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Toppling failure in the Marmot Vertical Limb at Quintette Coal Ltd., Tumbler Ridge, British Columbia Moore, Duncan Michael 1989

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TOPPLING FAILURE IN THE MARMOT VERTICAL LIMB AT QUINTETTE COAL LTD. TUMBLER RIDGE, BRITISH COLUMBIA By DUNCAN MICHAEL MOORE B.A.Sc, The University of B r i t i s h Columbia, 1987 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE THE FACULTY OF GRADUATE STUDIES (Department of Mining and Mineral Process Engineering) We accept t h i s t h e s i s as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA MAY 1989 © Duncan Michael Moore, 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 May 2 5 / 8 9  DE-6 (2/88) A B S T R A C T Two y e a r s i n a row Q u i n t e t t e C o a l L t d . h a d a t o p p l i n g f a i l u r e o c c u r o n t h e N o r t h W a l l i n t h e M a r m o t V e r t i c a l L i m b . T h e w a l l h a s a n o v e r a l l a n g l e o f a p p r o x i m a t e l y 50 d e g r e e s , a n d t h e s t r a t i g r a p h y , c o n s i s t i n g o f p o o r q u a l i t y s a n d s t o n e a n d s h a l e , i s d i p p i n g a l m o s t v e r t i c a l . T h e J u l y 2 7 t h b e n c h s c a l e t o p p l i n g f a i l u r e , was i n i t i a t e d b y h i g h p o r e p r e s s u r e s g e n e r a t e d i n t e n s i o n c r a c k s . T h e S e p t e m b e r 1 8 t h t o p p l i n g f a i l u r e was a m u l t i - b e n c h f a i l u r e , w h i c h h a d b e e n d e v e l o p i n g f o r o v e r a y e a r . A l t h o u g h w a t e r p r e s s u r e s d i d n o t i n i t i a t e f a i l u r e , t r a n s i e n t w a t e r t a b l e s c o n t r i b u t e d t o t h e o v e r a l l i n s t a b i l i t y . B o t h f a i l u r e s w e r e t h e r e s u l t o f p o o r w a l l d e s i g n a n d b l a s t i n g d a m a g e . T h i s t h e s i s p r e s e n t s t h e b a c k g r o u n d m a t e r i a l , t h e m i n e a n d m o n i t o r m e t h o d d e v e l o p e d a n d t h e b a c k a n a l y s i s o f t h e f a i l u r e . T h e a r e a s r e s e a r c h e d i n c l u d e : r e g i o n a l a n d l o c a l g e o l o g y , s t r u c t u r a l g e o l o g y i n t h e V e r t i c a l L i m b , m i n e d e v e l o p m e n t , t h e g r o u n d w a t e r c o n d i t i o n s e n c o u n t e r e d , t h e b l a s t i n g p r a c t i c e s u s e d , t h e a r t i f i c i a l s u p p o r t s y s t e m s i n s t a l l e d a n d t h e m o n i t o r i n g n e t w o r k e s t a b l i s h e d . T h e a n a l y s i s o f t h e f a i l u r e u s e d t h e D i s t i n c t E l e m e n t M e t h o d d e v e l o p e d b y P e t e r C u n d a l l . T h i s m e t h o d i s a r e c o g n i z e d d i s c o n t i n u u m m o d e l l i n g a p p r o a c h , w h i c h i s u s e d t o m o d e l j o i n t e d m e d i a s u b j e c t e d t o q u a s i - s t a t i c o r d y n a m i c l o a d i n g . T h e m e t h o d h a s b e e n c o m p a r e d t o t h e L i m i t E q u i l i b r i u m A n a l y s i s p r o p o s e d b y Goodman a n d B r a y i n 197 6, b u t m o s t o f t h e w o r k i n v o l v i n g UDEC ( U n i v e r s a l D i s t i n c t E l e m e n t Code) h a s c e n t r e d a r o u n d t u n n e l d e s i g n a n d s u p p o r t r e q u i r e m e n t s , r o c k r e i n f o r c e m e n t , f l u i d f l o w t h r o u g h a j o i n t e d m e d i a , d y n a m i c l o a d i n g a n d t h e r m a l - m e c h a n i c a l m o d e l l i n g . I n t h i s t h e s i s t h e r o c k mass i s a n a l y z e d a s a s e r i e s o f r i g i d b l o c k s , w h i c h a r e s u b j e c t e d t o g r a v i t a t i o n a l f o r c e s . T h e p u r p o s e o f UDEC i s n o t t o d e s i g n p i t w a l l s o r b e t t e r d a m s , b u t r a t h e r t o b e u s e d as a t o o l t o b e t t e r u n d e r s t a n d how a j o i n t e d r o c k mass b e h a v e s u n d e r s t a t i c a n d d y n a m i c l o a d s . i i i T A B L E OF CONTENTS A B S T R A C T i i T A B L E OF CONTENTS i v L I S T OF T A B L E S v i i i L I S T OF F I G U R E S i x ACKNOWLEDGEMENT x i i i 1. INTRODUCTION 1 1 . 1 Q U I N T E T T E C O A L L T D 1 1 .2 PURPOSE AND SC OP E OF T H E WORK 2 2 . S I T E CONDITIONS 4 2 . 1 L O C A T I O N AND A C C E S S 4 2 . 2 PHYSIOGRAPHY 4 2 . 3 S U R F A C E HYDROLOGY 6 2 . 4 C L I M A T I C CONDITIONS 7 3 . GEOLOGY 8 3 . 1 GEOLOGIC U N I T S I N T H E V E R T I C A L L I M B 11 3 . 1 . 1 HULCROSS MEMBER 11 3 . 1 . 2 GATES MEMBER 14 3 . 1 . 3 C O A L SEAMS I N T H E MARMOT V E R T I C A L L I M B 17 4 . MINE DEVELOPMENT 18 4 . 1 CURRENT MINE P L A N I N THE V E R T I C A L L I M B . . . 18 4 . 2 MINE DEVELOPMENT UP TO MAY 1988 2 0 4 . 3 PROPOSED DEVELOPMENT FOR THE V E R T I C A L L I M B . 2 6 4 . 4 A C T U A L DEVELOPMENT OF T H E V E R T I C A L L I M B . . . 28 4 . 5 MINE AND MONITOR METHOD 31 5 . S T R U C T U R A L GEOLOGY 32 5 . 1 R E G I O N A L S T R U C T U R A L GEOLOGY 32 5 . 2 S T R U C T U R A L MAPPING PROGRAMS 33 5 . 2 . 1 S T R U C T U R A L DATA AND I T S I N T E R P R E T A T I O N 3 3 5 . 3 S T R U C T U R A L GEOLOGY I N THE V E R T I C A L L I M B . . . 37 5 . 3 . 1 BEDDING AND BEDDING J O I N T S . . . . 38 5 . 3 . 2 J O I N T I N G 38 5 . 3 . 3 F A U L T S 42 5 . 3 . 4 T Y P E OF F A I L U R E S A S S O C I A T E D WITH THE STRUCTURE 42 i v 6. GROUNDWATER HYDROLOGY 46 6.1 PIEZOMETERS 4 6 6.2 INTERPRETATION OF THE NORTH WALL HYDROLOGY . 49 6.3 SURFACE RUNOFF 50 6.4 DEWATERING THE VERTICAL LIMB 51 6.4.1 HORIZONTAL DRAINS 52 6.4.2 DRAINAGE GALLERY 54 6.4.3 DRAINAGE IN THE VERTICAL LIMB . . . 54 6.5 EFFECT OF GROUNDWATER ON WALL STABILITY . . . 56 7. BLASTING 59 7.1 BLASTING AND ITS EFFECT ON WALL STABILITY . . 59 7.2 BLASTING PARAMETERS AND THEIR EFFECT ON PERFORMANCE 60 7.3 INITIAL BLASTING PRACTICES IN THE VERTICAL LIMB 63 7.4 CURRENT BLASTING PRACTICES IN THE VERTICAL LIMB 66 7.5 POSSIBLE IMPROVEMENTS AND RECOMMENDATIONS . . 68 7.5.1 INCLINED SMALL DIAMETER HOLES . . . 69 7.5.2 REDUCTION OF EXPLOSIVE CHARGE . . . 69 7.5.3 DELAYS BETWEEN BUFFER HOLES . . . . 73 2 8. ARTIFICIAL SUPPORT 73 8.1 SUPPORT SYSTEMS USED IN THE VERTICAL LIMB . . 74 8.1.1 SWELLEX BOLTS 75 8.1.2 DYWIDAG 75 8.2 ROCK BOLT PATTERN 79 9. MONITORING 83 9.1 LEVELS OF MONITORING USED IN THE VERTICAL LIMB 83 9.1.1 PRIMARY 83 9.1.2 SECONDARY 85 9.1.3 MINE AND MONITOR 89 9.2 PREVIOUS MONITORING NETWORKS 95 9.2.1 SURVEY EQUIPMENT 95 9.2.2 METHODOLOGY AND ACCURACY 95 9.3 CURRENT NETWORK 97 9.3.1 SURVEY EQUIPMENT 97 9.3.2 METHODOLOGY AND ACCURACY 97 10. EVALUATION OF JULY 27, 1987 TOPPLING FAILURE . . . 101 10.1 LOCATION OF FAILURE 101 10.2 MONITORING AND DRAINAGE NETWORK IN PLACE . . 101 10.3 PRE-FAILURE DEVELOPMENTS 108 10.4 CAUSES OF THE TOPPLING FAILURE 109 10.5 REMEDIAL MEASURES TAKEN I l l V 1 1 . E V A L U A T I O N OF S E P T 18 , 1988 T O P P L I N G F A I L U R E . . . 113 1 1 . 1 L O C A T I O N OF F A I L U R E 113 1 1 . 2 MONITORING AND DRAINAGE NETWORK I N P L A C E . . 116 1 1 . 3 P R E - F A l L U R E DEVELOPMENTS 125 1 1 . 4 CAUSES OF T H E T O P P L I N G F A I L U R E 126 1 1 . 5 R E M E D I A L MEASURES T A K E N 127 1 2 . A N A L Y S I S OF T H E MARMOT V E R T I C A L L I M B F A I L U R E . . . 128 1 2 . 1 INTRODUCTION AND BACKGROUND M A T E R I A L . . . . 128 1 2 . 2 THEORY OF UDEC ( U N I V E R S A L D I S T I N C T ELEMENT CODE) 130 1 2 . 3 PARAMETERS USED IN THE STUDY 132 1 2 . 4 S I M U L A T I O N S RUN 134 1 2 . 5 CONCLUSIONS AND RECOMMENDATIONS FOR FURTHER WORK 153 1 3 . SUMMARY AND CONCLUSIONS 157 14 . B I B L I O G R A P H Y 162 A P P E N D I X A A p p r o x i m a t e r o c k s t r e n g t h c l a s s i f i c a t i o n . . . . 166 A P P E N D I X B O p e r a t i o n a l p r o c e d u r e s f o r t h e V e r t i c a l L i m b . . 168 A P P E N D I X C S t r u c t u r a l d a t a a n d p l o t s f o r b e d d i n g i n t h e V e r t i c a l l i m b 174 A P P E N D I X D S t r u c t u r a l d a t a a n d p l o t s f o r j o i n t s i n t h e V e r t i c a l l i m b 179 A P P E N D I X E S t r u c t u r a l d a t a a n d p l o t s f o r f a u l t s i n t h e V e r t i c a l l i m b 184 A P P E N D I X F S t r u c t u r a l d a t a a n d p l o t s f o r m a j o r d i s c o n t i n u i t i e s i n t h e V e r t i c a l l i m b 186 A P P E N D I X G M o n i t o r i n g D a t a f o r t h e J u l y 2 7 , 1987 F a i l u r e . . 189 A P P E N D I X H M o n i t o r i n g D a t a f o r t h e S e p t 1 8 , 1988 F a i l u r e . . 207 A P P E N D I X I UDEC p l o t s f o r t h e 2 x 6 m c a s e w i t h no s t e p . . 224 v i A P P E N D I X J UDEC p l o t s f o r t h e A P P E N D I X K UDEC p l o t s f o r t h e A P P E N D I X L UDEC p l o t s f o r t h e A P P E N D I X M UDEC p l o t s f o r t h e A P P E N D I X N UDEC p l o t s f o r t h e A P P E N D I X 0 UDEC p l o t s f o r t h e 2 x 6 m c a s e w i t h a i m s t e p . 232 2 x 6 m c a s e w i t h a 2 m s t e p . 24 0 2 x 6 m c a s e w i t h a 3 m s t e p . 2 45 2 x 10 m c a s e w i t h no s t e p . . 249 2 x 10 m c a s e w i t h 2 . 5 m s t e p 256 2 x 10 m c a s e a w i t h 5 m s t e p 2 60 v i i L I S T OF T A B L E S T a b l e 1 E n g i n e e r i n g p r o p e r t i e s o f d i f f e r e n t m a t e r i a l s 14 T a b l e 2 Summary o f t h e s t r i k e s a n d d i p s o f t h e d i f f e r e n t j o i n t s e t s 41 T a b l e 3 W a t e r t a b l e l e v e l s i n t h e V e r t i c a l L i m b . . . 49 T a b l e 4 V a l u e s u s e i n e q u a t i o n 7 . 5 . 2 . 1 a n d t h e r e s u l t i n g r a d i a l d i s t a n c e s f r o m t h e b l a s t a t w h i c h r o c k w i l l b r e a k 71 T a b l e 5 T h e s i x d i f f e r e n t s t a g e s o f m o n i t o r i n g a n d t h e i r r e s p e c t i v e t h r e s h o l d movement r a t e s . . 94 T a b l e 6 P r i s m s l o c a t e d i n t h e f a i l u r e a r e a a n d t h e i r movement r a t e s 104 T a b l e 7 P r i s m s l o c a t e d i n t h e f a i l u r e a r e a a n d t h e i r movement r a t e s j u s t p r i o r t o t h e e v e n t 117 T a b l e 8 Summary o f s i m u l a t i o n s u s i n g UDEC . . . . . . 147 v i i i L I S T OF F I G U R E S F i g u r e 1 O w n e r s h i p o f Q u i n t e t t e C o a l L t d 1 F i g u r e 2 Q u i n t e t t e C o a l L t d . d e v e l o p m e n t 5 F i g u r e 3 G e n e r a l s t r a t i g r a p h i c s e c t i o n , Q u i n t e t t e p r o p e r t y ( S t a c e y , 1981) 8 F i g u r e 4 R e g i o n a l G e o l o g y 10 F i g u r e 5 G e o l o g i c a l c r o s s - s e c t i o n o f t h e V e r t i c a l L i m b 12 F i g u r e 6 P i t a f t e r t h e S e p t e m b e r f a i l u r e 19 F i g u r e 7 C r e s t a r e a r e - c o n t o u r e d , t o r e d u c e t h e p o s s i b i l i t y o f a t o p p l i n g f a i l u r e o c c u r r i n g a g a i n . B e l o w t h e c r e s t , damage t o t h e w a l l c a u s e d b y t h e J u l y 2 7 , 1987 f a i l u r e c a n b e s e e n 2 4 F i g u r e 8 S e c t i o n s h o w i n g a r e a t o b e s u b b e d 25 F i g u r e 9 P r o p o s e d t i m e s c h e d u l e ( C a v e r s , 1 9 8 7 ( F ) ) . . 27 F i g u r e 10 A demag s u b b i n g c o a l . 28 F i g u r e 11 T h e S e p t e m b e r 18 , 1988 F a i l u r e 3 0 F i g u r e 12 S t a b i l i t y Modes ( C a v e r s , 1 9 8 7 ( D ) ) 35 F i g u r e 13 C o n t o u r p l o t f o r p o l e s t o b e d d i n g i n t h e n o r t h w a l l 39 F i g u r e 14 C o n t o u r p l o t o f p o l e s t o J o i n t s i n t h e n o r t h w a l l . 40 F i g u r e 15 R o s e d i a g r a m o f p o l e t r e n d f o r j o i n t s i n t h e n o r t h w a l l o f t h e V e r t i c a l L i m b . . . . 41 F i g u r e 16 P l o t o f p o l e s t o f a u l t s i n t h e M a r m o t V e r t i c a l L i m b 43 F i g u r e 17 P l o t o f m a j o r d i s c o n t i n u i t i e s l o c a t e d o n t h e n o r t h w a l l o f t h e V e r t i c a l L i m b 44 F i g u r e 18 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 ( F r e e z e a n d C h e r r y , 1979) . . . 47 i x F i g u r e 19 F i g u r e 2 0 F i g u r e 21 F i g u r e 22 F i g u r e 23 F i g u r e 24 F i g u r e 25 F i g u r e 2 6 F i g u r e 27 F i g u r e 2 8 F i g u r e 2 9 F i g u r e 3 0 F i g u r e 31 F i g u r e 32 F i g u r e 33 S e c t i o n t h r o u g h a s l o p e s h o w i n g h o r i z o n t a l d r a i n s (a) a n d a d r a i n a g e g a l l e r y (b) . . . 53 M e c h a n i c s o f a b l a s t ( S p e r l i n g , 1985) . . 61 B l a s t p a t t e r n f o r t h e 1735 b e n c h i n c r o s s -s e c t i o n (a) a n d t h e p r o p o s e d b l a s t d e s i g n f o r t h e 1720 b e n c h (b) ( H a w l e y , 1984) . . . 65 P l o t o f p a r t i c l e v e l o c i t i e s i n d u c e d a t g i v e n d i s t a n c e s b y p a r t i c u l a r c h a r g e s f o r a v e r a g e s t r e n g t h r o c k (Hoek a n d B r a y , 1981) . . . . 70 S k e t c h s h o w i n g d e s i g n o f h i g h c a p a c i t y a n c h o r s ( C a v e r s , 1 9 8 8 ( c ) ) 78 T r a n s l a t i o n a l movement a l o n g a v e r t i c a l j o i n t ( C a v e r s , 1 9 8 7 ( D ) ) 80 S c h e m a t i c c r o s s - s e c t i o n s h o w i n g b o l t i n g p a t t e r n f o r n o r t h a n d s o u t h w a l l s ( C a v e r s , 1987 (D)) 82 T e n s i o n c r a c k d i s p l a c e m e n t m o n i t o r i n g t o o l ( S p e r l i n g , 1985) 87 Common f a i l u r e modes i n o p e n p i t s , a n d t h e i r r e s u l t a n t v e c t o r o r i e n t a t i o n s ( S p e r l i n g , 1985) 88 P l o t o f c u m u l a t i v e movement v e r s u s t i m e . T h e s l o p e o f t h e c u r v e c h a n g e s a s movements a c c e l e r a t e t o f a i l u r e 90 S u r f a c e e x t e n s o m e t e r t o m e a s u r e c r a c k o p e n i n g ( H a w l e y , P . M . e t a l . , 1985) . . . . 92 C u m u l a t i v e movement v s t i m e p l o t s h o w i n g v e r y l i t t l e o s c i l l a t i o n i n t h e h o r i z o n t a l movement c u r v e a n d o n l y some i n t h e v e r t i c a l movement c u r v e 100 M a r m o t V e r t i c a l L i m b n o r t h w a l l , s h o w i n g s l i d e a r e a 102 C r o s s - s e c t i o n o f J u l y 2 7 , 1987 t o p p l i n g f a i l u r e a l o n g s e c t i o n 34900 103 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 50401 a n d 1 7 5 0 - 0 3 106 x F i g u r e 34 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 1 7 5 0 - 0 4 a n d 1 7 2 0 - 0 5 107 F i g u r e 35 V e r t i c a l L i m b , n o r t h w a l l , s h o w i n g s l i d e a r e a 114 F i g u r e 3 6 C r o s s - s e c t i o n o f S e p t e m b e r 18 , 1988 t o p p l i n g f a i l u r e a l o n g s e c t i o n 34850 115 F i g u r e 37 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 175006 a n d 7901 119 F i g u r e 38 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 172501 a n d 7902 120 F i g u r e 3 9 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 7601 a n d 7404 121 F i g u r e 40 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 7051 a n d 7903 122 F i g u r e 41 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 7602 a n d 7603 123 F i g u r e 42 M a r m o t V e r t i c a l L i m b : B e d d i n g J o i n t S p a c i n g 2m, J o i n t S p a c i n g 6m, lm s t e p . B e f o r e e x c a v a t i o n 135 F i g u r e 43 M a r m o t V e r t i c a l L i m b : B e d d i n g J o i n t S p a c i n g 2m, J o i n t S p a c i n g 6m, lm s t e p 13 6 F i g u r e 44 M a r m o t V e r t i c a l L i m b : X v e l v s M a c h i n e T i m e a t t h e 1720m b e n c h c r e s t 137 F i g u r e 45 M a r m o t V e r t i c a l L i m b : X - D i s p l a c e m e n t v s T i m e a t t h e 1720m b e n c h c r e s t 138 F i g u r e 4 6 M a r m o t V e r t i c a l L i m b : B l o w up o f v e l o c i t y a c t i n g a t t h e c e n t r o i d o f e a c h b l o c k . . . . 140 F i g u r e 47 M a r m o t V e r t i c a l L i m b : B e d d i n g J o i n t S p a c i n g 2m, J o i n t S p a c i n g 6m, 2m s t e p 141 F i g u r e 48 M a r m o t V e r t i c a l L i m b : B e d d i n g J o i n t S p a c i n g 2m, J o i n t S p a c i n g 6m, 3m s t e p 142 F i g u r e 49 M a r m o t V e r t i c a l L i m b : B e d d i n g J o i n t S p a c i n g 2m, J o i n t S p a c i n g 6m, no s t e p 143 F i g u r e 50 M a r m o t V e r t i c a l L i m b : B e d d i n g J o i n t S p a c i n g 2m, J o i n t S p a c i n g 10m, no s t e p 144 x i F i g u r e 51 M a r m o t V e r t i c a l L i m b : B e d d i n g J o i n t S p a c i n g 2m, J o i n t S p a c i n g 10m, 2 .5m s t e p 145 F i g u r e F i g u r e F i g u r e F i g u r e F i g u r e F i g u r e Plate 1 52 53 54 55 56 M a r m o t V e r t i c a l L i m b : B e d d i n g J o i n t S p a c i n g 2m, J o i n t S p a c i n g 10m, 5m s t e p 146 M a r m o t V e r t i c a l L i m b : X v e l v s M a c h i n e T i m e a t t h e 1720m b e n c h c r e s t . C y c l e s = 13000 M a r m o t V e r t i c a l L i m b : Y v e l v s M a c h i n e T i m e a t t h e 1720m b e n c h c r e s t . C y c l e s = 13000 M a r m o t V e r t i c a l L i m b : X v e l v s M a c h i n e T i m e a t t h e 172 0m b e n c h C r e s t . C y c l e s - 66000 M a r m o t V e r t i c a l L i m b : Y v e l v s M a c h i n e T i m e a t t h e 1720m b e n c h c r e s t . C y c l e s = 66000 57 C h a r t o f g e o m e t r i e s a n d p a r a m e t e r s u s e d -Marmot Ver t i ca l Limb As B u i l t Wall - October 16, 1987 149 150 151 152 154 x i i ACKNOWLE DGEMENT I w i s h t o t h a n k P r o f e s s o r C O . B r a w n e r f o r h i s s u p p o r t i n a l l s t a g e s o f t h i s t h e s i s . H i s i n t e r e s t i n my w o r k a n d t h e c r i t i c a l r e v i e w s o f t h e t h e s i s d r a f t s w e r e g r a t e f u l l y a p p r e c i a t e d . I w o u l d l i k e t o e s p e c i a l l y t h a n k Q u i n t e t t e C o a l L t d . f o r t h e i r e n t h u s i a s t i c c o o p e r a t i o n ; i n p a r t i c u l a r , M r . J a c k T u o m i who p e r m i t t e d t h e a u t h o r t o u s e a l l t h e i n f o r m a t i o n g a t h e r e d i n t h e summer o f 1 9 8 8 , a n d t o u s e i n f o r m a t i o n g a t h e r e d o v e r t h e l a s t f i v e y e a r s o f o p e r a t i o n . I g r a t e f u l l y a c k n o w l e d g e M r . H a r d y B a r t l e , M r . L l o y d P e n d l e t o n a n d M r . C o l i n B u r r i d g e o f t h e G e o t e c h n i c a l D e p a r t m e n t f o r t h e i r h e l p a n d i n t e r e s t i n t h i s t h e s i s . I w i s h t o e x p r e s s s i n c e r e a p p r e c i a t i o n t o D r . K . W . S a v i g n y f o r p e r m i t t i n g t h e a u t h o r t o u s e t h e c o m p u t e r p r o g r a m U D E C . S p e c i a l t h a n k s t o M r . M a r k P r i t c h a r d f o r h i s h e l p f u l s u g g e s t i o n s a n d g u i d a n c e when t h e a u t h o r was w o r k i n g o n t h e c o m p u t e r s i m u l a t i o n . I w o u l d l i k e t o t h a n k t h e C y a n d E m e r a l d K e y s M e m o r i a l S c h o l a r s h i p F u n d f o r t h e i r f i n a n c i a l s u p p o r t , w h i c h was a c c e p t e d w i t h warm t h a n k s . F i n a l l y , I w i s h t o d e d i c a t e t h i s t h e s i s t o D e n i s e V o n n e z . W i t h o u t h e r s u p p o r t t h i s t h e s i s c o u l d n o t h a v e b e e n c o m p l e t e d . x i i i 1. INTRODUCTION 1 .1 Q U I N T E T T E COAL L T D . D e v e l o p m e n t o f t h e Q u i n t e t t e c o a l m i n e was a u t h o r i z e d i n e a r l y 1 9 8 2 , a n d i n D e c e m b e r o f 1983 t h e f i r s t s h i p m e n t o f c o a l was made . O w n e r s h i p o f Q u i n t e t t e i s h e l d b y s i x p a r t i e s , w i t h D e n i s o n M i n e s , a C a n a d i a n - o w n e d company a n d o p e r a t o r o f t h e m i n e , h a v i n g a 50% i n t e r e s t i n t h e p r o j e c t . See F i g u r e 1 f o r t h e b r e a k down o f o w n e r s h i p . — DcniMii i Mines Limited S0% Mitsui Mining IJ >% — Tokyo lioeki IIM? % —1 1—Japjnoc Sted InJuMrv 1(1% Uurbonn.Kje dc Hranee 12.01% — ' — stimiiiunit U)fjioruiui) S"u Figure 1 O w n e r s h i p o f Q u i n t e t t e C o a l L t d . T h e c o n t r a c t s w i t h t h e J a p a n e s e s t e e l c o m p a n i e s a r e f o r t h e d e l i v e r y o f 5 m i l l i o n t o n n e s , ± 5 % , o f m e t a l l u r g i c a l g r a d e c o a l e v e r y y e a r f o r 15 y e a r s w i t h a n o p t i o n f o r t h e J a p a n e s e t o c o n t i n u e r e c e i v i n g c o a l f o r a n a d d i t i o n a l 5 y e a r s . 1 1.2 PURPOSE AND SCOPE OF THE WORK T h e Q u i n t e t t e o p e n p i t m i n e c o n s i s t s o f f o u r p i t s ; S h i k a n o , W o l v e r i n e , M e s a a n d M a r m o t . I n b o t h 1987 a n d 1989 Q u i n t e t t e C o a l L t d . h a d a t o p p l i n g f a i l u r e i n t h e M a r m o t V e r t i c a l L i m b . T h e f i r s t e v e n t o c c u r r e d o n J u l y 2 7 , 1 9 8 7 , a n d a l t h o u g h m i n o r , d i s r u p t e d o p e r a t i o n s f o r a p e r i o d o f 2 m o n t h s . One y e a r l a t e r o n S e p t e m b e r 18 , 1988 a m a j o r t o p p l i n g f a i l u r e o c c u r r e d , w h i c h r e s u l t e d i n c o a l b e i n g l o s t , a n d a g a i n d i s r u p t e d o p e r a t i o n s . T h e p u r p o s e o f t h i s t h e s i s i s t o a n a l y z e a l l t h e d a t a f r o m t h e two f a i l u r e s , d e t e r m i n e t h e r e a s o n s f o r f a i l u r e a n d m o d i f y UDEC ( U n i v e r s a l D i s t i n c t E l e m e n t Code) t o e v a l u a t e t o p p l i n g f a i l u r e s . Q u i n t e t t e w i l l i n t h e f u t u r e b e m i n i n g i n a s i m i l a r g e o l o g i c s t r u c t u r e a n d l i t h o l o g y , s o t h e l e s s o n s l e a r n e d i n t h e V e r t i c a l L i m b a r e v a l u a b l e i n p r e v e n t i n g f u t u r e t o p p l i n g f a i l u r e s . T h e a r e a s i n v e s t i g a t e d w e r e : 1. T h e i n f l u e n c e o f l i t h o l o g y , s t r u c t u r a l g e o l o g y , m i n e d e s i g n , g r o u n d w a t e r , a n d b l a s t i n g o n s t a b i l i t y . 2 . T h e m i n e a n d m o n i t o r t e c h n i q u e u s e d a n d i t s e f f e c t i v e n e s s . 3 . T h e e v a l u a t i o n o f t h e J u l y 2 7 , 1987 t o p p l i n g f a i l u r e , a n d t h e r e m e d i a l m e a s u r e s t a k e n . 4 . T h e e v a l u a t i o n o f t h e S e p t e m b e r 1 8 , 1988 t o p p l i n g f a i l u r e , a n d t h e r e m e d i a l m e a s u r e s t a k e n . 2 5 . T h e b a c k a n a l y s i s o f t h e S e p t e m b e r 1 8 , 1988 f a i l u r e u s i n g t h e U n i v e r s a l D i s t i n c t E l e m e n t C o d e , w h i c h i s a new t o o l f o r s i m u l a t i n g t h e b e h a v i o u r o f a j o i n t e d r o c k m a s s . P r e v i o u s w o r k w i t h UDEC h a s b e e n i n s u c h a r e a s a s , t u n n e l d e s i g n , f l o w o f g r o u n d w a t e r t h r o u g h a f r a c t u r e d m e d i a b e n e a t h a dam a n d m o d e l l i n g t h e r m a l - m e c h a n i c a l p r o b l e m s . T h e p r o g r a m h a s b e e n c o m p a r e d t o t h e L i m i t E q u i l i b r i u m a n a l y s i s , w h i c h i s c u r r e n t l y t h e r e c o g n i z e d m e t h o d o f a n a l y z i n g t o p p l i n g f a i l u r e s , b u t t h i s i s t h e l i m i t o f w o r k d o n e . T h e o b j e c t i v e o f t h i s s t u d y i s t o a n a l y z e a l l t h e d a t a a v a i l a b l e , a n d u s e t h e i n f o r m a t i o n t o s i m u l a t e , a s c l o s e l y a s p o s s i b l e , t h e c o n d i t i o n s t h a t e x i s t e d i n t h e w a l l a t t h e t i m e o f f a i l u r e . T h e s i m u l a t i o n c a n t h e n b e u s e d t o d e t e r m i n e u n d e r w h a t c o n d i t i o n s UDEC p r e d i c t s f a i l u r e . 3 2 . S I T E CONDITIONS 2 . 1 L O C A T I O N AND A C C E S S Q u i n t e t t e C o a l L i m i t e d i s l o c a t e d i n t h e R o c k y M o u n t a i n f o o t h i l l s b e l t o f n o r t h e a s t e r n B r i t i s h C o l u m b i a , 5 5 ° 0 0 ' N a n d 1 2 1 ° 0 8 ' W. T h e W o l v e r i n e , M a r m o t a n d M e s a p i t s a r e l o c a t e d a t t h e t o p o f S h e r i f f m o u n t a i n a n d a r e c o n n e c t e d t o t h e P l a n t s i t e , w h i c h i s s i t u a t e d i n t h e v a l l e y , b y a 13 Km l o n g c o n v e y o r ( F i g u r e 2 ) . T h e n e a r e s t t o w n , w h i c h s e r v e s Q u i n t e t t e , i s T u m b l e r R i d g e 20 km t o t h e e a s t . D i s t a n c e s a n d d i r e c t i o n s o f o t h e r s u r r o u n d i n g c o m m u n i t i e s a r e : P r i n c e G e o r g e 160 km t o t h e s o u t h e a s t , Dawson C r e e k 106 km t o t h e n o r t h e a s t a n d C h e t w y n d 90 km t o t h e n o r t h . 2 . 2 PHYSIOGRAPHY T h e m a i n p i t s a r e l o c a t e d a t a p p r o x i m a t e l y 1700 m e l e v a t i o n a n d t h e t e r r a i n i s r e a s o n a b l y r u g g e d . T h e e n t i r e a r e a h a s b e e n a f f e c t e d b y a l p i n e a n d v a l l e y g l a c i a t i o n , w h i c h h a s l e f t g l a c i a l d e p o s i t s i n t h e l o w l a n d s . R e l i e f i n a n d a r o u n d t h e m i n e a r e a v a r i e s f r o m a l o w o f 1000 m a t t h e P l a n t s i t e t o a h i g h o f 1760 m a t t h e t o p o f w h a t was o n c e S h e r i f f M o u n t a i n , now c a l l e d M a r m o t / M e s a . 4 \ II (D to O c H-r r (D r t r t (0 o 0 t"1 rt a. < (D M O TJ 3 (I) r t RAIL D I S T A N C E S : P L A N T SITE - A N Z A C I 3 6 km A N Z A C - P R . G E O R G E I 2 4 km P R . G E O R G E - P R . R U P E R T 7 4 0 km 1 I I 2 3 4 k n QUINTETTE COAL LIMITED AREA DEVELOPMENT DECEMBER 1986 2 . 3 S U R F A C E HYDROLOGY T h e m i n e a r e a i s n a t u r a l l y d r a i n e d o n a l l t h r e e s i d e s b y g u l l e y s t h a t c o l l e c t t h e s u r f a c e w a t e r . T h e d r a i n a g e p a t t e r n s o n t h e m o u n t a i n s l o p e s a r e d e n d r i t i c a n d t r e n d t o t h e n o r t h w e s t , n o r t h a n d s o u t h e a s t . W a t e r , w h i c h a f f e c t s w a l l s t a b i l i t y , was a m i n o r p r o b l e m d u r i n g t h e i n i t i a l s t a g e s o f m i n i n g b e c a u s e e x c a v a t i o n b e g a n a t t h e t o p o f t h e m o u n t a i n . Now, f i v e y e a r s a f t e r p r o d u c t i o n b e g a n , w a t e r was e n c o u n t e r e d when p r o d u c t i o n b l a s t h o l e s w e r e d r i l l e d . T h i s means t h a t d u r i n g r a i n y p e r i o d s a n d s p r i n g t h a w w a t e r i s a b l e t o p e r c o l a t e downward t h r o u g h t h e p i t w a l l , a n d t h i s h a s t h e e f f e c t o f d e s t a b i l i z i n g t h e s l o p e . T h e s u r f a c e m a t e r i a l s c o v e r i n g t h e r o c k a r e t h i n t o n o n e x i s t e n t . S u r f a c e r u n o f f h a s d i r e c t a c c e s s t o t h e u n d e r l y i n g m a t e r i a l s , a n d t h e r e i s no way o f p r e v e n t i n g t h i s . W h e r e t h e p i t w a l l s h a v e some h e i g h t , g r o u n d w a t e r d i s c h a r g e s i n t o t h e p i t , b u t t h e q u a n t i t i e s a r e s m a l l . L a t e r a s t h e p i t g o e s d e e p e r i n f l o w s c o u l d become more o f a p r o b l e m . A l r e a d y , w h e r e d r a i n a g e h a s b e e n i n s t a l l e d , r e a s o n a b l e q u a n t i t i e s o f w a t e r w i l l d i s c h a r g e a f t e r a r a i n f a l l . 6 2 . 4 C L I M A T I C CONDITIONS T e m p e r a t u r e s r a n g e f r o m a h i g h o f 2 5 ° C t o a l o w o f - 4 0 ° C , b u t t e m p e r a t u r e s c a n b e r e l a t i v e l y warm i n w i n t e r i f t h e C h i n o o k e x t e n d s t h a t f a r n o r t h . T h i s c a n l e a d t o p r e m a t u r e t h a w i n g o f snow a n d c a u s e i n s t a b i l i t y i n t h e p i t w a l l s d u r i n g t h e w i n t e r m o n t h s . P r e c i p i t a t i o n f o r t h e y e a r i s a p p r o x i m a t e l y 650 mm w i t h m o s t o f t h e p r e c i p i t a t i o n o c c u r r i n g b e t w e e n J u n e a n d O c t o b e r . F o g c a n b e a p r o b l e m a n d may l i n g e r f o r a week o r l o n g e r . T h i s c a u s e s p r o b l e m s f o r o p e r a t i o n s , a n d makes v i s u a l o b s e r v a t i o n s a n d s u r v e y i n g d i f f i c u l t , i f n o t i m p o s s i b l e . 7 3 . GEOLOGY T h e m a j o r c o a l r e s o u r c e s i n t h e f o o t h i l l s o f n o r t h e a s t e r n B r i t i s h C o l u m b i a o c c u r i n two i n t e r v a l s , t h e G e t h i n g F o r m a t i o n a n d G a t e s Member , w h i c h a r e o f e a r l y C r e t a c e o u s a g e . T h e C o a l T a s k F o r c e o f 1976 e s t i m a t e d t h a t t h e s e two i n t e r v a l s h a d c o a l r e s e r v e s o f 7719 m e g a t o n s w i t h t h e G a t e s Member m a k i n g up 5350 m e g a t o n s ( S t o t t , 1 9 7 4 ) . T h e G a t e s Member i s p a r t o f t h e C o m m o t i o n F o r m a t i o n , w h i c h i s -p a r t o f t h e F o r t S t . J o h n G r o u p , a n d t h e G e t h i n g F o r m a t i o n i s p a r t o f t h e B u l l h e a d G r o u p . S e e F i g u r e 3 f o r t h e g e o l o g i c s e c t i o n , a n d F i g u r e 4 f o r t h e r e g i o n a l g e o l o g y . T h e B u l l h e a d a n d F o r t S t . J o h n F o r m a t i o n s e d i m e n t s a r e i n t e r p r e t e d a s h a v i n g b e i n g l a i d down u n d e r m a r i n e , t e r r e s t r i a l a n d t r a n s i t i o n a l e n v i r o n m e n t s o f d e p o s i t i o n ( S t o t t , 1 9 6 8 ) . T h e n o n - m a r i n e s e d i m e n t s a r e t y p i f i e d b y c o a l a n d a s s o c i a t e d c a r b o n a c e o u s p l a n t b e a r i n g s h a l e s , s i l t s t o n e s w i t h i n t e r c a l a t e d c o a r s e g r a i n e d s a n d s t o n e s a n d c o n g l o m e r a t e s . 8 CO ZD o L U u < u LU o Z) o o x o o Q. o SHAFTESBURY FORMATION (I2»rr> ) z o r— < a: o z o I— o o u • —!• 5 .. E (J • o o — CD 522 - • >o 1 E f o O MOOSE BAR FORMATION | 120-21Sm.) G E THING FORMATION (100 - 200m ) CADOMIN )5-45m NIKANASSIN FORMATION (150 - 450m | Interbedded gray shale and mudsfone Sandstone , conglomerate and shale with carbonaceous materials Marine shale with sideritic concretions ond mudstones A , B , C Babcock Member D, E,F I . J . K Quintette Member Cyclic alternation of interbedded gray shale and coarse to fine grain sand-stone, conglomerate and coal. Marine shale with sideritic concretions ; glauconitic sandstone at base. Bird, Skeeter-Chamberlain Middle Coal Zone Basal Coal Zone Siltstones , shales , some sandstone and coaly shale. F i g u r e 3 G e n e r a l s t r a t i g r a p h i c s e c t i o n , Q u i n t e t t e p r o p e r t y ( S t a c e y , 1 9 8 1 ) . 9 10 3 . 1 G E O L O G I C U N I T S I N THE V E R T I C A L L I M B T h e V e r t i c a l L i m b c o n s i s t s o f m a t e r i a l s f r o m t h e F o r t S t . J o h n G r o u p , a n d more s p e c i f i c a l l y t h e C o m m o t i o n F o r m a t i o n . T h e c o a l i s b e i n g m i n e d f r o m t h e G a t e s Member , b u t t h e H u l c r o s s Member h a s b e e n m i n e d i n t h e u p p e r p a r t o f t h e w a l l t o a l l o w a c c e s s t o t h e g r e a t e r d e p t h s . F i g u r e 5 shows t h e g e o l o g i c c r o s s - s e c t i o n f o r t h e M a r m o t V e r t i c a l L i m b . T h e r o c k t y p e v a r i e s w i t h t h e Member a n d a l s o w i t h i n t h e M e m b e r s . T h e m i n e d e s i g n a n d m i n i n g o p e r a t i o n s a r e d e p e n d e n t o n t h e r o c k t y p e , s o i t i s i m p o r t a n t t o h a v e a g o o d u n d e r s t a n d i n g o f t h e p h y s i c a l p r o p e r t i e s a n d c h a r a c t e r i s t i c s o f t h e r o c k m a s s . 3 . 1 . 1 HULCROSS MEMBER T h e H u l c r o s s , w h i c h i s e x p o s e d i n t h e u p p e r p a r t o f t h e n o r t h w a l l o f t h e M a r m o t V e r t i c a l L i m b , c o n s i s t s o f 74 t o 105 m o f r u b b l y o r b l o c k y , b r i t t l e , med ium t o d a r k g r e y s h a l e w i t h t h i n i n t e r b e d s o f s i l t s t o n e a n d v e r y f i n e s a n d s t o n e . T h e b a s e o f t h e Member i s r e l a t i v e l y homogeneous a n d c o n t a i n s s i d e r i t i c c o n c r e t i o n s . N e a r t h e t o p o f t h e Member t h e s a n d s t o n e a n d s i l t s t o n e i n t e r b e d s a r e m o r e p r e v a l e n t , a n d t h e H u l c r o s s m a r i n e s h a l e g r a d e s c o n f o r m a b l y i n t o t h e s h a l e , s a n d s t o n e s a n d c o n g l o m e r a t e o f t h e l o w e r B o u l d e r C r e e k M e m b e r . 11 MARMOT VERTICAL LIMB GEOTECHNICAL SECTION ALONG SECTION 34850 LEGEND P H R T ORIGINAL T O P O G R A P H Y DESIGN FINAL WALL ACTUAL FINAL W A L L (shown only where different from design ) P IEZOMETER SURVEY PRISM P R E - S H E A R B L A S T H O L E DOWEL DRAIN H O L E A C T U A L RAJAL WALL F R O M FLY- OVER OF j f W E Z 5 , 1935 COAL SEAM F i g u r e 5 G e o l o g i c a l c r o s s - s e c t i o n o f t h e V e r t i c a l L i m b , 12 T e s t i n g d o n e b y G o l d e r A s s o c i a t e s i n A p r i l o f 1982 d e t e r m i n e d t h e b a s i c f r i c t i o n a n g l e a v e r a g e d 2 7 ° , 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 a v e r a g e d 69 MPa ( 1 0 , 0 0 0 p s i ) a n d t h e u n i t w e i g h t a v e r a g e d 2 . 6 4 M g / m 3 . T a b l e 1 l i s t s t h e b a s i c f r i c t i o n a n g l e , t h e u n i a x i a l c o m p r e s s i o n s t r e n g t h a n d t h e u n i t w e i g h t f o r t h e d i f f e r e n t r o c k t y p e s f o u n d i n t h e V e r t i c a l L i m b . F r o m t h e R o c k S t r e n g t h C l a s s i f i c a t i o n p r o p o s e d b y H o e k a n d B r a y , 1 9 8 1 , t h i s r o c k w o u l d b e d e s c r i b e d a s R3 o r m o d e r a t e l y s t r o n g , s e e A p p e n d i x A . T h e r o c k i s w e a k e r t h a n t h e c l a s s i f i c a t i o n w o u l d s u g g e s t b e c a u s e t h e r e a r e l o c a l b e n t o n i t i c p a r t i n g s , w h i c h w i l l t e n d t o r e d u c e t h e s h e a r s t r e n g t h o f t h e r o c k m a s s a n d dam u p w a t e r w i t h i n t h e s l o p e a n d c r e a t e f u r t h e r i n s t a b i l i t y . F r o m t h e r e p o r t i t i s n o t known w h e t h e r t h e r o c k was t e s t e d we t o r d r y . I f t e s t e d d r y t h e s e v a l u e s w i l l b e h i g h e r t h a n f o r wet c o n d i t i o n s d u e t o t h e c l a y c o n t e n t o f t h e f o r m a t i o n a n d i n c r e a s e d c o h e s i o n . T h e r e s u l t s i n T a b l e 1 a l s o do n o t t a k e i n t o a c c o u n t b e d d i n g r o u g h n e s s w h i c h may amount t o 3 - 5 ° f o r t h e H u l c r o s s F o r m a t i o n ( C a v e r s ( A ) , 1 9 8 8 ) . 13 T a b l e 1 E n g i n e e r i n g p r o p e r t i e s o f d i f f e r e n t m a t e r i a l s . ROCK T Y P E B A S I C F R I C T I O N A N G L E i n d e g r e e s U N I A X I A L COMPRESSIVE STRENGTH p s i (MPa) U N I T WEIGHT l b / f t 3 (Mg/m : 3) C o a l 23 26 29 29 1 , 0 0 0 ( 7) 5 , 0 0 0 ( 34) 1 2 , 0 0 0 ( 83) 1 5 , 0 0 0 (103) 80 165 165 165 ( 1 . 2 8 ) ( 2 . 6 4 ) ( 2 . 6 4 ) ( 2 . 6 4 ) M u d s t o n e S i l t s t o n e S a n d s t o n e ( C o n g l o m e r a t e ) H u l c r o s s 27 1 0 , 0 0 0 ( 69) 165 ( 2 . 6 4 ) T h e s t r i k e o f t h e b e d d i n g i s a p p r o x i m a t e l y 1 4 0 ° , a n d t h e d i p r a n g e s f r o m 7 5 ° o u t o f t h e s l o p e t o a b o u t 7 3 ° i n t o t h e s l o p e . B e d d i n g j o i n t s a r e r e l a t i v e l y s m o o t h a n d p l a n a r , a n d h a v e a s p a c i n g v a r y i n g f r o m 0 . 1 m t o 0 . 3 m. A s w e l l a s b e d d i n g j o i n t s t h e r e a r e f o u r j o i n t s e t s , a n d m i n o r f a u l t s a r e p r e s e n t . T h e b e d d i n g t h i c k n e s s i n t h e H u l c r o s s i s l e s s t h e n . 1 m t o . 5 m , a n d b e c a u s e t h e r o c k i s weak a n d b r i t t l e t h e f r e q u e n c y o f j o i n t s h a s b e e n i n c r e a s e d b y p o o r b l a s t i n g p r a c t i c e s . S i n c e t h e H u l c r o s s i s made u p p r i m a r i l y o f f i n e g r a i n e d m a t e r i a l t h e f o l l o w i n g g e n e r a l c o n c l u s i o n s c a n b e made a b o u t i t s e n g i n e e r i n g p r o p e r t i e s . T h e s t r e n g t h w i l l d e c r e a s e a n d t h e d e g r e e o f j o i n t i n g w i l l i n c r e a s e w i t h d e c r e a s i n g g r a i n s i z e . F o r t h e H u l c r o s s t h e t y p e o f f a i l u r e w i l l b e c o n t r o l l e d b y t h e t y p e a n d o r i e n t a t i o n o f t h r o u g h g o i n g d i s c o n t i n u i t i e s , b e d d i n g j o i n t s a n d j o i n t s r a t h e r t h a n t h e i n t a c t r o c k ' s s h e a r s t r e n g t h . 14 3 . 1 . 2 GATES MEMBER T h e G a t e s Member makes u p m o s t o f t h e N o r t h W a l l o f t h e V e r t i c a l L i m b , a n d i s b r o k e n u p i n t o t h e U p p e r , M i d d l e a n d T o r r e n s U n i t s . U p p e r G a t e s i s d e f i n e d a s m a t e r i a l l y i n g s t r a t i g r a p h i c a l l y a b o v e c o a l seam D , a n d i s 10 - 15 m e t r e s t h i c k . T h e U p p e r G a t e s c a n b e f u r t h e r b r o k e n u p i n t o t h e B a b c o c k Member w h i c h l i e s d i r e c t l y o v e r D s e a m , b u t d o e s n o t i n c l u d e seams A , B a n d C . B a b c o c k c o n s i s t s o f t h r e e d i s t i n c t u n i t s : a d i s c o n t i n u o u s c h a n n e l c o n g l o m e r a t e , a c o n t i n u o u s l a g c o n g l o m e r a t e a n d a c o n t i n u o u s m a r i n e s a n d s t o n e . C o a l seams A , B a n d C l o c a t e d a b o v e t h e B a b c o c k U n i t a r e n o t e c o n o m i c a l l y m i n a b l e a n d a r e s e p a r a t e d b y a p r e d o m i n a n t l y s h a l e s e q u e n c e w i t h i n t e r c a l a t i n g s a n d y s h a l e o r v e r y f i n e s a n d s t o n e . T h e U p p e r G a t e s i s r e l a t i v e l y weak a n d f i s s i l e , o f p o o r q u a l i t y , a n d f o r e n g i n e e r i n g p u r p o s e s i s t r e a t e d a s H u l c r o s s . T h e M i d d l e G a t e s c o n t a i n s c o a l seams D , E , G a n d J , w h i c h a r e e c o n o m i c t o m i n e . T h e s e q u e n c e o f m a t e r i a l s h e r e a r e t h r e e r e p e a t i n g c y c l e s o f l a m i n a t e d t o medium t o f i n e -g r a i n e d s a n d s t o n e a n d g r a d e t o a c a r b o n a c e o u s s h a l e a n d c o a l . U n d e r l y i n g t h e M i d d l e G a t e s i s t h e T o r r e n s . I t c o n s i s t s o f m a s s i v e , l i g h t - g r e y , m e d i u m - g r a i n e d s a n d s t o n e s , w i t h m i n o r c a r b o n a c e o u s a n d c o n g l o m e r a t i c h o r i z o n s . T h i s U n i t l i e s b e l o w J seam a n d i s p a r t o f t h e S o u t h W a l l . 