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UBC Theses and Dissertations

Evaluation of the Tri Star vibrocompaction probe Brown, David F. 1989

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EVALUATION OF THE TRI STAR VIBROCOMPACTION PROBE By DAVID F . BROWN BSc , The U n i v e r s i t y o f S t r a t h c l y d e , 1985 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF C I V I L ENGINEERING We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA August 1989 ® D a v i d F . Brown, 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 The University of British Columbia Vancouver, Canada DE-6 (2/88) i ABSTRACT The F r a n k i T r i S t a r method f o r deep compact ion o f s a t u r a t e d sands has been used on a p r o j e c t on A n n a c i s I s l a n d , V a n c o u v e r , B . C . , Canada. The o b j e c t i v e o f s o i l compact ion was t o s t a b i l i z e a deep s a t u r a t e d sand d e p o s i t , w h i c h was s u s c e p t i b l e t o l i q u e f a c t i o n d u r i n g s t r o n g e a r t h quakes . The p r o j e c t i n v o l v e d t h e compact ion o f a 750 f e e t l o n g by 15 f e e t wide s t r i p o f sand d e p o s i t s down t o 10m d e p t h . The sand was o v e r l a i n by a f i l l and a c l a y e y s i l t l a y e r o f 2 t o 5m t h i c k n e s s . Because o f t h e s i l t l a y e r and the p r e s e n c e o f t h i n s i l t and c l a y seams i n t h e s a n d , t h e s o i l was judged m a r g i n a l f o r v i b r o c o m p a c t i o n . T h e r e f o r e , e x t e n s i v e t e s t s were per formed on s i t e t o d e v e l o p the o p t i m a l compact ion p r o c e d u r e ( v i b r a t i o n t i m e , f r e q u e n c y o f compact ion and g r i d s p a c i n g ) . The compact ion p r o c e s s was m o n i t o r e d by v i b r a t i o n measurements on t h e ground s u r f a c e . In t h i s way, i t was p o s s i b l e t o d e t e r m i n e t h e t ime r e q u i r e d f o r d e n s i f i c a t i o n and t o e s t a b l i s h t h e o p t i m a l v i b r a t i o n f r e q u e n c y . In o r d e r t o m o n i t o r the T r i S t a r probe t h e c o n t r a c t o r c a r r i e d out t e s t i n g w i t h the h e l p o f t h e s i t e i n v e s t i g a t i o n f i r m , ConeTec , and i n c o l l a b o r a t i o n w i t h t h e U n i v e r s i t y o f B r i t i s h Co lumbia ( U . B . C . ) . U . B . C . m o n i t o r e d t h e l o n g term e f f e c t s , p r i m a r i l y w i t h t h e P i e z o m e t e r Cone T e s t (CPTU) and i n v e s t i g a t e d the use o f the F l a t P l a t e D i l a t o m e t e r (DMT) and S e i s m i c P i ezometer Cone T e s t (SCPTU). I n a d d i t i o n , t h e L a t e r a l S t r e s s P i ezometer Cone T e s t (LSCPTU) was u s e d . A l l t e s t i n g y i e l d e d b e f o r e and a f t e r t r e a t m e n t r e s u l t s , w i t h t h e CPTU g i v i n g p r o g r e s s i v e t i m e and d i s t a n c e e f f e c t s . The c o n t r a c t o r and c o n s u l t a n t a l s o c a r r i e d out S t a n d a r d P e n e t r a t i o n T e s t s ( S P T ) , CPTU t e s t i n g and measured ground s e t t l e m e n t b e f o r e , d u r i n g and a f t e r t r e a t m e n t . The t e s t i n g has p r o v e n t h a t t h e T r i S t a r system i s an e f f i c i e n t method t o compact s o i l d e p o s i t s which are s u s c e p t i b l e t o l i q u e f a c t i o n . In p a r t i c u l a r an i n c r e a s e i n p e n e t r a t i o n r e s i s t a n c e o f between 200 and 400% was r e c o r d e d and t h e p r o b e ' s zone o f i n f l u e n c e was found t o be o f 2m r a d i u s . The DMT and CPTU p r o v i d e d s i m i l a r r e s u l t s and on compar i son t o the LSCPTU sugges ted t h a t i n c r e a s e s i n r e l a t i v e d e n s i t y and l a t e r a l s t r e s s c o n t r i b u t e d a p p r o x i m a t e l y e q u a l l y t o the s o i l improvement. The SCPTU p r o v i d e d r e l a t i v e l y i n c o n c l u s i v e r e s u l t s . A d v i s o r : D r . R i c h a r d G . Campanel la i i TABLE OF CONTENTS ABSTRACT i TABLE OF CONTENTS i i L I S T OF FIGURES 7 . . . v i L I S T OF TABLES X ACKNOWLEDGEMENTS x i 1.0 INTRODUCTION 1 2 .0 REVIEW: DEEP COMPACTION OF SAND USING VIBRATORY PROBES 4 2 .1 I n t r o d u c t i o n 4 2.2 D e n s i f i c a t i o n F a c t o r s 5 2 . 2 . 1 S o i l Type 5 2 . 2 . 2 Degree o f S a t u r a t i o n and Water T a b l e L o c a t i o n 5 2 . 2 . 3 I n i t i a l R e l a t i v e D e n s i t y 7 2 . 2 . 4 I n i t i a l I n - s i t u S t r e s s e s 7 2 . 2 . 5 I n i t i a l S o i l S t r u c t u r e 7 2 . 2 . 6 Machine C h a r a c t e r i s t i c s 8 2 .3 M o n i t o r i n g o f V i b r o c o m p a c t i o n 8 2 . 3 . 1 I n t r o d u c t i o n 8 2 . 3 . 2 Methods o f M o n i t o r i n g 9 2 . 3 . 2 . 1 S e t t l e m e n t 9 2 . 3 . 2 . 2 P e n e t r a t i o n T e s t s 9 2 . 3 . 2 . 3 S e i s m i c T e s t s 10 2 . 3 . 2 . 4 R e a l Time M o n i t o r i n g 11 2.4 H i s t o r y 12 2 .5 V i b r o c o m p a c t i o n Methods U s i n g T o p d r i v e V i b r a t o r s 12 2 . 5 . 1 I n t r o d u c t i o n 12 2 . 5 . 2 The F o s t e r Probe 13 2 . 5 . 3 . The V i b r o Wing Probe 13 2 . 5 . 4 The V i b r o Rod Probe 14 2 . 5 . 5 The M y t i l u s Probe 14 2 . 5 . 6 The T r i S t a r Probe 15 3 .0 PROJECT DESCRIPTION 18 4 .0 RESEARCH SITE 20 4 .1 I n t r o d u c t i o n 20 4.2 R e g i o n a l Geology 20 4.3 S i t e D e s c r i p t i o n 22 5.0 SOIL INVESTIGATIONS 27 5 .1 F r a n k i T e s t i n g 27 5.2 U . B . C . T e s t i n g 30 5 . 2 . 1 S o i l P r o f i l e 30 i i i 6 .0 DENSIFICATION REQUIREMENTS 34 7 .0 TRI STAR VIBROCOMPACTION EQUIPMENT AND METHOD . 35 8 .0 DENSIFICATION TRIALS 38 8 .1 Aim o f the D e n s i f i c a t i o n T r i a l s . . . . . . . 38 8.2 M e a s u r i n g Equipment 38 8.3 T r i a l S i t e s 40 8 . 3 . 1 V i b r a t i o n Time and Frequency 40 8 . 3 . 2 Pore Water P r e s s u r e 40 8 . 3 . 3 Ground S u r f a c e S e t t l e m e n t 41 8 . 3 . 4 CPTU R e s u l t s 41 8 . 3 . 5 SPT R e s u l t s 41 8.4 P r o d u c t i o n Phase 47 8 . 4 . 1 E x e c u t i o n Parameters 47 8 . 4 . 2 D e n s i f i c a t i o n R e s u l t s 47 8 . 4 . 2 . 1 S e t t l e m e n t Measurements 47 8 . 4 . 2 . 2 SPT and CPTU R e s u l t s 51 9 .0 U . B . C . TESTING PROGRAM 58 9 .1 I n t r o d u c t i o n 58 9.2 I n - S i t u T e s t s 58 9 . 2 . 1 T e s t i n g V e h i c l e 58 9 . 2 . 2 T e s t s Performed 59 9 . 2 . 2 . 1 P i e z o c o n e P e n e t r a t i o n T e s t (CPTU) . 60 9 . 2 . 2 . 2 F l a t D i l a t o m e t e r P e n e t r a t i o n T e s t (DMT) 61 9 . 2 . 2 . 3 S e i s m i c P i e z o c o n e P e n e t r a t i o n T e s t (SCPTU) 63 9 . 2 . 2 . 4 L a t e r a l S t r e s s P i e z o c o n e P e n e t r a t i o n T e s t (LSCPTU) 64 9 .3 F i e l d T e s t Programme 66 9 . 3 . 1 O b j e c t i v e 66 9 . 3 . 2 Scope o f Work 66 10 .0 TEST RESULTS 70 10 .1 I n t r o d u c t i o n 70 10.2 CPTU Parameters 70 1 0 . 2 . 1 Cone B e a r i n g 71 1 0 . 2 . 1 . 1 Time E f f e c t 71 1 0 . 2 . 1 . 2 D i s t a n c e E f f e c t 73 1 0 . 2 . 2 S l e e v e F r i c t i o n 75 1 0 . 2 . 2 . 1 Time E f f e c t 75 1 0 . 2 . 2 . 2 D i s t a n c e E f f e c t 75 1 0 . 2 . 3 Pore Water P r e s s u r e Measured By CPTU . 78 1 0 . 2 . 4 F r i c t i o n R a t i o 80 1 0 . 2 . 4 . 1 Time E f f e c t 80 1 0 . 2 . 4 . 2 D i s t a n c e E f f e c t 80 10.3 DMT Parameters 82 1 0 . 3 . 1 I n t r o d u c t i o n 82 1 0 . 3 . 2 Parameter R e s u l t s 82 10.4 SCPTU Parameters 89 1 0 . 4 . 1 I n t r o d u c t i o n 89 1 0 . 4 . 2 Shear Modulus 89 i v 10 .5 LSCPTU Parameters 91 1 0 . 5 . 1 I n t r o d u c t i o n 91 1 0 . 5 . 2 L a t e r a l S t r e s s 91 10.6 C o n c l u s i o n s 93 11 .0 INTERPRETATION OF THE RESULTS AND GEOTECHNICAL PARAMETERS 94 11 .1 I n t r o d u c t i o n 94 11.2 CPTU R e s u l t s 94 1 1 . 2 . 1 F i l t e r i n g 94 11 .2 .2 Time Dependent B e h a v i o u r 95 1 1 . 2 . 2 . 1 Sand F i l l L a y e r 95 1 1 . 2 . 2 . 2 S i l t L a y e r 98 1 1 . 2 . 2 . 3 Medium Dense Sand L a y e r 100 1 1 . 2 . 2 . 4 C o n c l u s i o n s 100 1 1 . 2 . 3 D i s t a n c e Dependent B e h a v i o u r 102 1 1 . 2 . 3 . 1 Sand F i l l L a y e r 102 1 1 . 2 . 3 . 2 S i l t L a y e r 104 1 1 . 2 . 3 . 3 Medium Dense Sand L a y e r 104 1 1 . 2 . 3 . 4 C o n c l u s i o n s 107 11.3 R e l a t i v e D e n s i t y 108 1 1 . 3 . 1 I n t r o d u c t i o n 108 11 .3 .2 Time E f f e c t . . . 110 1 1 . 3 . 3 D i s t a n c e E f f e c t 110 1 1 . 3 . 4 C o n c l u s i o n s 113 11.4 Shear R e s i s t a n c e 113 1 1 . 4 . 1 I n t r o d u c t i o n 113 11 .4 .2 Time E f f e c t 114 1 1 . 4 . 3 D i s t a n c e E f f e c t 117 11 .4 .4 C o n c l u s i o n s 117 11 .5 Comparison o f G e o t e c h n i c a l Parameters . . . 119 1 1 . 5 . 1 Comparison o f t h e F r i c t i o n A n g l e E v a l u a t e d from the DMT and CPTU 119 1 1 . 5 . 2 Comparison o f Young' s Modulus E s t i m a t e d From t h e DMT and CPTU 121 1 1 . 5 . 3 Comparison o f Shear Modulus E v a l u a t e d From t h e CPTU and SCPTU 124 1 1 . 5 . 4 Comparison o f L a t e r a l S t r e s s E v a l u a t e d From t h e DMT and LSCPTU 127 1 1 . 5 . 5 Comparison Between L a t e r a l S t r e s s and R e l a t i v e D e n s i t y 129 11.6 C o n c l u s i o n s 132 12.0 COMPARISON WITH OTHER VIBROCOMPACTION SYSTEMS 134 12 .1 I n t r o d u c t i o n 134 12.2 D e n s i f i c a t i o n Comparison 134 12.3 G r i d S p a c i n g / P r o b e Diameter Comparison . . 136 12.4 Summary 138 13.0 CONCLUSIONS 139 13 .1 I n t r o d u c t i o n 139 13.2 P o s t C o n s t r u c t i o n C o n c l u s i o n s 139 13.3 CPTU R e s u l t s 140 13.4 DMT R e s u l t s 140 V 13 .5 SCPTU R e s u l t s 141 13 .6 LSCPTU R e s u l t s 141 13.7 I n t e r p r e t a t i o n o f G e o t e c h n i c a l Parameters . 141 13.8 Comparison t o O t h e r Probes 142 13.9 Recommendations F o r F u t u r e R e s e a r c h 7 . . . 142 REFERENCES 144 APPENDIX - F i e l d T e s t Data 148 v i L I S T OF FIGURES F i g u r e 1 Range o f P a r t i c l e S i z e D i s t r i b u t i o n f o r S u i t a b l e D e n s i f i c a t i o n by V i b r o c o m p a c t i o n , M i t c h e l l and K a t t i (1981) 6 F i g u r e 2 F r a s e r R i v e r D e l t a G e o l o g y , B l u n d e n , (1973) 21 F i g u r e 3 G e n e r a l S i t e P l a n , Gray Beverage S i t e . . 23 F i g u r e 4 S i t e P l a n o f T e s t L o c a t i o n s i n U . B . C . T e s t i n g A r e a 24 F i g u r e 5 C o r r e s p o n d i n g CPTU and SPT r e s u l t s B e f o r e D e n s i f i c a t i o n , M a s s a r s c h and Vannes te (1988) 28 F i g u r e 6 I n f l u e n c e o f G r a i n S i z e on q c / N r a t i o , R o b e r t s o n and Campane l la (1983) 29 F i g u r e 7 S o i l B e h a v i o u r Type C l a s s i f i c a t i o n C h a r t , R o b e r t s o n e t a l (1986) 31 F i g u r e 8 CPTU P r o f i l e 104CPT3 Showing I n t e r p r e t e d S o i l P r o f i l e 32 F i g u r e 9 T r i S t a r Probe P r i n c i p a l , M a s s a r s c h and Vannes te (1988) 36 F i g u r e 10 Cone R e s i s t a n c e P r o f i l e s B e f o r e and A f t e r D e n s i f i c a t i o n : C P T U ' s 7 and 10; F r a n k i T r i a l A r e a I 43 F i g u r e 11 Cone R e s i s t a n c e P r o f i l e s B e f o r e and A f t e r D e n s i f i c a t i o n : C P T U ' s 8, 12, and 13; F r a n k i T r i a l A r e a I I 44 F i g u r e 12 Cone R e s i s t a n c e P r o f i l e s A f t e r D e n s i f i c a t i o n a t G r i d C e n t r e P o i n t (CPTU 18) and a t D e n s i f i c a t i o n P o i n t (CPTU 20) : F r a n k i T r i a l A r e a 45 F i g u r e 13 P a t t e r n o f D e n s i f i c a t i o n P o i n t s D u r i n g t h e P r o d u c t i o n S t a g e , G r i d S p a c i n g o f 6 f e e t : a) 15 f e e t Wide Zone b) 10 f e e t Wide Zone, M a s s a r s c h and Vannes te (1988) 48 F i g u r e 14 D e s i r e d Working Scheme D u r i n g t h e P r o d u c t i o n S tage : Probe Depth and V i b r a t o r Frequency as a F u n c t i o n o f T ime; a) West H a l f o f S t r i p A r e a b) E a s t H a l f o f S t r i p A r e a , M a s s a r s c h and Vannes te (1988) 49 v i i F i g u r e 15 Cone R e s i s t a n c e P r o f i l e s B e f o r e and A f t e r D e n s i f i c a t i o n : C P T ' s 3 and 24; P r o d u c t i o n S t a g e , M a s s a r s c h and Vannes te (1988) . . . 54 F i g u r e 16 C o r r e s p o n d i n g CPT and SPT R e s u l t s A f t e r D e n s i f i c a t i o n : P r o d u c t i o n S t a g e , M a s s a r s c h and Vannes te (1988) 55 F i g u r e 17 Cone R e s i s t a n c e P r o f i l e s 6 Days A f t e r D e n s i f i c a t i o n 0, 1, 2, and 3m From the D e n s i f i c a t i o n P o i n t : P r o d u c t i o n S t a g e , M a s s a r s c h and Vannes te (1988) 56 F i g u r e 18 D e t a i l e d P l a n o f T r i a l A r e a C L 500 + 0 0 . 67 F i g u r e 19 E f f e c t o f Cone B e a r i n g W i t h Time 67, 82 and 209 Days A f t e r 72 F i g u r e 20 E f f e c t o f Cone B e a r i n g W i t h D i s t a n c e a t 0. 1 .2.3m From The C e n t r e l i n e (82 days a f t e r ) 74 F i g u r e 21 E f f e c t o f S l e e v e F r i c t i o n W i t h Time 67, 82, and 209 Days A f t e r 76 F i g u r e 22 E f f e c t o f S l e e v e F r i c t i o n W i t h D i s t a n c e a t 0, 1, 2, and 3m From the C e n t r e l i n e (82 days A f t e r 77 F i g u r e 23 E f f e c t o f Beh ind T i p p . w . p . W i t h Time 209 Days A f t e r 79 F i g u r e 24 E f f e c t o f F r i c t i o n R a t i o W i t h Time 67, 82, and 209 Days A f t e r 81 Depth B e f o r e and A f t e r 83 Depth B e f o r e and A f t e r 84 Depth B e f o r e and A f t e r 85 Depth B e f o r e and A f t e r 86 Depth B e f o r e and A f t e r 87 Depth B e f o r e and A f t e r 90 F i g u r e 31 L a t e r a l S t r e s s V e r s e s Depth B e f o r e and A f t e r D e n s i f i c a t i o n . 92 F i g u r e 25 P Q V e r s u s D e n s i f i c a t i o n F i g u r e 26 P-j^  V e r s u s D e n s i f i c a t i o n F i g u r e 27 I D V e r s u s D e n s i f i c a t i o n F i g u r e 28 K D V e r s u s D e n s i f i c a t i o n F i g u r e 29 E D V e r s u s D e n s i f i c a t i o n F i g u r e 30 G M a x V e r s u s D e n s i f i c a t i o n V l l l F i g u r e 32 F i l t e r e d and U n f i l t e r e d Cone B e a r i n g V e r s u s Depth 96 F i g u r e 33 Time V e r s u s Cone B e a r i n g f o r Sand F i l l L a y e r 97 F i g u r e 34 Time V e r s u s Cone B e a r i n g f o r S i l t L a y e r . 99 F i g u r e 35 Time V e r s u s Cone B e a r i n g f o r Medium Dense Sand L a y e r 101 F i g u r e 3 6 D i s t a n c e V e r s u s Cone B e a r i n g f o r Sand F i l l L a y e r 103 F i g u r e 37 D i s t a n c e V e r s u s Cone B e a r i n g f o r S i l t L a y e r 105 F i g u r e 38 D i s t a n c e V e r s u s Cone B e a r i n g f o r Medium Dense Sand L a y e r 106 F i g u r e 39 R e l a t i v e D e n s i t y R e l a t i o n s h i p f o r Uncemented and Unaged Q u a r t z Sands (adapted from B a l d i e t a l . 1982) 109 F i g u r e 40 E f f e c t o f R e l a t i v e D e n s i t y W i t h Time 67, 82, and 209 Days A f t e r I l l F i g u r e 41 E f f e c t o f R e l a t i v e D e n s i t y W i t h D i s t a n c e a t 0, 1, 2, and 3m from C e n t r e l i n e (82 days a f t e r ) 112 F i g u r e 42 R e l a t i o n s h i p Between Cone B e a r i n g and F r i c t i o n A n g l e f o r Uncemented and Unaged Q u a r t z Sands A f t e r (Robertson and C a m p a n e l l a , 1983) . . 115 F i g u r e 43 E f f e c t o f F r i c t i o n A n g l e W i t h Time 67, 82, and 209 Days A f t e r 116 F i g u r e 44 E f f e c t o f F r i c t i o n A n g l e W i t h D i s t a n c e a t 0, 1 ,2 , and 3m From t h e C e n t r e l i n e (82 Days A f t e r ) 118 F i g u r e 45 B e f o r e and A f t e r P e r c e n t a g e D i f f e r e n c e Comparison o f F r i c t i o n A n g l e E v a l u a t e d from CPTU and DMT 120 F i g u r e 46 R e l a t i o n s h i p Between Cone B e a r i n g and D r a i n e d Young' s Modulus f o r N o r m a l l y C o n s o l i d a t e d , Uncemented Q u a r t z Sands ( A f t e r R o b e r t s o n and C a m p a n e l l a , 1983) 122 F i g u r e 47 B e f o r e and A f t e r P e r c e n t a g e D i f f e r e n c e Comparison o f Young's Modulus E v a l u a t e d from CPTU and DMT 123 i x F i g u r e 48 R e l a t i o n s h i p Between Cone B e a r i n g and Dynamic Shear Modulus f o r N o r m a l l y C o n s o l i d a t e d , Uncemented Q u a r t z Sands (Rober t son and C a m p a n e l l a , 1986) 125 F i g u r e 49 Comparison o f G M E v a l u a t e d from -CPTU and SCPTU 126 F i g u r e 50 Comparison o f L a t e r a l S t r e s s E v a l u a t e d From t h e DMT and LSCPTU 128 F i g u r e 51 Percentage D i f f e r e n c e Comparison o f L a t e r a l S t r e s s E v a l u a t e d From t h e DMT and LSCPTU . 130 F i g u r e 52 A b i l i t y o f t h e T r i S t a r Probe t o D e n s i f y S o i l Around a S i n g l e Compact ion Probe Compared t o O t h e r Probes ( A f t e r H i t c h m a n , 1989) . . . 135 X L I S T OF TABLES T a b l e 1 C h a r a c t e r i s t i c s o f the ICE 812 V i b r a t o r . . 37 T a b l e 2 C o n v e r s i o n From E n g i n e Speed t o V i b r a t o r F r e q u e n c y , V i b r a t o r Type ICE 812 37 T a b l e 3 T r i S t a r V a r i a b l e s F o r T r i a l A r e a I and I I . 40 T a b l e 4 Average Ground S u r f a c e S e t t l e m e n t s 42 T a b l e 5 S t a n d a r d P e n e t r a t i o n T r i a l R e s u l t s f o r T r i a l A r e a I I 46 T a b l e 6 Compact ion P r o c e d u r e D u r i n g t h e P r o d u c t i o n Phase 50 T a b l e 7 Average Ground S u r f a c e S e t t l e m e n t s f o r P r o d u c t i o n S t a g e I m m e d i a t e l y A f t e r D e n s i f i c a t i o n 52 T a b l e 8 S t a n d a r d P e n e t r a t i o n Blowcounts f o r P r o d u c t i o n Stage 6 Days A f t e r D e n s i f i c a t i o n 53 T a b l e 9 D e t a i l s o f P e n e t r a t i o n T e s t s 68 T a b l e 10 D e t a i l s o f V a r i o u s V i b r o c o m p a c t i o n Systems ( A f t e r Hi tchman, 1989) 137 x i ACKNOWLEDGEMENTS I would l i k e t o thank my s u p e r v i s o r , P r o f e s s o r R . G . Campane l la f o r the c o o r d i n a t i o n o f t h i s t o p i c as a r e s e a r c h p r o j e c t , and f o r h i s a d v i c e and encouragement t h r o u g h o u t t h e work. The a s s i s t a n c e o f my f e l l o w s t u d e n t s o f t h e I n - s i t u T e s t i n g Group d u r i n g f i e l d t e s t i n g i s g r a t e f u l l y a p p r e c i a t e d . S i m i l a r l y , t h e t e c h n i c a l s u p p o r t s t a f f o f t h e Department o f C i v i l E n g i n e e r i n g , f o r t h e p r e p a r a t i o n and maintenance o f the i n - s i t u equipment . I acknowledge and I am g r a t e f u l f o r t h e f i n a n c i a l s u p p o r t o f t h e N a t u r a l S c i e n c e s and E n g i n e e r i n g R e s e a r c h C o u n c i l , p a i d t h r o u g h t h e Department o f C i v i l E n g i n e e r i n g G r a d u a t e R e s e a r c h A s s i s t a n t s h i p . I would l i k e t o thank F r a n k i Canada L t d . f o r t h e o p p o r t u n i t y t o be i n v o l v e d i n t h e p r o j e c t and s p e c i a l t h a n k s go t o M r . D. L e r o y , Branch Manager and M r . J . T r i f i l e t t e , P r e s i d e n t . The c o o p e r a t i o n o f t h e c l i e n t , G e r r i t s C o n s t r u c t i o n L t d . i s g r a t e f u l l y acknowledged, as i s t h e s i t e owner Gray Beverage I n c . Acknowledged a r e t h e s t a f f o f ConeTec I n v e s t i g a t i o n s L t d , who ensured t h e p r o p e r e x e c u t i o n o f t h e i n i t i a l t e s t i n g and who gave v a l u a b l e s u p p o r t d u r i n g t h e i n t e r p r e t a t i o n o f t h e t e s t r e s u l t s . I would a l s o l i k e t o thank D r . D. Snead and M r . K . Ko o f Cook P i c k e r i n g and Doy le L t d . , g e o t e c h n i c a l c o n s u l t a n t s f o r t h e p r o j e c t , f o r t h e i r w i l l i n g n e s s t o i n v e s t i g a t e t h e use o f t h e T r i S t a r probe and t o s u b s e q u e n t l y approve i t s u s e . 1 1 . 0 INTRODUCTION The T r i S t a r compact ion method i s a f u r t h e r improvement o f t h e o r i g i n a l F r a n k i Y - p r o b e , which was d e v e l o p e d d u r i n g t h e mid s e v e n t i e s f o r s o i l d e n s i f i c a t i o n p r o j e c t s i n B e l g i u m (Holeyman, 1988) by S . A . F r a n k i N . V . o f B e l g i u m . A heavy v i b r a t o r i s mounted on t o p o f a p r o b e which i s v i b r a t e d i n t o t h e s o i l . The v i b r a t i o n s a r e i n t h e v e r t i c a l d i r e c t i o n i n c o n t r a s t t o t h e v i b r o f l o t ( S p a r k s , 1975) which v i b r a t e s h o r i z o n t a l l y . E x t e n s i v e t e s t s w i t h d i f f e r e n t shapes o f compact ion probes were per formed and showed t h a t a t h r e e - b l a d e d p r o b e , p r o v i d e d w i t h h o r i z o n t a l r i b s , a c h i e v e d o p t i m a l t r a n s f e r o f v i b r a t i o n energy t o t h e s o i l . The geometry o f t h e probe w i t h a 120 degree a n g l e between t h e s t e e l b l a d e s a v o i d s decompress ion o f t h e s o i l which can o c c u r w i t h o t h e r probes d u r i n g r e t r a c t i o n , W a l l y s (1982) . The nex t major improvement o f t h e system concerned t a k i n g i n t o account t h e dynamic re sponse o f t h e s o i l d u r i n g c o m p a c t i o n . T h e o r e t i c a l a n a l y s e s and model t e s t s showed t h e im por t ance o f c h o o s i n g o p t i m a l v i b r a t i o n f r e q u e n c y , v i b r a t i o n t i m e and g r i d s p a c i n g , wh ich a r e a l l s i t e s p e c i f i c p a r a m e t e r s . T h i s can be a c h i e v e d by i n t r o d u c i n g an e l e c t r o n i c ground v i b r a t i o n m o n i t o r i n g system i n c o m b i n a t i o n w i t h the use o f a v i b r a t o r w i t h v a r i a b l e e x c i t a t i o n f r e q u e n c y . The T r i S t a r system has t h e advantage t h a t t h e v i b r a t i o n m o n i t o r i n g system p r o v i d e s i n f o r m a t i o n on ground a c c e l e r a t i o n d i r e c t l y on s i t e . T h i s o f f e r s t h e d e s i g n 2 e n g i n e e r an a d d i t i o n a l p o s s i b i l i t y o f c o n t r o l l i n g and v e r i f y i n g t h e d e n s i f i c a t i o n p r o c e s s and i t s e f f e c t i v e n e s s . T h u s , t h e most e f f i c i e n t compact ion p r o c e d u r e can be d e t e r m i n e d a t t h e s t a r t o f each p r o j e c t . The T r i S t a r concept has been used s u c c e s s f u l l y on s e v e r a l p r o j e c t s i n Europe where i t has demonstra ted i t s t e c h n i c a l e f f i c i e n c y and economy, M a s s a r s c h and Vannes te (1988) . Hence , F r a n k i d e c i d e d t o i n t r o d u c e t h e T r i S t a r sys tem on t o t h e N o r t h A m e r i c a n m a r k e t . A l t h o u g h f u r t h e r improvements o f t h e T r i S t a r method a r e p r e s e n t l y under way t o widen i t s range o f a p p l i c a t i o n s , i t was d e c i d e d t o t e s t t h e b a s i c c o n c e p t on a p r o j e c t s i t e which by o t h e r s was j u d g e d t o be m a r g i n a l l y compactable by v i b r a t o r y methods. D i s c u s s i o n s were t h e r e f o r e h e l d w i t h t h e g e o t e c h n i c a l c o n s u l t a n t t o t e s t i n i t i a l l y t h e T r i S t a r sys tem, h a v i n g as an a l t e r n a t i v e compacted s tone columns which a r e more c o s t l y , b u t a r e a w e l l p r o v e n compact ion s o l u t i o n . Thus i n c o o p e r a t i o n w i t h t h e I n - S i t u T e s t i n g G e o t e c h n i c a l R e s e a r c h Group i n C i v i l E n g i n e e r i n g a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , an e x t e n s i v e f i e l d m o n i t o r i n g and t e s t i n g programme was worked o u t . The o b j e c t i v e o f t h e r e s e a r c h was t o e v a l u a t e the per formance o f t h e T r i S t a r p r o b e . T h i s was a c h i e v e d by u s i n g v a r i o u s i n - h o u s e i n - s i t u t e s t i n g t e c h n i q u e s . The scope o f t h e r e s e a r c h i n v o l v e d i n v e s t i g a t i n g f i v e a s p e c t s o f how c o h e s i o n l e s s s o i l s a r e a f f e c t e d by the T r i S t a r p r o b e . These a r e : (1) t h e t ime e f f e c t on s t r e n g t h 3 g a i n ; (2) the zone o f i n f l u e n c e ; (3) how t h e l a t e r a l s t r e s s i s a f f e c t e d ; (4) how t h e p o r e water p r e s s u r e , measured by t h e CPTU i s a f f e c t e d ; (5) how v a r i o u s g e o t e c h n i c a l parameters a r e a f f e c t e d . 