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An evaluation of the Phoenix machine : a new apparatus for the in situ densification of soil Hitchman, Ross 1989

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AN EVALUATION OF THE PHOENIX MACHINE A NEW APPARATUS FOR THE IN SITU DENSIFICATION OF SOIL by ROSS HITCHMAN BSc, Portsmouth P o l y t e c h n i c , 1979 A THESIS SUBMITTED IN PARTIAL FULFILMENT THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF CIVIL ENGINEERING We accept t h i s t h e s i s as conforming t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1989 © Ross Hitchman, 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. (Signature) Ross Hitchman Department of C i v i l Engineering The University of British Columbia Vancouver, Canada Date A p r i l 28 , 1989 DE-6 (2/88) i i ABSTRACT An i n s i t u d e n s i f i c a t i o n probe which employs the novel technique of simultaneous v i b r a t i o n and drainage has been developed by Phoenix E n g i n e e r i n g f o r the purpose of i n s i t u improvement of lo o s e , g r a n u l a r s o i l s . I t i s b e l i e v e d t h a t pumping of water d u r i n g the d e n s i f i c a t i o n process o f f e r s improved d e n s i f i c a t i o n c a p a b i l i t y over systems o p e r a t i n g with v i b r a t i o n alone. T h i s study e v a l u a t e s the performance of the Phoenix system and i n v e s t i g a t e s some o f the parameters which i n f l u e n c e the e f f e c t i v e n e s s of the d e n s i f i c a t i o n p r o c e s s . A t e s t i n g programme was conducted a t a s i t e i n the Lower Mainland t o assess the instrument. The s i t e c o n s i s t s of a pumped f i l l o v e r l y i n g a n a t u r a l medium sand. F i e l d t e s t s were accomplished i n both m a t e r i a l s . C h a r a c t e r i z a t i o n of the s i t e and treatment e v a l u a t i o n were achieved by u s i n g i n s i t u t e s t s . Changes t o s o i l parameters due t o d e n s i f i c a t i o n treatment were examined, t a k i n g i n t o account the m o d i f i c a t i o n of s t r e s s e s brought about by the vibrocompaction process. I t was found t h a t r e l a t i v e d e n s i t i e s up t o 85-90% c o u l d c o n s i s t a n t l y be achieved. The study h i g h l i g h t e d the important c o n t r i b u t i o n of pumping water from the s o i l d u r i n g compaction o p e r a t i o n s . I t demonstrated t h a t the Phoenix system can o f f e r improved compaction over a l t e r n a t i v e commercial compaction systems i f probe s i z e and spacing are taken i n t o account. The importance of m a i n t a i n i n g an adequate supply o f b a c k f i l l i s emphasized. I t was found t h a t the machine was w e l l s u i t e d t o compacting s i l t y sands, both n a t u r a l and f i l l , but was unable t o cause improvement i n s i l t . The i n f l u e n c e s of changing probe spacing and p a t t e r n were examined. The e f f e c t s of time spent d e n s i f y i n g and changes t o s o i l c o n d i t i o n s due t o time e f f e c t s are b r i e f l y covered. F i n a l l y , the l i m i t a t i o n s of t h i s study are noted, and recommendations f o r f u t u r e r e s e a r c h are proposed. A d v i s o r : Dr. R i c h a r d G. Campanella CONTENTS Page Abs t r a c t i i L i s t of Tables v L i s t of Fi g u r e s v i Acknowledgements i x Chapter 1. INTRODUCTION . 1 1.1 O b j e c t i v e s of Present Research 1 1.2 Scope 3 Chapter 2. REVIEW OF VIBROCOMPACTION 6 2.1 Vibrocompaction Procedure 6 2.2 A l t e r n a t i v e Techniques of Vibrocompaction 8 2.3 Mechanism of Vibrocompaction 10 2.4 Parameters A f f e c t i n g Vibrocompaction 12 2.5 Compaction C o n t r o l 16 2.6 Development of Phoenix Concept 18 2.7 Summary ...18 Chapter 3. RESEARCH SITE 20 3.1 Regional Geology 20 3.2 S i t e D e s c r i p t i o n 21 Chapter 4. EQUIPMENT AND PROCEDURES 2 7 4.1 The Phoenix D e n s i f i c a t i o n Equipment 27 4.2 In S i t u T e s t s . . . . 3 2 4.2.1 T e s t i n g V e h i c l e 32 4.2.2 Tes t s Performed 33 4.2.3 Piezocone Penetration T e s t (CPTU)... 33 4.2.4 F l a t Dilatometer P e n e t r a t i o n T e s t (DMT)...35 4.2.5 Seismic Piezocone P e n e t r a t i o n T e s t (SCPTU)37 4.3 Scope of F i e l d T r i a l Programme 38 Chapter 5. INTERPRETATION AND IMPROVEMENT OF SOIL PARAMETERS FROM IN SITU TESTS 45 5.1 S o i l P r o f i l e 46 5.2 R e l a t i v e Density 59 5.3 Shear Resistance 64 5.4 Modulus and C o m p r e s s i b i l i t y . . 70 5.4.1 Constrained Modulus 71 5.4.2 Shear Modulus 7 3 5.5 In S i t u S t r e s s Conditions 76 5. 6 Summary 82 iv CONTENTS (continued) Page Chapter 6. TEST RESULTS 83 6.1 Evaluation of Single Compaction Probe 83 6.2 Investigation of Variable Parameters 88 6.2.1 Effe c t of Spacing and Pattern 88 6.2.2 Influence of Frequency 93 6.2.3 Ef f e c t of Time Spent Densifying 94 6.2.4 Effe c t of Time Following Densification....96 6.3 Influence of Simultaneous Drainage ..99 6.4 Ground Vibration Monitoring 101 6.5 Comparison with Other Vibrocompaction Systems..103 6.6 Summary 107 Chapter 7. SUMMARY AND CONCLUSIONS 109 7.1 Equipment and Procedures 109 7.2 Performance 110 7.3 Recommendations I l l References 113 Appendix - F i e l d Test Data 117 V LIST OF TABLES Page Table I Details of Penetration Tests Performed 41 Table II Details of Phoenix Densification Probes 4 3 Table III Details of Various Vibrocompaction Systems... 106 v i LIST OF FIGURES Page Figure 1 Range of S o i l Types Suitable for Improvement by Vibrocompaction (after Brown, 1977) 14 Figure 2 Map of Lower Mainland Area Showing Location of Research Site 22 Figure 3 Plan of Annacis North Pier Research Site Showing Locations of Test Areas 23 Figure 4 P a r t i c l e Size D i s t r i b u t i o n Curves f o r F i l l Sand and Fraser River Sand 26 Figure 5 Schematic of Phoenix Densification Probe 29 Figure 6 Plan of Research S i t e Showing Locations of F i e l d Test Series 39 Figure 7 Plan Showing Layout of Phoenix Probes and Penetration Tests Performed 4 0 Figure 8 S o i l Behaviour Type C l a s s i f i c a t i o n Chart (after Robertson, 1985) 47 Figure 9 Cone Penetrometer P r o f i l e ANP1 Showing Interpreted S o i l P r o f i l e 48 Figure 10 Cone Penetrometer P r o f i l e ANP9 Showing Interpreted S o i l P r o f i l e 49 Figure 11 Section Through Research S i t e Showing S o i l Layers 52 Figure 12 Comparison of Cone Penetrometer Soundings Performed i n Hydraulically Placed F i l l Sand Before and After Treatment with Phoenix Densification Equipment 53 Figure 13 Comparison of Cone Penetrometer Soundings Performed i n Natural Fraser River Sands Before and After Treatment with Phoenix Densification Equipment 54 Figure 14 F l a t Dilatometer P r o f i l e ANPDl Before Treatment With Phoenix Densification Equipment 57 Figure 15 F l a t Dilatometer P r o f i l e ANPD2 After Treatment With Phoenix Densification Equipment 58 v i i LIST OF FIGURES (continued) Page Figure 16 Relative Density Relationship for Uncemented and Unaged Quartz Sands (Adapted from Baldi et a l . 1982) 60 Figure 17 Comparison of Relative Densities From CPT Before and After Treatment with Phoenix Densification Equipment for Hydraulically Placed F i l l Sand 61 Figure 18 Comparison of Relative Densities From CPT Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands 63 Figure 19 Relationship Between Cone Bearing and F r i c t i o n Angle for Uncemented and Unaged Quartz Sands (After Robertson and Campanella, 1983) 65 Figure 20 Comparison of F r i c t i o n Angles From CPT Before and After Treatment with Phoenix Densification Equipment for Hydraulically Placed F i l l Sand 67 Figure 21 Comparison of F r i c t i o n Angles From CPT Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands 68 Figure 22 Comparison of F r i c t i o n Angles From DMT Before and After Treatment with Phoenix Densification Equipment f o r Fraser River Sands 69 Figure 23 Comparison of Constrained Modulus From DMT Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands » 72 Figure 24 Comparison of Maximum Shear Modulus From SCPT Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands 75 Figure 25 Relationship Between Cone Bearing and F r i c t i o n Sleeve Before and After Treatment With Phoenix Densif i c a t i o n Equipment 78 v i i i LIST OF FIGURES (continued) Page Figure 26 Comparison of K Q From DMT Before and After Treatment With Phoenix Densification Equipment 79 Figure 27 Comparison of In Situ Horizontal Stress From DMT Before and After Treatment With Phoenix Densification Equipment 81 Figure 28 Variation i n Normalized Cone Resistance Around a Single Phoenix Probe Hole 85 Figure 29 Proposed Relationship to Enable the Determination of Variation of F i n a l Cone Bearing with Distance from Phoenix Probe Hole 87 Figure 30 Influence of Spacing of Phoenix Machine Probes on Cone Resistance for Fraser River Sand 89 Figure 31 Influence of Pattern of Phoenix Machine Probes on Cone Resistance f o r Fraser River Sand 90 Figure 32 Influence of Spacing of Phoenix Machine Probes on Cone Resistance for Hydraulically Placed F i l l Sand 92 Figure 33 Influence of Time Spent Densifying on Cone Resistance for Fraser River Sand 95 Figure 34 Influence of Time Following Densification on Cone Resistance for Fraser River Sand 98 Figure 35 Influence of Drainage Element on Cone Resistance for Fraser River Sand 100 Figure 36 Comparison of A b i l i t y of Phoenix Machine to Densify S o i l Around a Single Compaction Probe with Other Equipment 104 i x Acknowledgements I wish to express gratitude to my supervisor, Professor R.G. Campanella, for the coordination of t h i s topic as a research project, and for his advice and encouragement throughout the work. I would l i k e thank my fellow students of the i n s i t u t e s t i n g group who generously devoted t h e i r time to a s s i s t with carrying out the f i e l d t e s t s . Special thanks are due to J.P. Sully for his interest and suggestions throughout the work. Also to the technical support s t a f f of the Department of C i v i l Engineering, for the preparation and maintenance of the i n s i t u equipment. I extend my appreciation to B.C. Highways for making the area adjacent to the Alex Fraser Bridge accessible for t h i s research. I am grateful for the f i n a n c i a l support of the Natural Sciences and Engineering Research Council of Canada (Grant 5-83401), paid through a Department of C i v i l Engineering Graduate Research Assistantship. To my wife, C l a i r e , my warmest thanks for her understanding, support and companionship throughout the duration of t h i s study. I would l i k e p a r t i c u l a r l y to express my appreciation to to W.E.Hodge of Phoenix Engineering Ltd.. F i r s t l y for the opportunity to be involved with the novel research concept of the Phoenix Machine and secondly f o r the pleasure of working together. I t was h i s constant enthusiasm, support and encouragement which enabled t h i s project to reach completion. 1 1. INTRODUCTION 1.1 O b j e c t i v e s of Present Research The poor engineering c h a r a c t e r i s t i c s of loose sands have long been recognized, and are t y p i c a l l y expressed as inadequate l o a d bearing c a p a c i t y , l e a d i n g t o e x c e s s i v e settlements. Under v i b r a t o r y loading such as t h a t induced by earthquakes, r a i l r o a d s and machine foundations, settlements may be l a r g e and sudden. In terms of c o n s t r u c t i o n approach, the a l t e r n a t i v e s have been to found p i l e s on deeper, more competent s t r a t a , or t o compact the troublesome s o i l s t o a higher d e n s i t y . The compaction of s o i l s i n s i t u i s now used r o u t i n e l y t o overcome d i f f i c u l t foundation problems caused by loose g r a n u l a r m a t e r i a l s , and has found a p p l i c a t i o n on many recent and major p r o j e c t s (eg. Solymar e t al.,1984; Hussin and A l i , 1987). The technique of d e n s i f y i n g s o i l w i t h a v i b r a t i n g probe at depth was developed i n Germany d u r i n g the 1930's (Steuerman, 1939) , making i t one of the e a r l i e s t techniques of deep compaction. Subsequent developments of the technique have l e d t o the a v a i l a b i l i t y of a v a r i e t y o f techniques on the market today which make use of v i b r a t i n g probes f o r the improvement of both cohesive and c o h e s i o n l e s s s o i l s . One of the more r e c e n t l y developed of these techniques i s the "Phoenix Machine". This i s the name giv e n t o the p r o p r i e t a r y t o o l researched and developed by Phoenix 2 Engineering Limited of Vancouver, for the purpose of deep i n s i t u compaction of granular s o i l . The Phoenix Machine i s an attempt to increase the effectiveness of the established vibrocompaction method by the introduction of the novel concept of simultaneous v i b r a t i o n and drainage. The equipment comprises v i b r a t i n g and water pumping mechanisms within a single probe. As with other vibrocompaction equipment, the vibratory action of the probe i s believed to cause l o c a l i z e d l i q u e f a c t i o n of loose, saturated, granular s o i l s . The s o i l p a r t i c l e s are then able to compact under the p r e v a i l i n g conditions into a denser state of packing than existed previously. The advantage of the Phoenix equipment i s that the p a r t i c l e s are allowed to compact not only under stress conditions which include self-weight and overburden stresses, but also under the influence of a seepage force. Under such conditions i t i s contended that the s o i l i s able to achieve a denser state of packing than under purely v i b r a t i o n a l treatment alone. Although the Phoenix method has been successfully applied to densify the submerged, h y d r a u l i c a l l y placed sand f i l l s of the mobile caissons i n the Canadian A r c t i c (Stewart and Hodge, 1988), l i t t l e i s known about the technique. Fundamental questions a r i s e regarding the mechanism, performance and application of the process. I t i s unproven whether the technique a c t u a l l y achieves higher compaction than techniques operating s o l e l y with v i b r a t i o n . The a b i l i t y of the machine to densify a given s o i l i s unquantified, and 3 the mechanism responsible for increased compaction i s open to conjecture. The influence of operational parameters such as frequency, power and time spent densifying have not been well established. The object of t h i s thesis i s to investigate the influence and importance of these variables, and to s c i e n t i f i c a l l y evaluate the performance of the Phoenix Machine. I t i s also intended to quantify the improvement to s o i l conditions brought about by the Phoenix treatment, and therefore, to permit insight into the mechanism responsible f o r the Phoenix ground d e n s i f i c a t i o n process. 1.2 Scope To investigate the behaviour of the Phoenix equipment and quantify the influence of the various parameters on the a b i l i t y of the equipment to densify s o i l , a c a r e f u l l y designed programme of f i e l d tests was conducted at a l o c a l s i t e . I t was considered that the performance of the system should be evaluated so that i t could be compared against other d e n s i f i c a t i o n systems. I t was also sought to investigate some of the fundamental parameters a f f e c t i n g the mechanism of the d e n s i f i c a t i o n process. In summary, the investigative programme had the following objectives: i ) To quantify the a b i l i t y of the Phoenix Machine to densify the cohesionless s o i l s at the Annacis North Pier s i t e . 4 i i ) To consider the ef f e c t s of spacing and pattern on the degree of compaction achievable using the Phoenix equipment. i i i ) To investigate the influence of frequency on the performance of the Phoenix equipment. iv) To evaluate the importance of time spent densifying. v) To investigate i f the strength gain imparted during the Phoenix d e n s i f i c a t i o n process i s a time dependent process. v i ) To quantify the importance of the drainage component i n the process, and, v i i ) F i n a l l y , to attempt to monitor ground improvements as they occurred by performing ground v i b r a t i o n monitoring. S o i l conditions at the chosen s i t e proved to be less than i d e a l to demonstrate the capacity of the Phoenix equipment, and i n combination with equipment f a i l u r e s , reduced the amount of data available for analysis. To improve the data base, re s u l t s c o l l e c t e d from the f i e l d t ests has been supplemented by the addition of information which was recorded from e a r l i e r , developmental tests performed by Phoenix Engineering. These te s t s , performed i n 1987 were conducted at the same s i t e as those performed 5 s p e c i f i c a l l y for t h i s investigation. Evaluation of the data has shown i t to be of adequately high qu a l i t y for comparison with the research t r i a l s performed i n the context of t h i s investigation. 6 2. REVIEW OF VIBROCOMPACTION PRACTICE The purpose of t h i s chapter i s to review the exi s t i n g geotechnical l i t e r a t u r e dealing with techniques of i n place d e n s i f i c a t i o n of cohesionless s o i l s using processes of vibrocompaction. Vibrocompaction i s the method of deep den s i f i c a t i o n of i n s i t u granular s o i l s by means of rearranging sand grains into a denser state by in s e r t i o n of a v i b r a t i n g probe (ASCE, 1987). The term v i b r o f l o t a t i o n has been applied equally to stone column formation i n cohesive s o i l s and to the vibrocompaction of cohesionless s o i l s whether or not b a c k f i l l s o i l i s added to the hole. Stone column formation i s a fundamentally d i f f e r e n t process to the vibrocompaction of granular s o i l s and has been excluded from the current review. I t i s contended that the process of vibrocompaction i s b a s i c a l l y unaltered by the placing of b a c k f i l l s o i l i n the bore, assuming such b a c k f i l l i s of a s i m i l a r nature to the natural s o i l i n the bore. Accordingly such practices are covered i n t h i s review. 