15 T h e M i d d l e G a t e s i n t h e V e r t i c a l L i m b i s c o n s i d e r e d t o b e a s t r o n g m a t e r i a l (R4) u s i n g t h e c r i t e r i a p r o p o s e d b y t h e R o c k S t r e n g t h C l a s s i f i c a t i o n a n d t h e i n f o r m a t i o n p r o v i d e d b y T a b l e 1. B e d d i n g j o i n t s u r f a c e s , e x p o s e d a s h o r t d i s t a n c e b e h i n d t h e c o a l s e a m s , t e n d t o b e r o u g h w i t h f r e q u e n t l o a d c a s t i n g a n d r i p p l e b e d d i n g p r e s e n t . L o a d c a s t i n g i s f o r m e d when t h e o v e r l y i n g s e d i m e n t s a r e h e a v y a n d v i s c o u s e n o u g h t o make i n d e n t a t i o n s i n t h e w e a k , l e s s v i s c o u s m a t e r i a l b e l o w . T h e r e s u l t i s a n u n e v e n s u r f a c e . T h i s r o u g h n e s s c o n s i d e r a b l y i n c r e a s e s t h e s h e a r s t r e n g t h f r o m 2 9 ° b y a s much a s 5 ° a l o n g t h e b e d d i n g j o i n t s . T h e s h e a r s t r e n g t h i s a l s o i n c r e a s e d , d u e t o t h e r o u g h n e s s , e v e n w h e r e t h i n c a r b o n a c e o u s c o a t i n g s e x i s t . H o w e v e r , o n t h e N o r t h w a l l , o c c a s i o n a l s m o o t h e r b e d d i n g j o i n t s e x i s t a t i n t e r v a l s o f 1 .5 t o 3 m. T h e b e d d i n g t h i c k n e s s e s v a r y f r o m a p p r o x i m a t e l y 0 .3 m i m m e d i a t e l y b e h i n d t h e c o a l seam t o 1 m o r m o r e a t d i s t a n c e s o f 1 t o 2 m b e h i n d t h e c o a l s e a m . T h e b e d s s t r i k e a p p r o x i m a t e l y 1 4 0 ° a n d h a v e d i p s o f v e r t i c a l t o s t e e p l y d i p p i n g i n t o o r o u t o f t h e w a l l . A s i n t h e H u l c r o s s , j o i n t s a r e p r e s e n t , a n d m i n o r f a u l t s e x i s t . 16 3 . 1 . 3 C O A L SEAMS I N THE MARMOT V E R T I C A L L I M B T h e U p p e r G a t e s c o n t a i n s seams A , B a n d C , b u t t h e s e a r e n o t m i n a b l e h e r e o r e l s e w h e r e i n t h e m i n i n g a r e a . I n t h e M a r m o t V e r t i c a l L i m b seams E , G a n d J a r e m i n e d b u t n o t D s e a m , w h i c h i s m i n a b l e t o t h e n o r t h w e s t w h e r e i t becomes t h i c k e r . T h e s e t h r e e seams E , G a n d J p r o d u c e m e t a l l u r g i c a l g r a d e c o a l . E seam i s up t o 10 m w i d e , b u t i s a c t u a l l y made up f r o m a n u m b e r o f seams i n c l u d i n g t h e c o a l e s c e n c e o f F s e a m . G seam i s a p p r o x i m a t e l y 2 m w i d e a n d i s c h a r a c t e r i z e d b y a r o c k p a r t i n g a n d a c o a l s p l i t i n t h e u p p e r p o r t i o n o f t h e s e a m . J seam i s n a r r o w e r t h e n E , a p p r o x i m a t e l y 8 m, b u t i s w e l l d e v e l o p e d a n d c o n t a i n s two s h a l e p a r t i n g s i n i t s l o w e r s e c t i o n . A l l t h r e e c o a l seams h a v e a n e a r v e r t i c a l d i p . 17 4. MINE DEVELOPMENT 4 . 1 CURRENT MINE PLAN I N THE V E R T I C A L L I M B M i n e d e s i g n s c o n s t a n t l y c h a n g e a s p r i c e s f l u c t u a t e a n d t h e d e m a n d s f o r c o a l i n c r e a s e o r d e c r e a s e a n d a s more r e l i a b l e g e o t e c h n i c a l d a t a i s a c c u m u l a t e d . T h i s i s t h e c a s e i n t h e V e r t i c a l L i m b . T h e a r e a t h a t i s b e i n g s t u d i e d i n t h i s t h e s i s i s t h e n o r t h e a s t w a l l b e t w e e n s e c t i o n s 3 4550 a n d 3 4 9 5 0 . T h e M a r m o t V e r t i c a l L i m b P i t a s o f t h e summer o f 1988 i s shown o n t h e p i t s t a t u s map (Plate 1 ) . a n d t h e m i n e l a y o u t i s i l l u s t r a t e d i n F i g u r e 2 . I n i t i a l p l a n s c a l l e d f o r a p i t w i t h a t o p e l e v a t i o n o f 1788 m a n d a p i t f l o o r a t 1645 m g i v i n g a n o v e r a l l s l o p e h e i g h t o f 143 m. T h i s h a s s i n c e c h a n g e d t o a t o p e l e v a t i o n o f 1765 m a n d a p i t b o t t o m e l e v a t i o n a t 1600 m g i v i n g a n o v e r a l l h e i g h t o f 165 m. T h e t o p 23 m w e r e r e m o v e d t o r e s h a p e t h e t o p o f t h e s l o p e , w h i c h h e l p e d t o s t a b i l i z e t h e t o p p l i n g f a i l u r e t h a t was o c c u r r i n g i n t h e n o s e a r e a ( l o c a t e d b e t w e e n s e c t i o n s 35000 a n d 3 5 1 5 0 ) . T h e p i t b o t t o m was d e e p e n e d , b e c a u s e d e s i g n e r s f e l t t h e w a l l c o u l d b e s t e e p e n e d . T h i s i n c r e a s e d c o a l r e c o v e r y a t l o w c o s t , b e c a u s e o f t h e v e r y low s t r i p p i n g r a t i o . D u r i n g t h e i n i t i a l s t a g e s o f m i n i n g t h e V e r t i c a l L i m b h a d a l a r g e e n t r a n c e a n d t h e p i t i t s e l f was v e r y s m a l l d u e t o t o p o g r a p h y . W i t h d e p t h t h e p i t e n t r a n c e h a s become v e r y n a r r o w , r e q u i r e s one way t r a f f i c , a n d t h e p i t i s much 18 l a r g e r . A c c e s s t o t h e V e r t i c a l L i m b f r o m t h e s o u t h e a s t w a s o n l y b y l i g h t v e h i c l e u n t i l t h e 1 6 1 0 e l e v a t i o n w a s r e a c h e d . I t w a s a t t h i s e l e v a t i o n t h a t a m a j o r t o p p l i n g f a i l u r e o c c u r r e d a n d a c c e s s f r o m t h e n o r t h w e s t w a s c u t o f f ( F i g u r e 6 ) . T h e p i t s h a p e i s r e c t a n g u l a r a n d o r i e n t e d p a r a l l e l t o t h e s t r i k e o f t h e s t r u c t u r e , h a s a l e n g t h o f a p p r o x i m a t e l y 5 0 0 m a n d a w i d t h o f 6 5 m a t u l t i m a t e p i t b o t t o m . F r o m c r e s t t o c r e s t t h e m a x i m u m w i d t h i s a p p r o x i m a t e l y 2 6 5 m . F i g u r e 6 P i t a f t e r t h e S e p t e m b e r f a i l u r e . 1 9 T h e p i t s l o p e a n g l e h a s c h a n g e d a s e x c a v a t i o n o c c u r r e d a n d p r o b l e m s d e v e l o p e d . T h e i n i t i a l m i n e d e s i g n c a l l e d f o r a n o v e r a l l s l o p e a n g l e o f 4 9 - 5 0 ° , b u t a n o v e r a l l a n g l e o f 4 5 - 4 8 ° was a c h i e v e d when t h e p i t was a t t h e 1690 m e l e v a t i o n . T h e u l t i m a t e p i t s l o p e a n g l e s a c h i e v e d a r e v a r i e d . T h e w a l l f r o m 1720 up t o t h e c r e s t i s a t a b o u t 3 5 ° d u e t o f l a t t e n i n g o f t h e s l o p e b e c a u s e o f a m i n o r t o p p l i n g f a i l u r e t h a t o c c u r r e d i n J u l y o f 1 9 8 7 . O v e r - a l l s l o p e a n g l e f r o m 1640 m t o 1720 v a r i e s f r o m 5 4 - 4 6 ° w i t h a n a v e r a g e a n g l e o f 5 0 ° , a n d t h e f i n a l 40 m e t r e s e c t i o n o f w a l l i s a t 5 7 ° . Berms a r e g e n e r a l l y 8 t o 10 m w i d e a n d b e n c h h e i g h t s v a r y f r o m 40 t o 30 t o 20 m ( F i g u r e 5 ) . 4 . 2 M I N E DEVELOPMENT UP TO MAY 1988 T h e s t u d y a r e a was n o t r e a c h e d u n t i l m i n i n g h a d e x c a v a t e d t h e 1765 m l e v e l . B e n c h e s w e r e b e i n g m i n e d i n 15 m l i f t s s o t h e s a f e t y b e r m was a t 1750 m. T h e m i n e p l a n c a l l e d f o r d o u b l e b e n c h i n g s o t h e n e x t s a f e t y b e r m was a t 1720 a n d t h e f o l l o w i n g a t 1 6 9 0 . T h e 1690 m L e v e l was r e a c h e d b y May o f 1 9 8 5 , a n d a t t h i s t i m e t h e p i t was a l i t t l e l e s s t h a n 200 m i n l e n g t h , a n d h a d a maximum d e p t h o f 75 m i n t h e s t u d y a r e a . Up t o t h i s p o i n t t h e s o u t h e a s t e r n p o r t i o n o f t h e V e r t i c a l L i m b , s o u t h e a s t o f s e c t i o n l i n e 3 4 9 0 0 , a p p e a r e d t o b e s t a b l e , b u t t o t h e n o r t h w e s t i n t h e n o s e a r e a , t o p p l i n g was o c c u r r i n g . 20 A c c o r d i n g t o s u r v e y e v i d e n c e a n d v i s u a l o b s e r v a t i o n s o f t h e s o u t h e a s t e r n p o r t i o n o f t h e V e r t i c a l L i m b , l i m i t e d movement may h a v e b e e n o c c u r r i n g , b u t t h e s e movements may h a v e b e e n d u e t o r e l a x a t i o n a n d / o r s u r v e y e r r o r . F r o m 1705 m t o 1690 m p r e s p l i t b l a s t i n g p r o d u c e d a c l e a n , v e r t i c a l , p l a n a r b e n c h f a c e . T h e w a l l a b o v e 1705 i s v e r y b l o c k y a n d r a g g e d a n d s u b j e c t t o m i n o r f a i l u r e s a n d r o c k f a l l s d u e t o p o o r b l a s t i n g p r a c t i c e s n e x t t o t h e w a l l . C r a c k i n g i n t h e n o s e a r e a h a d b e e n o b s e r v e d i n J u n e o f 1984 o n b e n c h e s 1750 a n d 1720 . One y e a r l a t e r , b a s e d o n d i s c u s s i o n s w i t h m i n e p e r s o n n e l , a n d a s i t e v i s i t b y J . H e n d r y o f P i t e a u A s s o c i a t e s , movement was f e l t t o h a v e b e e n a r r e s t e d ( S t e w a r t , 1 9 8 5 ( B ) ) , b u t f u r t h e r m o n i t o r i n g was r e c o m m e n d e d . T h e c r a c k i n g a n d s u b s i d e n c e o c c u r r e d i n a 3 m w i d e c a r b o n a c e o u s s h a l e l y z o n e , C - s e a m , j u s t b e h i n d t h e f a c e . T h i s seam d a y l i g h t s o n e i t h e r s i d e o f t h e n o s e a n d t e n s i o n c r a c k s w e r e p r e s e n t on b o t h s i d e s o f t h e z o n e . A n e x t e n s o m e t e r i n s t a l l e d o v e r t h i s z o n e i n m i d - J u l y a n d r e a d i n e a r l y S e p t e m b e r i n d i c a t e d t h e c r a c k s h a d o p e n e d up 4 0 cm. F r o m s u r v e y d a t a , movement was d e t e r m i n e d t o b e i n a s o u t h -s o u t h w e s t e r l y d i r e c t i o n . A l t h o u g h c r a c k s c o n t i n u e t o o p e n up t h e movement r a t e s a r e v e r y l o w a n d t h i s p a r t o f t h e w a l l i s n o t c o n s i d e r e d a p r o b l e m . T o t r y a n d h e l p s t a b i l i z e t h e a r e a t h e t o p h a s b e e n r e s h a p e d a n d h o r i z o n t a l d r a i n s w e r e i n s t a l l e d a few y e a r s l a t e r . T h e a r e a i s s t i l l h e a v i l y m o n i t o r e d t o d e t e r m i n e i f movement r a t e s s u d d e n l y 21 a c c e l e r a t e . A n o t h e r p r o b l e m i n t h e n o s e a r e a a t t h i s t i m e was b e n c h s c a l e . t o p p l i n g f a i l u r e s t h a t h a d o c c u r r e d a d j a c e n t t o t h e c r a c k i n g o n t h e 1750 m l e v e l , o n t h e b e n c h c r e s t s o f 1 7 5 0 , 1735 a n d 1 7 2 0 . T h e f a i l u r e s o c c u r r e d d u r i n g e x c a v a t i o n a n d w e r e b e l i e v e d t o b e d u e t o o v e r b l a s t i n g . T h e r u b b l e t h a t h a d c o l l e c t e d o n t h e 1720 b e r m was l e f t i n p l a c e t o g i v e t h e t o e some a d d e d s u p p o r t . O t h e r w i s e s a f e t y b e r m s , w h i c h a r e a l l a c c e s s i b l e b y c a t s , w e r e a n d a r e k e p t c l e a r o f t a l u s . T h e s e b e n c h s c a l e f a i l u r e s c o n t i n u e t o r a v e l a s b l o c k s come f r e e , b u t g e n e r a l l y t h e a r e a i s s t a b l e a n d n o t a p r o b l e m . T h e p i t a s o f J u l y 1986 was a t e l e v a t i o n 1650 m. F r o m a s t a b i l i t y p o i n t o f v i e w t h e w a l l i n t h e s t u d y a r e a was no d i f f e r e n t f r o m t h e y e a r b e f o r e . A s a f e t y b e r m was l e f t a t e l e v a t i o n 1660 m, s o t h e r e i s a d o u b l e b e n c h b e t w e e n 1690 a n d 1 6 6 0 . F r o m 1660 o n down Q u i n t e t t e c h o s e t o d e s c e n d i n l i f t s o f 10 m. A t t h i s p o i n t no d r a i n a g e h a d b e e n i n s t a l l e d o v e r a n y p a r t o f t h e w a l l . M i n i n g t h e n c o n t i n u e d o n down t o t h e 1640 m e l e v a t i o n a n d a s a f e t y b e r m was e s t a b l i s h e d . T h e e x c a v a t i o n o f t h e 1640 b e n c h was c o m p l e t e d b y F e b r u a r y o f 1 9 8 7 . M i n i n g u p t o t h i s s t a g e was t h e t r a d i t i o n a l t r u c k a n d s h o v e l o p e r a t i o n w h e r e t h e c o a l was e x p o s e d b y t h e P & H s h o v e l , a n d a L a t o u r n e a u L 1 0 0 0 f r o n t e n d l o a d e r w o u l d t h e n l o a d t h e c o a l i n t o t r u c k s . T h i s m e a n t o n l y c o a l down t o t h e 1600 m e l e v a t i o n c o u l d b e r e c o v e r e d . T h e u s e o f a d r a g l i n e t o e x c a v a t e c o a l seams E a n d J b e l o w 1600 m was c o n s i d e r e d a n d t h o u g h t t o h a v e m e r i t . T h e i d e a was t o h a v e t h e d r a g l i n e s i t a t t h e 1600 m e l e v a t i o n a n d s u b c o a l t o a d e p t h o f 2 3 m. T h e o n l y p r o b l e m w i t h t h i s s u g g e s t i o n was t h a t n o t e n o u g h r o o m w o u l d e x i s t a t t h e p i t b o t t o m f o r t h e d r a g l i n e t o o p e r a t e i f t h e r e w e r e t o b e s a f e t y b e r m s a t 1640 m a n d 1620 m. T h e s o l u t i o n was t o d e l e t e t h e s a f e t y b e r m a t 1620 m, a n d t o h a v e a q u a d r u p l e b e n c h , w h i c h w o u l d h a v e t o b e a r t i f i c i a l l y s u p p o r t e d . T h i s m e a n t t h a t w h i l e t h e 163 0 b e n c h was b e i n g e x c a v a t e d w o r k c r e w s h a d t o f o l l o w b e h i n d t h e s h o v e l ' s a d v a n c e a n d i n s t a l l p i t w a l l d r a i n a g e f i r s t f o l l o w e d b y r o c k b o l t s . By t h e e n d o f J u n e 1987 t h e p i t was a t e l e v a t i o n 1630 m. T h e w a l l i n t h e s t u d y a r e a h a d b e g u n t o show s i g n s o f d i s t r e s s i n t h e f o r m o f i n c r e a s e d movement r a t e s a n d t e n s i o n c r a c k s b e h i n d t h e c r e s t i n S e p t e m b e r o f 1 9 8 6 . T h e f i r s t t o p p l i n g f a i l u r e o f c o n s e q u e n c e d i d n o t o c c u r u n t i l a y e a r l a t e r i n t h e e a r l y m o r n i n g o f J u l y 2 8 , 1987 ( F i g u r e 7 ) . T h e f a i l u r e d i d n o t e x t e n d i n t o t h e n o s e a r e a a n d i n c l u d e d o n l y t h e 1750 b e n c h ; i t s l a t e r a l e x t e n t was b e t w e e n s e c t i o n 34800 a n d 3 4 9 5 0 . M i n i n g s t o p p e d w h i l e t h e s l i d e was c l e a n e d u p , a n d r e h a b i l i t a t i o n b e g u n . T h i s c o n s i s t e d o f r e s h a p i n g t h e t o p o f t h e w a l l , t h e 1750 m l e v e l became t h e c r e s t e l e v a t i o n a n d n o t 1765 m. T h e b e n c h e s w e r e c l e a r e d a n d m i n i n g c o n t i n u e d . M i n i n g o f t h e 1620 b e n c h b e g a n i n N o v e m b e r o f 1987 a n d c o n t i n u e d u n t i l t h e e n d o f A p r i l 1 9 8 8 . A g a i n w o r k 23 c r e w s h a d t o f o l l o w b e h i n d t h e s h o v e l ' s a d v a n c e t o i n s t a l l d r a i n a g e a n d r o c k b o l t s . F i g u r e 7 C r e s t a r e a r e - c o n t o u r e d , t o r e d u c e t h e p o s s i b i l i t y o f a t o p p l i n g f a i l u r e o c c u r r i n g a g a i n . B e l o w t h e c r e s t , damage t o t h e w a l l c a u s e d b y t h e J u l y 2 7 , 1987 f a i l u r e c a n b e s e e n . 24 T h e d r a g l i n e was s c h e d u l e d t o s u b c o a l when t h e p i t r e a c h e d t h e 1600 m e l e v a t i o n , s o t e s t i n g o f t h e d r a g l i n e a t t h e 1620 m e l e v a t i o n was t h o u g h t t o b e p r u d e n t ( F i g u r e 8 ) . T e s t i n g was c o n d u c t e d d u r i n g F e b r u a r y , M a r c h a n d A p r i l o f 1 9 8 8 ; t h e r e s u l t s w e r e n o t s a t i s f a c t o r y . A l t h o u g h c o a l seam E was b l a s t e d f i r s t t o make e x c a v a t i o n e a s i e r o n l y a d e p t h o f 8 m was o b t a i n e d r a t h e r t h a n t h e e x p e c t e d 23 m. T h e r e a s o n s g i v e n f o r t h i s s h o r t f a l l w e r e : t h e boom a r m was t o o s h o r t , t h e b u c k e t was t h e w r o n g w e i g h t a n d t h e i n c i d e n c e o f m a c h i n e r y b r e a k d o w n was more f r e q u e n t t h a n n o r m a l b e c a u s e a u s e d d r a g l i n e was b o u g h t . T h e d r a g l i n e was r e m o v e d f r o m t h e p i t a t t h e b e g i n n i n g o f May f o r o v e r h a u l . SOUTH WALL NORTH WALL F i g u r e 8 S e c t i o n s h o w i n g a r e a t o b e s u b b e d . 25 A t a b o u t t h i s t i m e s p r i n g t h a w was w e l l a d v a n c e d , a n d r e n e w e d c r a c k i n g a n d new c r a c k s w e r e o b s e r v e d o p e n i n g up b e h i n d t h e c r e s t o f t h e w a l l 145 m a b o v e t h e p i t f l o o r . 4 . 3 PROPOSED DEVELOPMENT FOR THE V E R T I C A L L I M B T h e i n i t i a l p l a n f o r t h e V e r t i c a l L i m b was t o s u b c o a l seams E a n d J w i t h t h e d r a g l i n e t o a d e p t h o f 23 m b e t w e e n J a n u a r y a n d M a r c h 1 9 8 8 . T h e a r e a w o u l d b e l e f t a l o n e d u r i n g s p r i n g t h a w a n d t h e h e a v y r a i n s t h a t u s u a l l y come i n J u l y . T h e n d u r i n g t h e f i r s t t h r e e weeks o f A u g u s t d r i l l i n g a n d b l a s t i n g o f t h e 1610 b e n c h w o u l d b e d o n e f o l l o w e d b y t h e r e m o v a l o f muck a n d t h e i n s t a l l a t i o n o f r o c k b o l t s a n d d r a i n a g e up t o m i d S e p t e m b e r . T h e 1600 b e n c h w o u l d t h e n b e d r i l l e d a n d b l a s t e d f o l l o w e d b y t h e r e m o v a l o f m u c k , a n d t h e p l a c e m e n t o f d r a i n a g e a n d r o c k b o l t s . T h i s w o u l d a l l b e c o m p l e t e d b y t h e f i r s t week o f N o v e m b e r when f r e e z e u p w o u l d h a v e o c c u r r e d g i v i n g a d d i t i o n a l s u p p o r t f o r t h e n e x t s t a g e o f t h e o p e r a t i o n , b l a s t i n g t h e c o a l f o l l o w e d b y s u b b i n g . S u b b i n g was t o h a v e b e e n f i n i s h e d b y J a n u a r y o f 1989 a l l o w i n g e x t r a t i m e f o r a n y f u t u r e p r o b l e m s . F i g u r e 9 shows t h e t i m e s c h e d u l e d e s c r i b e d . 26 1 9 8 8 1989 JAN FEB MAR APR WAY JVJN JUL AUO SEP OCT NOV DEC JAN FEB MAR APR 4 " »3 » ?2 7 II 4 18 2 18 30 13 27 9 22 I 15 29 1 2 28 1 0 24 7 21 5 19 2 18 30 13 27 1 3 27 10 I I I I M I I I I I I II. I I I I I I I I I I II I I I I I I I I I I SU6BINO 1830-13(7 J DRILL AND BLAST 4 VEEKS T T WEEKS ] DRILL I 820-1810 AND BOLT 1B20-I8I0 AND BLAST 4 WEEKS | MUCK AND BOLT I6J0-1800 10 W£ESS_ SUBSINO iBoo 4 . 4 A C T U A L DEVELOPMENT OF T H E V E R T I C A L LIMB A t t h e b e g i n n i n g o f May 1988 s p r i n g t h a w was w e l l u n d e r w a y , c o a l seams E a n d J h a d n o t b e e n e x c a v a t e d , c r a c k s w h e r e o p e n i n g u p b e h i n d t h e c r e s t b e t w e e n s e c t i o n s 34750 a n d 34950 a n d t h e p i t f l o o r was a t 162 0 m. T h e c o a l i n seams E a n d J b e t w e e n e l e v a t i o n s 1610 m a n d 1620 m was b a d l y n e e d e d , s o t h e d e c i s i o n was made t o t u r n a Demag f r o m a s h o v e l i n t o a b a c k h o e ( F i g u r e 1 0 ) . SUBGRADE EXCAVATION AND BACKFILLING OF THIN SEAMS F i g u r e 10 A demag s u b b i n g c o a l . A l t h o u g h t h e b a c k h o e g a v e i m m e d i a t e a c c e s s t o t h e c o a l t h i s m i n i n g m e t h o d a l s o h a s p r o b l e m s . T h e Demag c o u l d o n l y s u b 8 m, a n d t h e b e n c h h e i g h t was 10 m. T h e p r o b l e m was s o l v e d b y m a k i n g two p a s s e s o v e r t h e c o a l . D u r i n g t h e f i r s t p a s s t h e o p e r a t o r t o o k o n l y a 3 m s l i c e , a n d o n t h e s e c o n d p a s s t h e o p e r a t o r moved t h e Demag i n t o t h e 3 m t r e n c h a n d 28 s u b b e d t o a c o m b i n e d d e p t h o f 10 m. T h i s p r o c e d u r e w o r k e d f o r E s e a m , a n d o n c e t h e c o a l was e x c a v a t e d t h e 10 m t r e n c h was t h e n b a c k f i l l e d w i t h w a s t e r o c k t o i n c r e a s e t h e s t a b i l i t y o f t h e t o e a r e a o f t h e w a l l . T h e t e c h n i q u e f o r e x c a v a t i n g t h e c o a l h a d t o b e m o d i f i e d f o r J seam b e c a u s e u n l i k e E seam J i s 8 m w i d e , n o t 10 m, a n d t h e Demag n e e d s 10 m t o o p e r a t e . T h e 3 m c u t was made f i r s t , a s b e f o r e , w i t h t h e c o a l b e i n g t r a n s p o r t e d t o t h e c r u s h e r , b u t t h e 2 m w i d t h o f w a s t e r o c k was p u t i n t o E seam a s b a c k f i l l . O n c e t h e 3 b y 10 m t r e n c h was e x c a v a t e d t h e Demag was t h e n a b l e t o o p e r a t e d a t t h e 1617 l e v e l a n d e x c a v a t e t h e c o a l down t o 1610 m. M i n i n g o f t h e c o a l was s u c c e s s f u l l y c o m p l e t e d b y t h e m i d d l e o f J u n e , b u t u n l i k e t h e E seam t r e n c h t h e J seam t r e n c h was n o t b a c k f i l l e d t o a l l o w t h e 1610 b e n c h b l a s t t o be b l a s t e d t o a f r e e f a c e . D r i l l h o l e s i n t h e w a s t e r o c k w e r e d r i l l e d d u r i n g t h e s e c o n d h a l f o f J u n e , a n d t h e a r e a was b l a s t e d a t t h e e n d o f t h e same m o n t h . E x c a v a t i o n d i d n o t b e g i n u n t i l t h e 1 s t o f A u g u s t a n d was c o m p l e t e d b y S e p t e m b e r 5 t h . H o r i z o n t a l d r a i n s w e r e i n s t a l l e d r i g h t b e h i n d t h e s h o v e l a d v a n c e f o l l o w e d b y t h e i n s t a l l a t i o n o f s w e l l e x a n d d y w i d a g r o c k b o l t s , a t t h i s l e v e l . I n s t a l l a t i o n o f t h e r o c k b o l t s was s t i l l i n p r o g r e s s when t h e V e r t i c a l L i m b was c l o s e d o n S e p t e m b e r 1 7 t h . E seam h a d b e e n e x c a v a t e d u s i n g t h e t e c h n i q u e d e s c r i b e d a b o v e a n d a b o u t 50 m o f J s e a m , s t a r t i n g f r o m t h e n o r t h w e s t e n d o f t h e p i t , h a d b e e n r e m o v e d when t h e 29 V e r t i c a l L i m b was c l o s e d d u e t o h i g h movement r a t e s , w h i c h g a v e e v e r y i n d i c a t i o n o f i m m i n e n t f a i l u r e . F a i l u r e d i d i n f a c t o c c u r two d a y s l a t e r a t a p p r o x i m a t e l y 4 : 3 0 am on S e p t e m b e r 1 9 t h . T h e p i t was t h e n a b a n d o n e d u n t i l a n a s s e s s m e n t c o u l d b e made o f t h e s i t u a t i o n . F i g u r e 11 T h e S e p t e m b e r 18 , 1988 F a i l u r e . 30 T h e a r e a o f t h e p i t e f f e c t e d b y t h e f a i l u r e was i m m e d i a t e l y b e r m e d o f f , a n d n o t u n t i l F e b r u a r y o f 1989 was t h e d r a g l i n e b r o u g h t i n t o r e c o v e r a s much c o a l a s i t c o u l d s a f e l y . A f t e r t h e o v e r h a u l a n d o t h e r m o d i f i c a t i o n s t h e d r a g l i n e a c t u a l l y m a n a g e d t o s u b t o a maximum d e p t h o f 28 m, b e f o r e t h e t r e n c h w a l l s c a v e d i n . T h e e n d r e s u l t was t h e c o a l b e t w e e n 1600 a n d 1610 m was a l l r e l e a s e d i n t h e V e r t i c a l L i m b . C o a l b e n e a t h t h e 1600 m l e v e l i n E a n d J seams a n d l o c a t e d u n d e r t h e s l i d e d e b r i s was l o s t , b u t c o a l t o t h e s o u t h e a s t o f t h e s l i d e d e b r i s down t o a p p r o x i m a t e l y 1577 m was r e c o v e r e d . 4 . 5 MINE AND MONITOR METHOD T h e m i n i n g m e t h o d h a d t o c h a n g e o n c e m a j o r c r a c k i n g was o b s e r v e d a n d t h e d e c i s i o n t o h a v e a q u a d r u p l e b e n c h was m a d e . M i n i n g was now o c c u r r i n g i n a n a r e a t h a t h a d a f a c t o r o f s a f e t y c l o s e t o o n e , a n d m e a s u r e d movement r a t e s w o u l d g o v e r n w h e t h e r t h i s a r e a o f t h e p i t w o u l d b e o p e n o r c l o s e d . M o n i t o r i n g s y s t e m s c o n s i s t e d o f : e x t e n s o m e t e r s , v i s u a l i n s p e c t i o n s a n d a v e r y c o m p l e x s u r v e y n e t w o r k . P r o c e d u r e s , g o v e r n i n g t h e M i n e a n d M o n i t o r M e t h o d , w e r e d r a w n u p a n d i s s u e d t o s h i f t e r s a n d e n g i n e e r i n g s t a f f . T h e p r o c e d u r e s ( A p p e n d i x B) i n c l u d e d g u i d e l i n e s a s t o when t o c l o s e t h e a r e a , a n d w h a t h a d t o b e d o n e b e f o r e t h e a r e a c o u l d b e r e o p e n e d . 31 5 . S T R U C T U R A L GEOLOGY 5 . 1 R E G I O N A L S T R U C T U R A L GEOLOGY S t r u c t u r e i s p r i m a r i l y c o n t r o l l e d b y r e g i o n a l t h r u s t f a u l t s w h i c h h a v e b r o u g h t t h e c o a l seams t o t h e s u r f a c e . W i t h i n t h e Q u i n t e t t e p r o p e r t y , w h e r e t h e c o a l seams a r e p r e s e n t , t h e m a i n g e o l o g i c a l s t r u c t u r e s a r e b r o a d s y n c l i n e s a n d s t e e p e r a n t i c l i n e s w h i c h a r e s e p a r a t e d f r o m t h e M i n n e s G r o u p ( U p p e r J u r a s s i c ) , w h i c h i s h i g h l y d e f o r m a b l e , b y l o w t o m e d i u m a n g l e t h r u s t f a u l t s . T h e s e f a u l t s d i p t o t h e s o u t h w e s t a n d h a v e a v e r t i c a l d i s p l a c e m e n t o f up t o a p p r o x i m a t e l y 100 m. A l t h o u g h m i n o r f o l d i n g o f t h e m a j o r f o l d l i m b s i s uncommon m i n o r t h r u s t s a r e f r e q u e n t l y p a r a l l e l o r s p l a y f r o m t h e m a j o r f a u l t s . T h e s t r u c t u r e c o n t r o l s w h e r e t h e c o a l w i l l b e f o u n d a n d t h e t y p e s o f f a i l u r e t h a t c a n b e e x p e c t e d . I n t h e M e s a / M a r m o t p i t s t h e f o l d s a r e t i g h t w h i c h i n c r e a s e s t h e f r e q u e n c y o f f a u l t i n g a n d c o m p l i c a t e s t h e p r o c e s s o f l o c a t i n g b u r i e d c o a l . T h i s f o l d i n g a n d f a u l t i n g a l s o mean t h a t m o r e t h a n one t y p e o f f a i l u r e mode i s p o s s i b l e . W i t h i n t h e M e s a / M a r m o t p i t t h e s t r a t a h a s b e e n f o l d e d i n t o a s e r i e s o f n o r t h w e s t - s o u t h e a s t p l u n g i n g , o p e n f o l d s a n d h a s a s s o c i a t e d l o w a n g l e t h r u s t f a u l t s . T h e s t r u c t u r e i n t h e M a r m o t V e r t i c a l L i m b c o n s i s t s o f t h e n o r t h e a s t l i m b o f a n a n t i c l i n e , w h i c h p l u n g e s v e r t i c a l ( F i g u r e 5 ) . 32 5 . 2 S T R U C T U R A L MAPPING PROGRAMS S t r u c t u r a l m a p p i n g h a s b e e n o n g o i n g s i n c e t h e a r e a was f i r s t e x p l o r e d i n t h e e a r l y 1 9 7 0 ' s . T h e i n t e n s i t y p i c k e d up i n t h e e a r l y 1 9 8 0 ' s a s p l a n s w e r e made t o d e v e l o p t h e m i n e . I n i t i a l l y s u r f a c e m a p p i n g p r o v i d e d t h e o n l y s t r u c t u r a l i n f o r m a t i o n . L a t e r r o t a r y a n d d i a m o n d d r i l l h o l e s a d d e d t o t h a t i n f o r m a t i o n b y p r o v i d i n g c o r e a n d a l l o w i n g down h o l e g e o p h y s i c s t o b e d o n e . T h e d a t a c o l l e c t e d was u s e d t o d e t e r m i n e t h e d e s i g n o f f i n a l w a l l s , a n a l y z e p o s s i b l e f a i l u r e modes a n d l o c a t e a n d c a l c u l a t e c o a l r e s e r v e s . T h e m i n e p l a n a n d f i n a l w a l l d e s i g n i s c o n s t a n t l y c h a n g i n g a s more s t r u c t u r a l i n f o r m a t i o n i s g a t h e r e d w i t h d e p t h . 5 . 2 . 1 S T R U C T U R A L DATA AND I T S I N T E R P R E T A T I O N T h e t y p e o f i n f o r m a t i o n c o l l e c t e d i n t h e f i e l d i n c l u d e d l o c a t i o n , d i s c o n t i n u i t y t y p 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 , l e n g t h , w i d t h , s p a c i n g , l i t h o l o g y , r o c k mass h a r d n e s s a n d g r o u n d w a t e r c o n d i t i o n s . O n c e t h e d a t a i s r e c o r d e d i t m u s t t h e n b e a s s e m b l e d a n d a n a l y z e d . T h i s i s d o n e b y p l o t t i n g u p t h e p o l e s o f t h e d i f f e r e n t f e a t u r e s ; f a u l t s , j o i n t s a n d b e d d i n g o n s t e r e o n e t s , t h e s e a r e t h e n a n a l y z e d t o d e f i n e s t r u c t u r a l t r e n d s i n d i f f e r e n t a r e a s o f t h e p i t . P o s s i b l e f a i l u r e modes c a n a l s o b e d e t e r m i n e d . F o r t h e V e r t i c a l L i m b t h e s t r u c t u r e i s s t r a i g h t f o r w a r d , t h e a r e a o f c o n c e r n i s r e l a t i v e l y s m a l l , s o t h e p o s s i b l e t y p e s o f f a i l u r e a r e f e w . T h e d a t a f o r t h e 33 e n t i r e w a l l i s a n a l y z e d a n d p r e s e n t e d o n f o u r s t e r e o n e t s : (See A p p e n d i x e s C , D , E a n d F f o r s t r u c t u r a l d a t a . ) S t e r e o n e t 1 ) P l o t o f t h e p o l e s o f t h e F A U L T S , w h i c h w i l l d e t e r m i n e i f t h e r e i s a g e n e r a l t r e n d a n d how t h e y e f f e c t s t a b i l i t y . S t e r e o n e t 2 ) C o n t o u r p l o t o f t h e J O I N T o r i e n t a t i o n s . F r o m t h i s t h e s t r i k e a n d d i p o f t h e d i f f e r e n t j o i n t s e t s w i l l b e d e t e r m i n e d . S t e r e o n e t 3) C o n t o u r p l o t o f t h e BEDDING a n d BEDDING J O I N T S . T h i s w i l l g i v e a n a v e r a g e s t r i k e a n d d i p o f t h e b e d d i n g , w h i c h w i l l b e u s e d t o d e t e r m i n e w h e t h e r p l a n a r a n d t o p p l i n g f a i l u r e s a r e p o s s i b l e . S t e r e o n e t 4) T h e c e n t r o i d o f e a c h p o p u l a t i o n o f J O I N T S E T S a n d BEDDING J O I N T S i s p l o t t e d t o d e t e r m i n e w h e t h e r wedge f a i l u r e s a r e p o s s i b l e . T h i s a n a l y s i s o n l y d e t e r m i n e s t h a t c e r t a i n p e a k o r i e n t a t i o n s may l e a d t o f a i l u r e b y t h e p o s s i b l e f a i l u r e m o d e s , w h i c h f o r t h e V e r t i c a l L i m b a r e ; p l a n a r , wedge a n d t o p p l i n g ( F i g u r e 1 2 ) . T h i s d o e s n o t mean f a i l u r e w i l l o c c u r , b u t t h a t f a i l u r e i s k i n e m a t i c a l l y p o s s i b l e . F u r t h e r i n v e s t i g a t i o n w i l l d e t e r m i n e w h e t h e r t h e d i s c o n t i n u i t y i s d i p p i n g t o o s t e e p l y t o d a y l i g h t o r t h e a n g l e o f i n t e r s e c t i o n 34 MODE SCHEMATIC DRAWING NECESSARY CONDITIONS WEDGE FAILURE FLANt t 1 \ PL»N£ ' " " T ^ / " ^ wtOOC FAILURE 1 ) L I N E O F I N T E R S E C T I O N P E T W E E N P L A N E S 1 AND 2 D A Y L I G H T S ON F A C E . 2 ) FOR DRY C O N D I T I O N S , I N T E R S E C T I O N V E C T O R MUST D I P MORE S T E E P L Y T H A N A N G L E OF F R I C T I O N . PLANAR TRANSLATION TRANSNATIONAL FAILURE ON DATLIONTINO 04KONTINWTT 1 ) D I S C O N T I N U I T Y D A Y L I G H T S ( D I P I S L E S S THAN D t P O F F A C E ) . 2 ) S T R I ICE OF D I S C O N T I N U I T Y S U B - P A R A L L E L TO F A C E S T R I K E . 3 ) L A T E R A L R E L E A S E E X I S T S . «•) FOR DRY C O N D I T I O N S , D I P OF D I S C O N T I N U I T Y I S G R E A T E R T H A N A N G L E OF I N T E R N A L F R I C Y I O N . TOPPLING MULTIPLE BLOCK TOPPLINO SIMILE BLOCK TOPPLES HAY OCCUR CN ANf STEEPLY DIPPING DISCONTINUITY UNDER EXTERNAL LDADlNS, FOR MULTIPLE BLOCK TOPPLES: 1) 6ED0IN5 JOINTS OR SIMILAR, RECUL.5*, JOINT SYSTEM DIPPING INTO FACE. 2) FOR MAJOR FAILURE, STRIKE OR JOINT SYSTEM WITHIN - J0° OP FACE STRIKE. J) FOR 1 • DIP OP JOIMT SYSTEM. • • ANGLE OP FRICTION, o « DIP OP SLOPE. FOR TOPPLIKC TO OCCUR a > <»0 - « ) • • , FOR DRY CONDITIONS. " F i g u r e 12 S t a b i l i t y Modes ( C a v e r s , 1 9 8 7 ( D ) ) . 35 o f two d i s c o n t i n u i t i e s i s l e s s t h a n t h e a n g l e o f f r i c t i o n a n d s l i d i n g w i l l n o t b e p o s s i b l e u n l e s s w a t e r p r e s s u r e s e x i s t . T h e n e x t s t e p i s t o h a v e a s t a b i l i t y a n a l y s i s d o n e t a k i n g i n t o a c c o u n t s h e a r s t r e n g t h , w a l l g e o m e t r y a n d g r o u n d w a t e r c o n d i t i o n s . F i g u r e 12 shows t h e d i f f e r e n t t y p e s o f f a i l u r e modes m e n t i o n e d h e r e a n d t h e s e w i l l b e d i s c u s s e d i n d i v i d u a l l y . T h e s i m p l e s t t y p e o f f a i l u r e m e c h a n i s m i s p l a n a r o r t r a n s l a t i o n a l , w h i c h c o n s i s t s o f a r o c k mass s l i p p i n g a l o n g a s i n g l e p l a n e . F o r t h i s t o o c c u r t h e s t r i k e o f t h e p l a n e m u s t b e r o u g h l y p a r a l l e l t o t h e w a l l ( ± 2 0 ° ) , a n d t h e s h e a r s t r e n g t h o f t h e d i s c o n t i n u i t y m u s t b e o v e r c o m e . T h e s h e a r s t r e n g t h i n c l u d e s t h e c o h e s i v e s t r e n g t h a n d t h e r e s i s t a n c e o f movement d u e t o f r i c t i o n . A l a t e r a l r e l e a s e s u r f a c e i s u s u a l l y r e q u i r e d t o a l l o w t h e r o c k mass t o m o v e . Two d i s c o n t i n u i t i e s w h i c h i n t e r s e c t make u p a wedge f a i l u r e . T h e l i n e o f i n t e r s e c t i o n m u s t d a y l i g h t a n d g e n e r a l l y t h i s l i n e m u s t d i p a t a n a n g l e s t e e p e r t h a n t h e a n g l e o f f r i c t i o n i f s l i p i s t o o c c u r u n l e s s w a t e r p r e s s u r e s e x i s t . A n g l e s o f i n t e r s e c t i o n g r e a t e r t h a n t h e f r i c t i o n a n g l e c a n b e f o u n d t o b e s t a b l e i f t h e a n g l e o f i n t e r s e c t i o n d o e s n o t d a y l i g h t . T h e wedge s t a b i l i t y a n a l y s i s t a k e s i n t o a c c o u n t t h e wedge g e o m e t r y , t h e s h e a r s t r e n g t h o f t h e two d i s c o n t i n u i t i e s a n d t h e g r o u n d w a t e r c o n d i t i o n s . F r o m t h e S t r u c t u r a l m a p p i n g d o n e i n t h e s t u d y 36 a r e a t h i s t y p e o f f a i l u r e i s c o n s i d e r e d r a r e a n d w o u l d b e c o n f i n e d t o b e n c h s c a l e t y p e f a i l u r e s . T o p p l i n g , w h i c h i s t h e m o s t c r i t i c a l mode o f f a i l u r e i n t h e V e r t i c a l L i m b , o c c u r s when b e d d i n g p l a n e s d i p s t e e p l y i n t o t h e w a l l a n d t h e s t r i k e o f t h e d i s c o n t i n u i t i e s a r e a l m o s t p a r a l l e l t o t h e s l o p e . F a i l u r e o c c u r s b y t h e f o r w a r d r o t a t i o n o f b l o c k s f o r m e d b y b e d d i n g s u r f a c e s a n d j o i n t s w i t h i n t e r b l o c k s h e a r o c c u r r i n g a l o n g t h e b e d d i n g p l a n e s . T h i s t y p e o f f a i l u r e c a n o c c u r i f t h e s l o p e i s we t o r d r y i f t h e c o n d i t i o n s a r e u n f a v o u r a b l e . G e n e r a l l y t o p p l i n g i s a p r o g r e s s i v e f a i l u r e t h a t p r o p a g a t e s up h i l l a n d u s u a l l y t a k e s some t i m e t o d e v e l o p . T h i s t y p e o f f a i l u r e i s a l s o c h a r a c t e r i z e d b y t h e p r e s e n c e o f o b s e q u e n t s c a r p s , a n d v e r y h i g h s t r e s s e s a t t h e t o e . 5 . 3 S T R U C T U R A L GEOLOGY I N T H E V E R T I C A L L I M B T h e g e n e r a l s t r u c t u r e o f t h e M a r m o t V e r t i c a l L i m b i s a n e a s t l i m b o f a n n o r t h w e s t e r l y p l u n g i n g a n t i c l i n e . T h e b e d d i n g i s n e a r v e r t i c a l a n d i s c u t b y j o i n t s a n d m i n o r f a u l t s . B e f o r e a n d d u r i n g m i n i n g o p e r a t i o n s s t r u c t u r a l m a p p i n g i s d o n e , a n d i s u p d a t e d a s t h e p i t g o e s d e e p e r a n d m o r e d a t a b e c o m e s a v a i l a b l e . T h e n e x t s e c t i o n s w i l l l o o k a t t h e N o r t h W a l l i n d e t a i l , a n d w i l l a n a l y z e i t s g e o l o g i c s t r u c t u r e a n d p r e s e n t t h e p o s s i b l e t y p e s o f f a i l u r e . 37 5 . 3 . 1 BEDDING AND BEDDING J O I N T S T h e b e d d i n g i n t h e V e r t i c a l L i m b s t r i k e s s u b p a r a l l e l t o t h e l o n g a x i s o f t h e p i t a n d d i p s i n t o a n d o u t o f t h e s l o p e . T h e s t r i k e o f t h e b e d d i n g r a n g e s f r o m 1 2 0 - 1 5 0 ° a n d h a s a n a v e r a g e s t r i k e o f 1 4 3 ° . B e d d i n g d i p r a n g e s f r o m 7 5 ° S W , o u t o f t h e s l o p e , t o a b o u t 7 3 ° N E , i n t o t h e s l o p e , w i t h a n a v e r a g e d i p o f a p p r o x i m a t e l y 8 8 ° N E . F i g u r e 13 shows t h e c o n t o u r p l o t f o r b e d d i n g i n t h e n o r t h w a l l o f t h e V e r t i c a l L i m b . 5 . 3 . 