4 2 .0 REVIEW: DEEP COMPACTION OF SAND USING VIBRATORY  PROBES 2 .1 I n t r o d u c t i o n Deep compact ion o f l o o s e c o h e s i o n l e s s s o i l s i s e i t h e r r e q u i r e d t o e l i m i n a t e e x c e s s i v e s e t t l e m e n t s o r t o m i n i m i s e t h e r i s k o f l i q u e f a c t i o n caused by dynamic l o a d i n g . V i b r o c o m p a c t i o n o f c o h e s i o n l e s s s o i l s i s an e f f i c i e n t method t o i n c r e a s e s o i l d e n s i t y and s t i f f n e s s . A v a r i e t y o f dynamic methods f o r deep compact ion a r e a v a i l a b l e , such as b l a s t i n g , v i b r o c o m p a c t i o n and heavy t a m p i n g . The p r e s e n t r e v i e w d e s c r i b e s methods i n w h i c h a probe i s i n s e r t e d i n t h e ground w i t h o u t t h e a d d i t i o n o f b a c k f i l l m a t e r i a l . T h i s used t o be termed v i b r o f l o t a t i o n and the p r o b e c a l l e d a v i b r o f l o t (Steuerman, 1939) . However, the t erm v i b r o f l o t a t i o n now a p p l i e s e q u a l l y t o s tone column f o r m a t i o n i n c o h e s i v e s o i l s and t o t h e v i b r o c o m p a c t i o n o f c o h e s i o n l e s s s o i l s , whether o r no t b a c k f i l l i s added t o t h e h o l e . U s u a l l y the s o u r c e o f v i b r a t i o n i s a t t h e t o p o f the probe above t h e ground s u r f a c e , g e n e r a t i n g v e r t i c a l l y o r h o r i z o n t a l l y o s c i l l a t i n g mot ion ( M a s s a r s c h , 1986) . S o i l compact ion i s c a r r i e d out i n e i t h e r a t r i a n g u l a r o r r e c t a n g u l a r p a t t e r n and i s a c h i e v e d when the probe i s wi thdrawn g r a d u a l l y o r i n s t e p s . The d e n s i f i c a t i o n e f f e c t depends on s e v e r a l f a c t o r s : (1) s o i l t y p e , e s p e c i a l l y s o i l g r a d a t i o n and c o n t e n t o f f i n e s ; (2) degree o f s a t u r a t i o n and water t a b l e l o c a t i o n ; (3) i n i t i a l r e l a t i v e d e n s i t y ; (4) i n i t i a l i n - s i t u s t r e s s e s ; (5) s o i l s t r u c t u r e i n c l u d i n g the 5 e f f e c t o f a g i n g , s e d i m e n t a t i o n e t c . ; (6) machine c h a r a c t e r i s t i c s . 2.2 D e n s i f i c a t i o n F a c t o r s 2 . 2 . 1 S o i l Type V i b r o c o m p a c t i o n methods a r e b e s t s u i t e d f o r d e n s i f i c a t i o n o f c l e a n , c o h e s i o n l e s s s o i l s . E x p e r i e n c e has shown t h a t t h e s e methods a r e g e n e r a l l y i n e f f e c t i v e when the p e r c e n t a g e we ight o f f i n e s ( p a r t i c l e s f i n e r t h a n 0.74mm d iameter ) exceeds 20%. In t h i s case t h e p e r m e a b i l i t y o f t h e s o i l i s t oo low t o a l l o w t h e r a p i d d r a i n a g e o f excess p o r e water p r e s s u r e g e n e r a t e d by t h e a c t i o n o f the v i b r a t o r y p r o b e s . F i g u r e 1 shows t h e range o f p a r t i c l e s i z e d i s t r i b u t i o n which i s s u i t a b l e f o r d e n s i f i c a t i o n by v i b r o c o m p a c t i o n ( M i t c h e l l and K a t t i , 1981) . 2 . 2 . 2 Degree o f S a t u r a t i o n and Water T a b l e L o c a t i o n V i b r o c o m p a c t i o n methods a r e most e f f i c i e n t i n s a t u r a t e d , c o h e s i o n l e s s s o i l s . In p a r t i a l l y s a t u r a t e d s o i l s , f a l s e c o h e s i o n c r e a t e d by c a p i l l a r y f o r c e s i n c r e a s e s the e f f e c t i v e s t r e s s ( s o i l s t r e n g t h ) and t h u s t h e energy r e q u i r e d f o r s o i l c o m p a c t i o n . The c o m p a c t i o n e f f e c t i n p a r t i a l l y s a t u r a t e d s o i l s can be improved by combin ing v i b r o c o m p a c t i o n w i t h water j e t t i n g . 6 H-0 100 80 60 40 20 0 E S a n d Silt Vibrati Clay stone co lumns o o o o o o o c o o m CM o o c o o o o in CM o o o o p p o m CNJ ~- o o o o o o d in d d d d d d d d d . Figure 1 - Range of P a r t i c l e Size D i s t r i b u t i o n for Suitable Densification by Vibrocompaction, M i t c h e l l and K a t t i (1981) 7 2 . 2 . 3 I n i t i a l R e l a t i v e D e n s i t y V i b r o c o m p a c t i o n i n c r e a s e s t h e d e n s i t y o f l o o s e c o h e s i o n l e s s s o i l s . The compact ion e f f e c t i s most pronounced i n s o i l s w i t h a low i n i t i a l d e n s i t y .-2 . 2 . 4 I n i t i a l I n - s i t u S t r e s s e s The s t a t e o f i n - s i t u s t r e s s e s b e f o r e compact ion can have a s i g n i f i c a n t i n f l u e n c e on compact ion e f f i c i e n c y . In s a t u r a t e d c o h e s i o n l e s s s o i l s , compact ion i s caused by a t emporary s t a t e o f l i q u e f a c t i o n r e s u l t i n g from dynamic and c y c l i c f o r c e s . D u r i n g t h e d i s s i p a t i o n o f t h e exces s p o r e w a t e r , s o i l p a r t i c l e s a r e r e - a r r a n g e d i n t o a more dense s t a t e . The compact ion e f f e c t i s g r e a t e r i f t h e v e r t i c a l o v e r b u r d e n i s h i g h d u r i n g r e - c o n s o l i d a t i o n ( Massarsch , 1986) . T h i s means t h a t v i b r o c o m p a c t i o n i s more e f f e c t i v e a t g r e a t e r d e p t h s . As y e t t h e e f f e c t o f v i b r o c o m p a c t i o n on t h e h o r i z o n t a l s t r e s s i s no t c l e a r l y u n d e r s t o o d . However, i t i s known t h a t i t i s i n c r e a s e d from i t s o r i g i n a l K Q c o n d i t i o n . 2 . 2 . 5 I n i t i a l S o i l S t r u c t u r e V i b r o c o m p a c t i o n can a l s o have d e t r i m e n t a l e f f e c t s , e . g . on cemented s o i l s where the s o i l s t r u c t u r e can be broken down as a r e s u l t o f dynamic and c y c l i c l o a d i n g . 8 2 . 2 . 6 Machine C h a r a c t e r i s t i c s A c c o r d i n g t o Sparks (1975), machine c h a r a c t e r i s t i c s can be e x p e c t e d t o p l a y a r o l e i n t h e per formance o f a d e n s i f i c a t i o n sys tem. The i m p o r t a n t p a r a m e t e r s a r e s i z e , f r e q u e n c y , a m p l i t u d e and e c c e n t r i c f o r c e . I t has been found t h a t each o f t h e s e i s u n i q u e t o a c e r t a i n s o i l and t h e r e f o r e a f i e l d t r i a l i s r e q u i r e d t o f i n d t h e optimum v a l u e s t o a c h i e v e maximum v i b r o c o m p a c t i o n (Massarsch , 1986) . I n an i n v e s t i g a t i o n o f t h r e e machines i t was found t h a t t h e h i g h e r powered machines were c a p a b l e o f compact ing s o i l more u n i f o r m l y i n t h e v i c i n i t y o f t h e probe ( S p a r k s , 1975) . Whereas t h e lower powered l e d t o a maximum d e n s i t y o c c u r r i n g lm t o 1.5m away from t h e p r o b e . On a n a l y z i n g the r e s u l t s o f t h e s e t e s t s i t i s no t p o s s i b l e t o make f i r m c o n c l u s i o n s s i n c e t h e machines each had a d i f f e r e n t o p e r a t i n g f r e q u e n c y , power and s i z e . Morgan and Thomson (1983) a l s o i n v e s t i g a t e d t h r e e machines b u t f a i l e d t o i s o l a t e t h e i n f l u e n c e o f machine c h a r a c t e r i s t i c s . 2 .3 M o n i t o r i n g o f V i b r o c o m p a c t i o n 2 . 3 . 1 I n t r o d u c t i o n D e n s i f i c a t i o n r e s u l t i n g from v i b r o c o m p a c t i o n o c c u r s r a p i d l y and s e t t l e m e n t o f t h e ground s u r f a c e i s e s s e n t i a l l y comple ted by t h e end o f t r e a t m e n t . However, improvement i n p r o p e r t i e s such as s o i l s t i f f n e s s and s t r e n g t h may c o n t i n u e t o i n c r e a s e o v e r extended t ime p e r i o d s . T h i s e f f e c t i s p a r t i c u l a r l y pronounced i n s o i l s w i t h a h i g h c o n t e n t o f 9 f i n e s . D i f f e r e n t f i e l d methods can be used t o m o n i t o r t h e e f f e c t o f c o m p a c t i o n . 2 . 3 . 2 Methods o f M o n i t o r i n g 2 . 3 . 2 . 1 S e t t l e m e n t When no s o i l i s added d u r i n g t h e compact ion p r o c e s s , s e t t l e m e n t o f t h e ground s u r f a c e can be d i r e c t l y r e l a t e d t o t h e i n c r e a s e i n d e n s i t y o f the s o i l l a y e r s . S u r f a c e s e t t l e m e n t s can be m o n i t o r e d u s i n g s u r f a c e markers o r s e t t l e m e n t gauges . 2 . 3 . 2 . 2 P e n e t r a t i o n T e s t s The most w i d e l y used methods t o m o n i t o r compact ion e f f e c t s a r e p e n e t r a t i o n t e s t s , such as t h e S t a n d a r d P e n e t r a t i o n T e s t (SPT) , t h e s t a t i c cone p e n e t r a t i o n t e s t (CPT) o r t h e dynamic cone p e n e t r a t i o n t e s t . A new p e n e t r a t i o n t e s t , t h e F l a t D i l a t o m e t e r T e s t (DMT) i n t r o d u c e d by M a r c h e t t i (1980) i s a l s o u s e d . A d i r e c t c o n v e r s i o n o f p e n e t r a t i o n r e s i s t a n c e t o r e l a t i v e d e n s i t y may, however, be u n c e r t a i n because p e n e t r a t i o n r e s i s t a n c e can depend on many f a c t o r s i n a d d i t i o n t o d e n s i t y . F u r t h e r m o r e , p e n e t r a t i o n r e s i s t a n c e i s u s u a l l y measured a t i n d i v i d u a l l o c a t i o n s between compact ion p o i n t s , which may not r e p r e s e n t the average d e n s i t y o f t h e s o i l d e p o s i t . P r e s s u r e m e t e r T e s t s and Screw P l a t e T e s t s a r e used i n c r e a s i n g l y and g i v e more s p e c i f i c 10 i n f o r m a t i o n on s o i l s t i f f n e s s as w e l l as on u l t i m a t e s t r e n g t h . 2 . 3 . 2 . 3 S e i s m i c T e s t s S e i s m i c f i e l d t e s t s , such as c r o s s - h o l e and down-hole t e s t s , have become t h e s t a n d a r d t e c h n i q u e s f o r t h e i n - s i t u d e t e r m i n a t i o n o f s h e a r wave v e l o c i t y . I n a s e i s m i c t e s t , t h e p r o p a g a t i o n o f s h e a r waves i s measured w i t h g r e a t a c c u r a c y i n t h e h o r i z o n t a l o r v e r t i c a l d i r e c t i o n o v e r a d i s t a n c e o f s e v e r a l m e t r e s . T h i s t e s t i n v o l v e s a l a r g e r s o i l volume t h a n do p e n e t r a t i o n t e s t s and maybe more r e p r e s e n t a t i v e o f t h e average compact ion e f f e c t . The r e s u l t o f s e i s m i c t e s t s can be d i r e c t l y r e l a t e d t o the change o f s h e a r modulus . Shear wave v e l o c i t i e s a r e a l s o e s s e n t i a l f o r s e i s m i c d e s i g n p u r p o s e s . A new t e s t , c a l l e d t h e s e i s m i c cone p e n e t r a t i o n t e s t ( S C P T ) , has been d e v e l o p e d (Campanel la e t a l , 1986) . T h i s t e s t c o n s i s t s o f a s m a l l rugged v e l o c i t y se ismometer i n c o r p o r a t e d i n t o an e l e c t r o n i c cone p e n e t r o m e t e r . The c o m b i n a t i o n o f t h e s e i s m i c down-hole method and t h e CPT l o g g i n g p r o v i d e an e x t r e m e l y r a p i d , r e l i a b l e and economic means o f d e t e r m i n i n g s t r a t i g r a p h i c , s t r e n g t h and modulus i n f o r m a t i o n i n one s o u n d i n g . F i n a l l y , d e n s i t y m e t e r s , such as n u c l e a r p r o b e s can a l s o be used t o check t h e v a r i a t i o n o f s o i l d e n s i t y i n a b o r e h o l e . 11 2 . 3 . 2 . 4 R e a l Time M o n i t o r i n g The s t a t e o f d e n s i f i c a t i o n i s f r e q u e n t l y e s t i m a t e d d u r i n g compact ion by m o n i t o r i n g t h e power i n p u t t o the d r i v e motor . A c c o r d i n g t o D ' A p p o l o n i a (1953)" t h e power i n p u t r e a c h e s a maximum when t h e maximum s o i l d e n s i t y has been r e a c h e d . However, t h e t e c h n i q u e r e q u i r e s an e x p e r i e n c e d o p e r a t o r and does no t a c c o u n t f o r compact ion d i s c r e p a n c i e s . The above has been r e f u t e d by model s t u d i e s by M e t z g e r and K o e r n e r (1975) . They found t h a t maximum power consumpt ion o c c u r r e d d u r i n g c o m p a c t i o n , no t as g e n e r a l l y b e l i e v e d from f i e l d e x p e r i e n c e , where i t i s found t h a t maximum power consumpt ion accompanies maximum c o m p a c t i o n . Hence, D ' A p p o l o n i a ' s method appears t o be i n d o u b t . A n o t h e r p o s s i b l e method o f c o n t r o l has been r e p o r t e d by Morgan and Thomson (1981), i n which t h e probe v i b r a t i o n i s measured w i t h t r a n s d u c e r s . Measurements a r e made w i t h a c c e l e r o m e t e r s mounted i n t h e t i p o f t h e p r o b e . I t was found t h a t the h o r i z o n t a l a m p l i t u d e o f t h e probe d e c r e a s e d w i t h i n c r e a s i n g sand d e n s i t y , as found from subsequent p e n e t r a t i o n t e s t s . T h i s method i s p o t e n t i a l l y v e r y r e l i a b l e as i t i s a d i r e c t measurement o f ground r e s p o n s e . An a l t e r n a t i v e method i s t o measure t h e v i b r a t i o n s caused by t h e probe u s i n g one and t h r e e d i m e n s i o n a l geophones (Massarsch and V a n n e s t e , 1988) . The A . C . v o l t a g e g e n e r a t e d i s t r a n s f o r m e d i n t o a r o o t mean s q u a r e (R.M.S.) v e l o c i t y . T h i s can be r e l a t e d t o t h e d e n s i f i c a t i o n 12 o b t a i n e d , i . e . t h e h i g h e r t h e R . M . S . v e l o c i t y , t h e h i g h e r t h e compact ion e f f e c t . Hence, i n f o r m a t i o n on t h e v i b r a t i o n f r e q u e n c y , g r i d s p a c i n g and v i b r a t i o n t i m e can be d e t e r m i n e d on s i t e and used t o o p t i m i s e t h e compact ion p r o c e d u r e . 2 .4 H i s t o r y The improvement o f s o i l s a t depth u s i n g a v i b r a t i n g probe was f i r s t per formed i n Germany o v e r f i f t y y e a r s ago, and r e p o r t e d i n t h e E n g l i s h language by Steuerman (1939) . He d e s c r i b e d what was t o become t h e most w i d e l y used deep improvement p r o c e s s namely, v i b r o f l o t a t i o n . The t e c h n i q u e was i n i t i a l l y used i n o n l y c o h e s i o n l e s s s o i l s , and c o u l d be per formed w i t h o u t i m p o r t e d b a c k f i l l . As s u c h , i t was a t r u e v i b r o c o m p a c t i o n t e c h n i q u e . S u b s e q u e n t l y c o a r s e sand o r g r a v e l b a c k f i l l was added t o t h e probe h o l e . H e n c e , t h e t e c h n i q u e was adapted f o r use i n c o h e s i v e s o i l s , t h u s t h e v i b r o r e p l a c e m e n t p r o c e s s was e s t a b l i s h e d . 2 .5 V i b r o c o m p a c t i o n Methods U s i n g T o p d r i v e V i b r a t o r s 2 . 5 . 1 I n t r o d u c t i o n These methods a r e c h a r a c t e r i s e d by t h e i n s e r t i o n o f a c y l i n d r i c a l o r c r o s s - s h a p e d probe i n t o t h e g r o u n d . A t the t o p o f the p r o b e , a v i b r a t o r g e n e r a t e s e i t h e r v e r t i c a l o r t o r s i o n a l , o s c i l l a t i n g m o t i o n . The probe i s e i t h e r pushed, v i b r a t e d o r j e t t e d i n t o t h e ground and t h e compact ion i s a c h i e v e d d u r i n g t h e s t e p - w i s e w i t h d r a w i n g o f t h e probe t o 13 t h e s u r f a c e . Ground t r e a t m e n t depths o f 15m can be r o u t i n e l y a c h i e v e d 2 . 5 . 2 The F o s t e r Probe The F o s t e r probe was d e v e l o p e d i n t h e U . S . A . , and uses a v i b r o - p i l e d r i v e r on t o p o f a 760mm d i a m e t e r open t u b e . The probe i s 3 t o 5 m l o n g e r t h a n t h e d e s i r e d p e n e t r a t i o n d e p t h and t h e u n i t o p e r a t e s a t a f r e q u e n c y o f 15 Hz and the v e r t i c a l a m p l i t u d e o f mot ion i s 10 t o 25mm. About 15 p r o b e s p e r h o u r can be comple ted a t s p a c i n g s o f 1 t o 3m. 2 . 5 . 3 . The V i b r o Wing Probe The V i b r o Wing probe was d e v e l o p e d f o r deep compact ion o f n a t u r a l and dredged c o h e s i o n l e s s s o i l s , M a s s a r s c h and L i n d b e r g (1986) . F o r t h i s a p p l i c a t i o n a heavy v i b r a t o r (mass 7 m e t r i c tonnes) i s a t t a c h e d t o t h e t o p o f a 15m l o n g s t e e l r o d , which i s p r o v i d e d w i t h 0.8m l o n g wings , spaced 0.5m a p a r t . The v i b r a t o r y hammer i s o p e r a t e d from a p i l i n g r i g , which i s n o r m a l l y used f o r t h e i n s t a l l a t i o n o f p r e - f a b r i c a t e d c o n c r e t e p i l e s . The p u l l - o u t r e s i s t a n c e o f t h e probe can be m o n i t o r e d d u r i n g t h e compact ion p r o c e s s by a l o a d c e l l , p l a c e d a t t h e t o p o f the r i g . The f r e q u e n c y o f the v i b r a t o r can be v a r i e d t o f i t t h e c o n d i t i o n s a t a p a r t i c u l a r s i t e . The probe i s d r i v e n down t o the depth t o be compacted. I f n e c e s s a r y , t h e d r i v i n g can be h e l p e d by j e t t i n g a t the 14 bottom o f t h e s t e e l r o d . The s o i l i s t h e n v i b r a t e d v e r t i c a l l y u n t i l t h e r e q u i r e d degree o f c o m p a c t i o n has been a c h i e v e d . The f r e q u e n c y o f v i b r a t i o n i s t y p i c a l l y 20Hz. The d u r a t i o n o f v i b r a t i o n and r a t e o f w i t h d r a w a l o f the p r o b e depends m a i n l y on t h e p e r m e a b i l i t y o f t h e s o i l , the d e p t h o f t h e d e p o s i t and t h e s p a c i n g between compact ion p o i n t s . 2 . 5 . 4 The V i b r o Rod Probe The V i b r o Rod probe i s s i m i l a r t o t h e F o s t e r probe but u t i l i s e s a s t e e l r o d p r o v i d e d w i t h s h o r t r i b s , w i t h a d i a m e t e r o f 0.5m and was d e v e l o p e d i n J a p a n , u s i n g a v i b r a t i n g p i l e d r i v i n g hammer, S a i t o (1977) . A second probe d e s c r i b e d by S a i t o (1977), c o m p r i s e s a c l o s e d , cone t i p p e d p i p e , 300mm i n d i a m e t e r w i t h , 100mm h i g h t e t r a h e d r a spaced o v e r t h e bottom 4m o f the p r o b e . 2 . 5 . 5 The M y t i l u s Probe T h i s i s a l a r g e s c a l e a p p a r a t u s i n t e n d e d f o r o f f s h o r e sand d e n s i f i c a t i o n and was used f o r t h e B a r r a g e P r o j e c t i n H o l l a n d , and i s d e s c r i b e d by D a v i e s e t a l . (1981) . The v i b r a t i n g probe c o n s i s t s o f a tube w i t h t w e l v e r a d i a l f i n s , w i t h a d i a m e t e r o f 2.1m. The probe i s v i b r a t e d v e r t i c a l l y from t h e t o p o f t h e t u b e , a t 25 H z . F o u r such v i b r a t o r s , spaced a t 6.5m can be d e p l o y e d s i m u l t a n e o u s l y from a p o n t o o n , a l l o w i n g a zone up t o 26m wide and 15m i n depth t o be d e n s i f i e d . 15 2 . 5 . 6 The T r i S t a r Probe The F r a n k i company o f B e l g i u m , has d e v e l o p e d a deep v i b r o c o m p a c t i o n method u s i n g a s t a r shaped p r o b e , which i s i n s e r t e d i n the ground u s i n g a heavy v i b r a t o r . The s t a r shaped probe was chosen t o e l i m i n a t e as much p l u g g i n g as p o s s i b l e i n t h e c o r n e r s between t h e p l a t e s o f t h e p r o b e . The p r o c e s s i s v e r y s i m p l e and f a s t , ( W a l l y s , 1982) . I t c o n s i s t s o f t h r e e l o n g s t e e l p l a t e s , 20mm t h i c k by 500mm w i d e , welded t o g e t h e r a t an a n g l e o f 1 2 0 ° . The probe can be up t o 20m l o n g . S m a l l p l a t e s g e n e r a l l y 10mm x 50mm x 300mm a r e welded t o each s i d e o f t h e p l a t e s a t two metre i n t e r v a l s which h e l p t r a n s f e r t h e v i b r a t i o n energy t o the s o i l . The probe i s a t t a c h e d t o a heavy p i l i n g v i b r a t o r and v i b r a t e d v e r t i c a l l y i n t o t h e s o i l . I t was f i r s t used i n 1977 and has s i n c e been e x t e n s i v e l y used f o r u n d e r - w a t e r and onshore deep compact ion o f c o h e s i o n l e s s s o i l s . 2 . 5 . 7 The Phoenix Probe The equipment compr i se s a probe which i s c a p a b l e o f g e n e r a t i n g l a t e r a l v i b r a t i o n and s i m u l t a n e o u s pumping o f w a t e r . The probe i s a t o r p e d o shaped u n i t s i m i l a r t o a v i b r o f l o t a t i o n p r o b e , b u t w i t h t h e a d d i t i o n o f a d r a i n a g e s e c t i o n b e h i n d the t i p . The probe i s v i b r a t e d w i t h a i r , a t 100 p s i , conveyed by custom b u i l t d r i l l p i p e s t o t h e t i p which houses an a i r motor . T h i s r o t a t e s an e c c e n t r i c mass on a v e r t i c a l a x i s , hence d e v e l o p i n g h o r i z o n t a l v i b r a t i o n . 16 D r a i n a g e i s a c h i e v e d when t h e exhaust a i r p a s s e s t h r o u g h a v e n t u r i hence c a u s i n g a s u c t i o n . T h i s s u c t i o n i s a p p l i e d a c r o s s t h e d r a i n a g e s c r e e n , t h u s s u c k i n g i n w a t e r , which i s t h e n c a r r i e d t o t h e s u r f a c e by t h e a i r . I n o r d e r t o a v o i d c l o g g i n g , t h e s c r e e n must be s i z e d t o s u i t t h e s o i l c h a r a c t e r i s t i c s . The probe i s o p e r a t e d from a s t a n d a r d t o p - d r i v e r o t a r y d r i l l r i g and i s lowered i n t o t h e s o i l on a custom d e s i g n e d d r i l l s t r i n g . 2 .6 E x p e c t e d R e s u l t s T h o r b u r n (1975) p r o p o s e d g u i d e l i n e s t o e s t i m a t e the l i k e l y degree o f improvement a c h i e v a b l e . However, i t i s cus tomary t o p e r f o r m a t r i a l a t t h e s i t e o f p r o p o s e d s o i l improvement t o e s t a b l i s h t h e optimum c o n f i g u r a t i o n o f improvement p r o b e s . Such d e s i g n r e l a t i o n s h i p s w i l l depend on s o i l and machine c h a r a c t e r i s t i c s which w i l l v a r y between s i t e s . 