195 ORIENTATION OF RO6F FAGTOR B ORIENTATION OF W A L L 1.0 0.5 F i g u r e 8.4 - 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 ( B ) ( A f t e r G o l d e r ' s ) 1 9 196 T h e f a c t o r C is d e p e n d e n t u p o n t h e o r i e n t a t i o n of t h e s p a n in q u e s t i o n . It i s d e f i n e d b y C = 8 - 7 c o s e w h e r e 6 = t h e a n g l e of d i p f r o m h o r i z o n t a l i n d e g r e e s . T h e h y d r a u l i c r a d i u s w h i c h i s p l o t t e d a g a i n s t t h e s t a b i l i t y n u m b e r i n F i g u r e 8.2 i s d e f i n e d as a s h a p e f a c t o r : S = A r e a of S p a n P e r i m e t e r of S p a n T h i s G o l d e r M e t h o d of a n a l y s i s h a s b e e n p e r f o r m e d f o r t h e s t o p e w a l l s f o r t h e c a s e of t h e N o r t h S h e a r no t a f f e c t i n g t h e s t o p e w a l l s a n d f o r t h e c a s e of t h e N o r t h S h e a r w i t h i n t h e a r e a o f i n f l u e n c e of t h e s t o p e w a l l . T h e r e s u l t s of t h e s e a n a l y s e s a r e s u m m a r i z e d i n T a b l e 8 . 1 . NORTH SHEAR CONDITION Q' A B C N HEIGHT L E N G T H S STABILITY (m) (m) Not present Single Cut 33 1.0 0.3 6 60 4.5 300.0 2.2 Stable Not present 1/4 Stope Height 33 1.0 0.3 6 60 Not present 1/2 Stope Height 33 1.0 0.3 6 60 30.0 300.0 13.6 Pot. Unstable Not present Full Stope Height 33 1.0 0.3 6 60 60.0 300.0 25.0 Pot. Caving 120.0 300.0 42.9 Pot. Caving Present Single Cut 1.0 1.0 0.3 6 1.8 300.0 Present 1/4 Stope Height 1.0 1.0 0.3 6 1.8 4.5 2.2 Pot. Unstable Present 1/2 Stope Height 1.0 1.0 0.3 6 1.8 30.0 300.0 13.6 Pot. Caving Present Full Stope Height 1.0 1.0 0.3 6 1.8 60.0 300.0 25.0 Pot. Caving 120.0 300.0 42.9 Pot. Caving T A B L E 8.1 Results of Golder Analysis on Stope Walls 8 . 2 . 1 . 3 D i s c u s s i o n on S t a b i l i t y o f S t o p e Wa l l s 198 T h e r e s u l t s of t h e t h r e e m e t h o d s of a n a l y s i s c l e a r l y i n d i c a t e t h a t t h e s t o p e w a l l s e x p o s e d i n e a c h i n d i v i d u a l c u t ( 4 . 5 m e t r e s ) w i l l b e s t a b l e f o r t h e d u r a t i o n of t h e c y c l e w i t h o u t a d d i t i o n a l s u p p o r t w h e r e t h e y a r e no t a f f e c t e d b y t h e N o r t h S h e a r . H o w e v e r , p o t e n t i a l i n s t a b i l i t y o f t h e h a n g i n g w a l l o f t h e s t o p e w i l l e x i s t w h e r e i t i s a f f e c t e d b y t h e N o r t h S h e a r . B a s e d u p o n B a r t o n ' s r e c o m m e n d e d s u p p o r t , i t a p p e a r s t h a t a d e s i g n of 2 . 5 m e t r e S p l i t S e t r o c k b o l t s a t a 1.0 m e t r e s p a c i n g w i l l p r o v i d e a d e q u a t e t e m p o r a r y s u p p o r t f o r t h e d u r a t i o n of e a c h c u t - a n d - f i l l c y c l e . In t h e l o n g e r t e r m , t h e c o n d i t i o n s i n t h e s t o p e w a l l s w o u l d r a n g e f r o m p o t e n t i a l l y u n s t a b l e to p o t e n t i a l c a v i n g c o n d i t i o n s i f i t w e r e n o t f o r t h e s u p p o r t p r e s s u r e p r o v i d e d b y t h e b a c k f i l l . 8 . 2 . 2 S t o p e R o o f S t a b i l i t y 8 . 2 . 2 . 1 S t r u c t u r a l S t a b i l i t y A s d i s c u s s e d i n S e c t i o n 8 . 1 . 1 . 1 , t h e m a j o r s e t s of d i s c o n t i n u i t i e s a r e n e a r o r t h o g o n a l to e a c h o t h e r a n d to t h e g e n e r a l o r i e n t a t i o n of t h e s t o p e s . In t h e s t o p e w a l l s t h i s c o n f i g u r a t i o n i s g e n e r a l l y k i n e m a t i c a l l y s t a b l e . In t h e s t o p e r o o f s t r u c t u r a l f a i l u r e a l o n g t h e s e p l a n e s i s k i n e m a t i c a l l y p o s s i b l e . H o w e v e r , i n t h e s t o p e r o o f , t h e i n c r e a s e i n s t r e s s a c r o s s 199 J o i n t S e t A d u e to t h e e x c a v a t i o n of t h e s t o p e w i l l i n c r e a s e t h e r e s i s t a n c e to s l i d i n g a l o n g t h i s p l a n e , a n d t h e r e f o r e h a v e a s t a b i l i z i n g e f f e c t . In o r d e r to a s s e s s t h e s t r u c t u r a l s t a b i l i t y of t h e s t o p e roo f w h e n t h e ma jo r p r i n c i p a l s t r e s s i s l e s s t h a n o n e - f i f t h of t h e 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 , e m p i r i c a l d e s i g n m e t h o d s c a n b e u s e d . 8 . 2 . 2 . 2 N G I A n a l y s i s U s i n g B a r t o n ' s m e t h o d of a s s e s s i n g a c r i t i c a l v a l u e of Q f o r w h i c h a g i v e n s p a n w i l l b e s t a b l e , t h e s t a b i l i t y o f t h e s t o p e r o o f c a n b e a s s e s s e d f o r s t o p e w i d t h s of 3 m , 6 m , 10 m , a n d 20 m ( T a b l e 8 . 2 ) . T A B L E 8 . 2 S u m m a r y of C r i t i c a l R o c k M a s s R a t i n g f o r a S t a b l e Roo f of a G i v e n S p a n S P A N Q C R I T I C A L R M R C R I T I C A L 3 m 1 44% 6 m 5 . 6 60% 10 m 2 0 . 1 71% 20 m 1 1 2 . 6 86% 200 G i v e n a R o c k M a s s R a t i n g of 75% i n t h e f o o t w a l l r o c k s , a s p a n o f u p to 13 m s h o u l d b e s t a b l e . H o w e v e r , w h e r e t h e N o r t h S h e a r i s e x c a v a t e d i n t h e s t o p e , a R o c k M a s s R a t i n g o f 45% s h o u l d b e u s e d f o r d e s i g n p u r p o s e s . In t h i s c a s e , e v e n a 3 m e t r e s p a n i s o n l y m a r g i n a l l y s t a b l e . T h e s e v a l u e s c o m p a r e w e l l w i t h B i e n i a w s k i ' s e s t i m a t e of s t a n d - u p t ime f o r u n s u p p o r t e d r o c k s w h e n t h e r e q u i r e d s t a n d - u p t ime of t h r e e w e e k s i s c o n s i d e r e d . W h e r e t h e s p a n of t h e s t o p e r o o f e x c e e d s 13 m a n d c o n s i s t s e n t i r e l y of f o o t w a l l r o c k s , B a r t o n ' s r e c o m m e n d e d s u p p o r t c o n s i s t s o f g r o u t e d , u n t e n s i o n e d r o c k d o w e l s a t a s p a c i n g o f 1 .5 m to 2 m . H o w e v e r , as t h e c y c l e t ime i s a n t i c i p a t e d to b e i n t h e o r d e r o f t h r e e w e e k s , 2 . 5 m S p l i t S e t s c a n b e s u b s t i t u t e d f o r g r o u t e d d o w e l s . B e c a u s e t h e N o r t h S h e a r i s o f l i m i t e d w i d t h , w h e r e i t i s e x p o s e d i n t h e r o o f , o n l y S p l i t S e t s n e e d b e i n s t a l l e d a t a s p a c i n g o f 1 .0 m e t r e s o v e r t h e e n t i r e r o o f . 8 . 2 . 2 . 3 T h e G o l d e r M e t h o d A n a l y s i s of t h e s t o p e r o o f b y t h e G o l d e r M e t h o d , as s u m m a r i z e d i n T a b l e 8 . 3 , c o n f i r m s t h a t t h e r o o f w i l l b e s t a b l e w i t h s p a n s of u p to 13 m w h e n t h e ma jo r p r i n c i p a l s t r e s s i s l e s s t h a n o n e - f i f t h of t h e 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 of t h e r o c k s a n d t h e N o r t h S h e a r i s n o t e x p o s e d i n t h e r o o f . W h e r e 201 T A B L E 8 . 3 R e s u l t s of G o l d e r A n a l y s i s o n S t o p e R o o f S p a n Q' A B C N S 3 m 33 1 1.0 1 33 1 .49 S T A B L E 6 m 33 1 1.0 1 33 2 . 9 4 S T A B L E 10 m 33 1 1.0 1 33 4 . 8 4 S T A B L E 20 m 33 1 1.0 1 33 9 . 3 8 P O T . U N S T . 3 m 33 0 .6 1.0 1 20 1.49 S T A B L E 6 m 33 0 . 6 1.0 1 20 2 . 9 4 S T A B L E 10 m 33 0 . 6 1.0 1 20 4 . 8 4 S T A B L E 20 m 33 0 . 6 1.0 1 20 9 . 3 8 P O T . U N S T . 3 m 33 0 . 4 1.0 1 13 1 .49 S T A B L E 6 m 33 0 . 4 1.0 1 13 2 . 9 4 S T A B L E 10 m 33 0 . 4 1.0 1 13 4 . 8 4 P O T . U N S T . 20 m 33 0 . 4 1.0 1 13 9 . 3 8 P O T . U N S T . 3 m 33 0 . 2 1.0 1 6 . 6 1 .49 S T A B L E 6 m 33 0 . 2 1.0 1 6 . 6 2 . 9 4 P O T . U N S T . 10 m 33 0 . 2 1.0 1 6 . 6 4 . 8 4 P O T . U N S T . 20 m 33 0 .2 1.0 1 6 . 6 9 . 3 8 P O T . U N S T . 3 m 1 1 1.0 1 1 1 .49 S T A B L E 6 m 1 1 1.0 1 1 2 . 9 4 P O T . U N S T . 10 m 1 1 1.0 1 1 4 . 8 4 P O T . U N S T . 20 m 1 1 1.0 1 1 9 . 3 8 P O T . U N S T . 202 t h e N o r t h S h e a r i s e x p o s e d i n t h e r o o f , t h e r o o f w i l l b e s t a b l e o n l y w h e r e t h e s p a n i s l e s s t h a n 3 m a n d t h e m a j o r p r i n c i p a l s t r e s s i s l e s s t h a n o n e - t e n t h of t h e 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 of t h e r o c k . 8 . 1 . 2 . 4 D i s c u s s i o n o n S t a b i l i t y of T e m p o r a r y S t o p e R o o f P r e l i m i n a r y a n a l y s e s , u s i n g t h e N G I C l a s s i f i c a t i o n s y s t e m a n d B a r t o n ' s R e c o m m e n d e d s u p p o r t a n d u s i n g t h e G o l d e r M e t h o d , i n d i c a t e t h a t i n i t i a l l y t h e r o o f o f t h e s t o p e w i l l b e s t a b l e w i t h s p a n s l e s s t h a n 13 m i n w i d t h i n t h e f o o t w a l l r o c k s a n d 3 m i n w i d t h w h e r e t h e N o r t h S h e a r i s e x p o s e d i n t h e r o o f o f t h e c u t . H o w e v e r , as m i n i n g p r o c e e d s , t h e m a j o r p r i n c i p a l s t r e s s a c t i n g o n t h e r o c k s i n t h e r o o f o f e a c h c u t w i l l b e l a r g e r t h a n i n t h e r o o f o f t h e p r e v i o u s c u t . A f t e r a n u m b e r of c u t s i n e a c h s t o p e t h e s t r e s s i n t h e r o o f o f t h e c u t w i l l h a v e i n c r e a s e d s u f f i c i e n t l y to r e d u c e t h e c o n d i t i o n of t h e r o o f to p o t e n t i a l l y u n s t a b l e . T h i s i m p l i e s t h a t t h e r o c k w i l l h a v e to b e r e i n f o r c e d to m a i n t a i n a s t a b l e r o o f , e v e n f o r t h e m i n i m u m s t o p e w i d t h of 3 m , b e f o r e t h e f u l l h e i g h t o f t h e s t o p e i s r e a c h e d . A t t h e s e l e v e l s of s t r e s s , 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 m u c h m o r e l i k e l y t h a 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 a n d t h e s t a b i l i t y o f t h e roo f o f t h e c u t i s m o r e a c c u r a t e l y d e f i n e d u s i n g t h e m a j o r p r i n c i p a l s t r e s s c o n d i t i o n s a n d a f a i l u r e c r i t e r i o n . In o t h e r w o r d s , s i l l p i l l a r s t r e n g t h s h o u l d b e e v a l u a t e d r a t h e r t h a n t h e roo f o f t h e c u t . 203 8 . 3 S I L L P I L L A R D E S I G N In o r d e r to d e f i n e t h e m i n i m u m s a f e w i d t h o f t h e s i l l p i l l a r , t h e m i n i m u m s e p a r a t i o n o f t h e s t o p e s , t h e a n a l y s i s m u s t b e t w o - f o l d f o r t h e M c L e l l a n M i n e . F i r s t t h e s t r u c t u r a l i n t e g r i t y o f t h e p i l l a r m u s t b e i n v e s t i g a t e d w i t h r e s p e c t to t h e g e o l o g i c a l d i s c o n t i n u i t i e s . T h e n t h e c o n d i t i o n s i n t h e p i l l a r m u s t b e a n a l y z e d w i t h r e s p e c t to s t r e s s f a i l u r e . 8 . 3 . 1 S t r u c t u r a l A n a l y s i s T h e s t r u c t u r a l i n t e g r i t y of t h e p i l l a r c a n b e i n v e s t i g a t e d r e l a t i v e l y q u i c k l y b y m e a n s o f g e o m e t r i c a n a l y s i s to d e t e r m i n e i f t h e p i l l a r i s t r a n s e c t e d b y d i s c o n t i n u i t i e s . If s u c h t r a n s e c t i o n c a n o c c u r t h e p i l l a r m a y f a i l u n d e r l o w s t r e s s c o n d i t i o n s . H o w e v e r , i f t h e p i l l a r i s no t t r a n s e c t e d b y d i s c o n t i n u i t i e s , i t s s t r e n g t h c a n s u r p a s s t h a t o f i n t a c t l a b o r a t o r y s a m p l e s u n d e r c e r t a i n s t r e s s c o n d i t i o n s . A s s h o w n i n F i g u r e 8 . 5 , t h e d i s c o n t i n u i t i e s m a p p e d at t h e M c L e l l a n M i n e a r e n e a r - o r t h o g o n a l to t h e o r i e n t a t i o n of t h e s i l l p i l l a r . U n d e r c o m p r e s s i v e s t r e s s c o n d i t i o n s , t h e s i l l p i l l a r i s s t r u c t u r a l l y s t a b l e a t v i r t u a l l y a n y w i d t h . 8 . 3 . 2 S t r e s s A n a l y s i s T o a s s e s s t h e p i l l a r s t r e n g t h w i t h r e s p e c t to t h e s t r e s s 204 F i g u r e 8.5 S t r u c t u r a l A n a l y s i s of t h e S i l l P i l l a r c o n d i t i o n s i n t h e p i l l a r , a f a i l u r e c r i t e r i o n m u s t b e a d o p t e d . O f t h e m a n y p i l l a r s t r e n g t h f o r m u l a e , a n d / o r f a i l u r e c r i t e r i a d i s c u s s e d i n r o c k m e c h a n i c s l i t e r a t u r e , o n l y t h e c r i t e r i o n of H o e k a n d B r o w n ^ 3 a s s e s s e s t h e p i l l a r s t r e n g t h o n t h e b a s i s of t h e s t r e s s c o n d i t i o n s i n t h e p i l l a r , t h e i n t a c t r o c k s t r e n g t h , a n d t h e b r o k e n n a t u r e of t h e r o c k . T h i s f a i l u r e c r i t e r i o n , o\ = 03 + \[macaj, + s<Tc^ 205 a s s u m e s t h a t a t f a i l u r e t h e o v e r a l l s t r e n g t h of a p i l l a r i s a p p r o x i m a t e l y e q u a l to t h e a v e r a g e s t r e s s a c r o s s t h e c e n t r e of t h e p i l l a r . C o u p l e d w i t h t h e r e s u l t s of t h e n u m e r i c a l m o d e l l i n g a n d t h e r o c k m a s s c h a r a c t e r i z a t i o n , i n c l u d i n g t h e l a b o r a t o r y t e s t i n g , t h i s f a i l u r e c r i t e r i o n p r o v i d e s a r e l a t i v e l y q u i c k a s s e s s m e n t of t h e s t r e n g t h of e a c h f i n i t e e l e m e n t u n d e r v a r i o u s s t r e s s c o n d i t i o n s . A n a v e r a g e p i l l a r s t r e n g t h c a n t h e n b e e s t i m a t e d f r o m t h e r e s u l t s o f t h e s e a n a l y s e s . 