2 J O I N T I N G F o u r j o i n t s e t s e x i s t i n t h e n o r t h w a l l : one r e l a t i v e l y w e l l d e v e l o p e d , one m o d e r a t e l y d e v e l o p e d a n d two p o o r l y d e v e l o p e d . F r o m F i g u r e s 14 a n d 15 t h e f o u r s e t s c a n b e d e t e r m i n e d . J o i n t s e t 1 c o n s i s t s o f r e l a t i v e l y w e l l d e v e l o p e d j o i n t s , w h i c h s t r i k e a l m o s t p e r p e n d i c u l a r t o b e d d i n g a n d h a v e a g e n e r a l d i p o f 7 0 ° t o t h e s o u t h e a s t . J o i n t s e t 2 c o n s i s t s o f m o d e r a t e l y d e v e l o p e d j o i n t s , w h i c h a l s o s t r i k e a p p r o x i m a t e l y p e r p e n d i c u l a r t o b e d d i n g , a n d t h e d i p i s a p p r o x i m a t e l y 2 0 ° t o w a r d s t h e n o r t h w e s t . T h e l a s t two J o i n t s e t s , 3 a n d 4 , a r e v e r y p o o r l y d e v e l o p e d . B o t h s t r i k e r o u g h l y e a s t w e s t . J o i n t s e t 3 d i p s m o d e r a t e l y , a b o u t 4 4 ° t o t h e n o r t h a n d j o i n t s e t 4 d i p s s l i g h t l y , 2 4 ° t o t h e s o u t h . T a b l e 2 s u m m a r i z e s t h e s t r i k e s a n d d i p s o f t h e d i f f e r e n t j o i n t s e t s . 38 CONTOUR PLOT OF POLES TO BEDDING/BEDDING JOINTS Nor t h l F T * C f e \ \ P L » * £ EHCH F A C f LEGEND ( f o r f i r s t 9 I n t e r v a l s ) UJ B EH 1-2-3-*-5-0 9-146 P o i n t s C o ntour Method: Schmidt (1925) C o u n t i n g A r e a : 0.010 Contour I n t e r v a l : Maximum C o n t o u r : 1\ P o i n t s per 1\ A r e a 66 NOTE: c o n t o u r P a t t e r n s Repeat E v e r y 9 I n t e r v a l s F i g u r e 13 C o n t o u r p l o t f o r p o l e s t o b e d d i n g i n t h e n o r t h w a l l . 39 LEGEND ( f o r f i r s t 9 i n t e r v a l s ) 86 P o i n t s m 1- 1 E3 6- 6 C o n t o u r M e t h o d : S c h m i d t ( 1 9 2 5 ) B 2- 2 0 7- 1 C o u n t i n g A r e a : 0 .010 EH 3- 3 S3 8- 8 C o n t o u r I n t e r v a l : 1% P o i n t s p e r 1% EE 4- 4 • 9- 9 Maximum C o n t o u r : 17 a 5- 5 NOTE: C o n t o u r P a t t e r n s R e p e a t E v e r y 9 I n t e r v a l s F i g u r e 14 C o n t o u r p l o t o f p o l e s t o J o i n t s i n t h e n o r t h w a l l . 40 ROSE DIAGRAM OF POL E TREND FOR J O I N T S I N THE NORTH WALL OF THE V E R T I C A L L I M B N o r t h 86 D a t a P o i n t s S i n g l e L i n e Shows V e c t o r Mean C i r c u l a r Mean = 324 d e g r e e ( s ) A n g u l a r D e v . = 3 2 . 0 5 R e s u l t a n t = 0.374 F i g u r e 15 R o s e d i a g r a m o f p o l e t r e n d f o r j o i n t s i n t h e n o r t h w a l l o f t h e V e r t i c a l L i m b . T a b l e 2 Summary o f t h e s t r i k e s a n d d i p s o f t h e d i f f e r e n t j o i n t s e t s . J o i n t S t r i k e D i p J o i n t s e t 1 5 2 ° 7 2 ° S E J o i n t s e t 2 3 4 ° 2 0°NW J o i n t s e t 3 1 0 9 ° 4 4 ° N J o i n t s e t 4 8 7 ° 2 4 ° S 41 5 . 3 . 3 F A U L T S A v e r y s m a l l number o f f a u l t s w e r e mapped a n d a s c a n b e s e e n f r o m F i g u r e 16 t h e i r o r i e n t a t i o n s w e r e s c a t t e r e d . A n y g o u g e p r e s e n t i n t h e f a u l t s t e n d s t o b e w e a t h e r e d f a u l t b r e c c i a a n d i s l e s s t h a n 2 0 cm t h i c k . A l m o s t a l l a r e s u b p a r a l l e l t o t h e p o o r l y d e v e l o p e d j o i n t s o f j o i n t s e t s 3 a n d 4 . 5 . 3 . 4 T Y P E OF F A I L U R E S A S S O C I A T E D WITH THE S T R U C T U R E T h e t h r e e p o s s i b l e t y p e s o f f a i l u r e s t h a t c a n b e d e t e r m i n e d f r o m t h e s t r u c t u r a l d a t a a r e p l a n a r , wedge a n d t o p p l i n g . F i g u r e 13 shows t h e p o l e s t o b e d d i n g , t h e t r e n d o f t h e b e n c h c r e s t a n d t h e b e n c h f a c e a n g l e . F i g u r e 13 shows t h a t k i n e m a t i c a l l y t o p p l i n g f a i l u r e i s p o s s i b l e d u e t o t h e p o l e s i n t h e s o u t h w e s t e r n c o r n e r a n d p l a n a r f a i l u r e i s p o s s i b l e d u e t o t h e p o l e s i n t h e n o r t h e a s t e r n c o r n e r . P l a n a r f a i l u r e o n l y o c c u r s i f t h e w a l l i s u n d e r c u t a n d b e d d i n g p l a n e s a r e d a y l i g h t e d . T h i s d i d o c c u r , b u t t h e f a i l u r e s c o n s i s t e d o f o n l y s m a l l s l a b s . T o p p l i n g f a i l u r e d u e t o g r a v i t y a l o n e i s n o t l i k e l y t o o c c u r , d u e t o t h e a l m o s t v e r t i c a l s t r u c t u r e o f t h e b e d s . T h i s w o u l d i n d i c a t e a n o t h e r m e c h a n i s m i s n e e d e d t o i n d u c e f a i l u r e , s u c h a s , p o o r b l a s t i n g p r a c t i c e s a n d / o r h i g h w a t e r p r e s s u r e s a c t i n g o n b e d d i n g p l a n e s . 42 F a u l t s i n t h e M a r m o t V e r t i c a l N o r t h 1 L i mb o \ j o \ J I + \ \ \ o o / / / o o / / EQUAL AREA P R O J E C T I O N F a u l t s i n t h e M a r m o t V e r t i c a l 1 L i m b S y m b o l .7 P o i n t s ••: SPLOT by Ojrton Softvars 7 P o i n t s T o t a l F i g u r e 16 P l o t o f p o l e s t o f a u l t s i n t h e M a r m o t V e r t i c a l L i m b . 43 F i g u r e 17 shows t h e p o l e s a n d t h e a s s o c i a t e d g r e a t c i r c l e f o r e a c h o f t h e j o i n t s e t s a n d b e d d i n g j o i n t s . A l s o p l o t t e d a r e t h e b e n c h c r e s t , t h e b e n c h f a c e a n g l e a n d t h e o v e r a l l w a l l a n g l e . O f a l l t h e p o s s i b l e i n t e r s e c t i o n s b e t w e e n j o i n t s e t s a n d b e d d i n g j o i n t s t h e o n l y i n t e r s e c t i o n c a u s i n g c o n c e r n i s b e t w e e n j o i n t s e t s 1 a n d 2 . T h e a r r o w shows t h e d i r e c t i o n o f m o v e m e n t , w h i c h i s a p p r o x i m a t e l y p e r p e n d i c u l a r t o t h e w a l l . T h e a n g l e o f i n t e r s e c t i o n i s o n l y 7 ° . U s i n g t h e wedge s t a b i l i t y c h a r t s f o r f r i c t i o n o n l y , p r e s e n t e d i n H o e k a n d B r a y ( 1 9 8 1 ) , t h e f a c t o r o f s a f e t y i s a p p r o x i m a t e l y 1 . 5 . T h i s d o e s n o t t a k e w a t e r i n t o a c c o u n t , b u t wedge f a i l u r e s w e r e n o t a p r o b l e m o n t h e n o r t h w a l l . 44 MAJOR D I S C O N T I N U I T I E S I N THE V E R T I C A L L I M B N o r t h I 5JT M 1 EQUAL AREA PROJECTION JOINT SET ONE NW MVL JOINT SET 2 NW MVL JOINT SET THREE JOINT SET FOUR BEDDING AND BEDDING JOINT NW MVL C o n t i n u e d on Next Page P o i n t s Point3 P o i n t s P o i n t s P o i n t s Symbol • o 0 + A F i g u r e 17 P l o t o f m a j o r d i s c o n t i n u i t i e s l o c a t e d o n t h e n o r t h w a l l o f t h e V e r t i c a l L i m b . 45 6. GROUNDWATER HYDROLOGY T h e g r o u n d w a t e r r e g i m e i n t h e V e r t i c a l L i m b i s c o m p l i c a t e d d u e t o t h e g e o l o g y a n d g e o l o g i c s t r u c t u r e . I n t h e u p p e r w a l l , a b o v e 1620 m, t h e g r o u n d w a t e r c o n s i s t s o f p e r c h e d a n d t r a n s i e n t w a t e r t a b l e s . D u r i n g t h e l a t e r s t a g e s o f m i n i n g , h o r i z o n t a l d r a i n s w e r e i n s t a l l e d t o r e d u c e t h e w a t e r p r e s s u r e s b e h i n d t h e w a l l . 6 . 1 P I E Z O M E T E R S 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 s h a v e b e e n o n g o i n g . D u r i n g t h e l a t e 7 0 ' s o l d e x p l o r a t i o n d r i l l h o l e s w e r e v i s i t e d a n d p i e z o m e t e r s a n d s t a n d p i p e s w e r e i n s t a l l e d . F a l l i n g h e a d a n d d o u b l e p a c k e r t e s t s w e r e t h e n d o n e t o d e t e r m i n e t h e h y d r a u l i c c o n d u c t i v i t y v a l u e s o f t h e v a r i o u s b e d r o c k u n i t s . H y d r o g e o l o g i c t e s t i n g was c o n t i n u e d i n t h e 8 0 ' s a n d h y d r a u l i c c o n d u c t i v i t y v a l u e s w e r e f o u n d t o r a n g e f r o m 10" 5 t o 10" 6 c m / s i n t h e m o r e p e r m e a b l e s a n d s t o n e s a n d i n z o n e s o f f r a c t u r e d o r f a u l t e d b e d r o c k . T h e s h a l e s h a d v e r y l o w h y d r a u l i c c o n d u c t i v i t y v a l u e s a t 10" 8 c m / s . T h e s e h y d r a u l i c c o n d u c t i v i t y v a l u e s f o r t h e s h a l e a n d s a n d s t o n e w o u l d a p p e a r t o b e n o r m a l , when c o m p a r e d t o v a l u e s p u b l i s h e d i n G r o u n d w a t e r b y F r e e z e a n d C h e r r y (1979) ( F i g u r e 1 8 ) . H y d r o g e o l o g i c t e s t i n g was n o t p e r f o r m e d i n t h e V e r t i c a l L i m b s p e c i f i c a l l y e x c e p t f o r t h e i n s t a l l a t i o n o f one s t a n d p i p e a n d two p n e u m a t i c p i e z o m e t e r s . 46 Rocks Unconsolidated deposits C — o o I o Q_ a) .y 0.-0 c I "O o a a> £ a> <u = 2 §1 u c O a £ a) -S ' £ u u 3 s ° lis? a QJ QJ C 5 -c o 3 E darcy) (cm2) (cm/s) ( TVS) (gal/day/f r to 5 - I O - 3 - , o 2 r i - 1 0 4 J - t o - 4 H O - -.o-' - t o 6 - 1 0 3 - I 0 " 5 - i - l O " 2 - I O 5 - I O 2 - IO" 6 - 1 0 " ' - IO" 3 - 1 0 4 -10 - I O " 7 - I 0 " 2 H O " 4 - I O 3 -1 - 10"8 - IO" 3 - IO" 5 -to 2 -10-' - I O " 9 - I O " 4 - IO" 6 - 10 -to- 2 - t 0 " ' ° - IO" 5 - IO" 7 -1 - 1 0 " 3 - 1 0 " " - 1 0 " 6 - 1 0 ' 8 - 1 0 " ' - io - 4 - 10"'2 - IO " 7 -to" 9 - I O " 2 - 10" 5 - I O " 1 3 - to' 8 - 10 " ' ° - 10"3 - IO" 6 -IO"' 4 -10' 9 -10"" -10"4 - IO" 7 -to"' 5 -10"'° -to" 1 2 - IO"5 - IO"8 -to" 1 6 -io-" -to"1 3 - tO" 6 10" F i g u r e 18 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 ( F r e e z e a n d C h e r r y , 1 9 7 9 ) . T h e s t a n d p i p e was i n s t a l l e d o n J a n u a r y 2 5 , 1987 a n d was i n o p e r a t i v e b y A p r i l 1 3 , 1 9 8 8 . T h e b o r e h o l e l o c a t e d o n s e c t i o n l i n e 35096 o n t h e c r e s t o f t h e n o r t h w a l l was d r i l l e d a t a n a n g l e o f 50 d e g r e e s f r o m t h e h o r i z o n t a l a n d t h e b o t t o m l o c a t e d 2 5 8 . 7 m b e l o w t h e g r o u n d s u r f a c e . M e a s u r e m e n t s w e r e t a k e n b y l o w e r i n g a s e n s o r down t h e h o l e a n d r e c o r d i n g t h e d e p t h a t w h i c h t h e w a t e r t a b l e was i n t e r s e c t e d . U n f o r t u n a t e l y i n A p r i l t h e s t a n d p i p e became 47 i n o p e r a t i v e when t h e s e n s o r jammed i n t h e h o l e , 240 m b e l o w t h e g r o u n d s u r f a c e . I n e a r l y D e c e m b e r two n e s t e d p n e u m a t i c p i e z o m e t e r s w e r e l o c a t e d o n t h e c r e s t a r e a o f t h e n o r t h w a l l . One e n t i r e p i e z o m e t e r s e t up f a i l e d , a n d t h e o t h e r was s t i l l f u n c t i o n i n g o n A u g u s t 9 , 1 9 8 8 , b u t was n o t r e a d j u s t p r i o r t o t h e f a i l u r e , w h i c h d e s t r o y e d t h e i n s t a l l a t i o n . T h i s p i e z o m e t e r was l o c a t e d a t e l e v a t i o n 1725 m o n s e c t i o n l i n e 3 4 8 0 0 . T h e b o r e h o l e was d r i l l e d a t a n a n g l e o f 7 5 ° f r o m t h e h o r i z o n t a l a n d t h e l o w e s t p i e z o m e t e r t i p , w h i c h was t h e o n l y t i p u n d e r t h e w a t e r t a b l e , was p l a c e d 1 4 5 . 2 m b e l o w t h e g r o u n d e l e v a t i o n . U n f o r t u n a t e l y t h e p n e u m a t i c p i e z o m e t e r a n d t h e s t a n d p i p e w e r e n o t f r e q u e n t l y r e a d . T h e s t a n d p i p e was r e a d s i x t i m e s o v e r a p e r i o d o f 15 m o n t h s , a n d o n l y i n l a t e w i n t e r a n d e a r l y s p r i n g . T h e s t a n d p i p e w h i c h was l o c a t e d a t a t o p o g r a p h i c e l e v a t i o n o f 1765 m h a d a w a t e r t a b l e a t a p p r o x i m a t e l y 162 0 m d u r i n g t h e w i n t e r m o n t h s a n d d u r i n g s p r i n g t h a w t h i s i n c r e a s e d t o 1631 m. T h e p n e u m a t i c p i e z o m e t e r was r e a d f i v e t i m e s i n 10 m o n t h s , w i t h t h r e e o f t h e r e a d i n g s t a k e n d u r i n g s p r i n g t h a w . T h e d a t a shown i n T a b l e 3 i n d i c a t e s t h e w a t e r t a b l e b e f o r e s p r i n g t h a w was a t i t s l o w e s t , b u t w i t h t h e downward p e r c o l a t i o n o f m e l t w a t e r s , t h e w a t e r t a b l e r i s e s q u i c k l y f r o m a p p r o x i m a t e l y 1588 m t o 1613 m. D u r i n g t h e we t summer m o n t h s t h e w a t e r t a b l e s l o w l y r i s e s a n d h i t s i t s h i g h p o i n t a t 163 0 m a b o u t A u g u s t t h i s i s f o l l o w e d b y a d r y e r p e r i o d a n d t h e o n s e t o f 48 f r e e z e u p . T h i s r e d u c e s r e c h a r g e c o n s i d e r a b l y a n d t h e w a t e r t a b l e b e g i n s i t s s l o w d e s c e n t . T a b l e 3 W a t e r t a b l e l e v e l s i n t h e V e r t i c a l L i m b . S t a n d p i p e QMR 87006 DATE E L E V A T I O N OF W . T . J a n 2 5 , 1987 1624 m J a n 2 7 , 1987 1624 m May 1 6 , 1987 1631 m May 2 6 , 1987 1627 m J u n 0 2 , 1987 1626 m J u n 1 0 , 1987 1624 m A p r 1 3 , 1988 I n o p e r a t i v e P i e z o m e t e r QMR 87139 DATE E L E V A T I O N OF W . T . Dec 0 5 , 1987 1618 m M a r 0 2 , 1988 1590 m M a r 2 9 , 1988 1589 m A p r 1 3 , 1988 1613 m A u g 0 9 , 1988 1627 m 6 . 2 I N T E R P R E T A T I O N OF T H E NORTH WALL HYDROLOGY T h e w a t e r t a b l e l e v e l s m e a s u r e d i n t h e V e r t i c a l L i m b a n d e l s e w h e r e i n t h e M a r m o t / M e s a p i t s u g g e s t t h e w a t e r t a b l e m i r r o r s t h e t o p o g r a p h y . T h e s i m p l i f i e d g r o u n d w a t e r f l o w m o d e l , f o r t h e V e r t i c a l L i m b , c o n s i s t s o f r e c h a r g e f r o m p r e c i p i t a t i o n i n f i l t r a t i n g t h e r o c k mass a n d p e r c o l a t i n g v e r t i c a l l y t h r o u g h u n s a t u r a t e d m a t e r i a l f l o w i n g downwards as g r o u n d w a t e r t o t h e v a l l e y d i s c h a r g e a r e a s . T h e m o d e l i s c o m p l i c a t e d b y t h e p r e s e n c e o f r e l a t i v e l y i m p e r m e a b l e 49 l i t h o l o g i c u n i t s a n d g e o l o g i c s t r u c t u r e . I n t h e V e r t i c a l L i m b t h e s a n d s t o n e u n i t s , b e d d i n g j o i n t s , j o i n t s e t s a n d c o a l a c t a s f l o w p a t h s , a n d t h e s h a l e a n d b e n t o n i t i c c l a y -l a y e r s a c t a s a q u i t a r d s . T h e s e a q u i t a r d s dam w a t e r a n d p r e v e n t s e e p a g e t o w a r d s t h e p i t , w h i c h means t h a t p e r c o l a t i n g g r o u n d w a t e r h a s t o f l o w downwards o r h o r i z o n t a l l y i n t h e d i r e c t i o n o f t h e m o u n t a i n s i d e . Due t o t h e s t r u c t u r e o f t h e r o c k mass g r o u n d w a t e r i s i s o l a t e d i n t o s t r u c t u r a l l y b o u n d e d b l o c k s w h i c h a r e u n a b l e t o d r a i n . T h i s was e v i d e n t f r o m d r a i n s d r i l l e d i n t o t h e w a l l a t t h e 162 0 m e l e v a t i o n . One d r a i n w o u l d b e p r o d u c i n g w a t e r w h i l e e q u a l l e n g t h d r a i n s o n e i t h e r s i d e w o u l d b e d r y . T h i s m e a n t t h e d r a i n p a t t e r n h a d t o b e t i g h t e r t o i n c r e a s e t h e p r o b a b i l i t y o f t a p p i n g i n t o t h e s e p o c k e t s o f t r a p p e d w a t e r , a n d t h e t i g h t e r p a t t e r n a l s o m e a n t t h e o v e r a l l s l o p e was d r a i n e d m o r e q u i c k l y a f t e r a r a i n f a l l . 6 . 3 S U R F A C E RUNOFF T h e n a t u r a l g r o u n d s u r f a c e i s b l o c k y a n d m o s t p r e c i p i t a t i o n p e r c o l a t e s i n t o t h e r o c k m a s s . A s t r e a m c h a n n e l e x i s t s j u s t b e h i n d t h e w a l l , a n d t h i s i s a l l o w e d t o n a t u r a l l y d r a i n t h e a r e a . Where o p e r a t i o n s h a v e r e s l o p e d t h e c r e s t a r e a a l a y e r o f f i n e g r a i n e d m a t e r i a l e x i s t s , w h i c h h a s a l o w p e r m e a b i l i t y . D u r i n g h e a v y r a i n s u r f a c e r u n o f f i s a p r o b l e m . I n J u l y o f 1987 a r o a d a c t e d a s a s u r f a c e r u n o f f f l o w c h a n n e l , w h i c h d i r e c t e d w a t e r i n t o a 50 t e n s i o n c r a c k b e h i n d t h e c r e s t . V e r y q u i c k l y t h e w a t e r p r e s s u r e s b u i l t up t o t h e p o i n t w h e r e a m i n o r t o p p l i n g f a i l u r e o c c u r r e d . T o p r e v e n t f u t u r e o c c u r r e n c e s u n l i n e d d i t c h e s w e r e e x c a v a t e d , w h i c h d i r e c t e d w a t e r i n t o t h e c r e e k b e h i n d t h e c r e s t ; t h e c r a c k s w e r e c o v e r e d o n a r e g u l a r b a s i s , w h i c h b y S e p t e m b e r o f 1988 w e r e e v e r y w e e k . I d e a l l y t h e d i t c h e s a n d t h e c r e e k w o u l d h a v e b e e n l i n e d o r a c u l v e r t p l a c e d t o m i n i m i z e t h e e f f e c t s o f r e c h a r g e o n s t a b i l i t y . 6 . 4 DEWATERING THE V E R T I C A L L I M B D e w a t e r i n g t h e n o r t h w a l l i s d i f f i c u l t b e c a u s e t h e w a t e r t a b l e i s a l m o s t a t t h e b o t t o m o f t h e p i t w a l l . T h e o b j e c t i v e i s t o i n t e r s e c t p e r c h e d a n d t r a n s i e n t w a t e r t a b l e s a n d p r e v e n t h i g h w a t e r p r e s s u r e s f r o m d e v e l o p i n g i n t h e w a l l . T h e p o s s i b l e d e w a t e r i n g s y s t e m s i n c l u d e : i ) t h e sump m e t h o d , i i ) p i t p e r i m e t e r w e l l s , i i i ) i n - p i t w e l l p o i n t s y s t e m , i v ) h o r i z o n t a l d r a i n s , v ) a d r a i n a g e g a l l e r y w i t h r a d i a l d r a i n h o l e s a n d v i ) s e l f - d r a i n i n g w e l l s . A l l o f t h e a b o v e s y s t e m s , e x c e p t f o r h o r i z o n t a l d r a i n s a n d t h e d r a i n a g e g a l l e r y , w o u l d n o t w o r k d u e t o t h e v e r t i c a l g e o l o g i c s t r u c t u r e a n d b e c a u s e t h e m a i n o b j e c t i v e i s t o d r a i n t h e n o r t h w a l l n o t l o w e r t h e w a t e r t a b l e . 51 6 . 4 . 1 H O R I Z O N T A L DRAINS H o r i z o n t a l d r a i n a g e i s a v e r y e f f i c i e n t means o f d r a i n i n g a s l o p e t o i n c r e a s e s l o p e s t a b i l i t y . T h e d r a i n s , i f i n s t a l l e d p r o p e r l y , r e d u c e p o r e p r e s s u r e s , w h i c h i n c r e a s e s t h e s h e a r s t r e n g t h a l o n g d i s c o n t i n u i t i e s . T h e i n s t a l l a t i o n i s r e l a t i v e l y f a s t a n d i n e x p e n s i v e i f d o n e f r o m t h e p i t f l o o r . U n f o r t u n a t e l y , i n t h e V e r t i c a l L i m b , d r a i n a g e was i n s t a l l e d o n a l l t h e s a f e t y b e r m s a n d a c c e s s t o b e n c h f a c e s was a p r o b l e m b e c a u s e t h e s a f e t y b e r m w i d t h s w e r e s o n a r r o w . T h e s o l u t i o n was a t a n k d r i l l w h i c h was a b l e t o t r a v e l t h e s a f e t y b e r m s a n d d r i l l t h e h o l e s a t a n y a n g l e . T o i n s t a l l t h e d r a i n s 3 i n . d i a m e t e r h o l e s w e r e d r i l l e d , i n c l i n e d u p w a r d s a t a p p r o x i m a t e l y 1 0 ° . PVC p i p e s w i t h s l o t s o n t h e u p p e r h a l f w e r e p l a c e d i n t h e h o l e . F i g u r e 1 9 ( a ) shows a s l o p e b e i n g d e w a t e r e d u s i n g h o r i z o n t a l d r a i n s . 52 F i g u r e 19 S e c t i o n t h r o u g h a s l o p e s h o w i n g h o r i z o n t a l d r a i n s (a) a n d a d r a i n a g e g a l l e r y ( b ) . W a t e r t h a t d i d c o l l e c t i n t h e t r o u g h was d r a i n e d o u t o f t h e w a l l a n d t r i c k l e d o u t o n t o t h e b e n c h . A c o l l e c t i o n s y s t e m was n o t i n s t a l l e d a t t h e f a c e a n d a n y w a t e r c o l l e c t e d was i m m e d i a t e l y p u t b a c k i n t o t h e w a l l . T h i s was f e l t t o be b e t t e r t h e n a l l o w i n g a h i g h p r e s s u r e a r e a t o d e v e l o p i n b e h i n d t h e b e n c h f a c e . T h e a d v a n t a g e s a n d d i s a d v a n t a g e s o f h o r i z o n t a l d r a i n s a r e l i s t e d b e l o w : A d v a n t a g e s 1) I n e x p e n s i v e a n d s i m p l e t o i n s t a l l a n d m a i n t a i n . 2) W a l l s t a b i l i t y i s i n c r e a s e d b y t h e r e d u c t i o n o f p o r e p r e s s u r e s . 53 D i s a d v a n t a g e s 1) Does n o t l o w e r t h e w a t e r t a b l e b e l o w t h e p i t f l o o r . 2) I d e a l l y a w a t e r c o l l e c t i o n s y s t e m w o u l d b e i n s t a l l e d , w h i c h w o u l d p r e v e n t e q u i p m e n t f r o m t r a v e l l i n g a l o n g t h e s a f e t y b e r m s . 6 . 4 . 2 DRAINAGE G A L L E R Y T h i s s y s t e m c o n s i s t s o f a t u n n e l e x c a v a t e d a s h o r t d i s t a n c e b e h i n d a n d p a r a l l e l t o t h e p i t w a l l w i t h d r a i n h o l e s r a d i a t i n g i n t o t h e p i t w a l l ( F i g u r e 1 9 ( b ) ) . T h i s w o u l d h a v e w o r k e d w e l l i n t h e V e r t i c a l L i m b . I t w o u l d h a v e l o w e r e d t h e w a t e r t a b l e , i n c r e a s e d t h e s t a b i l i t y o f t h e w a l l when t h e c o a l was b e i n g s u b b e d , a n d d r a i n s d r i l l e d u p i n t o t h e p i t w a l l w o u l d h a v e r e d u c e d p o r e p r e s s u r e s . T h e d i s a d v a n t a g e s o f t h i s s y s t e m a r e t h e l a r g e c a p i t a l e x p e n d i t u r e s r e q u i r e d f o r i t s d e v e l o p m e n t a n d m a i n t e n a n c e , a n d t h e c o m p l e x i t y o f t h e s y s t e m i t s e l f . 6 . 4 . 3 DRAINAGE I N T H E V E R T I C A L LIMB A l t h o u g h d r a i n a g e was b e i n g c a l l e d f o r i n May o f 1 9 8 5 , when t h e p i t b o t t o m was a t 1690 m, a d r a i n a g e p r o g r a m was n o t b e g u n u n t i l j u s t b e f o r e t h e J u l y 1987 f a i l u r e , when t h e p i t b o t t o m was a t 163 0 m. D r a i n a g e a t t h i s t i m e c o n s i s t e d o f 20 m l o n g d r a i n h o l e s o n 30 m c e n t r e s , w i t h s l o t s a l l a r o u n d , w h i c h a l l o w e d c o l l e c t e d w a t e r t o e s c a p e f r o m t h e c a s i n g i n t o d r y b e d d i n g s u r f a c e s o r c r a c k s b e h i n d t h e f a c e . 54 T h e 169 0 b e n c h was c h o s e n b e c a u s e t h e m a t e r i a l o n t h e b e n c h e s a b o v e i s U p p e r G a t e s a n d H u l c r o s s , w h i c h d u e t o t h e b e n t o n i t i c c l a y l a y e r s a n d s h a l e s c o u l d t r a p p o c k e t s o f w a t e r a n d c a u s e a f a i l u r e . T h e M i d d l e G a t e s h a s a h i g h e r h y d r a u l i c c o n d u c t i v i t y , d u e t o t h e s a n d s t o n e , s o d r a i n a g e h e r e was n o t c o n s i d e r e d q u i t e a s c r u c i a l . A s s u m i n g movement was n o t o c c u r r i n g b e l o w t h e 1690 m b e n c h , a s i n s t a l l a t i o n m u s t b e g i n a t t h e b a s e o f t h e u n s t a b l e a r e a , a d d i n g t h e i n i t i a l r o w o f h o l e s o n t h i s b e n c h was c o n s i d e r e d c o r r e c t . D r a i n s s h o u l d a l s o h a v e b e e n p l a c e d o n t h e 1720 a n d 1750 b e n c h e s . W a t e r a c c u m u l a t e d i n a c r a c k a n d c a u s e d t h e f a i l u r e o f t h e 1750 b e n c h , w h i c h may h a v e b e e n p r e v e n t e d i f d r a i n a g e h a d b e e n i n s t a l l e d . I d e a l l y d r a i n a g e w o u l d h a v e b e e n i n s t a l l e d a s e a c h b e n c h was r e m o v e d . H a v i n g made t h e d e c i s i o n t o i n s t a l l d r a i n s when t h e p i t was a t 163 0 m, w o r k s h o u l d h a v e b e g u n a t t h e p i t b o t t o m r e g a r d l e s s o f t h e r o c k t y p e , b e c a u s e t h e l o w e r p a r t o f t h e w a l l was i n d e e d m o v i n g . T h e 163 0 m b e n c h r e c e i v e d n o d r a i n a g e a n d d u r i n g t h e w i n t e r o f 1 9 8 7 / 8 8 d r a i n s 20 m l o n g w e r e i n s t a l l e d o n t h e 1 6 4 0 , 1 6 6 0 , 1690 a n d 1720 b e n c h e s . D u r i n g J u l y a n d A u g u s t o f 1988 more f i l l - i n d r a i n s w i t h l e n g t h s v a r y i n g f r o m 3 0 t o 50 m w e r e i n s t a l l e d o n t h e 1 6 4 0 , 1660 a n d 1690 b e n c h e s (See t h e p i t s t a t u s map i n t h e b a c k p o u c h f o r t h e l o c a t i o n s o f a l l t h e d r a i n s ) . F o r t h e 40 m h i g h w a l l d r a i n a g e was a d d e d a s s o o n a s p o s s i b l e a f t e r e x c a v a t i o n a n d t o f a c i l i t a t e t h e l o w e r i n g o f 55 t h e w a t e r t a b l e a n d t o r e d u c e a n y g r o u n d w a t e r p r e s s u r e s . D r a i n s w e r e i n s t a l l e d o n t h e 162 0 a n d 1610 b e n c h e s a n d d r a i n a g e was p l a n n e d f o r t h e 1600 b e n c h . T h e h o l e s w e r e d r i l l e d , i n c l i n e d u p w a r d s a t a n a n g l e o f 1 0 ° o n 15 m c e n t r e s , w i t h t h e p r o v i s i o n t h a t i f a n y d r a i n s p r o d u c e d w a t e r a d d i t i o n a l d r a i n s w o u l d b e i n s t a l l e d . T h e d r a i n s g e n e r a l l y 15 m i n l e n g t h , w i t h e v e r y f o u r t h o n e a t 30 m, w e r e i n s t a l l e d a t e l e v a t i o n s o f 1621 m a n d 1611 m; t h e d e s i g n a l s o c a l l e d f o r d r a i n s a t 1601 m. T h e i n s t a l l e d s w e l l e x b o l t s a l l o w e d some e x t r a d r a i n a g e . 6 . 5 E F F E C T OF GROUNDWATER ON WALL S T A B I L I T Y G r o u n d w a t e r h a s t h e e f f e c t o f d e s t a b i l i z i n g a s l o p e b y s e v e r a l m e c h a n i s m s . R e d u c t i o n o f s h e a r s t r e n g t h d u e t o i n c r e a s i n g p o r e p r e s s u r e s i s t h e p r i m a r y o n e . T h e f o l l o w i n g e q u a t i o n shows t h e r e l a t i o n s h i p b e t w e e n s h e a r s t r e n g t h a n d p o r e p r e s s u r e : S = C + (CT-U) T a n <t> W h e r e S = S h e a r S t r e n g t h (N/m 2 ) C = C o h e s i o n (N/m 2 ) a = T o t a l n o r m a l s t r e s s (N/m 2 ) u = P o r e p r e s s u r e (N/m 2 ) <j> = F r i c t i o n a n g l e 56 I n c r e a s i n g t h e p o r e p r e s s u r e h a s t h e e f f e c t o f r e d u c i n g t h e n o r m a l e f f e c t i v e s t r e s s a c t i n g on a s u r f a c e , a n d t h i s i n t u r n d e c r e a s e s t h e s h e a r s t r e n g t h . W a t e r i n a t e n s i o n c r a c k g e n e r a t e s a l a r g e d e s t a b i l i z i n g f o r c e e q u a l i n m a g n i t u d e t o t h e a v e r a g e h y d r o s t a t i c p r e s s u r e m u l t i p l i e d b y t h e s u b m e r g e d a r e a o f t h e d i s c o n t i n u i t y . F o r t h i n c r a c k s a s m a l l amount o f s u r f a c e r u n o f f c a n g e n e r a t e v e r y h i g h f o r c e s . T h e d e s t a b i l i z i n g f o r c e i s g i v e n i n t h e f o l l o w i n g e q u a t i o n : F = i • 8 • H 2 • L Where F = D e s t a b i l i z i n g f o r c e (N) X = S p e c i f i c w e i g h t (N/m 3 ) H = H e i g h t o f w a t e r i n t h e c r a c k (m) L = L e n g t h ( a s s u m e d t o b e lm) S e e p a g e f o r c e s , w h i c h c a n d e s t a b i l i z e a s l o p e , o c c u r when w a t e r f l o w s t h r o u g h a p o r o u s m e d i u m , a n d e x e r t s a f o r c e , i n t h e d i r e c t i o n o f f l o w , o n t h e s o i l g r a i n s . T h e m a g n i t u d e o f t h e s e e p a g e f o r c e i s g i v e n b y t h e f o l l o w i n g e q u a t i o n : F = K - i - L - A W h e r e F = S e e p a g e f o r c e (N) Y = S p e c i f i c w e i g h t (N/m 3 ) i = H y d r a u l i c g r a d i e n t L = L e n g t h o f f l o w p a t h (m) A = C r o s s s e c t i o n a l a r e a o f f a i l u r e wedge 57 T h r o u g h t h e a c t i o n o f f r e e z e t h a w s m a l l b l o c k s may r a v e l o f f t h e b e n c h f a c e , w h i c h may d e s t a b i l i z e a l a r g e r b l o c k a n d r e s u l t i n a m i n o r f a i l u r e . T h i s i s n o t c o n s i d e r e d a m a j o r p r o b l e m . H y d r o d y n a m i c s h o c k c a n d e s t a b i l i z e a w a l l a n d c a u s e f a i l u r e when a b l a s t i s d e t o n a t e d b e l o w t h e w a t e r t a b l e . S h o c k w a v e s f r o m t h e b l a s t e x t e n d o u t w a r d a g r e a t e r d i s t a n c e a n d m a i n t a i n g r e a t e r v e l o c i t y when w a t e r i s e n c o u n t e r e d . T h e r e s u l t i s r o c k i s b r o k e n i n b e h i n d t h e f i n a l w a l l . 58 B L A S T I N G 7 . 1 B L A S T I N G AND I T S E F F E C T ON WALL S T A B I L I T Y T h e b l a s t i n g e n g i n e e r ' s t a s k i s a d i f f i c u l t o n e . T h e muck m u s t b e b r o k e n up s m a l l e n o u g h s o t h e s h o v e l s c a n w o r k e f f i c i e n t l y a n d s o t h a t w e a r a n d t e a r o n t r u c k s a n d s h o v e l s i s k e p t t o a m i n i m u m , b u t a t t h e same t i m e t h e p i t w a l l m u s t b e l e f t i n a s t a b l e c o n d i t i o n . When u n c o n t r o l l e d o r p o o r b l a s t i n g p r a c t i c e s a r e u s e d t h i s r e s u l t s i n r o u g h u n e v e n c o n t o u r s , o v e r b r e a k , o v e r h a n g s , e x c e s s i v e s h a t t e r i n g a n d e x t e n s i v e c r a c k s i n t h e s l o p e . T h i s damage i n c r e a s e s t h e amount o f s c a l i n g , t h e q u a n t i t y o f w a s t e r o c k t h a t h a s t o b e r e m o v e d a n d d e c r e a s e s s a f e t y b e r m w i d t h . E x c e s s i v e b l a s t s h o c k w a v e s a n d h i g h g a s p r e s s u r e s n e a r t h e f i n a l w a l l may a l s o r e s u l t i n c o n s i d e r a b l e l o s s o f c o h e s i o n a n d l o o s e n i n g o f t h e r o c k a l o n g f a u l t s , j o i n t s a n d b e d d i n g j o i n t s . New f r a c t u r e s c a n a l s o d e v e l o p . When t h i s o c c u r s b e h i n d t h e c r e s t i n f i l t r a t i o n o f s u r f a c e w a t e r i s made e a s i e r a n d t h i s may l e a d t o h i g h w a t e r p r e s s u r e s a n d u n n e c e s s a r y f r o s t a c t i o n . T h e u s e o f c o n t r o l l e d b l a s t i n g h a s t h e b e n e f i t o f c r e a t i n g a m o r e s t a b l e a n d u s u a l l y a n o v e r a l l s t e e p e r s l o p e . T h e c o s t o f c o n t r o l l e d b l a s t i n g i s h i g h e r , 10 -3 0% m o r e t h a n n o r m a l b l a s t i n g ( P i t e a u , 1979) a n d m o r e p i t s u p e r v i s i o n i s n e e d e d , b u t i n c r e a s e d s a f e t y a n d e f f i c i e n c y i s w o r t h t h e e x p e n d i t u r e . 59 7 . 2 B L A S T I N G PARAMETERS AND T H E I R E F F E C T ON PERFORMANCE When a n e x p l o s i v e i s d e t o n a t e d i t g e n e r a t e s g a s e s u n d e r v e r y h i g h p r e s s u r e , w h i c h a r e c o n f i n e d b y t h e r o c k m a s s , a n d t r a n s f e r l a r g e a m o u n t s o f e n e r g y i n t o t h e r o c k . T h e e n e r g y i s t r a n s p o r t e d r a d i a l l y away f r o m t h e b l a s t b y p r i m a r y , s e c o n d a r y a n d R a l e i g h s e i s m i c w a v e s . A s t h e wave moves t h r o u g h t h e r o c k i t e x e r t s a f o r c e o n s m a l l p a r t i c l e s w h i c h a r e d i s p l a c e d . T h e t y p e a n d s t r e n g t h o f t h e p a s s i n g wave f r o n t d e t e r m i n e s t h e l e v e l o f s t r a i n a n d p e a k p a r t i c l e v e l o c i t y . T o b r e a k t h e r o c k t h e maximum e l a s t i c s t r a i n m u s t b e e x c e e d e d . T h e a p p r o x i m a t e p e a k p a r t i c l e v e l o c i t y r e q u i r e d f o r t h e o n s e t o f r o c k b r e a k a g e i s a b o u t 63 c m / s i n a v e r a g e s t r e n g t h r o c k , i . e . , p e a k p a r t i c l e v e l o c i t i e s , a s h o r t d i s t a n c e b e h i n d t h e f i n a l row o f h o l e s , s h o u l d b e l e s s t h a n 63 c m / s t o k e e p damage t o t h e f i n a l p i t w a l l a t a m i n i m u m . E x p a n s i o n o f t h e g a s e s i n t o c r a c k s c a u s e d b y t h e p a s s i n g t e n s i l e wave f r o n t c a u s e s m o s t o f t h e d i s p l a c e m e n t o f t h e r o c k m a s s . T h e d i f f e r e n t i a l p r e s s u r e s e x e r t v e r y h i g h f o r c e s o n t h e b l o c k s o f r o c k a n d p u s h t h e m a p a r t a n d o u t w a r d t o w a r d t h e f r e e f a c e . I f t h e g a s e s a r e a b l e t o p r e m a t u r e l y e s c a p e , b e c a u s e t h e y a r e i n s u f f i c i e n t l y c o n f i n e d , t h e r e s u l t may b e c r a t e r i n g a n d f l y r o c k . H i g h p r e s s u r e d g a s e s p e n e t r a t i n g i n b e h i n d t h e f i n a l w a l l w i l l c a u s e d e g r a d a t i o n , a n d s t e p s s h o u l d b e t a k e n t o r e d u c e t h e 60 q u a n t i t y o f g a s g e t t i n g i n t o t h e f i n a l w a l l . F i g u r e 20 shows t h e m e c h a n i c s o f a b l a s t . 7 / tensi le wave '** / / / I I I F i g u r e 20 M e c h a n i c s o f a b l a s t ( S p e r l i n g , 1 9 8 5 ) . 1 . D e t o n a t i o n - h i g h p r e s s u r e g a s c r e a t e d . 2 . P wave h a s a d e q u a t e e n e r g y t o f r a c t u r e r o c k i n c o m p r e s s i o n f o r 4 d i a m . 3 . P wave r e f l e c t e d f r o m f r e e f a c e , f o r m s t e n s i l e wave p a r a l l e l t o f a c e . 4 . T e n s i l e wave f o r m s c r a c k s s i n c e t e n s i l e s t r e n g t h o f r o c k l o w . 5 . G a s e s e x p a n d i n t o t e n s i l e c r a c k s , h e a v e muck ( i l l u s t r a t e d o n p r e v i o u s r o w ) . 6 . New f r e e f a c e c r e a t e d ( i l l u s t r a t e d o n p r e v i o u s b u f f e r row) . T h e f o l l o w i n g p a r a m e t e r s c a n b e a d j u s t e d t o g e t t h e o p t i m u m b l a s t i n g p e r f o r m a n c e . 1) P o w d e r F a c t o r / S p e c i f i c C h a r g e (mass o f e x p l o s i v e u s e d / m a s s o f r o c k b r o k e n ) - T h e r a t i o s h o u l d b e a s l o w a s p o s s i b l e w h i l e m a i n t a i n i n g a d e q u a t e f r a g m e n t a t i o n . 2) B l a s t h o l e D i a m e t e r - L a r g e d i a m e t e r h o l e s a r e more e c o n o m i c a l (Hoek & B r a y , 1 9 8 1 ) , b u t f o r l i n e h o l e s n e x t t o t h e f i n a l w a l l t h i s c a n c a u s e e x c e s s i v e 61 f r a c t u r i n g , w h i c h s m a l l d i a m e t e r h o l e s w o u l d r e d u c e . 3) E x p l o s i v e C h a r g e p e r H o l e - T h i s s h o u l d b e o p t i m i s e d t o g i v e t h e b e s t p o s s i b l e f r a g m e n t a t i o n a n d d i g g i n g c o n d i t i o n s f o r t h e l o w e s t p o w d e r f a c t o r . 4) E f f e c t i v e H o l e S p a c i n g - S p a c i n g i s d i c t a t e d b y p o w d e r f a c t o r , c h a r g e p e r h o l e a n d g e o l o g y . 5) E f f e c t i v e B u r d e n ( d i s t a n c e b e t w e e n rows) - T h e d i s t a n c e s h o u l d b e l a r g e e n o u g h t o a l l o w f o r a d e q u a t e c o n f i n e m e n t , b u t s m a l l e n o u g h t o p r e v e n t a c h o k e d b l a s t . 6) F i r i n g O r d e r - F o r t h e v a r i o u s b l a s t i n g t e c h n i q u e s t h i s w i l l c h a n g e , b u t e v e r y h o l e s h o u l d d e t o n a t e a d j a c e n t t o a f r e e f a c e . 7) D e l a y s - S h o u l d b e l o n g e n o u g h t o p r e v e n t t h e r e i n f o r c e m e n t o f i n d i v i d u a l w a v e f r o n t s , a n d g i v e t h e r o c k i n f r o n t t i m e t o m o v e . T h e e x c e p t i o n i s l i n e h o l e s , w h i c h s h o u l d h a v e e a c h h o l e , n e a r t h e f i n a l w a l l , d e l a y e d . 8) Power o f E x p l o s i v e s - Low s t r e n g t h e x p l o s i v e s s h o u l d b e u s e d i n d e t o n a t i o n o f l i n e h o l e s i n c u s h i o n a n d p r e s h e a r b l a s t s . 9) S u b - d r i l l D e p t h - T h i s s h o u l d b e a s s h a l l o w a s p o s s i b l e , b u t a l s o p r o v i d e a d e q u a t e f r a g m e n t a t i o n . N e a r t h e f i n a l w a l l s u b - d r i l l i n g s h o u l d b e r e d u c e d a n d e v e n e l i m i n a t e d t o p r e v e n t d e g r a d a t i o n t o t h e t o e a n d c r e s t . 62 10) S t e m m i n g - I f n o t e n o u g h i s u s e d g a s e s c a n p r e m a t u r e l y -e s c a p e , w h i c h w i l l c a u s e f l y r o c k , a i r b l a s t a n d r e d u c e t h e e f f e c t i v e n e s s o f t h e b l a s t . T o o much w i l l c a u s e t h e r o c k a b o v e t h e t o p l o a d t o h a v e p o o r f r a g m e n t a t i o n . 7.3 I N I T I A L B L A S T I N G P R A C T I C E S I N THE V E R T I C A L L I M B B u f f e r o r c u s h i o n b l a s t i n g h a s a t r i m p a t t e r n n e x t t o t h e w a l l c o n s i s t i n g o f a row o f l i n e h o l e s a n d two r o w s o f b u f f e r h o l e s . T h i s p a t t e r n i s d e t o n a t e d a f t e r t h e m a i n b l a s t a n d p e e l s t h e r o c k away f r o m t h e f i n a l w a l l . T o k e e p damage t o t h e f i n a l w a l l a t a m i n i m u m t h e c h a r g e p e r h o l e i s r e d u c e d . T h e p o w d e r f a c t o r h a s t o b e m a i n t a i n e d t o g e t c o r r e c t f r a g m e n t a t i o n , s o t h e s p a c i n g o f t h e t r i m p a t t e r n i s s m a l l e r t h a n t h e p r o d u c t i o n p a t t e r n . T o p r e v e n t t h e r e i n f o r c e m e n t o f s e v e r a l l o w e n e r g y w a v e s d e l a y s a r e u s e d b e t w e e n e a c h l i n e h o l e , e a c h b u f f e r h o l e a n d e a c h r o w . T h e d e t o n a t i o n p a t t e r n commences w i t h t h e s e c o n d b u f f e r r o w f o l l o w e d b y t h e f i r s t b u f f e r row a n d f i n a l l y t h e l i n e h o l e s . T h e a d v a n t a g e s o f t h i s t r i m p a t t e r n a r e t h e h o l e s p a c i n g i s l a r g e r , w h i c h r e d u c e s d r i l l i n g c o s t s , b e t t e r h o l e a l i g n m e n t w i t h l a r g e d i a m e t e r h o l e s a n d u s i n g t h e r e s u l t s f r o m t h e f i r s t s h o t p e r m i t s a d j u s t m e n t o f l o a d s i f n e c e s s a r y . T h e d i s a d v a n t a g e s a r e : s o m e t i m e s o v e r b r e a k f r o m t h e f i r s t s h o t may r e m o v e t h e b e r m t o b e c u s h i o n e d b l a s t e d , w h i c h w o u l d r e q u i r e l o a d a d j u s t m e n t s f o r s e v e r a l h o l e s i n t h e t r i m 63 p a t t e r n a n d m a t e r i a l f r o m t h e p r i m a r y b l a s t h a s t o b e r e m o v e d f i r s t b e f o r e f i r i n g t h e c u s h i o n b l a s t . T h e 1750 b e n c h u s e d t h e c u s h i o n b l a s t i n g t e c h n i q u e a n d t h e r e s u l t was a c c e p t a b l e . T h e 1735 b e n c h b l a s t d e s i g n r e s u l t e d i n t h e c r e s t o f t h e 1750 b e n c h f a i l i n g b y t o p p l i n g ( F i g u r e 2 1 ( a ) shows t h e b l a s t i n g p a t t e r n i n c r o s s - s e c t i o n ) . To p r e v e n t f u r t h e r b l a s t - i n d u c e d f a i l u r e s t h e b l a s t d e s i g n was c h a n g e d . F e w e r h o l e s w e r e d r i l l e d , s t o p p e d 0 . 