2 .7 C o n c l u s i o n s T h e r e e x i s t s a s i g n i f i c a n t body o f i n f o r m a t i o n i n the g e o t e c h n i c a l l i t e r a t u r e d e s c r i b i n g e x p e r i e n c e w i t h v i b r o c o m p a c t i o n . I t c o n c e n t r a t e s p r i m a r i l y on the a b i l i t y o f a g i v e n t e c h n i q u e t o p e r f o r m d e n s i f i c a t i o n , i . e . s o i l t y p e , probe s p a c i n g and p a t t e r n which r e l a t e p r i m a r i l y t o p e r f o r m a n c e . However, t h e r e i s l i t t l e i n f o r m a t i o n w i t h r e g a r d t o t h e s o i l mechanics a s p e c t o f t h e d e n s i f i c a t i o n 17 p r o c e s s , such as t h e t ime dependency o f t h e p r o c e s s , the e f f e c t on t h e i n - s i t u l a t e r a l s t r e s s . A l s o , the p o r e water p r e s s u r e b e h a v i o u r d u r i n g t h e d e n s i f i c a t i o n p r o c e s s has y e t t o be a d e q u a t e l y d e s c r i b e d . F i n a l l y t h e e f f e c t s o f o p e r a t i n g parameters which i n c l u d e , f r e q u e n c y , a m p l i t u d e , power i n p u t and equipment d i m e n s i o n s a r e s t i l l u n c l e a r . 18 3 .0 PROJECT DESCRIPTION T h i s t h e s i s i n v e s t i g a t e s t h e d e n s i f i c a t i o n p r o j e c t e x e c u t e d i n F e b r u a r y 1988 on t h e Gray Beverage I n c . s i t e a t A n n a c i s I s l a n d , B . C . , Canada. Development o f t h e s i t e i n v o l v e d t h e c o n s t r u c t i o n o f a m a n u f a c t u r i n g s t o r a g e b u i l d i n g and a f l e e t maintenance b u i l d i n g n e a r t h e A n n a c i s c h a n n e l . Because o f t h e l i q u e f a c t i o n p o t e n t i a l o f t h e s u b - s o i l d u r i n g s t r o n g e a r t h q u a k e s , i t was judged t h a t t h e proposed b u i l d i n g s c o u l d s u f f e r major damage d u r i n g a s t r o n g e a r t h q u a k e . Thus t h e g e o t e c h n i c a l c o n s u l t a n t f o r t h e p r o j e c t , Cook P i c k e r i n g and Doy le L t d . , p r o p o s e d s o i l compact ion t o i n c r e a s e t h e l a t e r a l s t a b i l i t y o f t h e a r e a s l o p i n g towards the F r a s e r R i v e r . As t h e c o n s t r u c t i o n s i t e i s u n d e r l a i n by t h i c k d e l t a i c and a l l u v i a l d e p o s i t s , t h e g e o t e c h n i c a l c o n s u l t a n t s s p e c i f i e d t h e d e n s i f i c a t i o n o f a c o n t i n u o u s s t r i p a r e a between t h e r i v e r c h a n n e l and t h e p r o p o s e d b u i l d i n g s i t e . T h i s d e n s i f i e d s t r i p a r e a would p r o v i d e a s t a b i l i z i n g "dyke" and t h e g r a n u l a r f i l l and c l a y e y s i l t l a y e r s would t h e n be a c t i n g as a " r a f t " , f l o a t i n g on t o p o f the l i q u e f i e d s o i l u n d e r n e a t h . M a j o r h o r i z o n t a l movements o f t h e l i q u e f i e d s o i l would be reduced by t h e "dyke", t h e r e b y p r e v e n t i n g major damage t o t h e b u i l d i n g s . FRANKI CANADA L t d . was awarded t h e d e n s i f i c a t i o n p r o j e c t based on t h e T r i S t a r compact ion method b e i n g a b l e t o a c h i e v e t h e r e q u i r e d d e n s i f i c a t i o n . I n o r d e r t o e s t a b l i s h 19 t h e o p t i m a l compact ion p r o c e d u r e ( v i b r a t o r f r e q u e n c y , v i b r a t i o n t i m e and g r i d s p a c i n g ) , a s e r i e s o f d e n s i f i c a t i o n t r i a l s were per formed b e f o r e t h e s t a r t o f t h e a c t u a l p r o j e c t . R e s u l t s o f t h e s e t e s t s , which- i n c l u d e d measurements o f ground v i b r a t i o n s , p o r e water p r e s s u r e and s e t t l e m e n t s as w e l l as cone and s t a n d a r d p e n e t r a t i o n t e s t s b e f o r e and a f t e r d e n s i f i c a t i o n were c a r r i e d out by F r a n k i and ConeTec and e v a l u a t e d by F r a n k i . These t r i a l s were e x e c u t e d from F e b r u a r y 3 r d t h r o u g h 12 th , 1988, a f t e r which t h e p r o d u c t i o n phase o f t h e p r o j e c t t o o k p l a c e d u r i n g the second h a l f o f F e b r u a r y 1988. F u r t h e r t e s t i n g and e v a l u a t i o n was c a r r i e d out by ConeTec and F r a n k i d u r i n g t h i s s t a g e t o check the T r i S t a r p e r f o r m a n c e . T h e r e a f t e r , U . B . C . c a r r i e d out i t s t e s t i n g programme which l a s t e d u n t i l September, 1988. 20 4 .0 RESEARCH S I T E 4 .1 I n t r o d u c t i o n F i e l d t e s t s were c a r r i e d out t o i n v e s t i g a t e t h e F r a n k i T r i S t a r d e n s i f i c a t i o n equipment . The s i t e i s l o c a t e d on A n n a c i s I s l a n d , V a n c o u v e r , B . C . The s i t e b e l o n g s t o Gray Beverage I n c . who were b u i l d i n g a new f a c t o r y complex . The t e s t i n g was c a r r i e d out d u r i n g t h e c o n s t r u c t i o n o f t h i s new f a c t o r y and was c u r t a i l e d when t h e t e s t a r e a was c o v e r e d w i t h b l a c k t o p . 4.2 R e g i o n a l Geo logy A n n a c i s I s l a n d i s p a r t o f t h e p o s t g l a c i a l F r a s e r R i v e r D e l t a and i s s i t u a t e d i n the upper r e a c h o f t h e I s l a n d Arm o f t h e F r a s e r R i v e r ( F i g u r e 2 ) . B lunden (1973) i d e n t i f i e s t h e F r a s e r R i v e r D e l t a r e g i o n sed iments as marine d e l t a i c d e p o s i t s t h a t have formed upon b a s a l l a y e r s . These l a y e r s have undergone i s o s t a t i c rebound f o r r o u g h l y 11,000 y e a r s a t a r a t e g r e a t e r t h a n t h e r a t e o f r e c e n t ( i . e . p o s t g l a c i a l ) mar ine t r a n s g r e s s i o n . The t o t a l t h i c k n e s s o f d e l t a i c d e p o s i t s i s r o u g h l y 200 m. F u r t h e r , t h e d e l t a has been above sea l e v e l a p p r o x i m a t e l y 8,000 y e a r s when t h e sea l e v e l was about 10m below p r e s e n t l e v e l s (B lunden , 1973) . The s u r f i c i a l geo logy o f t h e A n n a c i s I s l a n d r e g i o n i s t y p i c a l o f a t i d e dominated d e l t a . T h e r e i s a p r e v a l e n t t h i n d e p o s i t o f c l a y s and s i l t s mixed w i t h some o r g a n i c s 21 F i g u r e 2 - F r a s e r R i v e r D e l t a G e o l o g y , B l u n d e n , (1973) t h a t have been l a i d down i n a q u i e s c e n t swamp o r marsh e n v i r o n m e n t . Below t h i s t o p c r u s t i s a sequence o f bedded sandy s i t e s w i t h v a r i o u s seams o f s a n d , s i l t , c l a y and minor o r g a n i c s . Because o f t h e n o n - u n i f o r m i t y o f t h e zone below t h e top c r u s t , t h e d e p o s i t i o n a l h i s t o r y most l i k e l y r e p r e s e n t s a t u r b u l e n t env ironment b e i n g a s s o c i a t e d w i t h the t i d a l f o r c e s . The base o f t h i s s u c c e s s i o n i s composed o f c l a y s and s i l t s which were l a i d down i n a much more q u i e s c e n t m a r i n e e n v i r o n m e n t . 4.3 S i t e D e s c r i p t i o n The s i t e o f i n v e s t i g a t i o n f o r t h i s s t u d y i s a t t h e n o r t h s i d e o f A n n a c i s I s l a n d , which i s s i t u a t e d i n t h e upper r e a c h o f t h e F r a s e r R i v e r I s l a n d Arm, shown i n F i g u r e 2. A s i t e p l a n ( F i g u r e 3) shows t h e l o c a t i o n o f t h e U . B . C . t e s t a r e a s , t e s t s c a r r i e d out by ConeTec and o t h e r r e l e v a n t d e t a i l s . The U . B . C . t e s t i n g l o c a t i o n s a r e shown i n F i g u r e 4. The ground water t a b l e a t t h e s i t e v a r i e s w i t h t i d a l f l u c t u a t i o n and i s t y p i c a l l y found a t 2 t o 4m below ground l e v e l . The s i t e i s e s s e n t i a l l y f l a t and t h e e l e v a t i o n i s a p p r o x i m a t e l y 4.7m above mean sea l e v e l . F i g u r e 3 - G e n e r a l S i t e P l a n , G r a y B e v e r a g e S i t e 20 I 5 o • t tt J * o * 012 on Ot*t otr A/ •7~esr flfttfl ( SCO*00 o uec cprws * UBC PMTs A UBC LSCPrU's • FRflNk I CPrWs S i t e P l a n o f T e s t L o c a t i o n s i n U . B . C . T e s t i n g A r e a 25 A summary o f t h e s o i l p r o f i l e a t t h e s i t e i s as f o l l o w s : Depth (m) G e n e r a l S o i l Type 0 - 2 .5 brown SAND F I L L , dense 2 .5 - 5 .0 f i r m brown c l a y e y S I L T , o r g a n i c s 5 .0 - 11 .5 g r e y medium SAND, some S I L T l a y e r s , medium dense 11 .5 - s o f t g r e y c l a y e y S I L T T h i s p r o f i l e was d e t e r m i n e d from s e v e r a l s o u r c e s , namely: 1) Cook P i c k e r i n g & Doy le L t d . s i t e i n v e s t i g a t i o n u s i n g b o r e h o l e s . 2) ConeTec s i t e i n v e s t i g a t i o n u s i n g C P T U ' s 3) U . B . C . s i t e i n v e s t i g a t i o n u s i n g C P T U ' s , DMT, and L S C T P U ' s The medium dense sand from 5.0m t o 11.5m was t h e r e a s o n f o r d e n s i f i c a t i o n as i t was f e l t t h a t i t would l i q u e f y d u r i n g a s t r o n g e a r t h q u a k e . W i t h r e g a r d t o t h e t h i n s i l t l a y e r s i n t h e medium dense sand from 5.0m t o 11.5m t h e s e were judged t o be o f l i m i t e d l a t e r a l e x t e n t based on t h e CPTU r e s u l t s . In a l l , t h r e e t e s t i n g a r e a s were u s e d , c o n s i s t i n g o f one t r e a t e d a r e a and two v i r g i n a r e a s ( F i g u r e 3 ) . The t r e a t e d a r e a i s l o c a t e d a t the c e n t r e l i n e o f the d e n s i f i c a t i o n a t t h e 500 f o o t c h a i n a g e l i n e and i s named C L 500 + 00. The f i r s t v i r g i n a r e a i s 90 f e e t s o u t h o f C L 500 + 00 and i s named V i r g i n A r e a #1. The second v i r g i n a r e a i s l o c a t e d 200 f e e t e a s t o f C L 500 + 00. T h e r e were two v i r g i n areas as i t was thought t h a t V i r g i n A r e a #1 may have been a f f e c t e d by t h e p r e - l o a d f o r t h e f a c t o r y f o u n d a t i o n s , hence V i r g i n A r e a #2 was i n v e s t i g a t e d . T h i s showed no e v i d e n c e o f t h e s u s p e c t e d prob lem i n the f i r s t a r e a , t h u s V i r g i n A r e a #1 was used as t h e bench mark s i n c e i t more c l o s e l y re sembled t h e s o i l p r o f i l e a t t e s t a r e a C L 500 + 00. V i r g i n A r e a #1 was used f o r a l l the t e s t s e x c e p t the CPTU as a CPTU t e s t had been c a r r i e d out b e f o r e d e n s i f i c a t i o n on t h e c e n t r e l i n e . 27 5.0 SOIL INVESTIGATIONS 5 .1 F r a n k i T e s t i n g I n i t i a l l y a l i m i t e d number o f s t a n d a r d p e n e t r a t i o n t e s t s (SPT) were per formed u s i n g t h e "Donut" hammer, i n d i f f e r e n t l o c a t i o n s o f t h e c o n s t r u c t i o n s i t e . However, o n l y 3 S P T ' s were l o c a t e d nearby t h e s t r i p a r e a t o be d e n s i f i e d . M o r e o v e r , i n s p e c t i o n o f samples from some o f t h e S P T ' s i n d i c a t e d t h e p r e s e n c e o f t h i n s i l t l a y e r s i n t h e sand t o be d e n s i f i e d , which a r e t y p i c a l o f t h e d e l t a i c d e p o s i t s o f t h e F r a s e r R i v e r . T h e r e f o r e , i t was judged n e c e s s a r y t o c o n d u c t a second s o i l e x p l o r a t i o n phase , c o n c e n t r a t i n g on t h e s t r i p a r e a t o be compacted, b e f o r e d e n s i f i c a t i o n work c o u l d s t a r t . P i e z o c o n e t e s t s were a l s o per formed as t h e y p r o v i d e d e t a i l e d , c o n t i n u o u s d iagrams showing s t r a t i f i c a t i o n and s o i l s t r e n g t h . The C P T U ' s showed t h e e x i s t e n c e o f a number o f t h i n , l o c a l s i l t l a y e r s . N e g a t i v e excess p o r e water p r e s s u r e , measured b e h i n d t h e t i p , was observed d u r i n g p e n e t r a t i o n o f t h e s e s i l t l a y e r s , s u g g e s t i n g t h a t t h e y were dense and thus l e s s prone t o l i q u e f a c t i o n . As some o f t h e CPTU's were l o c a t e d nex t t o S P T s , i t was p o s s i b l e t o check t h e c o r r e l a t i o n between cone r e s i s t a n c e (q_) and b lowcounts (N), F i g u r e 5. T h i s was done u s i n g a r e l a t i o n s h i p p r o p o s e d by R o b e r t s o n and Campane l la (1983) w h i c h t a k e s i n t o account t h e mean g r a i n s i z e ( D 5 Q ) and i s shown i n F i g u r e 6. CPT1 =SPT2 CPT2 = SPT7 CPU=SPT3 coc K M I W nucTin (utio O K K M I « m c n i mn cat touts FRICTION uno i 0 H ( / ) • 1 0 0 0 H < / ) • 1 0 0 0 K ( / ) • 1 0 0 | | |—I—I l I I l I I I j | I I I i I I i — I — l - H BLOWCOUHT B L 0 V C 0 U N T B L 0 W C 0 0 H T F i g u r e 5 - C o r r e s p o n d i n g CPTU and SPT r e s u l t s B e f o r e D e n s i f i c a t i o n , Massarsch and Vannes te (1988) 00 29 q : cone res is tance (bar ) ; N : blow count (blows/foot) CLAY 10 z < CLAYEY SOTS SANDY SILT A SILTY CLAY • SILT SILTY SANO SANO / 1 ? I i -"* A 0 0.001 0.01 0.1 MEAN GRAIN SIZE, D M,mm 1.0 F i g u r e 6 - I n f l u e n c e o f G r a i n S i z e on q c / N r a t i o , R o b e r t s o n and C a m p a n e l l a (1983) G r a i n s i z e d i s t r i b u t i o n c u r v e s from samples o f the sand l a y e r t o be d e n s i f i e d i n d i c a t e d t h a t D 5 Q i s about 0.3mm, s u g g e s t i n g a q _ / N f a c t o r o f 5 (q_ i n b a r ) . T h i s does not agree w i t h t h e a c t u a l d a t a as i t i s t o o h i g h . A v a l u e o f 2 .5 i s r e q u i r e d . T h i s i s p r o b a b l y due t o t h e SPT not b e i n g c a l i b r a t e d f o r energy . 5.2 U . B . C . T e s t i n g 5 . 2 . 1 S o i l P r o f i l e The most p o p u l a r method o f s o i l t y p e i d e n t i f i c a t i o n from a CPTU t e s t uses t h e cone b e a r i n g and f r i c t i o n r a t i o ( r a t i o o f s l e e v e f r i c t i o n s t r e s s d i v i d e d by cone b e a r i n g s t r e s s ) . R o b e r t s o n e t a l (1986) p r o d u c e d t h e s o i l i n t e r p r e t a t i o n c h a r t shown i n F i g u r e 7. T h i s u t i l i z e s t h e s e parameters and i s based on a c o m b i n a t i o n o f U . B . C . e x p e r i e n c e and e a r l i e r work by Douglas and O l s e n (1981) . T h u s , F i g u r e 7 was used t o a s s i s t i n t h e i n t e r p r e t a t i o n o f s o i l t y p e s from t h e CPTU p r o f i l e o f 104CPT3 ( C L 500 + 00 b e f o r e t rea tment ) . The r e s u l t i n g s o i l p r o f i l e i s i n d i c a t e d i n F i g u r e 8. R e f e r r i n g t o F i g u r e 8 t h e p r o f i l e i n d i c a t e s f o u r d i s t i n c t s o i l t y p e s . Below a dense sand f i l l w h i c h ends a t 2.4m and u n t i l 5.0m t h e cone b e a r i n g peaks and t r o u g h s , as does t h e f r i c t i o n r a t i o and pore p r e s s u r e , a l l o f which i n d i c a t e a s i l t w i t h sand l e n s e s . From 5.0m t o 11.5m O I 2 3 4 5 O F r i c t i o n R a t i o C O 7 • Zone S o i l Behaviour Type 1 sensitive fine grained 2 organic material 3 clay 4 c i l t y clay to clay 5 clayey s i l t to s i l t y clay 6 sandy s i l t to clayey s i l t 7 s i l t y sand to sandy s i l t S sand to s i l t y sand 9 sand 1 0 gravelly sand to sand 1 1 very s t i f f fine grained 1 2 sand to clayey sand * overconsolidated or cemented F i g u r e 7 - S o i l Beha v iour Type C l a s s i f i c a t i o n C h a r t , R o b e r t s o n e t a l (1986) UBC IN S I T U T E S T I N G Site Location! ConaTac CPT Data • On Si to Loci FRANK I ANN AC IS . Cona Uoodi 01/28/B7 14i5S 10 TON HT NO. 244 F i l a i 104cpt3.dat Connartsi 68104 CPT-3 CONE BEARING Oc (bar) SLEEVE FRICTION FRICTION RATIO PORE PRESSURE DIFFERENTIAL P.P. INTERPRETED (bar) Rf ( » U (•. or >at«r> Ratio AU/Oe PROFILE VI Ql L 4J 0) E a. ui • MBCXUM Dapth Increment i .05 « Max Dapth i 13.43 • F i g u r e 8 - CPTU P r o f i l e 104CPT3 Showing I n t e r p r e t e d S o i l P r o f i l e u to p o r e p r e s s u r e s a r e h y d r o s t a t i c , t h e f r i c t i o n r a t i o remains c o n s t a n t and t h e cone b e a r i n g g r a d u a l l y i n c r e a s e s . T h i s i s i n t e r p r e t e d as n a t u r a l l y d e p o s i t e d F r a s e r R i v e r s a n d . From t h e i n i t i a l s i t e i n v e s t i g a t i o n t h i s sand was found t o be medium dense . T h e r e a f t e r , t h e cone b e a r i n g f a l l s o f f s i g n i f i c a n t l y t o a s t eady s t a t e , w h i l e t h e f r i c t i o n r a t i o i n c r e a s e s t h e n become s t eady and t h e p o r e p r e s s u r e s i n c r e a s e t o a l a r g e p o s i t i v e v a l u e . T h i s i s i n t e r p r e t e d as a c l a y e y s i l t . 6.0 DENSIFICATION REQUIREMENTS The l o c a t i o n and the s i z e o f the a r e a t o be d e n s i f i e d a r e shown i n F i g u r e 3. A c c o r d i n g t o t h e c o n s u l t a n t s s p e c i f i c a t i o n s , d e n s i f i c a t i o n was t o be a t t a i n e d i n the medium dense sand l a y e r from 5.0m t o 10 metres and was t o be checked by SPT u s i n g t h e "Donut" hammer. As d e n s i f i c a t i o n was a l s o checked by means o f CPTU ' s , the se minimum blowcount v a l u e s (N) were t h e r e f o r e c o n v e r t e d i n t o cone r e s i s t a n c e v a l u e s (q ) . 35 7 .0 TRI STAR VIBROCOMPACTION EQUIPMENT AND METHOD S a t u r a t e d , l o o s e s o i l s can be d e n s i f i e d u s i n g v i b r o c o m p a c t i o n . However, e x p e r i e n c e has shown t h a t t h i s d e n s i f i c a t i o n method i s o n l y e f f i c i e n t i f t h e g r a i n s i z e d i s t r i b u t i o n o f t h e s o i l s a t i s f i e s t h e c r i t e r i a as g i v e n by M i t c h e l l and K a t t i (1981), see F i g u r e 1. Based on the CPTU r e s u l t s i t was judged t h a t t h e t h i n s i l t l a y e r s i n the a l l u v i a l sand were o n l y o f l i m i t e d l a t e r a l e x t e n t and would t h u s no t s i g n i f i c a n t l y e f f e c t t h e compact ion e f f i c i e n c y . The T r i S t a r probe ( F i g u r e 9) i s i n s e r t e d v e r t i c a l l y i n t o t h e s o i l u s i n g a heavy v i b r a t o r , M a s s a r s c h (1986) . I t c o n s i s t s o f t h r e e l o n g s t e e l p l a t e s , a p p r o x i m a t e l y 20mm t h i c k and 500mm wide , welded t o each o t h e r a t an a n g l e t o 1 2 0 ° . S m a l l r i b s a r e welded a l o n g b o t h s i d e s o f each p l a t e a t lm i n t e r v a l s t o i n c r e a s e t h e c o n t a c t a r e a w i t h t h e s o i l . The probe can have l e n g t h s o f up t o 20m, b u t f o r t h i s p r o j e c t a 12m l o n g probe was u s e d . The c h a r a c t e r i s t i c s o f t h e ICE ( I n t e r n a t i o n a l C o n s t r u c t i o n Equipment) 812 h y d r a u l i c v i b r a t o r (ICE 812) w i t h v a r i a b l e f r e q u e n c y a r e g i v e n i n T a b l e 1. The v i b r a t o r f r e q u e n c y i s p r o p o r t i o n a l t o the eng ine speed as i n d i c a t e d i n T a b l e 2. The probe i s moved from one l o c a t i o n t o a n o t h e r by a c r a n e o r a p i l i n g r i g . A 60 t o n c r a n e was used t o h a n d l e t h e probe f o r t h i s p r o j e c t . 36 V i b r a t o r Geophone P r o b e E SECTION AA I \lm • i F i g u r e 9 T r i S t a r Probe P r i n c i p a l , M a s s a r s c h and Vanneste (1988) 37 Total mass of vibrator, Including clamp 6670 kg Dynamic mass, including clamp 4500 kg Centrifugal force <1.13 MN Frequency <26.6 Hz Excentric moment 46.1 kg.m Maximum traction force 0.36 MN Maximum amplitude (without probe) 20 mm Note: maximum amplitude - e x c e n t r i c moment x 2 dynamic mas s T a b l e 1 C h a r a c t e r i s t i c s o f t h e ICE 812 V i b r a t o r Engine Vibrator vibrator speed speed frequency (RPM) (RPM) (Hz) 2300 1600 26.6 2010 1400 23.2 1730 1200 20.0 1440 1000 16.6 1150 800 13.3 850 600 10.0 575 400 6.6 T a b l e 2 C o n v e r s i o n From E n g i n e Speed t o V i b r a t o r F r e q u e n c y , V i b r a t o r Type ICE 812 38 8 .0 DENSIFICATION TRIALS 8 .1 Aim o f t h e D e n s i f i c a t i o n T r i a l s The optimum d e n s i f i c a t i o n p r o c e d u r e , such as o p t i m a l v i b r a t o r f r e q u e n c y , v i b r a t i o n t ime and g r i d s p a c i n g were d e t e r m i n e d i n a t r i a l a r e a . The i n f l u e n c e o f each c o m p a c t i o n parameter was examined u s i n g s e v e r a l t y p e s o f measurements . These were ground v i b r a t i o n s , s u r f a c e s e t t l e m e n t s , p o r e water p r e s s u r e , cone and s t a n d a r d p e n e t r a t i o n r e s i s t a n c e . The c o n t r a c t r e q u i r e d a t e s t a r e a t o be d e n s i f i e d by the c o m p a c t i o n p r o c e d u r e t o be used f o r t h e p r o d u c t i o n phase (acceptance t e s t ) . The l a y e r t h a t r e q u i r e d t r e a t m e n t was t h e medium dense sand l a y e r between 5.0m and 11.5m. T e s t r e s u l t s had t o be approved by t h e g e o t e c h n i c a l c o n s u l t a n t s b e f o r e a c t u a l d e n s i f i c a t i o n work c o u l d s t a r t . T h e r e f o r e , i t was d e s i r a b l e t o c a r r y out t h e p r e l i m i n a r y t r i a l s w e l l b e f o r e t h e a c c e p t a n c e t e s t s . Both t h e r e s u l t s o f t h e p r e l i m i n a r y t r i a l s and t h o s e o f t h e a c c e p t a n c e t e s t a r e d e s c r i b e d i n t h i s c h a p t e r . 8.2 M e a s u r i n g Equipment The ground v i b r a t i o n s g e n e r a t e d by t h e T r i S t a r probe were measured u s i n g one - and t h r e e - d i r e c t i o n a l geophones, p l a c e d on t h e ground s u r f a c e a t v a r y i n g d i s t a n c e s from the p r o b e . W i t h t h e t h r e e - d i r e c t i o n a l geophone, h o r i z o n t a l as w e l l as v e r t i c a l v i b r a t i o n s c o u l d be measured s i m u l t a n e o u s l y . The A C - v o l t a g e g e n e r a t e d due t o the v i b r a t i o n s was t r a n s f o r m e d i n t o a r o o t mean square (RMS) v e l o c i t y . The RMS - v i b r a t i o n l e v e l i s measured as i t can be r e l a t e d t o the o b t a i n e d d e n s i f i c a t i o n i . e . the h i g h e r t h e RMS - v i b r a t i o n l e v e l , t h e h i g h e r t h e c o m p a c t i o n . Hence t h e optimum v i b r a t i o n f r e q u e n c y , g r i d s p a c i n g and v i b r a t i o n t i m e can be d e t e r m i n e d . S u r f a c e s e t t l e m e n t s were measured u s i n g c o n v e n t i o n a l l e v e l l i n g t e c h n i q u e , c a r r i e d out b e f o r e and a f t e r c o m p l e t i o n o f d e n s i f i c a t i o n . E x c e s s p o r e water p r e s s u r e s (p .w.p) were measured by an open s t a n d p i p e , i n s t a l l e d n e a r C P T U ' s 6 and 7. A p l a s t i c p i p e was p l a c e d i n a p r e - b o r e d , 5.8m (19 f e e t ) deep h o l e . The porous t i p c o n s i s t e d o f a f i l t e r w i t h a 2.4m (8 f ee t ) s l o t t e d s c r e e n a t t h e bottom end . Pore water p r e s s u r e measurements were made d u r i n g some t r i a l s b e f o r e , d u r i n g and a f t e r d e n s i f i c a t i o n . T h i s d a t a i s o n l y q u a l i t a t i v e due t o t h e l a g e f f e c t o c c u r r i n g between the probe h o l e and the s t a n d p i p e . From a p r a c t i c a l p o i n t o f v i e w , t h e most i m p o r t a n t v e r i f i c a t i o n method was by means o f p e n e t r a t i o n t e s t s . A l t h o u g h C P T U ' s y i e l d more d e t a i l e d g e o t e c h n i c a l i n f o r m a t i o n , t h e g e o t e c h n i c a l c o n s u l t a n t s p e c i f i e d S P T ' s as he had e x t e n s i v e l o c a l e x p e r i e n c e w i t h t h i s method. C o n s e q u e n t l y , b o t h t y p e s o f p e n e t r a t i o n t e s t s were p e r f o r m e d . E x t e n s i v e C P T U ' s made i t p o s s i b l e t o document i n d e t a i l t h e a c h i e v e d d e n s i f i c a t i o n . T h e r e a f t e r , a 40 l i m i t e d number o f S P T ' s were per formed i n o r d e r t o f o r m a l l y check t h e o b t a i n e d d e n s i f i c a t i o n . 