8 . 3 . 2 . 1 N u m e r i c a l A n a l y s e s A s d i s c u s s e d i n C h a p t e r 7 , s e v e r a l f i n i t e e l e m e n t a n a l y s e s w e r e c o m p l e t e d to i n v e s t i g a t e t h e s e n s i t i v i t y o f t h e m o d e l to t h e e n g i n e e r i n g p r o p e r t i e s o f t h e b a c k f i l l a n d to s t u d y t h e e f f e c t s o f r e i n f o r c i n g t h e d r a i n a g e t u n n e l i n t h e s i l l p i l l a r . A d d i t i o n a l r u n s o f t h e m o d e l w e r e c o m p l e t e d to a n a l y z e t h e s t a b i l i z i n g e f f e c t s o f c o n s o l i d a t i n g t h e f i l l , i n t h e v i c i n i t y of t h e s i l l p i l l a r , w i t h c e m e n t . T h e e n g i n e e r i n g p a r a m e t e r s u s e d f o r t h e r o c k a n d t h e u n c o n s o l i d a t e d f i l l a r e : (1) F R E S H R O C K ( B e l o w 1400 m E l e v a t i o n ) E = 50 G P a \ * = 0 . 2 1 p = 2960 K g / m 3 (2) W E A T H E R E D R O C K ( A b o v e 1400 m E l e v a t i o n ) E = 10 G P a V = 0 . 2 1 £ = 2960 K g / m 3 206 (3) U N C O N S O L I D A T E D F I L L E = 6 . 9 0 G P a •V = 0 . 3 5 p_ = 2000 K g / m 3 In a d d i t i o n , t h e e n g i n e e r i n g p a r a m e t e r s u s e d to m o d e l t h e e f f e c t s of r e i n f o r c i n g t h e d r a i n a g e t u n n e l , f o r c o n s o l i d a t i n g t h e l o w e r 15 m o f t h e u p p e r s t o p e b y g r o u t i n g a t a l a t e r d a t e a n d f o r u s i n g c e m e n t e d f i l l i n t h e u p p e r 15 m o f t h e l o w e r s t o p e a r e : E = 10 G P a V = 0 . 3 5 o = 2000 K g / m 3 e x c e p t i n t h e d r a i n a g e t u n n e l w h e r e : e = o T a b l e 8 . 4 s u m m a r i z e s t h e c o n d i t i o n s m o d e l l e d i n e a c h r u n of t h e f i n i t e e l e m e n t a n a l y s i s . C o n t o u r s o f t h e s t r e s s c o n d i t i o n s i n t h e s i l l p i l l a r f o r f i v e s t a g e s of t h e e x c a v a t i o n i n e a c h r u n of t h e m o d e l a r e g i v e n i n A p p e n d i x X I X . T h e s t r e s s c o n d i t i o n s i n e a c h e l e m e n t o f t h e p i l l a r a r e g i v e n i n A p p e n d i x X X . 207 T A B L E 8 . 4 S u m m a r y of C o n d i t i o n s M o d e l l e d R U N D R A I N A G E T U N N E L U P P E R STOPE LOWER STOPE N o S u p p o r t S u p p o r t N o G r o u t N o G r o u t C e m e n t C e m e n t 6 X X X X X X 7 X X X X X X 8 X X X X X X 10 X X X X X X 9 X X X X X X 8 . 3 . 2 . 2 H o e k ' s F a i l u r e C r i t e r i o n To d e t e r m i n e i f t h e s t r e s s s e s i n t h e s i l l p i l l a r w i l l c a u s e f a i l u r e a t a n y g i v e n s t a g e of t h e m i n i n g , H o e k ' s f a i l u r e c r i t e r i o n w a s a d o p t e d . T h e e m p i r i c a l r e l a t i o n s h i p d e v e l o p e d b y H o e k a n d B r o w n i s d e f i n e d b y : ° i s = °3 + vWco-3 + scr c 2 w h e r e 03 i s t h e m i n o r p r i n c i p a l s t r e s s as d e f i n e d b y t h e n u m e r i c a l m o d e l l i n g , i s 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 208 a s d e f i n e d b y t h e l a b o r a t o r y t e s t i n g a n d m a n d s a r e t h e m a t e r i a l c o n s t a n t s e s t i m a t e d i n C h a p t e r F o u r . A s c o n c l u d e d i n C h a p t e r F o u r , t h e m a t e r i a l c o n s t a n t s f o r t h e r o c k i n t h e s i l l p i l l a r a r e e s t i m a t e d a t : m = 7 . 5 s = 0 .1 B e c a u s e o f t h e l i m i t e d t h i c k n e s s o f t h e N o r t h S h e a r i n t h e v i c i n i t y of t h e s i l l p i l l a r a n d i t s p e r p e n d i c u l a r i t y to t h e ma jo r p r i n c i p a l s t r e s s , i t i s no t e x p e c t e d to h a v e a s i g n i f i c a n t e f f e c t o n t h e s t r e n g t h of t h e p i l l a r . T h e 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 of i n t a c t r o c k i n t h e s i l l p i l l a r i s e s t i m a t e d at 92 M P a , t h e i n t a c t s t r e n g t h o f t h e t u f f a c e o u s s e d i m e n t s . F o r t h e c o n s o l i d a t e d f i l l a n d t h e r e i n f o r c e d d r a i n a g e t u n n e l , t h e m a t e r i a l c o n s t a n t s a n d t h e 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 w e r e a s s e s s e d a s : m = 10 s = 1.0 ( u n f r a c t u r e d ) U c s = 50 M P a 8 . 3 . 2 . 3 P i l l a r S t r e n g t h A n a l y s i s A s o u t l i n e d i n t h e p r e c e d i n g s e c t i o n s , t h e p i l l a r s t r e n g t h w a s a s s e s s e d a t v a r i o u s s t a g e s o f t h e f u t u r e m i n i n g u s i n g H o e k a n d B r o w n ' s f a i l u r e c r i t e r i o n . T h e s t r e n g t h o f e a c h e l e m e n t i n t h e p i l l a r w a s c a l c u l a t e d b y u s i n g H o e k a n d B r o w n ' s f o r m u l a . 209 T h e a v e r a g e p i l l a r s t r e n g t h w a s t h e n c a l c u l a t e d u s i n g : 1) t h e s t r e n g t h o f e a c h e l e m e n t 2 ) t h e a v e r a g e p i l l a r s t r e s s c o n d i t i o n s i n t h e p i l l a r F i n a l l y , t h e s t r e n g t h : s t r e s s r a t i o , a m e a s u r e o f t h e f a c t o r o f s a f e t y , w a s c a l c u l a t e d f o r : 1) e a c h e l e m e n t i n t h e p i l l a r , 2 ) t h e o v e r a l l p i l l a r b y a v e r a g i n g t h e s t r e n g t h : s t r e s s r a t i o f o r e a c h e l e m e n t , a n d 3 ) t h e o v e r a l l p i l l a r b y a v e r a g i n g t h e p i l l a r s t r e n g t h of e a c h e l e m e n t a n d c o m p a r i n g i t t o t h e a v e r a g e m a j o r p r i n c i p a l s t r e s s 4 ) t h e o v e r a l l p i l l a r u s i n g t h e a v e r a g e s t r e s s c o n d i t i o n s t o c a l c u l a t e a n a v e r a g e p i l l a r s t r e n g t h a n d c o m p a r i n g t h i s s t r e n g t h to t h e a v e r a g e m a j o r p r i n c i p a l s t r e s s . T h e r e s u l t s o f t h e s e a n a l y s e s a r e g i v e n i n A p p e n d i x X X I . M e t h o d 3 g i v e n a b o v e y i e l d e d t h e m o s t c o n s e r v a t i v e r e s u l t s . H o w e v e r , b e c a u s e o f t h e a d a p t a b i l i t y o f t h e c u t - a n d - f i l l m i n i n g m e t h o d , t h i s d e s i g n i s p r e l i m i n a r y i n n a t u r e a n d t h e l e a s t c o n s e r v a t i v e v a l u e s , M e t h o d 2 , h a v e b e e n u s e d f o r d e s i g n p u r p o s e s . T h e r e s u l t s f r o m t h e M e t h o d 2 a n a l y s i s a r e s u m m a r i z e d i n F i g u r e 8 . 6 . 8 . 3 . 3 D i s c u s s i o n of R e s u l t s T h e c u r v e s o f t h e v a r i o u s a n a l y s e s p l o t t e d o n F i g u r e 8 .6 s h o w a g e n e r a l d e c r e a s e i n t h e s t r e n g t h : s t r e s s r a t i o w i t h an 210 i n c r e a s e i n p i l l a r w i d t h . H o w e v e r , t h e e f f e c t s of t h e c o n s o l i d a t e d b a c k f i l l c a n b e s e e n i n R u n s 8 a n d 9 b e t w e e n p i l l a r w i d t h s of 2 2 . 5 a n d 1 8 . 5 m . R u n 6 , r e p r e s e n t i n g t h e m o d e l w i t h no s u p p o r t i n t h e d r a i n a g e t u n n e l a n d n o n - c o n s o l i d a t e d f i l l s h o w s t h a t t h e s t r e n g t h : s t r e s s r a t i o o f t h e p i l l a r w i l l b e l e s s t h a n u n i t y i f t h e l o w e r s t o p e i s e x c a v a t e d u p to t h e b o t t o m of t h e d r a i n a g e t u n n e l . F o r t h i s c o n d i t i o n , t h e s i l l p i l l a r m u s t b e a t l e a s t 11 m e t r e s i n w i d t h to m a i n t a i n a s t r e n g t h : s t r e s s r a t i o of 1 . 5 . R e i n f o r c i n g t h e d r a i n a g e t u n n e l b y l i n i n g i t w i t h c o n c r e t e w i l l l i k e l y o n l y r e d u c e t h e s a f e p i l l a r w i d t h to 1 0 . 5 m e t r e s . I f t h e l o w e r 16 m o f t h e u p p e r s t o p e i s g r o u t e d b e f o r e t h e l o w e r s t o p e r e a c h e s a h e i g h t o f 60 m e t r e s , i t i s p o s s i b l e t h a t t h e s i l l p i l l a r w i d t h c a n b e r e d u c e d t o 9 . 5 m e t r e s a n d i f t h e u p p e r 16 m of t h e l o w e r s t o p e i s f i l l e d w i t h c e m e n t e d f i l l , t h e s i l l p i l l a r may p o s s i b l y b e r e d u c e d to a w i d t h of 8 . 5 m e t r e s . H o w e v e r , t h e n u m e r i c a l a n a l y s e s o f t h e s e c o n d i t i o n s i n d i c a t e s t h a t f a i l u r e may t a k e p l a c e i n t h e c o n s o l i d a t e d f i l l p r i o r to f a i l u r e i n t h e s i l l p i l l a r . T h e r e f o r e t h e c o n s o l i d a t e d f i l l w o u l d p r o v i d e l e s s s u p p o r t to t h e s t o p e w a l l s t h a n p r e d i c t e d a n d t h e s i l l p i l l a r w o u l d b e s u b j e c t e d to l a r g e r m a j o r p r i n c i p a l s t r e s s e s . In a d d i t i o n to t h e s e c o n s i d e r a t i o n s , t h e e f f e c t o f t h e c o n f i n e m e n t o f f e r e d b y t h e e n d s of t h e s i l l p i l l a r m u s t b e c o n s i d e r e d , e s p e c i a l l y i f a l a r g e r p i l l a r w i d t h c a n b e l e f t t o w a r d s t h e t w o e n d s of t h e k n o w n d e p o s i t . T h i s w o u l d 211 i n c r e a s e t h e l o a d c a r r i e d a t t h e e x t r e m i t i e s of t h e p i l l a r a n d r e d u c e t h e s t r e s s e s i n t h e c e n t r a l p o r t i o n of t h e p i l l a r . O < cn CO 00 UJ or !— oo h-CD ~ZL UJ or 1— CO 3.0 - r 2.5 H 2.0 .5 A .0 0.5 H -o RUN NO. 9—»*•/ A/ f /fT- R U N NO. 8 / ^WRUN NO. 7 4 RUN NO. 6 0 0 10 2 0 3 0 PILLAR WIDTH (m) F i g u r e 8.6 - S t r e n g t h R a t i o v s . P i l l a r W i d t h f o r t h e S i l l P i l l a r a t t h e M c L e l l a n S i t e 212 8 . 4 C O N C L U S I O N S B a s e d u p o n t h e c h a r a c t e r i z a t i o n of t h e r o c k m a s s a n d a n a l y s e s c o m p l e t e d u s i n g t h e N G I A n a l y s i s a n d t h e G o l d e r M e t h o d , i t i s a p p a r e n t t h a t l i t t l e to n o r o c k r e i n f o r c e m e n t w i l l b e r e q u i r e d to s u p p o r t t h e w a l l s of e a c h c u t i n t h e s t o p e f o r t h e d u r a t i o n of t h e c u t c y c l e . T h e f o o t w a l l o f t h e s t o p e w i l l l i k e l y n o t r e q u i r e a n y r e i n f o r c e m e n t d u r i n g t h e l i f e of t h e m i n e . T h e h a n g i n g w a l l w i l l l i k e l y r e q u i r e s u p p o r t o n l y w h e r e i t i s a f f e c t e d b y t h e N o r t h S h e a r . W h e r e v e r t h e N o r t h S h e a r f o r m s t h e H a n g i n g Wal l o f t h e s t o p e o r i s w i t h i n 3 m o f t h e s t o p e , i t i s r e c o m m e n d e d t h a t 2 . 5 m e t r e l o n g S p l i t S e t s b e i n s t a l l e d a t a 1.0 m e t r e s p a c i n g . T h e s u p p o r t p r e s s u r e p r o v i d e d b y t h e b a c k f i l l s h o u l d b e a d e q u a t e to p r o v i d e l o n g t e r m s t a b i l i t y o f t h e s t o p e w a l l s . T h e s t a b i l i t y o f t h e r o o f o f e a c h c u t i s d e p e n d e n t n o t o n l y o n t h e r o c k q u a l i t y b u t a l s o u p o n t h e w i d t h o f t h e s t o p e f o r e a c h c u t . W h e r e t h e r o o f o f t h e c u t i s n o t a f f e c t e d b y t h e N o r t h S h e a r a n d t h e s p a n i s 10 m e t r e s o r l e s s , p a t t e r n b o l t i n g w i l l l i k e l y n o t b e r e q u i r e d . W h e r e t h e s p a n i s g r e a t e r t h a n 10 m e t r e s o r t h e r o o f o f t h e c u t i s a f f e c t e d b y t h e N o r t h S h e a r , 2 . 5 m e t r e l o n g S p l i t S e t s s h o u l d b e i n s t a l l e d o n a 1.0 m e t r e s p a c i n g . T h e r e s u l t s of t h 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 t h a t t h e r o o f o f e a c h c u t w i l l b e m a r g i n a l l y s t a b l e i f r e i n f o r c e d as s u g g e s t e d 213 a b o v e . H o w e v e r , w h e n t h e d i s t a n c e f r o m t h e r o o f of t h e l o w e r s t o p e to t h e d r a i n a g e t u n n e l i s l e s s t h a n 30 m e t r e s , i t i s r e c o m m e n d e d t h a t w e l d e d w i r e m e s h b e i n s t a l l e d w i t h 2 . 5 m e t r e l o n g s p l i t - s e t s at a s p a c i n g of 1.0 m e t r e . If c o n t r o l l e d b l a s t i n g t e c h n i q u e s a r e u s e d , d i l u t i o n of t h e m i n e d o r e b y t h e w a s t e r o c k f r o m t h e s t o p e w a l l s i s a n t i c i p a t e d to b e l e s s t h a n 5% w h e r e t h e w a l l s a r e no t a f f e c t e d b y t h e N o r t h S h e a r . W h e r e t h e w a l l s a r e a f f e c t e d b y t h e N o r t h S h e a r , d i l u t i o n may b e as h i g h as 10%. T h e m i n i m u m p i l l a r w i d t h , d e f i n e d as t h e m i n i m u m s e p a r a t i o n o f t h e s t o p e s , a p p e a r s to b e i n t h e o r d e r o f 11 m e t r e s to m a i n t a i n a s t r e n g t h : s t r e s s r a t i o of 1 .5 a n d 8 . 