2.1 Vibrocompaction Procedure The improvement of s o i l s at depth using a v i b r a t i n g probe was f i r s t performed i n Germany over f i f t y years ago, and reported i n the English language by Steuerman (1939). He described what was to become the most widely used deep improvement process and has since become known as the 7 v i b r o f l o t a t i o n process. The technique was i n i t i a l l y used i n cohesionless s o i l s only, and could be performed without the use of imported b a c k f i l l . As such, the o r i g i n a l process was a true vibrocompaction technique. Subsequently coarse sand or gravel b a c k f i l l was added to the probe hole, the technique was adapted to use i n cohesive s o i l s , and the vibroreplacement process was established. The v i b r a t i n g probe used for compaction of loose sand i s often termed a v i b r o f l o t . I t consists of a vibrating t i p unit and follow up pipes, and i s most e f f i c i e n t l y deployed from a crane unit. The v i b r a t i n g probe i s penetrated into the s o i l to a depth a l i t t l e i n excess to which improvement i s sought. The equipment may be equipped with water j e t s to f a c i l i t a t e i n s e r t i o n into the ground. The vibrating probe i s subsequently retracted from the ground i n stages, whilst top water j e t s carry sand to the bottom of the bore. A description of the fundamentals of an early v i b r o f l o t and i t s operation i s given by D'Appolonia (1953), with more recent developments of the system being reported by Brown (1977), ASCE (1978), and M i t c h e l l (1981). The v i b r a t i n g t i p of a v i b r o f l o t generates horizontal vibrations at a frequency of about 3 0 Hz by means of turning an eccentric weight on a v e r t i c a l axis. The vibrator may be powered by an e l e c t r i c or by a hydraulic motor. The generation of l a t e r a l v i b r a t i o n a l forces at the t i p i s one of the c h a r a c t e r i s t i c s of the v i b r o f l o t . I t i s from the 8 l a t e r a l vibrations that the compacting e f f i c i e n c y i s derived since the v i b r o f l o t i s able to compact s o i l r a d i a l l y from the probe. It i s found that the sand density i s highest close to the probe and decreases approximately exponentially as the r a d i a l distance from the v i b r o f l o t increases (D'Appolonia, 1953). The spacing of probes depends on the s o i l conditions, the energy of the probe, and the l e v e l of improvement required. Probes are t y p i c a l l y employed on spacings of 1.5m to 4 m apart. I t i s usually found that vibrocompaction may i n fact loosen already dense strata, and that the compaction process i s i n e f f e c t i v e i n the top lm to 2m of s o i l . In such cases, the surface layer must be compacted by surface r o l l i n g or other means. The v i b r o f l o t a t i o n process has been used to compact sand deposits up to 30m deep. 2.2 Alternative Techniques of Vibrocompaction An alternative vibratory compaction technique has been described by Anderson (1974), i n which a v i b r a t i n g p i l e d r i v i n g apparatus i s mounted on the top of a 760mm diameter, open ended, tubular pipe. The pipe i s driven into and extracted from the s o i l to be compacted. The induced v i b r a t i o n i s v e r t i c a l , and no water j e t s are used. The frequency of the vibrations can be varied but i s normally around 15 Hz. In a comparison reported by Brown and Glenn (1976), i t was found that whilst the process was faster than the v i b r o f l o t a t i o n process, more and closer probe spacings 9 were required to achieve equivalent den s i t i e s . Overall the performance appeared to be i n f e r i o r to the v i b r o f l o t a t i o n process. Variations of the vibrating poker system have been accomplished by the use of di f f e r e n t probe configurations and s i z e s . S i m i l a r i t y exists i n a l l such systems i n that the probe i s vibrated v e r t i c a l l y , usually by means of vib r a t i n g p i l e d r i v e r type equipment. Saito (1977) described two types of probe used to densify hydraulic sand f i l l , both driven by vibratory p i l e d r i v e r s . One such probe used a hollow rod with four s t a b i l i z i n g f i n s at the base to make up a t o t a l diameter of 0.5m. The second probe comprised a closed, cone tipped pipe, 300mm i n diameter with 100mm high projecting tetrahedra spaced over the bottom 4m of the probe. Massarsch and Broms (1983) describe the v i b r a t i o n of a 15m long s t e e l rod with 0.8m wings spaced at 0.5m apart. I f necessary, i n s e r t i o n into the s o i l could be assisted by j e t t i n g at the bottom of the steel rod. Otherwise the method followed established vibrocompaction practices, being vibrated v e r t i c a l l y at about 20 Hz with vibratory p i l e d r i v i n g equipment. A large scale apparatus intended for offshore sand d e n s i f i c a t i o n has been described by Davis et a l . (1981). The vi b r a t i n g probe consisted of a tube with twelve r a d i a l f i n s 10 comprising a t o t a l diameter of 2.1m. Again the probe was vibrated v e r t i c a l l y from the top of the tube, at some 25 Hz. Four such vibrators, spaced at 6.5m could be deployed simultaneously from a pontoon, permitting d e n s i f i c a t i o n of a zone up to 26m wide, and up to 15m i n depth. A Y-probe or star p r o f i l e probe has been reported on by Wallays (1983). The probe has an e f f e c t i v e diameter of 1.0m. The Y-shape of the probe i s intended to eliminate s o i l plugging i n the corners i n the v i c i n i t y of the axis, otherwise deployment and operation of the probe i s apparently i d e n t i c a l to the method of Anderson (1974) described previously. A summary of the various vibrocompaction techniques available i s presented i n Table III and discussed i n Chapter 6.5. 2.3 Mechanism of Vibrocompaction When the v i b r a t i n g probe i s penetrated into the s o i l the vibratory action i s imparted to the s o i l p a r t i c l e s . The frequency of the s o i l p a r t i c l e s i s the same as the frequency of the vi b r a t o r unit, which i s determined by the speed of the d r i v i n g motor system. The intergranular forces between the cohesionless s o i l p a r t i c l e s are temporarily n u l l i f i e d and a zone of s o i l l i q u e f a c t i o n occurs i n the v i c i n i t y of the v i b r a t o r . Outside of t h i s zone, l i q u e f a c t i o n i s incomplete due to s o i l damping e f f e c t s . Damping w i l l be 11 increased with increasing fines content so the mechanism i s less e f f i c i e n t i n these s o i l s . The maximum amplitude of vibration i s obtained when the probe unit i s free l y suspended i n a i r . As the vibrator penetrates the s o i l , the resistance to penetration increases and hence the power demand of the vibrator to ensure continuous penetration increases also. Only i f s u f f i c i e n t power i s available can the maximum amplitude of vibratio n be maintained. The s o i l l i q u e f a c t i o n caused by the vi b r a t i o n permits the s o i l p a r t i c l e s to be rearranged under conditions of gravity and state of stress to assume a denser state of packing than previously existed. Cohesive s o i l s w i l l not tolerate slippage between the s o i l p a r t i c l e s and so the process i s in e f f e c t i v e i n such s o i l s . Water, expelled from the compacting granular s o i l below may appear at the ground surface (Massarch and Vanneste, 1988). The process works best when d e n s i f i c a t i o n i s attempted under saturated s o i l conditions (Brown, 1977). I f the water table i s not close to surface the addition of water to the bore can a s s i s t i n densifying the unsaturated s o i l s (Broms and Hansson, 1984). Not only does the v i b r o f l o t a t i o n process cause an increase i n packing of the s o i l p a r t i c l e s but i t also increases the state of horizontal stress i n the s o i l (Saito, 1977). I f the increase i n l a t e r a l stress i s not accounted for during post den s i f i c a t i o n i n s i t u monitoring, the state of r e l a t i v e density may be over-estimated. 12 2.4 Parameters Affecting Vibrocompaction S o i l improvement projects are undertaken by performing a regular pattern of improvement probes. Popular configurations are triangular spacings, since these o f f e r the most e f f i c i e n t coverage, but squares are common too. Thorburn (1975) proposed guidelines to estimate the l i k e l y degree of improvement achievable, but i t i s customary to perform a t r i a l at the s i t e of proposed s o i l improvement i n order to es t a b l i s h the optimum pattern and spacing of improvement probes. Such design relationships 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 l i k e l y w i l l vary from one project to another. When probes are spaced i n groups they may interact and create zones of high density between probes. The e f f e c t i s cumulative, and may be estimated using the 'influence factors' of D'Appolonia (1953). According to Sparks (1975), machine c h a r a c t e r i s t i c s can be expected to play a role i n the performance of a de n s i f i c a t i o n system. Important parameters include the size , frequency, amplitude and eccentric force. In an investigation of three machines i t was found that the higher powered machines were capable of compacting s o i l more uniformly i n the v i c i n i t y of the probe, whereas the lower powered machine led to a maximum density occuring some lm to 1.5m from the probe. In analyzing the res u l t s of these tests i t i s impossible to make firm conclusions since not only did 13 the machines have d i f f e r e n t operating frequencies and power outputs, but also were of d i f f e r e n t s i z e s . Morgan and Thomson (1983) investigated three machines but f a i l e d to iso l a t e the influence of machine c h a r a c t e r i s t i c s . The s o i l type affects the d e n s i f i c a t i o n capacity of the vibrocompaction process. The degree of d e n s i f i c a t i o n achieved decreases with increasing clay content of the sand, the technique being found e f f e c t i v e i f the non-plastic fines content remains below 20%. However, success has been claimed i n s l i g h t l y cohesive s t r a t i f i e d s o i l s , and granular s o i l s with cohesive inclusions (Webb and H a l l , 1969). Additionally, the radius of the zone of influence of a v i b r o f l o t decreases with increasing clay content. The zone of influence may decrease from 1.5m i n clean sand down to 0.75m i n sand with 20% fines (Webb and H a l l , 1969). In a case quoted by Harder et a l (1984), v i b r o f l o t a t i o n was unable to densify a s i l t y sand eit h e r due to s i l t within the sand to be densified, or due to the presence of an overlying cap of s i l t and clay. I t i s believed that i n both cases drainage from the densifying s o i l would be retarded and impede d e n s i f i c a t i o n . I t has been acknowledged that a decrease i n penetration resistance may accompany attempts at compaction i n sands with fines (Webb and H a l l , 1969). Figure 1 shows the range of s o i l types suited for improvement by vibrocompaction. S o i l s f a l l i n g e n t i r e l y within the l i m i t s of Zone II respond best to the process. 14 Figure 1. Range of Soil Types Suitable for Improvement by Vibrocompaction (after Brown, 1977) . 15 Portions of the grain s i z e curve may f a l l outside of Zone II , but any s o i l f a l l i n g e n t i r e l y inside Zone I w i l l prove d i f f i c u l t to compact. Gravels, and dense sands f a l l i n g within the l i m i t s of Zone III may prove d i f f i c u l t to penetrate and uneconomic to compact with vibrocompaction (Brown, 1977). The qua l i t y of workmanship may be expected to influence the r e s u l t s of vibrocompaction treatment (Brown, 1977) . Low sand densities caused by poor workmanship are often attributed to an inadequate supply of b a c k f i l l sand at the vi b r a t i n g t i p . Such a condition may r e s u l t from inadequate supply at the surface, caving of the bore preventing downward passage of f i l l material, or extracting the probe too r a p i d l y . Model studies by Metzger and Koerner (1975) indicated that the f i n a l density achieved during compaction was dependent on the i n i t i a l density, the higher f i n a l densities being associated with higher i n i t i a l d e n s i t i e s . A d d i t i o n a l l y , i t was shown that densities lower than those achievable at several diameters from the probe could r e s u l t i n the region d i r e c t l y under the probe i t s e l f . In the model studies i t was found that maximum power consumption occurred during compaction, although t h i s contradicts wide f i e l d experience where i t i s found that maximum power consumption accompanies maximum compaction. 16 According to M i t c h e l l (1981), the strength of ground densified by vibrocompaction may increase with time. They c i t e a case at Australia's Kwinan Terminal where cone penetration tests indicated a 10-15% gain i n the three weeks following treatment. Extensive evidence of M i t c h e l l and Solymar (1984) demonstrated the time dependent nature of increases i n s t i f f n e s s , strength and penetration resistance following i n s i t u deep de n s i f i c a t i o n . The d e n s i f i c a t i o n treatment may i n i t i a l l y lead to reduced penetration resistance, compared to the value before treatment, before the strength gain process takes e f f e c t . The strength gain process may continue over days or months. 2.5 Compaction Control Compaction control i s performed t y p i c a l l y by using i n s i t u t e s t i n g techniques, with current practice favouring the rapid and economic cone penetration t e s t . The f l a t dilatometer t e s t can also provide compaction control information and data on the strength and deformation c h a r a c t e r i s t i c s of the s o i l (Campanella and Robertson, 1983; Lacasse and Lunne, 1986). Since the i n s i t u l a t e r a l stress may be modified by the compaction process, care must be exercised i n the u t i l i z a t i o n of conventional i n s i t u test interpretation methods otherwise erroneous s o i l parameters may be deduced. Terms such as 'apparent r e l a t i v e density' have been coined to express the post treatment s o i l conditions. The inadequacy of r e l a t i v e density as a s o i l 17 parameter and problems i n interpretation post compaction due to secondary influences has led to the cone penetration resistance being the most widely used parameter for control of compaction. The state of d e n s i f i c a t i o n i s frequently estimated during the compaction process by monitoring the power input to the drive motor. According to D'Appolonia (1953) the power input reaches a maximum when the maximum s o i l density has been reached. Monitoring the power requirement of the v i b r o f l o t enables an assessment to be made to withdraw the probe to the next stage when a predetermined resistance has been met. However, the method requires experience on the part of the operator and cannot always be r e l i e d upon to account f o r discrepancies i n compaction which may be revealed by subsequent penetration t e s t i n g . Another method of control has been reported by Morgan and Thomson (1983), i n which the vibratory movement of the probe was measured with transducers to i n f e r the state of ground density. Vibration measurements were made with accelerometers mounted i n the t i p of the probe. I t was found that the horizontal amplitude of the probe decreased with increasing sand density, as determined from subsequent penetration t e s t s . Such a method i s a d i r e c t measurement of ground response and hence i s p o t e n t i a l l y more r e l i a b l e than the previously used method of power transmission. An alternative method has been attempted where vib r a t i o n 18 monitoring equipment was placed on the ground surface at set distances from the probe (Massarch and Vanneste, 1988). However, such a system poses a d i f f i c u l t problem of interpretation. 2.6 Development of Phoenix Concept Hodge (1988) demonstrated the b e n e f i c i a l e f f e c t of pumping water from model submerged sand f i l l s during placement. Permanent improvements i n the state of r e l a t i v e density and to the engineering behaviour of the f i l l resulted. These included increased resistance to scour erosion and increased angles of natural repose of the f i l l . The r e s u l t s constituted the basis f o r the proposal that a probe which could vibrate and simultaneously drain water from the s o i l , would out-perform a probe developing v i b r a t i o n only. Theory was put into practice when the prototype 'vibrodrain' was used to densify the periphery of the sand core of the mobile a r c t i c caisson Moliqpak (Stewart and Hodge, 1988). The equipment was deployed at 3 metre centres to successfully densify a 6 metre wide s t r i p adjacent to the caisson walls which could not be attempted by b l a s t i n g techniques. 2.7 Summary In summary, a s i g n i f i c a n t body of information i n the geotechnical l i t e r a t u r e exists which describes experience with vibrocompaction. I t concentrates primarily on the 19 a b i l i t y of any given technique to perform d e n s i f i c a t i o n operations. Much has been written about the effects of s o i l type, of probe spacing and pattern, which re l a t e primarily to performance. More recently, attempts have been made to understand the fundamental s o i l mechanics aspects of the d e n s i f i c a t i o n process, such as the possible time dependency of the process. The pore pressure behaviour during the d e n s i f i c a t i o n process has yet to be adequately described. Also unclear are the ef f e c t s of operating parameters such as frequency, amplitude, power input, and equipment dimensions and c h a r a c t e r i s t i c s . 20 3. RESEARCH SITE F i e l d t e sts were carried out to investigate the Phoenix densification equipment at a s i t e located adjacent to the Fraser River, on Annacis Island, Vancouver, B.C.. The s i t e i s situated on land owned by the Ministry of Highways of B r i t i s h Columbia, and constitutes an a r t i f i c i a l promontory b u i l t adjacent to the north bank of the Fraser River to prevent ship c o l l i s i o n damage to the north tower of the Alex Fraser Bridge. The s i t e was chosen for t e s t i n g since i t was known to comprise loose sand f i l l which i t was hoped would be well suited to compaction by the Phoenix process. 3.1 Regional Geology The geology of the Fraser River delta i s described by Blunden (1973). The region i s underlain by Pleistocene t i l l sheets and T e r t i a r y bedrock at depths of up to 275m below mean sea l e v e l . I s o s t a t i c rebound and post g l a c i a l sedimentation has resulted i n the formation of the Fraser River delta complex, which includes Annacis Island. The general sedimentary sequence on the Island consists of up to 40m of d e l t a i c and d i s t r i b u t a r y f i l l deposits. These consist predominantly of fi n e to medium sand with minor interbedded s i l t beds, and are overlain i n part by sand, s i l t or s i l t y clay loam overbank deposits. Marine clays and s i l t s which constitute the pro-delta deposits underlie the sand and s i l t sequence. 