8.3 T r i a l S i t e s Two t r i a l s i t e s were chosen t o d e t e r m i n e t h e o p t i m a l compact ion p r o c e d u r e . The v a l u e s f o r t h e v a r i o u s compact ion parameters a r e shown i n T a b l e 3 . T r i a l A r e a I I I T a b l e 3 -G r i d S p a c i n g (m) 2.3 1.75 S teady S t a t e Frequency (Hz) 20 13 V i b r a t i o n Time (min. ) 12 14 T r i S t a r V a r i a b l e s F o r T r i a l A r e a I and I I 8 . 3 . 1 V i b r a t i o n Time and Frequency The v i b r a t i o n t i m e and f r e q u e n c y were v a r i e d and a n a l y z e d u n t i l the maximum ground v i b r a t i o n was a c h i e v e d . 8 . 3 . 2 Pore Water P r e s s u r e The p . w . p . measurements f o r each s i t e showed t h e same b e h a v i o u r . A t f i r s t , a s m a l l p o s i t i v e exces s p . w . p . was n o t e d , f o l l o w e d by a l a r g e n e g a t i v e exces s p . w . p . which q u i c k l y d i s s i p a t e d . The p o s i t i v e p . w . p . was due t o the s o i l l i q u e f y i n g t h e n as i t q u i c k l y d r a i n e d t h e l a r g e n e g a t i v e p . w . p . o c c u r r e d . 41 8 . 3 . 3 Ground S u r f a c e S e t t l e m e n t I t was found t h a t t h e major s e t t l e m e n t o c c u r r e d i m m e d i a t e l y a f t e r d e n s i f i c a t i o n a f t e r which o n l y a s l i g h t i n c r e a s e w i t h t ime was n o t e d . F u r t h e r , t h e maximum s e t t l e m e n t c o i n c i d e d w i t h an optimum t i m e o f v i b r a t i o n . T a b l e 4 g i v e s t h e s e t t l e m e n t v a l u e s . The g r i d c o n f i g u r a t i o n was t r i a n g u l a r and t h e c e n t r e o f g r i d r e f e r s t o t h e c e n t r e o f t h e t r i a n g l e . 8 . 3 . 4 CPTU R e s u l t s P e n e t r a t i o n t e s t s executed s h o r t l y a f t e r c o m p l e t i o n o f t h e d e n s i f i c a t i o n a t T r i a l A r e a I , i n d i c a t e a s m a l l d e c r e a s e o f the cone r e s i s t a n c e ( F i g u r e 1 0 ) . However, a l a r g e i n c r e a s e o f the cone r e s i s t a n c e was o b s e r v e d w i t h e l a p s e d t i m e a t T r i a l A r e a I I , as shown i n F i g u r e 11. These l a t t e r cone r e s i s t a n c e p r o f i l e s s a t i s f i e d t h e minimum c o m p a c t i o n c r i t e r i a . F i g u r e 12 shows t h a t t h e cone b e a r i n g p r o f i l e i s t h e same f o r t h e g r i d p o i n t and t h e T r i S t a r p r o b e p o i n t . Hence, t h e maximum compact ion i s b e i n g a c h i e v e d a c r o s s t h e whole w i d t h o f t r e a t m e n t . 8 . 3 . 5 SPT R e s u l t s The S P T ' s were o n l y c a r r i e d out i n T r i a l A r e a I I so no c o m p a r i s o n can be made between t h e two a r e a s . However, as can be seen from T a b l e 5, t h e r e q u i r e d c o m p a c t i o n v a l u e s were l a r g e l y exceeded f o r T r i a l A r e a I I . 42 Type of point Average s e t t l e -ment immediately after d e n s i f i -ca t ion (m) Average s e t t l e ments 60 hours after d e n s i f i -cation (m) Denslfication point 0.31 0.32 Center point of grid 0 .22 0.25 Point 1.75 m away from de n s i f i c a t i o n point 0.10 0.12 Point 3.50 m away from de n s i f i c a t i o n point 0.05 0.07 T a b l e 4 Average Ground S u r f a c e S e t t l e m e n t s F i g u r e 10 - Cone R e s i s t a n c e P r o f i l e s B e f o r e and A f t e r D e n s i f i c a t i o n : C P T U ' s 7 and 10; F r a n k i T r i a l A r e a I F i g u r e 11 - Cone R e s i s t a n c e P r o f i l e s B e f o r e and A f t e r D e n s i f i c a t i o n : C P T U ' s 8, 12, and 13; F r a n k i T r i a l A r e a I I 45 E x '0 fc ui o IS 20 CONE RESISTANCE(MPo) • . . «P . . . 2P **** _ Ctnttr point (CPT18) (grid spacing • 175m) . . Tri star point (CPT20) F i g u r e 12 - Cone R e s i s t a n c e P r o f i l e s A f t e r D e n s i f i c a t i o n a t G r i d C e n t r e P o i n t (CPTU 18) and a t D e n s i f i c a t i o n P o i n t (CPTU 2 0 ) : F r a n k i T r i a l A r e a 46 Depth (») Req ulred minimum blowcount Obtained blowcounc DH 101 DH 102 DH 103 1.5 — 31 25 34 3.1 - 7 8 9 4.6 14 18 16 6 6.1 16 23 23 25 7.6 16 42 39 29 9.1 17 53 65 40 10.7 — 27 18 T a b l e 5 S t a n d a r d P e n e t r a t i o n T r i a l R e s u l t s f o r T r i a l A r e a I I 47 8.4 P r o d u c t i o n Phase 8 . 4 . 1 E x e c u t i o n Parameters A f t e r an e x a m i n a t i o n o f a l l t e s t r e s u l t s from t h e f i n a l t r i a l a r e a , t h e g e o t e c h n i c a l c o n s u l t a n t a c c e p t e d the T r i S t a r compact ion method. The same d e n s i f i c a t i o n parameters as i n T r i a l A r e a I I were chosen t o d e n s i f y t h e complete s t r i p a r e a . However, i t was d e c i d e d t o i n c r e a s e the compact ion depth t o 11m f o r the wes tern h a l f o f the s t r i p a r e a , and t o 10m depth f o r the e a s t e r n h a l f . The s e l e c t e d d e n s i f i c a t i o n parameters a r e shown i n F i g u r e s 13 and 14 and a r e summarized i n T a b l e 6. The comple te s t r i p a r e a was d i v i d e d i n t o 100 f e e t l o n g s e c t i o n s . Each s e c t i o n was d e n s i f i e d i n 3 passes as i l l u s t r a t e d i n F i g u r e 13. In t h i s manner, the e l a p s e d t ime between the d e n s i f i c a t i o n o f 2 a d j a c e n t p o i n t s c o u l d be i n c r e a s e d . 8 . 4 . 2 D e n s i f i c a t i o n R e s u l t s 8 . 4 . 2 . 1 S e t t l e m e n t Measurements Ground s u r f a c e s e t t l e m e n t s were measured immedia te ly a f t e r d e n s i f i c a t i o n a t a l l d e n s i f i c a t i o n p o i n t s and a t a l l g r i d "centre" p o i n t s l o c a t e d a t the c e n t r e l i n e f o r the zone w i t h 2 rows o f d e n s i f i c a t i o n p o i n t s . I n the zone w i t h 3 rows o f d e n s i f i c a t i o n p o i n t s , measurements were per formed between two d e n s i f i c a t i o n p o i n t s , l o c a t e d a t t h e c e n t r e row o f d e n s i f i c a t i o n p o i n t s . The above l o c a t i o n s can be 48 1 DISTANCE S TO DYKE ( f t ) k uJcr, 55 Ai X> A? A - 5Z5 a) A 2 A i A 3 - *7.5 IS U J Q CD UJj_ O UJ < to' rr ml. A3 A 2 A!--A 2 A ' A 1  50 .47.5 40 b) F i g u r e 13 - P a t t e r n o f D e n s i f i c a t i o n P o i n t s D u r i n g t h e P r o d u c t i o n S t a g e , G r i d S p a c i n g o f 6 f e e t : a) 15 f e e t Wide Zone b) 10 f e e t Wide Zone, M a s s a r s c h and Vannes te (1988) 49 TIME(min) 0 2 4 6 8 10 12 U 16 FREQUENCY(Hz) TIMEJmin) b) FREQUENCY(Hr) F i g u r e 14 - D e s i r e d Working Scheme D u r i n g the P r o d u c t i o n S tage : Probe Depth and V i b r a t o r Frequency as a F u n c t i o n o f T i m e ; a) West H a l f o f S t r i p A r e a b) E a s t H a l f o f S t r i p A r e a , M a s s a r s c h and Vannes te (1988) 50 Part of s t r i p area Western half Eastern half grid: pattern spacing (m) triangular 2 triangular 2 penetration: depth (m) time (min.s) frequency (Hz) 11 2 .30 20 10 2 .30 20 steady state: time (min.s) frequency (Hz) 3 13 A 13 extraction: step surging levels (m) 9 and 6 8 and 6 Total vibration time (min) 15 13 T a b l e 6 Compact ion P r o c e d u r e D u r i n g t h e P r o d u c t i o n Phase 51 l o c a t e d u s i n g F i g u r e 13. The r e s u l t s o f t h e s e measurements a r e summarized i n T a b l e 7. A s i g n i f i c a n t i n c r e a s e was o b s e r v e d o f t h e s e t t l e m e n t s i n t h e compacted s t r i p a r e a , compared t o T r i a l A r e a I I , see T a b l e 4. A l t h o u g h no i m p o r t a n t d i f f e r e n c e between the s o i l c o n d i t i o n s i n t h e e a s t e r n and w e s t e r n h a l v e s c o u l d be d i s t i n g u i s h e d , i t seems t h a t t h e l e a s t d e n s i f i e d zone was l o c a t e d between s t a t i o n s - 50 and 0, i . e . the wes tern end. 8 . 4 . 2 . 2 SPT and CPTU R e s u l t s The a c h i e v e d d e n s i f i c a t i o n was checked i n some l o c a t i o n s by means o f s t a n d a r d p e n e t r a t i o n t e s t s (SPT) u s i n g t h e "Donut" hammer. A d d i t i o n a l p e n e t r a t i o n t e s t s (CPT) were a l s o p e r f o r m e d , u s i n g t h e p i e z o c o n e (CPTU), and a l l were l o c a t e d a t probe h o l e s except f o r l a t e r a l t e s t i n g . The r e s u l t s o f t h e S P T ' s a r e g i v e n i n T a b l e 8. These t e s t r e s u l t s agree w e l l w i t h t h o s e o b t a i n e d i n T r i a l A r e a I I and i n d i c a t e t h a t t h e r e q u i r e d d e n s i f i c a t i o n i n t h e sand zone from 5.0m - 10.0m was exceeded . Low b lowcounts o r cone r e s i s t a n c e v a l u e s were measured i n the s i l t l a y e r s f o r which t h e s p e c i f i e d d e n s i f i c a t i o n was not a p p l i c a b l e . Some o t h e r i n t e r e s t i n g compar i sons a r e shown i n F i g u r e s 15, 16, and 17. Cone r e s i s t a n c e p r o f i l e s o f nearby CPTU's b e f o r e and a f t e r d e n s i f i c a t i o n a r e compared i n F i g u r e 15. CPTU 3 was c a r r i e d out b e f o r e d e n s i f i c a t i o n and was l o c a t e d o n l y 1.2m away from CPTU 24, which i t s e l f was executed 7 52 Zone between stations Average s e t t l e - Average s e t t l e -ment at corapac- ment at "center" tion point point (m) (m) - 50 to 0 coinciding with f i n a l d e n s i f i c a t i o n 0.20 0.15 test area adjacent to f i n a l 0.34 0.31 dens i f i c a t i o n test area 0 to 100 coinciding with f i n a l d e n s i f i c a t i o n 0.19 0.18 test area adjacent to f i n a l 0.45 0.38 densifi c a t i o n test area 100 to 200 0 .40 0.37 200 to 300 0 .44 0.42 300 to 400 0.44 0.39 400 to 500 0.49 0.45 500 to 600 0.48 0.40 600 to 7 00 0.43 0.41 T a b l e 7 Average Ground S u r f a c e S e t t l e m e n t s f o r P r o d u c t i o n Stage Immediate ly A f t e r D e n s i f i c a t i o n 53 Depth Required After Compaction Be fo re minimum Compac tion (o) blowcount DH 104 DH 105 DH 106 DH 107 DH 2 1.5 14 20 26 17 14 3.1 3* 5* 27 26 5* 4.6 14 4* 20 10* 21 5* 6.1 16 41 49 66 5* 8* 7.6 16 55 64 70 43 16 9.1 17 67 47 62 81 14 10.7 22 23 78 72 13 * i n s i l t l a y e r T a b l e 8 S t a n d a r d P e n e t r a t i o n Blowcounts f o r P r o d u c t i o n S tage 6 Days A f t e r D e n s i f i c a t i o n 54 F i g u r e 15 - Cone R e s i s t a n c e P r o f i l e s B e f o r e and A f t e r D e n s i f i c a t i o n : C P T ' s 3 and 24; P r o d u c t i o n S tage , M a s s a r s c h and V a n n e s t e (1988) 55 CPT26 = SPT107 Cat KAJIIMS FRICTION RATIO X B L O W C O U N T F i g u r e 16 - C o r r e s p o n d i n g CPT and SPT R e s u l t s A f t e r D e n s i f i c a t i o n : P r o d u c t i o n S t a g e , M a s s a r s c h and Vannes te (1988) 56 CONE RESISTANCE (MPa) Smttrw away(CPT21) _ _ 2m«tr« away(CPT22) trrwtre away (CPT23) Tri Star point (CPT24) F i g u r e 17 - Cone R e s i s t a n c e P r o f i l e s 6 Days A f t e r D e n s i f i c a t i o n 0, 1, 2, and 3m From t h e D e n s i f i c a t i o n P o i n t : P r o d u c t i o n S t a g e , M a s s a r s c h and Vannes te (1988) days a f t e r d e n s i f i c a t i o n and was l o c a t e d n e a r a d e n s i f i c a t i o n p o i n t . The seven day i n t e r v a l was chosen by t h e c o n t r a c t o r as i t was f e l t t h a t t h e most s i g n i f i c a n t e f f e c t o f d e n s i f i c a t i o n would have o c c u r r e d by t h i s t i m e . T h i s compar i son sugges t s t h a t a s i g n i f i c a n t d e n s i f i c a t i o n was o b t a i n e d w i t h i n t h e sand l a y e r from 5.0 t o 10m d e p t h . No change has o c c u r r e d below t h e probe p e n e t r a t i o n depth o f 10m. These r e s u l t s were a l s o observed i n T r i a l A r e a I I . The r a t i o o f t h e cone r e s i s t a n c e ( q c ) t o t h e b lowcount (N) was checked a t CPTU 26, l o c a t e d n e a r SPT 107. The r e s u l t s o f b o t h t e s t s a r e compared i n F i g u r e 15 and suggest t h a t t h e q _ / N r a t i o was a p p r o x i m a t e l y 2 .5 (q_ i n b a r ) . T h i s agrees w i t h the f i n d i n g s a t T r i a l A r e a I I , f o r which t h e q „ / N r a t i o c o r r e s p o n d e d t o 2 . 5 . Some C P T U ' s were c a r r i e d out a t i n c r e a s i n g d i s t a n c e from t h e same d e n s i f i c a t i o n p o i n t i n o r d e r t o i n v e s t i g a t e the i n f l u e n c e o f d i s t a n c e on t h e a c h i e v e d d e n s i f i c a t i o n . R e s u l t s o f t h e s e t e s t s a r e g i v e n i n F i g u r e 17 and show t h a t t h e o b t a i n e d d e n s i f i c a t i o n was by f a r t h e l a r g e s t a t the d e n s i f i c a t i o n p o i n t i t s e l f , w h i l e a s m a l l i n c r e a s e o c c u r s a t lm , b u t no t 2 o r 3m from t h e d e n s i f i c a t i o n p o i n t . Note t h a t C P T U ' s 21 , 22, and 23 were a l l l o c a t e d o u t s i d e o f t h e a r e a t o be compacted. F o r f u r t h e r i n f o r m a t i o n r e g a r d i n g the t r i a l s , a d e t a i l e d d e s c r i p t i o n i s g i v e n by M a s s a r s c h and V a n n e s t e , 1988. 58 9 .0 U . B . C . TESTING PROGRAM 9 .1 I n t r o d u c t i o n I n - s i t u t e s t s were per formed t o i n v e s t i g a t e the g e o t e c h n i c a l c o n d i t i o n s a t the s i t e and t o m o n i t o r the per formance o f t h e T r i - S t a r p r o b e . T h i s s e c t i o n d e s c r i b e s t h e p r o c e d u r e s and t e c h n i q u e s used i n c a r r y i n g out the v a r i o u s i n - s i t u t e s t s . The CPT and DMT t e s t s were per formed i n a c c o r d a n c e w i t h t h e p r o c e d u r e s l a i d down by t h e A m e r i c a n S o c i e t y f o r T e s t i n g and M a t e r i a l s , namely, ASTM D3441-86 f o r t h e CPT and ASTM D 18 .02 .10 -86 f o r t h e DMT. O t h e r i n - s i t u t e s t s l i k e s e i s m i c cone and l a t e r a l s t r e s s cone have no d e s i g n a t e d s t a n d a r d s , t h u s the p r o c e d u r e f o l l o w e d u s u a l U . B . C . p r a c t i c e , which has e v o l v e d t h r o u g h wide g e o t e c h n i c a l f i e l d t e s t i n g e x p e r i e n c e . 9.2 I n - S i t u T e s t s 9 . 2 . 1 T e s t i n g V e h i c l e A l l i n - s i t u t e s t s were per formed from t h e U . B . C . G e o t e c h n i c a l R e s e a r c h V e h i c l e . T h i s v e h i c l e i s d e s i g n e d t o p e r f o r m a v a r i e t y o f i n - s i t u t e s t s i n a s e l f - c o n t a i n e d l a b o r a t o r y env ironment . These i n c l u d e t h e m e c h a n i c a l cone , f l a t d i l a t o m e t e r , screw p l a t e , s e l f b o r i n g and f u l l d i s p l a c e m e n t p i e z o m e t e r s , t o g e t h e r w i t h t h e a b i l i t y t o r e t r i e v e p i s t o n samples . The d e s i g n i s such t h a t w i t h t h e e x c e p t i o n o f l e v e l l i n g t h e t r u c k and i n i t i a t i n g a p e n e t r a t i o n , v i r t u a l l y a l l o f t h e t e s t i n g p r o c e d u r e s can be c a r r i e d out from i n s i d e . 59 Once i t i s on s i t e and p o s i t i o n e d f o r a s o u n d i n g , i t i s e l e v a t e d w i t h two h y d r a u l i c pads t o p r o v i d e a l e v e l and s t a b l e w o r k i n g p l a t f o r m . A more d e t a i l e d d e s c r i p t i o n o f the v e h i c l e i s g i v e n by Campane l la and R o b e r t s o n (1981) . 9 . 2 . 2 T e s t s Performed A c c o r d i n g t o Campane l la and R o b e r t s o n (1981) , i n - s i t u t e s t s may be b r o a d l y d i v i d e d i n t o two c a t e g o r i e s : 1. l o g g i n g methods 2. s p e c i f i c methods L o g g i n g methods a r e g e n e r a l l y economic and q u i c k t o p e r f o r m , and a r e used p r i m a r i l y f o r s t r a t i g r a p h i c p r o f i l i n g . They can a l s o y i e l d q u a l i t a t i v e c o r r e l a t i o n s t o o b t a i n g e o t e c h n i c a l d e s i g n parameters (Rober t son and C a m p a n e l l a , 1986) . S p e c i f i c t e s t methods a r e o f t e n s lower and more c o s t l y t h a n l o g g i n g methods, and a r e used p r i m a r i l y f o r t h e measurement o f s o i l p r o p e r t i e s a t a p o i n t . The l o g g i n g methods a r e t h e r e f o r e b e s t s u i t e d t o t h e p r e l i m i n a r y e v a l u a t i o n o f s o i l p a r a m e t e r s . The cone p e n e t r a t i o n t e s t i s t h e most r a p i d o f the l o g g i n g t y p e i n - s i t u t e s t s and the a d d i t i o n o f t h e pore p r e s s u r e measur ing element has improved the e v a l u a t i o n o f s o i l p a r a m e t e r s . C o n s e q u e n t l y , t h e e l e c t r o n i c p i e z o c o n e was s e l e c t e d as t h e p r i m a r y t o o l f o r e v a l u a t i o n o f t h e T r i S t a r p r o b e . 60 The f l a t d i l a t o m e t e r was used s e l e c t i v e l y , t o i d e n t i f y changes i n h o r i z o n t a l s t r e s s and a s s e s s changes i n s o i l modulus and a l s o t o c o n f i r m the CPT r e s u l t s . T e s t s were a l s o per formed w i t h t h e s e i s m i c p i e z o c o n e t o p r o v i d e i n f o r m a t i o n on t h e dynamic shear modulus b e f o r e and a f t e r t r e a t m e n t . F i n a l l y a l a t e r a l s t r e s s e l e c t r o n i c p i e z o c o n e was used t o e v a l u a t e t h e changes i n the h o r i z o n t a l s t r e s s b e f o r e and a f t e r t r e a t m e n t . Each o f t h e above i n s t r u m e n t s and t h e i r p r o c e d u r e i s d e s c r i b e d be low. 9 . 2 . 2 . 1 P i e z o c o n e P e n e t r a t i o n T e s t (CPTU) P i e z o c o n e T e s t s were per formed u s i n g a cone w i t h a 10cm base a r e a and an Apex a n g l e o f 6 0 ° , i n a c c o r d a n c e w i t h ASTM S t a n d a r d D3441, 1986. The f r i c t i o n s l e e v e , l o c a t e d above 2 t h e c o n i c a l t i p , has a s t a n d a r d a r e a o f 150cm and i s the same d i a m e t e r as t h e c o n i c a l t i p and push r o d s , i . e . 35.7mm. Pore p r e s s u r e s a r e measured s i m u l t a n e o u s l y b e h i n d the t i p o r on t h e f a c e and b e h i n d t h e f r i c t i o n s l e e v e . Measurements o f p o r e water p r e s s u r e , cone b e a r i n g , s l e e v e f r i c t i o n , i n c l i n a t i o n and t e m p e r a t u r e a r e t y p i c a l l y r e c o r d e d e v e r y 50mm o r as s p e c i f i e d , 25mm a t U . B . C . D e t a i l s o f t h e v a r i o u s p i e z o c o n e d e s i g n s a r e g i v e n by Campane l la and R o b e r t s o n (1988) . 61 Depending on t h e cone d e s i g n , cone measurements can be s u s c e p t i b l e t o t emperature v a r i a t i o n , t h e r e f o r e c o r r e c t i o n s may be n e c e s s a r y , R o b e r t s o n and Campane l la (1986) . B e f o r e g o i n g out i n t o t h e f i e l d each cone i s checked f o r o p e r a t i o n , c a l i b r a t i o n and t h e n c a r e f u l l y s a t u r a t e d . Porous p o l y p r o p y l e n e f i l t e r e l ement s , 5mm w i d e , are s a t u r a t e d w i t h g l y c e r i n e under a vacuum. The i n s t r u m e n t t h e n has t o be c a r e f u l l y assembled under g l y c e r i n e t o e l i m i n a t e a i r from the p o r e p r e s s u r e measurement sys tem. T h e r e a f t e r , i t i s kep t under g l y c e r i n e u n t i l r e q u i r e d . F u l l d e t a i l s o f t h e s a t u r a t i o n p r o c e d u r e as c a r r i e d out a t U . B . C . i s d e s c r i b e d by R o b e r t s o n and Campane l la (1986) . To c o n f i r m i n s t r u m e n t c a l i b r a t i o n , b a s e l i n e s a r e r e c o r d e d b e f o r e and a f t e r e v e r y s o u n d i n g . In t h e f i e l d , cone d a t a i s r e c o r d e d a u t o m a t i c a l l y u s i n g t h e H o g e n t o g l e r and C o . d a t a a c q u i s i t i o n system i n t h e U . B . C . G e o t e c h n i c a l R e s e a r c h V e h i c l e . T h i s system c o n s i s t s o f a R a d i o Shack TRS 80 LED d i s p l a y p o r t a b l e computer , a s t a n d a r d buss i n t e r f a c e , Z80 CPU, 12 b i t A / D , a l i n e p r i n t e r , and a b u b b l e memory s t o r a g e d e v i c e . Once back a t t h e l a b o r a t o r y t h e d a t a i s downloaded from t h e b u b b l e d e v i c e t o a p e r s o n a l computer f o r p r o c e s s i n g . 9 . 2 . 2 . 2 F l a t D i l a t o m e t e r P e n e t r a t i o n T e s t (DMT) The F l a t D i l a t o m e t e r t e s t (DMT) was f i r s t i n t r o d u c e d i n t o N o r t h A m e r i c a i n 1980 ( M a r c h e t t i , 1980) and has become a s i m p l e i n - s i t u t e s t . The d i l a t o m e t e r i s a f l a t b l a d e 62 15mm t h i c k , 95mm wide by 220mm i n l e n g t h . A f l e x i b l e s t a i n l e s s s t e e l membrane 60mm i n d i a m e t e r i s l o c a t e d on one f a c e o f t h e b l a d e . The membrane i s u s u a l l y i n f l a t e d u s i n g h i g h p r e s s u r e n i t r o g e n gas s u p p l i e d by a tube p r e - t h r e a d e d t h r o u g h t h e push r o d s . Beneath t h e membrane i s a s e n s i n g d e v i c e which t u r n s a b u z z e r o f f i n the c o n t r o l box when the membrane s t a r t s t o l i f t o f f and t u r n s a b u z z e r on a g a i n a f t e r a d e f l e c t i o n o f 1.1mm a t t h e c e n t r e o f t h e membrane. As t h e membrane i s i n f l a t e d , t h e p r e s s u r e r e q u i r e d t o j u s t l i f t t h e membrane o f f t h e s e n s i n g d e v i c e ( r e a d i n g A ) , and t o cause 1.1mm d e f l e c t i o n ( r e a d i n g B) a r e r e c o r d e d . As the p r e s s u r e i s r e l e a s e d and the membrane r e t u r n s t o i t s i n i t i a l l i f t o f f p o s i t i o n t h e r e a d i n g C can be r e c o r d e d . T h i s p r o v i d e s a measure o f t h e i n i t i a l i n - s i t u water p r e s s u r e TJQ i n sand s o i l s when t h e m a t e r i a l i n d e x ( I D ) i s e q u a l o r g r e a t e r t h a n a p p r o x i m a t e l y 2. I n c l a y s ( I D < 0.8) t h e C r e a d i n g i s c l o s e t o t h e p o r e p r e s s u r e g e n e r a t e d d u r i n g p e n e t r a t i o n . Readings a r e g e n e r a l l y made e v e r y 200mm i n d e p t h . The t h r u s t i s measured a t t h e s u r f a c e w i t h a l o a d c e l l and i s used t o e s t i m a t e t h e f r i c t i o n a n g l e o f t h e s o i l . These r e a d i n g s a r e made from a p r e s s u r e gauge i n t h e c o n t r o l box a t t h e s u r f a c e and e n t e r e d on a s t a n d a r d d a t a f o r m . F u l l d e t a i l s o f t h e s t a n d a r d t e s t p r o c e d u r e s a r e g i v e n i n sugges ted ASTM Method f o r P e r f o r m i n g t h e F l a t D i l a t o m e t e r T e s t (ASTM Sub-Committee D 1 8 . 