5 m s h o r t o f t h e p r o p o s e d b e n c h f a c e a n d l o a d e d l i g h t e r . H o l e s d r i l l e d o v e r t h e f i n a l b e n c h g r a d e w e r e n o t d r i l l e d b e l o w g r a d e a n d t h e b l a s t p a t t e r n was l a i d o u t i n s u c h a m a n n e r t h a t b l a s t h o l e s s p a n n e d p r o p o s e d b e n c h c r e s t s ( F i g u r e 2 1 ( b ) ) . T h e r e s u l t s w e r e s t i l l p o o r a n d i n t h e n o s e a r e a b l a s t - i n d u c e d t o p p l i n g f a i l u r e s o f t h e 1 7 2 0 , 1735 a n d 1750 b e n c h c r e s t s o c c u r r e d . 64 ft, led bu • ^ \ \T50 g/osfhele. drilled 4o qrvde. N T S . a) <.cberra-Hc sectiott of blast design used -for sxcai/afiai o-f 1TZ5 Bench. L) Schema-be of proposed blast des/jn -for l~7ZO Ber>ch Blowholes dri/bJ -ho o-Sm obcMc grodex^y Blast holes drilled So yrade / 7 3 T 6hsrholc£> -h Sfon bench Ce£t I120 \ \ F i g u r e 21 B l a s t p a t t e r n f o r t h e 1735 b e n c h i n c r o s s - s e c t i o n (a) a n d t h e p r o p o s e d b l a s t d e s i g n f o r t h e 172 0 b e n c h (b) ( H a w l e y , 1 9 8 4 ) . 65 7 . 4 CURRENT B L A S T I N G P R A C T I C E S I N THE V E R T I C A L L I M B P r e s h e a r o r p r e - s p l i t b l a s t i n g c o n s i s t s o f a s i n g l e row o f c l o s e l y s p a c e d h o l e s d r i l l e d a l o n g t h e f i n a l d i g l i n e , a n d two rows o f b u f f e r h o l e s . T h e h o l e d i a m e t e r f o r t h e l i n e h o l e s a r e s u p p o s e d t o b e s m a l l e r t h a n t h e d i a m e t e r u s e d f o r c u s h i o n b l a s t i n g , a n d t h e r e f o r e , t h e s p a c i n g i s t i g h t e r . T h e m a i n d i f f e r e n c e b e t w e e n c u s h i o n a n d p r e s h e a r b l a s t i n g i s t h a t t h e p r e s h e a r h o l e s a r e f i r e d a h e a d o f t h e p r o d u c t i o n h o l e s . W i t h p r e s h e a r when two c h a r g e s a r e f i r e d s i m u l t a n e o u s l y i n a d j a c e n t h o l e s t h e c o l l i s i o n o f t h e s h o c k w a v e s g e n e r a t e s a t e n s i l e wave i n t h e web . T h i s c a u s e s c r a c k i n g b u t d o e s n o t p r e v e n t s e i s m i c w a v e s f r o m r e a c h i n g b e h i n d t h e f i n a l d i g l i n e . H i g h p r e s s u r e d g a s e s a r e v e n t e d w h i c h h e l p s s o l v e t h e p r o b l e m o f g a s e n t e r i n g p r e e x i s t i n g j o i n t s b e h i n d t h e f i n a l w a l l a n d o p e n i n g t h e m u p . O t h e r a d v a n t a g e s i n c l u d e t h e r e m o v a l o f a l e s s e r amount o f m a t e r i a l d u e t o o v e r b r e a k , i n c r e a s e d s t a b i l i t y o f t h e f i n a l w a l l , l e s s s c a l i n g r e q u i r e d , a n d s t e e p e r s l o p e s may b e p o s s i b l e . H o w e v e r , t h e d i s a d v a n t a g e s a r e : i n c r e a s e d d r i l l i n g c o s t s a s s m a l l e r d i a m e t e r h o l e s , c r u c i a l f o r g e t t i n g a g o o d p r e s h e a r p l a n e , a r e u s e d a n d d r i l l h o l e a l i g n m e n t i s l e s s a c c u r a t e . T h i s t e c h n i q u e d o e s n o t w o r k w e l l i n w e l l j o i n t e d h a r d r o c k , p a r t i c u l a r l y w h e r e t h e j o i n t s a r e o p e n a n d i n c l i n e d t o t h e p r e s h e a r l i n e (Hoek a n d B r a y , 1 9 8 1 ) . 66 T h e b e n c h e s f r o m 1705 m down w e r e b l a s t e d u s i n g p r e s h e a r b l a s t i n g t e c h n i q u e s . T h e 0 . 3 1 m d i a m e t e r p r o d u c t i o n h o l e s , a r e d r i l l e d 2 m b e l o w t h e n e x t b e n c h l e v e l , h a v e a p o w d e r f a c t o r o f a p p r o x i m a t e l y 0 . 2 2 k g / t o n n e , h o l e s p a c i n g s r a n g i n g f r o m 8x8 t o 9 . 5 x 9 . 5 m a n d c h a r g e s a r e d e c k e d . P r o d u c t i o n h o l e s l o c a t e d o v e r t h e n e x t s a f e t y b e r m a r e d r i l l e d t o g r a d e a n d a r e l o a d e d w i t h l e s s e x p l o s i v e . T h e p r e s h e a r h o l e s a r e . 3 1 m i n d i a m e t e r , a r e d r i l l e d t o g r a d e , a r e 4 m a p a r t a n d t h e c h a r g e s c o n s i s t o f a 43 k g t o e l o a d a n d a 43 k g s o n o t u b e l o a d . T h e t i g h t e r p r e s h e a r s p a c i n g a l l o w s t h e t e n s i l e w a v e s t o f o r m i n t h e web , t h i s c r e a t e s t h e c r a c k a l l o w i n g g a s e s t o e s c a p e . T h e s o n o t u b e i s u s e d t o d e c o u p l e t h e c h a r g e r e d u c i n g damage t o t h e r o c k m a s s . T h e p r e s h e a r h o l e s i n some i n s t a n c e s w e r e d e t o n a t e d w e l l i n a d v a n c e o f t h e n e x t b l a s t , w h i c h i s a c c e p t a b l e i f t h e w a t e r t a b l e i s b e l o w t h e n e x t b e n c h . O t h e r w i s e a h y d r o d y n a m i c s h o c k wave w i l l f o r m d u r i n g t h e n e x t b l a s t c a u s i n g damage t o t h e w a l l . F o r t h e p r e s h e a r e d b e n c h e s down t o 1 6 3 0 , 50 m / s d e l a y s w e r e u s e d , b u t f o r t h e 1620 a n d 1610 b e n c h e s 100 m / s a n d 75 m / s d e l a y s w e r e u s e d r e s p e c t i v e l y . I n t h e s t u d y a r e a t h e w a l l s a b o v e 1705 w e r e v e r y b l o c k y a n d r a g g e d , a n d t h e s l o p e s u b j e c t t o m i n o r f a i l u r e s a n d r o c k f a l l s . F r o m 1705 down t o 1690 t h e b e n c h f a c e i s c l e a n , v e r t i c a l a n d p l a n a r , d u e t o t h e c h a n g e i n g e o l o g y . J u s t b e h i n d t h e 1690 m b e n c h f a c e i s t h e c o n t a c t b e t w e e n t h e U p p e r a n d L o w e r G a t e s . T h e U p p e r G a t e s i s p o o r q u a l i t y 67 m a t e r i a l a n d b e h a v e s l i k e H u l c r o s s , a n d t h i s g a v e t h e p o o r f i n a l b e n c h f a c e s . T h e m a t e r i a l m a k i n g up t h e 1690 b e n c h f a c e i s c o m p e t e n t s a n d s t o n e , a p p r o x i m a t e l y 2 m t h i c k , w h i c h p r o d u c e d a g o o d f i n a l w a l l . T h e c o n d i t i o n o f t h e b e n c h c r e s t s , f a c e s a n d t o e s b e l o w 1690 m a r e g e n e r a l l y i n g o o d s h a p e , b u t t h e r e a p p e a r s t o h a v e b e e n f r a c t u r i n g o f t h e r o c k b e h i n d t h e f i n a l d i g l i n e . T h e r e s u l t i s t h e 1640 s a f e t y b e r m i s n o t w i d e e n o u g h f o r e q u i p m e n t a n d c a n n o t b e c l e a r e d o f t a l u s . G a s e s g e n e r a t e d d u r i n g d e t o n a t i o n p e n e t r a t e d p a s t t h e p r e s h e a r p l a n e a n d i n t o o p e n j o i n t s b e h i n d t h e f i n a l d i g l i n e . T h i s s u g g e s t s t h e p r e s h e a r l i n e i s n o t w o r k i n g a s e f f i c i e n t l y a s h o p e d . T h e s h o v e l o p e r a t o r e x c a v a t e s t o t h e f i n a l d i g l i n e , b u t t h e u n s t a b l e w a l l w i l l n o t s t a n d u p , d i g g i n g c o n t i n u e s u n t i l m a t e r i a l s t o p s f a l l i n g i n t o t h e p i t . T h e f i n a l o u t c o m e i s a s m a l l e r t h a n d e s i g n e d s a f e t y b e r m w i d t h . 7 . 5 P O S S I B L E IMPROVEMENTS AND RECOMMENDATIONS Q u i n t e t t e ' s u s e o f c o n t r o l l e d b l a s t i n g h a s h e l p e d t o r e d u c e damage t o t h e f i n a l w a l l s . B l a s t damage w o u l d h a v e b e e n f a r g r e a t e r i f p r o d u c t i o n b l a s t s w e r e u s e d t h r o u g h o u t . H o w e v e r , f u r t h e r r e s e a r c h n e e d s t o b e d o n e t o d e t e r m i n e t h e b e s t p a t t e r n s a n d b l a s t i n g t e c h n i q u e s f o r t h e d i f f e r e n t r o c k u n i t s , H u l c r o s s , U p p e r G a t e s a n d L o w e r G a t e s . P o s s i b l e i m p r o v e m e n t s a r e : s m a l l e r d i a m e t e r h o l e s f o r t h e p r e s h e a r l i n e h o l e s , c l o s e r s p a c i n g a n d r e d u c t i o n o f e x p l o s i v e c h a r g e 68 i n t h e p r e s h e a r h o l e s a n d i n s t a l l i n g d e l a y s b e t w e e n b u f f e r h o l e s . 7 . 5 . 1 I N C L I N E D S M A L L DIAMETER HOLES S m a l l e r d i a m e t e r i n c l i n e d h o l e s w i l l m a x i m i z e t h e h e i g h t o f t h e e x p l o s i v e c o l u m n , e v e n o u t t h e e x p l o s i v e e n e r g y a n d e n h a n c e s l o p e s t a b i l i t y . T h e i n c l i n e d h o l e s p a r a l l e l t o t h e f i n a l b e n c h f a c e w i l l r e s u l t i n l e s s damage t o t h e t o e o f t h e b e n c h . C u r r e n t l y t h e p r e s h e a r l i n e p r o m o t e s a v e r t i c a l f a c e , b e c a u s e t h e h o l e s a r e d r i l l e d v e r t i c a l , a n d t h e t o e i s t h e r e f o r e s e v e r e l y f r a c t u r e d b y t h e t o e l o a d o f 43 k g o f ANFO a n d b y g a s e s f r o m t h e p r o d u c t i o n a n d b u f f e r h o l e s . 7 . 5 . 2 R E D U C T I O N OF E X P L O S I V E CHARGE A t p r e s e n t 86 k g o f ANFO a r e p u t i n e a c h p r e s h e a r h o l e . T h e U . S . B u r e a u o f M i n e s E m p i r i c a l F o r m u l a t h a t r e l a t e s p e a k p a r t i c l e v e l o c i t y , r a d i a l d i s t a n c e f r o m d e t o n a t i o n a n d w e i g h t o f e x p l o s i v e c h a r g e p e r d e l a y i s shown g r a p h i c a l l y i n F i g u r e 2 2 . 69 F i g u r e 22 P l o t o f p a r t i c l e v e l o c i t i e s i n d u c e d a t g i v e n d i s t a n c e s b y p a r t i c u l a r c h a r g e s f o r a v e r a g e s t r e n g t h r o c k (Hoek a n d B r a y , 1 9 8 1 ) . 70 T h e e q u a t i o n u s e d t o d e r i v e t h e s e l i n e s i s : V=K(R /VW) Q E q . 7 . 5 . 2 . 1 V=Peak p a r t i c l e v e l o c i t y ( i n / s ) R = R a d i a l d i s t a n c e f r o m b l a s t ( f t ) W=Weight o f e x p l o s i v e p e r d e l a y ( l b ) K = C o n s t a n t , f u n c t i o n o f r o c k mass B = C o n s t a n t , f u n c t i o n o f r o c k mass T h e v a l u e s o f K a n d B , w h i c h a r e b a s e d o n t h e e l a s t i c p r o p e r t i e s o f t h e r o c k m a s s , t y p i c a l l y r a n g e f r o m 26 t o 260 f o r K , a n d B i s a p p r o x i m a t e l y - 1 . 6 (Hoek a n d B r a y , 1 9 8 1 ) . U s i n g t h e w e i g h t o f e x p l o s i v e i n a p r e s h e a r h o l e a n d t h a t r o c k b r e a k s a t p e a k p a r t i c l e v e l o c i t i e s o f 25 i n / s t h e r a d i a l d i s t a n c e f r o m t h e h o l e a t w h i c h r o c k w i l l b e damaged c a n b e c a l c u l a t e d . T a b l e 4 V a l u e s u s e i n e q u a t i o n 7 . 5 . 2 . 1 a n d t h e r e s u l t i n g r a d i a l d i s t a n c e s f r o m t h e b l a s t a t w h i c h r o c k w i l l b r e a k . C o n d i t i o n K 6 W ( l b ) R ( f t ) W o r s t 260 - 1 . 7 190 5 4 . 7 B e s t 26 - 1 . 6 190 1 4 . 1 M o s t L i k e l y 200 - 1 . 6 190 5 0 . 6 T h e a b o v e r e s u l t s i n d i c a t e t h a t p r e s e n t p r e s h e a r b l a s t s a r e d a m a g i n g r o c k a s much a s 5 4 . 7 f e e t ( 1 6 . 6 m) b e h i n d t h e f i n a l d i g l i n e , b u t t h e c h a r g e i s d e c o u p l e d , w h i c h r e d u c e s t h e d i s t a n c e . H o w e v e r , t o r e d u c e damage t o t h e f i n a l w a l l 71 t h e l o a d i n t h e p r e s h e a r h o l e s s h o u l d b e r e d u c e d . U s i n g F i g u r e 22 a n d t h e m o s t l i k e l y v a l u e s o f K a n d S , t h e c h a r g e p e r d e l a y c a n b e d e t e r m i n e d . T h e c h a r g e c a n n o t b e r e d u c e d t o o much o t h e r w i s e a l l t h e e x p l o s i v e w i l l b e a t t h e b o t t o m o f t h e h o l e . T h e b e s t s o l u t i o n w o u l d b e t o r e d u c e t h e h o l e s p a c i n g t o 3 m, r e d u c e t h e l o a d t o 45 t o 55 k g a n d e l i m i n a t e t h e t o e l o a d . T h i s g i v e s a p o w d e r f a c t o r o f 0 . 1 5 k g / t o n n e , w h i c h i s c o n s i s t e n t w i t h p r e v i o u s b l a s t s , a n d t h e r a d i a l d i s t a n c e w o u l d b e l e s s t h a n 5 m, when d e c o u p l e d c h a r g e s a r e u s e d . 7 . 5 . 3 D E L A Y S BETWEEN B U F F E R HOLES B u f f e r h o l e s a r e c u r r e n t l y d e t o n a t e d a s t h e e n d h o l e s o f t h e p r o d u c t i o n l i n e . T h e r e c o m m e n d a t i o n i s t o u s e d e l a y s so t h a t e a c h b u f f e r h o l e i s d e t o n a t e d o n e h o l e a t a t i m e , a n d t o u s e two r o w s o f b u f f e r s . P r e v i o u s b l a s t r e c o r d s s u g g e s t t h a t p r e s e n t b l a s t p a t t e r n s w o u l d c a u s e b r e a k a g e b e h i n d t h e p r e s h e a r p l a n e . 72 8. A R T I F I C I A L SUPPORT T h e i n i t i a l m i n e p l a n d i d n o t c a l l f o r a r t i f i c i a l s u p p o r t i n t h e V e r t i c a l L i m b . W i t h t h e d e c i s i o n t o h a v e a q u a d r u p l e b e n c h f r o m 1640 m t o 1600 m, t o make r o o m f o r t h e d r a g l i n e i n c r e a s i n g t h e s t r e n g t h o f t h e l o w e r w a l l was r e q u i r e d . T h e p r i n c i p a l mode o f f a i l u r e i s t o p p l i n g , b u t t h e s u p p o r t r e q u i r e m e n t s w e r e b a s e d o n t h e c a s e o f a n o v e r h u n g o r d a y l i g h t e d s l a b r e s t i n g o n b e d d i n g . T h e r e s u l t a n t f o r c e s i n t h e t o e b l o c k f o r t o p p l i n g f a i l u r e s a r e v e r y h i g h , s o t h e r o c k b o l t s p l a c e d a t t h e b a s e o f t h e w a l l w i l l p r o v i d e a d d i t i o n a l s t r e n g t h a n d p r o l o n g t h e f a i l u r e . A l t h o u g h , t h i s w o u l d o n l y r e a l l y a p p l y f o r b e n c h s c a l e f a i l u r e s . O t h e r ways o f d e a l i n g w i t h t o p p l i n g f a i l u r e s a r e t o i n c r e a s e d r a i n a g e , r e s l o p e t h e c r e s t a r e a a n d d e c r e a s e s l o p e a n g l e , p u t i n r o c k b o l t s i n t h e c r e s t a r e a t o i n c r e a s e s l a b t h i c k n e s s , k e e p w a t e r f r o m i n f i l t r a t i n g t e n s i o n c r a c k s o r a d d a t o e b u t t r e s s . R e s l o p i n g o f t h e c r e s t a r e a a n d f i l l i n g i n c r a c k s t o p r e v e n t i n f i l t r a t i o n was a n o n g o i n g c o n c e r n a n d o p e r a t i o n s b e g a n t o i n s t a l l d r a i n a g e i n t h e f a l l - w i n t e r o f 1 9 8 7 . I n s t a l l i n g s h o r t r o c k b o l t s a t t h e c r e s t o n l y w o r k s f o r s m a l l f a i l u r e s , a n d b e n c h s c a l e f a i l u r e s . L o n g e r b o l t s a r e r e q u i r e d t o s t a b i l i z e m u l t i -b e n c h s l o p e s . A d d i n g a b u t t r e s s a t t h e t o e d e f e a t s t h e p u r p o s e o f h a v i n g t h e q u a d r u p l e b e n c h . F l a t t e n i n g t h e o v e r a l l s l o p e a n g l e was n o t c o n s i d e r e d a s t h e p i t was a l r e a d y t o o n a r r o w . 73 T h e r o c k b o l t s w e r e i n s t a l l e d a s s o o n a s p o s s i b l e a f t e r e x c a v a t i o n , b u t d r a i n a g e was c o n s i d e r e d m o r e i m p o r t a n t a n d i n s t a l l e d f i r s t . T h i s m e a n t r o c k b o l t i n g c r e w s d i d n o t g a i n a c c e s s u n t i l a l l t h e m a t e r i a l was e x c a v a t e d a n d t h e w a l l s s c a l e d . T h i s t i m e l a g a l l o w s some s t r e s s r e l i e f t o t a k e p l a c e , b u t w h e t h e r p e a k s h e a r s t r e n g t h was p r e s e r v e d i s u n k n o w n . I f t h e p e a k s h e a r s t r e n g t h i s r e d u c e d t h e n t h e s u p p o r t s y s t e m s m u s t a p p l y a d d i t i o n a l s t r e n g t h t o e n s u r e t h e s l o p e i s s t r e n g t h e n e d . 8 . 1 SUPPORT SYSTEMS USED I N THE V E R T I C A L L I M B T h e s u p p o r t s y s t e m i n s t a l l e d was n e v e r m e a n t t o s t o p t h e t o p p l i n g f a i l u r e o r s t o p t h e w a l l f r o m d e g r a d i n g . I n s t e a d t h e s y s t e m was i n s t a l l e d t o a d d e n o u g h a d d i t i o n a l s u p p o r t t o a l l o w m i n i n g o f t h e c o a l b e f o r e d e g r a d a t i o n became t o o s e r i o u s . T i m i n g was v e r y i m p o r t a n t . T h e w a l l t o b e s u p p o r t e d was 40 m i n h e i g h t w i t h a n a v e r a g e b e n c h f a c e a n g l e o f 6 5 ° . B e d d i n g d i p s v e r y c l o s e t o v e r t i c a l , d i p p i n g i n t o a n d o u t o f t h e w a l l . A 30 m h i g h w a l l was t o b e l e f t s t a n d i n g d u r i n g t h e summer o f 1988 , w h i c h p r o m p t e d t h e u s e o f two s u p p o r t s y s t e m s , t h e s w e l l e x a n d d y w i d a g . T h e s w e l l e x c o u l d h a v e b e e n u s e d s o l e l y b u t t o i n c r e a s e t h e f a c t o r o f s a f e t y d u r i n g t h e we t p e r i o d some o f t h e s w e l l e x b o l t s w e r e r e p l a c e d w i t h d y w i d a g b o l t s . 74 8 . 1 . 1 SWELLEX BOLTS T h e s w e l l e x b o l t s w e r e c h o s e n o v e r g r o u t e d d o w e l s o r r e s i n a n c h o r e d d o w e l s , b e c a u s e o f t h e d i f f i c u l t y o f i n s t a l l i n g t h e s e s y s t e m s d u r i n g t h e c o l d w i n t e r m o n t h s . S w e l l e x b o l t s a c t a s p a r t i a l d r a i n s , a n d l o n g e r l e n g t h s c a n a l s o b e i n s t a l l e d . T h e t h e o r y b e h i n d t h e s w e l l e x i s i t s h o u l d b e i n s t a l l e d a s s o o n a s t h e p i t w a l l i s e x p o s e d , s o t h e d o w e l s c a n b e s t r e s s e d b y t h e s t r e s s r e l i e f o c c u r r i n g i n t h e r o c k m a s s . U n f o r t u n a t e l y s w e l l e x b o l t s w e r e p u t i n a f t e r d r a i n a g e a n d s c a l i n g , s o t h e r e was a d e l a y o f u p t o a c o u p l e o f weeks f r o m t h e t i m e t h e w a l l s w e r e e x c a v a t e d . T h i s means t h e b o l t o n l y became s t r e s s e d when movement o c c u r r e d a l o n g a d i s c o n t i n u i t y , a n d a n y s t r e n g t h t h a t may h a v e e x i s t e d , i n t h e d i s c o n t i n u i t y was now r e d u c e d . T h e s w e l l e x b o l t s u s e d h a v e t h e f o l l o w i n g c h a r a c t e r i s t i c s : - S t r e n g t h o f a p p r o x i m a t e l y 25000 l b s - D r i l l h o l e d i a m e t e r o f 38 mm - L e n g t h o f 6 . 1 m - 6x6 i n . f a c e p l a t e - c a n b e c o n n e c t e d t o g e t h e r t o o b t a i n g r e a t e r l e n g t h s i f r e q u i r e d T h e h o l e s , d r i l l e d b y a t a n k d r i l l , w e r e b l o w n o u t b e f o r e t h e b o l t s w e r e i n s t a l l e d . A f a c e p l a t e was u s e d , w h i c h p r o v i d e s a r e a c t i o n f o r c e a g a i n s t t h e p i t w a l l . O n c e t h e f a c e p l a t e a n d b o l t w e r e i n s t a l l e d a n i n f l a t i o n pump was u s e d t o e x p a n d t h e b o l t a g a i n s t t h e s i d e s o f t h e d r i l l h o l e . T h i s s y s t e m i s s i m p l e t o i n s t a l l . 75 8 . 1 . 2 DYWIDAG D y w i d a g b o l t s w e r e n o t i n t e n d e d i n i t i a l l y b u t w i t h t h e c h a n g e i n t h e m i n i n g s c h e d u l e , w h i c h l e f t a 30 m h i g h w a l l e x p o s e d d u r i n g t h e summer m o n t h s o f 1 9 8 8 , i n s t a l l a t i o n o f t h e s e h i g h c a p a c i t y a n c h o r s was c o n s i d e r e d n e c e s s a r y d u e t o h i g h e r r o c k s t r e s s e s . T h e s e b o l t s w e r e a n c h o r e d u s i n g g r o u t , a n d t e n s i o n e d t o g i v e a d d i t i o n a l s t r e n g t h t o t h e w a l l . T h e p r i m a r y a i m o f t h e s e a n c h o r s was t o r e d u c e t h e d i l a t i o n o f t h e r o c k mass a n d p r o v i d e a d d i t i o n a l p i n n i n g o f t h e l o w e r p a r t o f t h e w a l l . A l l t h e a n c h o r s w e r e t o h a v e b e e n i n s t a l l e d b e f o r e f r e e z e u p b u t d u e t o t h e t o p p l i n g f a i l u r e i n S e p t e m b e r i n s t a l l a t i o n e x t e n d e d i n t o t h e w i n t e r m o n t h s . L i k e t h e s w e l l e x b o l t s , i n s t a l l a t i o n o c c u r r e d a c o n s i d e r a b l e t i m e a f t e r e x c a v a t i o n was c o m p l e t e d . T h e r e s u l t o f t h i s d e l a y i s a n y s t r e n g t h l o s t d u e t o movement a l o n g d i s c o n t i n u i t i e s h a s t o b e made u p f o r b y t h e t e n s i o n p u t i n t o t h e b o l t . T h e r o c k b o l t i s now n o t a s e f f e c t i v e a s t h e d e s i g n c a l l e d f o r . T h e D y w i d a g T h r e a d B a r s u s e d h a v e t h e f o l l o w i n g c h a r a c t e r i s t i c s : - 150 k s i g r a d e s t e e l . - U l t i m a t e s t r e n g t h o f a p p r o x i m a t e l y 187 k i p s , w h i c h p r o v i d e s a maximum w o r k i n g l o a d o f 112 k i p s a t 60% o f u l t i m a t e . - B o l t d i a m e t e r o f 1 . 2 5 i n . - L e n g t h o f 40 f t . - 1 i n c h t h i c k s t e e l p l a t e , 12 i n c h e s s q u a r e w i t h wedge w a s h e r s t o a c c o m m o d a t e v a r i a t i o n s i n r o c k p r o f i l e a n d a k e y h o l e t o a c c o m m o d a t e a g r o u t l i n e . - S p a c e r s t o k e e p t h e b o l t away f r o m t h e w a l l o f t h e d r i l l h o l e . 76 C e m e n t g r o u t a n c h o r s w e r e c h o s e n b e c a u s e t h e y a r e e a s i e r t o i n s t a l l a n d h a v e a s h o r t e r l e a r n i n g c u r v e t h a n t h e p o l y e s t e r r e s i n a n c h o r . T h e c h a r a c t e r i s t i c s o f t h e c e m e n t g r o u t a r e : - 0 . 4 t o 0 . 4 5 w a t e r / c e m e n t r a t i o b y w e i g h t - S h o u l d b e a p r e m i x e d n o n - s h r i n k t y p e , f o r f a s t e r s e t . - H a v e a min imum c o m p r e s s i o n s t r e n g t h o f 2 000 p s i a f t e r 3 d a y s a n d 4500 p s i a f t e r 28 d a y s . T o p r e v e n t t h e g r o u t f r o m r u n n i n g o u t t h e h o l e t h e h o l e was i n c l i n e d d o w n w a r d s . T h e p r o c e d u r e f o r i n s t a l l a t i o n c o n s i s t e d o f b l o w i n g o u t t h e h o l e a n d g r o u t i n g t h e l o w e r 16 f e e t . T h e b a r , w i t h t h e s p a c e r s , was t h e n l o w e r e d down t h e h o l e i n t o t h e g r o u t , a n o t h e r s p a c e r o n t h e e n d o f t h e b a r was u s e d t o a l l o w a c o m p l e t e a n n u l u s o f g r o u t t o f o r m a r o u n d t h e b a r ( F i g u r e 2 3 ) . A p p r o x i m a t e l y t h r e e d a y s l a t e r , when t h e g r o u t h a d s e t , t h e b a r was p r o o f l o a d e d t o 758 MPa b y j a c k i n g w i t h a h y d r a u l i c j a c k a n d t h e n b l e d b a c k t o 552 M P a . T o p r e v e n t s t r e s s c o r r o s i o n , w h i c h c o u l d r e s u l t i n f a i l u r e o f t h e b a r i n t h e f o r m o f a p r o j e c t i l e f l y i n g o u t o f t h e h o l e , t h e f r e e a n c h o r l e n g t h was g r o u t e d . T h i s g r o u t e d l e n g t h o f b a r a l s o h e l p s t o t r a n s f e r s t r e s s e s i n t o t h e r o c k m a s s . Some p r e c a u t i o n s w i t h t h e g r o u t i n g r e q u i r e t h e s e c o n d a r y g r o u t i n g t o e x t e n d t o t h e a n c h o r g r o u t , o t h e r w i s e s t r e s s a n d r u s t c o r r o s i o n w i l l o c c u r ; g r o u t o l d e r t h a n one h o u r s h o u l d n o t b e u s e d a n d s h o u l d b e f r e e o f l u m p s a n d u n d i s p e r s e d c e m e n t . T h e s e c o n d a r y g r o u t h a s t h e same w a t e r / c e m e n t r a t i o a s t h e a n c h o r g r o u t , a n d t h e g r o u t s h o u l d 77 b e m i x e d i n a c o n t i n u o u s s h e a r e r t y p e m i x e r t o t h e m a n u f a c t u r e r 1 s r e c o m m e n d a t i o n s . F i g u r e 23 S k e t c h s h o w i n g d e s i g n o f h i g h c a p a c i t y a n c h o r s ( C a v e r s , 1 9 8 8 ( c ) ) . 78 8 . 2 ROCK BOLT P A T T E R N T h e s w e l l e x b o l t p a t t e r n was d e t e r m i n e d b y t r a n s l a t i o n a l a n a l y s i s a n a l y z i n g t h e c a s e o f a n o v e r h u n g o r d a y l i g h t e d s l a b r e s t i n g o n b e d d i n g a n d s u p p o r t e d w i t h r o c k b o l t s ( F i g u r e 2 4 ) . T e c h n i c a l l y t h e s w e l l e x b o l t s w i l l n o t b e a p p l y i n g a n y s t r e s s t o t h e r o c k m a s s , a s t h e b o l t s a r e n o t t e n s i o n e d b u t , c o n s i d e r i n g t h e r o u g h b e d d i n g s u r f a c e s w h i c h e x i s t , a n y movement w i l l r e s u l t i n d i l a t i o n a n d a p p l y a t e n s i l e f o r c e a c r o s s t h e b o u n d i n g d i s c o n t i n u i t y . I n s t a l l a t i o n o f t h e d o w e l s w i t h i n a s h o r t d i s t a n c e o f t h e p i t b o t t o m a n d a t a n u p w a r d i n c l i n a t i o n w i l l a l s o h e l p t e n s i o n t h e d o w e l s . 79 T H I C K N E S S O F B L O C K S H E A R S T R E N G T H A L O N G 5EPDINQ <0) T E N S I O N I N ANCHOR ( T ) B L O C K W E I G H T ( V ) D I R E C T I O N O F I N C I P I E N T MOVEMENT F i g u r e 24 T r a n s l a t i o n a l movement a l o n g a v e r t i c a l j o i n t ( C a v e r s , 1 9 8 7 ( D ) ) . T h e a n a l y s i s was d o n e u s i n g t h e f o l l o w i n g e q u a t i o n : F a c t o r o f S a f e t y (F) = (W + T C o s e) T a n $ W - T S i n e W = W e i g h t o f b l o c k ( l b s ) T = T e n s i o n i n t h e b o l t ( l b s ) e = A n g l e t h e b o l t m a k e s t o t h e h o r i z o n t a l $ = S h e a r s t r e n g t h a l o n g b e d d i n g s u r f a c e T h e p a r a m e t e r s u s e d w e r e a f r i c t i o n a n g l e o f 3 5 ° a n d a b l o c k t h i c k n e s s o f 1 m, w h i c h a r e f e l t t o b e o n t h e c o n s e r v a t i v e s i d e . A t a f a c t o r o f s a f e t y o f 1 t h e b o l t 80 f o r c e r e q u i r e d i s 25000 l b s o r 110 KN a p p l i e d a t a n a n g l e o f 15 -2 0 ° o v e r a n a r e a o f 15 m 2 . T h i s s a f e t y f a c t o r was u s e d b e c a u s e o f i n t e n s e m o n i t o r i n g d u r i n g e x c a v a t i o n a n d i f a p r o b l e m a r e a i s e x p o s e d a d d i t i o n a l b o l t s c a n b e a d d e d . F o r b e n c h e s 162 0 m a n d 163 0 m t h e 6 .2 m l o n g s w e l l e x b o l t s w e r e i n s t a l l e d o n 3 m c e n t r e s a t e l e v a t i o n s 1 6 3 6 , 1 6 3 2 , 1626 a n d 1621 m. F o r t h e 1610 m b e n c h s w e l l e x b o l t s w e r e i n s t a l l e d a t t h e 1616 m l e v e l o n 3 m c e n t r e s a n d 6 m c e n t r e s o n t h e 1611 m l e v e l . A l s o o n t h e 1611 m l e v e l 1 2 . 2 m l o n g d y w i d a g t h r e a d b a r s w e r e i n s t a l l e d o n 6 m c e n t r e s . T h e s e b o l t s p r o v i d e a p p r o x i m a t e l y s i x t i m e s m o r e s u p p o r t t h a n t h e s w e l l e x a n d i n c r e a s e t h e f a c t o r o f s a f e t y t o g r e a t e r t h a n 1. T h e b o l t i n g p a t t e r n f o r t h e 1600 b e n c h c a l l e d f o r o n l y one row o f b o l t s a t 1601 m, a n d was t o c o n s i s t o f d y w i d a g s o n 12 m c e n t r e s a n d s w e l l e x o n 3 m c e n t r e s ( F i g u r e 2 5 ) . 81 NOTE: PATTERN AND ANGLES ARE THE SAME ON BOTH WALLS. SOUTH WALL NORTH WALL - 1640 M - 1620 M - 1600 M I F i g u r e 25 S c h e m a t i c c r o s s - s e c t i o n s h o w i n g b o l t i n g p a t t e r n f o r n o r t h a n d s o u t h w a l l s ( C a v e r s , 1 9 8 7 ( D ) ) . 82 9 . MONITORING M o n i t o r i n g p r o g r a m s c a n b e d i v i d e d i n t o t h r e e s t a g e s : t h e d e t e c t i o n o f t h e i n s t a b i l i t y , u n d e r s t a n d i n g t h e m e c h a n i c s o f f a i l u r e a n d m i n e a n d m o n i t o r . F o r e a c h d i f f e r e n t s t a g e t h e m o n i t o r i n g t e c h n i q u e s , e q u i p m e n t a n d p e r s o n n e l r e q u i r e m e n t s w i l l v a r y . T h e m a i n o b j e c t i v e o f m o n i t o r i n g p r o g r a m s i s t h e same , b u t t h e i n f o r m a t i o n n e e d e d w i l l c h a n g e d e p e n d i n g o n t h e t y p e o f f a i l u r e i . e . , m o n i t o r i n g p r o g r a m s a r e s i t e s p e c i f i c , a n d , a s a t Q u i n t e t t e , t h e m o n i t o r i n g p r o g r a m i s d e v e l o p e d a s i n s t a b i l i t y w o r s e n s . T h e i n s p e c t i o n , c l o s u r e a n d r e o p e n i n g p r o c e d u r e s f o r t h e M a r m o t V e r t i c a l L i m b a r e p r e s e n t e d i n A p p e n d i x B . 9 . 1 L E V E L S OF MONITORING USED I N THE V E R T I C A L L I M B 9 . 1 . 1 PRIMARY T h e o b j e c t i v e a t t h i s s t a g e was t o i d e n t i f y a m a j o r f a i l u r e a s s o o n a s movement o c c u r r e d . T h e e a r l i e r t h e p o t e n t i a l f a i l u r e was d e t e c t e d t h e b e t t e r t h e c h a n c e s t h a t r e m e d i a l m e a s u r e s c o u l d p r e v e n t a f a i l u r e f r o m o c c u r r i n g . I f t h e e a r l y s i g n s o f f a i l u r e w e r e n o t d e t e c t e d , a n d t h e r e f o r e , t h e a r e a was n o t m o n i t o r e d , workmen a n d e q u i p m e n t w e r e a t r i s k . A n o t h e r r e a s o n f o r g e t t i n g t o a f a i l u r e a s s o o n a s movement o c c u r r e d was t h a t , v e r y q u i c k l y , t h e s h e a r s t r e n g t h a l o n g t h e f a i l u r e p l a n e d e c r e a s e s f r o m p e a k t o 83 r e s i d u a l a n d e x t r a a r t i f i c i a l s u p p o r t t h e n h a s t o b e i n s t a l l e d u n n e c e s s a r i l y . O b s e r v a t i o n was t h e m o s t p r a c t i c a l way o f d e t e c t i n g m o v e m e n t . F r o m e x p e r i e n c e i t h a d b e e n f o u n d t h a t l a r g e s l i d e s t y p i c a l l y h a v e c r a c k s t h a t o p e n up l o n g b e f o r e t h e f a i l u r e o c c u r s u n l e s s t r i g g e r e d b y l a r g e s e i s m i c e v e n t s , s u c h a s , e a r t h q u a k e s . I t w o u l d b e a d i f f i c u l t t a c k f o r one i n d i v i d u a l t o l o o k f o r new c r a c k s i n a l l t h e p i t s . T h i s r e q u i r e s t h e c o o p e r a t i o n o f a l l p i t e m p l o y e e s . D u r i n g a n i n s p e c t i o n o f b e n c h c r e s t s a n d w a l l s t h e G e o t e c h n i c a l E n g i n e e r l o o k e d f o r c r a c k s , e v i d e n c e o f i n c r e a s e d r a v e l l i n g , f r e s h r o c k f a l l s a n d a b n o r m a l s e e p a g e f r o m t h e w a l l s . A s m i n i n g a c t i v i t y d e s c e n d e d t h e u p p e r b e n c h e s b e c o m e m o r e i s o l a t e d a n d l e s s f r e q u e n t l y t r a v e l l e d , s o t h e s e b e n c h e s w e r e i n s p e c t e d b y t h e G e o t e c h n i c a l E n g i n e e r . T h e f r e q u e n c y o f i n s p e c t i o n s was a f u n c t i o n o f c l i m a t e a n d p i t a c t i v i t i e s . D u r i n g s p r i n g r u n o f f a n d t i m e s o f h e a v y r a i n f a l l t h i s was a s o f t e n a s o n c e a week a n d o n a m o n t h l y b a s i s d u r i n g t h e r e s t o f t h e y e a r . I f t h e s t r u c t u r a l g e o l o g y was o r i e n t e d i n s u c h a way t h a t f a i l u r e c o u l d o c c u r t h e n m e a s u r e s o t h e r t h e n p e r s o n a l o b s e r v a t i o n may b e u s e d . EDM ( e l e c t r o n i c d i s t a n c e m e a s u r i n g ) p r i s m s w e r e p u t o n t h e c r e s t o f t h e p i t a n d a l o n g a b e n c h m i d - w a y up t h e w a l l i n t h e a r e a o f c o n c e r n . T h i s a p p r o a c h was e f f e c t i v e b u t r e q u i r e d a c c u r a t e s u r v e y i n g a n d a t e c h n i c i a n t o do t h e s u r v e y s . A t t i m e s w e a t h e r was a 84 p r o b l e m , s o v i s u a l o b s e r v a t i o n s w e r e s t i l l t h e m o s t r e l i a b l e means o f d e t e c t i n g a n u n s t a b l e a r e a . A t t h i s s t a g e g r o u n d w a t e r p r e s s u r e s w e r e a l s o m o n i t o r e d . T h e i n f o r m a t i o n g a t h e r e d was u s e d t o p r e d i c t t h e q u a n t i t i e s o f i n f l o w i n t o t h e p i t , d e t e r m i n e t h e m a g n i t u d e o f w a t e r p r e s s u r e s i n b e h i n d t h e w a l l a n d e v a l u a t e t h e e f f e c t i v e n e s s o f a n y d e w a t e r i n g p r o g r a m s . T h e p i e z o m e t e r s w e r e r e a d m o r e f r e q u e n t l y d u r i n g s p r i n g t h a w t o w a r n o f e x c e p t i o n a l l y h i g h w a t e r p r e s s u r e s , a n d w e r e r e a d p e r i o d i c a l l y d u r i n g t h e r e s t o f t h e y e a r t o d e t e r m i n e how t h e w a t e r t a b l e f l u c t u a t e d . 9 . 1 . 2 SECONDARY O n c e a n u n s t a b l e a r e a h a d b e e n i d e n t i f i e d i n f o r m a t i o n o n t h e t y p e o f f a i l u r e , t h e g e o m e t r y , t h e p r o b a b l e c a u s e , t h e a p p r o x i m a t e g r o u n d w a t e r p r e s s u r e s a c t i n g o n t h e f a i l u r e p l a n e a n d i n t h e s l i d e m a s s , a n d t h e r a t e a n d d i r e c t i o n o f movement was g a t h e r e d . U s i n g t h i s i n f o r m a t i o n i t was p o s s i b l e t o d e t e r m i n e w h e t h e r , w i t h f u r t h e r a c t i o n o r r e m e d i a l m e a s u r e s a m i n e a n d m o n i t o r p r o g r a m c o u l d b e a p p l i e d . I f t h e h i s t o r y o f movement r a t e s w e r e n o t known t h e n t h e a r e a was c l o s e d o f f u n t i l e n g i n e e r i n g p e r s o n n e l w e r e a b l e t o d e t e r m i n e w h e t h e r t h e a r e a o f i n s t a b i l i t y was s a f e a n d w h e t h e r t h e movement r a t e s w e r e g o i n g t o a c c e l e r a t e . 85 T h e s e c o n d a r y l e v e l o f m o n i t o r i n g b e g a n a s s o o n a s t h e f i r s t c r a c k was d i s c o v e r e d . A n i m m e d i a t e s u r v e y o f t h e a r e a was c o m p l e t e d t o l o c a t e i f o t h e r c r a c k s e x i s t e d , a n d t o l o o k f o r e v i d e n c e o f g r o u n d w a t e r s e e p a g e a n d g e o l o g i c s t r u c t u r e w h i c h may c o n t r o l t h e f a i l u r e . T o d e t e r m i n e t h e movement r a t e s a t e m p o r a r y e x t e n s o m e t e r was s e t u p o v e r t h e u p p e r m o s t c r a c k , c o n s i s t i n g o f a 1 m s p i k e p o u n d e d i n t o t h e r o c k o r a 25 cm l o n g r o c k b o l t a n c h o r e d o n e a c h s i d e o f t h e c r a c k ( F i g u r e 2 6 ) . T h e d i s t a n c e was m e a s u r e d a t t h e t i m e o f i n s t a l l a t i o n o r a s s o o n a s t h e g r o u t , a n c h o r i n g t h e b o l t , h a d c u r e d . R e a d i n g s w e r e t a k e n e v e r y 12 h o u r s i f t h e r a t e was g r e a t e r t h a n 1 c m / d a y , a n d f o r r a t e s o f l e s s t h e n 1 c m / d a y r e a d i n g s w e r e t a k e n f u r t h e r a p a r t t o g e t u s e f u l d a t a . T h e r e s u l t s w e r e p l o t t e d up d a i l y o n c u m u l a t i v e movement v s . t i m e g r a p h s a n d i n t e r p r e t e d b y t h e g e o t e c h n i c a l e n g i n e e r . 86 F i g u r e 26 T e n s i o n c r a c k d i s p l a c e m e n t m o n i t o r i n g t o o l ( S p e r l i n g , 1 9 8 5 ) . T o d e t e r m i n e t h e a r e a l e x t e n t o f t h e f a i l u r e a n d t h e movement d i r e c t i o n s EDM p r i s m s w e r e l o c a t e d o v e r a n d a r o u n d t h e a r e a o f i n s t a b i l i t y i n l i n e s g o i n g u p t h e s l o p e . F r o m t h e r e s u l t i n g movement v e c t o r s t h e t y p e o f f a i l u r e c o u l d b e d e t e r m i n e d a s i l l u s t r a t e d i n F i g u r e 2 7 . P i e z o m e t e r s w e r e i n s t a l l e d , a n d r e a d i n g s t a k e n t o d e t e r m i n e t h e w a t e r p r e s s u r e s i n t h e s l i d e a n d a c t i n g o n t h e f a i l u r e p l a n e . New p i e z o m e t e r s w e r e i n s t a l l e d a l o n g t h e c e n t r e l i n e o f t h e s l i d e , a n d d e e p e n o u g h t o b e l o c a t e d b e l o w t h e p r e d i c t e d f a i l u r e p l a n e . F r o m t h e a b o v e i n f o r m a t i o n t h e s i z e o f t h e s l i d e was a s c e r t a i n e d ; w h e t h e r a m i n e a n d m o n i t o r p r o g r a m was f e a s i b l e ; w h e t h e r s t a b i l i z a t i o n was p o s s i b l e a n d w h a t t h e r e c o m m e n d e d s t a b i l i z a t i o n m e t h o d s h o u l d b e . 