21 3.2 S i t e D e s c r i p t i o n The l o c a t i o n o f Annacis I s l a n d and the t e s t s i t e are depicted i n Figure 2. The t e s t s i t e i s a t the south s i d e of Annacis I s l a n d f a c i n g a s t r e t c h of the F r a s e r R i v e r known as C i t y Reach. The t e s t area formerly c o n s t i t u t e d p a r t of the r i v e r , but now comprises a promontory which p r o t e c t s the north p i e r of the r e c e n t l y c o n s t r u c t e d Alex F r a s e r Bridge. The promontory was constr u c t e d by i n f i l l i n g dredged sand f i l l behind an a r t i f i c i a l dyke b u i l t o f r o c k f i l l . A l a y e r of gravel some 300mm t h i c k has been p l a c e d a c r o s s the e n t i r e s i t e t o f a c i l i t a t e t r a f f i c k i n g . A hard s u r f a c e c r u s t up t o 2m t h i c k has developed across the s i t e . The ground surface i s s i t u a t e d at about +2m above mean sea l e v e l , i s l e v e l , and a f f o r d s easy v e h i c u l a r access. The f i l l sand had been dredged from the F r a s e r R i v e r and was p l a c e d through water. I t r e s t s d i r e c t l y on the previous r i v e r channel d e p o s i t s . I n v e s t i g a t i o n s performed fo r the brid g e s t r u c t u r e suggest the t h i c k n e s s of sand f i l l i n c r eases from n i l a t the o l d r i v e r bank up t o 11m at the s i t e of the bridge p i e r . I t had been hoped t o perform the t e s t s of t h i s i n v e s t i g a t i o n i n an area t o the south of the previous t e s t s , Figure 3, where sand f i l l would be at i t s t h i c k e s t . In the event, the panel o f ground assigned t o the f i e l d t r i a l s of t h i s i n v e s t i g a t i o n l i e s between the area of o r i g i n a l Phoenix f i e l d t e s t s and the o l d ri v e r b a n k . Whilst the e a r l i e r t r i a l s had enjoyed some 9m of sand f i l l , i t was discovered t h a t the f i l l i n the area o f t r i a l s f o r t h i s 22 Figure 2. Map of Lower Mainland Area Showing Location of Research S i t e . 23 Figure 3. Plan of Annacis North Pier Research S i t e Showing Locations of Test Areas. 24 i n v e s t i g a t i o n was i n s u f f i c i e n t f o r d e n s i f i c a t i o n purposes and the work had t o be conducted i n the u n d e r l y i n g d e p o s i t s of na tu r a l F r a se r R i v e r Sand. As a consequence, due c o n s i d e r a t i o n had t o be made i n comparing the two se ts of f i e l d da t a , s i n ce not on ly were the s o i l s o f d i f f e r e n t cha rac te r i n terms o f o r i g i n , age, and s i l t con ten t , but compaction ope r a t i ons were performed w i th d i f f e r i n g overburden c o n d i t i o n s . The h y d r a u l i c f i l l sand i s a g r e y , l o o s e , s i l t y sand, wi th o c c a s i o n a l f i n e g r a v e l . The r i v e r channe l depos i t s c o n s i s t o f 2-3m o f g rey , s o f t s i l t . Beneath the s i l t l i e s the F r a se r R i v e r Sand, a g rey , f i n e and medium sand, s i l t y i n p a r t . The presence o f the s i l t l a ye r l e d t o d i f f i c u l t i e s i n a ch i e v i ng r e p e a t a b i l i t y of the Phoenix p robes . T h i s i s a t t r i b u t e d t o s t a r v a t i o n of b a c k f i l l sand a t the t i p of the probe . Ac co rd ing t o Brown (1977), i f the v i b r a t i n g probe i s s ta rved o f b a c k f i l l i t r a t t l e s around i n the open bore without t r a n s m i t t i n g v i b r a t i o n s to the s o i l . Phoenix probes were performed w i thout the a d d i t i o n o f b a c k f i l l , and r e l i a n c e p l a c e d on the downward m i g r a t i o n o f g r anu l a r s o i l from h ighe r i n the bo re . There i s ev idence to i n d i c a t e t ha t the s i l t l a y e r too c o l l a p s e d i n to the b o r e , l e a d i n g d i r e c t l y to poor cone r e s i s t a n c e s measured i n the compacted bore . S i l t c o l l a p s e i n t o the bore would l e a d to g e n e r a l l y poor compaction r e s u l t s due to b l o ck i ng o f f o f the supply o f 25 b a c k f i l l a t the t i p , a mechanism a l s o d e s c r i b e d by Brown (1977) . F i g u r e 4 d e p i c t s the g r a i n s i z e c h a r a c t e r i s t i c s of the sands i n which d e n s i f i c a t i o n was attempted. The grading of the F r a s e r R i v e r Sands f a l l s a t the border between Zone I and Zone I I o f F i g u r e 1, w h i l s t the g r a d i n g curve of the f i l l sand f a l l s p a r t l y w i t h i n Zones I and I I . According t o Brown (1977), the s o i l s are t h e r e f o r e l i a b l e t o improvement by vibrocompaction, but are too f i n e t o be c o n s i d e r e d i d e a l l y s u i t e d t o compaction by t h i s method. The high content of s i l t i n the F r a s e r R i v e r Sands caused problems t o the Phoenix f i l t e r system s i n c e the f i n e s o i l s d i d not wash through the f i l t e r but tended t o c l o g the f i l t e r system, p r e v e n t i n g water flow. In a d d i t i o n a h i g h s i l t content would reduce the e f f i c i e n c y of the Phoenix probe due t o a r e d u c t i o n i n s o i l p e r m e a b i l i t y . However, the piezocone data at the s i t e would suggest the sands t o be f r e e l y d r a i n i n g . The groundwater l e v e l at the s i t e v a r i e s with t i d a l f l u c t u a t i o n and season but t y p i c a l l y i s found a t 1 t o 3m below ground l e v e l . In t h i s r e s p e c t a l l but the near s u r f a c e s o i l s f u l f i l the requirement of s a t u r a t i o n necessary f o r good vibrocompaction r e s u l t s . T h i s was o f p a r t i c u l a r importance i n c o n s i d e r i n g the s i t e f o r Phoenix t e s t s , s i n c e the unique c h a r a c t e r i s t i c of the equipment r e l i e s on submergence. 26 Figure 4. P a r t i c l e Size D i s t r i b u t i o n Curves For F i l l Sand and Fraser River Sand. 27 4. EQUIPMENT AND PROCEDURES This section of the thesis describes i n d e t a i l the equipment and operating procedures of the Phoenix d e n s i f i c a t i o n system. The i n s i t u t e s t s performed for compaction control are b r i e f l y described, along with the objectives and content of the f i e l d t e s t programme. 4.1 The Phoenix Densification Equipment The •Phoenix Machine' or 'vibrodrain' are the names applied to the s o i l d e n s i f i c a t i o n system developed by Phoenix Engineering of Vancouver. The equipment achieves d e n s i f i c a t i o n of s o i l i n s i t u by the combined action of v i b r a t i o n and pumping water from the s o i l . The equipment comprises a probe which i s capable of generating l a t e r a l v i b r a t i o n and simultaneous suction pressure. The probe i s lowered into the s o i l on a custom designed d r i l l s t r i n g which may be deployed from a regular top-drive rotary d r i l l r i g . The probe i s able to penetrate without j e t t i n g , but i f necessary the equipment could be configured to accommodate a j e t t i n g procedure. Once at a depth s l i g h t l y i n excess of that to which improvement i s sought, the probe i s slowly retrieved. The probe may be repeatedly plunged into and retrieved from the bore to achieve the required de n s i f i c a t i o n . An experienced operator can detect compaction by increased resistance to penetration on the downward plunge. 28 The probe i s a torpedo shaped unit of the s t y l e of the well described v i b r o f l o t , but with the addition of a water pumping mechanism above the v i b r a t i n g t i p . Figure 5 shows the p r i n c i p a l equipment d e t a i l s and dimensions. The probe i s 7.5 inches i n diameter and i s b u i l t i n two sections. The lower or t i p section houses the v i b r a t i n g unit, whilst the upper section comprises the pumping system. A i r at 100 p s i of pressure i s conveyed v i a the custom d r i l l pipes to the t i p of the probe where i t powers an a i r motor. The motor rotates the 87 l b eccentric mass on a v e r t i c a l axis and develops horizontal vibrations. The frequency of vibrations i s found to be nominally 25 Hz. A c e n t r i f u g a l force of 2.3 tons i s developed, which i s small i n comparison to v i b r o f l o t a t i o n equipment, which may generate forces up to 25 tons (Jebe and Bartels, 1983) . The pumping or drainage unit i s located immediately behind the v i b r a t i n g t i p section. As a i r e x i t s the motor unit i t passes up to the top of the drainage section where the discharge causes an a i r l i f t e f f e c t which develops a suction pressure across the f i l t e r screen. The screen s i z e has to be designed according to the s o i l c h a r a c t e r i s t i c s , since i t acts as a f i l t e r unit and should only permit the inflow of water. I f the screen size i s chosen too small there i s a tendency for the system to clog. On the other hand too large an aperture leads to s o i l being pumped from the bore. The probe design i s such that the f i l t e r unit can Figure 5 Schematic of Phoenix Den s i f i c a t i o n Probe. 30 e a s i l y be replaced or changed for a f i l t e r of d i f f e r e n t sized aperture should s o i l conditions dictate. Two designs of f i l t e r screen were tested during the development of the Phoenix Machine, including well screens and perforated tubing with f i l t e r mesh. The well screen system u t i l i z e d a 6 inch "pipe s i z e " Johnson s t a i n l e s s s t e e l well screen. The seepage section i s 60 inches o v e r a l l length with 48 inches of open screen. The screen i s formed of s p e c i a l l y shaped 0.1 inch wide wire which i s h e l i c a l l y wound around v e r t i c a l r i b s to give 6.625 inch outside diameter. The system worked well but the screens were l i a b l e to damage and t h e i r replacement proved cost l y . The alternative system consisted of a f i l t e r screen mesh sheathed within a strong perforated tube. The tube both protected the mesh against tearing and abrasion, and provided some st r u c t u r a l i n t e g r i t y to the system. The mesh si z e adopted was 40 openings per inch. The perforated tube contained some 360 holes, each 1.625 inches i n diameter, and d r i l l e d on a t r i a n g u l a r pattern at 3 inch spacing. I t was found that at the t e s t s i t e the holes tended to block with f i n e sand. Once blocked, the e f f i c i e n c y of the pumping system was l o s t . Water sucked into the drainage unit i s ca r r i e d upwards i n the annulus of the d r i l l pipes. On reaching the top of the d r i l l s t r i n g a swivel unit permits the exhaust a i r and groundwater mixture to discharge into a waste pipe. By 31 monitoring the volume of f l u i d discharging from the pipe a qua l i t a t i v e assessment can be made of how e f f i c i e n t l y the pumping mechanism i s performing, and can indicate i f the correct choice of f i l t e r screen s i z e has been made. When the drainage unit was i n f u l l operation the rate of water discharge was estimated at 3 0 gallons/minute. The d r i l l pipes used were s p e c i a l l y designed for use with the Phoenix Machine. D r i l l pipe lengths were furnished i n f i v e foot lengths with an outside diameter of 5i inches. Short d r i l l pipe lengths were chosen for t h e i r f l e x i b i l i t y i n working i n confined conditions such as were encountered on the Molikpaq project. The configuration of d r i l l pipes was such that an inter n a l central tube c a r r i e d a i r from the surface to the t i p of the probe and the returning a i r and water mixture was piped through the d r i l l s t r i n g annulus. Pressure i n t e g r i t y was maintained by O-ring seals within the pipes. The Phoenix d e n s i f i c a t i o n equipment was deployed from a Simco 5000 d r i l l r i g , owned and operated by Foundex Limited of Vancouver. Compressed a i r requirements were furnished by an Ingersoll-Rand Type 750/355 a i r compressor. This i s a large machine capable of de l i v e r i n g 750 cubic feet/minute swept a i r capacity at 100 p s i . From previous Phoenix experience t h i s compressor was capable of powering two den s i f i c a t i o n systems simultaneously. The e a r l i e r t e s t s by Phoenix had demonstrated that a compressor of 350 cubic 32 feet/minute swept a i r capacity at 100 p s i was quite adequate to power a single Phoenix Machine. 4.2 In Situ Tests In s i t u t ests were performed to investigate the geotechnical conditions at the s i t e and to monitor the performance of the Phoenix equipment. This section of the thesis describes the procedures and techniques employed i n carrying out the various i n s i t u t e s t s . Generally, i n s i t u tests were performed i n accordance with the procedures recommended by the American Society for Testing and Materials (ASTM, 1986; Schmertmann, 1986). In the absence of any designated standards the procedure followed usual UBC practice, which has evolved through wide geotechnical f i e l d t e s t i n g experience. 4.2.1 Testing Vehicle A l l i n s i t u t ests were performed from the research vehicle of the s o i l s group of the University of B r i t i s h Columbia, of which a description i s given by Campanella and Robertson (1981). This i s a purpose designed, s e l f contained truck from within which a variety of f i e l d t e s t s may be performed. The truck i s equipped to perform tests with a mechanical cone, e l e c t r i c and seismic piezocones, f l a t dilatometer, screw plate, f i e l d vane, s e l f boring and f u l l displacement pressuremeter, together with the a b i l i t y to retr i e v e piston samples. 33 4.2.2 Tests Performed According to Campanella and Robertson (1982), i n s i t u tests may be broadly divided into two categories: logging methods and s p e c i f i c methods. Logging methods are generally economic and quick to perform, and are used primarily for st r a t i g r a p h i c p r o f i l i n g . They can also y i e l d q u a l i t a t i v e estimates of geotechnical parameters based on empirical correlations (Robertson and Campanella, 1983, 1986). S p e c i f i c t e s t methods are often slower and more costly than logging methods, and are used primarily for the measurement of s o i l properties at a point. The logging methods are therefore best suited to the preliminary evaluation of s o i l parameters. The cone penetration t e s t i s the most rapid of the i n s i t u t e s t s and the addition of the pore pressure measuring element has improved evaluation of s o i l parameters. Consequently the e l e c t r i c piezocone was selected as the primary tool for evaluation of the performance of the Phoenix Machine. The f l a t dilatometer was used s e l e c t i v e l y , primarily to attempt to i d e n t i f y changes i n horizontal stress and assess changes i n s o i l modulus. Tests were also performed with the seismic piezocone to provide information on dynamic shear modulus before and afte r treatment. 4.2.3 Piezocone Penetration Test (CPTU) Piezocone tests were performed using cones with 10 sq cm base area and 60° apex angle, i n accordance with 34 recommended test procedures (ASTM, 1986). The majority of soundings were performed with a Hogentogler, 10-ton, subtraction type "Supercone", but a UBC made independent bearing-friction type instrument was also used. Details of the various piezocone designs are given by Campanella and Robertson (1988). For both cones the pore pressure sensing element was located immediately behind the t i p . The UBC cone had the capacity to measure pore pressures simultaneously behind the f r i c t i o n sleeve, but since only three penetration tests were performed using such a cone, only pore pressure data from behind the cone t i p have been used i n interpretation for the present study. Measurements of pore water pressure, cone bearing, sleeve f r i c t i o n , and i n c l i n a t i o n were recorded every 25 mm of penetration. In addition, the UBC cone measured temperature. Depending on cone design, cone measurements can be susceptible to temperature variation, therefore corrections may be necessary to compensate for such changes (Campanella and Robertson, 1988). Before going out into the f i e l d each cone was checked for operation, c a l i b r a t i o n and then c a r e f u l l y saturated. Porous polypropylene f i l t e r elements 5mm wide were saturated with glycerine under a vacuum i n the laboratory. The instrument had to be c a r e f u l l y assembled under glycerine to eliminate a i r from the pressure measurement system, and kept under glycerine u n t i l ready to test. F u l l d e t a i l s of the 35 saturation procedure i n practice at UBC can be found in Robertson and Campanella (1986). To confirm instrument ca l i b r a t i o n , instrument baselines were recorded before and after every sounding. In the f i e l d , cone data were recorded automatically using the Hogentogler data acquisition system in the UBC Geotechnical Research Vehicle. This system consists of a Radio Shack LED display portable computer, a l i n e printer, and a bubble memory storage device. Once back at the laboratory cone data was downloaded from the bubble device onto a personal computer and processed using CONEPLOT and CPTINTRP. The e a r l i e r cone tests were performed by Western Geosystems for Phoenix, and u t i l i z e d a standard 10 sq cm piezocone manufactured by Geotech of Sweden. Again the pore pressure element was located behind the t i p . The cone was pushed from a d r i l l r i g . Measurements were recorded every 50 mm of penetration of cone bearing, sleeve f r i c t i o n and pore pressure only. 4.2.4 Flat Dilatometer Penetration Test (DMT) The f l a t dilatomer i s a recently developed, rapid and cost e f f e c t i v e , i n s i t u testing device. It. consists of a f l a t blade, with a 60mm diameter expandable s t e e l membrane on one face. The instrument i s pushed into the s o i l , good practice c a l l i n g for measurement of the penetration force. Once the test depth has been reached, the membrane i s 36 expanded with a high pressure gas supply. The pressure required to ju s t l i f t the membrane from i t s seating, the 'A' reading, and the pressure required to displace the membrane 1.1mm into the s o i l , the 1B 1 reading, are recorded. The membrane i s then deflated and the blade i s advanced to the next t e s t depth, usually 20cm deeper, where the procedure i s repeated. The t e s t thereby furnishes a discreet test p r o f i l e . The t e s t was performed i n accordance with the recommended standard procedure (Schmertmann, 1986). F u l l e r test procedures and equipment d e t a i l s are to be found i n Marchetti and Crapps (1981). Before t e s t i n g i t i s important to ensure that the instrument i s within cer t a i n s p e c i f i e d c a l i b r a t i o n l i m i t s . The c a l i b r a t i o n values enable consideration to be made for the s t i f f n e s s of the st e e l membrane, and fo r the outward curvature which the membrane acquires with use. The corrected membrane l i f t - o f f and 1.1mm displacement pressures can be used to define three intermediate index parameters, which Marchetti (1980) described as a material index, I D , a horizontal stress index, K D and a dilatometer modulus, E Q . From these indices, empirical relationships have been developed to determine regular geotechnical parameters. Details of the o r i g i n a l correlations may be found i n Marchetti (1980), with l a t e r developments by Schmertmann (1983) . 