5 m e t r e s to m a i n t a i n a s t r e n g t h : s t r e s s s r a t i o o f 1 . 0 . If r e m e d i a l m e a s u r e s s u c h a s r e i n f o r c i n g t h e d r a i n a g e t u n n e l i n t h e s i l l p i l l a r , g r o u t i n g t h e l o w e r 16 m e t r e s of f i l l i n t h e u p p e r s t o p e a n d / o r u s i n g c e m e n t e d f i l l i n t h e u p p e r 16 m e t r e s o f t h e l o w e r s t o p e a r e u n d e r t a k e n , t h e m i n i m u m s a f e p i l l a r w i d t h c o u l d l i k e l y b e r e d u c e d . H o w e v e r , t h e l o a d - c a r r y i n g c a p a c i t y of t h e c o n s o l i d a t e d f i l l i s q u e s t i o n a b l e a n d t h e s e c o n d i t i o n s t h e r e f o r e c a n n o t b e a n a l y z e d a c c u r a t e l y w i t h t h e c u r r e n t s t a t e of t h e a r t . I t i s a n t i c i p a t e d t h a t t h e m a x i m u m d e c r e a s e i n t h e p i l l a r w i d t h w i t h r e m e d i a l m e a s u r e s w o u l d b e i n t h e o r d e r of 2 . 0 m e t r e s to 2 . 5 m e t r e s . It i s t h e r e f o r e c o n s i d e r e d u n l i k e l y t h a t t h e i n c r e a s e d r e v e n u e f r o m a d d i t i o n a l o r e r e c o v e r y w o u l d e x c e e d t h e c o s t o f t h e s e r e m e d i a l m e a s u r e s . I t i s t h e r e f o r e c o n c l u d e d t h a t t h e m i n i m u m s a f e p i l l a r w i d t h 214 i s 1 1 . 0 m e t r e s . H o w e v e r , i f a r o c k m e c h a n i c s d a t a a c q u i s i t i o n p r o g r a m i s i m p l e m e n t e d e a r l y i n t h e m i n e l i f e , t h e a d d i t i o n a l d a t a w i l l e n a b l e a m o r e a c c u r a t e e s t i m a t e of t h e r e s p o n s e of t h e f i l l a n d t h e p i l l a r to t h e m i n i n g . T h i s w o u l d l i k e l y a l l o w a d e s i g n f o r a s t r e n g t h : s t r e s s r a t i o o f 1.0 a n d e f f e c t i v e l y r e d u c e t h e m i n i m u m s a f e p i l l a r w i d t h . E x t r a p o l a t i o n o f t h e d a t a to a s t r e n g t h : s t r e s s r a t i o of 1 .0 i n d i c a t e s t h a t a s i l l p i l l a r i n t h e o r d e r of 6 m e t r e s to 9 m e t r e s w i d e w o u l d m a i n t a i n s a f e w o r k i n g c o n d i t i o n s i n t h e l o w e r s t o p e . C H A P T E R 9 S U M M A R Y A N D C O N C L U S I O N S 216 9 . 1 M I N I N G E N V I R O N M E N T T h e g o l d - b e a r i n g o r e a t t h e M c L e l l a n M i n e e x i s t s i n a n e a r v e r t i c a l , t h i n d e p o s i t o f i r r e g u l a r g r a d e a n d t h i c k n e s s a n d l o c a l l y o f i r r e g u l a r o r i e n t a t i o n e x t e n d i n g f r o m s u r f a c e to d e p t h s g r e a t e r t h a n 370 m . A l t h o u g h t h e h o s t r o c k s a r e g e n e r a l l y o f a r e l a t i v e l y h a r d , c o m p e t e n t n a t u r e t h e N o r t h S h e a r c o u l d c a u s e h i g h d i l u t i o n f r o m a h i g h , e x p o s e d h a n g i n g w a l l . It i s t h e r e f o r e c o n c l u d e d t h a t t h e e n v i r o n m e n t a t t h e M c L e l l a n M i n e i s b e s t s u i t e d to t h e c u t - a n d - f i l l m i n i n g m e t h o d w h e r e t h e s t o p e w a l l s w i l l b e e x p o s e d o n l y f o r s h o r t l i f t s f o r s h o r t p e r i o d s o f t i m e . In a d d i t i o n t h i s m e t h o d i s m o r e a m e n a b l e to v a r i a t i o n s i n t h i c k n e s s a n d g r a d e t h a n e i t h e r s h r i n k a g e o r o p e n s t o p i n g m e t h o d s . 9 . 2 G E O L O G Y T h e h o s t r o c k s s u r r o u n d i n g t h e o r e z o n e a t t h e M c L e l l a n M i n e c o n s i s t p r i m a r i l y o f c o m p e t e n t a n d e s i t i c r o c k s a n d t u f f a c e o u s s e d i m e n t s . T h e N o r t h S h e a r i s a m o r e b r o k e n s h e a r e d i n t e r v a l o f s i m i l a r l i t h o l o g y w h i c h i s t h e mos t s i g n i f i c a n t g e o l o g i c a l s t r u c t u r e a f f e c t i n g t h e s t a b i l i t y o f t h e h a n g i n g w a l l o f t h e s t o p e s . T h r e e 217 o t h e r s e t s of o r t h o g o n a l d i s c o n t i n u i t i e s w i l l h a v e l i t t l e e f f e c t o n t h e s t a b i l i t y o f t h e s t o p e w a l l s o r o f t h e s i l l p i l l a r a n d w i l l l i k e l y h a v e o n l y a m i n i m a l e f f e c t o n d i l u t i o n o f o r e b y w a s t e r o c k . H o w e v e r , t h e e f f e c t o f t h e s e d i s c o n t i n u i t i e s o n t h e o v e r a l l c h a r a c t e r of t h e r o c k m a s s m u s t b e c o n s i d e r e d . 9.3 H Y D R O G E O L O G Y T h e h y d r o g e o l o g i c a l s t u d y i n d i c a t e s t h a t w a t e r i n f l o w s w i l l h a v e l i t t l e s i g n i f i c a n c e u p o n t h e m i n i n g o f t h e o r e z o n e . T h e f l o w s i n t o t h e m i n e o p e n i n g s a r e a n t i c i p a t e d to b e l ow a n d u n d e r o n l y m o d e r a t e p r e s s u r e . T h e s e c o n d i t i o n s w i l l h a v e o n l y a m i n o r i m p a c t o n t h e o v e r a l l c h a r a c t e r o f t h e r o c k m a s s . H o w e v e r , d u r i n g t h e h y d r o g e o l o g i c a l s t u d y i t w a s f o u n d t h a t a z o n e of h i g h l y w e a t h e r e d , p e r m e a b l e r o c k of v a r i a b l e t h i c k n e s s e x i s t s a t t h e b e d r o c k s u r f a c e . T h e c o n t a c t b e t w e e n t h e w e a t h e r e d r o c k a n d t h e f r e s h r o c k i s h i g h l y i r r e g u l a r , r e s u l t i n g i n t o p o g r a p h i c a l l y l ow a r e a s w h i c h a r e h y d r a u l i c a l l y c o n n e c t e d to t h e K e e w a t i n R i v e r . T h u s , t h e i n t e r s e c t i o n of t h e c o n t a c t b y t h e m i n e w o r k i n g s c o u l d r e s u l t i n l a r g e i n f l o w s of w a t e r a n d m a t e r i a l s . 9.4 R O C K M A S S C H A R A C T E R I Z A T I O N T h e r o c k m a s s b e l o w t h e f r e s h r o c k / w e a t h e r e d r o c k c o n t a c t 218 h a s b e e n c h a r a c t e r i z e d as p r e d o m i n a n t l y of r e l a t i v e l y h a r d , c o m p e t e n t c h l o r i t i z e d a n d e s i t e a n d t u f f a c e o u s s e d i m e n t s . T h e r o c k m a s s r a t i n g of t h e s e r o c k s v a r i e s c o n s i d e r a b l y w i t h e l e v a t i o n f r o m d o m a i n to d o m a i n . It i s c o n c l u d e d t h a t b e t w e e n e l e v a t i o n 1160 m a n d 1400 m : 1) T h e r o c k m a s s r a t i n g of t h e H a n g i n g Wal l D o m a i n i s 75% w i t h i n t h e a r e a o f i n f l u e n c e of t h e u n d e r g r o u n d e x c a v a t i o n . 2) W i t h i n t h e N o r t h S h e a r , t h e r o c k m a s s r a t i n g r a n g e s f r o m 45% to 50%. 3) A p p r o x i m a t e l y 50% o f t h e h a n g i n g w a l l s o f t h e s t o p e s w i l l b e w i t h i n o r a d j a c e n t to t h e N o r t h S h e a r . 4 ) T h e r o c k m a s s r a t i n g o f t h e F o o t w a l l D o m a i n i s g e n e r a l l y i n t h e o r d e r o f 70% to 75% w i t h i n t h e a r e a o f i n f l u e n c e of t h e u n d e r g r o u n d e x c a v a t i o n s . I s o l a t e d a r e a s of l i m i t e d e x t e n t h a v e r o c k m a s s r a t i n g s i n t h e o r d e r o f 60%. 5) F o r d e s i g n p u r p o s e s t h e m a t e r i a l c o n s t a n t s of t h e r o c k m a s s a r e e s t i m a t e d to b e m = 1 0 , s = 0 . 0 5 b e l o w e l e v a t i o n 1400 m a n d m = 7 . 5 , s = 0 .1 a b o v e e l e v a t i o n 1400 m . 6 ) In t h e N o r t h S h e a r t h e r e s p e c t i v e v a l u e s a r e e s t i m a t e d a t 0 . 5 0 a n d 0 . 0 0 0 1 . H o w e v e r , d u e to t h e l i m i t e d t h i c k n e s s of t h e N o r t h S h e a r i t i s no t e x p e c t e d to h a v e a s i g n i f i c a n t b e a r i n g o n t h e o v e r a l l p i l l a r d e s i g n . 7 ) T h e i n - s i t u d e f o r m a t i o n m o d u l u s o f t h e r o c k s i s e s t i m a t e d a t 50 G P a b e l o w 1400 m a n d 10 G P a b e l o w 1400 m . 219 8) T h e r e s u l t s of t h e l a b o r a t o r y t e s t i n g p r o g r a m w i l l p r o v i d e a d e q u a t e d a t a f o r n u m e r i c a l m o d e l l i n g p u r p o s e s . T h e d e s i g n v a l u e s to b e u s e d a r e s u m m a r i z e d i n T a b l e 9 . 1 . T a b l e 9 .1 D e s i g n V a l u e s f o r N u m e r i c a l M o d e l l i n g D o m a i n L i t h U c s E P C S . G . U n i t ( M P a ) ( G P a ) ( D e g ) ( M P a ) H a n g i n g Wal l A l l 95 50 0 . 2 0 2 . 9 8 N o r t h S h e a r A l l 50 10 0 .17 - - 3 . 0 2 F o o t w a l l T S 92 50 0 .29 - - 2 . 9 0 F o o t w a l l C A 100 50 0 . 1 7 55 11 3 . 0 3 9 . 5 I N - S I T U S T R E S S C O N D I T I O N S T h e v i r g i n s t r e s s c o n d i t i o n s a t t h e m i n e s i t e h a v e b e e n e s t i m a t e d f r o m d a t a o b t a i n e d u s i n g C S I R O h o l l o w i n c l u s i o n s t r a i n g a u g e s . T h e r e s u l t s of t h i s s t u d y i n d i c a t e t h a t : 220 1) T h e m a j o r p r i n c i p a l s t r e s s i s n e a r l y p e r p e n d i c u l a r to t h e o r e b o d y at a n a z i m u t h o f 3 3 6 ° r e l a t i v e to m i n e n o r t h a n d a p l u n g e of 6 ° to t h e s o u t h e a s t . 2) T h e 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 i s n e a r l y p a r a l l e l to t h e o r e b o d y at a n a z i m u t h o f 6 8 ° r e l a t i v e to m i n e n o r t h a n d a p l u n g e of 6 ° to t h e s o u t h w e s t . 3 ) T h e m i n o r p r i n c i p a l s t r e s s a c t s n e a r l y d o w n t h e d i p o f t h e o r e b o d y a t a n a z i m u t h o f 2 1 ° r e l a t i v e to m i n e n o r t h a n d a p l u n g e o f 84o to t h e n o r t h w e s t . In a d d i t i o n , t h e m a g n i t u d e o f t h e p r i n c i p a l s t r e s s e s b e t w e e n t h e 240 m L e v e l a n d 370 m L e v e l a r e e s t i m a t e d to b e : o | = 2 0 . 4 9 M p a 0"2 = 1 .13 o v CTj = 0 . 9 6 O V w h e r e O V = 0 . 0 2 9 M P a / m 9 . 6 E N G I N E E R I N G P R O P E R T I E S O F B A C K F I L L T h e d e t a i l e d l i t e r a t u r e r e v i e w a n d a s s e s s m e n t of t h e g l a c i o - f l u v i a l m a t e r i a l to b e u s e d f o r b a c k f i l l a t t h e M c L e l l a n M i n e i n d i c a t e s t h a t i t w i l l b e s u i t a b l e to p r o v i d e a s u b - a n g u l a r 221 t o s u b - r o u n d e d s i l t y s a n d f i l l w i t h : c o e f f i c i e n t o f u n i f o r m i t y C u = 4 to 6 g r a i n s i z e d i s t r i b u t i o n , D^g . 0 1 5 mm to . 0 5 mm v o i d r a t i o , e 0 . 3 5 to 0 . 7 5 p o r o s i t y n 0 . 2 6 to 0 . 4 3 p e r c o l a t i o n r a t e k 5 c m / h r to 10 c m / h r It i s a l s o e s t i m a t e d t h a t w i t h a v o i d r a t i o i n t h e r a n g e of 0 . 3 5 to 0 . 7 5 , t h e b a c k f i l l w i l l h a v e a n i n - p l a c e d e n s i t y i n t h e r a n g e of 1600 k g / m 3 to 2200 k g / m 3 a n d a n a n g l e of i n t e r n a l f r i c t i o n i n t h e r a n g e of 3 5 ° to 4 5 ° . W h e n t h i s m a t e r i a l i s c o n s i d e r e d w i t h t h e e f f e c t o f n e g a t i v e p o r e p r e s s u r e a n d t h e d i a m e t e r o f t h e c o n t a c t a r e a b e t w e e n t h e t i r e s of t h e m u c k i n g e q u i p m e n t a n d t h e b a c k f i l l , t h e b e a r i n g c a p a c i t y o f t h e f i l l a p p e a r s to b e s u f f i c i e n t f o r a l l c r i t i c a l e v e n t s i n t h e m i n i n g c y c l e e x c e p t t h e c l e a n - u p of t h e f l o o r of t h e c u t . T o c o m p l e t e t h i s w o r k i t w i l l l i k e l y b e n e c e s s a r y to u s e t i r e p r e s s u r e s of 345 k P a o r l o w e r i n t h e b a c k t i r e s . F o r t h e p u r p o s e of i n i t i a l d e s i g n a n d s e n s i t i v i t y a n a l y s i s t h e i n p u t p a r a m e t e r s f o r n u m e r i c a l m o d e l l i n g s h o u l d b e w i t h i n t h e r a n g e s g i v e n i n T a b l e 9 . 2 . 222 T A B L E 9 . 2 R a n g e of D e s i g n P a r a m e t e r s P a r a m e t e r M i n i m u m V a l u e M a x i m u m V a l u e E ( M P a ) 6 . 9 690 \) 0 . 1 5 0 . 4 5 1600 2200 It i s a n t i c i p a t e d t h a t t h e a c t u a l i n - p l a c e v a l u e s w i l l p r o b a b l y b e i n t h e o r d e r of 50 M p a f o r Y o u n g ' s M o d u l u s , 0 . 2 0 to 0 . 3 0 f o r P o i s s o n ' s R a t i o a n d 1800 k g / m 3 t o 2000 k g / m 3 f o r t h e d e n s i t y . 9 . 7 N U M E R I C A L M O D E L L I N G T h e d e t a i l e d n u m e r i c a l a n a l y s e s o f t h e c o n d i t i o n s a t t h e M c L e l l a n M i n e i n d i c a t e t h a t : 1) T h e b a c k f i l l i n a c u t - a n d - f i l l m i n e d o e s p r o v i d e s i g n i f i c a n t s u p p o r t to t h e s t o p e w a l l s . 2 ) T h e s u p p o r t p r o v i d e d b y t h e b a c k f i l l o n l y s l i g h t l y i m p r o v e s t h e s t r e s s c o n d i t i o n s i n t h e s i l l p i l l a r . 