87 I S O M E T R I C X - S E C T I O N FAILURE MODE DISPLACEMENT V E C T O R S 'A. WEDGE - REQUIRES TWO INTERSECTING PLANES - TENSION CRACK MAY DEVELOP - STABILITY FUNCTION OF WEDGE GEOMETRY, SHEAR STRENGTH AND GROUNDWATER PLANE - MOVEMENT ON ONE PLANE - REQUIRES LATERAL RELEASE SURFACES - PLANE PARALLEL TO FACE +/- 20o - MUST DAYLIGHT BLOCK - RARE IN HARD ROCK MINES - DRIVEN BY WATER PRESSURES IN TENSION CRACK - USUALLY REQUIRES LOW STRENGTH - BASAL PLANE, E.G. CLAY \ TOPPLING - REQUIRES STEEPLY DIPPING JOINTS - STABILITY FUNCTION OF GEOMETRY, SHEAR STRENGTH AND GROUNDWATER STEP - WILL OCCUR ONLY IN VOLCANICS - REQUIRES CLOSELY SPACED AND DISCONTINUOUS JOINTS - CONTOLS BERM FACE ANGLE - STABILITY LIKELY A FUNCTION OF TRIM BLASTING METHOD - y r \ *~" \ r CIRCULAR - REQUIRES UNIFORM WEAK MATERIAL - BACK SCARP HAS NEAR VERTICAL DISPLACEMENT - STABILITY FUNCTION OF GEOMETRY GROUNDWATER, SHEAR STRENGTH \ * BUCKLING - REQUIRES THINLY BEDDED STRATIGRAPHY DIPPING >A0 DEGREES - STABILITY FUNCTION OF STRUCTURE, GROUNDWATER, SHEAR STRENGTH, SLOPE HEIGHT UNLIKELY TO SPOT WITH HUBS F i g u r e 27 Common f a i l u r e modes i n o p e n p i t s , a n d t h e i r r e s u l t a n t v e c t o r o r i e n t a t i o n s ( S p e r l i n g , 1985) 88 9 . 1 . 3 MINE AND MONITOR E x p e r i e n c e h a s shown t h a t m i n i n g c a n c o n t i n u e u n d e r a n a r e a t h a t i s i n t h e p r o c e s s o f f a i l i n g i f t h e r i g h t s a f e g u a r d s a r e i n p l a c e . T h e l a s t l e v e l o f m o n i t o r i n g , m i n e a n d m o n i t o r , c o n s i s t e d o f t h e s e s a f e g u a r d s . T o u s e t h e m i n e a n d m o n i t o r m e t h o d e x c e p t i o n a l l y a c c u r a t e i n s t r u m e n t a t i o n i s n e e d e d t o a c q u i r e t h e movement r a t e s . T h i s i n s t r u m e n t a t i o n may i n c l u d e o n e o r more o f t h e f o l l o w i n g : E D M , s h e a r s t r i p s e x t e n s o m e t e r s , p o t e n t i o m e t e r s , i n c l i n o m e t e r s , p i c k e t l i n e s , t e l e m e t r y a n d p u l l e y m o n i t o r i n g s y s t e m s w i t h l i m i t s w i t c h e s . L a r g e f a i l u r e s g e n e r a l l y g i v e p l e n t y o f w a r n i n g . T h e p r i n c i p a l a i m o f m i n e a n d m o n i t o r i n g i s t o i d e n t i f y t h e w a r n i n g a n d e v a c u a t e t h e a r e a i n t i m e . T h e w a r n i n g comes i n t h e f o r m o f a n i n c r e a s e i n t h e movement r a t e s o f t h e u n s t a b l e r o c k m a s s , a n d i s d e t e c t e d b y t a k i n g r e a d i n g s o n a d a i l y b a s i s a n d p l o t t i n g them o n a c u m u l a t i v e movement v s . t i m e g r a p h . A s t h e c u r v e b e c o m e s s t e e p e r t h e movement r a t e s a c c e l e r a t e , a n d f a i l u r e w i l l o c c u r when t h e c u r v e i s a s y m p t o t i c t o t h e v e r t i c a l . T h e w a r n i n g comes when t h e s l o p e o f t h e c u r v e c h a n g e s a n d b e g i n s t o c l i m b s t e e p l y ( F i g u r e 2 8 ) . T h e movement r a t e a t w h i c h t h i s c h a n g e o c c u r s v a r i e s , b u t f o r s l i d e s e x c e e d i n g 1 0 0 , 0 0 0 m 3 a r a t e o f 7 . 5 c m / d a y c a n b e u s e d a s a g u i d e f o r when t o r e m o v e men a n d e q u i p m e n t . S m a l l s l i d e s a r e n o t s o p r e d i c t a b l e a n d c a n o c c u r c a t a s t r o p h i c a l l y . 89 CUMULATIVE NET MOVEMENT vs TIME STATION 172501 16-Jun 06-Jul 26-Jul 15-Aug 04-Sep 24-Sep TIME (DAYS) 1988 • HORIZONTAL MOVEMENT + VERTICAL MOVEMENT F i g u r e 28 P l o t o f c u m u l a t i v e movement v e r s u s t i m e . T h e s l o p e o f t h e c u r v e c h a n g e s a s m o v e m e n t s a c c e l e r a t e t o f a i l u r e . A t t h i s s t a g e o f m o n i t o r i n g , p i t p e r s o n n e l d i d m o r e t h a n l o o k f o r c r a c k s . T h e y l i v e d a n d w o r k e d w i t h t h e m o n i t o r i n g s y s t e m , a n d h a d t o u n d e r s t a n d t h e n a t u r e o f t h e f a i l u r e , t h e m o n i t o r i n g s y s t e m i n p l a c e a n d w h a t was r e q u i r e d i f a n a l a r m was r a i s e d . T h e d a t a c o l l e c t e d f r o m t h e m o n i t o r i n g e q u i p m e n t was p l o t t e d a n d i n t e r p r e t e d t o i n f o r m t h e p i t c r e w s o f t h e p r e s e n t c o n d i t i o n s . T h e two t y p e s o f i n s t r u m e n t a t i o n u s e d a t Q u i n t e t t e t o m o n i t o r t h e f a i l u r e w e r e t h e e x t e n s o m e t e r a n d E D M . T h e e x t e n s o m e t e r was n o t t h e p r i m a r y s y s t e m , b u t was u s e d when t h e w e a t h e r c o n d i t i o n s p r e v e n t e d a EDM s u r v e y b e i n g d o n e . T h e s y s t e m c o n s i s t e d o f a c c u r a t e l y m e a s u r i n g t h e d i s t a n c e b e t w e e n r e b a r o r s m a l l r o c k b o l t s a n c h o r e d o n e i t h e r s i d e o f a c r a c k o r s e r i e s o f c r a c k s . T h e e x t e n s o m e t e r h a d a s t e e l t a p e , w h i c h a p p l i e d t h e same p u l l i n g f o r c e o n e a c h o c c a s i o n a n d c o u l d b e r e a d t o a n a c c u r a c y o f one t e n t h o u s a n d t h o f a n i n c h . T h e b o r e h o l e s f o r t h e r e b a r a n d r o c k b o l t s w e r e d r i l l e d u s i n g a p o r t a b l e h a n d h e l d r o c k d r i l l p o w e r e d b y a c h a i n s a w e n g i n e . A n e x t e n s o m e t e r s t a t i o n was e s t a b l i s h e d q u i c k l y , a n d t h e r e a d i n g s w e r e e a s y t o t a k e a n d a n a l y z e . One p r o b l e m e n c o u n t e r e d was t h e t a p e b e i n g b l o w n a r o u n d i n t h e h i g h w i n d s m a k i n g a c c u r a t e r e a d i n g s h a r d e r t o t a k e . T h e e x t e n s o m e t e r s t a t i o n s w e r e o n l y r e a d b y e n g i n e e r i n g s t a f f , a n d a c c e s s t o s t a t i o n s was d i f f i c u l t . R e a d i n g s w e r e t a k e n p e r i o d i c a l l y d u r i n g t h e summer o f 1988 a n d o n a d a i l y b a s i s j u s t b e f o r e t h e f a i l u r e o c c u r r e d . I n s t a l l i n g a p u l l e y t y p e m o n i t o r i n g s y s t e m a s shown i n F i g u r e 29 w o u l d h a v e b e e n i d e a l , b e c a u s e i t i s s i m p l e , e f f e c t i v e a n d c a n u s u a l l y b e o b s e r v e d b y p i t p e r s o n n e l . U n f o r t u n a t e l y , i n t h e V e r t i c a l L i m b , t h e p i t i s s t e e p a n d n a r r o w a n d t h e w i n d i s n e a r l y a l w a y s b l o w i n g , s o a s i g n a l may n o t b e s e e n o r h e a r d . 91 A U T O M A T I C A U D I O V I S U A L F i g u r e 29 S u r f a c e e x t e n s o m e t e r t o m e a s u r e c r a c k o p e n i n g ( H a w l e y , P . M . e t a l . , 1 9 8 5 ) . T h e p r i n c i p a l m e t h o d f o r m o n i t o r i n g t h e f a i l u r e was t h e E D M . A S u r v e y E n g i n e e r was h i r e d t o i n c r e a s e t h e a c c u r a c y o f t h e s u r v e y i n g , b e c a u s e movements i n t h e o r d e r o f a few m i l l i m e t r e s w o u l d h a v e t o b e m e a s u r e d . P r i s m s w e r e l o c a t e d s e l e c t i v e l y o v e r t h e w a l l , a n d i n s t a l l e d o n b e n c h c r e s t s a n d a t t h e t o e o f t h e b e n c h f a c e s . P e r m a n e n t p i l l a r s w e r e b u i l t f o r t h e t r a n s i t t o r e d u c e v i b r a t i o n s f r o m t h e t r i p o d d u e t o t h e w i n d , a n d t o n e g a t e t h e e r r o r i n c u r r e d e a c h t i m e t h e t r a n s i t was s e t u p . Two f i x e d s t a t i o n s , w e l l b e h i n d t h e c r a c k s , w e r e l o c a t e d t o p r o v i d e a b a c k s i t e a n d t o a l l o w t h e l o c a t i o n o f t h e o t h e r t r a n s i t s t a t i o n s t o b e c a l c u l a t e d , a s 92 t h e y w e r e m o v i n g . T h e p i t s t a t u s map i n t h e j a c k e t shows t h e l o c a t i o n o f t h e f i x e d s t a t i o n s a n d t h e p e r m a n e n t p i l l a r s . T h e f r e q u e n c y o f EDM s u r v e y s a n d v i s u a l i n s p e c t i o n s v a r i e d w i t h t h e l a s t s e t o f r e a d i n g s . T a b l e 5 shows t h e s i x d i f f e r e n t s t a g e s a n d t h e i r r e s p e c t i v e t h r e s h o l d movement r a t e s . When t h e w e a t h e r p r e v e n t e d a s u r v e y f r o m b e i n g d o n e t h e movement r a t e s f r o m t h e e x t e n s o m e t e r s t a t i o n s w e r e u s e d . T h e s e r e a d i n g s h a d t o b e i n t e r p r e t e d c a r e f u l l y , b e c a u s e t h e w h o l e e x t e n s o m e t e r s e t up was l o c a t e d o n t h e f a i l u r e m a s s . T h e r e f o r e t h e movements b e i n g r e c o r d e d w e r e b e t w e e n i n d i v i d u a l b l o c k s w i t h i n t h e s l i d e . T h e m i n e a n d m o n i t o r m e t h o d h a s b e e n u s e d s u c c e s s f u l l y a t o t h e r s i t e s . T h e C h u q u i c a m a t a C o p p e r M i n e i n C h i l e ( K e n n e d y , 1969) i s one e x a m p l e , A f t o n m i n e s i n B . C . i s a n o t h e r ( R e i d & S t e w a r t , 1 9 8 6 ) , a n d t h e t o p p l i n g f a i l u r e a t S t e e p R o c k M i n e s L t d i n O n t a r i o i s a t h i r d ( B r a w n e r e t . a l , 1 9 7 5 ) . A t S t e e p R o c k a t o p p l i n g f a i l u r e was d e t e c t e d a b o v e a n a c t i v e p a r t o f t h e m i n e , w h i c h was s o o n t o b e m i n e d o u t . I n s t e a d o f a b a n d o n i n g t h e o r e a m i n e a n d m o n i t o r p r o g r a m was i n i t i a t e d t o e x t r a c t t h e o r e s a f e l y . I n s t r u m e n t a t i o n u s e d i n c l u d e d t r i a n g u l a t i o n , EDM, w i r e e x t e n s o m e t e r s w i t h l i m i t s w i t c h e s , c r a c k s e p a r a t i o n c a l l i p e r s a n d a s e i s m i c u n i t . T h e m o s t u s e f u l p i e c e s o f e q u i p m e n t w e r e t h e w i r e e x t e n s o m e t e r s a n d t h e E D M . 93 T a b l e 5 T h e s i x d i f f e r e n t s t a g e s o f m o n i t o r i n g a n d t h e i r r e s p e c t i v e t h r e s h o l d movement r a t e s . THRESHOLD HORIZONTAL MOVEMENT RATES STAGE STATUS ran/day DURATION ACTION COMMENTS 1 Stable <1.5 3 week avg. Monitor to be read again within one week Stable or s l i g h t 1 movement 2 Active Toppling 1.5-4 3 week avg. Monitor to be read again within one week Inspection by Geotechnical Engineer or q u a l i f i e d designate twice a week Recognized on - going toppling 3 Caution >4 3 week avg. Monitor to be read again within 72 hours Inspection by Area Foreman or General Foreman every 24 hours Rapid toppling movement J u l y 27/87 minor f a i l u r e was triggered by a half hour heavy r a i n f a l l event during t h i s stage of movement 4 Ea r l y A l e r t 15 1 day Monitor a l l points on fol l o w i n g day Threshold reached eight times since August/86 5 A l e r t 15 2 days Take second set of reading on a l l points the same day ie . check readings V i s u a l l y inspect benches and walls . N o t i f y Geotechnical Con-s u l t a n t D. Cavers of Hardy BBT. Reached once since Aug/86 by monitor immediately above the Ju l y 27, 1987 minor f a i l u r e 6 Evalua-t i o n 25 3 days Read instrumentation twice per day in problem area More d e t a i l e d evaluation may be required V i s u a l l y inspect every 4 hours Has not occurred since the monitor system established September, 1985 94 T h e m i n e a n d m o n i t o r p r o g r a m w o r k e d v e r y w e l l a t S t e e p R o c k . A s w e l l a s t h e m o n i t o r i n g e q u i p m e n t a u n i o n member was o n s i t e 24 h o u r s a d a y l o o k i n g f o r a n y r a v e l l i n g o r o t h e r s i g n o f i m p e n d i n g f a i l u r e . A l l movement r a t e s w e r e p l o t t e d a n d d i s p l a y e d i n t h e m i n e d r y , s o t h a t a l l p e r s o n n e l w e r e a w a r e o f t h e s l i d e s s t a t u s . 9 . 2 PREVIOUS MONITORING NETWORKS 9 . 2 . 1 SURVEY EQUIPMENT P r i o r t o M a r c h 1988 a K e r n E l e l e c t r o n i c t h e o d o l i t e i n c o n j u n c t i o n w i t h a DM503 d i s t a n c e m e t e r was u s e d f o r a l l o b s e r v a t i o n s . D a t a c o l l e c t e d i n t h e f i e l d was s t o r e d i n a d a t a c o l l e c t o r a n d was s u b s e q u e n t l y i n t e r f a c e d w i t h a c o m p u t e r f o r p e r m a n e n t r e c o r d a n d a n a l y s i s . T h e t h e o d o l i t e a n d d i s t a n c e m e t e r u s e d w o u l d v a r y f r o m s u r v e y t o s u r v e y a s t h e y w e r e u s e d i n t h e p i t o n a r e g u l a r b a s i s . 9 . 2 . 2 METHODOLOGY AND ACCURACY A l l s u r v e y m e a s u r e m e n t s t a k e n f o r t h e n o r t h w a l l w e r e made f r o m one s t a t i o n , 5 0 6 , l o c a t e d o n t h e s o u t h w a l l . B e f o r e a n y r e a d i n g s w e r e t a k e n t h e i n s t r u m e n t was c a r e f u l l y l e v e l l e d a n d c a l i b r a t e d t o e n s u r e maximum a c c u r a c y . T h e t e m p e r a t u r e a n d p r e s s u r e w e r e m e a s u r e d a n d t h e a p p r o x i m a t e s c a l e c o r r e c t i o n a p p l i e d t o a l l d i s t a n c e s m e a s u r e d . A s t a t i o n 4 000 m away was u s e d a s a b a c k s i g h t a n d d i s t a n c e a n d a n g l e w e r e m e a s u r e d t o a s t a t i o n c o n s i d e r e d s t a b l e t o c h e c k 95 t h e i n s t r u m e n t s e t u p . T h e n f o r e a c h p r i s m f i v e r e a d i n g s w e r e t a k e n i n t h e d i r e c t mode a n d f i v e i n t h e r e v e r s e mode . T h e mean o f t h e t e n r e a d i n g s was t a k e n , a n d t h i s v a l u e was u s e d t o c o m p a r e c o o r d i n a t e s o f a p r i s m f r o m one o b s e r v a t i o n c a m p a i g n t o t h e n e x t . U n u s u a l movements w e r e n o t e d f o r t h e p r i s m s . I n some c a s e s a p r i s m a c t u a l l y i n c r e a s e d i n e l e v a t i o n , w h i l e o t h e r s a p p e a r e d t o move i n a c i r c u l a r f a s h i o n . T h i s w o u l d i n d i c a t e e r r o r s i n t h e o b s e r v a t i o n s a n d i n s t r u m e n t a t i o n w e r e n o t b e i n g a c c o u n t e d f o r . T h e m a n u f a c t u r e r ' s s t a t e d a c c u r a c y f o r t h e K e r n E l i s two a r c s e c o n d s f o r a n a n g l e m e a s u r e d i n t h e d i r e c t a n d r e v e r s e mode . T h i s c o r r e s p o n d s t o a l i n e a r e r r o r i n h o r i z o n t a l p o s i t i o n o f 3 . 8 mm o v e r a d i s t a n c e o f 400 m, w h i c h i s t h e s h o o t i n g d i s t a n c e i n t h e V e r t i c a l L i m b . H o w e v e r , t h e e r r o r i n t h e v e r t i c a l a n g l e m e a s u r e m e n t i s much g r e a t e r . T h i s i s d u e t o t h e e f f e c t o f r e f r a c t i o n a l o n g t h e l i n e o f s i g h t c a u s e d b y i n h o m o g e n e o u s a t m o s p h e r i c c o n d i t i o n s , w h i c h c a u s e l i g h t r a y s t o b e n d . T h e u n c e r t a i n t y i n t h e v e r t i c a l a n g l e c a n b e a s l a r g e a s t e n a r c s e c o n d s , w h i c h c o r r e s p o n d s t o a n e r r o r i n e l e v a t i o n o f 2 . 0 c m . T h e d i s t a n c e m e t e r i s a l s o a s o u r c e o f e r r o r w i t h a s t a t e d s t a n d a r d d e v i a t i o n o f 3 mm + 2ppm. T h i s s u r v e y n e t w o r k was b a s e d o n t h e f a c t t h a t s t a t i o n 506 was s t a t i o n a r y . U s i n g t h e new s u r v e y n e t w o r k a n d e q u i p m e n t s t a t i o n 506 was f o u n d t o b e m o v i n g . T h i s means 96 t h a t u p u n t i l M a r c h 1988 t h e d e f o r m a t i o n s o f 506 w e r e r e f l e c t e d i n t h e c o o r d i n a t e s o f e a c h p r i s m . 9 . 3 CURRENT NETWORK 9 . 3 . 1 SURVEY EQUIPMENT T h e new s u r v e y e q u i p m e n t , p u t i n t o o p e r a t i o n i n M a r c h o f 1 9 8 8 , c o n s i s t e d o f a W i l d T 2 0 0 0 e l e c t r o n i c t h e o d o l i t e a n d a D I 2 0 0 0 d i s t a n c e m e t e r . A n a u t o m a t i c d a t a c o l l e c t o r v a s t l y s u p e r i o r t o t h e K e r n ' s was u s e d i n t h e f i e l d , a n d d a t a was s u b s e q u e n t l y i n t e r f a c e d w i t h a c o m p u t e r f o r p e r m a n e n t r e c o r d a n d a n a l y s i s . T h i s t h e o d o l i t e a n d d i s t a n c e m e t e r w e r e o n l y u s e d b y t h e s u r v e y e n g i n e e r f o r m o n i t o r i n g p u r p o s e s . 9 . 3 . 2 METHODOLOGY AND ACCURACY T h e new s u r v e y n e t w o r k c o n s i s t e d o f two known p o i n t s , s t a t i o n s 701 a n d 7 0 2 , l o c a t e d w e l l b e h i n d t h e u n s t a b l e z o n e o n t h e n o r t h w a l l . S t a t i o n 702 was a p e r m a n e n t l y p l a c e d p r i s m a n d a c t e d a s a b a c k s i g h t , a n d s t a t i o n 701 was a p e r m a n e n t p i l l a r w h i c h a c t e d a s a t r a n s i t s t a t i o n a n d b a c k s i g h t . On t h e s o u t h w a l l s t a t i o n s 506 a n d 602 w e r e u s e d t o s u r v e y i n t h e n o r t h w a l l , b o t h w e r e l o c a t e d o n u n s t a b l e z o n e s . T h e s e s t a t i o n s t h e r e f o r e h a d t o b e s u r v e y e d i n e v e r y t i m e , s o t h e p r i s m c o o r d i n a t e s o n t h e n o r t h w a l l c o u l d b e c a l c u l a t e d i n r e l a t i o n t o t h e known f i x e d p o s i t i o n s , 97 s t a t i o n s 701 a n d 7 0 2 . B o t h s t a t i o n s , 602 a n d 5 0 6 , a r e f o r e s i g h t s f r o m s t a t i o n 7 0 1 , a n d b o t h 701 a n d 702 a r e b a c k s i g h t s f r o m 602 a n d 506 ( s e e p i t s t a t u s map f o r t h e l o c a t i o n s o f t h e s e s t a t i o n s ) . T h e p r o c e d u r e b e f o r e a n y r e a d i n g s w e r e t a k e n was t o c a r e f u l l y l e v e l a n d c a l i b r a t e t h e i n s t r u m e n t t o e n s u r e maximum a c c u r a c y . T h e t e m p e r a t u r e a n d p r e s s u r e w e r e m e a s u r e d a n d t h e a p p r o x i m a t e s c a l e c o r r e c t i o n a p p l i e d t o a l l d i s t a n c e s . A b a c k s i g h t w i t h a known d i s t a n c e was u s e d t o c h e c k t h e a c c u r a c y o f t h e d i s t a n c e m e t e r , a n d l a t e r t h e c a l c u l a t e d p o s i t i o n s o f 701 a n d 702 w e r e c o m p a r e d t o t h e i r known l o c a t i o n s . A min imum o f 5 d i s t a n c e r e a d i n g s w e r e t a k e n u n t i l t h e s t a n d a r d d e v i a t i o n was 0 . 4 mm. A min imum o f 2 s e t s o f a n g l e m e a s u r e m e n t s w e r e t a k e n u n t i l t h e e r r o r r e p o r t e d was 1 a r c s e c o n d . T h e d a t a c o l l e c t o r r e d u c e d t h e d a t a t o a n a v e r a g e a n g l e a n d d i s t a n c e f o r e a c h s i g h t i n g . I n t h e o f f i c e a l e a s t s q u a r e s a d j u s t m e n t p r o g r a m was r u n o n a n IBM X T , w h i c h c a l c u l a t e d t h e c o o r d i n a t e s o f e a c h p r i s m a n d t e s t e d t h e p o s i t i o n b y c o m p a r i n g i t s l o c a t i o n w i t h o t h e r p r i s m s . A f t e r t h e c o o r d i n a t e s w e r e f o u n d a w e i g h t e d p r o j e c t i o n p r o g r a m was r u n , w h i c h t e s t e d t o s e e i f t h e t h e o d o l i t e was s e t u p d i r e c t l y o v e r s t a t i o n 701 o r t o s e e i f 701 a n d 702 h a d m o v e d . T h e s u r v e y d a t a a c c u r a c y i n c r e a s e d e n o r m o u s l y w i t h t h e new e q u i p m e n t a n d p r o c e d u r e s . L e s s o s c i l l a t i o n i n t h e c u m u l a t i v e h o r i z o n t a l movements became a p p a r e n t a n d t o some 98 e x t e n t t h e r e was l e s s o s c i l l a t i o n i n c u m u l a t i v e v e r t i c a l m o v e m e n t s ( F i g u r e 3 0 ) . T o f u r t h e r i n c r e a s e t h e a c c u r a c y o f t h e v e r t i c a l movements was n o t p o s s i b l e d u e t o t h e e f f e c t o f r e f r a c t i o n a l o n g t h e l i n e o f s i g h t . T h e m a n u f a c t u r e r ' s s t a t e d a c c u r a c y f o r t h e W i l d T 2 0 0 0 i s 0 . 5 a r c s e c o n d s a n d f o r t h e DI2000 i t i s 1 mm + l p p m . T h i s e q u i p m e n t a n d d a t a r e d u c t i o n p r o c e d u r e i s s t a t e - o f - t h e - a r t p r o v i d i n g f o u r t i m e s m o r e a c c u r a c y f o r a n g l e m e a s u r e m e n t s a n d s e v e n t i m e s m o r e a c c u r a c y f o r d i s t a n c e m e a s u r e m e n t s t h a n t h e i n d u s t r y s t a n d a r d . T h i s h i g h d e g r e e o f a c c u r a c y was r e q u i r e d i n t h e V e r t i c a l L i m b b e c a u s e a m i n e a n d m o n i t o r m e t h o d o f m i n i n g was b e i n g u s e d a n d t h e movement r a t e s w e r e i n t h e o r d e r o f m i l l i m e t r e s p e r d a y . 99 CUMULATIVE MOVEMENT vs TIME STATION 7051 23-Jun-88 27-Jul-88 24-Aug-88 06-Sap-88 17-Sep-88 TIME (doy») 1988 • HORIZONTAL MOVEMENT + VERTICAL MOVEMENT F i g u r e 30 C u m u l a t i v e movement v s t i m e p l o t s h o w i n g v e r y l i t t l e o s c i l l a t i o n i n t h e h o r i z o n t a l movement c u r v e a n d o n l y some i n t h e v e r t i c a l movement c u r v e . 10 . E V A L U A T I O N OF J U L Y 2 7 . 1987 T O P P L I N G F A I L U R E On t h e n i g h t o f J u l y 2 7 / 2 8 , 1987 t h e 1720 b e n c h f a c e u n d e r w e n t a t o p p l i n g f a i l u r e . T h e f a i l u r e was n o t u n e x p e c t e d a n d t h e V e r t i c a l L i m b h a d b e e n c l o s e d s e v e r a l d a y s p r i o r t o f a i l u r e . Work i n t h e V e r t i c a l L i m b was d i s c o n t i n u e d f o r one a n d a h a l f m o n t h s t o a l l o w t h e 3 0 , 0 0 0 b a n k c u b i c m e t r e s o f f a i l u r e m a t e r i a l t o b e r e m o v e d a n d o t h e r r e m e d i a l m e a s u r e s t o b e t a k e n . 1 0 . 1 L O C A T I O N OF F A I L U R E T h e f a i l u r e o c c u r r e d b e t w e e n s e c t i o n l i n e s 34890 a n d 34950 a n d e n c o m p a s s e d t h e b e n c h f a c e b e t w e e n e l e v a t i o n 1725 a n d 1750 m ( F i g u r e s 31 a n d 3 2 ) . T h e c r e s t a r e a b e t w e e n s e c t i o n s 34800 a n d 35000 showed s i g n s o f d i s t r e s s i n t h e f o r m o f t e n s i o n c r a c k s s p a c e d a t i n t e r v a l s o f 10 cm t o s e v e r a l m e t r e s . F a i l u r e was c o n f i n e d t o t h e one b e n c h f a c e , a n d t h e m a t e r i a l , w h i c h f a i l e d , was t h e H u l c r o s s s h a l e s e q u e n c e . T h e H u l c r o s s , w i t h a c l o s e r b e d d i n g j o i n t s p a c i n g a n d l o w e r s h e a r s t r e n g t h t h a n t h e G a t e s i s m o r e p r o n e t o t o p p l i n g . 1 0 . 2 MONITORING AND DRAINAGE NETWORK I N P L A C E D r a i n a g e was i n s t a l l e d o n l y j u s t p r e v i o u s t o t h e f a i l u r e e v e n t a n d e x i s t e d o n l y o n t h e 1690 b e n c h . T h e h o r i z o n t a l d r a i n s w e r e 20 m l o n g a n d p o s i t i o n e d o n 30 m c e n t r e s , b u t a s t h e f a i l u r e o c c u r r e d a b o v e a n d b e h i n d t h e 101 102 S 1750-1720 -1690— 1660-1640-STABLE BY PRISMS ZONE OF RECOGNIZED BLAST DAMAGE OESIO ^ STABLE. I FARTHEST BACK BREAK INFERRED WORST CASE FAILURE PLANE G A T E S F O R M A T I O N INTERBEOOEO SANDSTONE AND SHALES WITH COAL H U L C R O S S F O R M A T I O N SANDY SHALE WITH BENTONITE CLAY LAYERS LEGEND INSTALLED DRAINS (JULY 1987) RECOMMENDED HORIZONTAL DRAINS U TENSION CRACKS (DEPTH UNKNOWN) f PRISM MONITORS (AUGUST 1987) V BEDDING DIP Figure 32 Cross-section of July 27, 1987 toppling f a i l u r e along section 34900. 103 d r a i n s t h e y h a d l i t t l e e f f e c t . F i g u r e 32 shows t h e e x i s t i n g d r a i n a g e a n d t h e h o r i z o n t a l d r a i n s p r o p o s e d a f t e r t h e f a i l u r e h a d o c c u r r e d . Due t o t h e l a c k o f d r a i n a g e t h e s l o p e c a n h a v e h i g h w a t e r p r e s s u r e s g e n e r a t e d i n b e h i n d t h e w a l l , a n d t h i s w o u l d b e a m a j o r c o n t r i b u t i n g f a c t o r t o t h e m e c h a n i s m o f f a i l u r e . M o n i t o r i n g was i n p l a c e p r i o r t o J u l y 2 7 , 1 9 8 7 , b u t few p r i s m s e x i s t e d i n t h e a r e a o f t h e b e n c h s c a l e f a i l u r e ( F i g u r e 3 1 ) . B e l o w 1690 m no p r i s m s w e r e i n p l a c e , a n d t h e a c c u r a c y o f t h e s u r v e y i n s t r u m e n t was a p r o b l e m . T a b l e 6 shows t h e p r i s m s i n p l a c e b e f o r e a n d a f t e r t h e f a i l u r e a n d t h e i r a p p r o x i m a t e movement r a t e s . T a b l e 6 P r i s m s l o c a t e d i n t h e f a i l u r e a r e a a n d t h e i r movement r a t e s . SUMMARY OF PRISMS H O R I Z O N T A L MOVEMENT R A T E S L O C A T E D ON T H E MARMOT V E R T I C A L L I M B APPROX H O R I Z . M O V ' T S E C T . P R I S M # MONITORING : I N T E R V A L R A T E (mm/day) COMMENT 34900 1 7 5 0 - 0 7 J u l 3 1 / 8 7 — J a n 8 / 8 8 3 . 0 1 7 5 0 - 0 6 J u l 3 1 / 8 7 - A u g 2 5 / 8 7 7 . 0 1 7 5 0 - 0 5 J u l 3 1 / 8 7 - A u g 2 5 / 8 7 3 . 5 1 7 5 0 - 0 4 J u n 1 8 / 8 7 - J u l 2 7 / 8 7 1 9 . 3 l o s t 1 7 2 0 - 0 6 A u g 5 / 8 7 - A u g 1 8 / 8 7 5 . 8 1 7 2 0 - 0 5 J u n 8 / 8 6 - J u l 3 / 8 7 0 . 8 J u l 3 / 8 7 - J u l 2 7 / 8 7 2 0 . 7 l o s t 1 6 9 0 - 0 5 A u g 6 / 9 7 - A u g 3 5 / 8 7 s t a b l e 1 6 6 0 - 0 5 A u g 6 / 8 7 - A u g 1 7 / 8 7 s t a b l e 1 6 4 0 - 0 5 A u g 5 / 8 7 — A u g 2 5 / 8 7 s t a b l e 35000 50401 J u n 1 6 / 8 6 — N o v 6 / 8 7 3 . 0 1 7 5 0 - 0 3 J u l 2 3 / 8 7 - J u l 2 7 / 8 7 2 0 . 0 1 7 2 0 - 0 4 J u l 1 0 / 8 7 - J u l 3 1 / 8 7 < 1 . 0 104 The two prisms located on the f a i l u r e 1750-04 and 1720-05 were both l o s t but the slope appears to have been moving at rates of approximately 20 mm/day p r i o r to the actual f a i l u r e . This magnitude of movement would indicate the area was undergoing active toppling. A f t e r the f a i l u r e movement rates above 1720 m were s t i l l high, but t h i s would be expected as the wall adjusted to the f a i l u r e . The pl o t s of t o t a l movement for prisms 50401, 1750-03, 1750-04 and 17200-05 are shown i n Figures 33 and 34. Prism 50401 gave no warning of impending f a i l u r e , but 1750-03, 1750-04 and 1720-05 show the movement rates increasing with constant acceleration. Prism 1720-05 shows that the movement rates had been accelerating at a constant rate for over a year and then i n early July the movement rates accelerated to f a i l u r e . This jump i s independent of r a i n or b l a s t i n g , but r a i n f a l l during the middle of J u l y would have aggravated the s i t u a t i o n . Without the heavy r a i n on the evening before the f a i l u r e the bench would l i k e l y have f a i l e d . Prisms 1750-03, 1750-04 and 1720-05 are t y p i c a l p l o t s f o r a toppling f a i l u r e , with most of the movement occurring i n the hori z o n t a l plane. See Appendix G f o r the monitoring data for the J u l y 27, 1987 f a i l u r e . Extensometers stations were set up on the bench face between 1720 and 1750 m elevations and one s t a t i o n existed behind the 1750 bench crest . Unfortunately measurements 105 CUMULATIVE NET MOVEMENT vs TIME STATION S0401 0.38 -1 16-Jun-M 11 -Deo—86 18-Jun-87 19-Aug-87 24-S*p-S7 TIME (days) 1086/87 • HORIZONTAL MOVEMENT + VERTICAL MOVEMENT CUMULATIVE NET MOVEMENT vs TIME STATION 175003 aoe - i -0.03 t . • — . . 1 . . . . 1 1 . 1 1 1 1 1 1 1 1 1 18-0tm-S7 23-M-87 02-Aug-87 13-Aug-67 2S-Aug-67 TIME (day*) 1987 • HORIZONTAL MOVEMENT + VERTICAL MOVEMENT F i g u r e 33 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 50401 a n d 1 7 5 0 - 0 3 . 106 1 3 CUMULATIVE NET MOVEMENT vs TIME STATION 179004 0.35 -0.1 18-Jun—87 • HORIZONTAL MOVEMENT 1 02-JUI-87 22-Jul-a7 24-Jut-87 27-Jul-87 TIME (day*) 1987 + VERTICAL MOVEMENT 3 3 0.7 0.6 -(L9 -0.4 -OS -OJZ -0.1 -16-Jun-Sa CUMULATIVE NET MOVEMENT vs TIME STATION 172006 28-44-67 • HORIZONTAL MOVEMENT TIME (day*) 1088/87 + VERTICAL MOVEMENT F i g u r e 34 P l o t o f c u m u l a t i v e n e t movement v s t i m e f o r s t a t i o n s 1 7 5 0 - 0 4 a n d 1 7 2 0 - 0 5 . 107 w e r e n o t t a k e n f r o m J u l y 5 , 1987 o n w a r d s , b u t t h e m e a s u r e m e n t s t a k e n o v e r a 20 d a y p e r i o d s h o w e d t h e c r a c k s t o b e o p e n i n g a n d c l o s i n g a t t h e r a t e o f a c o u p l e o f m i l l i m e t r e s p e r d a y . T h e m e a s u r e m e n t s w e r e made o v e r c r a c k s l o c a t e d o n t h e s l i d e m a s s , w h i c h e x p l a i n s t h e i n c r e a s i n g a n d d e c r e a s i n g c r a c k a p e r t u r e s . 1 0 . 3 P R E - F A I L U R E DEVELOPMENTS T e n s i o n c r a c k s d u e t o a c c u m u l a t e d movement w e r e f i r s t o b s e r v e d i n t h e c r e s t a r e a t h e p r e v i o u s s p r i n g , a l t h o u g h , f r o m s u r v e y d a t a t h e w a l l b e g a n u n d e r g o i n g t o p p l i n g f a i l u r e a t l e a s t a y e a r b e f o r e t h e f a i l u r e o c c u r r e d . D u r i n g t h e summer m o n t h s t h e c r a c k s c o n t i n u e d t o o p e n u p , a n d d u r i n g a t w o d a y p e r i o d p r i o r t o t h e f a i l u r e movement r a t e s i n t h e a r e a w e r e a t a p p r o x i m a t e l y 20 m m / d a y . On M o n d a y , J u l y 2 7 , 1987 c r a c k s w e r e o b s e r v e d t o b e s p a c e d a t i n t e r v a l s o f 10 cm t o s e v e r a l m e t r e s , a n d t h e f a r t h e s t b a c k t e n s i o n c r a c k was a p p r o x i m a t e l y 15 cm w i d e . A f t e r t h e f a i l u r e t h i s c r a c k o p e n e d u p t o 30 cm w i t h a 30 cm down d r o p . B e t w e e n 6 : 0 0 pm a n d 8 : 0 0 pm a p p r o x i m a t e l y 10 mm o f r a i n f e l l . A r o a d w h i c h l e d t o t h e c r e s t a r e a a c t e d a s a s t r e a m c h a n n e l a n d w a t e r d u r i n g t h e r a i n e v e n t was o b s e r v e d t o b e , r u n n i n g i n t o t h e t e n s i o n c r a c k s . L a t e r t h a t n i g h t t h e b e n c h f a c e f a i l e d . 108 10.4 CAUSES OF THE TOPPLING FAILURE Three causes of the f a i l u r e have been i d e n t i f i e d : inappropriate wall design, b l a s t i n g damage to the wall and high water pressures i n tension cracks behind the wall. Although the slope underwent a toppling f a i l u r e sudden f a i l u r e i s not c h a r a c t e r i s t i c . Generally t h i s type of f a i l u r e progresses slowly f o r a year or more. The bench face appeared to be v i o l e n t l y pushed away from the wall. The energy required for t h i s type of f a i l u r e came from the hydrostatic water pressures generated i n tension cracks. The force generated on the toppling mass i s calculated from the following equation: F = 1/2 K-H2 Where F = Lateral force (kN/m) = S p e c i f i c weight of water (N/m3 H = Height of water i n the crack (m) Very high l a t e r a l forces can be generated with a minimum r a i n f a l l i f the crack aperture i s small and water cannot drain out to the bench face. Both of these conditions were met. Water was channelled to the tension cracks by the road, and bentonitic clay layers near the Hulcross Gates contact prevented natural drainage of the slope. The t h e o r e t i c a l Gates Hulcross contact i s on the bench face between elevations 1720 and 1750 m. I n s t a l l a t i o n of h o r i z o n t a l drains on the 1720 bench would have r e l i e v e d the water pressures i n the wall and prevented the v i o l e n t type f a i l u r e . The r e s u l t was f a i l u r e material accumulated 109 on the lower benches and p i t f l o o r . This meant the V e r t i c a l Limb had to remain closed u n t i l a l l the f a i l u r e material had been removed from the benches and p i t f l o o r . The inappropriate wall design meant the bench heights for the Hulcross were too high. From experience and computer generated models the Hulcross can be cut safely to a bench height of 15 m and the Gates to a bench height of 30 m (Stewart, 1982, 1983, 1985(A)). In the V e r t i c a l Limb the Hulcross was cut to a bench height of 20 m. The Gates Formation made up the lower part of the bench face, but the Upper Gates i s poor qua l i t y rock and i s considered to behave l i k e the Hulcross Formation. The b l a s t i n g damage i s a problem i n the Hulcross Formation and to some degree i n the Gates as well. The Hulcross i s more prone to toppling than the Gates due to a bedding j o i n t frequency of 1 every 40 cm, which compares to one every 1.5 m i n the Gates Formation. This high frequency i s due to the high pressured gases opening up partings along bedding planes. The 1735 bench face had been v i s i b l y b l a s t damaged, which meant the toe of the f a i l u r e slope was unable to counter the large forces generated i n t h i s area. Figure 32 shows the b l a s t damaged area, and i t s association with the f a i l u r e . F a i l u r e of t h i s bench face would have occurred without the r a i n . The monitoring data suggests the slope began to f a i l the year before, and the movement rates began to 110 accelerate i n early July. The inappropriate wall design and b l a s t i n g damage were enough to cause f a i l u r e , and the r a i n only contributed to the v i o l e n t nature of the f a i l u r e . 10.5 REMEDIAL MEASURES TAKEN The remedial measures consisted of c o n t r o l l i n g surface runoff, removing the f a i l u r e material, resloping the crest area and i n s t a l l i n g drainage. To gain a better understanding of the groundwater regime i n the f a i l u r e area two pneumatic piezometers were i n s t a l l e d . One of the two piezometers, worked and t h i s suggested the water table was located at 1720 m, well below the basal f a i l u r e plane. Therefore, remedial measures had to deal with surface runoff and a transient water table. Horizontal drains were i n s t a l l e d along the d i f f e r e n t bench faces to d r a i n water out of the slope. Ditching was c a r r i e d out to d i r e c t water away from the slope c r e s t area. A culvert pipe was to be i n s t a l l e d i n the creek behind the wall but t h i s was never done. The f a i l u r e material was removed by bulldozer which pushed the material into the p i t . The operator started at the top and once the f a i l e d bench had been scaled the crest area was re-contoured to make the cres t area as f l a t as possible. The toppling f a i l u r e s were driven from the material above so f l a t t e n i n g the crest area should have helped to prevent future f a i l u r e s . The bulldozer then moved 111 down t o t h e l o w e r s a f e t y b e r m s t o p u s h t h e t a l u s t h a t c o l l e c t e d t h e r e i n t o t h e p i t . T h e r e m o v a l o f t h e f a i l u r e m a t e r i a l t o o k a p p r o x i m a t e l y l j m o n t h s . M o n i t o r i n g , a l t h o u g h n o t a r e m e d i a l m e a s u r e , h a d t o b e u p g r a d e d o v e r t h e e n t i r e w a l l , s o u t h e a s t o f t h e n o s e a r e a , a n d i n p a r t i c u l a r i n t h e a r e a o f t h e f a i l u r e . T h e s u r v e y d a t a c o l l e c t e d t o d a t e was u s e f u l , b u t l a r g e m o v e m e n t s w e r e n e e d e d b e f o r e a n y r e l i a b l e i n t e r p r e t a t i o n c o u l d b e m a d e . T h e f u t u r e m i n e p l a n c a l l e d f o r a 40 m h i g h b e n c h f a c e a t t h e b a s e o f a n 120 m h i g h w a l l p r o n e t o t o p p l i n g , s o v e r y a c c u r a t e m o n i t o r i n g was r e q u i r e d t o e n s u r e t h a t p e r s o n n e l a n d e q u i p m e n t w e r e n o t e x p o s e d t o u n s a f e c o n d i t i o n s . T h i s r e q u i r e d p u r c h a s i n g a new t h e o d o l i t e a n d e m p l o y i n g a s u r v e y e n g i n e e r . 112 11. EVALUATION OF SEPT 18. 1988 TOPPLING FAILURE In the early morning of September 18, 1988 a major toppling f a i l u r e occurred, which deposited an estimated 135,000 LCM's (loose cubic meters) of material on the p i t f l o o r . Another 30,000 LCM's of f a i l u r e material remained on the w a l l . The f a i l u r e was not unexpected, so precautions had been taken. Men and equipment were removed 29 hours before the event and a l l access to the p i t was sealed o f f . Detailed monitoring had been done on a regular basis f o r four months and continued r i g h t up to the day of f a i l u r e . Unfortunately coal, which was to be subbed from 1600 to 1577 m and located west of section l i n e 34750, was buried by the f a i l u r e . R e h a b i l i t a t i o n of the slope was not thought p r a c t i c a l by mine management, so the affected area of the p i t was abandoned. 11.1 LOCATION OF FAILURE The f a i l u r e occurred between section l i n e s 34770 and 34940 and i s assumed to encompass the bench face between elevation 1660-1720 m (Figures 35 and 36). The exact l o c a t i o n of the toe of the f a i l u r e i s not known due to the broken material which i s covering the wall. Cracks were c l e a r l y v i s i b l e on berms 1690 and 1720 m and behind the crest of the wall between section l i n e s 34750 and 35900 p r i o r to the f a i l u r e . This f a i l u r e , unlike the previous one, encompassed Hulcross and Gates material and involved more than one bench. 113 1 1 4 8 S T A B L E J B Y PRISMS I750 — 1720 -.STABLE. F T \ \ CL^V LAVS^«S 1 \ H U L C R O S S F O R M A T I O N SANDY SHALE WITH BENTONITE CLAY LAYERS LEGEND INSTALLED DRAINS (SEPTEMBER 1988) \1 TENSION CRACKS (DEPTH UNKNOWN) f PRISM MONITORS (SEPTEMBER 1988) ^ BEDDING DIP Figure 36 Cross-section of September 18, 1988 toppling f a i l u r e along section 34850. 115 1 1 . 