37 4.2.5 Seismic Piezocone Penetration Test (SCPTU) The incorporation of a velocity seismometer into a regular cone has made i t possible to routinely measure the shear wave ve l o c i t y at very small s t r a i n during a piezocone sounding (Robertson et a l . , 1986). From t h i s one can calculate the shear modulus at very low st r a i n , GMAX. The cone penetrometer containing the seismometer i s pushed to the f i r s t test depth. The seismometer i s oriented in the horizontal direction and perpendicular to the signal source to detect the horizontal component of shear waves. Shear waves are generated at the ground surface by s t r i k i n g the truck pads horizontally with a heavy hammer. Both sides of the truck are struck i n turn. At any tes t depth, two waveforms can therefore be obtained, representing oppositely polarized waves. A high quality oscilloscope i s necessary to record and view the waveforms. The procedure i s repeated at regular intervals of depth and the waveforms are interpreted according to the 'pseudo-interval 1 technique descibed by Robertson et a l . (1985), to obtain shear wave v e l o c i t i e s . By e l a s t i c theory, the maximum shear modulus i s related to the shear wave velocity according to the following relationship: 2 GMAX _ v s • P where v s i s the shear wave ve l o c i t y , and p i s the s o i l density. 38 Consequently i f an estimation of s o i l density i s available, one can make an evaluation of shear modulus. The shear s t r a i n amplitude i n seismic cone tests i s of the order of 1 0 ~ 4 , so a low s t r a i n l e v e l , dynamic shear modulus, Gj^^ i s obtained. 4 . 3 Scope of F i e l d Test Programme Figure 6 shows the locations of the Phoenix te s t series whilst Figure 7 shows i n d e t a i l the configurations of den s i f i c a t i o n probes and penetration t e s t s performed. Figures 7a and 7b show the t e s t programmes performed by Phoenix Limited during 1987 for the purpose of equipment development. These tests have been referred to by Phoenix as the PE, PH and F series of te s t s . The qual i t y of the data from these t e s t s was c a r e f u l l y s c r u t i n i z e d p r i o r to being employed for evaluation of the Phoenix probe. Figure 7c shows the positions of Phoenix probes and the penetration t e s t s performed from the UBC t e s t truck s p e c i f i c a l l y for t h i s investigation. This ser i e s of penetration tests has been designated with the p r e f i x 'ANP*. Table I d e t a i l s the ANP series of penetration t e s t s . A set of cone penetrometer te s t p r o f i l e s i s included in the Appendix. Due to equipment f a i l u r e , no d i g i t i z e d records could be made for the F series and these have had to be omitted from the Appendix. 39 Figure 6 Plan of Research Site Showing Locations of F i e l d Test Series 4 0 PE14 + PE10 P E S ; P ? 9 \ K " N P E A ? 4 a ^ PE3 + PEB + PEC +. PE SERIES + PE8 Figure 7a + PE7 PE6 3 m 3m + PH11 PH10 + ' + PH9 PH8 + / PH6 F9 P H I H ® — + — • + + " . X " + PH3 P" 5 fc„ F1 + .+ PH2 PH7 PH & F SERIES Figure 7b . ANP6 « + ANP19+15 ANP20- V ANP14+ + \ +ANP24 TANP36 , \ +ANP23 •G + ANP12 ANP22 ANP21 Series performed without drainoge element ANP SERIES Figure 7c PHOENIX PROBE ® PENETRATION TEST + ANP25 ANP29+ +«*5Slp27 P^28 5 A N K 2 7 + ANP26 • 4 + ANP7 ANP34 ® 3 ANP9 •J3 +ANP32 ANP33 + 9 2 + ANPD1 ^ANPSS + 11 + ANP30 « 1 ANP I performed 20m to SW of ANP aeries + ANP31 Figure 7 plan Showing Layout of Phoenix Probes and Penetration Tests Performed 41 The Phoenix probe holes associated with the ANP t e s t series have been numbered consecutively from 1 to 15, and are marked on Figure 7c accordingly. The configuration of the programme was designed to achieve the objectives describes i n Section 1.2, and to maximize data return for the l e a s t number of Phoenix probes. As a r e s u l t of s o i l compaction, s i g n i f i c a n t surface cratering of the s i t e was anticipated. This was a consideration i n designing the programme since i t was required to maintain adequate access for the i n s i t u t e s t i n g vehicle at a l l times. Test Test Type Test Depth Comments Number & Equipment Date (m) ANP1 Hogentogler Piezocone 18/08/88 9. 93 V i r g i n s o i l , 20m SW of Phoenix series. ANP5 Hogentogler Piezocone 01/09/88 14. 73 V i r g i n s o i l . ANP 6 Hogentogler Piezocone 09/09/88 20. 58 V i r g i n s o i l . ANP7 Hogentogler Piezocone 24/09/88 12. 48 V i r g i n s o i l . ANP9 UBC#7 Seismic 26/09/88 14. 77 V i r g i n s o i l . Piezocone ANP10 Hogentogler Piezocone 07/10/88 14. 43 At Probe #5. ANP11 Hogentogler Piezocone 07/10/88 15. 01 At Probe #10. ANP12 Hogentogler Piezocone 08/10/88 15. 81 At Probe #16. ANP14 Hogentogler Piezocone 14/10/88 13. 78 At mid-point of two Probes #14 & #15. ANP15 Hogentogler Piezocone 18/10/88 14. 61 At Probe #7. ANP16 Hogentogler Piezocone 18/10/88 14. 53 At mid-point of two Probes #7 & #10. ANP17 Hogentogler Piezocone 19/10/88 14. 68 0.6m from Probe #7 ANP18 Hogentogler Piezocone 19/10/88 13. 95 0.25m from Probe #7 Table I. Details of Penetration Tests Performed. 42 Test Test Type Test Depth Comments Number & Equipment Date (m) ANP19 Hogentogler 19/10/88 14 .48 0.4m from Probe #15 Piezocone without drainage. ANP20 Hogentogler 19/10/88 14 .63 0.85m from Probe #15 Piezocone without drainage. ANP21 Hogentogler 29/10/88 14 .58 0.55m from Probe #16 Piezocone without drainage. ANP2 2 Hogentogler 29/10/88 14 .63 0.2m from Probe #16 Piezocone without drainage. ANP23 Hogentogler 29/10/88 14 .10 0.45m from Probe #16 Piezocone without drainage. ANP24 Hogentogler 29/10/88 14 .63 0.85m from Probe #16 Piezocone without drainage. ANP25 Hogentogler 29/10/88 14 .53 0.55m from Probe #5 Piezocone ANP26 Hogentogler 29/10/88 14 .63 1.00m from Probe #5 Piezocone ANP27 Hogentogler 29/10/88 13 .35 0.35m from Probe #5 Piezocone ANP28 Hogentogler 29/10/88 13 .38 0.20m from Probe #5 Piezocone ANP29 Hogentogler 29/10/88 13 .48 0.85m from Probe #5 Piezocone ANP30 Hogentogler 04/11/88 13 .38 0.30m from Probe #1 Piezocone 6 minutes/metre. ANP31 Hogentogler 04/11/88 14 .20 0.60m from Probe #1 Piezocone 6 minutes/metre. ANP32 Hogentogler 04/11/88 13 .78 0.30m from Probe #2 Piezocone 4 minutes/metre. ANP33 Hogentogler 04/11/88 13 .65 0.60m from Probe #2 Piezocone 4 minutes/metre. ANP34 Hogentogler 09/02/89 12 .48 0.30m from Probe #3 Piezocone 2 minutes/metre. ANP35 UBC#7 Seismic 08/03/89 10 .73 Centroid of 1.5m Piezocone Phoenix Probes. ANP36 Hogentogler 21/01/88 13 .68 At 2.5m centroid Piezocone without drainage ANP37 Hogentogler 21/01/88 13 .76 Centroid of 2.5m Piezocone Phoenix probes. ANP38 Hogentogler 21/01/88 13 .81 Close v i c i n i t y to Piezocone Probe #5 ANPD1 Fla t 24/09/88 11 .00 V i r g i n s o i l . Dilatometer ANPD2 Fla t 27/01/89 12 .20 At Probe #10. Dilatometer Table I. Details of Penetration Tests Performed (continued). 43 Phoenix Date of Time Spent Drainage Comments Probe # Probe Densifying min/metre System 1 5/10/88 6 Mesh & cover Poor drainage 2 5/10/88 4 Mesh & cover Poor drainage 3 5/10/88 2 Mesh & cover Poor drainage 4 5/10/88 6 Mesh & cover Poor drainage 5 6/10/88 6 Wellscreen Good drainage 6 6/10/88 6 Wellscreen Good drainage 7 6/10/88 6 Wellscreen Good drainage 8 6/10/88 6 Wellscreen Poorer drainage 9 6/10/88 6 Wellscreen Poor drainage 10 7/10/88 6 Wellscreen Good Drainage 11 7/10/88 6 Wellscreen Poor drainage 12 7/10/88 6 Wellscreen Poor drainage 13 7/10/88 6 Wellscreen Poor drainage 14 8/10/88 6 - Vibration only 15 8/10/88 6 - Vibration only 16 8/10/88 6 — Vibration only Table I I . Details of Phoenix Densification Probes Table II summarizes the operating conditions under which the Phoenix probe holes, 1 to 16 i n c l u s i v e , were performed. To overcome the hard, gravelly surface crust at the s i t e , a l l Phoenix holes were pre-augered to 4.8m depth using an 8 inch diameter auger. For a l l probes conducted for th i s investigation, d e n s i f i c a t i o n was attempted over a depth range of 4.5m to 10.5m. The depths s p e c i f i e d were measured to the bottom end of the drainage unit, and therefore corresponded to the depths over which the combined processes of suction and vib r a t i o n were operational. The depth of treatment meant that den s i f i c a t i o n e f f e c t s could be investigated for both the s i l t and the sand s o i l s . No den s i f i c a t i o n treatment was attempted i n the s o i l s from surface down to 4.5m. During the previous tests performed by 44 Phoenix in the sand f i l l , the depth range over which densification was attempted was from 2m to 6m depth, which meant that treatment was performed exclusively within f i l l sand. In these tests no densification treatment was attempted in the s o i l s from surface to 2m. The Phoenix equipment experienced r e l i a b i l i t y and design shortcomings, and frequently the drainage equipment was i n e f f e c t i v e . This was caused primarily by fine sand blocking the screen openings and an i n e f f e c t i v e design of the drainage unit. The problem proved worse with the perforated pipe and mesh drainage system than with the well screen unit. As the screen became increasingly clogged with s o i l the e f f i c i e n c y of the unit as a water pumping system became progressively worse. The performance of the equipment reflected the fact that the Phoenix equipment i s s t i l l i n a developmental stage and has yet to be refined s u f f i c i e n t l y to operate at optimum ef f i c i e n c y . Despite the high s i l t content of the sands, they were s u f f i c i e n t l y permeable to be drained by the Phoenix equipment. A l l Phoenix probes were performed with an a i r supply pressure of 100 p s i , except probe #4 which was conducted at 120 p s i . In both cases the supply pressure proved to correspond to a nominal operating frequency of 25Hz. The Phoenix probes performed for the e a r l i e r developmental tests were executed using a time of densification of 6 minutes/metre. 45 5. INTERPRETATION AND IMPROVEMENT OF SOIL PARAMETERS FROM IN  SITU TESTS In s i t u t e sts were performed at the Annacis North Pier s i t e to estimate s o i l conditions p r i o r to improvement works. Further tests were performed at various times following s o i l d e n s i f i c a t i o n to investigate the influence of the Phoenix equipment on s o i l properties. The object of t h i s Chapter i s to examine the changes i n s o i l parameters which occur during treatment with the Phoenix equipment. In an assessment of s o i l improvement one must be i n a pos i t i o n to accurately estimate the s o i l conditions, otherwise the degree of improvement achieved cannot be confidently evaluated. For t h i s project only i n s i t u tests and the most recently developed interpretation methods have been employed to determine geotechnical parameters. Selected cone and f l a t dilatometer p r o f i l e s from the s i t e were used f o r interpretation. Cone p r o f i l e s ANP1 and ANP9 are representative cone p r o f i l e s performed p r i o r to treatment i n the f i l l and i n the underlying Fraser River Sand respectively. Interpretation of post d e n s i f i c a t i o n s o i l parameters i s based primarily on cone p r o f i l e s PE6 and ANP15, also performed i n the f i l l sand and Fraser River Sand respectively. These constitute the p r o f i l e s demonstrating the most s i g n i f i c a n t increases to cone resistance i n the hydraulic f i l l and natural Fraser River Sand respectively. 46 Cone bearing values uncorrected for pore water pressure e f f e c t s due to unequal end areas have been used throughout, since the correction makes l i t t l e difference i n the f r e e l y draining and shallow s o i l s as were encountered. 5.1 S o i l P r o f i l e The cone penetration test i s recognized for i t s accuracy and d e t a i l i n s t r a t i g r a p h i c logging work, and to a l l intents and purposes provides a continuous p r o f i l e with depth. The most widely adopted method of s o i l type i d e n t i f i c a t i o n from a cone penetration t e s t u t i l i z e s the cone bearing and f r i c t i o n r a t i o , defined by the r a t i o of sleeve f r i c t i o n and cone bearing. Robertson (1985) has produced the s o i l behaviour type c l a s s i f i c a t i o n chart shown i n Figure 8, which u t i l i z e s these parameters and i s based on a combination of UBC experience and e a r l i e r work by Douglas and Olsen (1981). Figure 8 was used to a s s i s t the interpretation of s o i l types from cone penetration p r o f i l e s ANP1 and ANP9, and the r e s u l t i n g s o i l p r o f i l e s are indicated i n Figures 9 and 10, respectively. Referring to cone p r o f i l e ANP1, the s o i l throughout most of the p r o f i l e has been i d e n t i f i e d primarily as sand, with s i l t . Below a hardened surface crust, the cone p r o f i l e indicates a very uniform material, p a r t i c u l a r l y to 6m depth. The chart of Figure 8 does not u t i l i z e pore pressure information which can greatly enhance s o i l i d e n t i f i c a t i o n . Pore pressures down to 9m are hydrostatic i n d i c a t i n g a 47 Zone S o i l Behaviour Type 1 se n s i t i v e f i n e grained 2 organic material 3 clay 4 s 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 8 sand to s i l t y sand 9 sand 10 gravelly sand to sand 11 very s t i f f f ine grained* 12 sand to clayey sand * overconsolidated or cemented Figure 8 S o i l Behaviour Type C l a s s i f i c a t i o n Chart (after Robertson 1985). U B C I M I T U T E S T I N G S i t o L o c a t i o n ! ANNACIS NORTH PIER On S i t o Loc i 20m SW OF ANP SERIES CPT Da ta i 18/B/B8 C o n * U » o d . UBC#7 STD PP F l l o . ANP1.EDT Commanti i PRE TRIAL (0 QI L +J (V E 0_ LU a FRICTION RATIO Rf (I) Q 5 SLEEVE FRICTION (bar) & — I I I I — o CONE BEARING 0c (bar) PORE PRESSURE U (a. of *otar) 10 Q . 40 DIFFERENTIAL P.P. Ratio AU/Oc INTERPRETED PROFILE SAND TO SLTY SANE 10-15 SAND SILTY SAND SAND TQ SILTY SAND CLAYEY SILT SANDY SILT Dopth Increment • . 0 2 3 m Max Dopth i 9 .93 m Figure 9 Cone Penetrometer P r o f i l e ANP1 Showing Interpreted S o i l P r o f i l e . FILL SAND 03 RIVER CHANNEL DEPOSITS U B C I M S I T U T E: S " r i M G S i t e L o c o t l o m ANNACIS NORTH PIER CPT D a t a i 28/09/88 F U q i ANP9.EDT On S i t e Loc i Cone Usadt UBC 07 STO PP Commantot PRE TRIAL SCPT CO 01 e •p a E 0_ LU a FRICTION RATIO Rf (J) 0 5 SLEEVE FRICTION (bar) -0 ? COKE BEARING 0c (bar) PORE PRESSURE U (a. of water) -10 Q 40 0 DIFFERENTIAL P.P. Ratio AU/Oc 2 n .8 Dopth Incramant • .025 m Max Dap th i 14. 77 m Figure 10 Cone Penetrometer P r o f i l e ANP9 Showing Interpreted S o i l P r o f i l e . io is INTERPRETED PROFILE GRAVELLY SAND TO SAND SAND SAND TO SILTY SAND 31.TY SAND TO SAN0YSB.T SANDY SIT TO CLAYEY SIT SAND inn oca SILTY SAND F i a SAND RIVER CHANNEL DEPOSITS FRASER RIVER SANDS f r e e l y draining sand material. The material i s interpreted to be loose, sand f i l l . At 9m there i s an increase i n pore pressure accompanied by a decrease i n cone bearing and increase i n f r i c t i o n r a t i o , a l l of which indicate the presence of a t h i n layer of f i n e r grained s o i l , probably a clayey s i l t . From t h i s depth on the pore pressures become negative, and whilst sleeve f r i c t i o n values are missing i n part, t h i s layer has been i d e n t i f i e d from s i t e experience as s i l t . At 9.93m the sounding was aborted due to encountering an impenetrable obstruction. Referring to p r o f i l e ANP9 shown i n Figure 10, the s o i l p r o f i l e from surface to 4.5m i s interpreted as f i l l sand, with a hardened surface crust. From 4.5m to 7.5m, bearing reduces, f r i c t i o n increases, and the pore pressures fluctuate both to the pos i t i v e and negative of hydrostatic. Such behaviour was found to be c h a r a c t e r i s t i c of the material underlying the f i l l sand, and was i d e n t i f i e d as primarily s i l t with sandy and clayey layers. The s i l t i s presumed to have been deposited on the bed of the Fraser River. The negative pore pressures are believed to be a consequence of the pore pressure sensor being located d i r e c t l y behind the cone t i p . As the cone t i p pushes through the soft s i l t the f a i l u r e mode causes generation of negative pore pressures which are quickly dissipated by the sand layers. From 7.5m to the end of the sounding at 14.77m pore pressures return to hydrostatic and the s o i l i s interpreted 51 as naturally deposited Fraser River Sand, which i s s i l t y i n part. The cross-section, Figure 11, demonstrates c l e a r l y how the thickness of sand f i l l increases to the east of the research s i t e . The straight comparison of cone resistance p r o f i l e s before and af t e r treatment with the Phoenix equipment for the e a r l i e r treatment i n the f i l l sand i s shown i n Figure 12. The same comparison of p r o f i l e s ANP9 and ANP15 for UBC monitored t e s t s i n the Fraser River Sand i s presented i n Figure 13. As mentioned above the 'after' p r o f i l e s constitute those demonstrating the maximum increase i n cone resistance. These were obtained from conducting the cone t e s t at the s i t e of a Phoenix probe hole. The increase i n cone resistance i s dramatic f o r both s o i l types. A f i v e - f o l d increase i n cone resistance was observed over the depth of treatment f o r the loose sand f i l l , whilst an increase i n excess of 100% was seen i n the Fraser River Sand. Maximum s o i l improvement was achieved to within lm depth of the t i p of the probe, with improvement decreasing as the ultimate probe-tip depth was approached. The depth of improvement therefore coincided with the depth reached by the toe of the drain unit. No improvement could be detected at depths i n excess of the ultimate depth penetrated by the t i p of the probe. Figure 11 Section Through Research Site Showing S o i l Layers 53 Figure 12 Comparison of Cone Penetrometer Soundings Performed i n Hydraulically Placed F i l l Sand Before and After Treatment with Phoenix Densification Equipment. 