0 2 . 1 0 , 1986) . 63 The A and B r e a d i n g s a r e c o r r e c t e d f o r membrane s t i f f n e s s and no ted as P Q and P 1 r e s p e c t i v e l y . The c o r r e c t e d membrane l i f t o f f and 1.1mm d i s p l a c e m e n t p r e s s u r e s can be used t o d e f i n e t h r e e i n d e x p a r a m e t e r s . These a r e d e s c r i b e d by M a r c h e t t i (1980) as t h e m a t e r i a l i n d e x ( I D ) , t h e h o r i z o n t a l s t r e s s i n d e x (K D ) and the d i l a t o m e t e r modulus ( E D ) . From t h e s e i n d i c e s , e m p i r i c a l r e l a t i o n s h i p s have been d e v e l o p e d t o d e t e r m i n e g e o t e c h n i c a l p a r a m e t e r s . D e t a i l s o f t h e o r i g i n a l c o r r e l a t i o n s may be found i n M a r c h e t t i (1980), w i t h l a t e r developments by Schmertmann (1983) . 9 . 2 . 2 . 3 S e i s m i c P i e z o c o n e P e n e t r a t i o n T e s t (SCPTU) The i n c o r p o r a t i o n o f a s m a l l rugged v e l o c i t y se ismometer i n t o a p i e z o c o n e has made i t p o s s i b l e t o r o u t i n e l y measure t h e s m a l l s t r a i n s h e a r wave v e l o c i t y , d u r i n g a p i e z o c o n e s o u n d i n g (Campanel la and R o b e r t s o n 1986) . The cone p e n e t r o m e t e r c o n t a i n i n g t h e se ismometer i s pushed t o the f i r s t t e s t d e p t h . The se ismometer i s o r i e n t e d i n t h e h o r i z o n t a l d i r e c t i o n and p a r a l l e l t o t h e s i g n a l s o u r c e t o d e t e c t t h e h o r i z o n t a l component o f s h e a r waves. Shear waves a r e g e n e r a t e d a t the ground s u r f a c e by s t r i k i n g the t r u c k pads h o r i z o n t a l l y w i t h a s l e d g e hammer, b o t h s i d e s o f t h e t r u c k b e i n g s t r u c k i n t u r n . A t any t e s t d e p t h , two waveforms a r e o b t a i n e d , r e p r e s e n t i n g o p p o s i t e p o l a r i s e d waves. A h i g h q u a l i t y o s c i l l o s c o p e i s n e c e s s a r y t o r e c o r d and v iew t h e waveforms. The t ime r e q u i r e d f o r the shear 6 4 wave to reach the seismometer i n the cone i s recorded. This procedure i s repeated at lm i n t e r v a l s . The t r a v e l time i s v e c t o r i a l l y corrected to the equivalent v e r t i c a l t r a v e l path time and the i n t e r v a l time calculated. The shear waves t r a v e l through the s o i l skeleton and are thus r e l a t e d to the s o i l shear modulus. E l a s t i c theory re l a t e s the shear modulus, G, s o i l density y O and the shear wave v e l o c i t y , V g as follows: G =/>* V s 2 Hence, the shear modulus can be determined using i n - s i t u methods f o r the determination of the shear wave v e l o c i t y . The shear modulus i s la r g e s t at low s t r a i n s and decreases with increasing shear s t r a i n (Seed and I d r i s s , 1970). The shear s t r a i n amplitude i n i n - s i t u seismic cone t e s t s i s low and of the order of 10*~4%. Thus, the very low s t r a i n l e v e l dynamic shear modulus, G^j^, i s obtained. 9.2.2.4 Lateral Stress Piezocone Penetration Test (LSCPTU) Lateral stresses are measured by means of a l a t e r a l stress module pushed into the ground behind a 15cm CPTU. The l a t e r a l stress i s monitored 0.75m behind the t i p using a second f r i c t i o n sleeve instrumented to measure hoop stresses i n a thin-walled section of the sleeve. The l a t e r a l s t r e s s cone (LSCPTU) i s capable of measuring the following parameters: 65 1. cone b e a r i n g 2. s l e e v e f r i c t i o n immedia te ly b e h i n d t h e t i p 3. p o r e p r e s s u r e a t 2 o f 3 l o c a t i o n s , i . e . on t h e f a c e o r b e h i n d t h e t i p and b e h i n d t h e f r i c t i o n s l e e v e 4. t e m p e r a t u r e I n a d d i t i o n , a t the l o c a t i o n o f the l a t e r a l s t r e s s s l e e v e t h e f o l l o w i n g a r e a l s o measured: 1. p o r e p r e s s u r e 2. s l e e v e f r i c t i o n 3 . l a t e r a l s t r e s s D e t a i l s o f t h e l a t e r a l s t r e s s cone a r e g i v e n i n Campane l la e t . a l . (1990) . The d a t a i s s t o r e d on t h e U . B . C . r e s e a r c h d a t a a c q u i s i t i o n system and l a t e r t r a n s f e r r e d t o f l o p p y d i s k . I n terms o f l a t e r a l s t r e s s measurements t h e f o l l o w i n g c o r r e c t i o n s have t o be a p p l i e d : 1. c o r r e c t i o n f o r l a t e r a l s t r e s s / f r i c t i o n c r o s s - t a l k 2. c o r r e c t i o n f o r t e m p e r a t u r e dependence o f l a t e r a l s t r e s s b a s e l i n e . The s t r e s s measurements a r e per formed i n d i s t u r b e d s o i l s i n c e t h e method o f i n s e r t i o n i s o f t h e f u l l d i s p l a c e m e n t t y p e . To de termine t h e t r u e i n - s i t u s t r e s s e s t h e e f f e c t o f s t r e s s change due t o d i s p l a c e m e n t has t o be e v a l u a t e d . However, t h e d i f f e r e n c e i n t h e measured s t r e s s e s b e f o r e and a f t e r ground t r e a t m e n t may be u s e f u l i n e v a l u a t i n g the degree o f improvement and o b v i a t e t h e need t o e v a l u a t e a c t u a l s t r e s s c o n d i t i o n s . 66 9.3 F i e l d T e s t Programme 9 . 3 . 1 O b j e c t i v e The o b j e c t i v e o f t h e f i e l d t e s t i n g was p r i m a r i l y t o i n v e s t i g a t e t h e t i m e e f f e c t o f s t r e n g t h g a i n i n c o h e s i o n l e s s s o i l s a f t e r b e i n g v i b r o c o m p a c t e d by the T r i -S t a r p r o b e . S e c o n d l y , t o i n v e s t i g a t e t h e T r i S t a r p r o b e ' s zone o f i n f l u e n c e and a l s o t o i n v e s t i g a t e how t h e l a t e r a l s t r e s s , p o r e water p r e s s u r e measured by t h e CPTU and v a r i o u s g e o t e c h n i c a l parameters were a f f e c t e d . 9 . 3 . 2 Scope o f Work I n o r d e r t o a t t a i n t h e o b j e c t i v e s t h r e e d i s t i n c t a r e a s were chosen f o r t h e i n v e s t i g a t i o n . The l o c a t i o n o f t h e s e a r e a s , and t h e v i r g i n a r e a p e n e t r a t i o n t e s t s and o t h e r r e l e v a n t f e a t u r e s a r e shown i n F i g u r e s 3 and 4. A more d e t a i l e d p l a n o f t h e T r i a l A r e a C L 500 + 00 w i t h t h e p o s i t i o n o f t h e probe h o l e s and p e n e t r a t i o n t e s t s i s shown i n F i g u r e 18. A l l a r e a s were chosen f o r t h e i r ease o f a c c e s s and i n p a r t i c u l a r , t h e T r i a l A r e a f o r compar i son t o t h e t e s t i n g done by ConeTec . The CPTU was used as t h e p r i m a r y t o o l and hence t h e o n l y i n s t r u m e n t t o i n v e s t i g a t e t h e e f f e c t o f t ime and d i s t a n c e . The r e s t compared t h e e f f e c t o f v i b r o c o m p a c t i o n b e f o r e and a f t e r . The d e t a i l s o f t h e p e n e t r a t i o n t e s t s , i . e . t y p e , t i m e c a r r i e d out and p o s i t i o n , a r e c o n t a i n e d i n T a b l e 9 and SOOtOO I* ^—i4 f f i O + + Cr - / ^ J 04Mr*-J -^*W/ ^-/rV-3 -G)—-Y\—0 O — © - r ~ * ~ T J.. +' • + + O + ct-*r+a © — © - — O C ^ i V * 4- 7* / £rv3A PROGE HOLES CEf^iT/2F^/ME OF COMPnc r/O/v F i g u r e 1 8 - D e t a i l e d P l a n o f T r i a l A r e a c L 5 0 0 + 0 0 68 T e s t Tvpe Date Comments Number (days) CPT 3 CPTU — — On C L b e f o r e CPT 5 SCPTU — On C L b e f o r e CPT 24 CPTU +6 On C L a f t e r C8-AN-1 CPTU +67 On C L a f t e r C8-AN-10 SCPTU +82 VA1 C8-AN-11 SCPTU +82 On C L a f t e r C8-AN-12 CPTU +82 lm s o u t h o f C L a f t e r C8-AN-13 CPTU +82 2m s o u t h o f C L a f t e r C8-AN-14 CPTU +82 3m s o u t h o f C L a f t e r C8-AN-18 CPTU +203 VA2 C8-AN-2 0 CPT +209 On C L a f t e r D8-AN-2 DMT + 111 On C L a f t e r , f a c i n g e a s t D8-AN-3 DMT +111 On C L a f t e r , f a c i n g n o r t h D8-AN-4 DMT +111 VA1 L S - 3 - A N LSCPTU +204 On C L a f t e r L S - 4 - A N LSCPTU +209 VA1 T a b l e 9 D e t a i l s o f P e n e t r a t i o n T e s t s s h o u l d be r e a d i n c o n j u n c t i o n w i t h F i g u r e 18. The c h o i c e o f i n t e r v a l f o r t e s t i n g was d i c t a t e d by a v a i l a b i l i t y o f equ ipment , p e r s o n n e l and a c c e s s t o t h e s i t e . 70 10.0 TEST RESULTS 10 .1 I n t r o d u c t i o n The o b j e c t o f t h i s c h a p t e r i s t o p r o v i d e a background f o r C h a p t e r 11, which d i s c u s s e s t h e i n t e r p r e t a t i o n o f t h e t e s t r e s u l t s . In an assessment o f s o i l improvement i t i s n e c e s s a r y t o a c c u r a t e l y e s t i m a t e t h e s o i l c o n d i t i o n s , o t h e r w i s e t h e degree o f improvement cannot be c o n f i d e n t l y e v a l u a t e d . As s u c h , i n - s i t u t e s t s and t h e most r e c e n t l y d e v e l o p e d i n t e r p r e t a t i o n methods have been u s e d . 10.2 CPTU Parameters The e f f e c t o f v i b r o c o m p a c t i o n on the parameters o f cone b e a r i n g , s l e e v e f r i c t i o n , and p o r e water p r e s s u r e i s d e s c r i b e d i n t h e f o l l o w i n g s e c t i o n . The d e s c r i p t i o n l o o k s a t t h e e f f e c t o f t i m e and d i s t a n c e . T h i s i s done by f i r s t showing t h e "before" p r o f i l e and t h e n t h e " a f t e r " p r o f i l e . T h e r e a f t e r each c o n s e c u t i v e p r o f i l e i n t i m e i s super imposed t o show t h e e f f e c t o f t i m e . The same i s a l s o done w i t h d i s t a n c e . W i t h r e g a r d t o any i n c r e a s e shown i n t h e f i r s t 2 -3m i t was not due t o t h e T r i S t a r p r o b e . T h i s was because t h e water t a b l e was 2 - 3m below ground l e v e l above which t h e T r i S t a r probe i s not e f f e c t i v e . The i n c r e a s e was due t o a s u r f a c e v i b r a t i n g r o l l e r which was o p e r a t i n g a c r o s s t h e whole s i t e a t v a r i o u s t imes d u r i n g t h e t e s t i n g p e r i o d . T h i s i s c o n f i r m e d by t h e f a c t t h a t no i n c r e a s e i s shown i n t h e ConeTec CPTU p r o f i l e s ( F i g u r e 15) c a r r i e d out 7 days a f t e r compact ion d u r i n g which t h e l a r g e s t i n c r e a s e i n t h e medium dense sand l a y e r o c c u r r e d . 1 0 . 2 . 1 Cone B e a r i n g 1 0 . 2 . 1 . 1 Time E f f e c t Cone b e a r i n g as a f u n c t i o n o f t ime i s shown i n F i g u r e 19. A t e s t was t a k e n b e f o r e and a t 67, 82, and 209 days a f t e r v i b r o c o m p a c t i o n . I t c a n be seen from F i g u r e 19 t h a t t h e bot tom o f t h e sand f i l l l a y e r has moved down 1.5m and remains a t t h a t new l e v e l f o r t h e p e r i o d o f t e s t i n g . T h i s i s thought t o be due t o t h e m i x i n g e f f e c t o f t h e T r i S t a r p r o b e . The p r o c e s s i n v o l v e s t h e sand f i l l d r o p p i n g down i n t o t h e s i l t y sand and m i x i n g , hence p r o d u c i n g a medium s u i t a b l e f o r v i b r o c o m p a c t i o n . T h i s i s i n t e r e s t i n g as i t shows t h a t a s i l t y s o i l may be d e n s i f i e d by a probe such as the T r i S t a r by s u p p l y i n g a s u r c h a r g e o f c o h e s i o n l e s s m a t e r i a l a t the s u r f a c e . Thus i t can be seen t h a t t h e s i l t l a y e r has been e f f e c t i v e l y reduced from 2.5m t o lm and remains as such f o r t h e p e r i o d o f t e s t i n g . The above was a l s o o b s e r v e d a t a v i b r o c o m p a c t i o n p r o j e c t i n S a u d i A r a b i a w i t h a s i m i l a r s o i l p r o f i l e ( K i r s c h and Chambosse, 1981) . T h i s i s the reason f o r d e p i c t i n g the s o i l p r o f i l e a t t h i s l o c a t i o n w i t h dashed l i n e s , so as t o i n d i c a t e t h e movement o f s o i l b o u n d a r i e s . I n t h e medium dense sand l a y e r (5m - 10m) , the a r e a s p e c i f i e d f o r t r e a t m e n t , t h e r e was c o n s i d e r a b l e change . The p l o t s o f F i g u r e 19 show an i n c r e a s e o f cone b e a r i n g w i t h DEPTH vs CONE BEARING DEPTH vs CONE BEARING 72 0. (bar) 50 100 150 200 250 300 350 J 1 1 I I l_ 50 i 100 1 Q« (bor) 150 200 250 300 350 J I I L SOIL PROFILE SANO FILL SILT UCOIUM DENSE SANO CLAYEY SILT C t 500+00 (67 DAYS after) C L 500+00 (before vcomp) C\ 500+00 (67 DAYS after) C L 500+00 (before vcomp) C L 500+00 (82 DAYS after) DEPTH vs CONE BEARING 0. (bor) 50 100 150 200 250 300 350 SOIL PROFILE SANO FILL SILT UEOIUU OCNSE SANO CLAYEY SILT C 500+00 (82 DAYS after) C L 500+00 (before vcomp) C L 500+00 (209 DAYS otter) F i g u r e 19 - E f f e c t o f Cone B e a r i n g W i t h Time 67, 82 a n d 209 Days A f t e r t ime f o r t h e 67 day and 82 day t e s t s o f 2 and 4 f o l d r e s p e c t i v e l y . However, a t 209 days t h e cone b e a r i n g drops back t o a 3 f o l d i n c r e a s e . T h i s i s s u r p r i s i n g as one would e x p e c t t h e cone b e a r i n g t o i n c r e a s e more o r t o p l a t e a u . The cause f o r t h i s may be due t o a change i n t h e ground water l e v e l due t o a d i f f e r e n t t i d e l e v e l , i . e . t h e t i d e was h i g h e r d u r i n g t h e 82 day t e s t . W i t h r e g a r d t o sand below t h e end o f t h e p r o b e , no e f f e c t i s seen a f t e r 67 days but a jump o f 50 b a r o c c u r s a f t e r 82 days and s t a y s t h e same a t 209 d a y s . Below 11.5m, t h e end o f t h e sand l a y e r no e f f e c t i s seen i n t h e c l a y e y s i l t l a y e r w i t h t i m e , which i s as e x p e c t e d . 1 0 . 2 . 1 . 2 D i s t a n c e E f f e c t The e f f e c t o f cone b e a r i n g w i t h d i s t a n c e i s shown i n F i g u r e 20. A p e n e t r a t i o n t e s t was t a k e n a t lm , 2m, and 3m from t h e c e n t r e l i n e o f v i b r o c o m p a c t i o n , as shown i n F i g u r e 18. The a s p e c t o f the sand f i l l m i x i n g w i t h t h e s i l t l a y e r can be seen i f one o b s e r v e s t h e s e r i e s o f f i g u r e s . The sand f i l l p r o f i l e g r a d u a l l y moves back from i t s peak v a l u e o f 200 b a r ( top l e f t graph) t o a lmos t i t s v i r g i n p o s i t i o n (bottom r i g h t graph) . A l s o , t h e t o p o f t h e s i l t l a y e r moves back from 4m t o 2.5m, i t s o r i g i n a l p o s i t i o n . W i t h r e g a r d t o t h e medium dense sand i t g r a d u a l l y moves back t o i t s v i r g i n s t a t e a t 3m from t h e c e n t r e l i n e . DEPTH vs CONE BEARING Q. (bor) 0 SO 100 1S0 200 250 300 350 0-U 1 I 1 I I L. DEPTH vs CONE BEARING 74 °« < b 0 r ) PROFILE 0 50 100 150 200 250 300 350 r p , u r l L t 0 - J — • — I -SANO FILL SILT UEOIUU DENSE SAND ClAYEY SILT Ct 500+00 Ct 500+00 (before vcomp) Ct 500+00 Ct 500+00 (before vcomp) 1m SOUTH OF Ct 500+00 DEPTH vs CONE BEARING DEPTH vs CONE BEARING 10-15 Q« (bor) 50 ' 100 150 200 250 300 350 ° « ( f a o r ) PROFILE 0 50 100 150 200 250 300 350 15 SANO FILL SILT MEOIUU DENSE SAND CLAYEY SILT Ct 500+00 • '• C L 500+00 (before vcomp) 2m SOUTH OF Ct 500+00 Ct 500+00 C L 500+00 (before vcomp) 3m SOUTH OF C t 500+00 Figure 20 - E f f e c t of Cone Bearing With Distance at 0,1,2,3m From The Centreline (82 days after) T h e r e f o r e , i t would appear t h a t t h e T r i - S t a r probe has a zone o f i n f l u e n c e o f about 2m r a d i u s . 1 0 . 2 . 2 S l e e v e F r i c t i o n 1 0 . 2 . 2 . 1 Time E f f e c t The e f f e c t o f s l e e v e f r i c t i o n w i t h t i m e i s shown i n F i g u r e 21. The s l e e v e f r i c t i o n e x h i b i t s t h e same b e h a v i o u r i n t h e sand f i l l and s i l t l a y e r s as d i d t h e cone b e a r i n g , i . e . the m i x i n g e f f e c t . The s l e e v e f r i c t i o n i n t h e medium dense sand i s d i f f e r e n t from t h a t o f the cone b e a r i n g . I n s t e a d o f a g r a d u a l b u i l d up w i t h t i m e , t h e r e i s an i n c r e a s e a t 67 days which remains c o n s t a n t a f t e r w a r d s . However a t i m e e f f e c t i s n o t i c e a b l e from t h e C P T U ' s done d u r i n g and a f t e r t h e t r e a t m e n t phase by t h e c o n t r a c t o r (CPT 8, 12, 13, F i g u r e 11 ) . Hence, i t c o u l d be assumed t h a t t h e s l e e v e f r i c t i o n t ime e f f e c t i s c o n s i d e r a b l y l e s s t h a n t h a t o f cone b e a r i n g . A g a i n , no e f f e c t o f v i b r o c o m p a c t i o n can be seen i n the c l a y e y s i l t l a y e r . 1 0 . 2 . 2 . 2 D i s t a n c e E f f e c t The e f f e c t o f s l e e v e f r i c t i o n w i t h d i s t a n c e i s shown i n F i g u r e 22. A g a i n , t h e a s p e c t o f t h e sand f i l l m i x i n g w i t h t h e s i l t l a y e r can be o b s e r v e d i n t h e f i r s t 4m o f t h e p r o f i l e , DEPTH vs SLEEVE FRICTION F. (bor) 0.2 0.4 0.6 0.8 J _ i 1 i I i 1.0 DEPTH vs SLEEVE FRICTION F. (bar) 1.0 76 SOIL PROFILE SANO FILL SILT MEDIUM DENSE SAND CLAYEY SILT C L 500+00 (67 DAYS after) t\ 500+00 (before vcomp) C\. 500+00 (67 DAYS after) C\ 500+00 (before vcomp) C L 500+00 (82 DAYS after) DEPTH vs SLEEVE FRICTION o.o • F. (bar) 0.2 0.4 0.6 0.8 1.0 -I 1 1 i I i ' SOIL PROFILE SANO F I X SLT MEDIUM DENSE SAND CLAYEY SILT C\ 500+00 (82 DAYS after) C t 500+00 (before vcomp) CL 500+00 (209 DAYS after) F i g u r e 21 - E f f e c t o f S l e e v e F r i c t i o n W i t h Time 67, 82, and 209 Days A f t e r DEPTH vs SLEEVE FRICTION DEPTH vs SLEEVE FRICTION F. (bor) 77 t.o SOIL PROFILE SANO FILL SILT MEDIUM DENSE SAND CLAYEY SLT C 500+00 CV 500+00 (before vcomp) Ct 500+00 Ct 500+00 (before vcomp) 1m SOUTH OF C L 500+00 DEPTH vs SLEEVE FRICTION DEPTH vs SLEEVE FRICTION F. (bor) 0.2 0.4 0.6 0.8 1.0 J 1 I I I 1 1 L. F. (bar) 0.0 0.2 0.4 0.6 n I ..L • • L SOIL PROFILE SANO FILL SILT MEDIUM DENSE SAND CLAYEY SILT C\ 500+00 C. 500+00 (before vcomp) 2m SOUTH OF C t 500+00 Ct 500+00 C L 500+00 (before vcomp) 3m SOUTH OF C L 500+00 F i g u r e 22 - E f f e c t o f S l e e v e F r i c t i o n W i t h D i s t a n c e a t 0, 1, 2, and 3m From t h e C e n t r e l i n e (82 days A f t e r ) 78 whereby t h e sand f i l l and s i l t p r o f i l e s g r a d u a l l y r e t u r n t o t h e i r v i r g i n s t a t e . As f o r t h e medium dense sand l a y e r i t e x h i b i t s t h e same b e h a v i o u r as found by t h e cone b e a r i n g , i . e . i t g r a d u a l l y r e t u r n s t o i t s v i r g i n s t a t e by 3m. T h u s , as f o r t h e c o r e b e a r i n g t h e zone o f i n f l u e n c e w i t h r e g a r d t o s l e e v e f r i c t i o n i s about 2m r a d i u s . 1 0 . 2 . 3 Pore Water P r e s s u r e Measured By CPTU U n f o r t u n a t e l y , t h e m a j o r i t y o f t h e p o r e water p r e s s u r e ( p . w . p . ) d a t a c o l l e c t e d was found t o be u n s a t i s f a c t o r y e x c e p t f o r t h e v i r g i n a r e a and t h e 209 day t e s t . T h i s was due t o equipment and o p e r a t i o n a l p r o b l e m s . W i t h r e g a r d t o t h e 209 day t e s t f o r b e h i n d t h e t i p , shown i n F i g u r e 23, t h i s shows the p . w . p . t o be h y d r o s t a t i c i n t h e t r e a t e d sand l a y e r from 5.0 - 10.0m. The same e f f e c t i s e x h i b i t e d by t h e b e h i n d t h e f r i c t i o n s l e e v e e lement and hence i s no t shown. T h i s e f f e c t was a l s o no ted i n a l l the ConeTec d a t a which showed no excess p . w . p . T h e r e f o r e , as e x p e c t e d p . w . p . i s no t e f f e c t e d i n t h e l o n g t erm a f t e r v i b r o c o m p a c t i o n i n f r e e l y d r a i n i n g s o i l . T h i s i s because t h e i n i t i a l p . w . p . i n c r e a s e i s q u i c k l y d i s s i p a t e d . DEPTH vs PORE PRESSURE U (m. of water) 0 5 10 IS 10-15-1 — C. 5 0 0 + 0 0 ( 6 7 DAYS after) VIRGIN AREA #1 Hydrostatic P.W.P. M0Td*or« prvMurv moo»ur*d BEHIND TIP DEPTH vs PORE PRESSURE U (m. of water) 0 5 10 15 J l_ 79 SOIL 2 0 PROFILE SANO na. SILT UtDIUU DENSE SANO CLAYEY SLT C. 5 0 0 + 0 0 ( 6 7 DAYS after) VIRGIN AREA #1 Q. 5 0 0 + 0 0 ( 8 2 DAYS after) H y d r o s t a t i c P.W.P. NOT&Poni prutur* m*osw«4 BEHIND. TIP DEPTH vs PORE PRESSURE -5 U (m. of water) 0 5 10 15 J I L SOIL PROFILE C t 5 0 0 + 0 0 ( 82 DAYS a f t e r ) VIRGIN AREA #1 ' C L 5 0 0 + 0 0 ( 2 0 9 DAYS a f t e r ) Hydrostotic P.W.P. HBTZlPv pr«**wr« m«OBwr*4 BEHIND TIP SAND FILL SLT WEDIUU DENSE SANO CLAYEY SLT F i g u r e 23 - E f f e c t o f B e h i n d T i p p . w . p . W i t h Time 209 Days A f t e r 80 1 0 . 2 . 4 F r i c t i o n R a t i o The f r i c t i o n r a t i o was chosen t o a t tempt t o c o n f i r m the m i x i n g o f t h e sand f i l l and s i l t i n d i c a t e d by t h e cone b e a r i n g and s l e e v e f r i c t i o n . 1 0 . 2 . 4 . 1 Time E f f e c t The e f f e c t o f t h e f r i c t i o n r a t i o w i t h t ime i s shown i n F i g u r e 24. T h i s shows t h a t the f r i c t i o n r a t i o e f f e c t i v e l y does not change from b e f o r e and a f t e r and a l s o w i t h t i m e . T h i s i s t r u e f o r t h e sand f i l l and medium dense sand l a y e r s b u t not t h e s i l t l a y e r . T h i s can be c l e a r l y seen by t h e peak i n d i c a t e d a t around 2.75m b e f o r e t r e a t m e n t and d i s a p p e a r i n g a f t e r t r e a t m e n t . However, t h e s i l t l a y e r from 4m t o 5m i s s t i l l e v i d e n t but t o a l e s s e r e x t e n t . A g a i n , t h i s p o i n t s t o t h e m i x i n g e f f e c t o f t h e p r o b e . 1 0 . 2 . 4 . 2 D i s t a n c e E f f e c t The d i s t a n c e e f f e c t i s no t d e p i c t e d i n a s e r i e s o f f i g u r e s s i n c e i t i s a r e p e a t o f t h e cone b e a r i n g and s l e e v e f r i c t i o n , and the e v i d e n c e can be seen i n t h e CPTU p r o f i l e s c o n t a i n e d i n t h e A p p e n d i x . C L 500+00 (before vcomp) • C L 500+00 (67 DAYS after) C L 500+00 (82 DAYS after) • • • • • C L 500+00 (209 DAYS after) F i g u r e 24 - E f f e c t o f F r i c t i o n R a t i o W i t h Time 67, 82, and 209 Days A f t e r 82 10.3 DMT Parameters 1 0 . 3 . 1 I n t r o d u c t i o n The DMT was o n l y c a r r i e d out a t one s p e c i f i c t ime a f t e r v i b r o c o m p a c t i o n , hence t h e r e a r e no r e l a t i v e t ime o r d i s t a n c e e f f e c t s . T h u s , t h e DMT programme i n v o l v e d a t e s t i n V i r g i n A r e a #1 and two t e s t s on t h e c e n t r e l i n e between probe h o l e s w i t h one membrane f a c i n g E a s t and t h e o t h e r f a c i n g N o r t h . T h i s was done t o i n v e s t i g a t e i f t h e T r i S t a r probe d e n s i f i e d t h e s o i l e q u a l l y i n t h e h o r i z o n t a l p l a n e . The a c t u a l t e s t i n g was c a r r i e d out 111 days a f t e r v i b r o c o m p a c t i o n . The t ime was d i c t a t e d by equipment a v a i l a b i l i t y and s i t e a c c e s s . 