3 ) W i t h i n t h e a c c e p t e d r a n g e of m a t e r i a l p r o p e r t i e s of t h e b a c k f i l l , t h e e f f e c t of v a r y i n g t h e s e p r o p e r t i e s i s no t s i g n i f i c a n t . 223 4 ) T h e u s e of a l i n e a r e l a s t i c b a c k f i l l m a t e r i a l w i t h c o n s t a n t s t i f f n e s s c h a r a c t e r i s t i c s i s a d e q u a t e f o r t h e f i n i t e e l e m e n t m o d e l l i n g of t h e M c L e l l a n M i n e . 5 ) T h e r e m e d i a l m e a s u r e s m o d e l l e d w i t h t h e f i n i t e e l e m e n t m o d e l a p p e a r to s i g n i f i c a n t l y i m p r o v e t h e s t r e s s c o n d i t i o n s w i t h t h e s i l l p i l l a r . 6 ) T h e d e s i g n o f a m i n i m u m w i d t h s i l l p i l l a r b e t w e e n t h e t w o s t o p e s may s t e r i l i z e s i g n i f i c a n t o r e r e s e r v e s b o t h a b o v e a n d b e l o w t h e s e s t o p e s . 9 . 8 M I N E D E S I G N B a s e d u p o n t h e c h a r a c t e r i z a t i o n of t h e r o c k m a s s a n d a n a l y s e s c o m p l e t e d u s i n g t h e N G I A n a l y s i s a n d t h e G o l d e r M e t h o d , i t i s a p p a r e n t t h a t l i t t l e to n o r o c k r e i n f o r c e m e n t w i l l b e r e q u i r e d to s u p p o r t t h e w a l l s o f e a c h c u t i n t h e s t o p e f o r t h e d u r a t i o n of t h e c u t c y c l e . T h e f o o t w a l l o f t h e s t o p e w i l l l i k e l y no t r e q u i r e a n y r e i n f o r c e m e n t d u r i n g t h e l i f e o f t h e m i n e . T h e h a n g i n g w a l l w i l l l i k e l y r e q u i r e s u p p o r t o n l y w h e r e i t i s a f f e c t e d b y t h e N o r t h S h e a r . W h e r e v e r t h e N o r t h S h e a r f o r m s t h e H a n g i n g Wal l o f t h e s t o p e o r i s w i t h i n 3 m o f t h e s t o p e , i t i s r e c o m m e n d e d t h a t 2 . 5 m e t r e l o n g S p l i t S e t s b e i n s t a l l e d i n t h e H a n g i n g Wal l a t a 1.0 m e t r e s p a c i n g . T h e s u p p o r t p r e s s u r e p r o v i d e d b y t h e b a c k f i l l s h o u l d b e a d e q u a t e to p r o v i d e l o n g t e r m s t a b i l i t y o f t h e s t o p e w a l l s . 224 W h e r e t h e r o o f o f t h e c u t i s n o t a f f e c t e d b y t h e N o r t h S h e a r a n d t h e s p a n i s 10 m e t r e s o r l e s s , p a t t e r n b o l t i n g w i l l l i k e l y n o t b e r e q u i r e d . W h e r e t h e s p a n i s g r e a t e r t h a n 10 m e t r e s o r t h e r o o f o f t h e c u t i s a f f e c t e d b y t h e N o r t h S h e a r , 2 . 5 m e t r e l o n g S p l i t S e t s s h o u l d b e i n s t a l l e d o n a 1 .0 m e t r e s p a c i n g . T h e r e s u l t s of t h 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 t h a t t h e roo f o f e a c h c u t w i l l b e m a r g i n a l l y s t a b l e i f r e i n f o r c e d as s u g g e s t e d a b o v e . H o w e v e r , w h e n t h e d i s t a n c e f r o m t h e r o o f of t h e l o w e r s t o p e to t h e d r a i n a g e t u n n e l i s l e s s t h a n 30 m e t r e s , t h e m a x i m u m ma jo r p r i n c i p a l s t r e s s i s m o r e t h a n h a l f t h e i n t a c t r o c k s t r e n g t h . F o r t h i s c o n d i t i o n i t i s t h e r e f o r e r e c o m m e n d e d t h a t w e l d e d w i r e m e s h b e i n s t a l l e d w i t h 2 . 5 m e t r e l o n g S p l i t S e t s a t a s p a c i n g of 1 .0 m e t r e . I f c o n t r o l l e d b l a s t i n g t e c h n i q u e s a r e u s e d , d i l u t i o n of t h e m i n e d o r e b y t h e w a s t e r o c k f r o m t h e s t o p e w a l l s i s a n t i c i p a t e d to b e l e s s t h a n 5% w h e r e t h e w a l l s a r e no t a f f e c t e d b y t h e N o r t h S h e a r . W h e r e t h e w a l l s a r e a f f e c t e d b y t h e N o r t h S h e a r , d i l u t i o n m a y b e as h i g h as 10%. T h e m i n i m u m p i l l a r w i d t h , d e f i n e d as t h e m i n i m u m s e p a r a t i o n o f t h e s t o p e s , a p p e a r s to b e i n t h e o r d e r o f 11 m e t r e s to m a i n t a i n a s t r e n g t h : s t r e s s r a t i o of 1 .5 a n d 8 . 5 m e t r e s to m a i n t a i n a s t r e n g t h : s t r e s s r a t i o of 1 . 0 . If r e m e d i a l m e a s u r e s s u c h as r e i n f o r c i n g t h e d r a i n a g e t u n n e l i n t h e s i l l p i l l a r , 225 g r o u t i n g t h e l o w e r 16 m e t r e s of f i l l i n t h e u p p e r s t o p e a n d / o r u s i n g c e m e n t e d f i l l i n t h e u p p e r 16 m e t r e s o f t h e l o w e r s t o p e a r e u n d e r t a k e n , t h e m i n i m u m s a f e p i l l a r w i d t h c o u l d l i k e l y b e r e d u c e d . H o w e v e r , t h e l o a d - c a r r y i n g c a p a c i t y of t h e c o n s o l i d a t e d f i l l i s q u e s t i o n a b l e a n d t h e s e c o n d i t i o n s t h e r e f o r e c a n n o t b e a n a l y z e d a c c u r a t e l y w i t h t h e c u r r e n t s t a t e of t h e a r t . I t i s a n t i c i p a t e d t h a t t h e m a x i m u m d e c r e a s e i n t h e p i l l a r w i d t h w i t h r e m e d i a l m e a s u r e s w o u l d b e i n t h e o r d e r of 2 . 0 m e t r e s to 2 . 5 m e t r e s . It i s t h e r e f o r e c o n s i d e r e d u n l i k e l y t h a t t h e i n c r e a s e d r e v e n u e f r o m a d d i t i o n a l o r e r e c o v e r y w o u l d e x c e e d t h e c o s t o f t h e s e r e m e d i a l m e a s u r e s . I t i s t h e r e f o r e c o n c l u d e d t h a t t h e m i n i m u m s a f e p i l l a r w i d t h i s 1 1 . 0 m e t r e s . H o w e v e r , i f a r o c k m e c h a n i c s d a t a a c q u i s i t i o n p r o g r a m i s i m p l e m e n t e d e a r l y i n t h e m i n e l i f e , t h e a d d i t i o n a l d a t a w i l l e n a b l e a m o r e a c c u r a t e e s t i m a t e o f t h e r e s p o n s e of t h e f i l l a n d t h e p i l l a r to t h e m i n i n g . T h i s w o u l d l i k e l y a l l ow a d e s i g n f o r a s t r e n g t h : s t r e s s r a t i o o f 1 .0 a n d e f f e c t i v e l y r e d u c e t h e m i n i m u m s a f e p i l l a r w i d t h . E x t r a p o l a t i o n o f t h e d a t a to a s t r e n g t h : s t r e s s r a t i o of 1.0 i n d i c a t e s t h a t a s i l l p i l l a r i n t h e o r d e r of 6 m e t r e s to 9 m e t r e s w i d e may m a i n t a i n s a f e w o r k i n g c o n d i t i o n s i n t h e l o w e r s t o p e . 226 B I B L I O G R A P H Y 227 B I B L I O G R A P H Y 1 . A i t c h i s o n , G . D . , K u r z e m e , M . , W i l l o u g h b y , D . R . , G e o m e c h a n i c s C o n s i d e r a t i o n s i n O p t i m i z i n g t h e U s e of M i n e F i l l , P a r t B : T h e I n v e s t i g a t i o n of t h e R e s p o n s e of F i l l as a S t r u c t u r a l C o m p o n e n t , J u b i l e e S y m p o s i u m o n M i n e F i l l i n g , A u s t r . I . M . M . , p p . 3 5 - 4 8 , 1 9 7 3 . 2 . A s k e w , J . , M c C a r t h y , P . L . , F i t z g e r a l d , D . J . B a c k f i l l R e s e a r c h f o r P i l l a r E x t r a c t i o n a t Z C / N B H C , M i n i n g w i t h B a c k f i l l , 1 2 t h C a n a d i a n R o c k M e c h a n i c s S y m p o s i u m , C I M S p e c i a l V o l u m e 1 9 , p p . 1 0 0 - 1 1 0 , 1 9 7 8 . 3 . A u g s t e n , B . E . K . , " O r e M i n e r a l o g y of t h e A g a s s i z S t r a t i f o r m G o l d D e p o s i t " , C a r l e t o n U n i v e r s i t y , B . S c . T h e s i s , 1 9 8 5 . 4 . B a r t o n , N . , R e c e n t E x p e r i e n c e s w i t h t h e Q - S y s t e m of T u n n e l S u p p o r t D e s i g n , P r o c . S y m p o s i u m o n E x p l o r a t i o n f o r R o c k E n g i n e e r i n g , J o h a n n e s b u r g , V o l u m e I, 1 9 7 6 , p p . 1 0 7 - 1 1 7 . 5 . B l a c k w o o d , R . L . , D i a g n o s t i c S t r e s s - R e l i e f C u r v e s i n S t r e s s M e a s u r e m e n t b y O v e r c o r i n g , I n t e r n a t i o n a l J o u r n a l o f R o c k M e c h a n i c M i n e r a l S c i e n c e & G e o m e c h a n i c A b s t r a c t , V o l . 1 5 , p p . 2 0 5 - 2 0 9 , 1 9 7 8 . 6 . B o r g e s s o n , L e n n a r t , M e c h a n i c a l P r o p e r t i e s of H y d r a u l i c B a c k f i l l , P r o c . o f t h e C o n f e r e n c e o n A p p l i c a t i o n o f R o c k M e c h a n i c s to C u t a n d F i l l M i n i n g , I M M , p p . 1 9 3 - 1 9 5 , 1 9 8 1 . 7 . B r o w n , E . T . a n d H o e k , E . , T r e n d s i n R e l a t i o n s h i p s B e t w e e n M e a s u r e d I n - S i t u S t r e s s e s a n d D e p t h , I n t e r n a t i o n a l J o u r n a l o f R o c k M e c h a n i c M i n e r a l S c i e n c e & G e o m e c h a n i c A b s t r a c t , V o l . 1 5 , p p . 2 1 1 - 2 1 5 , 1 9 7 8 . 8 . B u r t o n , J . , F r a n k , C u t - a n d - F i l l S t o p i n g at E l d o r a d o , B e a v e r l o d g e , M i n i n g i n C a n a d a , 6 t h C o m m o n w e a l t h M i n i n g a n d M e t a l l u r g i c a l C o n g r e s s . 9 . C A N M E T R e p o r t , M i n i n g R e s e a r c h L a b o r a t o r i e s , R e p o r t M R P / M R L , 7 9 - 6 6 ( T R ) . 1 0 . C h a n , S a m u e l , S . , P r o b l e m s of P r e d i c t i o n of G r o u n d S t a b i l i t y i n C u t a n d F i l l O p e r a t i o n i n D e e p M i n e s w i t h F i n i t e - E l e m e n t M e t h o d , P r o c . of t h e C o n f e r e n c e on A p p l i c a t i o n of R o c k M e c h a n i c s to C u t a n d F i l l M i n i n g , I M M , p p . 2 9 3 - 2 9 9 , 1 9 8 1 . 1 1 . C o r p , E . L . , R o c k M e c h a n i c s R e s e a r c h i n t h e C o e u r D ' A l e n e M i n i n g D i s t r i c t , P r o c . o f t h e C o n f e r e n c e o n A p p l i c a t i o n of R o c k M e c h a n i c s to C u t a n d F i l l M i n i n g , I M M , p p . 4 0 - 4 8 , 1 9 8 1 . 228 1 2 . C r a y s t o n , L . H . , V a n L o o n , A . F . , H e a t h e r , E . G . , S a n d ' F i l l i n g at M a d s e n R e d L a k e , M i n i n g i n C a n a d a , 6 t h C o m m o n w e a l t h M i n i n g a n d M e t a l l u r g i c a l C o n g r e s s , p p . 2 5 0 - 2 7 1 , 1 9 5 7 . 1 3 . C S I R O I n - S i t u S t r e s s M e a s u r e m e n t F i e l d M a n u a l , R o c k I n s t r u m e n t s P t y , L t d . A u s t r a l i a . 1 4 . D i c k o u t , M . H . , t h e R o l e a n d B e h a v i o u r of F i l l i n M i n i n g , J u b i l e e S y m p o s i u m o n M i n e F i l l i n g , A u s t r . , I M M , p p . 1 - 1 1 , A u g u s t , 1 9 7 3 . 1 5 . D u p o n t , B l a s t e r ' s H a n d b o o k , E . I . d u P o n t d e N e m o u r s & C o . ( I n c . ) , 1977 1 6 . F a m a , M . E . D . , a n d P e n d e r , M . J . , A n a l y s i s of t h e H o l l o w I n c l u s i o n T e c h n i q u e f o r M e a s u r i n g I n - S i t u R o c k S t r e s s , I n t e r n a t i o n a l J o u r n a l o f R o c k M e c h a n i c M i n e r a l S c i e n c e & G e o m e c h a n i c A b s t r a c t , V o l . 1 7 , p p . 1 3 7 - 1 4 6 , 1 9 8 0 . 1 7 . F o r d , R . A . , A R e v i e w o f B a c k f i l l M i n i n g P r a c t i s e s a n d T e c h n o l o g y a t t h e F o x M i n e , M i n i n g w i t h B a c k f i l l , 1 2 t h C a n a d i a n R o c k M e c h a n i c s S y m p o s i u m , C I M S p e c i a l V o l u m e 1 9 , p p . 1 - 5 , M a y , 1 9 7 8 . 1 8 . F r e e z e , R . A . , C h e r r y , J . A . , G r o u n d w a t e r P r e n t i c e - H a l l , I n c . , E n g l e w o o d C l i f f s , N e w J e r s e y , 1 9 7 9 . 1 9 . G o l d e r A s s o c i a t e s , P r e d i c t i o n of S t a b l e E x c a v a t i o n S p a n s f o r M i n i n g a t D e p t h s B e l o w 1000 M e t r e s i n H a r d R o c k , C A N M E T , D S S F i l e N o . 1 7 S Q . 2 3 4 4 0 - 0 - 9 0 2 0 , A p r i l , 1 9 8 1 . 2 0 . H a l l , R . J . , C l a r k e , A . R . , S a n d F i l l i n g a t t h e F r o o d M i n e o f t h e I n t e r n a t i o n a l N i c k e l C o m p a n y of C a n a d a , L i m i t e d , M i n i n g i n C a n a d a , 6 t h C o m m o n w e a l t h M i n i n g a n d M e t a l l u r g i c a l C o n g r e s s , 1 9 5 7 . 2 1 . H e r g e t , G . , R e g i o n a l S t r e s s e s i n t h e C a n a d i a n S h i e l d , 1 3 t h C a n a d i a n R o c k M e c h a n i c s S y m p o s i u m , T o r o n t o , 1 9 8 0 . 2 2 . H e r g e t , G . , D e K o r o m p a y , V . , I n - S i t u D r a i n a g e P r o p e r t i e s o f H y d r a u l i c B a c k f i l l , C I M S p e c i a l V o l u m e 1 9 , C . I . M . M . . p p . 1 1 7 - 1 2 3 , M a y , 1 9 7 8 . 2 3 . H i l l , J o h n R . M . , M c D o n a l d , M i c h a e l , M . , M c N a y , L e w i s , M . , S u p p o r t P e r f o r m a n c e of H y d r a u l i c B a c k f i l l A P r e l i m i n a r y A n a l y s i s , R e p o r t o f I n v e s t i g a t i o n s 7 8 5 0 , U . S . 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K e r e n , L i u , K a i n i a n , S u n , I n f l u e n c e o f T a i l i n g s P a r t i c l e s o n P h y s i c a l a n d M e c h a n i c a l P r o p e r t i e s of F i l l , M i n i n g w i t h B a c k f i l l , P r o c . o f t h e I n t e r n a t i o n a l S y m p o s i u m o n M i n i n g w i t h B a c k f i l l , L u l e a , A . A . B a l k e m a , R o t t e r d a m , p p . 