54 COJC BEARING Qc (bar) 15 30* . . . . . . . . . Figure 13 Comparison of Cone Penetrometer Soundings Performed i n Natural Fraser River Sands Before and A f t e r Treatment with Phoenix Densification Equipment. 55 The cone resistance i s low i n the upper sections of the post-treatment p r o f i l e s since the penetration tests were performed at s i t e s of Phoenix probe holes. No attempt was made to densify the upper section of bore, which generally remained open immediately a f t e r treatment. Soon a f t e r treatment the bore became unstable and collapsed, f i l l i n g with uncompacted b a c k f i l l . At probe locations the s i l t layer became p a r t i a l l y replaced by sand f i l l f a l l i n g from above, leading to an increased cone resistance at these depths. In the case of probe #15, investigated by cone t e s t ANP19, i t appears that a block of s i l t was able to f a l l into the lower section of the bore and mix with the sand. This shows there may be s i g n i f i c a n t mixing of s o i l s from d i f f e r e n t depths within the bore. Cone te s t s performed adjacent to Phoenix probe holes showed the process to be incapable of increasing cone resistance within the s i l t . In addition the v i b r a t i n g process had the e f f e c t of reducing the cone resistance i n the hardened surface crust. The uniformity of the sand a f t e r treatment was considerably greater when d e n s i f i c a t i o n was performed i n the sand f i l l material than i n the Fraser River Sand. The lack of s o i l uniformity i n the compacted Fraser River Sand i s attributed to occasional starvation of b a c k f i l l at the t i p , and to the inhomogeneity of the o r i g i n a l Fraser River Sand deposits. 56 The r e s u l t s of the pre and post-treatment f l a t dilatometer soundings are shown i n Figures 14 and 15. As anticipated the treatment causes increased values of pressure readings and thrust to be recorded. With one notable exception the values of Marchetti*s (1980) intermediate s o i l parameters increase also. The dilatometer modulus E D shows a twofold increase i n s t i f f n e s s for the improved sand. The horizontal stress index K D increases s l i g h t l y , perhaps r e f l e c t i n g increased l a t e r a l stress. I t i s int e r e s t i n g that the material index parameter I D remains quite constant before and a f t e r treatment except i n the zones where sand f i l l replaced s i l t . This indicates what a powerful s o i l type, indicator the I D parameter i s , proving to c o r r e c t l y i d e n t i f y the s o i l type independently of possible changes to sand density, modulus and stress conditions brought about by the Phoenix equipment. Whilst the p r o f i l e lacks the d e t a i l and continuity of the cone traces, the s o i l types indicated are i n good agreement with nearby cone p r o f i l e ANP9. Po. Pi (bars) Thrust (kN) lo 0 20 40 0 50 0.1 1 E D (bars) 500 1000 Location : Pre—trial Filename : ANP01.DAT Test Dote : 24/09/88 U. B. C. In Situ Testing Figure 14 F l a t Dilatometer P r o f i l e ANPD1 Before Treatment With Phoenix Densification Equipment. Po. Pi (bars) Thrust (kN) l D 0 20 40 0 50 0.1 1 10 0 ED (bars) 5 0 0 1000 m 0) E D_ UJ Q i 0 — 1 -2-3-4 - ]_ 5-6 -1 \ \ ^ 1 % 7- 5 8- \ > < 9 -1 1 1 1 J « I 1 ( 10- ) % \ \ \ 1 1 1 11 - 1 \ f 12-f / 1 < 1 \ 1 3 -1 4 -1 5 - 1 Or Locction : At Phoenix Probe Hole Filename : ANPD2.DAT Test Dote : 27/01/89 U. B. C. In Situ Test ing Figure 15 F l a t Dilatometer P r o f i l e ANPD2 Af t e r Treatment With Phoenix Densification Equipment. 59 5.2 Relative Density Recent research has shown that the s t r e s s - s t r a i n and strength c h a r a c t e r i s t i c s of a cohesionless s o i l are too complex to be represented only by the r e l a t i v e density of the s o i l . There has been much discussion on the d i f f i c u l t i e s of uniquely determining the maximum and minimum sand densities for c a l c u l a t i o n of r e l a t i v e density. Recent work with cone penetrometers i n large c a l i b r a t i o n chambers has attempted to develop relationships between cone bearing, e f f e c t i v e stress and r e l a t i v e density. Although no unique relationship e x i s t s between these parameters, useful relationships have been derived i f sand compressibility i s taken into account and i f cone bearing i s correlated with the i n s i t u horizontal e f f e c t i v e stress. One such relat i o n s h i p given by Baldi et a l . (1982) i s shown i n Figure 16. This r e l a t i o n s h i p applies to normally consolidated, uncemented and unaged quartz sands, of moderate compressibility. The r e l a t i o n s h i p can be applied also to overconsolidated sands i f the i n s i t u horizontal stress i s used instead of the v e r t i c a l s t ress. I t i s considered that the sands found at the Annacis North Pier s i t e are s i m i l a r i n nature to the T i c i n o t e s t sands from which the relationships of Baldi et a l . (1982) were developed, and the relationships are meaningful for the sands i n question. Figure 17 shows the change i n r e l a t i v e density of the shallow, h y d r a u l i c a l l y placed f i l l sand before and a f t e r treatment with the Phoenix equipment. T y p i c a l l y before 60 Figure 16 Relative Density Relationship for Uncemented and Unaged Quartz Sands (adapted from Baldi et a l . 1982) 61 10 RELATIVE DENSITY (*) 20 30 40 50 60 70 80 90 100 cn CD CD E LL LJ O 5-10--a y * / 1 y 1 I i < 1 i • r i 1 g E s : g ; g : g , J 3. • ^ — i *"« ^ • « BEFORE TREATMENT o AFTER TREATMENT ( t 5 • cr h -a t a — t y i (ANP1) PE6) fc, F x o g UJ o Figure 17 Comparison of Relative Densities From CPT Before and After Treatment with Phoenix Densification Equipment for Hydraulically Placed F i l l Sand. 62 treatment the sand f i l l density i s estimated at 45-55%. The sand density following treatment shows a substantial increase to 85-90% r e l a t i v e density, showing how e f f e c t i v e the Phoenix equipment can be. Admittedly the 'after' p r o f i l e has been generated from the cone p r o f i l e showing the greatest increase i n cone bearing achieved at the s i t e . Since no account has been made of possible increases i n horizontal stress brought about by the d e n s i f i c a t i o n process, the r e l a t i v e density so evaluated represents t r u l y an upper bound value. Figure 18 shows the change i n r e l a t i v e density caused by the Phoenix equipment i n t r e a t i n g the natural Fraser River Sand. Prior to treatment the sand i s consistently estimated at 65% r e l a t i v e density. Subsequent to treatment the r e l a t i v e density improves to 85-90%. Again, the 'after' p r o f i l e was derived from the one i n which the greatest increase i n cone bearing was observed, and so the r e s u l t s obtained are again an upper bound. For both of the sands i n which d e n s i f i c a t i o n was performed, the highest r e l a t i v e density achieved by the Phoenix compaction system was 85-90%. Such a state of compaction appears to be achievable independently of the v e r t i c a l e f f e c t i v e stress pertaining and also independently of the i n i t i a l s t a r t i n g density. 63 10 RELATIVE DENSITY (s) 20 30 40 50 60 70 80 —I I I 30 _ L 90 100 BEFORE TREATMENT (ANP9) AFTER TREATMENT (ANP 15) Figure 18 Comparison of Relative Densities From CPT Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands. 64 5.3 Shear Resistance Theories correlating the drained resistance of sand with cone penetration resistance are either based on bearing capacity or on cavity expansion theory. The cavity expansion approach i s complex in i t s requirement for shear strength and compressibility input data and i t s analysis. The two main parameters which control penetration resistance i n sands are shear strength and compressibility. Since the variation of compressibility i n most natural sands i s small, the shear strength has more influence on cone resistance than compressibility. For t h i s reason, the bearing capacity theories, which cannot account for s o i l compressibility are able to offer reasonable predictions of f r i c t i o n angle. From a review of c a l i b r a t i o n chamber and t r i a x i a l test results, Robertson and Campanella (1983) compared the various theoretical relationships available, noting whether such relationships tended to under or overestimate f r i c t i o n angle. Following t h i s work they were able to propose an average relationship which has been reduced to the form shown in Figure 19. Again the relationship i s applicable to moderately compressible, normally consolidated, unaged and uncemented quartz sands. This relationship has been used to estimate f r i c t i o n angles from the cone penetration tests performed at the Annacis s i t e . 65 Figure 19 Relationship Between Cone Bearing and F r i c t i o n Angle for Uncemented and Unaged Quartz Sands (After Robertson and Campanella, 1983). 66 Figure 20 shows the var i a t i o n of f r i c t i o n angle with depth, both before and after d e n s i f i c a t i o n , for improvement performed i n the hydraulically placed sand f i l l . Before treatment, f r i c t i o n angles of the sand f i l l are t y p i c a l l y estimated i n the range 36-40°. Subsequent to treatment with the Phoenix equipment the f r i c t i o n angle r i s e s to 44-46°, an increase of up to 10°. Figure 21 shows the same rel a t i o n s h i p for the Fraser River Sands before and after d e n s i f i c a t i o n . Before the treatment, f r i c t i o n angles were of the order of 40-42°. Densification with the Phoenix equipment was able to increase the f r i c t i o n values up to 44-46°, an increase of up to 6°. Once again, the 'after 1 p r o f i l e s have been generated from the cone penetrometer p r o f i l e s which are considered to demonstrate the best improvement achieved i n each of the respective s o i l p r o f i l e s at the s i t e . As with r e l a t i v e density, no account has been taken of possible increases i n horizontal stress brought about by the d e n s i f i c a t i o n process, so the f r i c t i o n angles so evaluated also constitute upper bound values. Peak f r i c t i o n angles were estimated also from the dilatometer soundings conducted. Sounding ANPD1 was performed before treatment whilst sounding ANPD2 was performed at the centre of a Phoenix probe hole. The data reduction programme supplied with the dilatometer uses the bearing capacity equation of Durgonoglu and Mit c h e l l (1975) 67 FRICTION ANGLE (degrees) 30 32 34 36 38 40 42 44 46 48 50 to CD •+-> CD E IE a. L d Q 10 — — -o •— 8 t s 8 \ o 0 • • 1K~--CLD • BEFORE TREATMENT (ANP1) o AFTER TREATMENT (PE6) fc | X UJ ° 5 Ul O Figure 20 Comparison of F r i c t i o n Angles From CPT Before and After Treatment with Phoenix Densification Equipment for Hydraulically Placed F i l l Sand. 68 FRICTION ANGLE (degrees) 30 32 34 36 38 40 42 44 46 48 50 5 -E CL LU Q 10 15 . I . ! < I < I < I < I . I . I . I . • BEFORE TREATMENT (ANP9) n AFTER TREATMENT (ANP 15) D -43 J-g IS- _ g — * f J ; s 3 2 a. O UJ >< z ui o X a. 51 !i ui 1 U l C9 Figure 21 Comparison of F r i c t i o n Angles From CPT Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands. Figure 22 Comparison of F r i c t i o n Angles From DMT Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands. 70 to calculate f r i c t i o n angles. Figure 22 compares the f r i c t i o n angles calculated from the dilatometer soundings, before and after Phoenix treatment. The comparison relates on]y to compaction i n the natural Fraser River Sand deposit. The f r i c t i o n angles both before and afte r treatment are similar to and reinforce those deduced from the cone penetration tests. According to the interpretation methods adopted, the Phoenix equipment i s capable of increasing the peak f r i c t i o n angle of the s o i l s at the s i t e up to a maximum of 44-46°. Again the f i n a l f r i c t i o n angle achievable i s independent of the i n i t i a l states of stress and strength. 5.4 Modulus and Compressibility As previously mentioned the cone resistance i n sand i s a function of both shear resistance and compressibility. Despite t h i s , various empirical correlations have been established d i r e c t l y relating cone resistance to the various moduli. Many relationships employ a straightforward multiplying factor. Since s o i l i s not li n e a r e l a s t i c and modulus varies with both stress and s t r a i n l e v e l , such a simple approach must be inadequate. Such relationships are available for the evaluation of an equivalent Young's modulus, constrained modulus, and shear modulus. Naturally the choice of values for the respective multiplying factors i s a l l important. Preferably the factors should be derived 71 from l o c a l experience and calibrated against superior test methods. Since the interpretations of moduli from cone resistance do nothing more than scale up the cone bearing p r o f i l e s , t h e i r application to a before and afte r vibrocompaction evaluation i s of l i t t l e i n t e r e s t . The evaluation of s o i l moduli in the following section i s therefore based on data other than the cone penetration resistance. S p e c i f i c a l l y , the constrained modulus was evaluated from the f l a t dilatometer t e s t , and the shear modulus was evaluated from the seismic cone t e s t . 5.4.1 Constrained Modulus The one dimensional or constrained modulus was evaluated from the f l a t dilatometer soundings by using a version of the data reduction programme supplied with the dilatometer apparatus. I t uses an empirical c o r r e l a t i o n based on Marchetti (1980). The p r o f i l e s of constrained modulus obtained from the dilatometer soundings before and a f t e r treatment with the Phoenix equipment can be seen i n Figure 23. Data i s only available for the Fraser River Sand. During cone te s t s , the maximum cone response was observed at the location of a Phoenix probe hole, and decreased with distance from the probe. With the dilatometer, one might anticipate a s i m i l a r decrease of improved s o i l response with increasing distance Figure 23 Comparison of Constrained Modulus From DMT Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands. 73 from a Phoenix probe. As a consequence, p r o f i l e ANPD2, located at a Phoenix probe location cannot be considered representative of post treatment s o i l conditions across the s i t e , but i t does serve to demonstrate the potential improvement achievable with the Phoenix d e n s i f i c a t i o n system. The post treatment p r o f i l e shows a very s i g n i f i c a n t increase i n constrained modulus i n the region of the s i l t layer. This i s not believed to r e f l e c t an increase i n the strength of the s i l t but to be due to replacement of s i l t by f i l l sand from higher i n the bore. This has subsequently been densified by the Phoenix probe. From 8.5m on, within the Fraser River Sand, there i s an increase i n constrained modulus of over 100%. 5.4.2 Shear Modulus The small s t r a i n shear modulus, GMAX ** a s been determined from the shear wave v e l o c i t i e s measured during the seismic piezocone t e s t . Tests were performed before and a f t e r treatment with the Phoenix equipment fo r the work conducted i n the Fraser River Sands. The method has been described b r i e f l y i n section 4.2.5. The s o i l densities required for the c a l c u l a t i o n of shear modulus were estimated from the dilatometer t e s t s . 74 The s e i s m i c piezocone t e s t performed a f t e r d e n s i f i c a t i o n treatment was l o c a t e d over the 1.5m spaced t r i a n g l e of Phoenix probes, as t h i s was c o n s i d e r e d the most favourable p o s i t i o n a v a i l a b l e t o d e t e c t changes i n shear wave v e l o c i t y . S i n c e the shear wave source ( r e a r t r u c k pad) was s i t u a t e d 2.1m from the cone h o l e , i t had t o be accepted t h a t p a r t of the wave t r a v e l path would l i e o u t s i d e the 1.5m spaced t r i a n g l e o f Phoenix probes. T h i s may have c o n t r i b u t e d to the r e c o r d i n g of slower t r a v e l times than might otherwise have been achieved had the t e s t been performed over an area where b l a n k e t coverage of d e n s i f i c a t i o n had been performed. The p r o f i l e s o f maximum shear modulus b e f o r e and a f t e r treatment w i t h the Phoenix equipment a re d e p i c t e d i n F i g u r e 24. The r e s u l t s show e f f e c t i v e l y no d i f f e r e n c e i n GMAX f o l l o w i n g treatment. T h i s i s an unexpected r e s u l t s i n c e one would have expected a GMAX i n c r e a s e t o accompany d e n s i f i c a t i o n . The i n a b i l i t y of the s e i s m i c piezocone t e s t t o d e t e c t changes i n GMAX due t o vibrocompaction treatment was a l s o found from a separate UBC t e s t programme which i n v e s t i g a t e d a F r a n k i T r i s t a r probe, a t a s i t e with s i m i l a r s o i l c o n d i t i o n s t o the Annacis North P i e r s i t e (Brown, 1989). From both i n v e s t i g a t i o n s i t would appear t h a t the se i s m i c t e s t i s i n s e n s i t i v e t o changes i n maximum shear modulus brought about by the vibrocompaction p r o c e s s . Figure 24 Comparison of Maximum Shear Modulus From SCPTU Before and After Treatment with Phoenix Densification Equipment for Fraser River Sands. 