2 MONITORING AND DRAINAGE NETWORK I N P L A C E T h e t o p p l i n g f a i l u r e i n 1987 r e s u l t e d f r o m n o t d r a i n i n g t h e s l o p e . I n t e n s i v e d r a i n a g e was i n s t a l l e d i n 1 9 8 7 / 8 8 w h i c h r e c t i f i e d t h e p r o b l e m . F i g u r e s 35 a n d 3 6 show t h e l o c a t i o n o f d r a i n s ( d a s h e d l i n e s ) , a n d t h e i n t e n s i t y o f d r a i n a g e . U n f o r t u n a t e l y i n s t a b i l i t y o f t h e w a l l may h a v e r e a c h e d t h e p o i n t t h a t when d r a i n a g e was f i n a l l y i n s t a l l e d i t was t o o l a t e . T r a n s i e n t h y d r o s t a t i c f o r c e s h a d a l r e a d y h e l p e d t o i n i t i a t e f a i l u r e . M o n i t o r i n g o f t h i s p a r t o f t h e w a l l h a d b e e n i n t e n s i f i e d a f t e r t h e J u l y 2 7 t h f a i l u r e a n d t h e new m o n i t o r i n g n e t w o r k was b e i n g u s e d . S u r v e y d a t a was r e l i a b l e a n d u s e d e x t e n s i v e l y t o p r e d i c t when t h e f a i l u r e was l i k e l y t o o c c u r . T a b l e 7 shows t h e p r i s m s i n p l a c e b e f o r e t h e f a i l u r e a n d t h e i r a p p r o x i m a t e movement r a t e s j u s t p r i o r t o t h e e v e n t . M o v e m e n t r a t e s , f r o m T a b l e 7 , c o n f i r m a t o p p l i n g f a i l u r e a n d a l s o g i v e a c l u e a s t o w h e r e t h e f a i l u r e d a y l i g h t e d . T h e movement r a t e s a r e h i g h e s t a t t h e t o p o f t h e f a i l u r e a n d d e c r e a s e w i t h d e p t h . T h i s i s t y p i c a l o f a t o p p l i n g t y p e f a i l u r e . T h e s t a t i o n s s t a r t i n g w i t h 76 o r 74 a r e l o c a t e d o n t h e 1660 a n d 1640 b e n c h e s a n d a p p e a r t o b e m o v i n g m a i n l y a s a r e s u l t o f s t r e s s r e l i e f . T h i s w o u l d i m p l y t h e t o e o f t h e f a i l u r e i s b e t w e e n 1660 a n d 1690 m. A l s o o f i n t e r e s t i s s t a t i o n 7 0 5 1 , w h i c h h a s t h e h i g h e s t r e a d i n g , a n d i s a p p r o x i m a t e l y o n t h e c e n t r e l i n e o f t h e 116 Table 7 Prisms located i n the f a i l u r e area and t h e i r movement rates j u s t p r i o r to the event. SUMMARY OF PRISMS HORIZONTAL MOVEMENT RATES LOCATED ON THE MARMOT VERTICAL LIMB APPROX HORIZ. MOV'T SECT. PRISM # MONITORING INTERVAL RATE (mm/day) COMMENT 34700 7402 Jun 30/88 — Sep 25/88 0.8 34800 7051 Jun 23/88 - Sep 17/88 41.0 l o s t 7903 Aug 27/88 - Sep 17/88 4.0 l o s t 7602 May 16/88 - Sep 12/88 1.5 l o s t 7603 May 16/88 - Sep 12/88 1.0 l o s t 7401 Jun 30/88 — Sep 12/88 1.0 l o s t 34850 172501 Jun 24/88 — Sep 17/88 35.4 l o s t 7902 May 16/88 - Jun 30/88 10.0 l o s t 7601 May 16/88 - Sep 12/88 1.4 l o s t 7404 J u l 27/88 Sep 12/88 1.0 l o s t 34900 1750-06 Dec 8/87 - Sep 25/88 25.8 7901 May 16/88 — Sep 17/88 16.7 l o s t 34950 1750-04 Feb 22/88 - Sep 25/88 4.0 7905 May 29/88 - Sep 25/88 0.8 7604 J u l 27/88 — Sep 25/88 1.1 s l i d e . From these observations the following conclusions can be made. The top and middle part of the s l i d e has the highest movement rates and, the s l i d e would appear to have been slowed down at the boundaries due to side f r i c t i o n . The l a s t conclusion i s an important observation because most computer models are two dimensional and do not take side 117 f r i c t i o n into account. This may r e s u l t i n a computer simulation predicting f a i l u r e , when i n fact the wall w i l l stand unsupported. On the following f i v e pages plots of cumulative net movement versus time are plotted. Stations 175006, 7901, 172501, 7902 and 7051 show t y p i c a l plots of a wall toppling. The horizontal cumulative movement i s accelerating to f a i l u r e , while the v e r t i c a l cumulative movement i s more subdued. The small i n i t i a l v e r t i c a l displacements followed by s l i g h t l y larger displacements p r i o r to f a i l u r e are i n d i c a t i v e of toppling. Predicting when f a i l u r e w i l l occur from these pl o t s i s a simple process. Also, from these p l o t s , jumps i n cumulative movement can be seen during mid June and mid August. Climatic records show heavy r a i n f a l l , of 18.6 mm and 43.4 mm respectively during these periods. This would indicate the wall, although drained, was very s e n s i t i v e to transient water- tables. Stations 7601, 7602 and 7603 show minor toppling tendencies, but most of the movement i s due to stress r e l i e f . Stations 7602 and 7603 show how well the monitoring network was functioning. The hori z o n t a l and v e r t i c a l cumulative movement curves almost track each other exactly. Station 7404, located on the 1640 m berm, shows no tendency to topple and i s undergoing stress r e l i e f (Appendix H f o r the monitoring data f o r the September 18, 1988 f a i l u r e ) . 118 CUMULATIVE NET MOVEMENT vs TIME STATION 17S006 Oa-Oae-87 HORIZONTAL MOVEMENT i [—i—i—i—i-1—i—r—\—i i i i i i i | 26-Apr-SS 21-Jul-SS 03-S*p-88 22-S*p-88 TIME (day*) 1987 - 1988 + VERTICAL MOVEMENT 1 2 3 O CUMULATIVE NET MOVEMENT vs TIME STATION 7901 0.35 -0.08 --0.1 16-May-8B 17-Jun-88 21-Jul-l HORIZONTAL MOVEMENT - i — i — i — i — | — i — i — i — | — i — i — i — p 17-Aug-8B 03-S*p-88 15-S*p-88 TIME (days) 1988 + VERTICAL MOVEMENT Figure 3 7 Plot of cumulative net movement vs time f o r stations 175006 and 7901. 119 3 3 2 3 O CUMULATIVE NET MOVEMENT vs TIME STATION 172501 18—Jun • HORIZONTAL MOVEMENT 06-Jul 26-Jul 15-Aug 04-Sap 24-S«p TIME (DAYS) 1988 + VERTICAL MOVEMENT 1 3 2 3 O -O01 18-Moy-88 • HORIZONTAL MOVEMENT CUMULATIVE NET MOVEMENT vs TIME STATION 7902 29-Moy-8B 17-jun-ae TIME (days) 1088 + VERTICAL MOVEMENT 30-Jun-88 Figure 38 Plot of cumulative net movement vs time for stations 172501 and 7902. 120 i 3 2 3 U 0.1 0.09 16 Moy *8fl HORIZONTAL MOVEMENT CUMULATIVE NET MOVEMENT vs TIME STATION 7801 17-Jun-88 17-AUO-88 12-S«p-88 TIME (days) 1088 + VERTICAL MOVEMENT 1 3 2 3 0.02 -0.020 27-jui-aa HORIZONTAL MOVEMENT CUMULATIVE NET MOVEMENT vs TIME STATION 7404 10-Aug-8B 24-Aug-88 OS-Sap-SB TIME (daya) 1988 + VERTICAL MOVEMENT Figure 39 Plot of cumulative net movement vs time for stations 7601 and 7404. 121 CUMULATIVE MOVEMENT vs TIME STATION 7051 23-Jun-M 27-Jul-8e 24-Aug-68 06-Sap-88 17-S*p-«8 TIME (days) 1088 • HORIZONTAL MOVEMENT + VERTICAL MOVEMENT CUMULATIVE NET MOVEMENT vs TIME STATION 7003 0.06 - i 27-Aug-88 03-S«p-88 09-S«p-88 15-S«p-88 TIME (days) 1988 • HORIZONTAL MOVEMENT + VERTICAL MOVEMENT Figure 4 0 Plot of cumulative net movement vs time f o r stations 7051 and 7903. 122 2 1 3 3 3 O 18-May-88 HORIZONTAL MOVEMENT CUMULATIVE NET MOVEMENT vs TIME STATION 7602 17-Jun-8e 21-JUI-8 17-Aug-88 TIME (day*) 1088 + VERTICAL MOVEMENT 12-Sep-88 1 3 3 3 O CUMULATIVE NET MOVEMENT vs TIME STATION 7603 16-May-88 HORIZONTAL MOVEMENT 17-Jun-88 21-dul-B8 17-Aug-88 12-Sep-88 TIME (daya) 1088 + VERTICAL MOVEMENT Figure 41 Plot of cumulative net movement vs time f o r stations 7602 and 7603. 123 T h r e e e x t e n s o m e t e r s t a t i o n s w e r e i n s t a l l e d , b u t o n l y two w e r e u s e f u l . T h e t h i r d , l o c a t e d b e h i n d t h e c r e s t a n d s t r a d d l i n g t h e b a c k s c a r p was i n s t a l l e d o n l y d a y s b e f o r e t h e f a i l u r e . T h e f i r s t e x t e n s o m e t e r s t a t i o n was i n s t a l l e d i n e a r l y May a n d l o c a t e d a c r o s s t h e 1690 m b e r m . U n f o r t u n a t e l y o n l y s e v e n r e a d i n g s w e r e t a k e n , a n d o f t h e s e , f i v e w e r e t a k e n i n M a y . T h e m o s t u s e f u l s t a t i o n was l o c a t e d o n t h e 1725 m b e r m a n d s p a n n e d a l a r g e c r a c k . R e a d i n g s w e r e t a k e n o n t h e 9 t h , 1 2 t h , 1 5 t h , 1 6 t h , a n d 1 7 t h o f S e p t e m b e r a n d showed movement r a t e s a c c e l e r a t i n g f r o m 4 t o 5 t o 11 t o 25 t o 75 m m / d a y . T h e e x t e n s o m e t e r s t a t i o n was e n t i r e l y l o c a t e d o n t h e s l i d e , s o t h e s e movement r a t e s d o n o t r e f l e c t o v e r a l l m o v e m e n t . 124 1 1 . 3 P R E - F A I L U R E DEVELOPMENTS On J u l y 2 7 , 1987 a m i n o r t o p p l i n g f a i l u r e o c c u r r e d i n t h e same v i c i n i t y a s t h e S e p t e m b e r f a i l u r e . D u r i n g t h e f a l l r e h a b i l i t a t i o n p r o c e e d e d , a n d r e n e w e d c r a c k i n g was n o t o b s e r v e d u n t i l m i d A p r i l 1 9 8 8 . A d d i t i o n a l d r a i n a g e a n d p r i s m s w e r e p l a c e d o n t h e w a l l a s t h e summer p r o g r e s s e d . J u n e 1 8 t h b r o u g h t a h e a v y r a i n f a l l , o f 1 8 . 6 mm, a n d movement r a t e s w e n t a s h i g h a s 14 m m / d a y . T h i s was f o l l o w e d b y a d r y p e r i o d , a n d a s u b s e q u e n t r e d u c t i o n i n movement r a t e s , a maximum o f 3 m m / d a y . A n o t h e r h e a v y r a i n f a l l d e l i v e r e d 4 3 . 4 mm o f p r e c i p i t a t i o n a n d movement r a t e s c l i m b e d t o 7 mm/day a n d s t a y e d t h e r e . By S e p t e m b e r 1 s t t h e t h r e e week a v e r a g e , f o r movement r a t e s , was g r e a t e r t h a n 4 m m / d a y , s o s u r v e y i n g was b e i n g d o n e o n c e e v e r y 72 h o u r s . T h e e x t e n s o m e t e r s t a t i o n o n t h e 1725 m b e r m was i n s t a l l e d , o n S e p t e m b e r 6 t h , s o some i n d i c a t i o n o f movement c o u l d b e d e t e r m i n e d when t h e w e a t h e r p r e v e n t e d a s u r v e y b e i n g d o n e . By S e p t e m b e r 1 2 t h t h e movement r a t e s w e r e u p t o 10 mm/day a n d 15 mm/day b y t h e 1 5 t h . Due t o t h e h i g h movement r a t e s s u r v e y s w e r e b e i n g d o n e e v e r y d a y , w e a t h e r p e r m i t t i n g . On t h e 1 6 t h t h e a r e a was c o v e r e d i n f o g , b u t v i s u a l i n s p e c t i o n s c o n f i r m e d c r a c k s w e r e w i d e n i n g a n d t h e e x t e n s o m e t e r r e a d i n g i n d i c a t e d movement r a t e s w e r e up t o 2 5 m m / d a y , a n d a l l p e r s o n n e l a n d e q u i p m e n t w e r e r e m o v e d . On t h e 1 7 t h t h e s u r v e y i n d i c a t e d movement r a t e s w e r e u p t o 40 mm/day a n d t h a t f a i l u r e was i m m i n e n t . On t h e m o r n i n g o f t h e 1 8 t h t h e w a l l f a i l e d . 125 1 1 . 4 CAUSES OF THE T O P P L I N G F A I L U R E T h e c a u s e s a r e no d i f f e r e n t f r o m t h e o n e s r e p o r t e d f o r t h e J u l y 2 7 , 1987 f a i l u r e . T h e s e i n c l u d e i n a p p r o p r i a t e w a l l d e s i g n , b l a s t i n g damage t o t h e w a l l a n d g r o u n d w a t e r . T h e 1988 f a i l u r e was a l s o v e r y s u d d e n . O b s e r v a t i o n s made a f t e r t h e f a i l u r e show t h a t t h e o n c e v e r t i c a l b e d s w e r e now l y i n g h o r i z o n t a l . T h i s w o u l d i m p l y a l o t o f e n e r g y was s u d d e n l y r e l e a s e d . U s u a l l y b e d s w i l l r o t a t e o n l y 4 5 ° f r o m t h e i r o r i g i n a l p o s i t i o n . T h i s t i m e h o w e v e r , a r a i n f a l l d i d n o t a c c o m p a n y t h e f a i l u r e , a l t h o u g h g r o u n d w a t e r d i d h a v e a n e f f e c t a s shown i n t h e m o n i t o r i n g d a t a . T h e l i t h o l o g y i s f e l t t o b e r e s p o n s i b l e f o r t h e s u d d e n n e s s . T h e f a c e o f t h e 1690 b e n c h c o n s i s t e d o f 3 m t h i c k c o m p e t e n t s a n d s t o n e , w h i c h i s b e l i e v e d t o h a v e a c t e d l i k e a b u t t r e s s ( F i g u r e 3 6 ) . O v e r t i m e h i g h e n o u g h s t r e s s e s w e r e g e n e r a t e d w h i c h w e r e a b l e t o f r a c t u r e t h e s a n d s t o n e a n d c a u s e f a i l u r e o f t h e s l o p e . S u r v e y d a t a i n d i c a t e s w a t e r c e r t a i n l y c o n t r i b u t e d t o g e n e r a t i n g t h o s e s t r e s s e s , a n d d r a i n a g e may h a v e b e e n i n s t a l l e d t o o l a t e . T h e o v e r a l l w a l l a n g l e may h a v e b e e n t o o s t e e p , b u t t h i s c a n n o t b e d e t e r m i n e d c o n c l u s i v e l y . Q u a n t i f y i n g t h e damage c a u s e d b y b l a s t i n g a n d w a t e r p r e s s u r e s i s n o t p o s s i b l e . A l t h o u g h p r e s h e a r b l a s t i n g was u s e d o n t h e l o w e r b e n c h e s damage s t i l l o c c u r r e d . T h i s d e c r e a s e d t h e j o i n t s p a c i n g w h i c h c r e a t e d g r e a t e r i n s t a b i l i t y . 126 1 1 . 5 R E M E D I A L MEASURES T A K E N R e m e d i a l m e a s u r e s c o n s i s t e d o n l y o f c o m p l e t i n g t h e a r t i f i c i a l s u p p o r t p r o g r a m . T h e e f f e c t i v e s t r i p p i n g r a t i o t o c o m p l e t e l y r e h a b i l i t a t e t h e f a i l u r e was 1 1 . 7 : 1 , w h i c h i s n o t e c o n o m i c a l . R e m o v i n g t h e f a i l u r e m a t e r i a l may h a v e i n i t i a t e d a n o t h e r f a i l u r e , r e s u l t i n g i n t h e l o s s o f t h e c o a l . E a n d J seams w e r e r e m o v e d e n t i r e l y down t o t h e 1600 m e l e v a t i o n , a n d e a s t o f t h e s l i d e t h e w a s t e r o c k was r e m o v e d down t o t h e same e l e v a t i o n . T h e d r a g l i n e was t h e n b r o u g h t i n , a n d t h e r e s u l t s w e r e v e r y g o o d . T h e t r e n c h was e x c a v a t e d t o a d e p t h o f a t l e a s t 2 3 m, a n d i n some a r e a s e v e n d e e p e r b e f o r e t h e w a l l s o f t h e t r e n c h t h r e a t e n e d t o f a i l . 127 12 . ANALYSIS OF THE MARMOT VERTICAL LIMB FAILURE The d i s t i n c t element method, which i s r e l a t i v e l y new, was used to analyze the f a i l u r e . The concept was f i r s t proposed i n 1971 by Peter Cundall, and since that time the method has undergone constant revisions. In 1980 Cundall documented the computer program UDEC (Universal D i s t i n c t Element Code), which has been further developed and documented by Cundall and Hart i n 1985. The l a t e s t developments have been made by Lemos. The program has been compared to the Limiting Equilibrium Analysis, proposed by Goodman and Bray (1976), but most of the work done using UDEC has been i n other areas, such as tunnel design or flow through a fractured medium. 12.1 INTRODUCTION AND BACKGROUND MATERIAL The d i s t i n c t element method i s a recognized discontinuum modelling approach used to model a j o i n t e d media subjected to q u a s i - s t a t i c or dynamic loading. Three d i s t i n c t features make the d i s t i n c t element method i d e a l for discontinuum modelling: 1) The medium i s simulated as an assemblage of blocks which in t e r a c t though corner and edge contacts. 2) D i s c o n t i n u i t i e s are regarded as boundary interactions between these blocks; discontinuity behaviour i s prescribed f o r these interactions. 128 3) The method u t i l i z e s an e x p l i c i t timestepping algorithm which allows large displacements and rotations and general non-linear c o n s t i t u t i v e behaviour f o r both the matrix and d i s c o n t i n u i t i e s (Itasca Consulting Group, 1988). The UDEC program, which i s a two dimensional version of the d i s t i n c t element method, i s meant to simulate the primary features of a fractured system. Features included i n the code are variable rock deformability, complex j o i n t structures, non-linear i n e l a s t i c j o i n t behaviour, p l a s t i c behaviour of inta c t rock, f l u i d flow i n j o i n t s and f a r f i e l d s t a t i c or dynamic boundary conditions (Itasca Consulting Group, 1988). The program can be used to determine the f l u i d flow through a jointed rock mass beneath a dam, to analyze f a i l u r e at the grout/reinforcing interface, to determine tunnel l i n i n g required and for thermal-mechanical modelling. Some of i t s special features include: a) Automatic tunnel generator. b) Structural element l o g i c to simulate reinforcement and tunnel l i n i n g . c) Gravity loading. d) Non-reflecting and f r e e - f i e l d boundary conditions for dynamic analyses. e) Transient heat flow and thermally-induced stresses. 129 f) Automatic damping and timestep determination. g) Programmed error messages(Itasca Consulting Group, 1988) . The UDEC version used to analyze the f a i l u r e was written i n FORTRAN77 and run on a 386/387 machine with 4 Mb of RAM memory. Although the machine has a clock speed of 2 5 MHz the running time for a simulation was lengthy. The running time was estimated to take 11 days to simulate 1 m of displacement. 12.2 THEORY OF UDEC (UNIVERSAL DISTINCT ELEMENT CODE) The d i s t i n c t element method consists of taking a domain and breaking i t up into blocks, which allows the blocks or elements to be defined by the spacing and orientations of the major d i s c o n t i n u i t i e s i n a rock mass. The blocks are then able to disconnect from adjacent blocks, and the separation pattern i s controlled by the d i s c o n t i n u i t i e s . The method uses continuum theory, force displacement laws and motion laws. Continuum theory s p e c i f i e s how the in d i v i d u a l blocks w i l l behave i n t e r n a l l y when subjected to external forces. I f the simulation uses f u l l y deformable blocks rather than r i g i d blocks the in d i v i d u a l blocks are d i s c r e t i z e d into a f i n i t e difference g r i d and continuum theory i s used. Discontinuum theory i s then used to model how the blocks w i l l behave i n r e l a t i o n to each other. The 130 force displacement laws then specify the forces between those blocks, while the motion laws control the motion of each block due to the unbalanced forces acting on the block. The method i s based on e x p l i c i t formulation, which means that a l l quantities on one side of the equation are known, and t h i s equation i s then evaluated to produce the r e s u l t f o r the other side of the equation. For the numerical model to be stable the e x p l i c i t formulation, which i s dependent on the fact that i t takes a f i n i t e time for information to propagate through a system of blocks, must have a small enough time step to allow information to pass between neighbouring blocks at a speed le s s than p h y s i c a l l y possible. In other words, i f the time step i s too large the blocks w i l l move too f a r and the r e s u l t s w i l l not come to equilibrium. The time step should be small enough to allow only a small degree of movement, and then to acquire larger movements the simulation i s run through a large number of cycles. The user controls the time step by the s i z e of blocks and the value of the s t i f f n e s s used. The larger the block or the lower the s t i f f n e s s value the larger the time step w i l l be. Large time steps are preferred to reduce computer time. UDEC can have either r i g i d or deformable blocks. For the analysis of the toppling f a i l u r e i n the V e r t i c a l Limb, r i g i d blocks were used for two reasons. The j o i n t spacing was very small therefore the i n d i v i d u a l blocks were small, 131 which decreased the time step. These small blocks also meant a large number of blocks were generated, so the time for one complete cycle increased. The second reason was the slope appeared very blocky and r i g i d looking, and the f a i l u r e material s i t t i n g on the p i t f l o o r was c e r t a i n l y blocky. Some of the blocks were the si z e of a small room. The r i g i d formulation represents the rock mass as a set of d i s t i n c t blocks which do not change t h e i r geometry as a r e s u l t of applied forces i . e . , i n d i v i d u a l blocks are not d i s c r e t i z e d into a f i n i t e difference g r i d . The method can be used for systems where the material e l a s t i c properties can be ignored. Conditions require a low stress environment and/or where the material possesses high strength and low deformability (Itasca Consulting Group, 1988). 12.3 PARAMETERS USED IN THE STUDY A l i m i t e d amount of data was required to run the simulation. The only values needed were Poisson's r a t i o , Young's modulus, shear s t i f f n e s s , normal s t i f f n e s s , shear strength, s p e c i f i c weight and the geometry of the problem. Shear strength and s p e c i f i c weight came from the rock t e s t i n g done by Golder Associates (Stacey, 1981) , and the other values came out of the l i t e r a t u r e . The shear strength values have been increased over the base f r i c t i o n angle by 5° for the shale and 6° f o r the sandstone due to j o i n t roughness. For the Gates, which i s a poor sandstone the 132 following parameters were used: Shear strength = 35 degrees Poisson's r a t i o = .18 Young's modulus =41 GPa Shear s t i f f n e s s = 20,000 MPa/m Normal s t i f f n e s s = 40,000 MPa/m Spe c i f i c weight = .00264 Kg/m3 For the Hulcross, which i s a shale the following parameters were used: Shear strength = 32 degrees Poisson's r a t i o = .21 Young's modulus =20 GPa Shear s t i f f n e s s = 20,000 MPa/m Normal s t i f f n e s s = 40,000 MPa/m Sp e c i f i c weight = .00264 Kg/m3 From i n i t i a l t e s t runs the parameter which had the most e f f e c t on s t a b i l i t y was shear strength. The l i t e r a t u r e suggested Poisson's r a t i o could be anywhere between .15 and .35 f o r a t y p i c a l rock, so a lower value was chosen f o r the sandstone and a higher value f o r the Hulcross shale. Young's modulus was taken from the l i t e r a t u r e and average values were chosen. The normal and shear s t i f f n e s s values came out of the UDEC manual. Due to the large time requirements needed to run a simulation, only the shear strength parameter was changed. Changing the shear strength does have a great e f f e c t on the simulation, and t h i s can be used to calcu l a t e a factor of safety. I f the simulation suggests the system i s stable using the current parameters the shear strength can be reduced u n t i l the wall begins to f a i l . The factor of safety i s then equal to the actual 133 f r i c t i o n angle divided by the f r i c t i o n angle to cause f a i l u r e . 12.4 SIMULATIONS RUN Eleven simulations were run and three f a i l e d . The other eight came to equilibrium and d i d not f a i l . The simulations were a l l run using the same parameters i n i t i a l l y , so the difference was geometry. To t r y and model what e x i s t s i n the p i t the j o i n t spacing was i n t e n s i f i e d near the surface and reduced at depth. The greater i n t e n s i t y of j o i n t s near the surface was to model the b l a s t damage. At the toe of the wall large j o i n t spacings were used to simulate the a r t i f i c i a l support that had been i n s t a l l e d . Figure 42 shows how the wall was divided before any material was excavated, Figure 43 shows the wall a f t e r excavation. The simulations were a l l completed i n the same manner. F i r s t the system was set up as shown i n Figure 42 and g r a v i t y was applied u n t i l equilibrium was attained. Equilibrium was determined from graphs of X-velocity vs time, Y-velocity vs time, X-displacement vs time and Y-displacement vs time. Figures 44 and 45 show v e l o c i t y vs time and displacement vs time f o r a simulation that did not f a i l , but came to equilibrium. Once equilibrium was attained the benches were excavated i n three stages, 1725 m to 1690 m, 1690 m to 1640 m and 1640 m to 1610 m. For simulations which returned to equilibrium, a f t e r the l a s t 134 5 ft 3 Of OJ ?? Uj u) 2 ° S 10 CO V V V O V V 9 o « ii i iT. O o X U B O O " O B » >• <D (U ° u i 7 - • u • t . o ffl CD O O 9 U ^ M « ^ ^ 135 1 3 6 137 138 bench had been removed the program was stopped. For the three that d i d not immediately return to equilibrium the simulation was run for a longer time period to ensure that f a i l u r e was indeed occurring. To determine what type of f a i l u r e was occurring blocks with t h e i r respective v e l o c i t y vectors were plotted (Figure 46). The o r i e n t a t i o n and si z e d i s t r i b u t i o n of the v e l o c i t y vectors are t y p i c a l of what would be expected for a toppling f a i l u r e . Most of the movement i s i n the horizontal, which the monitoring data supports, and the amount of movement decreases with depth. The motion of the columns i s a combination of s l i d i n g and toppling. Using the above method the d i f f e r e n t geometries were run. The seven geometries can be seen i n Figure 43, Figures 47 to 52. Common to a l l geometries i s an underlying material with a bedding j o i n t spacing of 10 m, and a bedding j o i n t spacing near the surface equal to 2 m. The value of 10 m was chosen bearing i n mind bedding j o i n t spacing reported before bl a s t i n g . The value of 2 m was chosen for the Gates although, the r e a l spacing i s 1.5 m. The higher value was used to keep the computer running times reasonable. The Gates was assumed to control s t a b i l i t y and a 2 m j o i n t spacing i n the Hulcross was considered reasonable. Actual j o i n t spacing i n the Hulcross varies from 10 cm to 50 cm. The material boundary between Gates 139 140 141 142 143 144 145 146 and Hulcross was chosen as a l i n e dipping 85° into the wall that begins at the crest of the 1690 bench. One group with a block height of 6 m, Figures 43, 47, 48 and 49, have varying step heights of zero, 1, 2 and 3 m respectively. Figures 50, 51 and 52 comprise another group, with a block height of 10 m, and step heights of zero, 2.5 and 5 m respectively. Table 8 outlines the r e s u l t s of the simulations. Table 8 Summary of simulations using UDEC. BLOCK HEIGHT (m) STEP HEIGHT (m) END RESULT 6 6 6 6 1 2 3 Zero F a i l e d F a i l e d Stable Stable 10 10 10 Zero 2.5 5 F a i l e d Stable Stable 147 Appendixes I to O show a l l the geometries and the re s u l t s of the simulations. The simulation with a 2 x 6 m block and a zero step was run the longest and Figures 53, 54, 55 and 56 show the v e l o c i t y graphs at two d i f f e r e n t times. Figures 53 and 54 are plo t s of X and Y v e l o c i t y vs machine time just a f t e r the p i t was excavated. Neither have returned to equilibrium. The downward plunges of the curve on Figure 53 are due to the excavation of the p i t i n three stages. Figures 55 and 56 are the plo t s a f t e r 66000 cycles and show the t y p i c a l pattern of a slope that i s f a i l i n g . I t i s not known why t h i s pattern occurs but i t does represent f a i l u r e . 148 cn uj DC U X u z Hi OD o 0 1 UJ X H I-< UJ X u UJ > X o o in in o in ni o o (U w s w 2 E u ni i * in r ni i nj I i i ( s /m) A i i o o a a A x i (0 i •o c cu 01 in o i a UJ u to a c n a ni urn u 01 A I-I to o l-l to u a 6i V c u o a a a o o o £ f-i 0) o V a to m o 01 CM (O CD T1 O x. 1 *- %-in s UJ o O o i-» \ u 01 * 01 >> > u u m i c 3 a. a a Figure 53 Marmot V e r t i c a l Limb: Xvel vs Machine Time at the 1720m bench crest. Cycles = 13000 149 Figure 54 Marmot V e r t i c a l Limb: Yvel vs Machine Time at the 1720m bench crest. Cycles = 13000 150 UI LU (C U I CJ z LU m E O CU UJ I LU LU Z M X u < X _ l LU > X LU > a x tr < x XI a to m ni cu cvi o ni w s cu I X in i o I CVI I cu I to I i I in ( s / u i ) AiiocaaA x 8 T3 C ai Ui cu T o l a UJ u o a c cu X I a rt rt 1 E 3 Sc A »—I (tl rt a CJ ca c *-i •rl a a a o *-* o o x: 4-1 at a V rt a CD CO L . •> 01 CO CVI CD to VI \ o 1 *- %-in a U i O o o ri to \ U • cu > > 4 J u 1 rt c Dep Figure 55 Marmot V e r t i c a l Limb: Xvel vs Machine Time at the 1720m bench Crest. Cycles = 66000. 151 X o (V! I i n i I 10 I (0 I (s/ui) AII0O73A A • O c 01 O l 01 i n o i eg U l u a c cn 11 i n 1 o 3 to A CO tu a I-I T u a a 4J JZ *H to a a o o o c at o V ^1 o CD to c a 01 to m CD CD o i %-i n o Ul o o o I-* CD u CO n i > > ± 1 u on I c DBP Figure 56 Marmot V e r t i c a l Limb: Yvel vs Machine Time at the 1720m bench crest. Cycles = 66000. 152 12.5 CONCLUSIONS AND RECOMMENDATIONS FOR FURTHER WORK The highest r e a l i s t i c f r i c t i o n angle was used i n the analysis but the wall s t i l l f a i l e d . The geometry or structure has an important impact on the s t a b i l i t y of the slope (Figure 57). As the step gets higher the chances of f a i l u r e are reduced. I f two blocks are side by side and both begin to topple, movement w i l l occur most e a s i l y i f the base of the blocks are able to s l i d e forward. This w i l l occur when the angle of the stepped base f a i l u r e plane i s less than the o v e r a l l p i t wall angle. For the cases which did not go to f a i l u r e the f r i c t i o n angle was reduced to 27 degrees for the Hulcross and 29 degrees for the Gates. S t i l l the simulation would not go to f a i l u r e . One important assumption made for a l l the simulations was that the j o i n t cohesion was zero, the worst case scenario. The assumption was based on the fact that high pressured gases had opened up the j o i n t s and bedding j o i n t s . The major disadvantage of t h i s method and program i s the time required to set up the problem, f i n d the best parameters to represent rock mass and run the simulation. Although a 386/387 computer with a 4 Mb of memory i s not a common un i t the price i s coming down, and i n future they should be commonplace. Another disadvantage i s the r e s t r i c t i o n on the number of blocks. 153 Ul 4 (D Ol O rt o H i iQ (D O (D rt H-(D to 0) 3 P. 0> H P> (D rt (D m c: tn ID CHART SHOWING GEOMETRIES AMD PARAMETERS USED SIMULATION BEDDING JOINT SPACING JOINT SPfiCING STEP HEIGHT RNGLE OF BHSHL PLANE §HULCROSS GATES COMMENTS 1 2 6 0.0 m. 5.0 DEGREES 32 35 FAILED 2 2 6 1.0 m. 31.7 DEGREES 32 35 FAILED 3 2 6 2.0 m 50.0 DEGREES 32 35 STABLE 4 2 6 2.0 m 50.0 DEGREES 27 29 STABLE 5 2 6 3.0 m 61.3 DEGREES 32 35 STABLE 6 2 6 3.0 m 61.3 DEGREES 27 29 STABLE 7 2 10 0.0 m 5.0 DEGREES 32 35 FAILED 8 2 10 2.5 m 56.3 DEGREES 32 35 STABLE 9 2 10 2.5 m 56.3 DEGREES 27 29 STABLE 10 2 10 5.0 m 73.2 DEGREES 32 35 STABLE 11 2 10 5.0 m 73.2 DEGREES 27 29 STABLE The more blocks i n the domain the longer the running time. More memory can be added to increase the number of blocks, but the speed of the computer i s the l i m i t i n g factor. The main advantages of using a d i s t i n c t element code over other methods, such as the Limiting Equilibrium Analysis are a more r e a l i s t i c analysis can be done, a more r e a l i s t i c j o i n t pattern determined from s t r u c t u r a l data can be modeled, and time i s incorporated into the model, so the stress d i s t r i b u t i o n can be changed with time. The stress d i s t r i b u t i o n i n t h i s analysis was changed as the various stages of excavation took place. The program, because i t moves through time steps, i s dynamic rather than s t a t i c , and contact between blocks can be edge to edge or corner to edge, which i s more r e a l i s t i c . The advantages of UDEC over a f i n i t e element code are larger possible displacements, rotation i s allowed and the rock mass does not have to be treated as a continuum. Other general advantages o f f e r a r i g i d analysis with few parameters required. UDEC finds the f a i l u r e plane rather than assuming one and UDEC determines the type of f a i l u r e . Recommendations for future work would be to t e s t the s e n s i t i v i t y of each parameter used, to better understand the e f f e c t of structure on s t a b i l i t y , and to create design charts for toppling f a i l u r e s using the UDEC program. Structure controls the type of f a i l u r e , but whether the slope w i l l f a i l i s also a function of the geologic structure 155 and f r i c t i o n angle. Different geometries should be experimented with to determine the s e n s i t i v i t y of p i t w a l l s t a b i l i t y to step height, block width and height. The UDEC program i s large and has many d i f f e r e n t uses. The next natural progression would be to t r y running toppling simulations using f u l l y deformable blocks. Simple techniques are available to analyze block topple f a i l u r e s , but to analyze block f l e x u r a l topples a D i s t i n c t Element Code would have to be used. 156 13. SUMMARY AND CONCLUSIONS The two toppling f a i l u r e s occurred due to inappropriate wall design, poor b l a s t i n g practices and transient water pressures i n the wall. Fortunately these problems can be avoided i n the future i f the lessons learned i n the V e r t i c a l Limb are not forgotten. Although the f a i l u r e s were unfortunate the V e r t i c a l Limb has reported some success. The mine and monitor method proved to be very good and gave p r i o r warning of when the f a i l u r e s would occur. The suggestion to sub coal beneath the planned p i t bottom using a dragline was fea s i b l e and the r e s u l t s were excellent. F i n a l l y , UDEC was shown to be a useful t o o l i n gaining a greater understanding of toppling f a i l u r e s . Future wall designs that incorporate the Hulcross should be r e s t r i c t e d to maximum bench heights of 15 m, and in the Gates the maximum bench height should be 30 m (Stewart, 1982, 1983, 1985(a)). These guidelines are prim a r i l y based on experience and w i l l only prevent bench scale toppling f a i l u r e s . To design a multi-bench wall with steeply dipping stratigraphy further analysis would have to be done. This could be accomplished using UDEC. Unfortunately the time required to do the analysis using UDEC would be considerable. Structure plays a very important part i n the o v e r a l l s t a b i l i t y of a toppling f a i l u r e . Therefore a good understanding of the structure and rock properties i s required i f the simulation i s to be 157 representative of conditions i n the f i e l d . UDEC i s a design t o o l which helps l i m i t the choice of wall design, but experience s t i l l provides the best answers. The lessons learned i n the V e r t i c a l Limb w i l l help when mining i n si m i l a r conditions elsewhere i n the mine. Blasting damage was a problem i n the V e r t i c a l Limb and w i l l continue to be so unless current b l a s t i n g practices are modified. The b l a s t i n g i n the V e r t i c a l Limb increased the v e r t i c a l j o i n t spacing, due to high gas pressures taking advantage of inherent weaknesses along the bedding planes. This had the e f f e c t of increasing the i n d i v i d u a l blocks height to width r a t i o , which for a rock mass prone to toppling i s detrimental. To keep the walls as steep as possible research must be done to determine the best b l a s t i n g patterns and techniques for the d i f f e r e n t rock types. Immediate improvements would be to use smaller diameter holes, reduce the spacing and the explosive charge i n the preshear holes, and to i n s t a l l delays between buffer holes. Research would take the form of monitoring the peak p a r t i c l e v e l o c i t i e s getting into the wall under the present conditions, and then determining how the various b l a s t i n g patterns and d i f f e r e n t loading conditions e f f e c t the v e l o c i t i e s . The benefit of t h i s research w i l l be applicable to a l l areas of the p i t . 158 Although the groundwater table i s approximately at p i t bottom, 1610 m, percolating surface runoff i n i t i a t e d the July 27th, 1987 f a i l u r e and d e f i n i t e l y contributed to the September 18th, 1988 f a i l u r e . P i t wall drainage has to be i n s t a l l e d as the p i t i s excavated to prevent movement from occurring, otherwise the shear strength along the j o i n t s i s reduced. Attempting to drain v e r t i c a l stratigraphy that has clay layers present i s also d i f f i c u l t . Pockets of water can get trapped, so to increase the p r o b a b i l i t y of h i t t i n g these pockets the density of drains must be increased. UDEC i s a useful program, and w i l l be used more often i n the future as f a s t e r machines become more commonplace. At present the simulation s t i l l has to be s i m p l i f i e d , so the running times are reasonable. Even then to run a simulation requires an inordinate amount of time which means that running v a r i a t i o n s i s often not possible. Using a mainframe would c e r t a i n l y speed up running times, but because many runs are required to f i n d acceptable parameters t h i s could be very expensive. The r e a l strength of UDEC i s that a j o i n t e d rock mass can be modelled and i t s behaviour studied under s t a t i c and dynamic conditions. The r e s u l t s from the d i f f e r e n t simulations, show how important geologic structure i s to s t a b i l i t y i n rock masses prone to toppling. I f the steps along the basal f a i l u r e plane are too b i g the whole system locks up because the stepped basal f a i l u r e plane i s dipping steeper than the o v e r a l l wall angle. This means the 159 toe area i s unable to move and therefore blocks higher up cannot rotate or s l i d e forward along the basal plane. Small steps develop a shallower stepped basal f a i l u r e plane, which can daylight. The toe area can now move enough that blocks higher up can s l i d e forward and rotate r e s u l t i n g i n f a i l u r e . Toppling f a i l u r e s are not c l e a r l y understood and few tools are a v a i l a b l e to analyze them. UDEC i s ideal for modelling a j o i n t e d rock mass and models a toppling f a i l u r e very well. The next step would be to generate design charts f o r d i f f e r e n t geometries and parameters using UDEC. The suggestion to sub coal below the planned p i t bottom turned out to be f e a s i b l e . Although the dragline during the i n i t i a l t e s t i n g period performed poorly i t worked well a f t e r the overhaul. The adjustments to the dragline consisted of increasing the boom length and bucket weight and overhauling the machinery. The plan was to excavate blasted coal to a depth of 23 m, but when E an J seams were mined a depth of up to 28 m was attained. At t h i s point the trench wall caved and buried the bucket f o r three days. The recommendation would be to have a spare bucket available, because timing i s c r i t i c a l . Once the coal has been removed the trench was back f i l l e d to increase s t a b i l i t y . I n i t i a l l y the trench was not back f i l l e d immediately a f t e r excavation and the o v e r a l l wall movement rates began to increase. The longer the trench wall i s unsupported the greater the 160 p r o b a b i l i t y of the trench wall f a i l i n g and movement rates increasing. The V e r t i c a l Limb was a very good example of how well a mine and monitor method can work. The monitoring was superb and everyone concerned had confidence i n the r e s u l t s . The movement rates were small yet accurate readings were possible. Predicting when the f a i l u r e was going to occur was f e a s i b l e . Coal recovery was maximized and a minimal quantity of coal l o s t . 