2 1 - 2 9 , 1 9 8 3 . 2 9 . L y o n , G . C . , S l a u g h t e r , P . J . , K e r r , M . H . , T h e D e s i g n a n d O p e r a t i o n of t h e C e m e n t e d H y d r a u l i c F i l l S t a t i o n , M o u n t I S A M i n e s L i m i t e d , J u b i l e e S y m p o s i u m on M i n e F i l l i n g , A u s t r . , I M M , p p . 1 9 1 - 1 9 7 , 1 9 7 3 . 3 0 . M c N a y , L e w i s M . , C o r s o n , D . R . , H y d r a u l i c S a n d f i l l i n D e e p M e t a l M i n e s , R e p o r t o f I n v e s t i g a t i o n 8 6 6 3 , U . S . B u r e a u o f M i n e s , 1 9 7 5 . 3 1 . 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I n - S i t u S t r e s s M e a s u r e m e n t s i n H a l i t e i n C h e s h i r e , P o t a s h i n N o r t h Y o r k s h i r e a n d S l a t e a t D i n o r w i c - P a r t I I , R o c k E n g i n e e r i n g , U n i v e r s i t y of N e w c a s t l e - U p o n - T y n e , A p r i l , 1 9 7 9 . 3 6 . M o r u z i , G . A . , C o n s o l i d a t e d F i l l P r a c t i s e at S t r a t h c o n a M i n e , M i n i n g w i t h B a c k f i l l , 1 2 t h C a n a d i a n R o c k M e c h a n i c s S y m p o s i u m , C I M S p e c i a l V o l u m e 1 9 , p p . 1 0 - 1 5 , 1 9 7 8 . .230 3 7 . N a n t e l , J . H . , A R e v i e w of t h e B a c k f i l l P r a c t i s e s i n t h e M i n e s of t h e N o r a n d a G r o u p , M i n i n g w i t h B a c k f i l l , P r o c . of t h e I n t e r n a t i o n a l S y m p o s i u m of M i n i n g w i t h B a c k f i l l , L u l e a , A . A . , B a l k e m a , R o t t e r d a m , p . 1 7 3 , 1 9 8 3 . 3 8 . N i c h o l s o n , D . 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P a r i s e a u , W i l l i a m , G . , F i n i t e - E l e m e n t M e t h o d A p p l i e d to C u t a n d F i l l M i n i n g , P r o c . of t h e C o n f e r e n c e on A p p l i c a t i o n of R o c k M e c h a n i c s to C u t a n d F i l l M i n i n g , I M M , p p . 2 8 4 - 2 9 2 , 1 9 8 1 . 4 5 . P a r i s e a u , W . G . , M c D o n a l d , M . M . , H i l l , J . R . M . , S u p p o r t P e r f o r m a n c e f o r H y d r a u l i c F i l l s , J u b i l e e S y m p o s i u m on M i n e F i l l i n g , A u s t r . , I M M , p p . 2 1 3 - 2 1 7 , 1 9 7 3 . 4 6 . P a r i s e a u , W i l l i a m G . , e t a l . , A S u p p o r t - P e r f o r m a n c e P r e d i c t i o n M e t h o d f o r H y d r a u l i c B a c k f i l l , R e p o r t of I n v e s t i g a t i o n s 8 1 6 1 , U . S . B u r e a u of M i n e s , 1 9 7 0 . 4 7 . P a t c h e t , S . 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E . , S u b s u r f a c e Conta inment od Rad ioac t i ve Waste - A S t u d y of the S u r f a c e and S u b s u r f a c e S t r u c t u r a l and Groundwa te r Cond i t i ons at Se lec ted U n d e r g r o u n d Mines and E x c a v a t i o n s , E n g i n e e r i n g and Env i ronmen ta l Geology S e c t i o n , T e r r a i n Sc iences D i v i s i o n , Geo log ica l S u r v e y of C a n a d a , Atomic E n e r g y of C a n a d a L imi ted Resea rch C o m p a n y , In te rna l Repo r t N o . 1/177, F e b r u a r y , 1977. 5 3 . R i c c a r d e l l a , P . C . , A n Implementat ion of the B o u n d a r y I n teg ra l T e c h n i q u e fo r P l ana r Prob lems in E las t i c i t y and E l a s t o - p l a s t i c i t y , C a r n e g i e - M e l l o n U n i v e r s i t y , P h D . , Repo r t S M - 7 3 - 1 0 . 54 . R i c h a r d s , B . 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W e n d i a n g , H u a n g , R e n z h o n g , M e i , U s a g e of D o w n w a r d T a i l i n g s - F i l l i n t h e O r e N o . 5 of X i a n g - I I M i n e , M i n i n g w i t h B a c k f i l l , P r o c . o f t h e I n t e r n a t i o n a l S y m p o s i u m o n M i n i n g w i t h B a c k f i l l , L u l e a , A . A . B a l k e m a , R o t t e r d a m , p p . 1 4 1 - 1 5 0 , 1 9 8 3 . 6 9 . W o o d r u f f , S e t h , D . , M e t h o d s of W o r k i n g C o a l a n d M e t a l M i n e s , v o l . 2 , P e r g a m o n P r e s s , 1 9 6 6 . 7 0 . W o r o t n i c k i , G . , W a l t o n , R . , T r i a x i a l " H o l l o w I n c l u s i o n " G a u g e s f o r D e t e r m i n a t i o n of R o c k S t r e s s e s I n - S i t u , T h e I n s t i t u t e of E n g i n e e r s , A u s t r a l i a , N a t i o n a l C o n f e r e n c e P u b l i c a t i o n , N o . 7 6 1 4 , p p . 1 - 8 , 1 9 7 6 . 7 1 . Y u , Y . S . , T o e w s , N . A . a n d W o n g , A . S . , M i n t a b U s e r ' s G u i d e - A M i n i n g S i m u l a t o r f o r D e t e r m i n i n g t h e E l a s t i c R e s p o n s e of S t r a t a S u r r o u n d i n g T a b u l a r M i n i n g E x c a v a t i o n s , M i n e r a l s R e s e a r c h L a b o r a t o r i e s , C A N M E T , D i v i s i o n R e p o r t M R P / M R L 8 3 - 2 5 ( T R ) , M a r c h 1 9 8 3 . 7 2 . Z i e n k o w i c z , O . C . , t h e . F i n i t e E l e m e n t M e t h o d , T h i r d E d i t i o n , M c G r a w - H i l l B o o k C o m p a n y ( U . K . ) L i m i t e d , 1 9 8 2 . A P P E N D I X I S U R F A C E D R I L L H O L E W A T E R L E V E L S 235 APPENDIX I S u r f a c e D r i l l H o l e W a t e r L e v e l s D R I L L H O L E H O L E D E P T H N o . T O W A T E R C O M M E N T S 593 2 3 . 0 596 - D r y to 10 f e e t . B l o c k e d . 597 - T w o h o l e s b o t h p l u g g e d at s u r f a c e . 6 5 - 1 8 7 . 5 6 5 - 1 9 1 2 . 5 O p e n to 30 f e e t . 6 5 - 2 0 0 . 0 S w a m p y g r o u n d . O p e n to 20 f e e t . 6 5 - 2 8 3 . 0 6 5 - 3 0 1 0 . 0 6 5 - 4 8 1 0 . 0 6 5 - 5 5 2 . 5 6 5 - 5 6 5 . 0 O p e n to 520 f e e t . 6 5 - 6 1 1 8 . 5 8 0 - 1 1 8 5 . 0 O p e n to 30 f e e t . 8 0 - 1 5 2 1.5 8 0 - 1 5 3 0 . 5 8 0 - 1 5 4 0 . 5 O p e n to 380 f e e t . 8 0 - 1 5 5 1.5 O p e n to 364 f e e t . 8 0 - 4 3 1 7 . 5 8 0 - 4 6 1 2 . 5 H o l e p l u g g e d at 1 3 . 0 f e e t . 8 0 - 4 8 E 6 5 . 0 8 0 - 4 8 F 656 A i r f l o w i n g u p h o l e f r o m u n d e r g r o u n d w o r k i n g s . 8 0 - 4 9 1 2 . 5 8 0 - 5 3 2 . 5 H o l e p l u g g e d at 3 . 5 f e e t . 8 0 - 5 4 8 . 5 8 0 - 5 5 1 2 . 5 O p e n to 25 f e e t . 8 3 - 1 6 0 . 0 H o l e m a k i n g 3 -4 g p m . 8 3 - 1 7 6 . 0 8 3 - 1 8 2 . 5 8 3 - 1 9 3 . 0 8 3 - 2 2 3 . 0 8 3 - 3 2 1 1 . 0 O p e n to 30 f e e t . 8 3 - 2 3 3 . 5 8 3 - 2 4 4 . 5 B l o c k e d at 5 . 5 f e e t . 8 3 - 2 6 1.5 8 3 - 2 9 2 . 5 8 3 - 3 0 3 . 5 8 3 - 3 1 6 . 0 8 3 - 6 1.8 O p e n to 30 f e e t . 84 -1 4 . 0 8 4 - 1 0 3 . 0 O p e n to 30 f e e t . 8 4 - 1 3 1 1 . 0 O p e n to 30 f e e t . 8 3 - 1 4 5 . 5 8 4 - 1 8 1 1 . 5 O p e n to 30 f e e t . A P P E N D I X II S U M M A R Y OF U N D E R G R O U N D H Y D R O G E O L O G I C M A P P I N G 237 A P P E N D I X II Gene ra l Seepage into U n d e r g r o u n d Open ings N o . of A v e r a g e Open ing D r i l l Est imated Holes F l o w / H o l e * To ta l To ta l Est imated Est imated Tota l F low f rom Flow f rom Est imated D r i l l Holes Gene ra l Seepage* Flow Sha f t - - 5.5 5.5 L e v e l 2 65 0.11 7.3 . 2.2 9.5 L e v e l 3 59 0.02 1.3 1.1 2.4 L e v e l 800 34 0.02 0.9 1.1 2 D r i l lwa te r - - 4 .8 - 4 .8 S u p p l y T O T A L - - 14 .0gpm lO .Ogpm 25 .0gpm To ta l water pumped f rom mine = 35,000 g a l l o n s / d a y = 25 .0gpm * On s i te the est imates were made in l i t r es p e r m inu te . T h e s e va lues have been c o n v e r t e d to ga l lons p e r minute and the total est imates rounded to the neares t g a l l o n . 238 A P P E N D I X II Measurement of Water F lows f rom Holes wi th P a c k e r s D r i l l T ime(sec) Flow Hole to F i l l a in C O M M E N T S N o . 22 1 Pa i l l /min 73-1 - - Connec ted to d r i l l water supp l y 73-2 84 16.4 73-3 - - A s 73-1 73-94 - - A s 73-1 73-96 180 7.7 73-11 - 0.5 E s t i m a t e d , too small to measure 73-90 - 0.5 A s 73-11 73-21 170 8.3 73-23 - - No gate va lve stem 73-86 120 11.5 73-37 70 19.2 73-45 100 13.4 73-80 - 0.3 E s t i m a t e d , too small measure 73-18 - 2 No f low f rom va lve Es t imated f low f rom d r i l l c o l l a r . 72-1 114 12.1 73-9 - 1 E s t i m a t e d , too small to measure . 73-10 - - No gate va lve s tem. 73-5 50 27.7 73-6 - 2 E s t i m a t e d , too small to measure . 73-7 - - No gate va lve s tem. 73-46 d r i p p i n g 0.1 Es t imated 73-47 - 1 No f low f rom v a l v e . Es t imated f low f rom c a s i n g . 73-48 210 6.6 73-49 250 5.5 73-81 70 19.2 73-82 40 34.2 C S N G 4IN P ipe t h r o u g h conc re te b u l k h e a d . No f l ow . 4 " cas i ng - - P i pe t h r o u g h conc re te b u l k h e a d . No f l ow . To ta l Es t imated Flow Es t imated d i t ch f low at shaf t wit Es t imated d i t ch f low at shaf t wit Es t imated d i t ch f low due to f low 190 1pm = 40 gpm h p a c k e r s open 50 gpm h p a c k e r s c losed 10 gpm from p a c k e r s 40 gpm A P P E N D I X III R A N G E OF V A L U E S OF H Y D R A U L I C C O N D U C T I V I T Y A N D P E R M E A B I L I T Y A f t e r F reeze and C h e r r y 1 8 A P P E N D I X III 240 Table 2.2 Range of Values of Hydraulic Conductivity and Permeability Rocks Unconsolidated deposits c — o a «S «S t a) I <n o c •» * s S o I n o 5? Q.-0 <- CZ DOO o i £ a . « :DD c o to c o a> T J < - » C o •oo J C o ti 3"= O ru CP I £ UO i t 51 k k K K K (darcy) (cm2) (cm/s) (m/s) (gal/day/ft 2) r t O 3 rtO" 3 r l O 2 r l - i o 4 -IO"4 -10 -10-r l O 6 - I0 3 -IO' 5 -1 - i o - 2 -10 s - IO 2 - IO' 6 -IO"' - 1 0 - 3 -10 4 -10 -IO' 7 -IO" 2 -IO" 4 -10 3 -1 - IO' 8 - IO' 3 -IO" 3 -10 2 -IO"' - i o - * -IO"4 -IO"6 -10 -10 ' 2 -io-° -IO" 5 -IO' 7 -1 -10" 3 -10"" -IO" 6 : i o - 8 -10-- t o - 4 - IO" 2 -IO" 7 -IO" 9 - I0- 2 -I0" s -IO"1 3 -IO" 8 -io-° - IO' 3 -IO" 6 - IO" 4 - IO ' 9 -IO"" - IO' 4 -IO" 7 - io— 5 -io-° - i o - 2 -IO"5 -IO" 8 - i o - 6 -IO"" - i o - 3 -IO" 6 I 10' Table 2.3 Conversion Factors for Permeability and Hydraulic Conductivity Units Permeability, k* Hydraulic conductivity, K cm* ft* darcy m/s ft/» U.S. gal/day/rt* cm2 1 1.08 x IO-' 1.01 x 10» 9.80 x 10* 3.22 x 10' 1.85 x 10» ft* 9.29 x 10* 1 9.42 X 10>« 9.11 x 10' 2.99 x 10« 1.71 X 10»* darcy 9.87 X 10-» 1.06 X 10->« 1 9.66 X 10"« 3.17 x 10-' 1.82 X 10» m/s 1.02 x 10-1 1.10 X 10~« 1.04 X 10' 1 3.28 2.12 X 10« ft/s 3.11 x 10-« 3.35 x 10"T 3.15 X 10* 3.05 x I0"« 1 6.46 x 10' VS. gal/day/ft'5.42 x IO""* 5.83 x 10-«» 5.49 x JO - 1 4.72 x 10"T 1.55 x 10"« 1 . •To obtain k in ft*, multiply k in cm1 by 1.08 x 10"'. 241 A P P E N D I X IV C S I R G E O M E C H A N ICS C L A S S I F I C A T I O N FOR J O I N T E D R O C K 242 CSIR GEOMECHANICS CLASSIFICATION OF JOINTED ROCK MASSES A. CLASSIFICATION PARAMETERS AND THEIR RATINGS PARAMETER RANGES OF VALUES i Strength of intact rock materiol Point load strength index > 8 MPa 4-8 MFb 2-4 MPa 1-2 MPa For this low range -uniaxial compres-sive test is preferred Uniaxial compressive strength > 200 MPa 100 - 200 MPa 50 -100 MPo 25 - 50 MPo 10-25 MPa 3-10 MPa 1-3 MPa Rating 15 T2 7 4 2 1 0 2 Dril core quality ROD 90%-100% 75% -90% 50%-75% 25%- 50% < 25% Rating 20 17 13 . e 3 3 Spacing of joints >3m l-3m 0.3-lm 50- 300 mm < 50 mm Rating 30 25 20 10 5 4' Conditon of joints Very rough surfaces Not continuous No separation Hard joint wal rock Slightly rough surfcces Separation < 1 mm Hard joint wal rock Slightly rough surfaces Separation < 1 mm Soft joint wal rock Slickensided surfaces or Gouge (5mm thick or Joints open l-5mm Continuous joints Soft gouge>5mm thick or Joints open > 5mm Continuous joints Rating 25 20 12 6 0 5 Ground water Inflow per IOm tunnel length None <25 litres/min 25-125 litres/min > 125 litres/min. jOinf woler p ,-n pr««Sur« major principal stress OR 0 OR 00 - 02 f"Vr UK 0.2-0 5 OR-> 0 5 General conditons un Completely dry UK Moist only (interstitial water) OR Water under moderate pressure OR Severe water problems Rating 10 7 4 0 B. RATING ADJUSTMENT FOR JOINT ORIENTATIONS Strike and dip orientations of joints Very favourable Favourable Fair Unfavourable Very unfavourable Ratings Tunnels 0 -2 -5 -10 -12 Foundations 0 -2 -7 -15 - 25 Slopes 0 -5 -25 -50 -60 C. ROCK MASS CLASSES DETERMINED FROM TOTAL RATINGS Rating 100—81 80—61 60—41 40—21 < 20 Class No 1 II III IV V Description Very good rock Good rock Fair rock Poor rockv Very poor rock D. MEANING OF ROCK MASS CLASSES Class No. 1 II III IV V Averoge stand-up time 10 years for 5m span 6 months for 4 m soon 1 week for 3 m span 5hours for 1.5m span 10min. for 0.5m spon Cohesion of the rock mass >300kPo 20O-3O0kPa 150-200 kPa 100 - 150 kPa < 100 kPa Friction angle of the rock moss >45° 40°-45° 35°-40° 30" -35" <30° TABLE 6 - THE EFFECT OF JOINT STRIKE AND DIP ORIENTATIONS IN TUNNELLING Strike perpendicular to tunnel axis Strike paralel to tunnel axis Dip 0°-20° irrespective of strike Drive with dip Drive agoinst dip Dip 45"-go- Dip 20°-45° Dip 45°-90° Dip 20°-45° Dip 45°-90* Dip 20° -45° Very favourable Favourable Fair Unfavourable Very unfavourable Fair Unfavourable 243 A P P E N D I X V C O M P U T E R C O D E S F O R D I A M O N D D R I L L C O R E L O G S MINERAL TYPE LITHOLOGICAL UNIT INTENSITY DESCRIPTORS