7 6 5.5 In S i t u S t r e s s Conditions I t i s a n t i c i p a t e d that K Q c o n d i t i o n s w i l l p r e v a i l i n the r e c e n t l y placed f i l l sand p r i o r to d e n s i f i c a t i o n treatment. One might a l s o expect such c o n d i t i o n s i n the n a t u r a l l y deposited Fraser R i v e r Sands below, s i n c e they have not apparently undergone any s i g n i f i c a n t s t r e s s changes s i n c e d e p o s i t i o n . The s i g n i f i c a n t s urface settlement observed during o p e r a t i o n of the Phoenix equipment c l e a r l y i n d i c a t e s compaction and an 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 of the l o o s e s o i l below. An attempt to q u a n t i f y t h i s i n c r e a s e has been attempted i n S e c t i o n 5.2 above. However, the mechanism of the v i b r a t i n g equipment i s such t h a t l a r g e h o r i z o n t a l f o r c e s are imparted to the s o i l at depth, and i t seems reasonable to p o s t u l a t e t h a t these might l e a d t o some i n c r e a s e of i n s i t u h o r i z o n t a l s t r e s s e s . C a l i b r a t i o n chamber research has demonstrated the dependence of cone b e a r i n g i n sands on i n s i t u e f f e c t i v e s t r e s s e s , p a r t i c u l a r l y h o r i z o n t a l s t r e s s , as w e l l as r e l a t i v e d e n s i t y (Houlsby and Hitchman, 1988). An i n c r e a s e i n h o r i z o n t a l s t r e s s would, i f not taken i n t o c o n s i d e r a t i o n , l e a d t o overestimates of the improvement i n r e l a t i v e d e n s i t y and shear r e s i s t a n c e . Unfortunately, i t i s not p o s s i b l e to d i s t i n g u i s h the separate i n f l u e n c e s of r e l a t i v e d e n s i t y and h o r i z o n t a l s t r e s s from a cone p e n e t r a t i o n t e s t under drained c o n d i t i o n s . 77 Sometimes, a high sleeve f r i c t i o n can be in d i c a t i v e of high horizontal stress conditions. In Figure 25 sleeve f r i c t i o n values have been plotted against cone resistance for both unimproved and improved s o i l . The r a t i o between the two, that i s the f r i c t i o n r a t i o , remains f a i r l y constant for both unimproved and improved sand, although there appears to be a s l i g h t increase i n f r i c t i o n r a t i o at the highest cone bearings. The uniformity of the relationship indicates what a powerful s o i l type indicator the f r i c t i o n r a t i o i s , independent of sand density and s t i f f n e s s . The s l i g h t l y higher f r i c t i o n r a t i o at higher cone bearings might suggest increased l a t e r a l stress. Marchetti (1985) developed a method to determine K Q i n sands from f l a t dilatometer t e s t data. The computation i s b u i l t into the data reduction programme available with the dilatometer apparatus. Figure 26 demonstrates the evaluation of K Q f o r the two dilatometer soundings conducted. The data refers only to the Fraser River Sands. As anticipated, p r i o r to compaction treatment, the K Q value i n the sands averages about 0.5. Subsequent to treatment with the Phoenix equipment there i s an increase i n the densified sands and K Q has r i s e n to around 0.7. The increase i n K Q indicated within the s i l t i s attributed to the mixing of s o i l types. By combining the estimation of K Q and v e r t i c a l e f f e c t i v e stress provided by the DMT data reduction programme, a p r o f i l e of i n s i t u horizontal stress with depth has been generated. The horizontal stress p r o f i l e s before 78 F i g u r e 25 R e l a t i o n s h i p Between Cone Bea r i ng and F r i c t i o n S leeve Be fore and A f t e r Treatment With Phoenix D e n s i f i c a t i o n Equipment. 79 Figure 26 Comparison of K Q From DMT Before and After Treatment With Phoenix Densification Equipment. 80 and a f t e r treatment with the Phoenix equipment are compared in Figure 27. The upper regions of the post d e n s i f i c a t i o n p r o f i l e of horizontal stress are lower than before treatment since d e n s i f i c a t i o n was not attempted i n t h i s region and the Phoenix probe hole has merely f i l l e d with loose sand. Below 5m the p r o f i l e s show a marked increase i n horizontal stress. In part t h i s can be attributed to s i l t replacement by sand, but an increase i s c l e a r l y shown for the sands also. From 9m on the horizontal stress i s indicated to increase from about 70kPa up to 80kPa. The increase has been imparted by the h o r i z o n t a l l y v i b r a t i n g Phoenix equipment. Since the magnitude of the stress increase has been quantified, i t i s possible to separate the influences on cone bearing of increased r e l a t i v e density and horizontal stress. According to the relationship of Figure 16, the lOkPa increase of horizontal e f f e c t i v e stress would be responsible for an overestimation of r e l a t i v e density i n the region of 5%. On t h i s basis the post-treatment r e l a t i v e densities shown i n Figures 17 and 18 should be reduced by 5% over the range of treatment, whilst the f r i c t i o n angles of Figures 20 and 21 would be reduced by almost a f u l l degree. 81 1 5 Figure 27 Comparison of In Situ Horizontal Stress From DMT Before and After Treatment With Phoenix Densification Equipment. 82 5.6 Summary This section of the thesis has demonstrated the degree of improvement to s o i l parameters which i s possible by treatment with the Phoenix d e n s i f i c a t i o n equipment. In terms of r e l a t i v e density, improvements up to 85-90% are consistently achieved, independently of the i n i t i a l s t a r t i n g density and overburden stress. The maximum r e l a t i v e densities achievable should be reduced by 5% to take into consideration increases i n horizontal stress caused by the d e n s i f i c a t i o n process. The t e s t programme has demonstrated that the Phoenix treatment i s suited to fine, s i l t y sands, but should not be attempted i n s i l t . During the process, there i s an appreciable degree of mixing of s o i l types i n the v i c i n i t y of the bore. The f r i c t i o n r a t i o from a cone t e s t , and the material index from a f l a t dilatometer te s t are powerful s o i l type indicators which are independent of changes i n r e l a t i v e density, s t i f f n e s s , and stress conditions. The seismic piezocone test i s i n s e n s i t i v e to changes i n s o i l s t i f f n e s s induced by the vibrocompaction process. 83 6. TEST RESULTS This section of the thesis presents and discusses the res u l t s of the investigation into the parameters aff e c t i n g the performance of the Phoenix d e n s i f i c a t i o n equipment. As described i n Section 4.3, the Phoenix equipment f a i l e d to perform r e l i a b l y during the ANP test s e r i e s , the series performed s p e c i f i c a l l y for t h i s investigation. Consequently, the te s t data has been augmented with r e s u l t s obtained from the e a r l i e r t e s t series performed by Phoenix Ltd.. As far as the re s u l t s presented i n t h i s Chapter are concerned, s o i l conditions were monitored exclusively by the piezocone penetrometer t e s t . 6.1 Evaluation of a Single Compaction Probe The extent of the range of influence of a single compaction probe has been explored by performing cone penetration t e s t s at various distances from the probe. I t was found that cone soundings conducted over locations of de n s i f i c a t i o n probes tended to y i e l d the largest increases of penetration resistance. Comparisons of cone resistance before and a f t e r treatment have been presented i n Figures 12 and 13, for the sand f i l l and Fraser River Sand respectively. These demonstrated the large potential increases i n cone resistance following d e n s i f i c a t i o n treatment. 84 Pertinent data from the o r i g i n a l Phoenix f i e l d t r i a l s , performed i n 1987, and from the UBC monitored t r i a l s has been selected to investigate the e f f e c t of a single d e n s i f i c a t i o n probe. Data has only been included where i t i s clear there i s no interaction from surrounding de n s i f i c a t i o n probes so that only the influence of a single probe i s considered. The v a r i a t i o n of cone resistance with distance from a single probe hole for the two s o i l conditions i s shown i n Figure 28. Data points r e f e r to calculated mean cone bearings over the ranges of improved s o i l . For the o r i g i n a l Phoenix f i e l d t r i a l s , the cone bearing has been averaged over the depth i n t e r v a l 2.0m to 6.0m. For the UBC monitored t r i a l s the bearing represents the mean cone bearing over the depth range 6.0m to 10.5m. To take account of the d i f f e r e n t v e r t i c a l stresses at these depths the cone bearings have been normalized by the cone bearing before treatment. The res u l t s show that the r e s u l t i n g sand density i s greatest i n the close v i c i n i t y of the probe and decreases with increasing distance from the probe. The findings are i n general agreement with a s i m i l a r study by D'Appolonia (1953) i n his investigation of a v i b r o f l o t . The rate of decrease of cone bearing i s f i t t e d approximately by the exponential curves shown. Higher values of normalized cone bearing are exhibited by the tests i n the f i l l sand, r e f l e c t i n g the lower sand densities p r i o r to compaction. The res u l t s of the work performed within the Fraser River Sand suggest that the compaction treatment can act u a l l y reduce the cone resistance 85 CD 5 — z -cn < -1 I LU _ k co 4 4 k LU o o _ 3 — Q -LU N < 2 -or o z : 0 0.0 •Extent of Phoenix probe A P U M P E D S A N D FILL DATA F R A S E R RIVER S A N D DATA S A N D FILL F R A S E R RIVER S A N D i i i i i i i I i i i i i i i i i I i i i i i i i I I I I I I I I 0.5 1.0 1.5 2.0 DISTANCE FROM PHOENIX PROBE (metres) Figure 28 Variation i n Cone Resistance Around a Single Phoenix Probe Hole, Normalized by Cone Resistance Before Treatment. 86 at distances i n excess of lm from the probe. For both s o i l conditions, there i s no influence of a single compaction probe outside of a radius of 1.5m from the probe centre. In Figure 29 the normalized cone data of the previous figure has been multiplied by the r e l a t i v e density, estimated from pre-treatment cone t e s t s . The best f i t exponential l i n e s for the data of the two s o i l conditions collapse to a single l i n e which has the form: q„, Rd = 1.87 e ° ' 9 D where q c , i s the cone resistance following treatment q Q i s the cone resistance before treatment Rd i s the r e l a t i v e density before treatment D i s distance from the Phoenix probe. Working from just a pre-treatment cone resistance, the relationship can be used to estimate the l i k e l y cone bearing increase around a single compaction probe. Since the relationship has been developed from only s o i l s at the Annacis North Pier s i t e , and at two depths, i t s application in other s o i l s should be used with caution. Scatter i n the data i s also appreciable but i s p a r t l y due to poor equipment performance and l a t e r a l s o i l type variations at the s i t e as well as mixing of d i f f e r e n t s o i l layers during treatment. 87 CO z Ld O U > -Extent of Phoenix probe PUMPED SAND FILL DATA FRASER RIVER SAND DATA i I i i i i i i i i i I i i i i i i i i i I i i i i i i i i i 0.5 1.0 1.5 2.0 DISTANCE FROM PHOENIX PROBE (metres) Figure 29 Proposed Relationship to Determine the Variation of F i n a l Cone Bearing with Distance from Phoenix Probe Hole. 88 6.2 Investigation of Variable Parameters 6.2.1 E f f e c t of Spacing and Pattern In densifying a large area i t i s important to select the most e f f i c i e n t pattern of d e n s i f i c a t i o n probes and to space probes co r r e c t l y to achieve required s o i l densities. The triangular pattern i s the most e f f i c i e n t pattern, whilst square patterns may require up to 8% more probes to achieve the same minimum densities (Brown, 1977). To investigate the e f f e c t of probe spacing and pattern on the Phoenix process, programmes of tr i a n g u l a r probe configurations were performed. For the Fraser River Sand, triangular spacings of 1.5m, 2.5m, 3.5m and 4.5m were conducted. Cone tests were performed at the centroids of the 1.5m and 2.5m configurations. The r e s u l t s are presented i n Figure 30. The spacing of probes for the UBC t e s t schedule are interesting. The cone test performed at the centroid of the closest spacing of 1.5m demonstrates a very s i g n i f i c a n t improvement, i n excess of 120% of the i n i t i a l cone resistance. The improvement i s considerably i n excess of what would be expected at an equivalent distance from a single probe, Figure 31. There i s therefore s i g n i f i c a n t i nteraction and increased compaction between probes at t h i s spacing. At the next largest spacing attempted, 2.5m, i t was found that the cone resistance at the centroid of the probes was s i g n i f i c a n t l y lower following Phoenix treatment than before treatment. The development of a zone of loose sand at 89 CONE BEARING Qc (bar) 30D CO Q) L -P Ql E Q_ LU Q LEGEND 1.5m Spacing 2.5m Spacing Pre—trial Figure 30 Influence of Spacing of Phoenix Machine Probes on Cone Resistance for Fraser River Sand. 90 CONE BEARING Qc (bar) (I) QI L -P QI E X I— Q_ LU Q 300 I5i 20 0.86m FROM THREE PROBES 2 a. O Ul X s o X a. & Si C9 0.85m FROM SINGLE PROBE Figure 31 Influence of Pattern of Phoenix Machine Probes on Cone Resistance for Fraser River Sand. 91 the centre of the 2.5m centroid i s believed to be due to a tendency for sand grains to move i n the di r e c t i o n of the Phoenix probe as compaction and settlement occurs i n the v i c i n i t y of the probe. I f the vibrating action i s i n s u f f i c i e n t to develop compacting forces at the centroid of the probes, a loose zone can develop (Brown, 1977). The situa t i o n i s made worse i f there i s a shortage of b a c k f i l l s o i l available at the t i p to make up for the loss i n volume caused by compacting s o i l (Brown, 1977). Such may have been the case for the tests conducted i n the Fraser River Sands, since they have an overlying s i l t cap. Finding a loose zone at the centre of a triangular compaction configuration i s consistent with the investigations of Section 6.1 above, where i t was found that s o i l may be loosened i n a zone approximately 1.0 to 1.5m from a single compaction probe. The data of Figure 32 i s taken from the F series of cone holes performed by Phoenix i n 1987, and shows the effe c t i n the f i l l sand of changing the spacing between den s i f i c a t i o n probes. The cone soundings were performed at the centroids of tr i a n g l e s of compaction probes spaced at 1.8m, 2.1m, 2.4m, and 3.0m. The 1.8m spacing demonstrates an increase i n excess of 100% over the i n i t i a l cone resistance. For probe spacings of 2.1m and greater, only s l i g h t or no improvement could be detected. There was no reduction i n cone resistance at larger probe spacings as was observed for the Fraser River Sands. I t i s postulated that sand f i l l from higher in the bore was able to migrate downwards. Since an 92 CONE BEARING Qc (bar) Figure 32 Influence of Spacing of Phoenix Machine Probes on Cone Resistance for Hydraulically Placed F i l l Sand. 93 adequate supply of b a c k f i l l was maintained, a high state of compaction was achieved. 6.2.2 Influence of Frequency To maximize the input of v i b r a t i o n a l energy into the s o i l the frequency of vibrations should be optimized. Increasing the input energy to the s o i l should have the e f f e c t of enlarging the zone of influence of the probe. P r i o r to the f i e l d t r i a l s i t was believed that the frequency of operation of the Phoenix equipment would be controllable by varying the pressure of a i r supply to the vi b r a t i n g motor unit. During f i e l d t e sts the frequency of v i b r a t i o n of the probe i n a i r was monitored from a piezoceramic bender element mounted d i r e c t l y on the v i b r a t i n g u n i t . The bender output was observed on an oscilloscope. The minimum a i r supply required to turn over the motor unit was around 80 p s i . The motor would not run smoothly at le s s than 100 p s i . At pressures up to the maximum availa b l e of 120 p s i , no v a r i a t i o n of input supply pressure could e f f e c t i v e l y control the frequency of v i b r a t i o n of the Phoenix Machine. The nominal and only operating frequency available from the v i b r a t i n g motor unit was around 25Hz, and t h i s was most comfortably achieved with an a i r supply pressure of 100 p s i . Following t h i s discovery, the investigation into the e f f e c t of frequency on the process had to be abandoned. 94 6.2.3 E f f e c t of Time Spent Densifyina One aspect of the compaction process with an important economic consequence, and of inter e s t to Phoenix was to assess the influence of time spent ac t u a l l y densifying at a p a r t i c u l a r depth or location. Any given compaction project may c a l l f o r the execution of hundreds or even thousands of compaction probes. Clearly, to develop a programme of optimum e f f i c i e n c y one must be aware how the ground improvement develops with time spent i n treatment. A series of probes was conducted which used d i f f e r e n t durations of compaction. The times investigated were 2, 4, and 6 minutes/metre, over the depth at which improvement was sought. The compaction time favoured and used routinely by Phoenix had been 6 minutes/metre. The development of improvement f o r the d i f f e r e n t cases was checked by performing cone t e s t s at 0.3m and 0.6m from the Phoenix probe holes. The drainage element of the Phoenix probe f a i l e d to operate e f f e c t i v e l y f o r each of the probe holes performed for t h i s series, so that s o i l improvement was not as s i g n i f i c a n t as hoped for. The r e s u l t s of the investigation into the e f f e c t of duration of d e n s i f i c a t i o n are presented i n Figure 33. The data points represent the averaged cone bearings over the depth range 9.5m to 10.5m. Data from the f u l l range of treatment depth could not be included i n the analysis due to data anomalies i n the cone resistance p r o f i l e s . Even when the data has been c a r e f u l l y selected to omit anomalies, the r e s u l t s are not as expected 95 2.00 co i_ o 150 O Z £ 100 LU m LU Z O O 50 H 0 0-0 .3m FROM P R O B E _ 0 .6m FROM © P R O B E Data points represent the m e a n cone res is tance over the depth interval 9 .5 to 1 0 . 5 m 0 2 4 6 DENSIFYING TIME (minutes/metre) 8 Figure 33 Influence of Time Spent Densifying on Cone Resistance f o r Fraser River Sand. 96 nor do they show any clear trend. Whilst the cone resistance at 0.6m from the probe increases s l i g h t l y with increasing time spent densifying, i t decreases with time at 0.3m from the probe. One explanation for the re s u l t s derives from observation that the cone p r o f i l e s for t h i s part of the investigation are rather anomalous. I t i s postulated that the overlying s i l t layer, thicker at t h i s location of the s i t e than at any other location, formed an arch over compacting sand below. As the sand continued to compact, a deficiency of b a c k f i l l at the t i p reduced the a b i l i t y of the probe to further compact the s o i l . This led to the exertion of a much reduced overburden stress acting on the sand during compaction. I t i s known that the vibrocompaction process i s i n e f f e c t i v e i f performed i n s o i l s where there i s no overburden stress, for instance i n near surface s o i l s . As the treatment process continued, s i l t may have collapsed into the bore leading d i r e c t l y to development of poor penetration resistances within the bore. As the duration of de n s i f i c a t i o n operations was varied, so did the degree of sand compaction, and so too did the extent of development of the s i l t arch. In t h i s way, the changing conditions i n the bore led to the apparently anomalous r e s u l t s for the time t r i a l . 