1 0 . 3 . 2 Parameter R e s u l t s The s e r i e s o f F i g u r e s 25, 26, 27, 28, and 29 show the e f f e c t o f v i b r o c o m p a c t i o n on t h e f o l l o w i n g p a r a m e t e r s : X - P 0 2. P 1 3. M a t e r i a l Index, I D 4. H o r i z o n t a l S t r e s s Index, K D 5. D i l a t o m e t e r Modulus , E D I t can be seen t h a t a l l o f them e x h i b i t t h e same b e h a v i o u r i n b o t h t h e E a s t and N o r t h d i r e c t i o n s . T h u s , i t may be assumed t h a t t h e method o f v i b r o c o m p a c t i o n by the T r i S t a r probe i s i s o t r o p i c , i . e . i t does d e n s i f y t h e s o i l e q u a l l y i n t h e h o r i z o n t a l p l a n e . DEPTH vs P 0 83 Po (bar) PROFILE SAND FILL SILT MEDIUM DENSE SAND CLAYEY SILT C L 500+00 (DMT facing East) — — C L 500+00 (DMT facing North) VIRGIN AREA #1 NOTE: Test date 111 DAYS after. F i g u r e 25 - P Q V e r s u s Depth B e f o r e and A f t e r D e n s i f i c a t i o n D E P T H vs PT 84 Pi (bar) 10 20 _L 40 SOIL PROFILE SAND FILL SILT MEDIUM DENSE SAND CLAYEY SILT C L 500+00 (DMT facing East) C L 500+00 (DMT facing North) VIRGIN AREA #1 NOTE: Test date 111 DAYS after. F i g u r e 26 - P , V e r s u s Depth B e f o r e and A f t e r D e n s i f i c a t i o n DEPTH vs l D 85 C L 500+00 (DMT facing East) * * * * * C L 500+00 (DMT facing North) VIRGIN AREA #1 NOTE: Test date 111 DAYS after. F i g u r e 27 - I V e r s u s Depth B e f o r e and A f t e r D e n s i f i c a t i o n DEPTH vs K D 86 C L 500+00 (DMT facing East) • • • • « C L 500+00 (DMT facing North) VIRGIN AREA #1 NOTE: Test date 111 DAYS after. F i g u r e 28 - K D V e r s u s Depth B e f o r e and A f t e r D e n s i f i c a t i o n DEPTH vs E D 8" r fw \ SOIL t-D i D a r j P R O F I L E 0 2 0 0 4 0 0 6 0 0 8 0 0 1 0 0 0 SAND FILL SILT MEDIUM DENSE SAND CLAYEY SILT C L 500+00 (DMT facing East) • • • • • C L 500+00 (DMT facing North) VIRGIN AREA #1 NOTE: Test date 111 DAYS after. F i g u r e 29 - E D V e r s u s D e p t h B e f o r e a n d A f t e r D e n s i f i c a t i o n 88 By comparing the DMT p r o f i l e e x c e p t , I D , t o t h o s e o f the CPTU i t can be seen t h a t t h e DMT c o n f i r m s t h e s o i l h o r i z o n s found by t h e CPTU. Depending on which parameter i s chosen f o r t h e medium dense sand l a y e r each has been i n c r e a s e d from between 3 t imes (shown by K D ) and 4 t i m e s (shown by P Q , P l f and E D ) which compares f a v o u r a b l y w i t h t h a t found by t h e CPTU. The e f f e c t o f v i b r o c o m p a c t i o n s t o p s a t 10m, t h e l i m i t o f the probe and the c l a y e y s i l t i s u n a f f e c t e d . As ment ioned , t h e above i s t r u e f o r a l l t h e parameters e x c e p t , I D . T h i s i s t h e M a t e r i a l Index , w h i c h i s used f o r s o i l i d e n t i f i c a t i o n and hence s h o u l d no t change i f t h e s o i l t y p e i s no t c h a n g i n g . T h i s i s e s s e n t i a l l y t r u e except f o r t h e sand f i l l and s i l t which under went m i x i n g . T h i s i s c l e a r l y shown by t h e b e f o r e peak a t 2.5m d i s a p p e a r i n g a t t h e a f t e r s t a g e w h i l e t h e peaks a t 4m and 6m remain e s s e n t i a l l y t h e same. The peaks r e p r e s e n t s i l t y m a t e r i a l and s i n c e t h e sand f i l l mixes w i t h t h e s i l t from 2.5m t o 4m t h e s o i l t y p e i s changed. T h u s , t h e m i x i n g i d e a has been c o n f i r m e d . The above a l s o backs up t h e f i n d i n g s o f t h e f r i c t i o n r a t i o d e r i v e d from the CPTU r e s u l t s . Hence b o t h c o r r e c t l y i d e n t i f y t h e s o i l t y p e i n d e p e n d e n t l y o f p o s s i b l e changes t o d e n s i t y , m o d u l i and s t r e s s c o n d i t i o n s . 89 10.4 SCPTU Parameters 1 0 . 4 . 1 I n t r o d u c t i o n L i k e t h e DMT, t h e SCPTU was o n l y c a r r i e d out a t one s p e c i f i c t ime a f t e r v i b r o c o m p a c t i o n , hence t h e r e a r e no r e l a t i v e t ime o r d i s t a n c e e f f e c t s . The SCPTU programme i n v o l v e d a t e s t on t h e c e n t r e l i n e o f v i b r o c o m p a c t i o n a t c h a i n a g e 600 + 00 b e f o r e v i b r o c o m p a c t i o n , one i n V i r g i n A r e a #1 and one on t h e c e n t r e l i n e a t c h a i n a g e 500 + 0 0 , 82 days a f t e r v i b r o c o m p a c t i o n . The t e s t a t c h a i n a g e 600 + 00 was c a r r i e d out by ConeTec . The d a t a f o r t h e f i r s t 4m i s m i s s i n g as i t i s e rroneous due t o t h e l a r g e s o i l v a r i a b i l i t y o v e r the s m a l l d e p t h . 1 0 . 4 . 2 Shear Modulus The p r o f i l e o f maximum shear modulus , G j ^ ^ , v e r s e s depth i s shown i n F i g u r e 30. I t was d e t e r m i n e d from t h e measured s h e a r wave v e l o c i t i e s d u r i n g the s e i s m i c p i e z o c o n e . The method has been d e s c r i b e d a l r e a d y i n s e c t i o n 9 . 2 . 2 . 3 . The r e s u l t s show no d i f f e r e n c e i n f o r t h e f i r s t 3m o f t r e a t e d s o i l , i . e . 5-8m. A f t e r t h e 8m d e p t h an i n c r e a s e o f 10-15 MPa i s n o t e d u n t i l t h e 10m d e p t h , which was the l i m i t o f the probe p e n e t r a t i o n . DEPTH vs GMAX 90 2 0 GMAX (MPa) 40 6 0 8 0 100 SOIL PROFILE SAND FILL C L 500+00 (82 DAYS after) VIRGIN AREA #1 C L 600+00 (before vcomp) F i a u r e 30 - G„ V e r s u s Depth B e f o r e and A f t e r D e n s i f i c a t i o n T h e r e i s no g a i n shown f o r t h e 5 .0 - 8.0m l a y e r as o p e r a t i o n a l problems were e n c o u n t e r e d , i . e . , t h e 6.5m t e s t i s i n c o r r e c t and t h e 7.5m t e s t i s m i s s i n g . - T h e r e f o r e , because o f t h e p o o r d a t a no c o n c l u s i o n can be made about t h e e f f e c t i v e n e s s o f t h e SCPTU t o measure changes i n G j ^ ^ , b r o u g h t about by the v i b r o c o m p a c t i o n p r o c e s s . 10 .5 LSCPTU Parameters 1 0 . 5 . 1 I n t r o d u c t i o n The LSCPTU was o n l y c a r r i e d out a t one s p e c i f i c t ime a f t e r v i b r o c o m p a c t i o n , hence t h e r e a r e no r e l a t i v e t ime o r d i s t a n c e e f f e c t s . The LSCPTU programme i n v o l v e d a t e s t on t h e c e n t r e l i n e o f v i b r o c o m p a c t i o n a t c h a i n a g e 500 + 00 a f t e r t r e a t m e n t and one i n V i r g i n A r e a #1. The t e s t s were c a r r i e d out 204 days a f t e r d e n s i f i c a t i o n , t h e t i m e a t which t h e LSCPTU became o p e r a t i o n a l . 1 0 . 5 . 2 L a t e r a l S t r e s s The p e n e t r a t i o n l a t e r a l s t r e s s was measured t o f i n d out how i t was a f f e c t e d by v i b r o c o m p a c t i o n and t o compare i t t o the v e r t i c a l s t r e s s . The p r o f i l e o f l a t e r a l s t r e s s v e r s u s d e p t h i s shown i n F i g u r e 31. T h i s i n d i c a t e s a l l t h e r e l e v a n t s o i l b o u n d a r i e s and t h e m i x i n g o f the sand f i l l w i t h t h e s i l t . The p r o f i l e i s s i m i l a r t o t h o s e g i v e n by t h e o t h e r i n - s i t u t e s t s . The DEPTH vs LATERAL S T R E S S S igma h (kPa) PROFILE 1000 SAND FILL SILT MEDIUM DENSE SAND CLAYEY SILT C L 500+00 (204 DAYS after) VIRGIN AREA #1 F i g u r e 31 - L a t e r a l S t r e s s V e r s e s Depth B e f o r e and A f t e r D e n s i f i c a t i o n medium dense sand l a y e r shows an i n c r e a s e o f between 50%-100%. A g a i n , the p r o f i l e r e t u r n s t o i t s v i r g i n s tate- around the 10m d e p t h and no change i s seen i n t h e c l a y e y s i l t . 10 .6 C o n c l u s i o n s T h i s c h a p t e r has shown t h a t t h e medium dense sand l a y e r was s i g n i f i c a n t l y compacted, i . e . an i n c r e a s e o f 200-400%. The CPTU parameters o f cone b e a r i n g and s l e e v e f r i c t i o n i n d i c a t e d t h i s i n c r e a s e which t h e DMT parameters P 0 , P^, K D , and E D c o n f i r m e d . The CPTU has shown t h a t the compact ion e f f e c t i s t ime dependent and i t d e c r e a s e s w i t h d i s t a n c e from the probe h o l e . A l s o , t h e p o r e water p r e s s u r e measured by t h e CPTU does not change from b e f o r e and a f t e r d e n s i f i c a t i o n . I t has been shown t h a t the CPTU parameter f r i c t i o n r a t i o and t h e m a t e r i a l index from t h e DMT a r e good s o i l t y p e i n d i c a t o r s which a r e independent o f changes i n r e l a t i v e d e n s i t y , s t i f f n e s s and s t r e s s c o n d i t i o n s due t o v i b r o c o m p a c t i o n . The s e i s m i c p i e z o c o n e r e s u l t s were i n c o n c l u s i v e so no c o n c l u s i o n s c o u l d be made as t o i t s a b i l i t y t o measure the e f f e c t o f v i b r o c o m p a c t i o n on t h e s h e a r modulus . The l a t e r a l s t r e s s cone measured an i n c r e a s e i n the p e n e t r a t i o n l a t e r a l s t r e s s o f 50 - 100%. A l l o f t h e p e n e t r a t i o n t e s t s except t h e SCPTU i n d i c a t e d t h a t p a r t o f t h e s i l t l a y e r was improved by t h e sand f i l l above f a l l i n g down and m i x i n g w i t h t h e s i l t . 94 11 .0 INTERPRETATION OF THE RESULTS AND GEOTECHNICAL  PARAMETERS 11 .1 I n t r o d u c t i o n The l a s t c h a p t e r has shown t h a t t h e T r i S t a r probe s i g n i f i c a n t l y i n c r e a s e d t h e p e n e t r a t i o n r e s i s t a n c e i n the medium dense sand l a y e r . The f o l l o w i n g c h a p t e r i n v e s t i g a t e s t h e changes i n s o i l parameters caused by v i b r o c o m p a c t i o n . To h e l p i n t h i s p r o c e s s , the d a t a has been smoothed by f i l t e r i n g i n o r d e r t o ge t g e n e r a l t r e n d s . As t h e o v e r a l l s o i l p r o f i l e has o n l y been i n v e s t i g a t e d , each s o i l l a y e r i s s c r u t i n i z e d by u s i n g t h e CPTU parameter cone b e a r i n g . T h e r e a f t e r , the v a r i o u s g e o t e c h n i c a l p a r a m e t e r s a r e compared. 11.2 CPTU R e s u l t s 1 1 . 2 . 1 F i l t e r i n g Due t o t h e p r e s e n c e o f v a r i o u s l e n s e s o f d i f f e r e n t s o i l t y p e s w i t h i n each o f t h e s o i l l a y e r s , i t was d i f f i c u l t t o p i c k out g e n e r a l t r e n d s and t o make c o m p a r i s o n s . T h e r e f o r e , i t was d e c i d e d t o f i l t e r t h e CPTU cone b e a r i n g d a t a i n o r d e r t o smooth out t h e p r o f i l e . The program U . B . C . - F I L T d e v e l o p e d a t U . B . C . by D . S . Wickremensinghe under t h e s u p e r v i s i o n o f D r . R . G . Campane l la was used f o r t h i s purpose (Wickremensinghe and C a m p a n e l l a , 1988) . The program f i l t e r s out e x t r e m i t i e s o r anomal i e s i n the d a t a . T h i s i s based on s e v e r a l o p t i o n s such as mean o r median f i l t e r i n g , c h o i c e o f i n t e n s i t y o f f i l t e r i n g , and 95 s e l e c t i o n o f removal o r rep lacement o f d a t a f a l l i n g o u t s i d e t h e a c c e p t a b l e r e g i o n . However, i t must be n o t e d t h a t good e n g i n e e r i n g judgement be e x e r c i s e d when f i l t e r i n g out d a t a . T h i s i s f i r s t l y t o a v o i d t h e p o s s i b i l i t y o f l o s i n g genuine d a t a and s e c o n d l y , f i l t e r i n g i s v e r y s i t u a t i o n dependent . A compar i son o f b e f o r e and a f t e r f i l t e r i n g i s shown i n F i g u r e 32. The f i l t e r i n g was c a r r i e d out u s i n g t h e median w i t h 10 d a t a p o i n t s i n a g r o u p , a degree o f f i l t e r i n g e q u a l t o 3 and u s i n g n e i g h b o u r i n g u n f i l t e r e d d a t a p o i n t s . T h i s p r o d u c e s a smoother p r o f i l e w i t h l e s s v a r i a b i l i t y hence the t r e n d i s more e a s i l y r e c o g n i s a b l e . F o r f u r t h e r i n f o r m a t i o n a d e t a i l e d d e s c r i p t i o n o f t h e program U . B . C . -F I L T and i t s use i s g i v e n by Wickremensinghe and C a m p a n e l l a , 1988. 1 1 . 2 . 2 Time Dependent B e h a v i o u r I n o r d e r t o a n a l y z e t h e t ime dependent s o i l b e h a v i o u r f o r each l a y e r a p l o t o f cone b e a r i n g v e r s u s t i m e has been p r o d u c e d f o r each o f t h e 3 l a y e r s . These d e p i c t the p r o g r e s s o f cone b e a r i n g w i t h measurements t a k e n a t : b e f o r e , 6, 67, 82, and 209 days a f t e r v i b r o c o m p a c t i o n . 1 1 . 2 . 2 . 1 Sand F i l l L a y e r The p l o t o f cone b e a r i n g v e r s u s t ime i s shown i n F i g u r e 33. As i n d i c a t e d on t h e f i g u r e , t h e s e c t i o n o f l a y e r i n v e s t i g a t e d extends from 1.125m t o 2.625m. A l t h o u g h the C L 500+00 before (unfiltered) C L 500+00 before (f i l tered) F i g u r e 32 - F i l t e r e d and U n f i l t e r e d Cone B e a r i n g V e r s u s Depth TIME vs C O N E BEARING (SAND FILL LAYER) 350 75 100 125 150 175 Time After Densification (days) 250 F i g u r e 33 - Time Versus Cone B e a r i n g f o r Sand F i l l L a y e r 98 s a n d f i l l l a y e r e x t e n d s f r o m t h e s u r f a c e t o a r o u n d 2.5m, t h e d e p t h o f 1.125m was c h o s e n a s t h e s t a r t , a s ab o v e t h i s d e p t h t h e s a n d f i l l h a d b e e n v i b r o c o m p a c t e d b y a s u r f a c e r o l l e r . T h e p l o t i n d i c a t e s t h a t t h e most r a p i d g a i n o c c u r s d u r i n g t h e f i r s t 6 d a y s , u n t i l p e a k i n g somewhere b e t w e e n 6 and 82 d a y s , t h e r e a f t e r r e a c h i n g a p l a t e a u . 11.2.2.2 S i l t L a y e r The p l o t o f c o n e b e a r i n g v e r s u s t i m e i s shown i n F i g u r e 34. A s i n d i c a t e d on t h e f i g u r e , t h e s e c t i o n o f l a y e r i n v e s t i g a t e d e x t e n d s f r o m 2.875m t o 3.875m. T h i s i s a c t u a l l y a c o m p o s i t e p i c t u r e a s i t shows t h e m i x i n g o f t h e s a n d f i l l a n d s i l t . A s w i t h t h e p u r e s a n d f i l l l a y e r t h e t o p s e c t i o n e x h i b i t s t h e same c o n e b e a r i n g i n c r e a s e p a t t e r n . T h e n on m o v i n g d e e p e r , t h i s c h a r a c t e r i s t i c i s g r a d u a l l y l e s s e n e d u n t i l t h e s i l t l a y e r i s r e a c h e d a t 3.875m. Hence, i t c a n be c o n c l u d e d t h a t , k n o w i n g b e f o r e h a n d t h a t t h e s i l t l a y e r e x t e n d e d f r o m 2.625m t o 5m i t h a s now b e e n s i g n i f i c a n t l y i m p r o v e d f r o m 2.625 t o 3.875m.. A l s o , t h e e f f e c t o f m i x i n g g r a d u a l l y r e d u c e s f r o m 2.625m t o 3.875m. TIME vs C O N E B E A R I N G ( S I L T L A Y E R ) 3 5 0 - i 1 1 1 1 ~ i 1 r 2 . 8 7 5 m d e p t h . 3 0 0 - • * H * - ~ . 3 . 1 2 5 m d e p t h . — — 3 . 3 7 5 m d e p t h . 3 . 6 2 5 m d e p t h . 2 5 0 - CHB-B-EH3 3 . 8 7 5 m d e p t h . NOTE: (1) The data is filtered using the median. 2 0 0 -2 2 5 2 5 0 Time After Densif ication (days) F i g u r e 34 - Time Versus Cone B e a r i n g f o r S i l t L a y e r VO VO 100 1 1 . 2 . 2 . 3 Medium Dense Sand L a y e r The p l o t o f cone b e a r i n g v e r s u s t ime i s shown i n F i g u r e 35. As i n d i c a t e d on t h e f i g u r e , t h e s e c t i o n o f l a y e r i n v e s t i g a t e d extends from 7.125m t o 9.375m. O n l y t h i s p o r t i o n was chosen as i t c o n t a i n e d t h e l e a s t v a r i a b l e d a t a . A g a i n t h e p l o t shows t h e r a p i d i n c r e a s e i n cone b e a r i n g d u r i n g t h e f i r s t 6 days a f t e r which t h e g a i n i s r educed u n t i l 67 d a y s . A t t h i s p o i n t t h e g a i n i n c r e a s e s v e r y r a p i d l y t o a peak a t 82 d a y s , a f t e r which t h e g a i n d e c r e a s e s . T h i s s t e p wise p r o f i l e does no t seem q u i t e c o r r e c t as one would expec t a smoother g a i n a f t e r t h e r a p i d one up t o 6 d a y s . As d i s c u s s e d i n t h e c h a p t e r o f t h e CPTU r e s u l t s w i t h t ime t h e cause may be due t o t h e ground water l e v e l b e i n g h i g h e r a t the 82 day t e s t t h a n the r e s t due t o a d i f f e r e n t t i d e l e v e l . 11 .2 .2.4 C o n c l u s i o n s I t may be c o n c l u d e d t h a t f o r t h i s p a r t i c u l a r s i t e and the s o i l s i n v e s t i g a t e d , t h a t t h e i n c r e a s e i n cone b e a r i n g f o l l o w s a c u r v e d shape w i t h a peak o c c u r r i n g between 6 and 82 days and i s the case f o r each l a y e r . The d e c r e a s e i n cone b e a r i n g a f t e r 82 days i s f e l t t o be a r t i f i c i a l due t o t i d a l change . Hence i t i s sugges ted t h a t t h e cone b e a r i n g g a i n would have i n s t e a d p l a t e a u e d . TIME vs CONE BEARING (MEDIUM DENSE SAND LAYER) 350 50 75 100 125 150 175 Time After Densification (days) F i g u r e 35 - Time V e r s u s Cone B e a r i n g f o r Medium Dense Sand L a y e r 225 250 102 1 1 . 2 . 3 D i s t a n c e Dependent B e h a v i o u r In o r d e r t o a n a l y z e the d i s t a n c e dependent b e h a v i o u r f o r each l a y e r , a p l o t o f cone b e a r i n g v e r s u s d i s t a n c e has been p r o d u c e d f o r each o f t h e 3 l a y e r s . These d e p i c t the r e l a t i o n s h i p w i t h measurements t a k e n a t t h e c e n t r e l i n e o f v i b r o c o m p a c t i o n , lm, 2m, and 3m away. As no d a t a i s a v a i l a b l e f o r t h e 4m d i s t a n c e , t h e c e n t r e l i n e b e f o r e d a t a has been used t o show t h a t by 3m, t h e s o i l has r e t u r n e d t o i t s o r i g i n a l s t a t e . However, i t has s i n c e been r e a l i z e d t h a t the l i n e o f t e s t i n g was wrong ly p o s i t i o n e d as i t s h o u l d have s t a r t e d a t a probe h o l e . T h i s means t h a t the d e c r e a s e i n cone b e a r i n g d e p i c t e d may be on t h e h i g h s i d e as t h e s o i l t e s t e d has been a f f e c t e d by more t h a n one probe h o l e . T h i s i s e v i d e n t i n each o f t h e l a y e r s as t h e g r a d i e n t i s l e s s f o r t h e f i r s t metre from t h e probe h o l e , t h e r e a f t e r becoming more u n i f o r m as would be e x p e c t e d . 1 1 . 2 . 3 . 1 Sand F i l l L a y e r The p l o t o f cone b e a r i n g v e r s u s d i s t a n c e i s shown i n F i g u r e 36. As i n d i c a t e d on t h e f i g u r e , t h e s e c t i o n o f the l a y e r i n v e s t i g a t e d extends from 1.375m t o 2.125m. A g a i n t h e lower s t a r t i n g depth was chosen due t o t h e sand above b e i n g e f f e c t e d by a v i b r a t i n g s u r f a c e r o l l e r . The p l o t shows t h e d e c r e a s e o f cone b e a r i n g w i t h d i s t a n c e form t h e c e n t r e l i n e . Good agreement i s shown f o r t h e whole l a y e r i n v e s t i g a t e d . By the 3m d i s t a n c e no e v i d e n c e o f an i n c r e a s e i n cone b e a r i n g i s i n d i c a t e d . DISTANCE vs C O N E B E A R I N G (SAND FILL LAYER) 350 3 0 0 -2 5 0 -1.375m depth. 1.625m depth. 1.875m depth. 2.125m depth. NOTE: (1) The data is filtered using the median. (2) The test was carried out 82 DAYS after densificatioh. (3) The 4m distance is the Q. before densification. 1 2 3 Distance (m) F i g u r e 36 - D i s t a n c e V e r s u s Cone B e a r i n g f o r Sand F i l l L a y e r o 104 T h e r e f o r e , f o r the sand f i l l l a y e r , t h e zone o f i n f l u e n c e f o r t h e T r i S t a r probe i s a r a d i u s o f about 2m. 1 1 . 2 . 3 . 2 S i l t L a y e r The p l o t o f cone b e a r i n g v e r s u s d i s t a n c e i s shown i n F i g u r e 37. As i n d i c a t e d on the f i g u r e , t h e s e c t i o n o f the l a y e r i n v e s t i g a t e d extends from 2.375m t o 4.125m. As w i t h t h e t i m e p l o t t h i s i s a compos i te p i c t u r e , showing t h e m i x i n g o f t h e sand f i l l w i t h t h e s i l t . The t o p s e c t i o n o f t h e p l o t shows t h e same p a t t e r n as t h e sand f i l l , f o r m e r l y s i l t , as t h e cone b e a r i n g g r a d u a l l y d e c r e a s e s w i t h d i s t a n c e from t h e c e n t r e l i n e . The cone b e a r i n g a l s o d e c r e a s e s v e r t i c a l l y w i t h d e p t h , i n d i c a t i n g the m i x i n g e f f e c t . The t r e n d c o n t i n u e s downwards u n t i l the s i l t l a y e r i s r eached a t which p o i n t i t remains r e l a t i v e l y c o n s t a n t . T h u s , t h e T r i S t a r probe has improved t h e f i r s t 1.5m o f t h e s i l t l a y e r . No e v i d e n c e o f cone b e a r i n g g a i n i s seen a f t e r 3m f o r t h e e n t i r e zone . T h e r e f o r e , f o r the s i l t l a y e r , t h e zone o f i n f l u e n c e f o r t h e T r i S t a r probe i s a r a d i u s o f about 2m. 1 1 . 2 . 3 . 3 Medium Dense Sand L a y e r The p l o t o f cone b e a r i n g v e r s u s d i s t a n c e i s shown i n F i g u r e 38. As i n d i c a t e d on t h e f i g u r e , t h e s e c t i o n o f the l a y e r i n v e s t i g a t e d extends from 6.625m t o 9.125m, s i n c e i t c o n t a i n e d the l e a s t v a r i a b l e d a t a . DISTANCE vs CONE BEARING ( S I L T L A Y E R ) o 3 5 0 3 0 0 -2 5 0 -2 0 0 -1 5 0 -1 0 0 -5 0 -0 • • » • » 2 . 3 7 5 m d e p t h . 2 . 6 2 5 m d e p t h . 2 . 8 7 5 m d e p t h . 3 . 1 2 5 m d e p t h . P P O O P 3 . 3 7 5 m d e p t h . A A A A A 3 . 6 2 5 m d e p t h , v-o-v-e-o 3 . 8 7 5 m d e p t h . * * * * * 4 . 1 2 5 m d e p t h . NOTE : M) The data is filtered using the median. (2; The test was carried out 82 DAYS after densification. (3) The 4m distance is the CL before densification. 2 3 Distance (m) F i g u r e 37 D i s t a n c e V e r s u s Cone B e a r i n g f o r S i l t L a y e r o DISTANCE vs CONE BEARING ( M E D I U M D E N S E S A N D L A Y E R ) 3 5 0 NOTE: (1) The data is filtered using the median. (2) The test was carried out 82 DAYS after densification. (3) The 4m distance is the CL before densification. 1 6 . 6 2 5 m 6 . 8 7 5 m 7 . 1 2 5 m 7 . 3 7 5 m p p p o n 7 . 8 7 5 m A A A A A 8 . 1 2 5 m o o o o o 8 . 3 7 5 m * * * * * 8 . 6 2 5 m ' ' i i i 8 . 8 7 5 m » * * » x 9 . 1 2 5 m depth, depth, depth, depth, depth, depth, depth, depth, depth, depth. Distance (m) F i g u r e 38 D i s t a n c e V e r s u s Cone B e a r i n g f o r Medium Dense Sand Layer H O CM 107 The p l o t shows t h e g r a d u a l d e c r e a s e o f cone b e a r i n g w i t h d i s t a n c e from t h e c e n t r e l i n e . T h i s i s t h e most i m p o r t a n t l a y e r as i t was i t s s u s c e p t i b i l i t y t o l i q u e f a c t i o n d u r i n g a s t r o n g ear thquake t h a t r e q u i r e d i t t o be v i b r o c o m p a c t e d . The p l o t i n d i c a t e s t h a t improvement was a c h i e v e d and i n c r e a s e d t h e cone b e a r i n g up t o a d i s t a n c e o f 3m away from the c e n t r e l i n e . T h e r e f o r e , as w i t h the p r e c e d i n g l a y e r s t h e zone o f i n f l u e n c e f o r t h e T r i S t a r probe i s a r a d i u s o f about 2m. T h i s i s q u i t e s i g n i f i c a n t as t h e same t e s t c a r r i e d out by t h e c o n t r a c t o r (Massarsch and V a n n e s t e , 1988) 6 days a f t e r v i b r o c o m p a c t i o n showed o n l y a s l i g h t i n c r e a s e a t lm from t h e c e n t r e l i n e f o r t h e medium dense sand l a y e r ( F i g u r e 17 ) . However, the p e r c e n t a g e d i f f e r e n c e between 6 and 82 days f o r t h e lm d i s t a n c e i s a p p r o x i m a t e l y 190%. T h i s i n d i c a t e s t h a t t h e s o i l o u t s i d e t h e a r e a e n c l o s e d by t h e probe h o l e s undergoes a s l o w e r i n c r e a s e o f cone b e a r i n g w i t h t i m e , as would be e x p e c t e d , because o f t h e r e d u c e d compact ion e f f e c t . 