JOINT FREQUENCY Quartz = Q ANDESITE A NONE = N BRKS/3 m CLASS Plagioclase P VARIABLE ANDESITE VA WEAK = W Orthoclase = OC AMPHIBOLITIZED ANDESITE AA MODERATE = M 0 - 1 0 Chlorite = CH CHLORITIZED, AMPHIB. AND. CA STRONG = S 2 - 3 1 Biotite = BI TUFFACEOUS SEDIMENTS TS EXCESSIVE = E 4 - 6 2 Sericite = SR CHLOR/CHLOR. AMPHIB. SEDS. CS 7 - 10 3 Talc = TC DACITE/RHYODACITE TUFF DT 11 - 20 4 Hornblende = H CHERT CT GENERAL TEXTURE DESCRIPTORS 21 - 40 5 Carbonate = CA QUARTZ VEIN QV SCHISTOSE = S 41 - 6 0 6 Epidote = EP QUARTZ CARBONATE VEIN QC MASSIVE = M 61 - 70 7 Cordierite = CD SEMI-MASSIVE SULPHIDE SM GNESSIC = G 71 - 80 8 Andalusite = AD LOST CORE LC 81+ 9 Staurolite = ST Garnet GT SPECIFIC TEXTURE DESCRIPTORS Tremolite = TR MINE UNIT (DOMAIN) BRECCIA = X ROCK QUALITY DESIGNATION Actinolite = AC HANGING WALL HW PORPHYR0BLASTIC = B 90 - 100% 5 Anhydrite = AN FOOT WALL FW CLASTIC = C 75 - 90% 4 Apatite = AP NORTH SHEAR NS PORPHYRITIC = P 50 - 75% 3 Gypsum = GY 25 - 50% 2 Magnetite = MG 0 - 2 5 % 1 Galena = GA MINERAL DESCRIPTIONS SECONDARY STRUCTURE Pyrite = PY FINE = F INTENSITY BRKS/3 m CLASS Pyrrhotite = PO MEDIUM = M WEAK 0 - 3 B ORIENTATION Chalcopyrite = CPY1 COARSE = C MODERATE A - 10 .C ACTUAL ANGLE Sphalerite = SPH GRANULAR = ' G HIGH 11 - 40 D TO CORE AXIS Arsenopyrite = ASP BLEBBY = B INTENSE 41+ E Graphite = GPH VEINS = V Linonite = LIM Serpentine = SRP A P P E N D I X VI S A M P L E D I A M O N D D R I L L C O R E L O G F O R P A R T OF H O L E AU84-46 I _ l I a or T O at in UJ z 2: o o or o o or r 01 > Or >-Z 1—or 1 —00 1 _)-) < * 1 3 x 1 o •Z I W Z — I OH-0- aa 1 a-—o 1 1 _ i 1 Oic 1 VU-CO 1 A oor 1 1 oro 1 UJU. CTLUZ I 1- 11 I u DU1Q I or r - I i 1 ul—.O I 1 a vo.a 1 * <_) I — W I UJU. a—uj 3 U 0 . I l-UJJ- I Klh I UJ(/\ I- O I I z I -U vOO I I -12 11—1 I in «ld U".r-0- I «_l>- I —t<3T •— I u * Z — I O—Z I C I O I or I VUJ I 0 0 I I 0 0 I X a in X o 0* I o 1 t* 1 1 1 O I I a 1 1 <* I inu 1 — a. 1 I v >- 1 1 1- 1 1 1 tfo i I o >P"iUJ 0 1 a 1 Olf>- 1 _>•—>- 1 «* or U-icf-Q I Zo —-Oaj 1 1 a 1 1 o >- 1 1 n h 1 1 1 1 a 1 1 •* I OUJ I •£•! 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O x a 0 x a c in a 0 if. a O 0 <_) 0 >-<t a o ino in.o o • ino in 0 0 0 0 in>o 0 0 • 0 0 •J vO o a. —1 0 1 0 0 O _ II e» 0 -—- (VI « — > 0 1  0 e O 0 0 — 0 a > 0 0 a 0 .—• 6 O » » O « 0 0 • 0 • 0 0 • 0 • 0 « 0 a 0 O 0 6 O 0 0 z 0 .—i 0 > 0 0 « » 0 0 • T 0 • 0 O » O 0 a. Jl « 0 CO ~» in •—1 in • in -J 11 CO 11 » 11 > II 0 •—1 t— t— 0 1- 0 1- 0 CD in or in « in in UJ UJ UJ e UJ UJ _) X X •— 0 •— < 1— <r 0 0 » 0 0 •—' a o <—I a o « a o 0 a o 0 X <r X <t 0 < _ i < _ i II coo II a o 11 a o 1  coo 11 in _ J in _ i in _ i in _ l in r— 1— r— t— r— Z 151- 2 XI- 2 XI- 2 01- Z UJ Z UJ z UJ 2 UJ z id 1 t—< X X X 3 I O r O 3 O X 0 X 0 i/.a 0 x a O x a 0 x a O 0 0 O (_) U » » 0 « 000c oooo O K H < O I K U O .xuinu x a x o X —< <3 10 <o xarro xaa;o n u r x a o x x a o x X jr X co>xu_ cr>xu. > i L k >xu.u. >xu.u rr.>xu. cc>u.u. m>u.u. «I <t »—• *T < Q I- <UHCf uuam ooino o<oin <ui- or «io>-ar < <i o—« < < —o o*toin o<»r>in u u i a i u o x x oumo o x < o a oro aoT) ao-o a x a o CO 0 0 in -j «0 0 0 n« CO 0 • • • 4 • • 0 » • * • 0 0 » C II CC II 0 1  0 >- *o >- in>-«<f • <1 • < oin oin mm in in in «t < I in ao (VJ O Jl oin —ro I in>-X o (VJ rvjD —co I rvj < cr 11 r- v-• <r oin —in x O r-rlN -co r-I (VI O II (VI >-in • a CC o O II r->-• < rli/l —in —11 inj-coin —in 247 A P P E N D I X VII P A R T I A L S U M M A R I Z E D 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 F O R H O L E AU84-46 248 ROCK MASS RATING SUMMARY Project: McLellan Mine Date: January, 1985 Hole NO. Au8446 Size BQ Azimuth 181.2° Dip -60.0° Latitude 225.77 m Departure 29.24 m Elev. 1281.82 From To Domain Lith RMR Pt RQD CON SPAC WA 0.68 3.50 HW CA 60 15 8 20 10 7 3.50 8.40 HW TS 71 15 17 12 20 7 8.40 12.20 HW VA 71 15 17 12 20 7 12.20 25.84 HW A 71 15 17 12 20 7 25.84 27.80 HW A 79 15 20 12 25 7 27.80 29.26 HW A 74 15 20 12 20 7 29.26 30.18 HW A 79 15 20 12 25 7 30.18 38.77 HW A 64 15 20 12 10 7 38.77 48.85 HW VA 59 15 15 12 10 7 48.85 50.17 HW VA 71 15 17 12 20 "7 50.17 51.20 HW TS 57 15 13 12 10 7 51.20 52.74 HW TS 74 15 20 12 20 7 52.74 56.58 HW VA 67 15 13 12 20 7 56.58 57.01 HW TS 76 12 17 20 20 7 57.01 69.66 HW VA 59 15 15 12 10 7 69.66 71.89 HW VA 74 15 20 12 20 7 71.89 72.77 HW TS 74 15 20 12 20 7 72.77 81.20 HW VA 64 15 20 12 10 7 81.20 85.20 HW VA 61 15 17 12 10 7 85.20 90.96 HW A 71 15 17 12 20 7 90.96 102.51 HW VA 64 15 20 12 10 7 102.51 105.57 HW VA 74 15 20 12 20 7 105.57 107.03 HW VA 82 15 20 20 20 7 107.03 110.00 HW VA 67 15 13 12 20 7 110.00 112.92 HW VA 69 15 15 12 20 7 112.92 115.98 HW VA 59 15 15 12 10 7 115.98 118.65 HW VA 63 15 15 6 20 7 118.65 120.36 HW AA 74 15 20 12 20 7 120.36 122.52 HW VA 71 15 17 12 20 7 122.52 136.59 HW TS 61 15 17 12 10 7 136.59 138.24 HW VA 74 15 20 12 20 7 138.24 141.68 HW CA 71 15 17 12 20 7 141.68 142.89 HW CA 61 15 17 12 10 7 142.89 144.31 HW CA 74 15 20 12 20 7 144.31 154.90 HW CA 61 15 17 12 10 7 154.90 157.88 HW CA 51 15 13 6 10 7 157.88 162.43 HW CA 74 15 20 12 20 7 162.43 166.87 HW CA 61 15 17 12 10 7 166.87 168.32 HW CA 74 15 20 12 20 7 168.32 169.76 HW CA 55 15 17 6 10 7 169.76 171.27 HW CA 74 15 20 12 20 7 171.27 172.67 HW CA 55 15 17 6 10 7 172.67 177.54 HW CA 71 15 17 12 20 7 177.54 179.17 HW TS 82 15 20 20 20 7 179.17 180.94 HW CA 51 15 13 6 10 7 180.94 184.15 HW TS 71 15 17 12 20 7 A P P E N D I X VIII P A R T I A L C O M P U T E R P R I N T O U T F O R T U F F A C E O U S S E D I M E N T S IN T H E F O O T W A L L 250 OD LHGT I LflT I LONG I ELE V RU841. RQ 9. 05 79. 96 -90.40 1 183. 58 RU841 RQ c • 87 73. 92 -90.29 1 176. 12 RU842 RQ 1 . 02 66. 27 -94. 14 1299. 48 RU842 RQ 7. 24 61 . 73 -94.41 1300. 47 RU843 RQ . 32. 83. 55 -91.91 1283. 17 RU843 RQ 2. 43 63. 47 -92.38 1283. 25 RU843 RQ 4 . 74 61 . 04 -92.45 1283. 25 RU843 RQ . 93 52. 31 -92.72 1283. 28 RU843 RQ 1 . 53 50. 32 -92.78 1283. 29 RU843 RQ 2. 08 38. 55 -93.23 1283. 31 RU843 RQ 2. 52 30. 58 -93.58 1 283. 32 RU843 RQ 7. 84 25. 62 -93.83 1 283. 32 RU843 RQ 1 . 78 13.81 -94.50 1 283. 32 RU843 RQ 1. 27 -1 . 03 -95.45 1 283. 35 RU843 RQ 2. 19 -8. 96 -96.01 1283. 38 RU843 RQ 3. 49 -14 . 53 -96.41 1283. 4 1 RU843 RQ 5. 32 -19 '.60 -96.77 1283. 43 RU844 RQ 6. 04 66. 63 -91.49 1254. 73 RU844 RQ 2. 29 58. 59 -91 .49 1251 . 67 RU844 RQ 3. 15 56. 44 -9 1.49 1250. 89 RU845 RQ 2. 91 68. 85 -91.71 1231 . 59 RU845 RQ 2. 05 65. 22 -91 .63 1229. 17 RU845 RQ 4. 64 62. 31 -91.56 1227. 24 RU847 RQ 2. 60 46. 63 -30.66 1315. 35 RU847 RQ 4. 69 44. 18 -30.75 1316. 20 RU847 RQ 2. 26 16. 68 -31.87 1325. 43 RU848 RQ . 58 65. 98 -27.74 1282. 81 RU848 RQ 6. 33 50. 22 -27.48 1282. 66 RU848 RQ 8. 78 22. 44 -26.93 1282. 23 RU848 RQ 1 . 69 12. 65 -26.64 1281 . 98 RU848 RQ 1. 72 -1 . 75 -26.04 1281 . 51 RU848 RQ 6. 51 -18 .84 -25.25 1280. 84 RU848 RQ 2. 13 -25.33 -24.96 1280. 59 RU849 RQ .53 67. 75 -29.15 1257. 37 RU849 RQ 1 . 37 49. 49 -29.22 1250. 24 RU849 RQ 1. 03 29. 83 -29.28 1243. 39 RU849 RQ 4. 28 28. 86 -29.29 1243. 05 RU849 RQ 4. 25 24. 82 -29.30 124 1 . 64 RU849 RQ 2. 84 20. 80 -29.32 1240. 25 RU849 RQ 8. 66 -10 . 48 -29.43 1229. 73 RU8410 RQ 3. 39 55. 01 -26.86 1228. 38 RU8410 RQ 2. 96 34. 17 -26.28 1217. 20 RU8410 RQ 1. 43 25. 45 -26.04 1212. 52 RU8411 RQ 1 . 97 38. 21 -30.06 1343. 01 RU8412 RQ 4. 37 55. 36 -19.36 1 195. 38 RU8412 RQ 1 . 89 36. 58 -14.93 1 179. 29 RU8412 RQ 5. 85 35. 13 -14.55 1 178. 14 RU8412 RQ 4. 40 30. 63 -13.34 1 174. 59 RU8413 RQ 2. 04 57. 94 -1.58 1320. 66 RU8413 RQ 2. 53 56. 06 -1 . 63 1321 . 44 RU8413 RQ 1 1 . 97 53. 37 -1 . 70 1322. 51 RU8413" RQ 1 . 92 36. 22 -2. 15 1328. 58 RU8413 RQ 1 . 22 32. 84 -2. 24 1329. 78 RU8413 RQ 5. 46 21 . 79 -2. 53 1333. 72 RU8414 RQ 7. 89 59. 70 -1.08 1301 . 66 FLAT FLOMG FELEV D0MF;T LGR PHF 74. 26 -90.29 1176.55 Fli TS JP 71 72. 1 1 -90.25 1173.39 FU TS JP 74 65. 27 -94.20 1299.76 FU TS GlE 10 54. 66 -94.84 1301.97 FU TS OE 7 6 83. 23 -91.91 1283.13 FU TS QE SO 61 . 04 -92.45 1283.25 Fli TS GlE 6 1 56. 31 -92.59 1283.27 FN TS QE 79 51 . 38 -92.74 1283.28 FN TS QE 71 48. 79 -92.83 1283.29 Fli TS QE 77 36. 47 -93.32 1283.31 FN TS GlE 73 28.06 -93.71 1283.32 FN TS QE 7 3 17. 79 -94.27 1283.32 FN TS QE 73 12.03 -94.61 1283.32 FN T3 QE 70 -2.30 -95.54 1283.35 FN TS QE 73 -11.14 -96. 17 1283.39 FN TS QE 73 -17.93 -96.65 1283.42 FN TS GlE t > -24.91 -97.15 1283.46 FN TS GlE 71 61 . 00 -91 .49 1252.55 FN TS JP 71 56. 44 -91 .49 1250.89 FN TS JP 71 53. 48 -91.49 1249.81 FN TS JP 71 66. 43 -91.66 1229.97 FN TS JP 61 63. 51 -91.59 1228.04 FN TS JP 74 58.44 -91.47 1224.70 FN TS JP 64 44.18. -30.75 1316.20 FN TS JP 53 39. 75 -30.92 1317.73 Fli TS JP 79 14.53 -31.96 1326.14 FN TS JP 87 65.40 -27.73 1282.81 FN TS JP 10 43. 89 -27.36 1282.57 FN TS JP 81 13. 67 -26.68 1282.02 FN TS JP 79 10. 96 -26.58 1281.93 FN TS JP 79 -3.46 -25.96 12ei.44 FW TS JP 81 -25.33 -24.96 1280.59 FN TS JP 92 -27.46 -24.86 1280.51 FN TS JP 9i' 67. 25 -29. 15 1257.18 FN TS JF 51 48. 20 -29.22 1249.79 FN TS JP 81 28. 86 -29.29 1243.05 FN TS JP 65 24. 82 -29.30 1241.64 FN TS JP 74 20. 80 -29.32 1240.25 FN TS JP 52 18.12 -29.33 1239.31 FN TS JP 74 -18.14 -29.45 1227.24 FN TS JP 64 52. 02 -26.78 1226.78 FN TS JP rf. f. 31.56 -26.21 1215.80 FN TS JF 74 24. 19 -26.00 1211.85 FN TS JP 74 36. 54 -30.08 1344.06 FN TS JP 79 52. 15 -18.65 1 192.50 FN TS JP 74 35. 13 -14.55 1178.14 FN TS JP 74 30.63 -13.34 1174.59 FN TS JP 79 27. 25- -12.42 1171. 93_FII- TS JP 68 56. 06 -1 . 63 1321 .44 FN TS JP 68 53. 72 -1 . 70 1322.38 FN TS IP 79 42.09 -2. 00 1326.50 FN TS JP 34. 41 -2. 20 1329.22 FN TS JP 79 31 . 69 -2. 27 1330.18 FN TS JP 62 16.47 -2. 67 1335.30 FW TS JP 68 52. 00 -1. 23 1303.37 FN TS JP 97 A P P E N D I X IX S U M M A R Y OF D E T A I L E D I N V E S T I G A T I O N OF T H E N O R T H S H E A R 252 DRILL N .S . INTERSECT TRUE ASSAY RESULTS COMMENTS HOLE From To THICK From To Oz/Ton AU84- 1 111. 00 112. 80 3. 1 111.00 112.00 0 Ore zone w i t h i n 3 m AU84-•2 73. 17 75. 96 1. 58 73.17 75.96 <.040 Ore zone w i t h i n 3 m AU84- 3 70. 64 72. 63 2 . 10 70.64 71.07 .001 Ore zone w i t h i n 3 m 71.07 71.65 .120 71.65 72.08 .010 72.08 72.63 .120 AU84-•4 72. ,55 74. 01 11. 67 72.55 74.01 <0.10 No ore zone w i t h i n i „ AU84-•5 81. .42 83 . 19 13. 98 81.42 82.00 .060 _i in Ore zone w i t h i n 3 m 82.00 82.50 .100 82.50 83.19 .070 AU84-•6 89. .04 91 . 08 89.04 91.08 <.060 Ore zone w i t h i n 3 m AU84-•7 67. .07 71. 64 3 . 76 67.07 71.64 <.020 Ore zone w i t h i n 3 m AU84-•8 59. .77 62. 51 2 . 74 59.77 60.52 .030 Ore zone w i t h i n 3 m 60.52 60.92 .461 60.92 61.66 .280 61.66 62.51 .070 AU84--9 59, .70 65. ,55 5. 59 59.70 62.00 £.070 62.00 .62.52 .190 62.52 63.09 .180 63.09 63.50 .060 63.50 64.03 .080 64.03 64.57 .280 64.57 65.55 <.010 Ore zone w i t h i n 3 m AU84--10 69 .59 72, .58 8. ,47 69.59 70.20 .001 70.20 70.50 .150 70.20 i n t o 72.58 70.50 71.00 .080 averages above 71.00 71.52 .130 0.08 o z / t o n 71.52 72.00 .090 72.00 72.58 .070 AU84--11 77 .46 85, .37 6. ,32 77.46 82.00 <.030 Ore zone w i t h i n 3 m 82.00 82.60 .670 82.60 83.30 .940 82.00 - 85.37 83.30 83.85 .080 averages above 83.85 85.37 <.050 0.13 o z / t o n AU84--12 88 .41 94 .00 4, .38 88.41 89.77 7 89.77 90.29 .060 90.29 90.83 .250 90.29 m to 92.50 i m 90.83 91.46 .170 averages above 91.46 92.00 .040 0.13 o z / t o n 92.00 92.50 .250 253 DRILL N .S . INTERSECT TRUE ASSAY RESULTS COMMENTS HOLE From To THICK From To Oz/Ton 92.50 93.10 .120 -93.10 94.00 <.050 Ore zone w i t h i n 3 m AU84- 13 77.95 79.56 1.45 77.95 78.51 .170 Average over 78.51 78.95 .020 0.13 o z / t o n 78.95 79.56 .470 Ore zone w i t h i n 3 m AU84- 14 70.48 71.54 1.01 70.48 71.05 0.04 Ore zone w i t h i n 3 m 71.05 71.54 0.14 AU84- 15 63.62 67.07 3.45 63.62 67.07 <0.02 Ore zone w i t h i n 3 m AU84- 16 70.61 72.27 1.59 69.80 70.61 0.35 Average over 70.61 70.93 0.01 0.13 o z / t o n 70.93 71.61 0.10 Ore zone w i t h i n 3 m 71.61 72.27 0.01 AU84- 17 77.76 79.27 1.29 77.76 78.15 0.03 78.15 78.50 1.424 Averages over 78.50 79.27 .01 0.13 o z / t o n AU84- 18 . 97.03 100.00 1.95 97.03 100.00 <0.02 Ore zone w i t h i n 3 m AU84- 19 89.50 90.34 0.67 89.50 90.34 <0.02 Ore zone w i t h i n 3 m AU84- 20 82.32 84.58 1.76 82.32 84.22 <0.04 Ore zone w i t h i n 3 m 84.22 84.58 0.274 AU84- 21 83.51 85.37 1.59 83.51 85.37 <0.01 Ore zone w i t h i n 3 m AU84- 22 63.04 64.78 1.74 63.04 64.50 <0.06 Ore zone w i t h i n 3 m 64.50 64.78 0.46 AU84- 23 74.15 74.74 0.56 74.15 74.50 0.16 Average over 74.50 74.74 0.06 0.08 o z / t o n AU84-•24 73.03 76.02 2.89 73.03 76.02 <0.02 Ore zone w i t h i n 3 m AU84-•25 68.35 68.59 0.24 68.35 68.59 <0.01 Ore zone w i t h i n 3 m AU84- 26 69.76 70.86 1.08 69.76 70.86 <0.02 Ore zone w i t h i n 3 m AU84-•27 84.16 87.10 3.72 84.16 84.80 0.02 Averages over 84.80 85.37 0.24 0.13 o z / t o n 85.37 86.00 0.05 86.00 86.48 0.04 86.48 87.10 1.468 AU84-•28 104.00 106.51 2.22 104.00 104.50 0.07 _ 104.50 104.95 0.11 104.95 106.00 0.01 Ore zone w i t h i n 3 m 106.00 106.51 0.20 AU84-•29 244.04 256.79 10.46 244.04 255.79 <0.05 No ore zone w i t h i n o _ AU84-•30 85.60 86.73 0.98 85.60 86.73 <0.07 Ore zone w i t h i n 3 m AU84-•31 77.60 78.20 1.04 77.60 78.02 0.38 Ore zone below 254 DRILL N.S . INTERSECT TRUE ASSAY RESULTS COMMENTS HOLE From To THICK From To Oz/Ton 78.02 78.20 ? -AU84- 32 70. 