6.2.4 Ef f e c t of Time Following Densification During the UBC monitored t r i a l s a programme was run to investigate whether the strength gain process was time 97 dependent. S o i l strength was measured using cone penetration tests at centres of compaction at pa r t i c u l a r time periods following s o i l densification. Compaction point centres were chosen for monitoring since i t was considered that these would y i e l d the most repeatable conditions. Since the Phoenix equipment performed e r r a t i c a l l y , the repeatability of the compaction process was brought into question. In addition, the number of probe holes available for testing was reduced. Further penetration tests at the s i t e s of previously tested centres are not r e l i a b l e due to the proximity and influence of any previous tests. The available results are shown in Figure 34, where the data points have been generated from the mean cone bearing calculated over the depth interval from 6.0m to 10.5m. The data i s not conclusive but suggests that the strength gain for the Phoenix process develops immediately or during the f i r s t day following compaction. Further improvement with time cannot be confirmed with the data available at t h i s s i t e . The results obtained are i n contrast to the extensive evidence of Mitchell and Solymar (1984) where i t was found that penetration resistance increased with time, and followed an i n i t i a l reduction of cone resistance d i r e c t l y a f t e r densification treatment. No data i s available to demonstrate the effects of time for the test series performed without the drainage element, nor for the PH, or PE series of tests performed by Phoenix Limited. 98 200 % 150 CD O z ^ 100 LU CQ LU Z o 50 o Data points represent the mean cone resistance measured at or close to Phoenix compaction probes over the depth interval 6.0 to 10.5m. 0 ~|—I—I—i—I—i—i—i—I—i—|—i—I—i—i—i—i—i—I—i—|—I—i—i—i—i—I—i—r 0 10 20 TIME ELAPSED (Days) 30 Figure 34 Influence of Time Following Densification on Cone Resistance for Fraser River Sand. 99 6.3 Influence of Simultaneous Drainage To determine the significance of the drainage e f f e c t on the Phoenix process, sections of the t r i a l s were conducted i d e n t i c a l l y , but with and without the drainage element. This was a most important aspect of the process, and one on which the e a r l i e r t r i a l s of Phoenix had not provided r e l i a b l e information. To run the Phoenix equipment i n a v i b r a t i o n only mode was simply a matter to leave out the drainage element when making up the equipment s t r i n g . The absence of the drainage u n i t appeared not to a l t e r the operation of the vibratory equipment i n any way. S t r i k i n g evidence demonstrating the important influence of pumping water during compaction comes from the investigations of single Phoenix probes, performed with and without the drainage equipment. The r e s u l t s are shown i n Figure 35, where the mean cone bearings calculated for the depth i n t e r v a l 6.0m to 10.5m are plotted against distance from the centre of the probe hole. Both cases demonstrate the approximate exponential decrease of cone bearing with increasing distance. Repeatedly the cone resistance i s s i g n i f i c a n t l y higher around the probe hole performed with the drainage element than for the probe hole performed without drainage. The cone bearing with the drainage equipment i s up to double the case without drainage, i n the close v i c i n i t y of the probe hole. The e f f e c t decreases with 200 Data points represent the mean cone resistance 0 over the depth interval 6.0 to 10.5m D I S T A N C E F R O M P H O E N I X P R O B E IN M E T R E S ' Figure 35 Influence of Drainage Element on Cone Resistance for Fraser River Sand. 101 increasing distance from the probe hole as the compaction influence reduces. A second example depicting the benefit of the drainage element was intended to come from the triangular spacing investigation. However, the drainage equipment f a i l e d to function properly during the performance of the 1.5m spaced t r i a n g l e , hence the triangular series without drainage was conducted at a 2.5m spacing i n order to match the 2.5m spacing with drainage. As was l a t e r revealed by the investigation into spacing effects, the 2.5m spacing was too large to permit any improvement at the centres of such t r i a n g l e s . The decrease of cone resistance measured at the centre of the 2.5m spaced probes with drainage was duplicated f o r the 2.5m spaced probes performed without drainage, and no difference between the two cases could be detected. 6.4 Ground Vibration Monitoring Following on from the investigation of Section 6.2.3, where the development of s o i l compaction increasing time of d e n s i f i c a t i o n was studied, the next objective would be to measure the degree of compaction as the treatment proceeded. Various methods to achieve t h i s have been described i n Chapter 2. During the ANP series of tests, attempts were made to monitor compaction progress as i t occurred. In the f i r s t 102 attempt the t i p of the Phoenix probe was instrumented with a Geospace v e l o c i t y transducer. The transducer was cemented into a housing d r i l l e d i n the body of the vi b r a t i n g t i p and cabled through the annulus of the d r i l l pipes to surface. The transducer was a calibrated v e l o c i t y device, whose output could be recorded on a d i g i t a l oscilloscope and manipulated to y i e l d horizontal probe acceleration, displacement and v e l o c i t y . Unfortunately, despite the utmost care exercised by the operators of the Phoenix equipment, the connecting cable was severed on making up connections of the d r i l l pipes. Every repair was followed by another severance and eventually the idea of receiving v i b r a t i o n measurements from the t i p mounted device had to be abandoned. As an alternative monitoring system to check compaction performance, an attempt was made using a surface monitoring technique. This consisted of embedding geophones i n the surface s o i l at a predetermined distance from the Phoenix probe hole. The technique avoids the d i f f i c u l t i e s of t i p instrumentation, but data interpretation becomes more d i f f i c u l t than with the t i p mounted device. One d i f f i c u l t y arises due to the f a c t that the vibratory process loosens the surface layer whilst compacting at depth. Consequently i t can be d i f f i c u l t to determine how compaction i s proceeding. For the surface monitoring work performed at the Annacis North Pier s i t e , i t was found that the vibrations measured by the geophones were not coming d i r e c t l y from the 103 probe but, rather were surface waves propagating from the outriggers of the d r i l l r i g . Since there was no i s o l a t i o n system between the Phoenix probe and the connecting d r i l l pipes, the vibrations passed up the d r i l l pipes and caused a strong v i b r a t i o n of the d r i l l r i g . Consequently the measurements could not be used to monitor d e n s i f i c a t i o n . The major use of the geophones proved to be for the d i r e c t measurement of frequency of probe operation, described i n Section 6.2.2 above. 6.5 Comparison With Other Vibrocompaction Systems The compaction capacity and behaviour of the Phoenix system have been demonstrated i n the preceding sections. To properly assess the benefits of the instrument i t has to be compared r e l a t i v e to other vibrocompaction equipment available. The geotechnical l i t e r a t u r e has been examined for case h i s t o r i e s investigating vibrocompaction systems. In Figure 36, the data of three other authors has been compared with the Phoenix data. On the ordinate i s plotted the previously adopted quantity, the f i n a l cone bearing normalized f o r the i n i t i a l cone bearing multiplied by the i n i t i a l r e l a t i v e density. In t h i s way differences i n compaction depths and i n i t i a l densities may be taken into consideration. On the abscissa i s plotted the distance from the probe, normalized by the diameter of the probe. This i s important since the e f f e c t i v e sizes of probes considered d i f f e r by nearly an order of magnitude. Whilst the s i z e of 104 £ 4 CO D I S T A N C E F R O M P R O B E / DIAMETER O F P R O B E F i g u r e 36 A b i l i t y o f Phoenix Machine t o D e n s i f y S o i l Around a S i n g l e Compaction Probe Compared t o Other Equipment. v 105 the equipment i s taken 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 allowance f o r d i f f e r e n c e s of machine power output. Comparing s i m i l a r machines, the v i b r o f l o t of D'Appolonia (1953) f o r which data i s shown i n F i g u r e 36, developed a c e n t r i f u g a l f o r c e of 10 tons, compared t o only 2.3 tons f o r the Phoenix equipment. No such data 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), but i t i s assumed t o be of a t l e a s t the c a p a c i t y as t h a t of D'Appolonia. The v i b r a t o r atop the T r i s t a r probe developed a c e n t r i f u g a l f o r c e of up t o 1.13 MN (Massasch & Vanneste, 1988). F i g u r e 36 shows t h a t the nature o f the improvement a c h i e v a b l e with the Phoenix equipment i s of a d i f f e r e n t c h a r a c t e r t o t h a t a c h i e v a b l e with the systems which do not have the water pumping f a c i l i t y . The l a t t e r systems are abl e to cause s o i l improvement a t up to d i s t a n c e s equal t o about 3 probe diameters, whereas the Phoenix equipment i s capable of improving s o i l a t d i s t a n c e s o f up t o 6 or more probe diameters. In the r e g i o n c l o s e t o the probe i t s e l f , the degree of improvement of the Phoenix equipment f a l l s i n the middle of the range d i s p l a y e d by the c o n v e n t i o n a l systems, w h i l s t a t probe diameters i n excess o f 2 the Phoenix system o f f e r s i n c r e a s e d compaction over the co m p e t i t i o n . For the con v e n t i o n a l systems i t appears t h a t t h e r e i s l i t t l e improvement o u t s i d e o f a zone about 3 probe diameters i n s i z e . When the Phoenix system i s operated without the b e n e f i t o f drainage, the r e s u l t s are w i t h i n the range of s i m i l a r equipment, except i n the v i c i n i t y o f the probe where 106 poorer r e s u l t s were obtained. The advantage of the Phoenix seepage system over the conventional equipment i s most marked i n the region from 2 to 8 probe diameters, and that i f the sizes of the probes are taken into consideration, the Phoenix equipment constitutes a very e f f i c i e n t d e n s i f i c a t i o n system. Machine Diameter Frequency Spacing 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 Foster Terraprobe 0.76 15 0.9-2.4 1-3 Anderson 1974 Vibrorod 0.5 - 1.7 3 Saito, 1977 Mytilus 2.1 25 6.5 3 Davis et a l . , 1981 Vibro-wing 1.6 20 2.5 2 Massarsch & Broms,1983 Franki T r i s t a r 1.0 20 2.0 2 Massarsch & Vanneste,1988 Phoenix Machine 0.19 25 1.8 9 Present study Table I I I . Details of Various Vibrocompaction Systems Table III shows d e t a i l s of the major systems available for the deep compaction of s o i l s i n s i t u . To compare approximately the effectiveness of the various machines, the r a t i o of t y p i c a l probe spacing to probe diameter has been considered. Typical values of t h i s parameter for the v e r t i c a l l y v i b r a t i n g systems are i n the range of 1 to 3, 107 whilst the v i b r o f l o t attains values from 6 to 8. This r e f l e c t s well the widely held b e l i e f that the horizontally vibrating devices are f a r more e f f e c t i v e than the v e r t i c a l l y v i b r a t i n g probes. I f the spacing of 1.8m recommended from t h i s investigation i s adopted, the Phoenix Machine scores the highest spacing to diameter r a t i o of 9. This indicates that for i t s siz e , the Phoenix Machine must be considered the most e f f i c i e n t of the systems considered i n Table I I I . 6.6 Summary This Chapter of the thesis has presented the results of the investigation into the parameters influencing the performance of the Phoenix equipment. The e f f e c t of increased compaction has been shown to decrease approximately exponentially with increasing distance from a singl e compaction probe. No influence of the Phoenix probe was detected at distances i n excess of 1.5m. A relationship was developed to permit the prediction of the v a r i a t i o n of compaction with distance from a compaction probe i f a cone resistance p r o f i l e i s a v a i l a b l e for the unimproved s o i l . The Phoenix process can r e s u l t i n reduced cone resistances to be measured following compaction treatment. Such reductions have been attributed to starvation of b a c k f i l l at the probe t i p . 108 To achieve best ef f e c t s , d e n s i f i c a t i o n probes must be patterned on configurations that confine areas of s o i l , such as t r i a n g l e s . For the s o i l conditions encountered at the research s i t e a maximum triangular probe spacing of 1.8m i s recommended. At such a spacing a minimum r e l a t i v e density of 70% i s estimated. The work performed has demonstrated the importance of the drainage aspect of the instrument. By pumping water from the s o i l during compaction treatment the cone resistance may be improved by up to double that attainable by vibrat i o n alone. The Phoenix Machine compares well with other equipment available i n the marketplace, and i f spacing requirements and probe si z e are taken into consideration, i s a highly e f f i c i e n t d e n s i f i c a t i o n system. 109 7. SUMMARY AND CONCLUSIONS The primary objectives of t h i s research were the evaluation of the performance of the Phoenix de n s i f i c a t i o n system and an investigation of the influence of operational parameters. This Chapter summarizes the p r i n c i p a l findings of the research and makes recommendations based on the experience with the Phoenix system. 7.1 Equipment and Procedures The f r i c t i o n r a t i o from a cone t e s t , and the material index from a f l a t dilatometer t e s t are powerful s o i l type indicators which are independent of changes i n r e l a t i v e density, s t i f f n e s s , and stress conditions. The seismic piezocone test i s i n s e n s i t i v e to changes i n s o i l s t i f f n e s s induced by the vibrocompaction process. More developmental work i s needed on the Phoenix apparatus. Improvements should be directed to improve the design of the a i r l i f t system to increase i t s r e l i a b i l i t y and e f f i c i e n c y as a water pumping mechanism. The design of the f i l t e r u n i t should be improved to reduce blocking by fine s o i l grains. The a i r motor design could benefit from an improved one way valve system to prevent s o i l ingress into the motor unit. Such s o i l ingress resulted i n considerable downtime whilst the motor was cleaned out. 110 7.2 Performance The Phoenix Machine i s an e f f i c i e n t means of densifying granular, saturated s o i l s i n s i t u . In terms of r e l a t i v e density, improvements up to 85-90% are consistently achieved, independently of the i n i t i a l s t a r t i n g density and overburden stress. The process improves the engineering c h a r a c t e r i s t i c s of ground primarily by increasing the r e l a t i v e density of the granular s o i l , and secondly by an increase i n e f f e c t i v e horizontal stress. The maximum r e l a t i v e densities achievable should be reduced by 5% to -take into consideration increases i n horizontal stress caused by the d e n s i f i c a t i o n process. The degree of compaction achievable diminishes with increasing distance around a singl e Phoenix probe, and i n an approximately exponential form. A r e l a t i o n s h i p has been developed to predict the v a r i a t i o n of cone resistance around a singl e Phoenix probe. The re l a t i o n s h i p i s v a l i d for f i l l sand and naturally deposited sand at two d i f f e r e n t i n i t i a l d e nsities, and at two d i f f e r e n t stress l e v e l s . The Phoenix technique i s suited to fi n e , s i l t y sand, but was unable to cause improvement to s i l t except by s o i l mixing. In addition, treatment should not be attempted beneath a layer of fi n e grained s o i l , as t h i s may lead to starvation of granular b a c k f i l l at the t i p and associated poor compaction. I l l The drainage aspect plays a s i g n i f i c a n t role within the o v e r a l l Phoenix d e n s i f i c a t i o n process. Pumping out water during the compaction treatment may increase the cone resistance by up to double that attainable by v i b r a t i o n treatment alone. This i s an important finding since i t i s t h i s aspect which sets the Phoenix process apart from other processes of vibrocompaction. The improvements to s o i l properties imparted by the Phoenix process accompany treatment or follow almost immediately a f t e r completion of treatment. The Phoenix Machine compares favourably with other equipment avail a b l e i n the marketplace, i f spacing requirements and probe s i z e are taken into consideration. In f a c t , the small s i z e of the equipment has enabled i t s deployment i n sp e c i a l situations where larger equipment could not be u t i l i z e d . 7 . 