161 14. BIBLIOGRAPHY B e l l , F.G. ENGINEERING PROPERTIES OF SOILS AND ROCKS. Toronto, Ont: Butterworths & Co., 1981. Brawner, CO., Stacey, P.F. and Stark, R. A SUCCESSFUL APPLICATION OF MINING WITH PITWALL MOVEMENT. Proc. Annual Western Meeting, Canadian I n s t i t u t e of Mining, Edmonton, Alberta, 1975 Burridge, C. ENHANCEMENT OF SURVEY PROCEDURES FOR MONITORING MARMOT VERTICAL LIMB. Internal Report, Quintette Coal Ltd., Tumbler Ridge, B.C., 1988. Carmichael, Scott M.M. SEDIMENTOLOGY OF THE LOWER CRETACEOUS GATES AND MOOSEBAR FORMATIONS, NORTHEAST COALFIELDS, BRITISH COLUMBIA. 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Manual, Minneapolis, Minnesota: Itasca Group Inc, 1988. Kennedy, B.A., Niermeyer, K.E. and Fahm, B.A. A MAJOR SLOPE FAILURE AT THE CHUQUICAMATA MINE, CHILE. Mining Engineering. A.I.M.E., Vol. 12, No. 12, 1969, page 60. 163 Pelley, M.H. 1983 QUINTETTE GEOLOGICAL REPORT. Government Report, Quintette Coal Ltd., Tumbler Ridge, B.C., 1985. Piteau, D.R. ROCK SLOPE ENGINEERING: PART F BLASTING FOR ROCK SLOPES AND RELATED EXCAVATION CONSIDERATIONS. Piteau & Associates, Vancouver, B.C. 1979. Piteau, D.R., Stewart, A.F. and Martin, D.C. DESIGN EXAMPLES OF OPEN PIT SLOPES SUSCEPTIBLE TO TOPPLING. Internal Report, Piteau & Associates, Vancouver, B.C., 1982. Quintette Coal Ltd. 1982 QUINTETTE GEOLOGICAL REPORT. Government Report, Quintette Coal Ltd., Tumbler Ridge, B.C., 1983. Reid, G. and Stewart, D. A LARGE TOPPLING FAILURE AT AFTON Proc. of the International Symposium on Geotechnical S t a b i l i t y i n Surface Mining, Calgary, Alberta, 1986. Sperling, A. SLOPE STABILITY AND GROUNDWATER HYDROLOGY RESEARCH FOR PITWALL DESIGN AT EQUITY SILVER MINES LTD. HOUSTON, BRITISH COLUMBIA. Unpublished M.A.Sc th e s i s , Department of Mining and Mineral Process Engineering, University of B r i t i s h Columbia, 1985. Stacey, P.F. REPORT TO DENISON MINES LTD. ON GEOTECHNICAL ASPECTS OF THE SHERIFF PIT. Internal Report by Golder Associates, Vancouver, B.C., 1981. Stewart, A.F. TOPPING ANALYSES FOR SHERIFF PIT. Internal Report by Piteau & Associates, Vancouver, B.C., 1982. Stewart, A.F. SLOPE STABILITY CONCERNS IN THE MARMOT PIT. Internal Report by Piteau & Associates, Vancouver, B.C., 1983. Stewart, A.F., Trenholme, B.S. and Hawley, P.M. GEOTECHNICAL INVESTIGATION AND DESIGN GUIDELINES FOR FOOTWALL SLOPES IN THE MESA PIT. Internal Report by Piteau & Associates, Vancouver, B.C., 1985(A). Stewart, A.F. POTENTIAL TOPPLING FAILURES ON MARMOT HIGHWALL. Internal Report by Piteau & Associates, Vancouver, B.C., 1985(B) Stewart, A.F. and Hawley, P.M. STABILITY CONCERNS IN THE MARMOT PIT. Internal Report by Piteau St Associates, Vancouver, B.C., 1985(C). 164 Stewart, A.F. and Hawley, P.M. GENERAL CONCERNS FOR MARMOT AND MESA PIT AREAS. Internal Report by Piteau & Associates, Vancouver, B.C., 1986(A). Stott, D.F. LOWER CRETACEOUS BULLHEAD AND FORT ST. JOHN GROUPS BETWEEN SMOKY AND PEACE RIVERS, ROCKY MOUNTAIN FOOTHILLS, ALBERTA AND BRITISH COLUMBIA. Geological Survey B u l l e t i n 152, 1968, 279p. Stott, D.F. LOWER CRETACEOUS COAL MEASURES OF THE FOOTHILLS OF WEST-CENTRAL ALBERTA AND NORTH EASTERN BRITISH COLUMBIA. Canadian Mining and Met a l l u r g i c a l B u l l e t i n , V o l . 67, 1974, page 87-101. Turchaninov, I.A., I o f i s , M.A. and Kasparyan, E.V. PRINCIPLES OF ROCK MECHANICS. Trans. W.A. Hustrulid. R o c k v i l l e , Maryland: Terraspace Inc., 1979. 165 APPENDIX A Approximate rock strength c l a s s i f i c a t i o n . 166 Approximate Rock Strength C l a s s i f i c a t i o n (Hoek and Bray, 1981) No. Daaeription Uniaxial ccipretaivt strength lb/in1 kg/cm1 MPa Example* SI VERY SOFT S O I L - e a s i l y m o u l d e d w i t h f i n g e r s , shows d i s t i n c t h e a l m a r k s . <5 <0.li <0.0li S2 SOFT SOIL - m o u l d s w i t h s t r o n g p r e s s u r e f r o m f i n g e r s , shows f a i n t h e e l m a r k s . 5-10 0.<«-0.8 0 .0U-0 .08 S3 FIRM SOIL - v e r y d i f f i c u l t t o mould w i t h f i n g e r s , i n d e n t e d w i t h f i n g e r n a i l , d i f f i c u l t to c u t wi t h h a n d s p a d e . 10-20 0.8-1.5 0.08-0.15 Sk S T I F F SOIL - c a n n o t be m o u l d e d w i t h f i n g e r s , c a n n o t be c u t w i t h hand s p a d e , r e q u i r e s hand p i c k i n g f o r e x c a v a t i o n . 20-80 1 . 5 - 6 . 0 0 .15 -0 .60 S5 VERY S T I F F SOIL - v e r y t o u g h . d i f f i c u l t t o move w i t h hand p i c k , p n e u m a t i c s p a d e r e q u i r e d f o r e x c a v a t i o n . 80 - 1 5 0 6 - 1 0 0 . 6 - 1 . 0 RI VERY WEAK ROCK - c r u m b l e s u n d e r s h a r p b l o w s w i t h g e o l o g i c a l p i c k p o i n t , c a n be c u e w i t h p o c k e t k n i f e . 150-3500 10 -250 1-25. C h a l k , r o c k s a l t R2 HOOERATELY WEAK ROCK - s h a l l o w c u t s o r s c r a p i n g w i t h p o c k e t k n i f e w i t h d i f f i c u l t y , p i c k p o i n t i n d e n t s d e e p l y w i t h f i r m b l o w . 3500 -7500 2 5 0 - 5 0 0 25 - 5 0 C o a l , s c h i s t , s i l t s t o n e A3 MODERATELY STRONG ROCK • k n i f e c a n n o t be u s e d t o s c r a p e o r p e e l s u r f a c e , s h a l l o w i n d e n t a -t i o n s u n d e r f i r m b l o w f r o m p i c k p o i n t . 7500-15000 S00 - I 0 0 0 5 0 - 1 0 0 S a n d s t o n e , s l a t e , s h a l e Uk STRONG ROCK - h a n d - h e l d s a m p l e b r e a k s w i t h o n e f i r m b l o w f r o m hammer e n d o f g e o l o g i c a l p i c k . 15000-30000 1000-2000 100-200 M a r b l e , g r a n i t e , g n e i s s R5 VERY STRONG ROCK - r e q u i r e s many b l o w s f r o m g e o l o g i c a l p i c k t o b r e a k i n t a c t s a m p l e . > 30000 > 2000 > 200 Q u a r t z ! t e , d o l e r i t e , g a b b r o , b a s a l t 167 APPENDIX B Operational procedures f o r the V e r t i c a l Limb. Procedures f o r the inspection, closure and reopening of the Marmot v e r t i c a l limb. 168 QUINTETTE COAL LIMITED INSPECTION, CLOSURE AND REOPENING PROCEDURES MARMOT VERTICAL LIMB (Section 34,400 to Section 35,400) Revised August 31, 1988 INTRODUCTION The p rocedures s p e c i f i e d a re i n t e n d e d to ensure the s a f e t y of employees and equipment deployed i n the Marmot V e r t i c a l Limb between the l o c a t i o n o f Ka l T i r e and t h e e r e c t i o n s i t e . S e c t i o n 2 d e a l s w i t h the most common causes f o r c l o s u r e s and reopen ings o f the s u b p i t , o p e r a t i o n a l c o n s i d e r a t i o n s . S e c t i o n s 3 to 6 dea l w i t h c l o s u r e s and subsequent reopen ings f o r g e o t e c h n i c a l r e a s o n s , wh ich a r e , p o t e n t i a l o v e r a l l o r bench s c a l e w a l l i n s t a b i l i t y . I t i s the r e s p o n s i b i l i t y o f t he p r o d u c t i o n Genera l Foreman on s h i f t to ensure the p r o c e d u r e s i n S e c t i o n 2 t o 4 and s e c t i o n 6, i n c l u s i v e are c o m p l i e d w i t h . S e c t i o n 5 i s the r e s p o n s i b i l i t y o f t h e Manager of M in ing o r A c t i n g Manager . CLOSURES AND RE-OPENINGS FOR OPERATIONAL CONSIDERATIONS 2.1 P e r i o d i c c l o s u r e s o f the Marmot V e r t i c a l Limb w i l l o c c u r f o r such r easons as heavy r a i n f a l l , (a t t imes when the G e o t e c h n i c a l s t a f f has no t d e s i g n a t e d any c r i t i c a l a r e a s ) , poor v i s i b i l i t y , p r e v e n t a t i v e s c a l i n g , o r numerous o t h e r o p e r a t i o n a l c o n s i d e r a t i o n s . These c l o s u r e s and subsequent r e - o p e n i n g s a re a t the d e s c r e t i o n o f the P r o d u c t i o n General Foreman. A no te o f the c l o s u r e s h o u l d be made i n t he V e r t i c a l Limb l o g book , and d i s t i n g u i s h e d from c l o s u r e s prompted by the G e o t e c h n i c a l c r i t e r i a i n t h i s m a n u a l . INSPECTION FOR GEOTECNHICAL REASONS 3.1 At the beginning of every s h i f t , when men and equipment are working in the Marmot subpit, the area Production Foreman or Production General Foreman w i l l conduct a visual inspection of the p i t wa l ls , from the p i t bottom, with special attention to any areas of unusual rave l l ing or potential problem areas as may be designated by Geotechnical s ta f f . 3.2 In areas designated by Geotechnical s t a f f , a visual inspection of safety berms, bench faces and c r e s t s , and the p i t rim w i l l be conducted by the area shift -Production Foreman^or Prodiicffon General Foreman on the fol lowing schedule: - once every 24 hours 1n areas where the 3 week average prism monitor horizontal movement rate exceeds 4 mm/day. - during periods of s i g n i f i c a n t r a i n f a l l or snowraelt, the wall shal l be v isua l ly inspected in areas designated by the geotechnical s t a f f , at intervals of not greater than 12 hours from the previous inspect ion. (NOTE: A "s igni f icant r a i n f a l l " would be a moderate or heavy r a i n f a l l as out l ined in Section 3 .3 , but not of a duration to warrant c losure . ) 169 Inspection, Closure and Reopening Procedures Marmot Vertical Limb 2 3.3 A visual inspection shall be conducted at least twice per week by the Mine Geotechnical Engineer or qualified designate in areas where the 3 week average horizontal movement rate exceeds 1.5 mm/day. 3.4 It is the responsibility of the Hine Geotechnical Engineer to: - carry out the inspection defined in 2.3 - ensure that prisms (monitors) are strategically located on the wall within the area defined with particular attention to the 1660 and 1640 benches. - ensure that the frequency of measurement of movements indicated by the prisms is in accordance with the direction provided in Table 1. - provide the Production General Foreman with an interpretation (report) of the data collected and a recommendation as to what action should be taken in areas where the 3 week average prism monitor horizontal movement rate exceeds 1.5 mm/day. This report will be entered in the Vertical Limb log book. 3.5 Upon completion of his evaluation of the inspection report and/or the recommendation (report) of the Geotechnical Engineer, and based on the interpretation of prism readings, the General Foreman will make one of trie "following decisions: - to maintain normal operations.' - to immediately close the hazardous portion of the subpit. - to immediately close the entire subpit. 3.6 Before going off shift, the General Foreman shall ensure all such reports are placed in the Marmot Vertical Limb logbook maintained in his off ice. 4. G U I D E L I N E S F O R G E O T E C H N I C A L C L O S U R E The following conditions are grounds for closure: 4.1 Visual Inspection Report - indicates that: - visually detectable ground movement is occurring; - along new or previously known tension cracks - in the form of depressions developing 1n association with tension cracks that are parallel to bedding 170 Inspection, Closure and Reopening Procedures Marmot Vertical Limb 3 - an abnormal build-up of debris on a bench has occurred and there is tension crack development on the bench above. - an abnormal build-up of debris is occurring on al l benches, tension cracks and/or a depression are developing back from the pit rim. - there is excessive water flowing along a bench and i t is draining through a tension crack or soft ground on a bench (which indicates cracks below). 4.2 °rism (Monitor) Measurement Report - the recommendation of the Geotechnical Engineer 4.3 Closure Due to Rainfall: Rainfall is generally not grounds for closure; however in areas designated by  the Geotechnical staff, intense storms, rainfall events equivalent to water depths of 15 to 30 mm/day warrant implementation of a partial closure of the subpi t. Rainfall events of intensity greater than 15 mm/day occur approximately four times per year at QCL's Mesa and Wolverine pi ts . The following are recommended guidelines for estimation of rainfall which warrants closure. - in excess of 12 hours of moderate precipitation or a half hour of heavy rain where moderate and heavy rainfall is characterized by: Moderate - large droplets Rainfall - droplets are dense or concentrated in occurrence - non water-resistant clothing becomes wet and eventually soaks through to skin. - generally from lower cloud, darker skies Heavy - large droplets, frequently mixed with hailstones. Rainfall - very intense, spatially concentrated - soaks through clothing to skin in amatter of minutes - usually of short duration (less than one hour) - most often associated with thunder storms, very dark skies. 171 Inspect/cn, Closure and Reopening Procedures Marmot Vertical Limb 4 5. C L O S U R E FOR G E O T E C H N I C A L R E A S O N S 5.1 When a production General Foreman decides to either close the entire area or part of i t , he shall ensure the following actions are carried out: - immediately give instructions to withdraw fromthe area or part of i t considered unstable, ensure his instructions have been followed and then take steps to prevent persons entering thereafter. - the minimum distance of withdrawal should be equal to the height of the crest of the fai lure above the pit floor. - contact the mine Dispatcher and request that he notify the following personnel of his actions: - Shift production Foreman - Shift maintenance Foreman - Shift blasting Foreman - Manager of Mining - Superintendent of Mine Operations - Mesa/Wolverine - Superintendent of Engineering - Senior Mining Engineer - Geotechnical - Mesa/Wolverine Geotechnical Engineer - record time, date, area of closure, and time and date when above individuals notif ied, in the Marmot Vertical Limb logbook. 5.2 Priorities for withdrawal shall be: 1. Withdrawal of men, 2. Withdrawal of equipment. Where withdrawal of men is signficantly prolonged by removal of equipment, the equipment shall temporarily be left in place, until continuous visual monitoring of the problem area(s) responsible for the closure can be established. Previously abandoned equipment may be withdrawn while a monitor man maintains continuous visual monitoring anTraaTo contact with the equipment operator(s). Should the condition of the wall abruptly deteriorate, the monitor man shall immediately implement measures to ensure the safety of the operator(s). 172 Inspection, Closure and Reopening Procedures Marmot Vertical Limb 5 6. R E O P E N I N G F O R G E O T E C H N I C A L R E A S O N S 6.1 Upon notification of a partial or total closure of the area, the Manager or Acting Manager shall in the order stated: - ensure the production General Foreman has carried out his . . responsibilities stated in 4.1 - take himself or cause to be taken such action that will result in stabilization of the wall. - obtain qualified verification that the wall has stabilized and that mining may recommence in the closed area. - advise the production General Foreman on shift that the wall has stabilized, why i t is considered stable and provide him with a copy of the latest inspection and prism measurement reports. - determine when mining is to recommence and ensure all persons l isted in 4.1 are so notif ied. 173 APPENDIX C l i m b C t U r a l d a t a p l o t s f o r b e d d i n < ? i n the V e r t i c a l 174 contents of f i l e : B D N W P I T . D A T T i t l e : Bedding in the marmot V e r t i c a l Limb Data type: Planar Number of data pairs: 50 134,90 301,82 136,84 148,90 150,88 144,86 139,90 146,86 317,86 128,90 134,90 307,85 136,90 148,90 151,87 146,90 139,90 141,85 320,88 139,87 136,90 135,85 317,88 150,90 148,87 145,90 140,90 140,90 134,89 135,86 136,90 136,85 317,88 150,90 148,86 145,90 320,89 137,89 313,78 314,84 301,82 136,84 141,90 150,88 143,85 140,85 142,75 317,86 140,88 314,84 Contents of f i l e : BDNWHDY.DAT T i t l e : Bedding in the Marmot V e r t i c a l Limb Data type: Planar Number of data pairs: 4 136,86 141,89 240,86 142,83 Contents of f i l e : BDNWDUN. DAT T i t l e : Bedding for the Marmot V e r t i c a l Limb Data type : Planar Number of data pai r s : 92 121,89 133,90 305,88 289,71 309,73 319,83 131,87 319,87 126,89 133,90 140,88 139,90 305,86 131,87 308,88 117,88 137,83 143,80 140,88 325,86 320,88 316,87 140,87 142,89 127,89 144,90 159,90 355,86 150,90 330,88 142,90 344,82 145,90 328,87 133,90 140,88 139,90 305,86 142,86 145,90 143,90 326,86 145,88 132,90 315,89 324,87 327,82 328,82 133,90 145,90 136,86 146,90 143,88 322,89 320,84 319,89 324,87 325,78 325,80 136,86 325,87 320,79 320,78 323,88 146,90 327,86 139,89 320,89 326,82 327,89 326,86 324,84 325,82 329,87 322,82 321,80 315,89 318,89 327,87 143,90 321,89 137,90 320,87 141,90 143,90 320,89 324,88 327,85 325,73 323,81 322,81 318,80 175 ROSE DIAGRAM OF POLE TREND FOR ROSE DIAGRAM TO DETERMINE STRIKE OF BEDDING North H O "35 146 Data Points Single Line Shows Vector Mean Circular Mean = 53 degree(s) Angular Dev. = 38.06 Resultant = 0.117 BREAKDOWN OF lOx SECTORS: Range (deg) Number % 0 - 9 0 10- 19 0 20- 29 1 30- 39 4 40- 49 30 50- 59 39 60- 69 7 70- 79 0 80- 89 0 90- 99 0 100-109 0 110-119 0 120-129 0 130-139 0 140-149 0 150-159 1 160-169 0 170-179 0 mn ly Mttei itftnie of Total 3 Range (deg) 0 3 180-189 0 3 190-199 1 3 200-209 3 3 210-219 21 3 220-229 27 3 230-239 5 3 240-249 0 3 250-259 0 3 260-269 0 3 270-279 0 3 280-289 0 3 290-299 0 3 300-309 0 3 310-319 0 3 320-329 1 3 330-339 0 3 340-349 0 3 350-360 176 Number % of Total 0 0 1 1 0 0 8 5 15 10 37 25 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ROSE DIAGRAM OF DIP ANGLE FOR BEDDING IN THE NORTH WALL OF THE VERTICAL LIMB 0 Degrees "140 "115 "B4 "5b ,146 Data Points Single Line Shows Vector Mean Cir c u l a r Mean = 86 degree(s) Angular Dev. = 1.80 Resultant = 0.998 BREAKDOWN OF 10X SECTORS: Range (deg) Number % of Total 3 Range (deg) Number % of Total - 3 -0- 9 0 0 3 50- 59 0 0 10- 19 0 0 3 60- 69 0 0 20- 29 0 0 3 70- 79 8 5 30- 39 0 0 3 80- 90 138 95 40- 49 0 0 3 SPIOT by Daiton Software 177 CONTOUR PLOT OF POLES TO BEDDING/BEDDING JOINTS North I 146 Points LEGEND (for f i r s t 9 Intervals) m i - 1 IS 6 - 6 Contour Method : Schmidt (1925) B 2- 2 a 7- 7 counting Area : 0.010 m 3- 3 O 8- 8 Contour Interval : I X Points per 1\ Area 9 tza 4-c _ 4 • 9 - 9 Maximum Contour : 66 3 NOTE: Contour Patterns Repeat Every 9 Intervals 178 APPENDIX D Structural data and pl o t s f o r j o i n t s i n the V e r t i c a l limb. 179 contents of f i l e : J T N W D U N . D A T T i t l e : Joints in the north wall of the v e r t i c a l Limb Data type: Planar Number of data pa i r s : 32 55,89 48,80 244,21 64,74 207,45 194,47 49,85 92,19 207,45 235,26 59,72 331,19 71,64 48,21 29,57 235,85 65,54 59,82 58,85 211,28 59,82 85,11 240,20 205,17 238,88 67,64 205,17 51,90 62,78 48,80 73,33 84,27 Contents of f i l e : JTNWHDY.DAT T i t l e : Joints on north wall of V e r t i c a l Limb Data type: Planar Number of data pairs: 18 52,54 47,69 28,75 43,72 39,79 48,54 234,88 305,44 209,23 205,28 230,20 78,65 196,17 197,13 223,18 259,13 17,84 25,85 Contents Of f i l e : JTNWPIT. DAT T i t l e : Joints in the V e r t i c a l Limb Data type : Planar • Number of data pa i r s : 36 71,90 246,76 85,32 64,61 255,82 53,66 75,90 63,82 60,62 46,64 50,79 43,73 115,41 45,66 40,80 53,81 43,55 291,20 45,64 56,48 47,50 44,82 52,82 50,78 52,80 42,54 245,36 50,80 40,58 55,35 70,57 40,74 277,40 272,22 45,76 274,57 180 ROSE DIAGRAM OF DIP ANGLE FOR JOINTS IN THE NORTH WALL OF THE VERTICAL LIMB 0 Degrees "25 35 i — 2D. —I— 15 10 - I — 5 —t— Circular Mean Angular Dev. Resultant 57 degree(s) 12.23 0.909 86 Data Points Single Line Shows Vector Mean BREAKDOWN OF lOx SECTORS: Range (deg) Number % of Total 3 3 3 Range (deg) Number 0- 9 0 0 50- 59 10 10- 19 9 10 3 60- 69 10 20- 29 11 13 3 70- 79 12 30- 39 4 5 3 80- 90 23 40- 49 7 8 3 JPLOT by Dartoo software 12 12 14 27 181 ROSE DIAGRAM OF POLE TREND FOR JOINTS IN THE NORTH WALL OF THE VERTICAL LIMB North T2D 86 Data Points Single Line Shows Vector Mean C i r c u l a r Mean = 324 degree(s) Angular Dev. = 32.05 Resultant = 0.374 BREAKDOWN OF 10X SECTORS: Range (deg) Number % of T o t a l 3'Range (deg) Number % of Total 2 0- 9 1 1 3 180-189 3 3 10- 19 0 0 3 190-199 0 0 20- 29 1 1 3 200-209 1 1 30- 39 0 0 3 210-219 1 1 40- 49 0 0 3 220-229 0 0 50- 59 0 0 3 230-239 0 0 60- 69 0 0 3 240-249 1 1 70- 79 0 0 3 250-259 0 0 80- 89 0 0 3 260-269 0 0 90- 99 0 0 3 270-279 0 0 100-109 3 3 3 280-289 1 1 110-119 6 7 3 290-299 3 3 120-129 1 1 3 300-309 1 1 130-139 1 1 3 310-319 19 22 140-149 5 6 3 320-329 16 19 150-159 4 5 3 330-339 7 8 160-169 2 2 3 340-349 6 7 170-179 0 0 3 350-360 3 3 SPLOT br Dartoi Softnie 182 86 P o i n t s LEGEND ( f o r f i r s t 9 I n t e r v a l s ) ID 1- 1 B 6- 6 C o n t o u r Method: Schmidt (1925) B 2- 2 0 7 - 7 C o u n t i n g A r e a : 0.010 EB 3- 3 H 8- 8 C o n t o u r I n t e r v a l : 1\ P o i n t s per 1% A r e a ™ A ~ * • 9- 9 Maximum C o n t o u r : 17 5- 5 NOTE: Contour P a t t e r n s Repeat E v e r y 9 I n t e r v a l s 183 APPENDIX E St r u c t u r a l data and plots for f a u l t s i n the V e r t i c a l limb. 184 contents of f i l e : F L N W P I T . D A T T i t l e : Faults in the Marmot V e r t i c a l Limb Data type: Planar Number of data pai r s : 7 2 7 4 , 6 0 9 0 , 6 4 115,41 250,25 244,42 254,70 245,35 Faults In C M Haxaot v n t l u l Lime •orth EQUAL ARIA MOJKCTION rault* lt> th« nnaot v o r t i c a l Limb mm * una M m symbol 7 points o 7 Points Total 185 APPENDIX F S t r u c t u r a l data and p l o t s f o r major d i s c o n t i n u i t i e s the V e r t i c a l limb. 186 Contents of f i l e : JTl.DAT T i t l e : JOINT SET ONE NW MVL Data type: Planar Number of data p a i r s : 1 214,20 Contents of f i l e : JT2.DAT T i t l e : JOINT SET 2 NW MVL Data type: Planar Number of data p a i r s : 1 52,72 Contents of f i l e : JT3.DAT T i t l e : JOINT SET THREE Data type: Planar Number of data p a i r s : 1 87,24 Contents of f i l e : JT4.DAT T i t l e : JOINT SET FOUR Data type: Planar Number of data p a i r s : 1 289,44 MAJOR DISCONTINUITIES IN THE VERTICAL LIMB N o r t h 3-OlW T S X o A EQUAL AREA PROJECTION symbol JOINT SET ONE NW MVL JOINT SET 2 NW MVL JOINT SET THREE JOINT SET FOUR BEDDING AND BEDDING JOINT NW MVL Continued on Next Page Points Points Points Points Points • o 0 + A 188 APPENDIX G M o n i t o r i n g d a t a f o r t h e J u l y 2 7 , 1987 F a i l u r e . 189 VERTICAL LIMB MONITORING DATA STATION 172004 -ACTUAL SURVEY-DATE TIME NORTHING EASTING i !ELEVATION ! 1 — _ l i metres HORIZ : 1 VERT AZIMUTH . HORIZ mm/day 16-Jun-86 12 0 6099198.720 616211.741 ! 1723.400 : 1 a.ooo : o.ooa 27-Jun-86 12 • 6099198.700 616211.718 : 1723.410 : • 030 ; 0.010 229 2.8 08-Jul-86 12 • 6099198.600 616211.725 ! 1723.530 : 0.121 : 0.130 176 9. 1 10-Jul-86 12 • 6099198.590 616211.726 ! 1723.530 : 0.131 : 0. 130 174 5.0 21-Jul-86 12 0 6099198.590 616211.710 ! 1723.500 : 0.134 ! 0. 100 270 1.5 24-Jul-86 12 Q 6099198.590 616211.711 ! 1723.490 ! 0.133 : 0.090 90 0.3 28-Jul-86 12 0 6099198.590 616211.713 ! 1723.510 ! 0.133 ! 0. 110 90 0.5 31-Jul-86 12 a 6099198.590 616211.714 ! 1723.470 : 0.133 ! 0.070 90 0.3 04-Aug-86 12 0 6099198.590 -616211.719 ! 1723.520 ! 0.132 : 0. 120 90 1.3 18-Hug-86 12 0 6099198.560 616211.718 ! 1723.520 : 0.142 : 0. 120 186 0.7 22-Rug-86 12 • 6099198.5B0 616211.715 ! 1723.520 : 0.142 : 0. 120 270 0.8 02-Sep-86 12 0 6099198.580 616211.702 ! 1723.520 : 0.145 : 0. 120 270 1.2 •8-Sep-86 12 0 6099198.580 616211.722 ! 1723.520 : 0.141 ! 0. 120 90 3.3 U-Dec-86 12 0 6099198.550 616211.687 ! 1723.500 : 0.178 : 0. 100 229 0.5 18-Dec-86 12 0 6099198.550 616211.691 ! 1723.500 : 0.177 : 0. 100 90 0.6 15-May-87 12 0 6099198.497 616211.664 ! 1723.476 : 0.236 : 0.076 207 0.4 26-May-B7 12 0 6099198.473 616211.641 ! 1723.508 ! 0.266 : 0.108 224 3.0 03-Jun-87 12 0 6099198.473 616211.647 ! 1723.483 : 0.264 : 0.083 90 0.8 •9-Jun-87 12 0 6099198.469 616211.653 ! 1723.498 i 0.266 ! 0.098 124 1.2 18-Jun-87 12 0 6099198.482 616211.634 ', 1723.491 : 0.261 ! 0.091 304 2.6 24-Jun-B7 12 0 6099198.457 616211.643 ! 1723.505 ! 0.281 : 0. 105 160 4.4 •2-Jul-87 12 0 6099198.480 616211.634 ! 1723.483 : 0.263 ! 0.083 339 3. 1 05-Jul-87 12 0 6099198.468 616211.615 '. 1723.501 i 0.282 : 0.101 238 7.5 23-Jul-87 12 • 6099198.467 616211.632 ! 1723.491 ! 0.275 ! 0.091 93 0.9 24-Jul-87 12 0 6099198.462 616211.624 ,' 1723.488 : 0.283 : 0.068 238 9.4 25-Jul-87 12 a 6099198.469 616211.607 ! 1723.486 : 0.285 : 0.066 292 18.4 27-Jul-87 12 • 6099198.468 616211.624 ! 1723.478 : 0.278 : 0.078 93 8.5 -CUMULATIVE-31-jui-e? *, 12 0 02-Rug-87 ! 12 0 OS-flug-87 ! 12 0 06-Rug-87 '. 12 0 •7-flug-87 ! 12 0 11-flug-B? ! 12 0 13-Rug-87 ! 12 0 19-Rug-87 ! 12 0 21-Rug-B? : 12 0 23-flug-87 ! 12 Q 26-flug-87 J 12 0 6099198.452 6099198.489 6099198.442 6099198.437 6099198.440 6099198.443 6099198.456 6099198.438 6099198.446 6099198.447 6099198.484 616211.611 ' 1723.502 0. 298 ! 0. 102 219 5. 2 616211.602 1723.493 0. 270 : 0.093 346 19. 0 616211.597 1723.498 • . 313 : 0.098 186 15. 8 616211.587 1723.494 0. 322 ! 0.094 243 11. 2 616211.588 1723.503 0. 319 : 0. 103 18 3. 2 616211.597 1723.489 0. 312 i 0.089 72 2. 4 616211.611 1723.482 0. 294 : 0.082 47 9. 6 616211.600 1723.490 0. 315 ! 0.090 211 3. 5 616211.597 1723.490 0. 310 : 0.090 339 4. 3 616211.594 1723.481 0. 310 : 0.081 288 1. 6 616211.616 1723.493 0. 267 : 0.093 31 14. 3 VERTICAL LIMB MONITORING DflTfl STATION 17500? DRTE TIME -ACTUAL SURVEY-NORTHING EASTING !ELEVATION CUMULATIVE metres HQRIZ I VERT AZIMUTH HORIZ mm/day 31 -Ju l -87 12 0 6099208.909 616354.424 ! 1763.058 0.000 ! 0.000 02-flug-87 12 0 6099208.890 616354.429 ! 1763.050 0.020 ! -0.008 165 9.8 05-Rug-87 12 0 6099208.888 616354.421 ! 1763.059 0.021 : 0.001 256 2.7 06-Hug-87 12 0 6099208.896 616354.417 ! 1763.040 o.ois : -0.018 333 8.9 07-flug-87 12 0 6099208.887 616354.417 ! 1763.060 0.023 : 0.002 180 9.0 l l - f l u g - 8 7 12 0 6099208.891 616354.425 ! 1763.065 0.018 : 0.007 63 2.2 13-Rug-87 12 0 6099208.888 616354.416 ! 1763.063 0.022 : 0.005 252 4 .7 15-flug-87 12 0 6099208.892 616354.414 ! 1763.043 0.020 : -0.015 333 2.2 l ? - H u g - 8 ? 12 0 6099208.879 .616354.428 ! 1763.064 0.030 : 0.006 133 9.6 18-flug-87 12 0 609920B.879 616354.416 ! 1763.043 0.031 : -0.015 270 12.0 19-flug-87 12 0 6099208.869 616354.418 ! 1763.051 0.040 ! -0.007 169 10.2 21-Hug-87 12 0 6099208.890 616354.411 ! 1763.056 0.023 : -0.002 342 11.1 23-flug-a? 12 0 6099208.903 616354.410 ! 1763.048 0.015 : -0.010 356 6.5 25-flug-B7 12 0 6099208.893 616354.414 ! 1763.049 o.oi9 : -0.009 158 5.4 26-Rug-87 12 0 6099208.917 616354.459 ! 1763.076 0.036 : 0.018 62 51.0 l l - S e p - 8 7 12 0 6099208.926 616354.473 ! 1763.073 0.052 : 0.015 57 1.0 13-Sep-87 12 0 6099208.919 616354.463 ! 1763.067 0.040 : 0.009 235 6. 1 15-Sep-87 12 0 6099208.916 616354.467 ! 1763.091 0.044 : 0.033 127 2.5 17-Sep-8? 12 0 6099208.922 616354.458 ! 1763.068 0.036 : 0.010 304 5.4 23-Sep-87 12 0 6099208.918 616354.460 ! 1763.076 0.037 : 0.018 153 0.7 24-Sep-87 12 0 6099208.928 616354.461 ! 1763.064 0.042 : 0.006 6 10.0 29-Sep-87 12 0 6099208.917 616354.459 ! 1763.086 0.036 ! 0.028 190 2.2 02-act-87 12 0 6099208.949 616354.430 ! 1763.076 0.040 : 0.018 318 14.4 05-0ct-87 12 0 6099208.920 616354.460 ! 1763.073 0.038 : 0.015 134 13.9 08-0ct-87 12 0 6099208.919 616354.461 ! 1763.070 0.038 : 0.012 135 0.5 13-0ct-87 12 0 6099208.907 616354.449 ! 1763.079 0.025 : 0.021 225 3.4 17-0ct-87 12 0 6099208.911 616354.457 ! 1763.120 0.033 : 0.062 63 2.2 19-0ct-87 12 0 6099208. 923 616354. 444 1763. 060 0. 024 0. 002 313 a.e 19-0ct-87 12 0 6099208. 917 616354. 451 1763. 079 0. 028 0. 021 131 ERR 23-0ct-87 12 0 6099208. 918 616354. 454 1763. 072 0. 031 0. 014 72 0.8 27-0ct-87 12 0 6099208. 916 616354. 452 1763. 075 0. 029 0. 017 225 0.7 02-Nov-87 12 0 6099208. 920 616354. 435 1763. 075 0. 016 0. 017 283 2.9 D6-Nov-87 12 0 6099208. 912 616354. 450 1763. 074 0. 026 0. 016 118 4.3 10-Nov-87 12 0 6099208. 915 616354. 444 1763. 075 0. 021 • . 017 297 1.7 17-Nov-87 12 0 6099208. 915 616354. 430 1763. 131 0. 008 0. 073 270 2.0 Ol-Dec-87 12 0 6099208. 909 616354. 436 1763. 084 0. 012 0. 026 135 0.6 •8-Dec-87 12 • 6099208. 882 616354. 439 1763. 088 0. 031 0. 030 174 3.9 22-Dec-87 12 0 6099208. 907 616354. 435 1763. 060 0. O i l 0. 002 351 1.8 08-Jan-88 12 0 6099208. 890 616354. 455 1763. 091 0. 036 0. 033 130 1.5 VERTICAL LIMB MONITORING OATA STATION 175006 -ACTUAL SURVEY-DATE TIME NORTHING ERSTING ELEVATION HORIZ VERT AZIMUTH mm/day 3 1 - J u l - 8 7 12 0 — _ — 6099179.180 616309.730 1755.530 0.000 0.000 02-flug-B7 12 0 6099179.137 616309.696 1755.507 0.055 -0.023 218 27.4 05 -Aug-87 12 0 6099179.101 616309.664 1755.514 0. 103 -0.016 222 16. 1 06 -Aug-87 12 0 6099179.112 616309.666 1755.499 0.093 -0.031 10 11.2 07 -Aug-87 12 0 6099179.103 616309.653 1755.518 0.109 -0.012 235 15.8 l l - A u g - 8 7 12 0 6099179.095 616309.655 1755.510 0. 113 -0.020 166 2.1 13 -Aug-87 12 0 6099179.107 616309.654 1755.518 0. 105 -0.012 355 6.0 15 -Aug-87 12 0 6099179.107 616309.651 1755.504 0. 108 -0.026 270 1.5 17 -Aug-87 12 0 6099179.079 616309.650 1755.513 0. 129 -0.017 182 14.0 18 -Rug-87 12 0 6099179.088 '616309.644 1755.516 0. 126 -0.014 326 10.8 19 -Aug-87 12 0 6099179.086 616309.654 1755.503 0. 121 -0.02? 101 10.2 21 -Aug-87 12 0 6099179.088 616309.633 1755.503 0. 134 -0.027 275 10.5 23 -Aug-87 12 0 6099179.101 616309.638 1755.500 0.121 -0.030 21 7.0 2 5 -Aug-8? 12 0 6099179.085 616309.633 1755.504 0. 136 -0.026 197 8.4 -CUMULATIVE--metres- HORI; -ACTUAL SURVEY-VERTICAL LIMB MONITORING DATA STATION 175005 -CUMULATIVE-metres HORIZ DATE TIME NORTHING EASTING ELEVATION HORIZ VERT AZIMUTH mm/daq 31-Jul -87 12 0 6099159.780 616293.346 1752.736 0.000 0.000 02-Aug-87 12 0 6099159.717 616293.287 1752.710 0.086 -0.026 223 43.2 05-Aug-87 12 0 6099159.684 616293.257 1752.710 0. 131 -0.026 222 14.9 06-Aug-87 12 0 6099159.683 616293.253 1752.704 0. 134 -0.032 256 4. 1 07-Aug-87 12 0 6099159.688 616293.255 1752.716 0.129 -0.020 22 5.4 l l -Aug-87 12 0 6099159.685 616293.252 1752.721 0. 134 -0.015 225 1.1 13-Aug-87 12 0 6099159.675 616293.240 1752.719 0.149 -0.017 230 7 . 8 17-Aug-87 12 0 6099159.664 616293.242 1752.719 0. 156 -0.017 170 2.8 18-Aug-87 12 0 6099159.660 , 616293.225 1752.717 0.170 -0.019 257 17.5 19-Aug-87 12 0 6099159.635 616293.215 1752.707 0.195 -0.029 202 26.9 21-Aug-87 12 0 6099159.667 616293.229 1752.707 0. 163 -0.029 24 17.5 23-Aug-87 12 0 6099159.664 616293.215 1752.703 0.175 -0.033 258 7.2 25-Aug-87 12 0 6099159.670 616293.231 1752.713 0.159 -0.023 69 8.5 VERTICAL LIMB MONITORING DATA STATION 175004 ACTUAL SURVEY ! ! CUMULATIVE ! ! ! ! I metres ! ! HORIZ DATE !TIME ! NORTHING ! EASTING !ELEVATION ! ! HORIZ 1 VERT ! AZIMUTH ! mm/day ! 1 B - J u n - B 7 ! 12 0 1 6099152 .111 ! 616292 .412 ! 1752.191 ! ! 0.000 ! 0.000 ! ! ! 2 4 - J u n - B 7 ! 12 0 ! 6099152 .085 ! 616292 .409 ! 1752.201 ! ! 0 . 0 2 6 ! 0 . 010 ! 18? ! 4 . 4 ! 0 2 - J u l - 8 ? ! 12 0 ! 6099152 .052 ! 616292 .355 i 1752 .178 i! 0 . 0 8 2 ! - 0 . 0 1 3 ! 239 ! 7.9 ! 0 5 - J u l - B ? ! 12 0 ! 6099152 .056 ! 6 1 6 2 9 2 . 3 2 3 ! 1752 .177 ! ! 0 . 1 0 5 ! - 0 . 0 1 4 ! 277 ! 1 0 . 7 : 2 2 - J u i - B 7 : 12 o : 6099151.928 : 616292.204 : 1752.145 : : 0.277 : -0.046 : 223 : 10.a ! 2 3 - J u l - 8 7 ! 12 0 ! 6099151 .911 ! 616292 .198 ! 1752 .157 ! ! 0 . 2 9 3 ! - 0 . 0 3 4 ! 199 ! 18 .0 : 2 4 - J u i - 8 7 : 12 o : 6099151.912 : 6I6292.179 : 1752.154 0.306 : -0.037 : 273 : 19.0 H : 2 5 - J u i - 8 7 ; 12 0 : 6099151.923 : 616292.155 : 1752.142 : : 0.318 : -0.049 : 295 : 26.4 vo ! 2 7 - J u l - 8 7 ! 12 0 ! 6099151 .898 ! 616292 .156 ! 1 7 5 2 . 1 3 5 ! ! 0.333 ! - 0 . 0 5 6 ! 178 ! 12.5 o\ 1 Destroyed on July 2 7 , 1987 VERTICAL LIMB MONITORING DATA STATION 172006 ACTUAL SURVEY ! ! — CUMULATIVE \ ! ! ! ! metres ! ! HORIZ DATE iTIME ! NORTHING ! EASTING !ELEVATION i i HORIZ i VERT ! AZIMUTH ! mm/day 05- Aug-87 ! 12 0 ! 6099101.328 ! 616296.772 i 1723.242 i i 0.000 ! 0.000 ! ! 06- Aug-87 ! 12 0 ! 6099101.331 ! 616296.759 ! 1723.239 i i 0.013 ! -0.003 ! 283 ! 13.3 07- Aug-87 i 12 0 ! 6099101.328 ! 616296.757 ! 1723.252 i! 0.015 ,' 0.010 i 214 i 3.6 l l -Aug-87 ! 12 0 ! 6099101.320 i 616296.749 i 1723.251 ! ! 0.024 ! 0.009 ! 225 ! 2.8 13-Aug-87 ! 12 0 ! 6099101.308 ! 616296.742 \ 1723.254 0.036 ! 0.012 210 i 6.9 17- Aug-87 ! 12 0 ! 6099101.292 ! 616296.726 ! 1723.248 ! ! 0.058 ! 0.006 \ 225 ! 5.7 18- Aug-87 ! 12 0 ! 6099101.301 ! 616296.730 ! 1723.247 ! ! 0.050 ! 0.005 ! 24 ! 9 . 8 VERTICAL LIMB MONITORING DATA STATION 172005 -ACTUAL SURVEY-DATE ! TIME NORTHING ! EASTING ELEVATION ! HORIZ VERT AZIMUTH I rnm/dc y 16-Jun-86 ! 12 0 6099118.020 ' 616283.736 1723.930 ! 0. 000 0. 000 27-Jun-86 ! 12 0 6099118.000 616283.707 1723.930 ! 0. 035 0. 000 235 . 3. 2 Oe-Jul-86 i 12 0 6099117.890 ! 616283.706 1724.060 ! 0. 133 0. 130 181 : 10. 0 10-Jul-86 : 12 0 6099117.890 616283.700 1724.060 ! 0. 135 0. 130 270 3. 0 21-Jul -86 : 12 0 6099117.890 616283.686 1724.070 ! 0. 139 0. 140 270 ' 1. 3 24-Jul -86 ! 12 0 6099117.880 616283.685 1724.040 ! 0. 149 0. 110 186 3. 3 28-Jul -86 : 12 0 6099117.880 616283.684 1724.060 ! 0. 149 0. 130 270 0. 3 31-Jul -86 ! 12 0 6099117.880 616283.681 1724.020 ! 0. 150 0. 090 270 1. 0 04-Aug-86 ; 12 0 6099117.880 616283.682 1724.050 ! 0. 150 0. 120 90 0. 3 18-Aug-86 : 12 0 6099117.880 '616283.683 1724.060 ! 0. 150 0. 130 90 0. 1 22-Aug-86 : 12 0 6099117.880 616283.680 1724.060 ! 0. 151 0. 130 270 0. 7 02-Sep-86 : 12 0 6099117.880 616283.677 1724.050 ! 0. 152 0. 120 270 0. 3 08-Sep-86 : 12 0 6099117.880 616283.681 1724.060 ! 0. 150 0. 130 90 0. 7 18-0ec-86 : 12 0 6099117.820 616283.609 1724.050 ! 0. 237 0. 120 230 0. 9 26-May-87 : 12 0 6099117.736 616283.494 1724.034 ! 0. 373 0. 104 234 0. 9 03-Jun-87 : 12 0 6099117.712 616283.466 1724.025 ! 0. 410 0. 095 229 4. 6 09-Jun-87 : 12 0 6099117.697 616283.459 1724.029 ! 0. 426 0. 099 205 2. 8 18-Jun-87 : 12 0 6099117.694 616283.433 1724.020 ! 0. 445 0. 090 263 2. 9 24-Jun-87 : 12 0 6099117.692 616283.445 1724.038 ! 0. 438 0. 108 99 2. 0 02-Jul -87 : 12 0 6099117.666 616283.404 1724.022 ! 0. 485 0. 092 238 6. 1 05-Jul -87 : 12 0 6099117.652 616283.363 1724.033 ! 0. 524 0. 103 251 14. 4 22-Jul -87 : 12 0 6099117.573 616283.296 1724.025 ! 0. 627 0. •95 220 6. 1 23-Jul -87 : 12 0 6099117.603 616283.325 1724.023 ! 0. 585 0. 093 44 41. 7 24-Jul -87 : 12 0 ! 6099117.619 616283.332 1724.019 ! 0. 569 0. 089 24 17. 5 25-Jul -87 : 12 0 ! 6099117.600 616283.292 1724.018 ! 0. 611 0. •88 245 44. 3 27-Jul -87 ! 12 0 ! 6099117.573 616283.280 1724.011 ! 0. 639 0. 081 204 14. 8 -CUMULATIVE--metres-Destroyed Ju ly 27, 1987. VERTICAL LIMB MONITORING DHTR STRTION 169005 -ACTUAL SURVEY-DATE TIME NORTHING EASTING !ELEVATION HORIZ VERT AZIMUTH mm/dan 05-Aug-87 12 0 6099081.781 616276.595 ! 1692.730 0.000 0.000 06-flug-87 12 0 6099081.788 616276.591 ! 1692.728 0.008 -0.002 330 8. 1 07-flug-87 12 0 6099081.785 616276.585 ! 1692.731 0.011 0.001 243 6.7 l l -Rug-87 12 0 6099081.783 616276.588 ! 1692.729 0.007 -0.001 124 0.9 13-Rug-87 12 0 6099081.775 616276.589 ! 1692.733 0.008 0.003 173 4.0 17-flug-87 12 0 6099081.769 616276.583 ! 1692.730 0.017 0.000 225 2. 1 19-flug-87 12 0 6099081.771 616276.586 ! 1692.730 0.013 0.000 56 1.8 21-flug-87 12 0 6099081.772 616276.587 ! 1692.733 0.012 0.003 45 0.7 23-Rug-87 12 0 6099081.762 , 616276.588 ! 1692.723 0.020 -0.007 174 5.0 25-flug-87 12 0 6099081.774 616276.583 ! 1692.732 0.014 0.002 337 6.5 -CUMULATIVE--metres-VERTICAL LIMB MONITORING DRTfl STRTIDN 166005 RCTURL SURVEY ! ! CUMULATIVE ! ! ! ! ! —metres ! ! HORIZ DATE !TIME ! NORTHING 1 EASTING !ELEVATION ! ! HORIZ ! VERT ! AZIMUTH ! mm/day 05- Aug-87 ! 12 0 ! 6099068.565 ! 616255.885 ! 1665.266 ! ! 0.000 ! 0.000 ! ! 06- Rug-87 ! 12 0 ! 6099068.565 ! 616255.884 ! 1665.267 ! ! 0.001 ! 0.001 ! 270 '. 1.0 0?-Aug-87 ! 12 0 ! 6099068.571 ! 616255.882 ! 1665.269 1! 0.007 ! 0.003 ! 342 ! 6.3 l l -Aug-87 ! 12 0 ! 6099068.565 ! 616255.880 ! 1665.272 ! ! 0.005 ! 0.006 ! 198 ! 1.6 13-Rug-87 \ 12 0 ! 6099068.560 ! 616255.892 '• 1665.269 1! 0.009 ', 0.003 ! 113 ! 6.5 15-Rug-87 ! 12 0 ! 6099068.536 ! 616255.888 ! 1665.264 ! ! 0.029 ! -0.002 ! 189 ! 12.2 17-Aug-87 ! 12 0 ! 6099068.560 ! 616255.883 ! 1665.269 ,'! 0.005 ! 0.003 ! 348 ', 12.3 VERTICAL LIMB MONITORING DATA STATION 164005 -ACTUAL SURVEY-DATE TIME NORTHING EA5TING ELEVATION HORIZ VERT AZIMUTH mm/day 05-Aug-87 12 0 6099067.657 616235.579 1641.859 0.000 0.000 06-Aug-87 12 0 6099067.651 616235.576 1641.864 0.007 0.005 207 6.7 07-flug-87 12 0 6099067.665 616235.584 1641.862 0.009 0.003 30 16.1 l l -Rug-87 12 0 6099067.652 616235.583 1641.868 0.006 0.009 184 3.3 13-flug-87 12 0 6099067.645 616235.583 1641.868 0.013 0.009 180 3.5 15-Aug-87 12 0 6099067.627 616235.598 1641.864 0.036 0.005 140 11.7 17-Aug-87 12 0 6099067.646 616235.573 1641.871 0.013 0.012 307 15.7 19-Aug-87 12 0 6099067.637 616235.583 1641.869 0.020 0.010 132 6.7 21-Aug-87 12 0 6099067.636 616235.592 1641.869 0.025 0.010 96 4.5 23-Aug-87 12 0 6099067.618 '616235.596 1641.862 0.043 0.003 167 9.2 25-Rug-87 12 0 6099067.677 616235.616 1641.846 0.042 -0.013 19 31. 1 -CUMULATIVE--metres-VERTICAL LIMB MONITORING DATA STATION 50401 -ACTUAL SURVEY- CUMULATIVE— l 1 l 1 metres HORIZ DATE !TIME ! NORTHING EASTING !ELEVATION l H0RI2 VERT AZIMUTH mm/day 16-Jun-86 ! 12 0 ! 6099243.370 616245. 155 ! 1774. 130 0.000 0. 000 27-Jun-86 ! 12 0 ! 6099243.310 616245. 172 ! 1774. 320 0.062 0. 190 164 5. / 08-Jul-86 : 12 0 •' 6099243.220 616245. 144 ! 1774. 440 0.150 0. 310 197 8. 6 10-Jul-86 : 12 0 ! 6099243.230 616245. 139 ! 1774. 430 0.141 0. 300 333 5. 6 21-Jul-86 : 12 0 ! 6099243.210 616245. 161 ! 