66 72. 15 1.49 70.66 71.63 <0. 06 Ore zone w i t h i n 3 m 71.63 72.15 0. 14 72.15 72.66 0. 10 AU84- 33 73. 82 75. 09 1.21 73.82 75.09 <0. 07 Ore zone w i t h i n 3 m 75.09 75.50 p. 09 AU84- 34 82. 55 83. 51 0.82 82.55 83.51 • 001 Ore zone w i t h i n 3 m AU84- 36 302. 42 315. 57 1.23 302.42 315.57 No ore zone w i t h i n 7 m AU84- 37 55 . 55 63. 22 8.10 55.55 63.22 <0. 10 j m No ore zone w i t h i n 7 m AU84- 38 91 . 46 93 . 67 1.95 91.46 93.67 <0. 01 j m No ore zone w i t h i n 7 m AU84- 39 9 1 . 46 93 . 67 1.95 91.46 93.67 <0. 01 j m No ore zone w i t h i n 7 rr\ AU84- 40 79. 75 80. 65 2.64 79.75 80.65 <0. 08 J IT) No ore zone w i t h i n 7 m AU84- 41 71. 90 74. 70 2.80 71.90 72.46 001 j m No ore zone w i t h i n 72.46 74.20 010 3 m 74.20 74.70 0. 12 AU84- 42 73. 45 74. 60 1.81 73.45 74.00 001 Ore zone below 74.00 76.60 • 130 AU84- 43 81 . 90 84. 08 1.96 81.90 84.08 <. 06 No ore zone w i t h i n AU84- 44 108. 23 109. 76 2.00 108.23 108.73 1. 112 j m Ore Zone 108.73 109.27 0 . 713 109.27 109.76 0. 397 AU84- 46 219. 53 226. 00 5.98 219.53 226.00 <0. 070 No ore zone w i t h i n AU84- 47 85. 37 86. 89 1.23 85.37 86.89 0 . 12 j m No ore zone w i t h i n AU84- 48 69. 13 71 . 04 1.78 69.13 69.62 0. 110 j m No ore zone w i t h i n 69.62 70.12 0. 190 3 m • 70.12 71.04 0. 030 AU84- 49 62. 00 62. 95 0.94 62.00 62.95 <0. 050 M a r g i n a l ore zone below AU84- 50 62. 78 64. 42 1.60 62.78 64.42 <0. 060 Ore zone below AU84- 51 72. 70 73. 66 2.72 72.70 73.66 040 No ore zone w i t h i n AU84-•52 97. 56 98. 48 0.67 97.56 98.48 <. 090 j m No ore zone w i t h i n 3 m 255 DRILL HOLE AU84-53 AU84-54 AU84-55 AU84-56 AU84-57 AU84-58 AU84-59 AU84-60 AU84-61 AU84-62 AU84-63 AU84-64 AU84-65 AU84-66 AU84-67 AU84-68 AU84-69 AU84-70 AU84-71 AU84-72 AU84-73 N . S . INTERSECT TRUE From To ASSAY RESULTS 244.30 258.37 96.98 98.43 82.10 76.22 73.17 86.00 THICK From To Oz/Ton 244.30 258.37 <.01O 1.16 96.98 98.43 <.010 82.10 77.42 1.73 76.22 77.10 3.62 73.17 3.61 85.67 1.14 106.59 108.04 0.73 302.75 303.96 <.040 0.62 71.64 72.30 86.00 <.060 77.42 <.010 77.10 <.010 89.93 0.60 67.50 67.97 2.93 89.72 1.65 87.41 1.89 78.25 0.65 67.26 1.52 62.50 2.71 66.60 2.24 38.80 2.17 28.50 .030 .180 .030 67.97 68.59 92.84 0 89.06 <.001 79.54 <.04 67.91 .010 64.02 <.020 67.25 0.93 74.71 75.80 £.020 1.53 102.84 104.59 <.050 104.59 105.01 .120 74.18 75.50 <.010 41.18 <.030 30.76 <.010 COMMENTS No ore zone w i t h i n 3 m Marg ina l ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m Wi th in ore zone No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m 256 DRILL HOLE AU84-74 AU84-75 AU84-76 AU84-77 AU84-78 AU84-79 AU84-80 AU84-81 AU84-82 AU84-83 AU84-84 AU84-85 AU84-86 AU84-87 AU84-88 AU84-89 N .S . INTERSECT TRUE ASSAY RESULTS From To THICK From To Oz/Ton 3.26 36.70 40. 06 <.060 1.41 32.01 33. 44 <.040 2.00 40.91 4 1 . 54 .130 41.54 42 . 17 .080 42.17 44. 20 <.040 0.95 42.68 43 . 14 .020 43.14 43 . 63 .677 3.54 241.78 252. 13 .001 0.98 312.28 313. 72 0.83 79.01 79. 97 <.070 1.20 69.74 70.25 1.98 64.02 4.33 60.72 1.37 72.21 0.84 94.51 70.25 70.95 .190 .130 66.02 <.030 65.10 <.040 73.76 <.090 97.56 <.020 0.48 101.57 102.13 .001 0.69 87.58 1.32 79.27 2.54 79.74 88.31 <.030 81.59 <.001 82.32 .001 AU84-92 0.46 80.57 81.13 .010 AU84-93 0.80 70.80 71.65 <.070 AU84-94 0.73 63.45 64.18 <.040 AU84-95 1.21 63.37 63.82 .070 63.82 64.23 .741 64.23 64.61 .210 AU84-96 0.87 71.50 72.48 <.020 AU84-97 2.16 97.56 99.66 <.020 99.66 100.19 .060 COMMENTS No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m Ore zone w i t h i n 3 m Ore zone beldw. No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m Ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m Ore zone w i t h i n 3 m Ore zone w i t h i n 3 m Ore zone w i t h i n 3 m Wi th in ore zone. Ore zone below. 257 DRILL N .S . INTERSECT TRUE HOLE From To THICK ASSAY RESULTS From To Oz/Ton COMMENTS. 100.19 100.61 .080 100.61 101.00 .210 AU84-98 2.56 73.17 76.22 £.040 AU84-99 1.47 62.99 64.55 >.130 AU84-100 1.29 63.46 .240 64.75 .190 AU84-101 0.90 64.41 65.33 £.080 AU84-102 2.90 70.97 74.25 £.100 AU84-103 2.76 95.77 98.56 £.060 98.56 99.01 .180 99.01 99.90 .250 AU84-104 1.74 81.80 83.57 £.030 AU84-105 1.32 75.08 76.45 .010 AU84-106 2.90 68.33 69.37 £.030 69.37 69.88 .618 69.88 70.41 .020 70.41 70.84 .610 70.84 71.23 .358 AU84-107 1.80 69.12 70.37 .010 70.37 70.95 .230 AU84-108 2.20 74.60 76.61 £.030 76.61 76.97 1.446 AU84-109 0.76 94.57 95.50 .050 AU84-110 80.29 80.81 .270 80.81 81.46 .030 81.46 82.26 .050 AU84-111 1.71 69.74 72.02 £.100 AU84-112 3.04 62.96 63.52 .040 63.52 64.00 .170 64.00 64.51 .200 64.51 64.99 .130 66.02 66.02 £.030 AU84-113 1.77 65.91 67.71 £.100 AU84-114 1.55 74.01 75.77 £.020 AU84-115 1.98 99.66 102.32 £.010 No ore zone w i t h i n 3 m Wi th in ore zone. Wi th in ore zone. No ore zone w i t h i n 3 m No ore zone "wi th in 3 m Ore zone below. Ore zone w i t h i n 3 m Ore zone below. Wi th in ore zone. Ore zone below. Ore zone below. Ore zone below. Ore zone below. No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m No ore zone w i t h i n 3 m Ore zone w i t h i n 3 m No ore zone w i t h i n 3 m 258 DRILL HOLE AU84-116 AU84-117 AU84-118 AU84-119 AU84-120 AU84-121 AU84-122 N.S . INTERSECT TRUE ASSAY RESULTS From To THICK From To Oz/Ton 2.42 267.60 270.96 COMMENTS No ore zone w i t h i n 3 m 1.72 79.72 80.79 1.32 74.36 1.97 68.14 69.54 1.35 69.57 ? 76.69 ? 107.67 108.23 108.23 108.78 108.78 109.27 80.79 £.020 81.53 .200 Ore zone below. 75.76 <.020 Ore zone below. 69.54 <.070 70.12 .260 Ore zone below. 71.18 <.080 No ore zone w i t h i n 3 m 79.27 <.070 No ore zone w i t h i n 3 m .100 .420 No ore zone w i t h i n .090 3 m. 259 A P P E N D I X X S T R E S S - S T R A I N C U R V E S F O R U N I A X I A L C O M P R E S S I V E T E S T S O B T A I N E D F R O M L V D T R E A D I N G S 260 S5Q 225 200 175 ^ 150 CD 125 cn UJ Or: _ i (E 75 t—< X cr U N I R X I R L COMPRESSIVE TEST SAMPLE #1 . a + .4' r EJ in Pi ca in r-. is ra CD 6> IO ro ra in a in ra co CM IO r.j R X I R L S T R R I N (MICROSTRRIN) IS o © et U N I A X I A L C O M P R E S S I V E TEST SAMPLE #3 + 4' A ' * I I ! E I S 1 K 1 w w OJ eg R X I A L S T R A I N (M ICROSTRAIN) U N I A X I A L C O M P R E S S I V E TEST SAMPLE #4 •*' .4' -j i J? £ "> c o . m c K 5 ^ 5 ~ ~ ~ ~ C M I N J O J O J O J A X I A L S T R A I N (M ICROSTRAIN) 262 RXIRL STRRIN (MICROSTRRIN) A P P E N D I X X I S T R E S S - S T R A I N C U R V E S F O R U N I A X I A L T E S T S F R O M S T R A I N G A U G E S 250 U N I R X I R L C O M P R E S S I V E T E S T RXIBL VS DIAMETRAL STRAIN #2 225 -2QD -173 -150 (MPa) 123 STRESS 100 -DIRMETRRL x~~^* STRESS 73 SD 23 -I ^ X R X I R L 0 ^ i i i i i I I i l l i i a 333 503 750 1003 125D 1503 1758 2000 STRRIN (MICROSTRRIN) 2£5D £500 2?5G 300C U N I R X I R L C O M P R E S S I V E T E S T #4 250 - RXIRL VS DIRMETRRL STRAIN V 225 -2Q0 -173 -150 - DIRMETRRL .x-""* •—\ n Q. 123 CO tee to u a: r - 73 / y^- AXIAL 50 -23 n i i i i i i i i • i i i u a 230 308 753 10011 1250 1503 .1750 2000 2250 2500 2750 300C STRRIN (MICROSTRRIN) 267 A P P E N D I X XII S T R E S S - S T R A I N C U R V E S FOR T R I A X I A L T E S T S ro 0-r tn in or v-m X rr 309 275 250 225 208 175 150 125 iee 75 50 25 TRIflXIRL COMPRESSIVE TEST CONFINING STRESS = 6.99 MPa SRMPLE #2 GJ Ei ra GJ CJ E> GJ GJ GJ GJ 13 ci GJ GJ EJ a CJ GJ GJ E> GJ G> GJ El GJ GJ GJ CD a o CD EJ a CD © o G> GJ © *"" ru n t CD N CD CO CD ru cn AXIAL STRRIN (MICROSTRRIN) ro a. to CT) U Oi r -tn x rr 275 250 225 208 175 150 125 188 75 50 25 TRIRXIflL COMPRESSIVE TEST SAMPLE #3 CONFIHINC STRESS » 6.90 MPa .« ^ G J O E J a GJ GJ GJ GI GJ GJ GJ GJ »3 n n SJ G> cs 2 03 GJ a GJ GJ GJ GJ GJ GJ CO E) a 5 CD CD E> a CD CO CD D a CD G< ru n in CD »> m o> CD *"* ru m T RXIRL STRRIN (MICROSTRRIN) 250 " 260 (fl ^ 175 150 125 180 in UJ CE (-in _i rr X 75 50 25 T R I A X I A L COMPRESSIVE T E S T SAMPLE #4 COHFIMIHC STRESS = 6.90 MPa GJ H <3 ra El ra ra ra ra (3 ra ra EJ (3 ro ra E) o ra ra ra ra ra ra E" a ID SI © ca © © © © a Gi © Rl 01 in CD 01 ro Cl T R X I R L S T R R I N (MICROSTRAIN) in cn 300 275 £50 225 280 175 150 125 160 75 50 25 0 T R I R X I R L COMPRESSIVE T E S T SRMPLE #5 CONFINING STRESS - 17.46 MPa ra ra ra ra ra ra ra El s ra ra ra El a ra o ra S <S ra ra ra ra ra ra ra ra ra ra ra ra G> © ca CD © CD © <3 CD © CD © a © © ru n in (0 Is- CTJ © ci in R X I R L S T R R I N (MICROSTRAIN) 271 390 275 250 225 <- 200 Kl in in _j cr. x CE 150 50 25 TRIRXIRL COMPRESSIVE TEST SRMPLE #6 CONFINING STRESS = 13.79 MPa ra ra GI ra IS ra 03 E l GJ GJ ra ra GI ra SJ c> (S e i EJ @ G> ra ra ra CP 5 5 S CD © © © 8 © © © © ca © © PJ n •d- m CO (D 0 ) © ru •n RXIRL STRRIN (MICROSTRRINJ in in u QC I QZ X cc 275 250 225 200 175 150 125 100 75 50 25 TRIRXIRL COMPRESSIVE TEST SRMPLE #7 CONFINING STRESS = 13.79 MPa 1 1 t 1 1 I 1 1 1 1 1 1 1 , , ra ra E l ra ra ra ra E> ta ra ra ra E l ra n ra ra S ra ra ra ra ra ra ra ra ra E< ra ra ra © © © © © © © a © © © © © © © n j cn (0 ra co © r u n RXIRL STRRIN (MICROSTRRIN) 272 ro r to CD U Qi rx X 350 225 -260 175 150 125 100 75 50 25 a T R I A X I A L COMPRESSIVE T E S T SAMPLE #8 CONFINING STRESS » 13.79 MPa A X I A L S T R A I N (MICROSTRRIN) cn txJ or: rr i — i x rr 275 225 sea 175 150 125 100 75 50 25 0 T R I A X I A L C O M P R E S S I V E T E S T SAMPLE #9 CONFINING STRESS •= 2 0 . 6 9 MPa A X I R L S T R A I N (MICROSTRRIN) ro LT) to UJ or r-tn _i rx i—< X rr 275 250 225 288 175 150 125 188 75 50 25 8 T R I A X I A L COMPRESSIVE T E S T SAMPLE #10 CONFINING STRESS = 20-69 MPa 1 1 1 1 1 1 1 1 t 1 1 1 1 1 1 GJ GJ CJ GJ GJ GJ E) GJ GJ GJ GJ GJ Gl GJ GJ a GJ ?J GJ GJ EJ ra GJ GJ GJ EJ GJ GJ CD D 5 CD CD CD fD a Q CD CD ED a CD CD ru n in CD r- 03 O) CD ru cn rr in A X I R L S T R A I N (MICROSTRRIN) 250 T R I A X I A L C O M P R E S S I V E T E S T SAMPLE #11 CONFINING STRESS •= 20.69 MPa ro CL LO LO or r-LO X rr 225 288 175 150 125 188 75 50 25 8 A X I R L S T R A I N (MICROSTRRIN) A P P E N D I X XII I S P E C I F I C G R A V I T Y T E S T D A T A 275 SAMPLE Wx W2 NO. (gm) (gm) 1 867.7 165.3 2 867.7 121.7 3 867.7 161.1 4 867.7 210.6 5 867.7 70.9 6 867.7 123.9 7 867.7 73.6 8 867.7 128.4 9 867.7 223.3 10 867.7 108.6 11 1017.6 225.3 12 867.7 129.5 13 867.7 126.1 14 867.7 404.5 15 867.7 188.7 16 1017.6 183.5 17 1017.6 325.2 18 867.7 254.4 19 867.7 405.3 (gm) (gm) 974.2 58.8 2.81 947.0 42.4 2.87 971.9 56.9 2.83 1008.7 69.6 3.02 914.6 24.0 2,95 949.9 41.7 2.97 917.4 23.9 3.07 952.8 43.3 2.96 1019.3 71.1 3.11 941.6 34.7 3.13 1169.6 73.3 3.07 952.1 45.1 2.87 951.2 42.6 2.96 1142.6 129.6 3.12 991.9 64.5 2.93 1135.1 66.0 2.78 1238.0 104.8 3.10 1034.0 88.1 2.89 1132.9 140.1 2.89 A P P E N D I X X I V S T R A I N R E L I E F C U R V E S F R O M O V E R C O R I N G NIUaiSOdDIH O V E R C O R E N O . 3 -300 r -208 \--100 r ..X 6-2 100 h z M tx H cn o U M 200 r-300 L 400 r-500 r-600 TIME (Min) 279 in Niuaisoaoiw MICROSTRRIN 08Z A P P E N D I X X V A D J U S T E D S T R A I N R E L I E F C U R V E S F O R O V E R C O R E N O . 2 A N D 3 MICROSTRAIN MICROSTRRIN A P P E N D I X X V I S T R E S S - S T R A I N C U R V E S F R O M B I A X I A L T E S T S 1208 r BIAXIAL TEST OVERCORE NO. 2 800 h . 3 G-7 G-l CE I -o &. u 400 f-0 -400 -808 * + B = " z = ^ G-3 - j ^ ~ ; ^ 4 G - 5 •+ -+ G - 9 G-2 8. 8 •1200 -6 0 6 12 S T R E S S ( M p a ) 18 24 30 236 ro CO u o u U > o I-cn u CE n X GE n PQ Q 01 OJ to 1 I ta ia (9 Q CO G9 Q rt I OJ CO id — D_ u LD H rs C3 (S co (3 OJ co I 1 5 0 0 r 1 0 0 0 h 5 0 0 H BIRXIRL TEST OVERCORE NO. 4 G-l 1 7 CC on o o 0 h - 5 0 0 H - 1 0 0 0 •1500 - G 0 12 18 24 3 0 STRESS (Mpa) 288 in u o <J Ld > o Q in •8 ( 3 in J CD CM — CL in w u LO H i n I ts in to l N I U a i S ° J O l u j A P P E N D I X XV I I M A J O R P R I N C I P A L S T R E S S D I S T R I B U T I O N A R O U N D T H E MINE O P E N I N G S F O R S T A G E 6 T H R O U G H 12 E X C A V A T I O N S WITH NO A D D I T I O N A L S U P P O R T CONTOUR PLOT. MAJOR PRINCIPAL STRESS CONTOUR PLOT. MAJOR PRINCIPAL STRESS FILE MCLELS8 TIME- 0 FILE MCLELG3 TIME- 0 O IMS - *** MCLELLAN MINEt TEST MESH HORIZONTAL DISPS. IMS - *** MCLELLAN MINE: TEST MESH HORIZONTAL DISPS. CONTOUR PLOT. MRJOR PRINCIPAL STRESS FILE MCLEL61B TIME- 0 1 M S - «*» MCLELLAN MINE: TEST MESH HORIZONTAL DISPS. CONTOUR PLOT. MRJOR PRINCIPAL STRESS FILE MCLELE11 TIME- 0 IMS - *** MCLELLAN MINE: TEST MESH HORIZONTAL DISPS. 