1 1 . 2 . 3 . 4 C o n c l u s i o n s I t may be c o n c l u d e d t h a t f o r t h i s p a r t i c u l a r s i t e and the s o i l s i n v e s t i g a t e d , t h a t t h e cone b e a r i n g g a i n e s s e n t i a l l y f i n i s h e s a t a d i s t a n c e o f 3m from t h e c e n t r e l i n e o f d e n s i f i c a t i o n . T h u s , t h e T r i S t a r probe has a zone o f i n f l u e n c e o f about 2m. The s o i l beyond t h e a r e a c o n t a i n e d by t h e probe h o l e s undergoes a s l o w e r i n c r e a s e i n cone b e a r i n g . 108 11.3 R e l a t i v e D e n s i t y 1 1 . 3 . 1 I n t r o d u c t i o n Recent r e s e a r c h has shown t h a t t h e s t r e s s - s t r a i n and s t r e n g t h c h a r a c t e r i s t i c s o f a c o h e s i o n l e s s s o i l a r e too complex t o be r e p r e s e n t e d o n l y by t h e r e l a t i v e d e n s i t y o f t h e s o i l . T h e r e has been much d i s c u s s i o n on the d i f f i c u l t i e s o f u n i q u e l y d e t e r m i n i n g t h e maximum and minimum sand d e n s i t i e s f o r c a l c u l a t i o n o f r e l a t i v e d e n s i t y . Recent work w i t h cone pene trometers i n l a r g e c a l i b r a t i o n chambers has a t tempted t o d e v e l o p r e l a t i o n s h i p s between cone b e a r i n g , e f f e c t i v e s t r e s s and r e l a t i v e d e n s i t y . A l t h o u g h no un ique r e l a t i o n s h i p e x i s t s between t h e s e p a r a m e t e r s , u s e f u l r e l a t i o n s h i p s have been d e r i v e d i f sand c o m p r e s s i b i l i t y i s t a k e n i n t o account and i f cone b e a r i n g i s c o r r e l a t e d w i t h t h e i n - s i t u h o r i z o n t a l e f f e c t i v e s t r e s s . One such r e l a t i o n s h i p g i v e n by B a l d i e t a l . (1982) i s shown i n F i g u r e 39. T h i s r e l a t i o n s h i p a p p l i e s t o n o r m a l l y c o n s o l i d a t e d , uncemented and unaged q u a r t z s a n d s , o f moderate c o m p r e s s i b i l i t y . The r e l a t i o n s h i p can a l s o be a p p l i e d t o o v e r c o n s o l i d a t e d sands i f t h e i n - s i t u h o r i z o n t a l s t r e s s i s used i n s t e a d o f t h e v e r t i c a l s t r e s s . I t i s c o n s i d e r e d t h a t the sands found a t t h e A n n a c i s I s l a n d s i t e a r e s i m i l a r i n n a t u r e t o t h e T i c i n o t e s t sands from which t h e r e l a t i o n s h i p s o f B a l d i e t a l . (1982) were d e v e l o p e d , and t h e r e l a t i o n s h i p s a r e m e a n i n g f u l f o r the sands i n q u e s t i o n . F i g u r e 39 R e l a t i v e D e n s i t y R e l a t i o n s h i p f o r Uncemented and Unaged Q u a r t z Sands (adapted from B a l d i e t a l . 1982) 110 1 1 . 3 . 2 Time E f f e c t The e f f e c t o f r e l a t i v e d e n s i t y as a f u n c t i o n o f t i m e i s shown i n F i g u r e 40. The r e l a t i v e d e n s i t y e x h i b i t s the same b e h a v i o u r i n the sand f i l l and s i l t l a y e r s as d i d t h e cone b e a r i n g , i . e . the m i x i n g e f f e c t . T h i s i s e v i d e n t by t h e bottom o f the sand f i l l l o c a t e d a t 2m b e f o r e v i b r o c o m p a c t i o n was t h e n found a t 4m a f t e r v i b r o c o m p a c t i o n . I n t h e medium dense s a n d , t h e r e l a t i v e d e n s i t y shows the same p r o g r e s s i v e b u i l d up as cone b e a r i n g and s l e e v e f r i c t i o n w i t h t h e r e l a t i v e d e n s i t y b e i n g i n c r e a s e d from 55% t o 85-90%. A g a i n , t h e r e i s t h e unexpected peak a t 82 d a y s , t h e r e a s o n f o r which has been e x p l a i n e d i n s e c t i o n 1 0 . 2 . 1 . 1 . S i n c e no account has been made o f p o s s i b l e i n c r e a s e s i n l a t e r a l s t r e s s brought about by t h e d e n s i f i c a t i o n p r o c e s s , t h e r e l a t i v e d e n s i t y so e v a l u a t e d r e p r e s e n t s an upper bound v a l u e . 1 1 . 3 . 3 D i s t a n c e E f f e c t The e f f e c t o f r e l a t i v e d e n s i t y as a f u n c t i o n o f d i s t a n c e lm, 2m and 3m from t h e c e n t r e l i n e o f v i b r o c o m p a c t i o n i s shown i n F i g u r e 41. The a s p e c t o f t h e sand f i l l m i x i n g w i t h s i l t can be seen q u i t e c l e a r l y i f one observes t h e s e r i e s o f f i g u r e s . The sand f i l l p r o f i l e g r a d u a l l y moves back from i t s peak v a l u e o f 90% from 0 - 4m (top l e f t graph) t o a lmos t i t s v i r g i n DEPTH vs RELATIVE DENSITY D, (*) 40 60 DEPTH vs RELATIVE DENSITY 0, (*) 100 111 SOIL PROFILE SAND FILL SILT UEDIUU DENSE SANO CLAYEY SLT Q. 500+00 (67 DAYS ofter) Ct 500+00 (before vcomp) DEPTH vs RELATIVE DENSITY d . 500+00 (67 DAYS ofter) Ct 500+00 (before vcomp) Ct 500+00 (82 DAYS after) Dr (*) 40 60 100 SOIL PROFILE SANO FU. S S J UEDIUU DENSE SANO CLAYEY SILT C\ 500+00 (82 DAYS ofter) Ct 500+00 (before vcomp) Ct 500+00 (209 DAYS ofter) F i g u r e 40 E f f e c t o f R e l a t i v e D e n s i t y W i t h Time 67, 82, and 209 Days A f t e r DEPTH vs RELATIVE DENSITY Dr (*) 40 60 100 DEPTH vs RELATIVE DENSITY 100 112 SOIL PROFILE SANO FILL SILT MEDIUM DENSE SAND CLAYEY SLT C\ 500+00 C t 500+00 (before vcomp) DEPTH vs RELATIVE DENSITY Ct 500+00 C t 500+00 (before vcomp) 1m SOUTH OF C L 500+00 DEPTH vs RELATIVE DENSITY Dr (*) C L 500+00 C L 500+00 (before vcomp) 2m SOUTH OF C t 500+00 100 Dr (*) 40 60 C L 500+00 C L 500+00 (before vcomp) 3m SOUTH OF C L 500+00 100 SOIL PROFILE SAND FILL SLT MEDIUM DENSE SAND CLAYEY SLT F i g u r e 41 - E f f e c t o f R e l a t i v e D e n s i t y W i t h D i s t a n c e a t 0, 1, 2, and 3m from C e n t r e l i n e (82 days a f t e r ) 113 p o s i t i o n o f 55% from 0 - 3m (bottom r i g h t graph) . A l s o , t h e t o p o f t h e s i l t l a y e r moves back c l o s e t o i t s o r i g i n a l p o s i t i o n i n s t a g e s from 4m t o 3m. The medium dense sand l a y e r p r o g r e s s i v e l y r e t u r n s t o i t s v i r g i n s t a t e a t 3m from the c e n t r e l i n e . Hence , t h e zone o f i n f l u e n c e from a probe h o l e appears t o be about 2m r a d i u s . 11 .3 .4 C o n c l u s i o n s F o r t h e medium dense sand l a y e r , t h e r e l a t i v e d e n s i t y was i n c r e a s e d from 55% t o 85 - 90%. The r e l a t i v e d e n s i t y p r o f i l e s q u i t e c l e a r l y i n d i c a t e t h e m i x i n g o f t h e sand f i l l w i t h t h e s i l t l a y e r hence i m p r o v i n g t h e t o p 1.5m o f t h e s i l t l a y e r . The r e l a t i v e d e n s i t y i n d i c a t e s t h a t t h e zone o f i n f l u e n c e appears t o be about 2m r a d i u s . 11.4 Shear R e s i s t a n c e 1 1 . 4 . 1 I n t r o d u c t i o n T h e o r i e s c o r r e l a t i n g t h e d r a i n e d r e s i s t a n c e o f sand w i t h cone p e n e t r a t i o n r e s i s t a n c e a r e e i t h e r based on b e a r i n g c a p a c i t y o r on c a v i t y e x p a n s i o n t h e o r y . The c a v i t y e x p a n s i o n approach i s complex i n i t s r e q u i r e m e n t f o r shear s t r e n g t h and c o m p r e s s i b i l i t y i n p u t d a t a f o r i t s a n a l y s i s . The two main parameters which c o n t r o l p e n e t r a t i o n r e s i s t a n c e i n sands a r e s h e a r s t r e n g t h and c o m p r e s s i b i l i t y . S i n c e t h e v a r i a t i o n o f c o m p r e s s i b i l i t y i n most n a t u r a l sands i s s m a l l , t h e shear s t r e n g t h has more i n f l u e n c e on 114 cone r e s i s t a n c e t h a n c o m p r e s s i b i l i t y . F o r t h i s r e a s o n , the b e a r i n g c a p a c i t y t h e o r i e s , which cannot a c c o u n t f o r s o i l c o m p r e s s i b i l i t y a r e a b l e t o o f f e r r e a s o n a b l e p r e d i c t i o n s o f f r i c t i o n a n g l e . From a r e v i e w o f c a l i b r a t i o n chamber and t r i a x i a l t e s t r e s u l t s , R o b e r t s o n and Campane l la (1983) compared t h e v a r i o u s t h e o r e t i c a l r e l a t i o n s h i p s a v a i l a b l e , n o t i n g whether such r e l a t i o n s h i p s t ended t o under o r o v e r e s t i m a t e f r i c t i o n a n g l e . F o l l o w i n g t h i s work, they were a b l e t o propose an average r e l a t i o n s h i p which has been r e d u c e d t o t h e form shown i n F i g u r e 42. A g a i n , the r e l a t i o n s h i p i s a p p l i c a b l e t o m o d e r a t e l y c o m p r e s s i b l e , n o r m a l l y c o n s o l i d a t e d , unaged and uncemented q u a r t z sands . The r e l a t i o n s h i p i s c o n s i d e r e d m e a n i n g f u l f o r t h e sands i n q u e s t i o n and has been used t o e s t i m a t e f r i c t i o n a n g l e s from t h e cone p e n e t r a t i o n t e s t s per formed a t t h e A n n a c i s I s l a n d s i t e . 1 1 . 4 . 2 Time E f f e c t The e f f e c t o f the f r i c t i o n a n g l e as a f u n c t i o n o f t ime i s shown i n F i g u r e 43. The s e r i e s o f graphs show t h e same c h a r a c t e r i s t i c s as t h e r e l a t i v e d e n s i t y g r a p h s , i . e . the sand f i l l m i x i n g w i t h t h e s i l t l e a d i n g t o improvement o f t h e s i l t and a p r o g r e s s i v e i n c r e a s e o f the measured parameter i n the 115 C O N E B E A R I N G . Q C , bars 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 O i 1 1 , , 1 F i g u r e 42 - R e l a t i o n s h i p Between Cone B e a r i n g and F r i c t i o n A n g l e f o r Uncemented and Unaged Q u a r t z Sands A f t e r (Robertson and C a m p a n e l l a , 1983) . DEPTH vs FRICTION ANGLE DEPTH vs FRICTION ANGLE 116 PHI (degrees) 10 20 30 40 SO PHI (degrees) 10 20 30 40 J ! I L SOIL PROFILE SAND SILT UEDIUU DENSE SAND CLAYEY SILT C\ 500+00 (67 DAYS ofter) C\ 500+00 (before vcomp) DEPTH vs FRICTION ANGLE PHI (degrees) 10 20 30 J ! L 40 Ct 500+00 (67 DAYS ofter) Ct 500+00 (before vcomp) Ct 500+00 (82 DAYS after) 50 SOIL PROFILE SANO ru. UEDIUU DENSE SANO CLAYEY SILT Ct 500+00 (82 DAYS after) Ct 500+00 (before vcomp) Q. 500+00 (209 DAYS after) F i g u r e 43 - E f f e c t o f F r i c t i o n A n g l e W i t h Time 67, 82, and 209 Days A f t e r 117 medium dense sand l a y e r , i n t h i s case t h e f r i c t i o n a n g l e . T h i s i s expec ted as an i n c r e a s e i n f r i c t i o n a n g l e c o r r e s p o n d s t o an i n c r e a s e i n t h e r e l a t i v e d e n s i t y . The o O " o f r i c t i o n ang le was i n c r e a s e d from 39 t o 44 - 46 , an i n c r e a s e o f about 6 . A g a i n , t h e peak a t 82 days i s i n e v i d e n c e . As w i t h r e l a t i v e d e n s i t y , no a c c o u n t has been t a k e n o f p o s s i b l e i n c r e a s e s i n l a t e r a l s t r e s s b r o u g h t about by t h e d e n s i f i c a t i o n , so t h e f r i c t i o n a n g l e e v a l u a t e d i s a l s o an upper bound v a l u e . 11 .4 .3 D i s t a n c e E f f e c t The e f f e c t o f the f r i c t i o n a n g l e as a f u n c t i o n o f d i s t a n c e from lm, 2m and 3m from t h e c e n t r e l i n e o f v i b r o c o m p a c t i o n i s shown i n F i g u r e 44. T h i s shows t h e same b e h a v i o u r as r e l a t i v e d e n s i t y w i t h d i s t a n c e , i . e . m i x i n g o f t h e sand f i l l w i t h t h e s i l t and a s t eady d e c r e a s e o f t h e parameter w i t h d i s t a n c e i n t h e medium dense sand l a y e r t o i t s o r i g i n a l p o s i t i o n . 11 .4 .4 C o n c l u s i o n s A c c o r d i n g t o the i n t e r p r e t a t i o n methods a d o p t e d , t h e T r i S t a r probe was c a p a b l e o f i n c r e a s i n g t h e f r i c t i o n a n g l e o f the medium dense sand from 39 t o 44 - 46 . The f r i c t i o n a n g l e p r o f i l e s a r e s i m i l a r t o t h e r e l a t i v e d e n s i t y p r o f i l e s which i s as expec ted as t h e y a r e r e l a t e d t o each o t h e r . CL V Q 1 0 -15-DEPTH vs FRICTION ANGLE PHI (degrees) 10 20 30 -1 1 I 40 i SO DEPTH vs FRICTION ANGLE PHI (degrees) 118 SOIL PROFILE SANO FILL SILT MEDIUU DENSE SAND CLAYEY SILT — Cc 500+00 — C t 500+00 (before vcomp) DEPTH vs FRICTION ANGLE Ct 500+00 C\ 500+00 (before vcomp) 1m SOUTH OF C L 500+00 DEPTH vs FRICTION ANGLE o. V O 1 0 -15 10 I PHI (degrees) 20 30 40 PHI (degrees) 10 20 30 40 J ! I ; L SO SOIL PROFILE SANO n a SILT UEDIUU DENSE SAND CLAYEY SILT - C t 500+00 Ci 500+00 (before vcomp) 2m SOUTH OF C L 500+00 C L 500+00 C L 500+00 (before vcomp) 3m SOUTH OF C L 500+00 F i g u r e 44 - E f f e c t o f F r i c t i o n A n g l e W i t h D i s t a n c e a t 0, 1 ,2 , and 3m From t h e C e n t r e l i n e (82 Days A f t e r ) 119 11 .5 Compar i son o f G e o t e c h n i c a l Parameters 1 1 . 5 . 1 Comparison o f the F r i c t i o n A n g l e E v a l u a t e d from the  DMT and CPTU A p e r c e n t a g e d i f f e r e n c e compar i son o f t h e f r i c t i o n a n g l e e s t i m a t e d b e f o r e and a f t e r by the CPTU and DMT i s shown i n F i g u r e 45. The d a t a r e d u c t i o n programme s u p p l i e d w i t h t h e DMT uses t h e b e a r i n g c a p a c i t y e q u a t i o n o f Durgonog lu and M i t c h e l l (1975) t o c a l c u l a t e f r i c t i o n a n g l e s . As r e g a r d s t h e t ime o f t e s t i n g , t h e 82 day CPTU t e s t was t h e c l o s e s t t o t h e DMT t e s t a t 111 d a y s . The d i f f e r e n c e i n t i m e was no t f e l t t o be i m p o r t a n t as t h e CPTU t e s t i n g has shown t h a t the m a j o r i t y o f t h e t ime e f f e c t had o c c u r r e d by 82 d a y s . The compar i son r e v e a l s t h a t t h e p r o f i l e s a r e s i m i l a r i n shape b u t t h e CPTU g i v e s a p e r c e n t a g e d i f f e r e n c e o f 10% more i n t h e medium dense sand l a y e r w h i l e i t i s a lmost 40% more i n t h e sand f i l l / s i l t zones . T h i s sugges t s t h a t the r e l a t i o n s h i p used t o c a l c u l a t e t h e f r i c t i o n a n g l e from the DMT may need t o be m o d i f i e d t o s u i t t h e s o i l s i n q u e s t i o n s i n c e , u n l i k e t h e CPTU, t h e s i d e f r i c t i o n i s no t measured. Hence t h e CPTU w i l l g i v e a more a c c u r a t e v a l u e o f the f r i c t i o n a n g l e . F u r t h e r , t h e DMT has no t shown t h e same s e n s i t i v i t y t o the changes undergone i n t h e sand f i l l / s i l t l a y e r . 0 DEPTH vs % DIFFERENCE (FRICTION ANGLE) Percentage (%) 10 20 30 40 50 120 SOIL PROFILE From CPT (82 DAYS after). From DMT (111 DAYS after). F i g u r e 45 B e f o r e a n d A f t e r P e r c e n t a g e D i f f e r e n c e C o m p a r i s o n o f F r i c t i o n A n g l e E v a l u a t e d f r o m CPTU and DMT 121 11 .5 .2 Comparison o f Y o u n g / s Modulus E s t i m a t e d From the  DMT and CPTU The Young ' s modulus (E) was e v a l u a t e d from the CPTU soundings u s i n g t h e r e l a t i o n s h i p between cone b e a r i n g and Young' s modulus f o r n o r m a l l y c o n s o l i d a t e d , uncemented sands g i v e n by R o b e r t s o n and C a m p a n e l l a , (1983), which i s shown i n F i g u r e 46. I t i s c o n s i d e r e d t h a t t h e sands encountered a t A n n a c i s I s l a n d a r e a p p l i c a b l e t o the r e l a t i o n s h i p and a 50% f a i l u r e s t r e s s l e v e l has been used as sugges ted by R o b e r t s o n and Campane l la (1983) . F u r t h e r , a v e r t i c a l e f f e c t i v e s t r e s s o f 1 b a r was used based on t h e DMT d a t a . The Young ' s modulus from the DMT was e v a l u a t e d u s i n g a v e r s i o n o f t h e d a t a r e d u c t i o n programme s u p p l i e d w i t h the DMT a p p a r a t u s . I t uses an e m p i r i c a l c o r r e l a t i o n based on M a r c h e t t i (1980) . The compar i son between E from t h e CPTU and DMT i s shown i n F i g u r e 47 f o r t h e medium dense sand o n l y . The d a t a between 0 - 4m i s not shown a i t was t o o v a r i a b l e f o r compar i son p u r p o s e s . F i g u r e 47 shows t h a t t h e Young's Modulus e v a l u a t e d s e p a r a t e l y by t h e CPTU and DMT i s v e r y s i m i l a r f o r t h e s o i l i n q u e s t i o n and t h e a p p l i e d c o n d i t i o n s . The reasons f o r t h e t e s t t i m e s a r e t h e same as g i v e n i n s e c t i o n 1 1 . 5 . 1 . The i n c r e a s e i n E i n the medium dense sand i s s i g n i f i c a n t and i s between 50 - 100%. The above f i n d i n g s suggest t h a t b o t h t h e CPTU and DMT are e q u a l l y e f f e c t i v e i n d e t e r m i n i n g Young' s Modulus f o r t h e 122 100 200 300 400 500 C O N E B E A R I N G . q £ . b a r s F i g u r e 46 R e l a t i o n s h i p Between Cone B e a r i n g and D r a i n e d Young' s Modulus f o r N o r m a l l y C o n s o l i d a t e d , Uncemented Q u a r t z Sands ( A f t e r R o b e r t s o n and C a m p a n e l l a , 1983) - 1 0 0 0 DEPTH vs % DIFFERENCE (Young's Modulus) Percentage (SB) 0 100 2 0 0 3 0 0 4 0 0 123 SOIL PROFILE SAND FILL SILT MEDIUM DENSE SAND CLAYEY SILT E from CPT(82 DAYS after). E D from DMT(111 DAYS after). F i g u r e 47 B e f o r e and A f t e r P e r c e n t a g e D i f f e r e n c e C o m p a r i s o n o f Young's M o d u l u s E v a l u a t e d f r o m CPTU and DMT 124 medium dense sand a t t h i s s i t e , p r o v i d e d t h e same c o n d i t i o n s a r e a p p l i e d . 1 1 . 5 . 3 Comparison o f Shear Modulus E v a l u a t e d From the CPTU  and SCPTU The s h e a r modulus , G M a x , was e v a l u a t e d from the CPTU sound ing u s i n g the r e l a t i o n s h i p between cone b e a r i n g and dynamic s h e a r modulus f o r n o r m a l l y c o n s o l i d a t e d , uncemented q u a r t z sands g i v e n by R o b e r t s o n and Campane l la (1983) shown i n F i g u r e 48. A g a i n , as f o r E , a v e r t i c a l e f f e c t i v e s t r e s s o f 1 b a r was u s e d . The e v a l u a t i o n o f G M a x from t h e SCPTU has a l r e a d y been d i s c u s s e d and can be found i n s e c t i o n 1 0 . 4 . 1 The compar i son shown i n F i g u r e 49, shows t h e b e f o r e and a f t e r p r o f i l e s a t 82 days (when t h e SCPTU was a v a i l a b l e ) o f each p e n e t r a t i o n t e s t . T h i s was done as G M a x g i v e n by t h e SCPTU p r o v i d e d i n c o n c l u s i v e r e s u l t s as d i s c u s s e d i n s e c t i o n 1 0 . 4 . 2 , hence a p e r c e n t a g e d i f f e r e n c e compar i son c o u l d no t be c a r r i e d o u t . As t h e d a t a from 0 - 4m i s m i s s i n g from the SCPTU p l o t o n l y t h e medium dense sand w i l l be d i s c u s s e d . The b e f o r e p r o f i l e s o f each t e s t a r e s i m i l a r , w h i l e t h e CPTU g i v e s a l a r g e r v a l u e f o r G M a x f o r the whole l a y e r . I t has been documented t h a t the SCPTU a c c u r a t e l y d e t e r m i n e s G M a x (Campanel la and R o b e r t s o n , 1986) , t h e r e f o r e i t i s f e l t t h a t t h e r e l a t i o n s h i p which g i v e s a G M a x from t h e CPTU d a t a would r e q u i r e m o d i f y i n g f o r the s o i l s e n c o u n t e r e d . 125 F i g u r e 48 R e l a t i o n s h i p Between Cone B e a r i n g and Dynamic Shear Modulus f o r N o r m a l l y C o n s o l i d a t e d , Uncemented Q u a r t z Sands (Robertson and C a m p a n e l l a , 1986) 5 -a. 10-15-25 I D E P T H v s GUAX (From Seismic CPTU) Gu« (MPa) 50 75 100 125 I 150 126 SOIL PROFILE SAND Flu. SILT MEDIUM DENSE SAND CLAYEY SILT a. o a 10-15-Ct 500+00 (82 D A Y S after) V I R G I N A R E A #1 C L 600+00 (before vcomp) D E P T H v s GMAX (From CPTU) GUAX (MPa) 25 I 50 i_ 75 _1_ 100 125 150 J ' SOIL PROFILE SAND FILL SILT MEDIUM DENSE SAND CLAYEY SILT V I R G I N A R E A #1 C 500+00 (82 D A Y S ofter) F i g u r e 49 Comparison o f G„ E v a l u a t e d from CPTU and SCPTU 127 The CPTU shows an i n c r e a s e o f 50 - 100% i n G M a x a f t e r d e n s i f i c a t i o n . T h i s i s the same as t h e Young' s Modulus a l s o e v a l u a t e d from the CPTU which i s as e x p e c t e d as they a r e r e l a t e d . 1 1 . 5 . 4 Comparison o f L a t e r a l S t r e s s E v a l u a t e d From t h e DMT  and LSCPTU The l a t e r a l s t r e s s was e v a l u a t e d from t h e DMT sounding by c o m b i n i n g K Q and t h e v e r t i c a l e f f e c t i v e s t r e s s , b o t h p r o v i d e d by t h e DMT d a t a r e d u c t i o n programme. The K Q was d e t e r m i n e d by t h e method d e v e l o p e d by M a r c h e t t i (1985) f o r sands from the DMT d a t a which has been shown t o be a good r e l a t i o n s h i p . As r e g a r d s t h e LSCPTU, t h i s gave a d i r e c t measurement o f l a t e r a l s t r e s s which i s no t the t r u e i n - s i t u s t r e s s but a p e n e t r a t i o n l a t e r a l s t r e s s . Hence , LSCPTU t e s t s may p r o v i d e too h i g h a measurement. The DMT and LSCPTU t e s t s were c a r r i e d out a t 111 days and 204 days r e s p e c t i v e l y . The d i f f e r e n c e i n t ime was f e l t t o be n e g l i g i b l e as f o r t h e same r e a s o n g i v e n i n s e c t i o n 1 1 . 5 . 1 . F i g u r e 50 shows t h e b e f o r e and a f t e r p r o f i l e s from the DMT and LSCPTU. T h i s has been done t o h i g h l i g h t t h e l a r g e d i f f e r e n c e i n v a l u e o f l a t e r a l s t r e s s t h a t each has measured due t o d e n s i f i c a t i o n . The DMT d a t a f a l l s i n t o the same range as found by s i m i l a r t e s t i n g c a r r i e d out a t A n n a c i s I s l a n d (Hitchman, 1989) , i . e . an i n c r e a s e i n K Q from 0.5 - 1 .0 , c o r r e s p o n d i n g t o an i n c r e a s e i n l a t e r a l t\ 500+00 (204 DAYS after) VIRGIN AREA #1 DEPTH vs LATERAL STRESS (From DMT) Sigmah (kPa) 0 2 0 0 4 0 0 6 0 0 8 0 0 0-1 1 1 1 L. 1 0 -1 0 0 0 SOIL PROFILE SAND FILL SILT UEOTJM DENSE SAND CLAYEY SILT - C L 500+00 ( 1 1 1 DAYS after) VIRGIN AREA #1 Comparison o f L a t e r a l S t r e s s E v a l u a t e d From t h e DMT and LSCPTU 129 s t r e s s from 75 kPa - 150 k P a . The LSCPTU d a t a has been found t o be too l a r g e (an i n c r e a s e from 400 - 600%) i n compar i son t o t e s t i n g done a t o t h e r s i m i l a r s i t e s . The r e a s o n f o r t h i s was t h a t t h e LSCPTU was s t i l l a t an e x p e r i m e n t a l s t a g e and t h e h i g h v a l u e s ( t a k i n g i n t o account p e n e t r a t i o n ) were due t o equipment and c a l i b r a t i o n p r o b l e m s , i . e . t h e l a t e r a l s t r e s s c e l l gave t o o h i g h a v a l u e p l u s t h e pore p r e s s u r e e lement b e h i n d t h e l a t e r a l s t r e s s c e l l d i d no t f u n c t i o n p r o p e r l y and produced e r r o n e o u s d a t a . T h i s a l s o meant t h a t K Q c o u l d no t be e v a l u a t e d . I n t e r e s t i n g l y though , a p e r c e n t a g e d i f f e r e n c e compar i son ( F i g u r e 51) shows t h a t t h e p r o f i l e s a r e r e l a t i v e l y s i m i l a r . The DMT and LSCPTU show a 50% and 100% d i f f e r e n c e r e s p e c t i v e l y f o r the medium dense sand l a y e r and a g a i n f o r t h e sand f i l l / s i l t l a y e r . A l t h o u g h the LSCPTU a b s o l u t e d a t a i s q u e s t i o n a b l e , t h e LSCPTU has shown i t can measure l a t e r a l s t r e s s b u t t h a t i t r e q u i r e s c a l i b r a t i o n i n o r d e r t o p r o v i d e t h e a c t u a l l a t e r a l s t r e s s which i s a t p r e s e n t b e i n g a d d r e s s e d . Hence , any f u r t h e r compar i sons between l a t e r a l s t r e s s w i l l be based on the DMT d a t a . 