1774. 440 0.160 0. 310 132 2. 7 28-Jul-86 : 12 0 ! 6099243.210 616245. 156 ! 1774. 430 0.160 0. 300 270 0. 7 31-Jul-86 : 12 0 ! 6099243.220 616245. 123 ! 1774. 410 0. 153 0. 280 287 11. 5 04-Aug-86 : 12 0 ! 6099243.220 616245. 130 '. 1774. 440 0.152 0. 310 90 1. 7 18-Aug-86 : 12 0 ! 6099243.210 616245. 139 ! 1774. 430 0. 161 0. 300 138 1. Q 22-Aug-86 : 12 0 ! 6099243.220 ' 616245. 134 ! 1774. 430 0.151 0. 300 333 2. 8 02-Sep-86 : 12 0 ', 6099243.220 616245. 127 '. 1774. 440 0.153 0. 310 270 0. 6 •8-Sep-86 : 12 0 ! 6099243.210 616245. 155 ! 1774. 440 0.160 0. 310 110 5. 0 ll-Dec-86 : 12 0 ! 6099243.240 616245. 117 ! 1774. 430 0.135 0. 300 308 0. 5 18-0ec-86 : 12 0 '. 6099243.230 616245. 118 ! 1774. 420 0.145 0. 290 174 1. 4 22-Apr-87 : 12 0 ! 6099243.158 616245. 090 ! 1774. 470 0.222 0. 340 201 0. 6 23-Apr-87 : 12 0 ! 6099243.154 616245. 095 ! 1774. 390 0.224 0. 260 129 6. 4 24-Apr-87 : 12 0 ! 6099243.156 616245. 093 ! 1774. 409 0.223 0. 279 315 2. 8 26-Apr-87 : 12 0 ! 6099243.162 616245. 092 ! 1774. 410 0.217 0. 280 351 3. 0 28-Apr-87 : 12 0 ! 6099243.155 616245. 079 ! 1774. 411 0.228 0. 281 242 7. 4 05-May-87 i 12 0 5 6099243.165 616245. 100 ! 1774. 414 0.212 0. 284 65 3. —» o 15-May-87 : 12 0 ! 6099243.167 616245. 101 ! 1774. 414 0.210 0. 284 27 0. 2 26-May-87 : 12 0 ! 6099243.161 616245. 092 ! 1774. 418 0.218 0. 288 236 1. G 03-Jun-87 : 12 0 ! 6099243.151 616245. 091 ! 1774. 396 0.228 0. 266 186 1. 3 09-Jun-87 : 12 0 ! 6099243.151 616245. 097 ! 1774. 405 0.227 0. 275 90 1. 0 18-Jun-87 : 12 0 ! 6099243.156 616245. 080 ! 1774. 402 0.227 0. 272 286 2. 0 24-Jun-87 : 12 0 ! 6099243.134 616245. 089 ! 1774. 427 0.245 0. 297 158 4. 0 02-Jul-87 i 12 0 1 6099243.144 616245. 084 ! 1774. 393 0.237 0. 263 333 1. 4 05-Jul-87 12 0 6099243. 147 616245.058 1774. 405 0. 243 0. 275 277 8. 7 24-Jul-8? 12 0 6099243. 159 616245.074 1774. 407 0. 226 0. 277 53 1. 1 27-Jul-87 12 0 6099243. 152 616245.081 1774. 401 0. 230 0. 271 135 3. 3 •2-Rug-8? 12 • 6099243. 134 616245.069 1774. 406 0. 251 0. 276 214 3. 6 05-flug-87 12 • 6099243. 121 616245.064 1774. 409 0. 265 0. 279 201 4. 6 ll-Rug-87 12 0 6099243. 133 616245.063 1774. 403 0. 254 0. 273 355 2. 0 13-Rug-87 12 0 6099243. 118 616245.055 1774. 405 0. 271 0. 275 208 8. 5 15-Rug-87 12 0 6099243. 119 616245.045 1774. 396 0. 274 0. 266 276 5. 0 l?-Rug-87 12 0 6099243. 115 616245.063 1774. 405 0. 271 0. 275 103 9. 2 19-Rug-87 12 0 6099243. 116 616245.054 1774. 407 0. 273 0. 277 276 4. 5 21-Rug-87 12 0 6099243. 128 616245.057 1774. 404 0. 261 0. 274 14 6. 2 23-flug-87 12 0 6099243. 148 616245.048 1774. 395 0. 246 0. 265 336 11. 0 25-Rug-87 12 0 6099243. 131 616245.065 1774. 404 0. 255 0. 274 135 12. 0 31-Rug-87 12 0 6099243. 170 616245.079 1774. 412 0. 214 0. 282 20 6. 9 Ol-Sep-87 12 Q 6099243. 173 616245.071 1774. 407 0. 214 0. 277 291 8. 5 10-Sep-87 12 0 6099243. 160 616245.085 1774. 409 0. 221 0. 279 133 2. 1 ll-Sep-87 12 0 6099243. 160 616245.089 1774. 407 0. 220 0. 277 90 4. 0 13-Sep-87 12 0 6099243. 166 ,616245.087 1774. 416 0. 215 0. 286 342 3. 2 15-Sep-87 12 0 6099243. 165 616245.082 1774. 435 0. 218 0. 305 259 2. 5 l?-Sep-87 12 • 6099243. 163 616245.079 1774. 424 0. 221 0. 294 236 1. 8 23-Sep-87 12 0 6099243. 163 616245.089 1774. 416 0. 21? 0. 286 90 1. 7 24-Sep-87 12 0 6099243. 161 616245.083 1774. 408 0. 221 0. 278 252 6. 3 25-Sep-87 12 • 6099243. 161 616245.075 1774. 413 0. 224 0. 283 . 270 8. 0 29-Sep-87 12 0 6099243. 163 616245.075 1774. 427 0. 222 0. 297 360 0. 5 08-0ct-87 12 • 6099243. 169 616245.078 1774. 413 0. 215 0. 283 27 0. 7 17-0ct-87 12 Q 6099243. 147 616245.075 1774. 470 0. 237 0. 340 188 2. 5 19-0ct-87 12 D 6099243. 158 616245.069 1774. 424 0. 229 0. 294 331 6. 3 23-0ct-87 12 • 6099243. 152 616245.068 1774. 411 0. 235 0. 281 189 1. 5 02-Nov-87 12 0 6099243. 159 616245.068 1774. 420 0. 228 0. 290 360 0. 7 06-Nov-B7 12 0 6099243. 154 616245.079 1774. 415 0. 229 0. 285 114 3. 0 VERTICAL LIMB MONITORING DATA STATION 175003B -ACTUAL SURVEY-DATE !TIME l NORTHING EASTING ELEVATION ! i HORIZ VERT AZIMUTH rnm/dc y 18-Jun-87 : 12 0 6099217.485 616231 .688 1752.667 ! 0.000 0.000 24-Jun-87 : 12 0 6099217.476 616231 .705 1752.689 ! 0.019 0.022 118 3. 2 02-Jul -87 : 12 0 6099217.481 616231 .689 1752.669 ! 0.004 0.002 287 2. 1 05-Jul -87 : 12 0 6099217.485 616231 .666 1752.675 ! 0.022 0.008 280 7. 8 22-Jul -87 : 12 0 6099217.478 616231 .679 1752.672 ! 0.011 0.005 118 0. 9 23-Jul -87 : 12 0 6099217.468 616231 .687 1752.679 ! 0.017 0.012 141 12. 8 24-Jul -87 : 12 0 6099217.494 616231 .686 1752.670 ! 0.009 0.003 358 26. 0 25-Jul -87 : 12 0 6099217.488 616231 .660 1752.673 ! 0.028 0.006 257 26. 7 27-Jul -87 : 12 0 6099217.471 616231 .685 1752.674 ! 0.014 0.007 124 15. 1 31-Jul -87 : 12 0 6099217.460 '616231 .653 1752.682 ! 0.043 0.015 251 8. 5 02-Aug-87 : 12 0 6099217.454 616231 .655 1752.666 ! 0.045 -0.001 162 3. 2 05-Aug-87 : 12 0 6099217.446 616231 .659 1752.673 ! 0.049 0.006 153 3. 0 06-Aug-87 : 12 0 6099217.458 616231 .663 1752.659 ! 0.037 -0.008 18 12. 6 07-Aug-87 : 12 0 6099217.448 616231 .652 1752.678 I 0.052 0.011 228 14. 9 l l -Aug-87 i 12 0 6099217.444 616231 .658 1752.681 ! 0.051 0.014 124 1. 8 13-Aug-87 : 12 0 6099217.446 616231 .658 1752.683 ! 0.049 0.016 360 1. 0 17-Aug-87 ! 12 0 6099217.445 616231 .665 1752.676 ! 0.046 0.009 98 1. 8 19-Aug-87 : 12 0 6099217.451 616231 .666 1752.672 ! 0.040 0.005 9 3. 0 21-Aug-87 : 12 0 6099217.454 616231 .655 1752.670 ! 0.045 0.003 285 5. 7 23-Aug-87 : 12 0 6099217.467 616231 .662 1752.640 ! 0.032 -0.027 26 7. 4 25-Aug-87 : 12 0 6099217.460 616231 .659 1752.680 ! 0.038 0.013 203 3. 8 26-Aug-87 : 12 0 6099217.448 616231 .653 1752.670 ! 0.051 0.003 207 13. 4 -CUMULflTIVE--metres-VERTICAL LIMB MONITORING DATA STATION 172004 -ACTUAL SURUEY- i l CUMULATIVE— t l i metres HORIZ DATE TIME ! NORTHING EASTING !ELEVATION 1 1 i HORIZ : VERT AZIMUTH mm/day 16-Jun-86 12 0 ! 6099198.720 616211 .741 ! 1723.400 : 0.000 : 0. 000 27-Jun-B6 12 0 ! 6099198.700 616211 .718 : 1723.410 : 0.030 ! 0. 010 229 2.8 08-Jul-86 12 0 ! 6099198.600 616211 .725 ! 1723.530 : 0.121 : 0. 130 176 9.1 10-Jul-86 12 0 ! 6099198.590 616211 .726 ! 1723.530 : 0.131 ! 0. 130 174 5.0 21-Jul-86 12 0 ! 6099198.590 616211 .710 ! 1723.500 : 0.134 : 0. 100 270 1.5 24-Jul-86 12 0 ! 6099198.590 616211 .711 ! 1723.490 : 0.133 ! 0. 090 90 0.3 28-Jul-86 12 0 ! 6099198.590 616211 .713 ! 1723.510 ,' 0.133 ; 0. 110 90 0.5 31-Jul-86 12 0 ', 6099198.590 616211 .714 ! 1723.470 : 0.133 : 0. 070 90 0.3 04-flug-86 12 0 ! 6099198.590 . 616211 .719 ! 1723.520 ! 0.132 : 0. 120 , 90 1.3 18-Aug-86 12 0 ! 6099198.580 616211 .718 ! 1723.520 : 0.142 : 0. 120 : 186 0.7 22-Aug-86 12 0 ! 6099198.580 616211 .715 ! 1723.520 : 0.142 : 0. 120 : 270 0.8 02-Sep-86 12 0 ! 6099198.580 616211 .702 ! 1723.520 : 0.145 ! 0. 120 : 270 1.2 08-Sep-86 12 0 ! 6099198.580 616211 .722 1723.520 : 0.141 : 0. 120 ' 90 3.3 ll-Dec-86 12 0 ! 6099198.550 616211 .687 ! 1723.500 : 0.178 : 0. 100 229 0.5 18-Dec-86 12 0 ! 6099198.550 616211 .691 ! 1723.500 ! 0.177 : 0. 100 , 90 0.6 15-May-87 12 0 ! 6099198.497 616211 .664 ! 1723.476 ! 0.236 : 0. 076 207 0.4 26-May-87 12 0 ! 6099198.473 616211 .641 ! 1723.508 ! 0.266 : 0. 108 224 3.0 03-Jun-87 12 0 ! 6099198.473 616211 .647 ! 1723.483 ! 0.264 : 0. 083 90 0.8 09-Jun-87 12 0 ! 6099198.469 616211 .653 ! 1723.498 : 0.266 : 0. 098 124 1.2 18-Jun-87 12 0 ! 6099198.482 616211 .634 ! 1723.491 : 0.261 : 0. 091 304 2.6 24-Jun-87 12 0 ! 6099198.45? 616211 .643 ! 1723.505 : 0.281 : 0. 105 160 4.4 02-Jul-87 12 0 ! 6099198.480 616211 .634 ! 1723.483 : 0.263 : 0. 083 . 339 3. 1 05-Jul-87 12 0 ! 6099198.468 616211 .615 : 1723.501 : 0.282 : 0. i o i : 238 7.5 23-Jul-B7 12 0 ! 6099198.467 616211 .632 ! 1723.491 ! 0.275 : 0. 091 93 0.9 24-Jul-87 12 0 ! 6099198.462 616211 .624 ,' 1723.488 : 0.283 ; 0. 088 : 238 9.4 25-Jul-87 12 0 '. 6099198.469 616211 .607 I 1723.486 : 0.285 : 0. 086 : 292 18.4 27-Jul-87 12 0 ! 6099198.468 616211 .624 ! 1723.478 ! 0.278 : 0. 078 : 93 8.5 31-Jul-87 12 0 6099198. 452 616211 .611 02-nug-87 12 0 6099198. 489 616211 .602 05-flug-87 12 0 6099198. 442 616211 .597 06-nug-87 12 • 6099198. 437 616211 .587 07-Hug-87 12 0 6099198. 440 616211 .588 ll-flug-87 12 0 6099198. 443 616211 .597 13-Rug-87 12 0 6099198. 456 616211 .611 19-Rug-87 12 • 6099198. 438 616211 .600 21-Rug-87 12 0 6099198. 446 616211 .597 23-Rug-87 12 0 6099198. 447 616211 .594 26-fiug-87 12 0 6099198. 484 616211 .616 1723.502 0.298 0. 102 219 5.2 1723.493 0.270 0.093 346 19.0 1723.498 0.313 0.098 186 15.8 1723.494 0.322 0.094 243 11.2 1723.503 0.319 0. 103 18 3.2 1723.489 0.312 0.089 72 2.4 1723.482 0.294 0.082 47 9.6 1723.490 0.315 0.090 211 3.5 1723.490 0.310 0.090 339 4.3 1723.481 0.310 0.081 288 1.6 1723.493 0.267 0.093 31 14.3 APPENDIX H Monitoring data f o r the Sept 18, 1988 F a i l u r e . 207 VERTICAL LIMB MONITORING DflTR STATION 7903 A C T U A L SURVEY ! ! - — C U M U L A T I VEL ! ! i ! ! metres ! ! HORIZ D A T E ! T I M E ! NORTHING ! E A S T I N G ! E L E V A T I O N I! HORIZ ! V E R T ! AZ IMUTH ! mm/day 27-Aug-88 ! 12 0 ! 99011.204 ! 16342.813 ! 1692.471 ! ! 0.000 ! 0.000 ! ! 31-Aug-88 ! 12 0 ! 99011.197 ! 16342.798 ! 1692.488 ! ! 0.017 ! 0.017 ', 245 4.1 03-Sep-88 ! 12 0 ! 99011.196 ! 16342.797 ! 1692.492 \ \ 0.018 ! 0.021 ,' 225 ! 0.5 06-Sep-88 ! 12 0 ! 99011.193 ! 16342.791 ! 1692.484 ! ! 0.025 ! 0.013 ! 243 ! 2.2 09-Sep-88 ! 12 0 ! 99011.183 ! 16342.782 ! 1692.509 ',! 0.037 ', 0.038 222 ! 4.5 12-Sep-88 ! 12 0 ! 99011.182 ! 16342.782 ! 1692.496 ! ! 0.038 ! 0.025 ! 180 ! 0.3 15-Sep-88 i 12 0 ! 99011.178 ! 16342.775 ! 1692.497 ! ! 0.046 ! 0.026 ! 240 ! 2.7 17-Sep-88 ', 12 0 ! 99011.172 ', 16342.770 ! 1692.497 \ \ 0.054 ! 0.026 ! 220 ! 3.9 Destroyed on Sept 18, 1988 VERTICAL LIMB MONITORING DRTR STATION 7051 -ACTUAL SURVEY-DATE TIME NORTHING EASTING ELEVATION HORIZ VERT AZIMUTH mm/day 23-Jun-88 12 0 99050.618 16336.683 1714.653 0.000 0.000 30-Jun-88 12 0 99050.559 16336.605 1714.634 0.098 -0.019 233 14.0 16-Jul-88 12 0 99050.510 16336.556 1714.625 0. 167 -0.028 225 4.3 21-Ju1-88 12 0 99050.507 16336.549 1714.609 0. 174 -0.044 247 1.5 27-Jul-88 12 0 99050.493 16336.538 1714.621 • . 191 -0.032 218 3.0 03-Aug-88 12 0 99050.488 16336.520 1714.590 0.208 -0.063 254 2.7 10-Aug-88 12 0 99050.472 16336.506 1714.607 0.229 -0.046 221 3.0 17-Aug-88 12 0 99050.465 16336.484 1714.600 0.251 -0.053 252 3.3 24-Aug-88 12 0 99050.432 16336.443 1714.598 0.304 -0.055 231 7.5 27-Aug-88 12 0 99050.417 16336.430 1714.597 0.323 -0.056 221 6.6 31-Aug-88 12 • 99050.395 16336.400 1714.583 0.360 -0.070 234 9.3 03-Sep-88 12 0 99050.382 16336.387 1714.579 0.379 -0.074 225 6. 1 06-Sep-88 12 0 99050.367 16336.367 1714.567 0.404 -0.086 233 8.3 09-Sep-88 12 0 99050.343 16336.339 1714.595 0.440 -0.058 229 12.3 12-Sep-88 12 0 99050.327 16336.315 1714.571 0.469 -0.082 236 9.6 15-Sep-88 12 0 99050.296 16336.278 1714.561 0.517 -0.092 230 16.1 17-Sep-88 12 0 99050.246 16336.214 1714.555 0.599 -0.098 232 40.6 -CUMULATIVE--metres-Destroyed on Sept 18, 1988 VERTICAL LIMB MONITORING DATA STATION 7905 -ACTUAL SURVEY-DATE TIME NORTHING EASTING ELEVATION HORIZ VERT AZIMUTH mm/dag 29-May-8B 12 0 99126.481 16248.179 1692.071 0.000 0.000 13-Jun-88 12 0 99126.475 16248.169 1692.081 0.012 0.010 239 0.8 17-Jun-88 12 0 99126.474 16248.170 1692.075 0.011 0.004 135 0.4 23-Jun-88 12 0 99126.472 16248.164 1692.070 0.017 -0.001 252 1.1 30-Jun-88 12 0 99126.454 16248.130 1692.077 0.056 0.006 242 5.5 16-Jul-88 12 0 99126.451 16248.145 1692.079 0.045 0.008 101 1.0 21-Jul -88 12 0 99126.456 16248.148 1692.063 0.040 -0.008 31 1.2 27-Jul -88 12 0 99126.448 16248.140 1692.080 0.051 0.009 225 1.9 03-Aug-88 12 0 99126.453 . 16248.134 1692.046 0.053 -0.025 310 1.1 10-Aug-88 12 • 99126.449 16248.138 1692.074 0.052 0.003 135 0.8 17-Aug-88 12 0 99126.452 16248.135 1692.071 0.053 0.000 315 0.6 24-Aug-88 12 0 99126.447 16248.126 1692.071 0.063 0.000 241 1.5 31-Aug-88 12 0 99126.442 16248.126 1692.073 0.066 0.002 180 0.7 06-Sep-88 12 0 99126.447 16248.130 1692.068 0.060 -0.003 39 1. 1 12-Sep-88 12 0 99126.441 16248.125 1692.066 0.067 -0.005 220 1.3 18-Sep-88 12 0 99126.437 16248.122 1692.075 0.072 0.004 217 0.8 22-Sep-88 12 0 99126.430 16248.121 1692.081 0.077 0.010 188 1.8 25-Sep-88 12 • 99126.431 16248.122 1692.074 0.076 0.003 45 0.5 -CUMULATIVE--metres-VERTICAL LIMB MONITORING DATA STATION 7601 -ACTUAL SURVEY-DATE TIME NORTHING EASTING ELEVATION HORIZ VERT AZIMUTH mm/day 16-May-88 12 0 99047.267 16287.290 1667.678 0.000 0.000 24-May-88 12 0 99047.265 16287.292 1667.292 0.003 -0.386 135 0.4 29-May-88 12 0 99047.264 16287.292 1667.679 0.004 0.001 180 0.2 13-Jun-B8 12 0 99047.259 16287.280 1667.686 0.013 0.008 247 0.9 1?-Jun-B8 12 0 99047.258 16287.283 1667.679 0.011 0.001 108 0.8 27-Jul -88 12 0 99047.216 16287.280 1667.673 0.052 -0.005 184 1.1 03-Aug-88 12 0 99047.219 16287.272 1667.649 0.051 -0.029 291 1.2 10-Aug-88 12 0 99047.215 16287.273 1667.665 0.055 -0.013 166 0.6 17-Aug-88 12 0 99047.216 . 16287.266 1667.667 0.056 -0.011 278 1.0 24-Aug-88 12 0 99047.210 16287.258 1667.663 0.065 -0.015 233 1.4 31-Aug-88 12 0 99047.203 16287.254 1667.666 0.073 -0.012 210 1.2 06-Sep-B8 12 0 99047.205 16287.253 1667.653 0.072 -0.025 333 0.4 12-Sep-88 12 0 99047.198 16287.248 1667.663 0.081 -0.015 216 1.4 -CUMULATIVE--metres-Oestroyed on Sept 18, 1988 VERTICAL LIMB MONITORING DATA STRTION 175006 -ACTUAL SURVEY- CUMULATIVE m e t r e s HORIZ DATE TIME NORTHING EASTING ELEVATION HORIZ VERT AZIMUTH mm/day O B - D e c - 8 7 12 0 9 9 1 6 7 . 0 9 0 16306 .420 1750 .793 0 . 0 0 0 0 . 0 0 0 2 2 - D e c - 8 7 12 0 99167 .094 16306.431 1750 .746 0 . 0 1 2 - 0 . 0 4 7 70 0 . 8 2 2 - F e b - 8 8 12 0 9 9 1 6 7 . 0 8 5 16306 .432 1750 .784 0 . 0 1 3 - 0 . 0 0 9 174 0 . 1 2 9 - F e b - 8 8 12 0 9 9 1 6 7 . 0 8 8 16306.431 1750 .799 0 . 0 1 1 0 . 0 0 6 342 0 . 5 0 9 - M a r - 8 8 12 0 9 9 1 6 7 . 0 9 8 16306 .425 1750 .804 0 . 0 0 9 0 .011 329 1.3 1 5 - M a r - 8 8 12 0 99167 .078 16306 .433 1750 .792 0 . 0 1 8 - 0 . 0 0 1 158 3 . 6 2 8 - M a r - 8 8 12 0 99167 .091 16306 .416 1750 .795 0 . 0 0 4 0 . 0 0 2 307 1.6 0 5 - A p r - 8 8 12 0 9 9 1 6 7 . 0 8 8 16306 .415 1750 .796 0 . 0 0 5 0 . 0 0 3 198 0 . 4 2 6 - A p r - 8 8 12 0 9 9 1 6 7 . 0 7 7 16306.411 1750 .797 0 . 0 1 6 0 . 0 0 4 200 0 . 6 16 -May -88 12 0 99167 .074 16306 .405 1750 .797 0 . 0 2 2 0 . 0 0 4 243 0 . 3 2 4 - M a y - 8 8 12 0 9 9 1 6 7 . 0 6 9 16306 .405 1750.811 0 . 0 2 6 0 . 0 1 8 180 0 . 6 2 9 - M a y - 8 8 12 0 9 9 1 6 7 . 0 7 0 16306 .405 1750 .809 0 . 0 2 5 0 . 0 1 6 360 0 . 2 1 3 - J u n - 8 8 12 0 9 9 1 6 7 . 0 6 3 16306 .397 1750 .800 0 . 0 3 5 0 . 0 0 7 229 0 . 7 1 7 - J u n - 8 B 12 0 99167 .060 16306 .394 1750 .807 0 . 0 4 0 0 . 0 1 4 225 1.1 2 4 - J u n - 8 8 12 0 99167 .057 16306 .386 1750 .805 0 . 0 4 7 0 . 0 1 2 249 1.2 1 6 - J u l - 8 8 12 0 99166 .996 16306 .319 1750 .790 0 . 1 3 8 - 0 . 0 0 3 228 4 . 1 2 1 - J u l - 8 8 12 0 99166 .991 16306 .313 1750 .792 0 . 146 - 0 . 0 0 1 230 1.6 2 7 - J u l - 8 8 12 0 99166 .994 16306 .322 1750 .790 0 . 137 - 0 . 0 0 3 72 1.6 0 3 - R u g - 8 8 12 0 99166 .994 16306 .316 1750 .775 0 . 1 4 2 - 0 . 0 1 8 270 0 . 9 1 0 - A u g - 8 8 12 0 99166 .992 16306 .313 1750 .786 0 . 145 - 0 . 0 0 7 236 0 . 5 1 7 - A u g - 8 8 12 0 99166 .991 16306 .310 1750 .764 0 . 148 - 0 . 0 2 9 252 0 . 5 2 4 - A u g - 8 8 12 0 99166 .980 16306 .296 1750 .779 0 . 166 - 0 . 0 1 4 232 2 . 5 2 7 - A u g - 8 8 12 0 99166 .974 16306 .292 1750 .775 0 . 173 - 0 . 0 1 8 214 2 . 4 3 1 - A u g - 8 8 12 0 99166 .965 16306 .282 1750 .778 0 . 186 - 0 . 0 1 5 228 3 . 4 0 3 - S e p - 8 8 12 0 99166 .965 16306 .277 1750.761 0 . 190 - 0 . 0 3 2 270 1.7 0 6 - S e p - 8 8 12 0 99166 .955 16306 .266 1750 .775 0 . 2 0 5 - 0 . 0 1 8 228 5 . 0 0 9 - S e p - 8 8 12 0 99166 .957 16306 .266 1750 .774 0 . 2 0 3 - 0 . 0 1 9 360 0 . 7 12-Sep-ee 15-sep-ee l?-Sep-88 18- Sep-8B 19- Sep-88 22-Sep-8B 25-Sep-88 12 o : 99166. 12 o : 99166. 12 o : 99166. 12 o : 99166. 12 o : 99166. 12 0 : 99166. 12 o : 99166. 950 i 16306.263 948 ! 16306.257 944 ! 16306.250 927 ! 16306.232 919 ! 16306.229 915 ! 16306.227 913 ! 16306.223 1750.775 0.210 : -0.018 203 2.5 1750.775 0.216 ! -0.018 252 2. 1 1750.777 0.224 ! -0.016 240 4.0 1750.766 0.249 ! -0.027 227 24.8 1750.771 0.256 : -0.022 201 8.5 1750.767 0.261 : -0.026 207 1.5 1750.772 0.265 : -0.021 243 1.5 VERTICAL LIMB MONITORING DATA STATION 172501 -ACTUAL SURVEY- I l CUMULATIVE ! i i 1 l i t l metres ! HORIZ DATE :TIME • NORTHING EASTING ELEVATION ! _ • HORIZ ! VERT : 1 AZIMUTH mm/day 24-Jun-Oa • : 12 0 99113.707 16306.167 1731.568 ! 0.000 ! 1 o.ooo : 16-Jul-88 : 12 0 99113.591 16306.038 1731.478 ! 0.173 : -0.090 ! 228 7.9 21-Ju1-88 : 12 0 99113.580 16306.027 1731.470 ! 0.189 : -0.098 : 225 3. 1 27-Jul-88 : 12 0 99113.578 16306.029 1731.478 ! 0.189 : -0.090 : 135 0.5 03-Aug-B8 : 12 0 99113.571 16306.017 1731.456 ! 0.202 ! -0.H2 : 240 2.0 10-Aug-88 : 12 0 99113.563 16306.005 1731.458 ! 0.217 ! - • . n o : 236 2. 1 17-Aug-B8 : 12 0 99113.553 16305.992 1731.429 ! 0.233 : -0.139 : 232 2.3 24-Aug-88 : 12 0 99113.519 16305.953 1731.420 ! 0.285 : -0.148 ! 229 7.4 27-Aug-88 : 12 0 99113.503 16305.940 1731.412 ! 0.305 : -0.156 : 219 6.9 31-Aug-88 : 12 0 99113.483 16305.912 1731.393 ! 0.339 : -0.175 : 234 8.6 03-Sep-88 : 12 0 99113.468 16305.898 1731.377 ! 0.360 : -•.191 : 223 6.6 06-Sep-88 : 12 0 99113.453 16305.875 1731.375 ! 0.387 : -0.193 : 237 9.2 D9-Sep-88 : 12 0 99113.441 16305.859 1731.360 ! 0.407 : -0.208 : 233 6.7 12-Sep-88 i 12 0 99113.418 16305.838 1731.345 ! 0.438 : -0.223 : 222 10.4 15-Sep-88 : 12 0 99113.390 16305.800 1731.324 ! 0.485 : -0.244 : 234 15.7 17-Sep-88 : 12 0 99113.343 16305.747 1731.291 ! 0.556 : -0.277 : 228 35.4 Destroyed on Sept 19, 1988 VERTICAL LIMB MONITORING DATA STATION 7901 ! DATE ! TI ME i i —.' NORTHING ! — _ — — I EASTING !ELEVATION ! I 1 HORIZ VERT AZIMUTH mm/day ! 16-May-8B : 12 o : 99087.022 ! 16288.429 ! 1695.038 i 0.000 0.000 ! 24-May-88 : 12 0 i 99087.019 ! 16288.433 ! 1695.046 : 0.005 0.008 127 0.6 ! 29-May-88 : 12 o : 99087.01? ! 16288.428 ! 1695.039 : 0.005 0.001 248 1.1 ! 13-Jun-B8 : 12 o : 99087.003 ! 16288.408 i 1695.046 ! 0.028 0.008 235 1.6 ! 17-Jun-88 ; 12 0 i 99087.001 ! 16288.414 ! 1695.039 : 0.026 0.001 108 1.6 ! 23-Jun-88 : 12 o : 99086.995 ! 16288.402 ! 1695.039 ! 0.038 0.001 , 243 2.2 ! 30-Jun-88 ; 12 o : 99086.956 ! 16288.354 ! 1695.027 ! 0.100 -0.011 ' 231 8.8 ! 16-Jul-B8 ! 12 o : 99086.933 ! 16288.337 : 1695.01? : 0.128 -0.021 . 216 1.8 to 21-Jul-88 : 12 o : 99086.933 ! 16288.334 ! 1695.000 ! 0.130 -0.038 : 270 0.6 V 27-Jul-88 : 12 o : 99086.923 ! 16288.326 : 1695.021 : 0. 143 -0.017 ! 219 2. 1 i 03-Aug-B8 : 12 0 ; 99086.923 i 16288.315 ! 1694.984 ! 0.151 -0.054 : 270 1.6 ! 10-Rug-88 : 12 0 i 99086.914 ! 16288.312 ! 1695.012 : 0. 159 -0.026 : 198 1.4 ! 17-Aug-88 ; 12 o : 99086.911 ! 16288.299 ! 1695.006 : 0. 171 -0.032 : 257 1.9 ! 24-Aug-88 : 12 o : 99086.895 ! 16288.279 : 1695.001 : 0.197 -0.037 i 231 3.7 ! 27-Aug-88 : 12 o : 99086.886 ! 16288.273 ! 1695.004 ! 0.207 -0.034 : 214 3.6 ! 31-Aug-88 i 12 o : 99086.875 ! 16288.261 ! 1694.989 : 0.223 -0.049 : 227 4. 1 ! 03-Sep-88 : 12 o : 99086.872 ! 16288.257 ! 1694.988 : 0.228 -0.050 : 233 1.7 ! 06-Sep-88 i 12 o : 99086.865 ! 16288.249 ! 1694.983 : 0.239 -0.055 : 229 3.5 ! 09-Sep-88 : 12 o : 99086.851 ! 16288.232 ! 1694.996 : 0.261 -0.042 : 231 7.3 ! 12-Sep-88 : 12 o : 99086.844 ! 16288.226 ! 1694.987 : 0.270 -0.051 : 221 3. 1 ! 15-Sep-88 : 12 o : 99086.832 ! 16288.210 ! 1694.980 : 0.290 -0.058 : 233 6.7 ! 17-Sep-88 : 12 o : 99086.811 ! 16288.184 ! 1694.969 : 0.323 -0.069 ! 231 16.7 -CUMULATIVE--metres-Destroyed on Sept 18, 1988 VERTICAL LIMB MONITORING DATA STATION 7602 -ACTUAL SURVEY-DATE .'TIME NORTHING EASTING !ELEVATION -CUMULATIVE-metres HORIZ ! VERT AZIMUTH 16- May-88 24-May-88 29- May-88 13-Jun-88 17- Jun-88 23- Jun-88 30- Jun-88 16- Jul-88 21-Jul-88 27-Jul-88 03-Hug-88 10-Aug-88 17- Aug-88 24- Aug-88 31- Aug-88 06-Sep-B8 12-Sep-88 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 99006.543 99006.540 99006.538 99006.533 99006.533 99006.530 99006.505 99006.499 99006.503 99006.495 99006.498 99006.492 99006.493 99006.489 99006.482 99006.484 99006.477 16317.693 16317.695 16317.693 16317.686 16317.690 16317.678 16317.649 16317.648 16317.649 16317.645 16317.638 16317.637 16317.629 16317.624 16317.618 16317.619 16317.613 1666.550 1666.560 1666.560 1666.564 1666.558 1666.563 1666.549 1666.557 1666.529 1666.554 1666.523 1666.546 1666.546 1666.547 1666.546 1666.540 1666.543 0. 0. 0. 0.000 0.004 .005 ,012 .010 0.020 0.058 0.063 0.059 0.068 0.071 0.076 0.081 0.088 0.097 0.095 0.104 0.000 0.010 0.010 0.014 0.008 0.013 -0.001 0.007 -0.021 0.004 -0.027 -0.004 -0.004 -0.003 -0.004 -0.010 -0.007 146 225 234 90 256 229 189 14 207 293 189 277 231 221 27 221 Destroyed on Sept 18, 1988 VERTICAL LIMB MONITORING DATA STATION 7603 -ACTUAL SURVEY-DATE !TIME 1 1 1 NORTHING ! 1 EASTING !ELEVATION ! HORIZ : VERT AZIMUTH ! mm/day 16-May-88 ! 12 o : 98974.584 ! 16342.614 ! 1665.577 : 1 o.ooo : 0.000 1 1 1 24-May-88 ! 12 o : 98974.580 ! 16342.618 ! 1665.589 : 0.006 : 0.012 135 : 0.7 29-May-88 : 12 • : 98974.578 ! 16342.615 ! 1665.587 : o.oo6 : 0.010 236 : 0.7 13-Jun-88 ! 12 o : 98974.575 ! 16342.609 ! 1665.590 : o.oio : 0.013 243 : 0.4 17-Jun-88 : 12 o : 98974.575 .' 16342.612 ! 1665.585 ! o.oo9 : 0.008 90 : 0.7 23-Jun-88 ; 12 0 i 98974.572 ! 16342.605 ! 1665.590 ! o.oi5 : 0.013 247 : 1.3 30-Jun-88 : 12 o : 98974.552 ! 16342.581 ! 1665.584 : 0.046 : 0.007 . 230 : 4.5 16-Jul-88 : 12 o : 98974.550 ! 16342.581 i 1665.586 ! 0.047 : 0.009 180 : 0. 1 21-Jul-88 : 12 o : 98974.553 i 16342.587 ! 1665.570 : o.04i : -0.007 . 63 : 1.3 27-Jul-8B : 12 0 ; 98974.548 ! 16342.581 ! 1665.583 : 0.049 : o.oo6 : 230 : 1.3 03-Aug-88 ! 12 0 ! 98974.550 ! 16342.578 i 1665.560 i 0.050 : -0.017 304 : 0.5 10-Aug-88 : 12 o : 98974.543 ! 16342.570 ! 1665.578 : 0.060 : o.ooi : 229 : 1.5 17-Aug-88 : 12 o : 98974.544 ! 16342.565 ! 1665.574 ! 0.063 : -0.003 : 281 : 0.7 24-flug-88 : 12 o : 98974.541 ! 16342.563 ! 1665.579 : 0.067 : 0.002 : 214 ! 0.5 31-Rug-88 : 12 0 i 98974.535 ! 16342.560 ! 1665.579 : 0.073 : 0.002 : 207 : 1.0 06-Sep-88 i 12 o : 98974.538 i 16342.558 ! 1665.571 : 0.072 ! -0.006 : 326 : 0.6 12-Sep-88 i 12 o : 98974.533 ! 16342.556 ! 1665.580 : 0.077 : 0.003 ' 202 : 0.9 -CUMULATIVE-- m e t r e s - HORIZ Destroyed on Sept 18, 1988 VERTICAL LIMB MONITORING DATA STATION 175004 -ACTUAL SURVEY— —CUMULATIVE i l metres HORIZ DATE TIME ! NORTHING : EASTING [ELEVATION HORIZ VERT AZIMUTH mm/day 22-Feb-88 12 0 ! 99175.641 ! 16271.938 ! 1749.897 0.000 0.000 29-Feb-88 12 0 ! 99175.649 ! 16271.929 ! 1749.913 0.012 0.016 312 1.7 09-Mar-88 12 0 ! 99175.659 ! 16271.924 ! 1749.926 0.023 0.029 333 1.2 15-Mar-88 12 0 ! 99175.643 i 16271.933 ! 1749.894 0.005 -0.003 151 3.1 28-Mar-88 12 0 99175.654 i 16271.918 ! 1749.912 0.024 0.015 306 1.4 04-Apr-88 12 0 ! 99175.652 ,' 16271.916 ! 1749.910 0.025 0.013 225 0.4 26-Apr-88 12 0 ! 99175.643 ! 16271.916 ! 1749.916 0.022 0.019 180 0.4 16-May-88 12 • ! 99175.640 i 16271.906 ! 1749.918 0.032 0.021 253 0.5 24-May-8e 12 0 ! 99175.637 ! 16271.903 ! 1749.925 0.035 0.028 225 0.5 29-May-88 12 0 ! 99175.635 ! 16271.905 ! 1749.928 0.034 0.031 135 0.6 13-Jun-88 12 0 ! 99175.632 ! 16271.899 ! 1749.917 0.040 0.020 243 0.4 17-Jun-88 12 0 ! 99175.628 ! 16271.898 ! 1749.925 0.042 0.028 194 1.0 24-Jun-88 12 0 ! 99175.625 ! 16271.890 ! 1749.922 0.051 0.025 249 1.2 16-Jul-88 12 0 ! 99175.578 ! 16271.841 ! 1749.911 0.116 0.014 226 3.1 21-Jul-88 12 0 ! 99175.575 ! 16271.837 ! 1749.909 0. 121 0.012 233 1.0 27-Jul-88 12 0 ! 99175.578 ! 16271.846 ! 1749.912 0. 112 0.015 72 1.6 03-Aug-88 12 0 ! 99175.580 : 16271.843 ! 1749.895 0. 113 -0.002 304 0.5 10-Aug-88 12 0 ! 99175.579 ! 16271.842 ! 1749.911 0. 114 0.014 225 0.2 17-Aug-88 12 0 ! 99175.578 ! 16271.842 ! 1749.888 0. 115 -0.009 180 0. 1 24-Aug-8B 12 0 ! 99175.571 : 16271.829 ! 1749.904 0.130 0.007 242 2. 1 31-Aug-88 12 0 ! 99175.561 : 16271.821 ', 1749.901 0.142 0.004 219 1.8 06-Sep-88 12 0 ! 99175.557 ! 16271.815 ! 1749.909 0. 149 0.012 236 1.2 12-Sep-88 12 0 ! 99175.551 ! 16271.809 ! 1749.905 0. 157 0.008 225 1.4 18-Sep-88 12 0 ! 99175.538 ! 16271.793 ! 1749.901 0. 178 0.004 231 3.4 19-Sep-88 12 0 ! 99175.534 ! 16271.793 ! 1749.899 0. 180 0.002 180 4.0 22-Sep-88 12 0 ! 99175.529 ! 16271.789 ! 1749.900 0. 186 0.003 219 2.1 25-Sep-88 12 0 ! 99175.528 ! 16271.790 ! 1749.899 0. 186 0.002 135 0.5 VERT1CRL LIMB MONITORING DflTR STATION 7604 -ACTUAL SURVEY-DATE TIME NORTHING EASTING '.ELEVATION ) HORIZ VERT AZIMUTH mm/day 27-Jul-B8 12 0 99132.576 16222.883 l ! 1668.211 0.000 0.000 03-Rug-88 12 0 99132.580 16222.881 ! 1668.280 0.004 0.069 333 0.6 10-Aug-88 12 0 99132.57? 16222.882 ! 1668.305 0.001 0.094 162 0.5 17-Aug-88 12 0 99132.580 16222.878 ! 1668.307 0.006 0.096 307 0.7 24-Rug-88 12 0 99132.576 16222.873 '. 1668.307 0.010 0.096 231 0.9 31-Rug-88 12 0 99132.573 16222.874 ! 1668.302 0.009 0.091 162 0.5 06-Sep-88 12 0 99132.579 16222.876 ! 1668.296 0.008 0.085 18 1.1 12-Sep-88 12 0 99132.573 16222.874 '. 1668.308 0.009 0.097 198 ' 1.1 18-Sep-88 12 0 99132.574 16222.875 ! 1668.314 0.008 0. 103 45 0.2 22-Sep-88 12 0 99132.568 16222.876 ! 1668.304 0.011 0.093 171 . 1.5 25-Sep-88 12 0 99132.569 ' 16222.877 '. 1668.309 0.009 0.098 45 ' 0.5 -CUMULRTIVE--metres- HORI; VERTICAL LIMB MONITORING DATA STATION 7401 DATE ITIME i i — —. ' NORTHING i EASTING !ELEVATION 1 HORIZ : 1 VERT AZIMUTH mm/day 30-Jun-88 : 12 o : 98997.557 ! 16298.399 ! 1643.839 1 o.ooo : 0.000 16-Jul-88 : 12 0 i 98997.553 ! 16298.406 ! 1643.843 0.008 ! 0.004 120 0.5 21-Jul -BB : 12 o ; 98997.558 i 16298.411 ! 1643.827 0.012 : -0.012 45 1.4 27-Jul-88 : 12 o : 98997.551 ! 16298.405 ! 1643.844 o.ooe : 0.005 221 1.5 03-Aug-88 ; 12 o : 98997.555 ! 16298.398 ,' 1643.819 0.002 : -0.020 300 1.2 10-Aug-88 : 12 o : 98997.551 ! 16298.397 ! 1643.837 0.006 : -0.002 194 0.6 17-Aug-88 : 12 o : 98997.552 ! 16298.390 ! 1643.838 o.oio : -0.001 278 1.0 24-Aug-88 : 12 o ; 98997.549 ! 16298.388 ! 1643.844 0.014 : 0.005 214 0.5 31-Aug-88 : 12 o : 98997.543 ! 16298.388 ! 1643.841 o.oiB : 0.002 180 0.9 06-Sep-88 : 12 o : 98997.547 ! 16298.389 ! 1643.831 o.oi4 : -0.008 14 0.7 12-Sep-88 : 12 0 ; 98997.542 ! 16298.386 ! 1643.845 0.020 ! 0.006 211 1.0 -CUMULATIVE--metres-D e s t r o y e d on Sept 18, 1988 VERTICAL LIMB MONITORING DATR STATION 7402 -ACTUAL SURVEY-DATE TIME NORTHING EASTING !ELEVATION HORIZ VERT AZIMUTH mm/day 30-Jun-B8 12 0 98922.361 16359.688 1644.578 0.000 0.000 16-Jul-8B 12 0 98922.360 16359.695 ! 1644.581 0.007 0.003 98 0.4 21-Jul-88 12 0 98922.364 16359.698 ', 1644.563 0.010 -0.015 37 1.0 27-Jul-88 12 0 98922.359 16359.693 ! 1644.582 0.005 0.004 225 1.2 03-Aug-88 12 0 98922.361 16359.689 ! 1644.556 0.001 -0.022 297 0.6 10-Rug-88 12 0 98922.351 16359.676 ! 1644.575 0.016 -0.003 232 2.3 17-Aug-88 12 0 98922.351 16359.669 ! 1644.572 0.021 -0.006 270 1.0 24-Aug-88 12 0 98922.346 16359.670 ! 1644.576 0.023 -0.002 169 0.7 31-Aug-8e 12 0 98922.343 16359.666 ! 1644.578 0.028 0.000 233 0.7 06-5ep-88 12 0 98922.346 16359.662 ! 1644.568 0.030 -0.010 307 0.8 12-Sep-88 12 0 98922.341 ' 16359.663 ! 1644.584 0.032 0.006 169 0.8 18-Sep-88 12 0 98922.340 16359.662 ! 1644.577 0.033 -0.001 225 0.2 22-Sep-88 12 0 98922.336 16359.664 ! 1644.577 0.035 -0.001 153 1.1 25-Sep-88 12 0 98922.336 16359.664 ! 1644.580 0.035 0.002 0 0.0 -CUMULATIVE--met res - HORIZ VERTICAL LIMB MONITORING DflTH STRTION 7404 ACTUAL SURVEY ! ! CUMULflT IVE ! : : :: metres : : HORIZ DATE . T I M E ! NORTHING ! EASTING iELEVATION !! HORIZ ! VERT ! AZIMUTH i mm/day I I I ~" — , — — — , , | —————— t ~ . , — — — — — — — 27-Jul-88 ! 12 0 ! 99033.012 ! 16269.980 ! 1642.927 !! 0.000 ! 0.000 ! ! 03-Aug-88 ! 12 0 ! 99033.015 ! 16269.973 ! 1642.905 !! 0.008 \ -0.022 ! 293 ! 1.1 10-Rug-88 ! 12 0 ! 99033.012 I 16269.975 .' 1642.929 !! 0.005 i 0.002 ! 146 ! 0.5 17-flug-88 '. 12 0 ', 99033.013 '. 16269.970 '. 1642.929 !! 0.010 ! 0.002 ! 281 ! 0.7 24-Rug-B8 ! 12 0 ! 99033.008 ! 16269.964 ! 1642.924 !! 0.016 ! -0.003 ! 230 ! 1.1 31-Hug-88 ! 12 0 ! 99033.004 ! 16269.965 ! 1642.926 !! 0.017 ! -0.001 ! 166 ! 0.6 06-Sep-88 ! 12 0 ! 99033.008 ! 16269.965 1 1642.920 !! 0.016 ! -0.007 ! 360 ! 0.7 12-Sep-88 ! 12 0 ! 99033.003 ! 16269.963 ! 1642.933 i ! 0.019 ! 0.006 ! 202 ! 0.9 Destroyed on Sept 18, 1988 VERTICAL LIMB MONITORING DRTR STATION 7902 -ACTUAL SURVEY-- CUMULATIVE 1 1 metres HORIZ DATE [TIME NORTHING ! _____ 1 _ EASTING !ELEVATION HORIZ VERT AZIMUTH mm/day 16-May-88 ! 12 0 99041.417 ! 16320.183 ! 1693.548 0.000 0.000 24-May-88 ! 12 0 99041.412 ! 16320.186 ! 1693.562 0.006 0.014 149 0.7 29-May-88 : 12 0 99041.410 ! 16320.182 ! 1693.556 0.007 0.008 243 0.9 13-Jun-88 : 12 0 99041.398 ! 16320.164 ! 1693.559 0.027 0.011 236 1.4 17-Jun-88 ! 12 0 99041.396 ! 16320.163 ! 1693.553 0.029 0.005 207 0.6 23-Jun-88 ! 12 0 99041.389 ! 16320.154 ! 1693.557 0.040 0.009 232 1.9 30-Jun-88 : 12 0 99041.350 ! 16320.097 ! 1693.545 0.109 -0.003 236 9.9 XKXKXDESTROYEDXXKXK APPENDIX I UDEC plot s for the 2 x 6 m case with no step. Plots included: Cross-section of wall showing structure. X v e l o c i t y vs machine time at the 172 0 m bench crest a f t e r 13000 cycles. Y v e l o c i t y vs machine time at the 172 0 m bench crest a f t e r 13 000 cycles. X displacement Vs machine time at the 1720 m bench crest a f t e r 13 000 cycles. X v e l o c i t y vs machine time at the 1720 m bench cr e s t a f t e r 66000 cycles. Y v e l o c i t y vs machine time at the 1720 m bench crest a f t e r 66000 cycles. Cross-section of wall showing structure and v e l o c i t y p r o f i l e at 66000 cycles. 224 Job tltl» : MARMOT VERTICAL LIMB: XVEL V I MACHINE TIME AT THE 1720 • BENCH CREST. UDEC (Version 1.50) legend 9/0B/1BBB Oft SB cycle 19000 -3.91E-02 <hi«t l> 2.16E-0B Univ. of British Columbia Dept. of Baologlcal sclanca (NiONK-e) -1.0 5 -l.B hi H X -2.B -3.0 -3.8 MACHINE TIME (sec) ( N 1 0 M M - 1 ) r o r o job t l t l a : MARMOT VERTICAL LIMB: YVEL va MACHINE TIME AT THE 1720 • BENCH CREST. UDEC (Version 1.50) legend 9/08/1989 09:41 eye la 13000 -8.33E-03 <hlat 2> B.09E-03 Univ. of British Coluabla Dapt. of Geological Bclonca (M10NM-3) 4 .0 2.0 n a X -4.0 -6.0 -8.0 4 . 0 MACHINE TIME (sec) (MlOMM-l) to to CO job t i t l e : MARMOT VERTICAL LIMB: X DISPLACEMENT va MACHINE TIME FOR BENCH CREST AT 1720 • . UDEC (Version 1.50) legend 9/05/1989 09:47 cycle 13000 -4.88E-03 <hlet 3>-6.28E-07 Univ. of BriMah Columbia Dept. of Geological Science (M10NN-3) -.8 -1.0 • -1.8 « -2.0 I .„ -2.8 2 -3.0 H h 2 Hi X I ~ 3 B -4.0 5 -4.8 ~l 1 1 1 1 1 1 1.0 1.8 2.0 2.8 3.0 3.8 4.0 MACHINE TIME (sec) ( N 1 0 M M - 1 ) lob t l t l * : MARMOT VERTICAL LIMB: YVEL va MACHINE TIME AT THE 1720a BENCH FACE. ro o UDEC (Version 1.50) legend 12/09/19BB 11: 48 eyela 06000 -8.8BE-03 <hlat 2> 3.37E-03 Univ. of British Coluaola dept. of Geological Be lance (M10*M-S) .0 -1.0 -2.0 -3.0 S -4.0 H S -8.0 a -6.0 -7.0 -8.0 -i 1 1 1 1 — — i 1 1 1 r 1.0 1.2 1.4 1.6 l .B 2.0 2.2 2.4 2.6 MACHINE TIME (sec) (M10MM 0) to u> APPENDIX J UDEC plot s for the 2 x 6 m case with a i m step. Plots included: Cross-section of wall showing structure before excavation. Cross-section of wall showing structure. X v e l o c i t y vs machine time at the 1660 m bench cr e s t a f t e r 13500 cycl e s . Y v e l o c i t y vs machine time at the 1660 m bench crest a f t e r 13500 cycl e s . X v e l o c i t y vs machine time at the 1720 m bench crest a f t e r 26000 cycl e s . Y v e l o c i t y vs machine time at the 1720 m bench cr e s t a f t e r 2 6000 cycles. Cross-section of wall showing structure and v e l o c i t y p r o f i l e at 26000 cycles. 232 r o u i Job t i t l e : MARMOT VERTICAL LIMB: XVEL va MACHINE TIME AT THE 1660a BENCH CREST. UDEC (Version 1.50) legend 13/08/1989 09: 88 cycle 13300 -3.40E-02 <nlat B> 2.B0E-03 Univ. of Brltlah Columbia Dept. of Geological Science (M10MM-2) -.5 at " 1 0 H H -1.5 3 -2.0 -2.8 -3.0 3.0 4.0 MACHINE TIME (sec) s.o (ttlOMM-1) to CTl lob t i t l e : MARMOT VERTICAL LIMB: YVEL va MACHINE TIME AT THE 1660a BENCH CREST. UDEC (Version 1.S0J legend 12/05/1989 10:03 eye la 13300 -B.90E-03 <hlat 6> 2.36E-02 Univ. of British Coluabla Dept. of eeologlcal Science (N10MN-2) 2.0 1.5 n 1.0 X n H U a •• .0 -.a L7— • - -- — 1.0 2.0 3.0 4.0 MACHINE TIME (sec) 5.0 (M10MM-1) to -4 job t i t l e : MARMOT VERTICAL LIMB: XVEL ve MACHINE TIME AT THE 1720a BENCH CREST. UDEC (Version i.50j legend 12/0B/1SB9 10: 09 eyela 26000 -1.09E-02 <hlat 1>-4.70E-0B Univ. of Brltlah Coluabla Dapt. of Geological Science (M10Nt t -2 ) -.2 -.4 -.8 -1.0 ~I 1 1 1 1 1 1 1.0 1.0 1.1 1.1 1.1 1.1 1.1 MACHINE TIME (sec) (N10«» 0) Job t i t l e : MARMOT VERTICAL LIMB: YVEL V S MACHINE TIME AT THE 1720a BENCH CREST. UDEC (Version i.SOJ legend 12/0S/19B9 10: 12 eyela 26000 -9.46E-04 <hlat 2> 2.BBE-04 Univ. of British Coluabla Dapt. of Beologlcel Science (W10HM-4) 2.0 (0 -4.0 -6.0 -a.o ~l 1 1 1 1 1 1 1.0 1.0 1.1 1.1 1.1 1.1 1.1 MACHINE TIME (sec) (MIOttM 0) J 239 APPENDIX K UDEC p l o t s f o r the 2 x 6 m case with a 2 m step. P l o t s included: Cross-section of wall showing structure. X v e l o c i t y vs machine time at the 1720 m bench cr e s t a f t e r 14500 cycles. Y v e l o c i t y vs machine time at the 1720 m bench c r e s t a f t e r 14500 cycles. X displacement Vs machine time at the 1720 m bench c r e s t a f t e r 14500 cycles. 240 to *k to Job t i t l e : MARMOT VERTICAL LIMB: XVEL va MACHINE TIME AT THE 1720B BENCH CREST. UDEC (Version 1.50) legend g/os/isaa oa 29 cycle 14900 -2.32E-02 <hlat 1> 1.19E-03 Univ. of Brltleh Coluasla •apt. of Geological Science (M10MM-2) ! -fn O -1-2 3 X -1.6 -2.0 1.0 2.0 3.0 4.0 S.O MACHINE TIME (sec) (MlOMtt-l) to lob t i t l e : MARMOT VERTICAL LIMB: YVEL ve MACHINE TIME AT THE 1720* BENCH CREST. UDEC (Version 1.50) legend 9/09/1988 09:30 cycle 14500 -B.48E-03 <hlst 2> 1.78E-02 Univ. of British Coluable Dept. of Beologlcal Science (MlONM-2) 1.6 1.2 to X H H U 3 X -.4 1.0 2.0 3.0 4.0 5.0 MACHINE TIME (sec) (ttlOttM-l) to ]0b t i t l e : MARMOT VERTICAL LIMB: BEDDING JOINTS SPACING 2a. JOINTS SPACIN6 6n. 2a STEP. UOEC (Version 1.50) legend 7/0B/1SB9 23:38 cycle 13500 -4.43E-03 <hlet 3>-8.77E-08 Univ. of British Columbia Dept. of BeolOBicel Science (N10NN-3) - .6 -1.0 * -1.5 -2.0 at a i * -2.5 * S -3.0 t-2 -3.5 i i IS a -4.0 ~i 1 1 1 1 1 1 1 1 r 1.0 1.5 2.0 2.5 3.0 3.6 4.0 4.5 5.0 MACHINE TIME (sec) (N10MN-1) APPENDIX L UDEC pl o t s f o r the 2 x 6 m case with a 3 m step. Plots included: Cross-section of wall showing structure. X v e l o c i t y vs machine time at the 1720 m bench cr e s t a f t e r 15900 cycles. Y v e l o c i t y vs machine time at the 1720 m bench cr e s t a f t e r 15900 cycles. 245 to 10b tit10 : MARMOT VERTICAL LIMB: XVEL va MACHINE TIME AT THE 1720 • BENCH CREST. UDEC (Version 1.50) legend 9/09/1988 11: 17 eye la 19900 -2.6BE-02 <hlat 1> 1.44E-04 Univ. of Brltlah Coluabla Oapt. of Saologleal Selanca (MlONtt-2) - .9 ^ -1.0 to S -1.8 H U a -2.0 X -2.8 MACHINE TIME (sec) ( N 1 0 M M - 1 ) 00 Job t i t l e : MARMOT VERTICAL LIMB: YVEL ve MACHINE TIME AT THE 1720 a BENCH CREST. UDEC (Version 1.50J legend 9/08/1989 11:21 eye la 18900 -3.B7E-03 <nlet 2> 1.37E-02 Univ. of Brltlah Coluabla Dapt. of Geological Science (N10NN-2) 1.2 1.0 a > X H O 3 1.0 2.0 3.0 4.0 5.0 MACHINE TIME (sec) (M10MM-1) APPENDIX M UDEC p l o t s for the 2 x 10 m case with no step. Plots included: Cross-section of wall showing structure. X v e l o c i t y vs machine time at the 1720 m bench cr e s t a f t e r 14500 cycles. Y v e l o c i t y vs machine time at the 1720 m bench cr e s t a f t e r 14500 cycles. X v e l o c i t y vs machine time at the 1720 m bench cr e s t a f t e r 26000 cycles. Y v e l o c i t y vs machine time at the 1720 m bench c r e s t a f t e r 26000 cycles. Cross-section of wall showing structure and v e l o c i t y p r o f i l e a f t e r 26000 cycles. 249 to 01 H Job t l t l a : MARMOT VERTICAL LIMB: XVEL vs MACHINE TIME AT THE 1720 • BENCH CREST. UDEC (Version 1.50) legend 9/08/1989 10:37 eyela 14800 -2.95E-02 <hlat 1> 9.46E-08 Univ. of British Columbia Dapt. of ecological 8clanca (MlOMt-2) -.8 5 -l.o » n H CJ 3 -1.8 -2.0 -2.8 MACHINE TIME (sec) ( M 1 0 M M - 1 ) lob t l t l a : MARMOT VERTICAL LIMB: YVEL va MACHINE TIME AT THE 1780 • BENCH CREST. UDEC {Version 1.50) legend 9/0B/19B8 10:41 eye I t 14B00 -6.42E-03 Ollet 2> 4.9BE-03 Univ. of Brltlah Coluabla Dapt. of Oeologlcal sclanca (Niowi-a) 4.0 — 2.0 X H tt .0 a X -2 .0 -4.0 ~i 1 1 1 1 1 1 r 1.0 l .S 2.0 2.5 3.0 3.5 4.0 MACHINE TIME (sec) ( M 1 0 M M - 1 ) job t l t l a : MARMOT VERTICAL LIMK YVEL va MACHINE TIME AT THE 1720a BENCH CREST. UDEC (Version l.SOJ legend 12/osyisaa 10:23 eyela 260O0 -1.60E-02 <hlst 2> 4.13E-03 Univ. of British Coluabla Dept. of Geological Science (MlONM-2) . 4 to H CJ 3 B -1.2 - l .B MACHINE TIME (sec) (M10MM-1) to Ul UI APPENDIX N UDEC plot s f o r the 2 x 10 m case with 2.5m step. Plots included: Cross-section of wall showing structure. X v e l o c i t y vs machine time at the 172 0 m bench crest a f t e r 14500 cycles. Y v e l o c i t y vs machine time at the 1720 m bench crest a f t e r 14500 cycles. 256 lob t l t l a : MARMOT VERTICAL LIMB: XVEL va MACHINE TIME AT THE 1720 • BENCH CREST. UDEC (Version 1.50) legend 9/03/1988 09: BB cycla 14900 -1.21E-02 Ollat 1> 4.92E-04 Univ. of Brltlah Coluaola Oopt. of Geological Science (ttlOttft-2) H H U 8 a *, - .8-1.0 -1.2 4.0 S.O MACHINE TIME ( s e c ) ( M 1 0 M N - 1 ) r o u i job t l t l a : MARMOT VERTICAL LIMB: YVEL va MACHINE TIME AT THE 1720 • BENCH CRE8T UDEC (Version 1.50J legend 9/0S/1989 09:09 cycla 14500 -3.04E-03 <hiet e> 6.14E-03 Univ. of Brltlah Coluabla Oapt. of Baologlcal Bclanca (aioim-a) 6.0 5.0 4.0 3.0 a £ . 2.0 H 1.0 -1.0 -2.0 -3.0 MACHINE TIME (sec) APPENDIX 0 UDEC plots for the 2 x 10 m case a with 5 m step. Plots included: Cross-section of wall showing structure. X v e l o c i t y vs machine time at the 172 0 m bench crest a f t e r 15000 cycles. Y v e l o c i t y vs machine time at the 172 0 m bench crest a f t e r 15000 cycles. 260 cn Job t i t l e : MARMOT VERTICAL LIMB: XVEL va MACHINE TIME AT THE 1720 m BENCH CREST. UDEC (Version 1.50) legend 9/03/1 BBS 10: B6 eyela 15000 -1.32E-02 <hlat 1> 3.9BE-04 Univ. of Brltlah Coluabla Dept. of Beologlcal Science (N10MM-2) x H U a -1.0 -1.2 MACHINE TIME (sec) ( M 1 0 N N - 1 ) 

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