292 CONTOUR PLOT. MAJOR PRINCIPAL STRESS FILE MCLELG12 TIME- 0 IMS - *** MCLELLAN MINE: TEST MESH HORIZONTAL DISPS. A P P E N D I X XVI I I M A J O R P R I N C I P A L S T R E S S D I S T R I B U T I O N A R O U N D T H E MINE O P E N I N G S F O R S T A G E 12 E X C A V A T I O N S WITH V A R I O U S R E M E D I A L M E A S U R E S CONTOUR PLOT. MRJOR PRINCIPAL STRESS FILE MCLELB12 TIME- 0 IMS - *** MCLELLRN MINE; TEST MESH HORIZONTRL DISPS. CONTOUR PLOT. MRJOR PRINCIPAL STRESS FILE MCLEL712 ' TIME- 0 1 IMS - *** MCLELLRN MINE: TEST MESH HORIZONTRL DISPS. ro CONTOUR PLOT. MRJOR PRINCIPAL STRESS PILE MCLEL812 TIME- 0 IMS - # w » MCLELLRN MINE: TEST MESH HORIZONTRL DISPS CONTOUR PLOT. MRJOR PRINCIPAL STRESS FILE MCLEL912 'TIME- 0 i IMS - * * w MCLELLAN MINE: TEST MESH HORIZONTRL DISPS. tn A P P E N D I X X I X C O N T O U R E D S T R E S S D I S T R I B U T I O N I N T H E S I L L P I L L A R F O R T H E L A S T S T A G E O F E X C A V A T I O N CONTOUR P L O T . M R J O R P R I N C I P R L S T R E S S F I L E M C L E L G 1 Z T I M E - 0 I M S _ »«H M C L E L L B N M I N E : T E S T M E S H H O R I Z O N T A L D I S P S . CONTOUR P L O T . M A J O R P R I N C I P A L S T R E S S F I L E M C L E L 7 1 2 T I M E - 0 I M S - * * * M C L E L L A N M I N E : T E S T M E S H H O R I Z O N T A L D I S P S . A P P E N D I X X X D E T A I L E D S T R E S S C O N D I T I O N S IN T H E S I L L P I L L A R F O R E A C H C O M P U T E R R U N IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL68 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 208 1 101.1 16.9 . 198 -.026 20.8 209 1 96.6 15.2 .184 -.021 162 . 3 214 1 63.8 25.1 .108 . 022 5.9 215 1 65. 0 24. 6 . 109 .021 178.9 226 1 55.2 25. 4 . 091 . 026 .7 227 1 55.3 25.1 .091 . 026 1.0 232 1 50.1 21.9 . 087 . 017 163.1 233 1 84 .9 27.6 . 144 . 019 . 9 234 1 49.7 21.6 . 087 . 017 17. 1 255 1 47.0 29. 9 . 077 . 035 165. 1 257 1 47.1 30.3 .077 . 036 16. 2 262 1 74.2 16. 0 .137 -.005 164.1 263 1 96.4 8.7 .172 -.019 179.6 264 1 74.5 16.1 . 137 -.006 15.9 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL69 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 214 1 99.3 15.7 . 194 -.027 20.2 215 1 99.9 15.2 .189 -.022 163 . 2 226 1 69.3 25.4 . 118 . 020 6.6 227 1 69.7 25.0 .118 . 019 176. 2 232 1 58.0 23.2 .101 . 017 166. 1 233 1 96. 6 29.7 . 165 . 018 1.0 234 1 57.8 22 . 9 . 101 . 016 14.5 255 1 52.2 31.8 . 084 .037 167 . 8 257 1 52.3 32 . 3 . 085 . 037 14.0 262 1 80.5 17.1 . 149 -.006 164.2 263 1 105.5 9.4 . 188 -.021 179.7 264 1 80.5 17.1 . 149 -.007 15.8 301 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL610 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 226 1 105. 6 17.8 .204 -.024 19.4 227 1 104.8 16. 6 . 198 -.021 163 . 3 232 1 71.9 24.6 . 123 . 017 172.9 233 1 116.9 30.4 . 202 .013 1.5 234 1 72.4 23.8 . 125 . 015 8 . 6 255 1 60.1 34 . 1 . 097 . 039 173.7 257 1 60. 6 34.4 . 098 . 039 9 . 3 262 1 88. 6 18 . 2 . 163 -.008 164 . 8 263 1 119.6 10.4 .213 -.025 179.8 264 1 89.2 18.2 . 165 -.008 15. 4 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL611 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 232 1 115.3 20.2 .215 -.018 16. 0 233 1 174.5 6 . 5 .315 -.052 2 . 4 234 1 115.4 18.3 . 212 -.017 167 . 0 255 1 75.4 33.0 . 129 .029 12 . 6 257 1 77.1 32.8 . 130 . 030 172 . 2 262 1 104.6 19.7 . 191 -; 010 166. 3 263 1 150.1 11.7 .268 -.033 . 2 264 1 105.6 19.1 . 194 -.012 13 .7 302 I M S - M C L E L L A N M I N E : T E S T M E S H H O R I Z O N T A L D I S P L A C E M E N T S P R I N C I P A L S T R E S S E S A N D S T R A I N S F I L E : M C L E L 6 1 2 T I M E = 0 E L E M M A T L 1 - S T R E S S 3 - S T R E S S S T R A I N - 1 % S T R A I N - 3 % A N G L E 2 5 5 1 9 6 . 9 6 . 2 . 2 5 5 - . 1 0 5 3 7 . 5 2 5 7 1 9 1 . 6 6 . 3 . 2 4 1 - . 0 9 8 1 4 2 . 5 2 6 2 1 1 4 4 . 4 2 4 . 6 . 2 7 4 - . 0 2 8 1 6 2 . 2 2 6 3 1 2 4 2 . 5 2 3 . 2 . 4 3 2 - . 0 4 6 . 4 2 6 4 1 1 4 7 . 7 2 1 . 6 . 2 8 4 - . 0 3 7 1 8 . 3 I M S - M C L E L L A N M I N E : T E S T M E S H H O R I Z O N T A L D I S P L A C E M E N T S P R I N C I P A L S T R E S S E S A N D S T R A I N S F I L E : M C L E L 7 8 T I M E = 0 E L E M M A T L 1 - S T R E S S 3 - S T R E S S S T R A I N - 1 % S T R A I N - 3 % A N G L E 2 0 8 1 1 0 0 . 8 1 6 . 9 . 1 9 7 - . 0 2 6 2 0 . 8 2 0 9 1 9 6 . 4 1 5 . 1 . 1 8 3 - . 0 2 1 1 6 2 . 3 2 1 4 1 6 3 . 5 2 5 . 1 . 1 0 7 . 0 2 2 5 . 9 2 1 5 1 6 4 . 7 2 4 . 5 . 1 0 8 . 0 2 1 1 7 8 . 9 2 2 6 1 5 4 . 5 2 5 . 4 . 0 8 9 . 0 2 6 r: • 9 2 2 7 1 5 4 . 7 2 5 . 2 . 0 9 0 . 0 2 6 . 8 2 3 2 1 5 0 . 0 2 2 . 8 . 0 8 5 . 0 2 1 1 6 6 . 6 2 3 3 1 7 5 . 2 2 7 . 4 . 1 2 6 . 0 2 2 . 8 2 3 4 1 4 9 . 7 2 2 . 6 . 0 8 4 . 0 2 0 1 3 . 5 2 5 5 1 4 8 . 0 2 7 . 7 . 0 7 9 . 0 3 1 1 6 6 . 4 2 5 6 4 1 5 . 6 7 . 3 . 1 4 1 . 0 4 2 1 7 9 . 8 2 5 7 1 4 8 . 1 2 8 . 0 . 0 7 9 . 0 3 1 1 4 . 5 2 6 2 1 - 7 4 . 4 1 6 . 3 . 1 3 8 - . 0 0 6 1 6 2 . 9 2 6 3 1 8 7 . 9 8 . 5 . 1 5 6 - . 0 1 6 1 7 9 . 6 2 6 4 1 7 4 . 7 1 6 . 5 . 1 3 9 - . 0 0 6 1 7 . 2 303 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL79 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 214 1 98.9 15.7 . 193 -.026 20.3 215 1 99.5 15.1 . 188 -.021 163 . 1 226 1 68.6 25.4 . 116 . 020 6.8 227 1 69. 0 25.0 . 117 . 020 175.9 232 1 58.0 24.2 . 098 . 021 169.6 234 1 57.9 23.9 . 098 . 020 10.9 255 1 53 . 3 29.5 . 087 . 032 - 168.6 256 4 17 .4 7.9 . 158 . 044 . 1 257 1 53.5 29.9 .088 . 032 12.7 262 1 80. 2 17.3 . 149 -.007 163 .1 263 1 96.1 9.1 . 171 -.018 179.7 264 1 80.7 17.4 .150 -.007 17. 0 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL710 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 226 1 104.5 17.8 .201 -.023 19.5 227 1 103 .8 16. 6 . 195 -.020 163 . 2 232 1 72.0 25.5 .122 . 019 176.4 233 1 103 .9 29.9 .178 . 016 1.5 256 4 20.3 8.5 . 186 . 044 .7 257 1 61.9 31.9 . 102 . 034 8.8 262 1 88 . 7 18. 6 .164 -.008 163 . 6 263 1 108.7 10.0 . 194 -.021 179.8 264 1 89.3 18. 6 . 166 -.009 16. 6 304 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL711 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 232 1 115. 6 20.6 .219 -.020 17.7 233 1 154.7 5.6 .279 -.046 2 . 4 256 4 27.7 8.5 .261 . 029 2 . 5 257 1 78.8 30.5 . 133 . 025 173 . 6 262 1 104. 3 20.1 . 192 -.010 165. 2 263 1 135.2 11. 0 .241 -.029 . 1 264 1 105.4 19.7 . 194 -.012 14.9 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL712 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 256 4 57.2 10. 3 .552 -.011 1.0 257 1 109.8 13.1 .238 -.059 152 . 8 262 1 132.7 23.2 .245 -.018 165. 3 263 1 193 .1 15.5 . 345 -.041 . 4 264 1 135.7 21.2 .253 -.025 15.3 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL88 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 208 1 98.1 16.5 .192 -.025 20.8 209 1 93.9 14.7 . 178 -.020 162. 3 214 1 61.1 24.4 . 102 . 021 5.6 215 1 62.3 23 . 8 . 104 . 020 178.9 232 1 46.1 22 . 2 . 078 . 021 166. 0 233 1 67.9 26.3 . 113 . 023 . 3 234 1 45.9 22.0 . 077 . 021 13.5 255 1 43.3 27.9 . 069 . 034 170. 4 256 4 13 . 6 7.2 . 121 . 045 178 . 9 257 1 43.4 28.0 . 069 . 034 8.9 262 1 61.8 18.6 . 108 . 008 168.6 263 1 74 .4 16.2 . 129 . 002 179 . 7 264 1 61.4 18.6 . 107 . 008 11. 2 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL89 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 214 - 1 95.3 15.2 .186 -.025 20.3 215 1 96.0 14 . 6 . 181 -.020 163 . 0 232 1 53.7 23.5 .090 . 021 169.2 233 1 77.7 28.2 . 131 .023 . 4 234 1 53.6 23 . 2 . 090 . 020 10.7 255 1 48.3 29.7 . 077 . 035 172.8 256 4 15.2 7.7 .136 . 047 179.2 257 1 48.4 29.8 . 077 . 036 7.2 262 1 66.8 19.7 .117 . 008 168.7 263 1 81.6 17.3 . 142 . 001 179.8 264 1 66.4 19.6 .116 . 008 11. 2 306 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL810 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 226 1 99.2 17 .2 .191 -.022 19. 6 227 1 98.7 16. 0 . 186 -.019 163 . 0 232 1 66.9 24.7 . 112 . 020 176. 6 233 1 94.6 28.6 . 161 . 017 1.1 234 1 67.4 23.9 .114 .018 4.7 255 1 55. 8 31.6 .090 . 037 178.1 256 4 17.8 8.3 . 161 . 047 . 1 257 1 56.2 31.6 . 091 . 036 3 . 3 262 1 74 . 0 21.0 . 130 .008 169.1 263 1 92 . 6 18.7 . 161 . 000 179.9 264 1 73.7 20.8 .129 . 007 10.9 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL811 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 232 1 107.5 19.8 .204 -.018 18.2 233 1 141. 6 5.3 . 255 -.042 2 . 3 234 1 107.8 18.0 .200 -.017 164.7 255 1 70.4 30.3 .121 . 025 14 . 6 256 4 24.6 8.2 .229 . 033 2.3 257 1 72 .1 29.7 . 123 . 025 168 . 8 262 1 87.3 22.5 . 153 . 006 170.9 263 1 115.9 20.5 .203 -.004 . 2 264 1 87.3 21.9 . 153 . 005 9 . 0 307 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL812 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 255 1 105. 0 13.5 .235 -.062 29.5 256 4 50.1 9.4 .482 -.006 .8 257 1 101.5 12.2 .225 -.059 151.2 262 1 110.9 25.7 . 195 . 003 171. 1 263 1 165.9 26.6 .292 -.011 . 6 264 1 112.2 23.7 . 199 -.001 9.6 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL98 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 208 1 101. 0 16.9 .198 -.026 20.8 209 1 96.6 15.1 .183 -.021 162.3 214 1 63.7 25.1 . 107 . 021 5.9 215 1 65.0 24.5 . 109 . 020 178.8 226 1 55.2 25.4 .091 . 026 ' .7 227 1 55.3 25.1 .091 . 025 1.0 232 1 50. 0 21.8 . 087 . 017 163.0 233 1 84.9 27.6 . 144 . 019 . 8 234 1 49.6 21.6 .086 . 016 17.1 235 1 47.4 22.6 . 079 . 022 8.2 255 1 46.9 29.8 . 076 . 035 165. 0 257 1 47.0 30.2 .077 . 035 16. 1 262 1 74.2 16.0 . 136 -.005 164.1 263 1 96.3 8.7 . 172 -.019 179 . 6 264 1 74.5 16.1 . 137 -.005 15.9 308 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL99 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 214 1 92.4 14 . 6 . 180 -.024 20.0 215 1 93.2 14.1 . 176 -.020 163.3 226 1 62. 6 23 . 3 .105 . 019 5.5 227 1 63 . 0 22.8 . 106 . 018 176. 6 232 1 50.4 21.1 . 087 . 016 165. 0 233 1 80.7 26.6 . 137 . 019 .1 234 1 50.2 20.7 . 087 . 016 14.6 255 1 43.4 29.7 . 068 . 037 170.5 257 1 43 . 5 29.8 .068 . 038 7.4 262 1 57.9 17.8 .100 . 009 170. 3 263 1 79.8 16.2 . 139 . 001 179.4 264 1 57.5 17.7 . 099 . 009 9.1 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL910 TIME = 0 ELEM MATL, 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 226 1 85.4 14.8 .164 -.018 19.4 227 1 85.1 13 . 6 . 160 -.017 163 .1 232 1 57. 8 20.6 . 098 . 015 173 . 1 233 1 92 . 0 24.5 .158 . O i l 1.0 234 1 58.2 19.8 .099 . 013 7.7 255 1 47.4 29 . 5 . 075 . 036 179.8 257 1 47.8 29.5 . 076 . 036 .7 262 1 61. 7 18.1 . 107 . 008 171.2 309 IMS - - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL911 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 232 1 81.3 15.2 .152 -.011 16.7 233 1 123.3 4.0 . 223 -.037 2 . 2 234 1 81. 8 13.6 . 150 -.011 166. 0 255 1 54. 6 25.9 . 095 .021 17.7 257 1 55.9 25.1 . 096 . 021 165. 3 262 1 68.5 18.2 .119 . 006 173 . 3 263 1 101.2 17.4 . 177 -.005 . 1 264 1 68.4 17.4 . 119 .005 6.0 IMS - MCLELLAN MINE: TEST MESH HORIZONTAL DISPLACEMENTS PRINCIPAL STRESSES AND STRAINS FILE: MCLEL912 TIME = 0 ELEM MATL 1-STRESS 3-STRESS STRAIN-1 % STRAIN-3 % ANGLE 255 1 61. 5 4.5 . 163 -.067 38.4 257 1 59.2 4.2 . 157 -.065 141. 5 262 1 83.7 20.5 . 148 .002 169. 1 263 1 141.2 25. 0 . 247 -.005 . 2 264 1 84.5 18.7 . 151 -.001 11.1 A P P E N D I X X X I S I L L P I L L A R S T A B I L I T Y A N A L Y S I S 311 PILLAR STABILITY ANALYSIS RUN MCLEL6 ° S p e c i f i c Conditions: 1) F i l l unconsolidated 2) Drainage tunnel not supported. FILE: MCLEL68 PILLAR WIDTH: 24.5 m ELEMENT NO. MAJOR PRINC. STRESS (C T -L) MPa MINOR PRINC. STRESS (a 2) MPa ELEM STRENGTH (°lcs) MPa STRENGTH: STRESS RATIO 208 101.1 16.9 134.1 1.33 209 96.6 15.2 126.7 1.31 214 63.8 25.1 166. 6 2 . 61 215 65. 0 24.6 164.7 2 . 53 226 55.2 25.4 167.7 3 . 04 227 55.3 25.1 166.6 3 . 01 232 50.1 21.9 154.3 3 . 08 233 84.9 27. 6 175.7 2 . 07 234 49.7 21.6 153.3 3 . 08 255 47.0 29.9 183 .7 3.91 257 47.1 30.3 185.2 3.93 262 74.2 16. 0 130.2 1.75 263 96.4 8.7 95.1 0.99 264 74.5 16.1 130.7 1.75 Average STRENGTH:STRESS RATIO (2) 2.46 Average (3) 68.6 152.5 2 . 22 Average (4) 68.6 21.7 168.4 2.45 312 FILE: MCLEL69 PILLAR WIDTH: 20.5 m ELEMENT MAJOR PRINC. MINOR PRINC. ELEM STRENGTH STRENGTH: NO. STRESS (O T _ ) STRESS (o 2) (°lcs) STRESS MPa MPa MPa RATIO 214 99.3 15. 7 128.9 1.30 215 99.9 15.2 126.7 1.27 226 69.3 25.4 167.7 2.42 227 69.7 25. 0 166.2 2 . 38 232 58. 0 23 . 2 159.4 2 .74 233 96.6 29.7 183.1 1.89 234 57.8 22.9 158.3 2.74 255 52.2 31.8 190. 3 3 . 65 257 52.3 32 . 3 192.0 3 . 67 262 80.5 17.1 135.0 1. 68 263 105.5 9.4 98.8 0.94 264 80.5 17 . 1 135.0 1. 68 Average STRENGTH:STRESS RATIO (2) 2.19 Average (3) 76.8 153.5 2 . 00 Average (4) 76.8 22.1 155.2 2 .02 FILE: MCLEL610 PILLAR WIDTH: 16.5 m ELEMENT MAJOR PRINC. MINOR PRINC. ELEM STRENGTH STRENGTH: NO. STRESS ( O T J STRESS (o 2) (°lcs) STRESS MPa MPa MPa RATIO 226 105. 6 17.8 137.9 1.31 227 104.8 16. 6 132.8 1.27 232 71.9 24 . 6 164.7 2 .29 233 116.9 30.4 185.5 1.59 234 72.4 23.8 161.7 2.23 255 60.1 34.1 198.1 3.30 257 60. 6 34.4 199.1 3.29 262 88 . 6 18.2 139.6 1.58 263 119.6 10.4 104.0 0.87 264 89. 2 18.2 139.6 1. 56 Average STRENGTH:STRESS RATIO (2) 1. 93 Average (3) 89.0 156. 3 1.75 Average (4) 89.0 22 . 9 158.3 1. 78 313 FILE: MCLEL611 PILLAR WIDTH: 12.5 ni ELEMENT MAJOR PRINC. MINOR PRINC. ELEM STRENGTH STRENGTH: NO. STRESS (o a) STRESS ( o 2 j (°lcs) STRESS MPa MPa MPa. RATIO 232 115.3 20.2 147.7 1.28 233 174.4 6.5 82.5 0.47 234 115.4 18.3 140. 0 1.21 255 75.4 33.0 194.4 " 2.57 257 77.1 32.8 193.7 2.51 262 104.6 19.7 145. 7 1.39 263 150.1 11.7 110.5 0.74 264 105. 6 19.1 143 . 3 1.36 Average STRENGTH:STRESS RATIO (2) 1.44 Average (3) 114.7 • 144.7 1.26 Average (4) 114.7 20.2 147.6 1.29 FILE: MCLEL612 PILLAR WIDTH: 8.5 in ELEMENT MAJOR PRINC. MINOR PRINC. ELEM STRENGTH STRENGTH-NO. STRESS (Ox) STRESS (o 2) ( o l c s ) STRESS MPa MPa MPa RATIO 255 96.9 6.2 80.7 0.83 257 91.6 6.3 .81.3 0.89 262 144.4 24.6 164 . 7 1.14 263 242.5 23.2 159 .4 0.66 264 147.7 21.6 153 .3 1.04 Average STRENGTH:STRESS RATIO (2) 0.91 Average (3) 144. 6 ' 127.9 0.88 Average (4) 144.6 16.4 131.9 0.91 

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