1 1 . 5 . 5 Comparison Between L a t e r a l S t r e s s and R e l a t i v e  D e n s i t y One o f t h e o b j e c t i v e s o f t h i s r e s e a r c h was t o i n v e s t i g a t e t h e mechanism o f how the medium dense sand becomes more DEPTH vs % DIFFERENCE (DMT + LSCPTU) Percentage {%) PRO RLE SAND FILL SILT MEDIUM DENSE SAND CLAYEY SILT LS from DMT(111 DAYS after). LS from LSCPTU(204 DAYS after). F i g u r e 51 Percentage D i f f e r e n c e Compar i son o f L a t e r a l S t r e s s E v a l u a t e d From t h e DMT and LSCPTU 131 r e s i s t a n t t o p e n e t r a t i o n and t h e r e f o r e t o l i q u e f a c t i o n . T h i s i s b e l i e v e d t o be caused by t h e r e l a t i v e d e n s i t y , o r l a t e r a l s t r e s s o r a c o m b i n a t i o n o f b o t h , b e i n g i n c r e a s e d . Hence , based on t h e DMT, the l a t e r a l s t r e s s has been i n c r e a s e d by 50% w h i l e based on t h e CPTU, t h e r e l a t i v e d e n s i t y has been i n c r e a s e d by 65%. T h i s sugges t s t h a t the i n c r e a s e i n r e l a t i v e d e n s i t y c o u l d be c o n s i d e r e d the dominant e f f e c t but i t i s f e l t t h e d i f f e r e n c e i s no t l a r g e enough t o be c o n c l u s i v e . T h e r e f o r e , i t i s n e c e s s a r y t o i n v e s t i g a t e how much each parameter c o n t r i b u t e s t o t h e cone b e a r i n g i n c r e a s e . As i t has been shown t h a t t h e K Q c o n d i t i o n and hence l a t e r a l s t r e s s have been i n c r e a s e d due t o d e n s i f i c a t i o n , i t i s p o s s i b l e t o s e p a r a t e t h e i n f l u e n c e s on cone b e a r i n g o f i n c r e a s e d r e l a t i v e d e n s i t y and l a t e r a l s t r e s s . A c c o r d i n g t o t h e r e l a t i o n s h i p o f F i g u r e 39, t h e 75 kPa i n c r e a s e o f h o r i z o n t a l e f f e c t i v e s t r e s s would be r e s p o n s i b l e f o r an o v e r e s t i m a t i o n o f r e l a t i v e d e n s i t y i n t h e r e g i o n o f 15%. On t h i s b a s i s , t h e p o s t - t r e a t m e n t r e l a t i v e d e n s i t i e s shown i n F i g u r e s 40 and 41 s h o u l d be r e d u c e d by 15% o v e r the range o f t r e a t m e n t , w h i l s t the f r i c t i o n a n g l e s o f F i g u r e s 43 and 44 would be reduced by 2 d e g r e e s . T h e r e f o r e , based on t h e f a c t t h a t t h e a b s o l u t e r e l a t i v e d e n s i t y was i n c r e a s e d from 55% t o 90%, t h e r e l a t i v e d e n s i t y c o n t r i b u t e s 20% w h i l e t h e l a t e r a l s t r e s s c o n t r i b u t e s 15% t o the i n c r e a s e i n cone b e a r i n g . A l t h o u g h t h i s i n d i c a t e s the r e l a t i v e d e n s i t y i s s l i g h t l y more dominant i t may be more 132 a p p r o p r i a t e t o suggest t h a t b o t h c o n t r i b u t e e q u a l l y t o the i n c r e a s e i n cone b e a r i n g . 11.6 C o n c l u s i o n s The cone b e a r i n g i n r e l a t i o n t o t i m e showed t h a t f o r t h e t h r e e l a y e r s i n v e s t i g a t e d , i t s g a i n was c u r v e d and peaked between 6 and 82 days a f t e r a s h a r p i n c r e a s e w h i c h was between 200 and 400% f o r the medium dense s a n d . A f t e r 82 d a y s , a d e c r e a s e was no ted which i s f e l t t o be due t o a t i d e change a l t e r i n g t h e ground water l e v e l . The s i l t l a y e r was improved i n d i r e c t l y by t h e sand f i l l m i x i n g w i t h i t from above . In terms o f d i s t a n c e each o f t h e l a y e r s i n d i c a t e d the T r i S t a r probe has a zone o f i n f l u e n c e o f about 2m r a d i u s . The r e l a t i v e d e n s i t y and a n g l e o f f r i c t i o n e x h i b i t e d t h e same b e h a v i o u r , i . e . a p r o g r e s s i v e i n c r e a s e w i t h t i m e . The r e l a t i v e d e n s i t y was i n c r e a s e d from 55% t o 85 - 90% w h i l e o o o the a n g l e o f f r i c t i o n was i n c r e a s e d from 39 t o 44 - 46 . Both parameters a l s o i n d i c a t e d t h e m i x i n g e f f e c t o f t h e sand f i l l / s i l t l a y e r s q u i t e c l e a r l y . The Young's modulus e v a l u a t e d from the DMT and CPTU b o t h i n d i c a t e d a s i m i l a r i n c r e a s e o f 50 - 100% from b e f o r e and a f t e r v i b r o c o m p a c t i o n i n t h e medium dense s a n d . Hence , b o t h t h e CPTU and DMT may be used t o e v a l u a t e Y o u n g ' s Modulus f o r the medium dense sand a t t h i s s i t e p r o v i d i n g the a p p l i e d c o n d i t i o n s a r e t h e same. 133 The CPTU i n compar i son t o t h e SCPTU gave a l a r g e r G M a x f o r t h e b e f o r e p r o f i l e . As i t has been documented t h a t the SCPTU a c c u r a t e l y de termines G M a x (Campanel la and R o b e r t s o n , 1986) , i t i s f e l t t h a t t h e r e l a t i o n s h i p used t o d e v e l o p G Max f r o m t ^ i e C P T U d a t a would r e q u i r e m o d i f i c a t i o n f o r the s o i l s e n c o u n t e r e d . The CPTU G M a x i n d i c a t e d an i n c r e a s e o f 50 - 100% from b e f o r e and a f t e r v i b r o c o m p a c t i o n which i s e q u a l t o the i n c r e a s e i n Young's modulus which i s as e x p e c t e d as they a r e r e l a t e d . The compar i son between t h e DMT t h e LSCPTU l a t e r a l s t r e s s showed a s i m i l a r p r o f i l e b u t the LSCPTU was 50% g r e a t e r i n t h e medium dense sand and sand f i l l / s i l t l a y e r . T h i s sugges t s t h a t t h e LSCPTU needs f u r t h e r c a l i b r a t i o n which a t p r e s e n t i s b e i n g a d d r e s s e d . I t i s f e l t t h a t t h e i n c r e a s e i n cone b e a r i n g i s due e q u a l l y t o an i n c r e a s e i n l a t e r a l s t r e s s and r e l a t i v e d e n s i t y as b o t h i n c r e a s e s a r e r e l a t i v e l y c l o s e . 134 12.0 COMPARISON WITH OTHER VIBROCOMPACTION SYSTEMS 12.1 I n t r o d u c t i o n The compact ion c a p a c i t y and b e h a v i o u r o f t h e T r i S t a r probe have been demonstrated i n t h e p r e c e d i n g s e c t i o n s . To p r o p e r l y a s s e s s t h e b e n e f i t s o f t h e i n s t r u m e n t i t has t o be compared r e l a t i v e t o o t h e r v i b r o c o m p a c t i o n equipment a v a i l a b l e . T h i s has been c a r r i e d out based on work done by Hitchman (1989) which uses two methods. The f i r s t compares t h e a b i l i t y o f the T r i S t a r and o t h e r probes t o d e n s i f y s o i l around a s i n g l e compact ion p r o b e . The second method i n v o l v e s comparing the g r i d s p a c i n g / p r o b e d i a m e t e r r a t i o o f each o f t h e p r o b e s . 12.2 D e n s i f i c a t i o n Comparison I n F i g u r e 52, the d a t a o f t h r e e o t h e r a u t h o r s has been compared w i t h t h e T r i S t a r d a t a . On t h e o r d i n a t e i s p l o t t e d t h e p r e v i o u s l y adopted q u a n t i t y , t h e f i n a l cone b e a r i n g n o r m a l i z e d f o r t h e i n i t i a l cone b e a r i n g m u l t i p l i e d by t h e i n i t i a l r e l a t i v e d e n s i t y . In t h i s way, d i f f e r e n c e s i n compact ion depths and i n i t i a l d e n s i t i e s may be taken i n t o c o n s i d e r a t i o n . On t h e a b s c i s s a i s p l o t t e d the d i s t a n c e from the p r o b e , n o r m a l i z e d by t h e d i a m e t e r o f the p r o b e . T h i s i s i m p o r t a n t s i n c e t h e e f f e c t i v e s i z e s o f p r o b e s c o n s i d e r e d d i f f e r by n e a r l y an o r d e r o f magni tude . W h i l s t t h e s i z e o f t h e equipment i s t a k e n i n t o c o n s i d e r a t i o n , t h e r e i s no a l l o w a n c e f o r d i f f e r e n c e s o f machine power o u t p u t . Comparing s i m i l a r mach ines , the (Jl Ld O > 1 L J a: < x o z LJ O O a M < 135 o 1 1 1 1 1 1 r 2 4 6 8 10 DISTANCE FROM PROBE / DIAMETER OF PROBE F i g u r e 52 A b i l i t y o f t h e T r i S t a r Probe t o D e n s i f y S o i l Around a S i n g l e Compact ion Probe Compared t o O t h e r Probes ( A f t e r H i t c h m a n , 1989) 136 v i b r o f l o t o f D ' A p p o l o n i a (1953) f o r which d a t a i s shown i n F i g u r e 52, d e v e l o p e d a c e n t r i f u g a l f o r c e o f 10 t o n s , compared t o o n l y 2.3 tons f o r the Phoenix equipment . No such d a t a i s a v a i l a b l e f o r the machine d e s c r i b e d by Webb and H a l l (1969), b u t i t i s assumed t o be o f a t l e a s t t h e c a p a c i t y as t h a t o f D ' A p p o l o n i a . The v i b r a t o r a top t h e T r i S t a r probe d e v e l o p e d a c e n t r i f u g a l f o r c e o f up t o 1.13 MN (Massasch and V a n n e s t e , 1988) . F i g u r e 52 shows t h a t each o f t h e p r o b e s except the Phoenix probe a r e a b l e t o cause s o i l improvement a t up t o d i s t a n c e s e q u a l t o about 2 probe d i a m e t e r s , whereas t h e Phoenix probe i s c a p a b l e o f i m p r o v i n g s o i l a t d i s t a n c e s o f up t o 6 o r more probe d i a m e t e r s when d r a i n a g e i s u s e d . I f d r a i n a g e i s no t u s e d , t h e r e s u l t s a r e w i t h i n the range o f s i m i l a r equipment , except i n t h e v i c i n i t y o f t h e probe where p o o r e r r e s u l t s were o b t a i n e d . However, t h e T r i S t a r and D ' A p p o l o n i a probes a r e more e f f e c t i v e up t o 2 probe d i a m e t e r s . 12.3 G r i d S p a c i n g / P r o b e Diameter Compar i son T a b l e 10 shows d e t a i l s o f t h e major systems a v a i l a b l e f o r t h e deep compact ion o f s o i l s i n - s i t u . To compare a p p r o x i m a t e l y the e f f e c t i v e n e s s o f t h e v a r i o u s machines , t h e r a t i o o f t y p i c a l probe s p a c i n g t o probe d i a m e t e r has been c o n s i d e r e d . T y p i c a l v a l u e s o f t h i s parameter f o r the T r i S t a r and s i m i l a r v e r t i c a l l y v i b r a t i n g systems a r e i n t h e range o f 1 t o 3, w h i l e the v i b r o f l o t a t t a i n s v a l u e s 137 Machine Diameter Frequency S p a c i n g D (m) (Hz) S (m) S / D r a t i o Reference GKN V i b r o f l o t 0.45 30 2.7-3.7 6-8 Brown 1977 F o s t e r T e r r a p r o b e 0.76 15 0.9-2.4 1-3 Anderson 1974 V i b r o r o d 0.5 - 1.7 3 S a i t o , 1977 K y t i l u s 2.1 25 6.5 y Davis e t a l . , 1981 V i b r o - w i n g 1.6 20 2.5 2 M a s s a r s c h & Broms,1983 F r a n k i T r i s t a r 1.0 20 2.0 2 Massarsch & Vannes te ,1988 Phoenix Machine 0.19 25 1.8 9 P r e s e n t s t u d y T a b l e 10 D e t a i l s o f V a r i o u s V i b r o c o m p a c t i o n Systems ( A f t e r Hi tchman, 1989) 138 from 6 t o 8. T h i s r e f l e c t s w e l l t h e w i d e l y h e l d b e l i e f t h a t t h e h o r i z o n t a l l y v i b r a t i n g d e v i c e s a r e f a r more e f f e c t i v e t h a n t h e v e r t i c a l l y v i b r a t i n g p r o b e s . The Phoenix Machine s c o r e s t h e h i g h e s t s p a c i n g t o d i a m e t e r r a t i o o f 9. T h i s i n d i c a t e s t h a t f o r i t s s i z e , t h e Phoenix Machine may be c o n s i d e r e d t h e most e f f e c t i v e o f t h e systems c o n s i d e r e d . 12.4 H i i T i v m a T - Y The f i r s t compar i son i n d i c a t e d t h a t the T r i S t a r probe i s e q u a l t o s i m i l a r probes i n i t s a b i l i t y t o d e n s i f y up t o 2 probe d i a m e t e r s away. However, t h e Phoenix P r o b e , when d r a i n a g e i s u s e d , appears t o be more e f f e c t i v e beyond 2 probe d i a m e t e r s . T h e r e a f t e r , t h e second compar i son showed t h a t t h e T r i S t a r probe i s e q u a l l y e f f e c t i v e as t o s i m i l a r systems b u t t h e Phoenix probe appears t o be t h e most e f f e c t i v e o v e r a l l . 139 13.0 CONCLUSIONS 13 .1 I n t r o d u c t i o n The p r i m a r y o b j e c t i v e s o f t h i s r e s e a r c h were t h e l o n g t erm e v a l u a t i o n o f t h e per formance o f t h e T r i S t a r v i b r o c o m p a c t i o n t e c h n i q u e and t o compare v a r i o u s p e n e t r a t i o n t e s t i n g equipment . T h i s was a c o n t i n u a t i o n o f t h e work c a r r i e d out by t h e c o n t r a c t o r , F r a n k i Canada L t d . 13.2 P o s t C o n s t r u c t i o n C o n c l u s i o n s I t was c o n c l u d e d t h a t t h e 750 f e e t l o n g by 15 f e e t wide s t r i p a r e a was s u c c e s s f u l l y d e n s i f i e d by t h e T r i S t a r method down t o a depth o f 10m. D e n s i f i c a t i o n i n t h e medium dense sand l a y e r (below 5m) exceeded d e s i g n c r i t e r i a , as v e r i f i e d by e x t e n s i v e SPT and CPTU t e s t s . The i n i t i a l SPT b lowcount v a r i e d between 8 and .16 and t h e r e q u i r e d minimum had t o exceed 17 a t t h e 10m d e p t h . The a c t u a l average b lowcount a f t e r t r e a t m e n t v a r i e d between 40 and 65 a l t h o u g h maximum blowcount v a l u e s o f 81 were a c h i e v e d . No d e n s i f i c a t i o n was expec ted i n t h e s i l t l a y e r , but CPTU t e s t s showed t h a t an improvement o c c u r r e d i n d i r e c t l y by m i x i n g o f t h e s i l t w i t h t h e sand f i l l above . T h u s , i t was c o n c l u d e d t h a t the o b t a i n e d d e n s i f i c a t i o n i n d i c a t e d t h a t t h e adopted compact ion p r o c e d u r e ( v i b r a t i o n t i m e and g r i d s p a c i n g ) was c o n s e r v a t i v e . 140 13.3 CPTU R e s u l t s In terms o f the l o n g term e f f e c t s , t h e CPTU was the p r i m a r y s o u r c e o f i n f o r m a t i o n . I t was used t o i n v e s t i g a t e t h e t i m e and d i s t a n c e b e h a v i o u r o f t h e s o i l . The r e s u l t s f o r each l a y e r i n v e s t i g a t e d , showed an i n c r e a s e i n cone b e a r i n g w i t h t ime t o peak between 6 and 82 d a y s . A f t e r 82 d a y s , a d e c r e a s e i s e v i d e n t which i s f e l t t o be due t o ground water l e v e l changes caused by t i d e l e v e l d i f f e r e n c e s . The g a i n i s between 200% and 400%. The e f f e c t o f d i s t a n c e shows t h a t f o r each o f t h e 3 l a y e r s t h e T r i S t a r probe has a zone o f i n f l u e n c e o f about 2m r a d i u s . Through t h e i n v e s t i g a t i o n i t has been shown t h a t t h e s i l t l a y e r , a m a t e r i a l not s u i t a b l e f o r v i b r o c o m p a c t i o n has i n f a c t been improved . The p r o c e s s was an i n d i r e c t r e s u l t o f v i b r o c o m p a c t i o n as the sand f i l l above t h e s i l t mixed w i t h t h e s i l t and caused t h e t o p 1.5m o f t h e 2.5m s i l t l a y e r t o be i m p r o v e d . The f r i c t i o n r a t i o p r o v e d t o be a good s o i l t y p e i n d i c a t o r . 13.4 DMT R e s u l t s The DMT r e s u l t s were o n l y c a r r i e d out a t one p o i n t i n t ime but were comparable t o those o f the CPTU. By c a r r y i n g out DMT t e s t s p e r p e n d i c u l a r t o each o t h e r , i t was found t h a t t h e T r i S t a r probe d e n s i t i e s e q u a l l y i n t h e h o r i z o n t a l d i r e c t i o n . L i k e t h e f r i c t i o n r a t i o , t h e M a t e r i a l Index p r o v e d t o be a good s o i l t y p e i n d i c a t o r . 141 13.5 SCPTU R e s u l t s The SCPTU d i d not p r o v i d e good d a t a from t h i s s i t e due t o equipment and o p e r a t i o n a l p r o b l e m s , hence no c o n c l u s i o n s c o u l d be made. 13.6 LSCPTU R e s u l t s T h i s i n s t r u m e n t c o n f i r m e d t h e way i n which t h e s o i l responded t o v i b r o c o m p a c t i o n b u t o n l y q u a l i t a t i v e l y . T h i s was because the d a t a was e r r o n e o u s due t o the i n s t r u m e n t s t i l l b e i n g i n t h e e x p e r i m e n t a l s t a g e . 13.7 I n t e r p r e t a t i o n o f G e o t e c h n i c a l Parameters The r e l a t i v e d e n s i t y and f r i c t i o n a n g l e showed s i m i l a r b e h a v i o u r , i . e . a p r o g r e s s i v e i n c r e a s e w i t h t i m e . The r e l a t i v e d e n s i t y was i n c r e a s e d , f r o m 55% t o 85 - 90% w h i l e o o o t h e f r i c t i o n a n g l e was i n c r e a s e d from 39 t o 44 - 46 . The compar i son between Y o u n g ' s modulus e v a l u a t e d from t h e DMT and CPTU was q u i t e f a v o u r a b l e i n t h e medium dense sand l a y e r , b o t h t e s t s i n d i c a t i n g an i n c r e a s e o f 50 - 100%. T h i s sugges t s t h a t the CPTU and DMT a r e e q u a l l y e f f e c t i v e i n d e t e r m i n i n g Young's Modulus f o r t h e medium dense sand a t t h i s s i t e and the a p p l i e d c o n d i t i o n s . A s i m i l a r i n c r e a s e (50 - 100%) was noted f o r G M a x e v a l u a t e d from t h e CPTU which was as expected as t h e two a r e r e l a t e d . On compar i son t o the b e f o r e p r o f i l e s o f t h e SCPTU (as t h e a f t e r were erroneous) the CPTU v a l u e s were g r e a t e r which 142 sugges ted t h a t t h e r e l a t i o n s h i p would need t o be m o d i f i e d t o s u i t t h e s o i l s e n c o u n t e r e d . W i t h r e g a r d t o l a t e r a l s t r e s s , t h e LSCPTU and DMT p r o d u c e d a v e r y s i m i l a r p e r c e n t a g e d i f f e r e n c e p r o f i l e a l t h o u g h the LSCPTU p r o v i d e d a 50% g r e a t e r d i f f e r e n c e . T h i s s u g g e s t s , t h a t the LSCPTU needs f u r t h e r c a l i b r a t i o n i n o r d e r t o p r o v i d e a more a c c u r a t e v a l u e o f t h e l a t e r a l s t r e s s , wh ich a t p r e s e n t i s b e i n g a d d r e s s e d . Hence , the DMT d a t a was used t o as ses how l a t e r a l s t r e s s and r e l a t i v e d e n s i t y c o n t r i b u t e t o the i n c r e a s e i n cone b e a r i n g due t o d e n s i f i c a t i o n . T h i s i n d i c a t e d t h a t t h e l a t e r a l s t r e s s and r e l a t i v e d e n s i t y c o n t r i b u t e 15% and 20% r e s p e c t i v e l y . The s m a l l d i f f e r e n c e i s f e l t t o suggest t h e y c o n t r i b u t e e q u a l l y t o t h e i n c r e a s e i n cone b e a r i n g . 13.8 Comparison t o O t h e r Probes The T r i S t a r probe compares w e l l w i t h o t h e r such equipment . However, i t has been shown t h a t when d r a i n a g e i s u sed as i n t h e case o f t h e Phoenix p r o b e , the v i b r o c o m p a c t i o n e f f e c t i s g r e a t e r beyond t h e e f f e c t i v e n e s s o f t h e T r i S t a r p r o b e . 13.9 Recommendations F o r F u t u r e R e s e a r c h The o p e r a t i o n o f t h e T r i S t a r probe worked v e r y w e l l a t t h i s p a r t i c u l a r s i t e as i t exceeded t h e r e q u i r e d d e n s i f i c a t i o n c r i t e r i a . T h e r e f o r e no recommendations are n e c e s s a r y i n t h i s r e g a r d . 143 F u t u r e r e s e a r c h s h o u l d focus on p r o v i d i n g a comprehens ive t i m e s t u d y o f t h e v i b r o c o m p a c t e d m a t e r i a l . I t i s sugges ted t h a t t h i s be done on a weekly b a s i s . A l s o , i n s t e a d o f u s i n g o n l y t h e CPTU on a r e g u l a r b a s i s , t h e SCPTU, DMT and LSCPTU s h o u l d be used as w e l l . 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INTERPRETED et (bar) (bar) Rf CD U (a. of ratar) RATIO AU/Ot PROFILE a L O *) 0 E a. ui a Oapth Inoramant i .025 m Mox Oapth i 14. 85 a 171 U B C I N S I T U T E S T I N G S i t o Location* ANNACIS IS VCOMP CPT Data i On Si to Loot C8B-ANN-10 Cona Uaadi 18/03/88 UBC7 BTIP & BPS Poga Noi C o m i n t t i 1 / 2 VIRGIN AREA 300 CONE BEARING Ct Our) SLEEVE FRICTION (bar) o L O a E X t~ 0_ UJ Q FRICTION RATIO PORE PRESSURE DIFFERENTIAL P.P. INTERPRETED Rf CD U te. of ratar) RATIO AU/Ot PROFILE 0 SO -.2 Q .9 0| * ' * * I 01 Dapth Incromont • . 029 n Max Dapth • 15.075 m Ul U B C I N S I T U T E S T I M G SI to Location! ANNACIS IS VCOMP CPT Data • On SI to Loci C88-ANN-11 Cona Uoodi 18/05/88 UBC7 BTIP & BFS Pago Not 1 / 1 Commantoi CL SECTION A COC BEARING SLEEVE FRICTION Ot (bar) (bar) 0 250 0 01 I 0-a t a •P 9 E X r-Q. LU a FRICTION RATIO PORE PRESSURE DIFFERENTIAL P.P. INTERPRETED RF OD U fa. of isUr) RATIO AU/Ot PROFILE 50 -.2 0 10 15-• 5 10 15* Depth Increment i .025 m Max Dopth i 11.1 • U B C I M S I T U T E S " F I M G S l t a Location. ANNACIS IS VCOMP CPT Data i 02/06/88 Paga Noi 1 / 1 On S l t a Loci C88-ANN -12 Cona Uaadi UBC7 BTIP & 8FS Commantsi 1H<S) SECTION A CONE BEARING SLEEVE FRICTION FRICTION RATIO PORE PRESSURE DIFFERENTIAL P.P. INTERPRtTUJ 0t (bar) (bar) Rf CO U Ob of *atar> RATIO AUTOt PROFILE Oapth Incrowont • . 02S m Max Oapth • 10.82S m U B C I M S I T U T E S * T I N G Stta Location! ANNACIS IS VCOMP CPT Data • 02/08/88 Page Not 1 / 1 On S i t s Loci C88-ANN -13 Cona Usadi UBC7 BTIP * BPS Commentei 2M<S> SECTION A L a o E 0. LU a CONE BEARING Ot (bar) SLEEVE FRICTION (bar) 250 0 o FRICTION RATIO Rf (X) PORE PRESSURE U Oh of «ct«r) 0 SO DIFFERENTIAL P.P. RATIO AU/Ot -.2 0 .0 O - - -INTERPRETED PROFILE • 10 IS 10 15 Depth Increment i . 02S m Max Depth i 10. 83 m H Ol U B C I M S I T U T E S ' r i M G S i t s Loeattom ANNACIS IS VCOMP CPT Data • 02/00/88 Paga Noi 1 / 1 On S l t a Loci C88-ANN -14 Cona Uaadi UBC7 BTIP & BPS Commantai 3M<S> SECTION A CONE BEARING Dt Qxr) SLEEVE FRICTION (bar) L a +> a E X r— a. LU • FRICTION RATIO Rf (I) 0 S 10 15 Dapth Incranant i .025 m PORE PRESSURE U (a. of raUr) 0 50 •T 10 IS s DIFFERENTIAL P.P. RATIO AU/Ot -.2 0 INTERPRETED PROFILE 10 IS • S 10 IS Max Dapth i 11.85 • H Ul tn DEPTH < m o t a r s ) U B C I M S I T U T E S T I M G S l t a Looatloni ANNACIS IS VCOMP On S l t a Loot C8B-ANN-20 CPT Data i 23/0B/B8 Cona Uaodt UBC7 BTIP & BFS Paga Not 1 / 1 Conunantat CL SECTION A «r> (I) L 0) +> CP E 0. UJ a CONE BEARING Ot (bar) SLEEVE FRICTION (bar) 250 0 FRICTION RATIO PORE PRESSURE DIFFERENTIAL P.P. INTERPRETED Rf CD U (fc of *atir> RATIO AU/Ot PROFILE 0 5 0 SO -.2 0 Dapth Incraaant • .025 m Max Dapth t 11.0 m 158 DMT D A T A Location : ANNACIS IS VIBROCOMP Filename : D8-AN-1 Test Dote: 6-6-88 Po I Pi ; Sv' Thrust (kg) 0 20 40 0 200040006000 0.1 Location : ANNACIS IS VIBROCOMP Filename : D8-AN-2 Test Date: 15-6-88 U.B.C. In Situ Testing 

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