3 Recommendations The s o i l conditions at the area of the Annacis s i t e remaining f o r the UBC f i e l d t e sts were not as well suited to demonstrate the compaction equipment as those i n which the e a r l i e r t e s t s were performed. Ideally such f i e l d t e sts should be conducted at a s i t e with a uniform s o i l p r o f i l e c o n sisting only of loose, clean sand. To achieve best e f f e c t s , d e n s i f i c a t i o n probes must be patterned on configurations that confine areas of s o i l , such 112 as t r i a n g l e s . For the s o i l conditions encountered at the research s i t e a maximum triangular probe spacing of l.8m i s recommended. At such a spacing a minimum r e l a t i v e density of 70% i s estimated. The process can be responsible for reduced cone resistances to be measured following compaction treatment. Such reductions have been attributed to starvation of b a c k f i l l at the probe t i p . B a c k f i l l starvation may be overcome by maintaining an adequate supply of b a c k f i l l sand at the surface. To ensure submergence and a s s i s t the downward passage of b a c k f i l l , i t i s recommended to maintain a high water l e v e l within the bore by the addition of water at the surface. The deployment of the Phoenix equipment from a d r i l l r i g was i n e f f i c i e n t and li m i t e d the number of Phoenix probes available f o r the f i e l d t e s t s . A more e f f i c i e n t deployment system, based on a backhoe arm i s under consideration by Phoenix Limited. The l i m i t a t i o n s imposed by the f i e l d t e sts means that c e r t a i n aspects of the investigation could benefit from continued study. 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Rf «) (bar) Oc (bar) U <a. of voter) Ratio AU/Bc Depth Incromont • .05 n Max Depth i 12. 45 m U B C I INI S I T u T E : S _ r i N G S i t o L o c a t i o n . A N N A C I S N P I E R C P T D a t a i 1 2 / 0 6 / 8 7 F i l o i P E 4 . D A T O n S i t s L o c i 0 . 9 m FROM P R O B E C o n a U a e d i W. GEO S T D P P C o m m Q n t a i FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf 03 (bar) Qc (bar) U Cm. of water) Ratio 4U/0c D e p t h I n c r a m a n t • . 0 5 m M a x D e p t h i 1 1 . 7 5 m U B C I M S I T U T E S " r i M G S i t e Location. ANNACIS N PIER CPT Dato • 17/0B/B7 F i l e . PE5.DAT On S i t e Loci 1.5m FROM PROBE Cons Uaodi W. GEO STD PP Comments! FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf CD (bar) Oc (bar) U (*. of vater) Ratio AU/Oc X Depth Increment i . 05 m Max Depth • 10. 55 m UBC I M S I X U T E S " r i M G S i t e Locotiom ANNACIS N PIER CPT Date t 17/06/87 Fi 1 a i po6. dat On S i t e Loc. AT PROBE Cone Usedi W. GEO STD PP Comments! FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf tt) (bar) Oc (bar) U (n. of «ater> Ratio AU/Oc H Depth Increment i ,05 in Max Depth i 9.60 n U B C I M S I T U T EI S -r i M G S i t e Location! ANNACIS N PIER CPT Date i 17/06/87 F1 1 ei pa7. dat On S i t e Loci 0. 6m FROM PROBE Cone Ussdi W. GEO STD PP Commentoi FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P. P. Rf (X) (bar) Oc (bar) U (n. of water) Ratio AU/Oc Depth Increment i . 05 m Max Depth t 9.80 m M S I T U T EE S ~ r i M c S i t e L o c a t i o n ! A N N A C I S N P I E R C P T D a t e i 1 7 / 0 6 / 8 7 F i l e i p e B . d a t On S i t e L o c i 1 .5m FROM P R O B E C o n e U e o d i W. G E O S T D P P C o m m e n t e i FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. RF (X) (bar) Qc (bar) U (n. of water) Ratio AU/Qc D e p t h I n c r e m e n t i . 0 5 m Max D e p t h • 9 . 6 5 m UBC I Nl SIT U TES TIMS S i t e Location! ANNACIS N PIER CPT Date • 18/06/87 F i l e i pe9.dat On S i to Loci AT PROBE Cone Usodi W. GEO STO PP Comments! FRICTION RATIO Rf tt) 0 5 SLEEVE FRICTION (bar) CONE BEARING Oc (bar) 250 PORE PRESSURE U (m. of later) -10 0 40 0 5-10-Depth Increment i .05 m 154-Max Depth i 8. 90 m DIFFERENTIAL P.P. Ratio AU/Oc -.2 0 .8 0 10-U B C I KI S I T U T EE S " T I N G S i t e Location! ANNACIS N PIER CPT Date i 18/06/87 F i l e i pelO.dat On S i t e Loci 0.75m FROM PROBE Cone Usedi W. GEO STD PP Commentei FRICTION RATIO Rf a) 0 5 ai c 4-> Q) E Q_ LU a SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) 250 PORE PRESSURE U (m. of vater) rlO 0 40 5" 10-15 DIFFERENTIAL P.P. Ratio AUVQc .2 Q .8 10 15 Depth Increment i . 05 m Max Depth i 8. 90 m U B C I Kl S i t e Locatlom ANNACIS N PIER On S i t e Loci 1.5m FROM PROBE S I T U T EE CPT Date . 18/06/B7 Cone Used. W. GEO STD PP S T I M G F i l e , p e l l . d a t Comments! FRICTION RATIO Rf CD SLEEVE FRICTION (bar) 0 . Z CONE BEARING Oc (bar) PORE PRESSURE U (n. of la t e r ) :10 0 . 40 10 15-1 DIFFERENTIAL P.P. Ratio AU/Qc -.2 0 .8 5-10-15 A Depth Increment i . 05 m Max Depth t 8. 15 m I M S I T U "TEST I M G S i t e Location. ANNACIS N PIER On S i t e Loc. 1.5m FROM PROBE CPT Date . 22/0B/B7 Cone Used. W. GEO STD PP F i l e . PE12.DAT Commentei FRICTION RATIO Rf CD Q 5 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Oc (bar) 250 PORE PRESSURE U (a. of water) -10 0 T T 10-40 Depth Increment . .05 n 15-*-Max Depth . 9.81 a DIFFERENTIAL P.P. Ratio AU/Qc 10 15 .8 UBC I M S I T U TES" r i M s S i t e Location. ANNACIS N PIER CPT Date « 22/06/87 F i l e . PE14.DAT On S i t e Loc. 0.3m FROM PROBE Cone Used. W. GEO STD PP Comments. FRICTION RATIO Rf (Z) 0 5 SLEEVE FRICTION (bar) 0 ? CONE BEARING Oc (bar) PORE PRESSURE U (a. of water) -10 Q 40 10 IS DIFFERENTIAL P.P. Ratio AU/Oc -.2 0 .8 10 15 Depth Increment . . OS m Max Depth . 9. 59 m U B C I KI S I T U T E S " T I N S S i t e Location! ANNACIS N PIER CPT Oate i 24/08/87 F l l e i PE23.DAT On S i t e Loci 0. Bm FROM PROBE Cone Usedi W. GEO STD PP Commentei FRICTION RATIO Rf (X) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Oc (bar) Depth Increment • PORE PRESSURE U (m. of water) -10 0 40 OH 5-10 15 DIFFERENTIAL P.P. Ratio AU/Qc -.2 0 .8 0 10 15 Max Depth i 8. 80 m U B C I KJ S I T U T E S T I M G S i t o L o c a t i o n ! A N N A C I S N P I E R O n S i t o L o c i 1 . 5 m FROM P R O B E C P T D a t a . 2 4 / 0 6 / 8 7 C o n a U s e d . W. GEO S T D P P F i l e . P E 2 4 . D A T C o m m e n t e i FRICTION RATIO Rf (X) 0 5 lfr 15-SLEEVE FRICTION (bar) 0 ? D e p t h I n c r e m e n t CONE BEARING Oc (bar) 250 PORE PRESSURE U (m. of water) -10 0 40 5 10 15 0 5 Max D e p t h i 1 9 . 3 2 m DIFFERENTIAL P.P. Ratio AU/Oc -.2 0 . . .8 10 15 U B C I N S i t e L o c a t i o n . A N N A C I S N P I E R O n S i t e L o c . 1 .5m FROM P R O B E S I T U T E S C P T D a t o . 2 4 / 0 6 / 8 7 C o n e U s e d . W. GEO S T D P P T I NG F i l e . P E 2 4 . D A T C o m m e n t s . FRICTION RATIO SLEEVE FRICTION Rf CO (bar) CONE BEARING Oc (bar) PORE PRESSURE DIFFERENTIAL P. P. U (a. of water) Ratio AU/Qc 15 2a w 0) L -P 0) E 0_ LU a 25 30*- _ i i t _ 15 20-250 -10 15 20-25 30 40 15 2 0 20-25 30 D e p t h I n c r e m e n t . . 0 5 m M a x D e p t h > 1 9 . 3 2 m UBC I N S I T U TES " r i N s S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t e . 1 0 / 0 7 / 8 7 F i l e . P E A . D A T O n S i t o L o c i 0 . 3 8 m FROM P R O B E C o n e U s e d . W. GEO S T O P P C o m m e n t s . FRICTION RATIO Rf tt) Q 5 SLEEVE FRICTION (bar) 0 . . 2 CONE BEARING Qc (bar) 250 PORE PRESSURE U (a. of water) -10 0 40 10-15 DIFFERENTIAL P.P. Ratio AU/Oc -.2 0 -8 0 10-15 D e p t h I n c r e m e n t . . 0 5 in Max D e p t h . 9 . 7 9 in U B C I N S I T UJ T EE S ~ r i N s S i t e Location. ANNACIS N PIER CPT DatQ . 10/07/87 F i l e . PEB.DAT On S i t e Loc. 0.75m FROM PROBE Cone Used. W. GEO STD PP Comments. FRICTION RATIO Rf (X) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U On. of water) -10 0 40 5-10 15 DIFFERENTIAL P.P. Ratio AU/Qc -.2 0 .8 0 10 15 Depth Increment . .05 m Max Depth . 8.71 m UBC I M S i t o L o c a t i o n . A N N A C I S N P I E R O n S i t e L o c . 1 . 5 m FROM P R O B E S I T U C P T D a t a . 1 0 / 0 7 / 8 7 C o n a U s e d . W. G E O S T D P P T E S T I MS F i l e . P E C . D A T C o m m e n t e i FRICTION RATIO Rf CD 0 5 SLEEVE FRICTION (bar) 0 2 0+ 10-CONE BEARING Qc (bar) PORE PRESSURE U (m. of water) -10 0 40 10 15 DIFFERENTIAL P.P. Ratio AU/Oc -.2 0 .8 10-15 D e p t h I n c r e m e n t > . 0 5 m Max D e p t h . 8 . 7 4 m UBC I INI SIT" U T E S "TIMS S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t e i 1 0 / 0 7 / 8 7 F i l e . P E D . D A T O n S i t e L o c i 0 . 7 5 m FROM P R O B E C o n e U g o d i W. G E O S T D P P C o m m e n t s i FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf (I) (bar) Oc (bar) U (m. of water) Ratio AU/Qc D e p t h I n c r e m e n t i . 0 5 m M a x D e p t h i 9 . 6 1 m U B C I Kl S I T UJ T B S " T I N G S i t e Location. ANNACIS N PIER CPT Dato . 7/09/87 F i l e . PHI. DAT On S i to Loc. AT PROBE Cone Used. W. GEO STD PP Comments. FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf CD (bar) Oc (bar) U (a. of water) Ratio AU/Qc Depth Increment . . 05 m Max Depth . 6.30 n U B CZ I INI S I T U TES" r i INI s S i t e L o c a t1 o n i ANNACIS N PIER CPT Da t a i 7/09/B7 F i l e i p h2.dat On S i t e L o c i 0.9m FROM PROBE Cons Ueadi W. GEO STD PP Commsntsi FRICTION RATIO Rf (X) 0 5 SLEEVE FRICTION (bar) g 2 CONE BEARING Qc (bar) 250 PORE PRESSURE U (m. of water) -10 0 . . 40 5-10-15 DIFFERENTIAL P. P, Ratio AU/Qc -.2 0 .8 0 ' H Depth Increment • .05 m Max Depth i 1 1 . 55 m U B C I N S I T U T E S " F I N C S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t a . 7 / 0 9 / 8 7 F i l e . P H 3 . D A T O n S i t o L o c . 0 . 4 5 m FROM P R O B E C o n e U s e d . W. GEO S T D P P C o m m e n t s . FRICTION RATIO Rf CO 0 5 SLEEVE FRICTION (bar) Q . . 2 CONE BEARING flc (bar) 250 PORE PRESSURE U (a. of voter) -10 Q . 4 0 10-15 DIFFERENTIAL P.P. Ratio AU/flc -.2 0 .8 10-15 D e p t h I n c r e m e n t . . 0 5 m M a x D e p t h • 8 . 7 5 M S I X U TBS" r i M s S i t s L o c a t i o n . ANNACIS N PIER CPT Date • 7/09/87 F i l e . PH5.DAT On S i t e Loc. 1.5m FROM PROBE Cone Used. W. GEO STD PP Comments. FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf a) (bar) Qc (bar) U (n. of water) Ratio AU/Qc Depth Increment • . 05 m Max Depth • 9.80 m U B C I M S i t e L o c a t i o n . A N N A C I S N P I E R O n S i t e L o c . 0 . 7 5 m FROM P R O B E 3 I T U C P T O a t o . 7 / 0 9 / 8 7 C o n e U s e d . V. G E O S T O P P S T I N G F i l e . P H 6 . D A T C o m m e n t s . FRICTION RATIO Rf CD Q . . 5 SLEEVE FRICTION (bar) 0 . . . ? CONE BEARING Qc (bar) PORE PRESSURE U OL of voter) -10 Q . 40 DIFFERENTIAL P.P. Ratio AU/Oc 10 15-10 15 D e p t h I n c r e m e n t . . 0 5 m Max D e p t h . B . 5 5 n M S I T U T B S " r i M s S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t a • 7 / 0 9 / 8 7 F i l e . P H 7 . D A T O n S i t e L o c . A T P R O B E C o n e U s e d . W. G E O S T D P P C o m m e n t s . FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf CD (bar) Oc (bar) U Ou of water) Ratio AU/Qc D o p t h I n c r e m e n t . . 0 5 m Max D e p t h • 6 . 8 5 m U B C I M S I T " UJ T B S " r i M s S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t e • 7 / 0 9 / 8 7 F i l e . P H 8 . D A T O n S i t o L o c . 0 . 3 m FROM P R O B E C o n e U s e d . W. G E O S T D P P C o m m e n t s . FRICTION RATIO Rf CD Q 5 0-' SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U (m. of water) -10 0 40 10 15 DIFFERENTIAL P.P, Ratio AU/Oc -•? 0 -8 0 ' ' 5 10 IS D e p t h I n c r e m e n t • . 0 5 m M a x D e p t h . 8 . 7 5 » U B C I M S I T U T E S " F I N S S i t e L o c a t i o n ! A N N A C I S N P I E R C P T D a t e i 7 / 0 9 / 8 7 F l l e i P H 9 . D A T O n S i t e L o c i 0 . 6 m FROM P R O B E C o n e U s e d i W. GEO S T D P P C o m m e n t s ! FRICTION RATIO Rf CD g 5 10 15-SLEEVE FRICTION (bar) 0 . . 2 CONE BEARING Qc (bar) 250 PORE PRESSURE U (a. of water) 1° Q . . . *P 5 10-D e p t h I n c r e m e n t • . 0 5 n 15 M a x D e p t h i 8 . 7 0 m DIFFERENTIAL P.P. Ratio AU/Qc - . 2 0 .8 0 5-10 15 U B C I M S I T U T" EE ' B * T I N G S i t e L o c a t i o n s A N N A C I S N P I E R C P T D a t a i 7 / 0 9 / 8 7 F l l a i P H 1 0 . D A T O n S i t e L o c i 0 . 9 m FROM P R O B E C o n e U s e d i W. G E O S T D P P C o m m o n t e i FRICTION RATIO Rf CO 0 5 SLEEVE FRICTION (bar) Q . . . . 2 CONE BEARING Qc (bar) 250 PORE PRESSURE U (a. of water) 10 Q . 40 10-15 DIFFERENTIAL P.P, Ratio AU/Qc - . 2 0 .8 0-D e p t h I n c r e m e n t • . 0 5 in M a x D e p t h i 8 . 8 5 m U B C I M S I T U ~TES~ r i M c S i t o L o c a t i o n . A N N A C I S N P I E R C P T D a t e . 7 / 0 9 / B 7 F i l e . P H I 1. D A T O n S i t o L o c . 1 .2m FROM P R O B E C o n o U s e d . W. GEO S T D P P C o m m e n t s . FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf a) (bar) Oc (bar) U Cm. of water) Ratio AU/Oc X D e p t h I n c r e m e n t . . 0 5 n M a x D e p t h . 8 . 7 0 in UBC I NJ SIT" U T " EZ S T I MS S i t e L o c a t i o n ! A N N A C I S N P I E R C P T D a t e i 1 8 / 0 8 / 8 8 F i l e i A N P 1 . E D T O n S i t e L o c i P R E - T R I A L C o n e U s e d i UBC#7 S T D P P C o m m e n t s i 2 0 m SW OF ANP SERIES FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. R f (Z) (bar ) Qc (bar ) U (m. o f wa te r ) R a t i o AU/Qc D e p t h I n c r e m e n t : . 0 2 5 m Max D e p t h i 9 . 9 3 m U E3 C I M S I T U T E S " r i M G S i t e L o c a t i o n i A N N A C I S N P I E R C P T D a t e . 0 1 / 0 9 / 8 8 F i l e i A N P 5 . E D T O n S i t e L o c . P R E - T R I A L C o n e U s e d i HOG S T D P P C o m m e n t s ! FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. R f tt) (bar ) Qc (bar) U (m. o f water ) R a t i o AU/Oc D e p t h I n c r e m e n t i . 0 2 5 m Max D e p t h i 1 4 . 7 3 m 1 1 E3 C I Kl SIT " U ~T EE s ~ r i M s S i t e L o c a t i o n ! A N N A C I S N P I E R C P T O a t e i 0 9 / 0 9 / 8 8 F i l e . A N P 6 . E D T O n S i t e L o c i P R E - T R I A L C o n e U s e d i HOG S T D P P C o m m e n t s . FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P. P. Rf (Z) (bar) Qc (bar) U (m. of water) Ratio AU/Qc X D e p t h I n c r e m e n t i . 0 2 5 m M a x D e p t h i 2 0 . 5 8 m U E3 C I M S i t e L o c a t i o n . ANNACIS N P I E R On S i t e L o c . P R E - T R I A L S I T U T EE 5 CPT D a t e . 0 9 / 0 9 / 8 8 C o n e U s e d . HOG STD PP 3 T I M G F i l e . ANP6.EDT . Comments. FRICTION RATIO SLEEVE FRICTION Rf (JO (bar) CONE BEARING Qc (bar) PORE PRESSURE DIFFERENTIAL P. P. U (m. of water) Ratio AU/Qc 25-20-25 30* -10 151 20 25 30 40 D e p t h I n c r e m e n t . . 0 2 5 m Max D e p t h i 2 0 . 5 8 m - . 2 Q 15 20 25 30 U B C I M SIT " U "TBS" r i M s S i t e L o c a t i o n i A N N A C I S N P I E R C P T D a t e • 2 4 / 0 9 / B 8 F i l e . A N P 7 . E D T O n S i t e L o c i P R E - T R I A L C o n e U s e d i HOG S T D P P C o m m e n t s . FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf a) (bar) Qc (bar) U (m. of «oter) Ratio AU/Qc D e p t h I n c r e m e n t i . 0 2 5 m Max D e p t h • 1 2 . 4 8 m U B C I M S I T u T E: S • F I N S S i t e L o c a t i o n i A N N A C I S N P I E R C P T D o t e i 2 6 / 0 9 / 8 8 F i l e i A N P 9 . E D T O n S i t e L o c i P R E - T R I A L C o n e U s e d i UBC 07 S T D P P C o m m e n t s i S E I S M I C C P T FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf (X) (bar) Qc (bar) U (m. of water) Ratio AU/Qc D e p t h I n c r e m e n t i . 0 2 5 m M a x D e p t h • 1 4 . 7 7 m UBC IN SIT U TES" TING S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t e • 7/10/88 F i l e . A N P 1 0 . E D T O n S i t e L o c i A T P R O B E #5 C o n e U s e d i HOG S T D P P C o m m e n t s i A F T E R 1 D A Y FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf tt) (bar) Qc (bar) U (m. of water) Rotio AU/Qc X D e p t h I n c r e m e n t t .025 m Max D e p t h • 1 4 . 4 3 m U B C I M S I T U : T B S T I N G S i t e L o c a t i o n i A N N A C I S N P I E R C P T D a t e i 7 / 1 0 / 8 8 F i l e i A N P 1 1 . E D T . O n S i t e L o c i A T P R O B E * 1 0 C o n e U s e d i H O G S T D P P C o m m e n t s ! A F T E R 3 H R S FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf tt) (bar ) Qc (bar ) U (m. o f wa te r ) R a t i o AU/Qc D e p t h I n c r e m e n t : . 0 2 5 m M a x D e p t h i 1 5 . 0 1 m UBC I [XI I TU T EE S i t e L o c a t i o n i On S i t e L o c i ANNACIS N PIER AT PROBE #16 CPT Date i Cone Usedt 8 / 1 0 / 8 8 UBC08 STD PP T I N G F i l e i ANP12 .EOT Commentst AFTER 1 HOUR FRICTION RATIO Rf (Z) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) 250 PORE PRESSURE U (m. of water) -10 0 40 10 15 DIFFERENTIAL P.P. Ratio AU/Qc -.2 0 o-Depth Increment i . 0 2 5 m Max D e p t h i 15 .81 m M S I T U T B S B . T I M G S i t e L o c a t i o n i ANNACIS N PIER CPT Date i 1 4 / 1 0 / 8 8 F i l e . ANP14 .EDT On S i t e L o c i MIO-PROBE 2. 5m Cone Usedi HOG STD PP Comments! WITHOUT DRAIN FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf (*) (bar) Qc (bar) U (m. of water) Ratio AU/Qc X D e p t h Increment i . 0 2 5 m Max D e p t h : 13. 78 m I M S i t e L o c a t i o n . ANNACIS N PIER On S i t e L o c . AT PROBE #7 S I T U CPT Date . 1 8 / 1 0 / 8 8 Cone Used . HOG STD PP S T I N G F i l e . ANP15 .EDT Comments. AFTER 12 DAYS (/) 01 L -P QI E 0_ UJ a FRICTION RATIO Rf (Z) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) 250 PORE PRESSURE U (m. of water) -10 Q 40 10 15 DIFFERENTIAL P.P. Ratio AU/Qc -.2 0 .8 10 15 H cn 0\ Depth Increment . . 0 2 5 Max D e p t h . 14. 61 m U B C I M S IT " U TEE B T I N G . S i t e L o c a t i o n i ANNACIS N PIER CPT D a t e i ••• 1 8 / 1 0 / 8 8 F i l e i A N P 1 5 . E O T On S i t e L o c i MID-PROBE 2. 5m Cone Usedi HOG STD PP Comments! AFTER 11 DAYS FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf (X) (bar) Oc (bar) U (m. of water) Ratio AU/Qc D e p t h Increment i . 0 2 5 m Max D e p t h i 14. 53 m 1 1 B C IN S i t e L o c a t i o n . ANNACIS N P I E R On S i t e L o c . 0.6m FROM PROBE S I T U T E CPT D a t e . 1 9 / 1 0 / 8 8 C o n e U s e d . HOG STD P P 1 S T I N G F i l e . ANP17. EDT Comments. AFTER 12 DAYS FRICTION RATIO SLEEVE FRICTION Rf (Z) (bar) CONE BEARING Qc (bar) PORE PRESSURE DIFFERENTIAL P.P. U (n. of water) Ratio AU/Qc io- 10 250 1 1 1 1 I I t l l _ -10 0 0-10 154-40 D e p t h I n c r e m e n t . . 0 2 5 m Max D e p t h . 14. 6 8 m -.2 0 0 10-15 .8 U B C I N S i t e L o c a t i o n i ANNACIS N PIER On S i t e L o c i 0.25m FROM PROBE S I T U T E CPT Date i 1 9 / 1 0 / 8 8 Cone Usedi HOG STO PP T I N G F i l e i ANP 1 8. EDT Commentsi AFTER 12 DAYS CO CD L +J CD E 0~ UJ a FRICTION RATIO Rf (X) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Oc (bar) 250 PORE PRESSURE U (m. of water) -10 0 40 5-DIFFERENTIAL P.-P, Ratio AU/Qc -.2 0 .8 0 H D e p t h Increment i . 0 2 5 m Max D e p t h • 13. 95 m U B cr i M S I T U T E S " T ING S i t e L o c a t i o n ! ANNACIS N PIER CPT D a t e i 1 9 / 1 0 / 8 8 F i l e . ANP19 .EDT On S i t e L o c i 0.4m FROM PROBE Cone Usedi HOG STD PP Comments. WITHOUT DRAIN (/) 0j L -P QI E 0_ UJ a FRICTION RATIO Rf CO 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U (m. of water) -10 0 40 lo-ts4 DIFFERENTIAL P.P. Ratio AU/Qc -.2 0 .8 0 -10 15-1 H O D e p t h Increment t . 025 m Max D e p t h . 14. 48 m UBS I M S i t e L o c a t i o n i ANNACIS N PIER On S i t e L o c i 0.85m FROM PROBE D I Tl I T B S CPT Date i 1 9 / 1 0 / 8 8 Cone Usedi HOG STD PP T I'.M G F i l e i ANP20. EDT Comments. WITHOUT DRAIN FRICTION RATIO Rf <Z) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U (n. of water) -10 0 40 10 15 DIFFERENTIAL P.P. Ratio AU/Qc -.2 0 10-15 D e p t h Increment , 025 m Max D e p t h i 14 .63 m U B C I KI S i t e L o c a t i o n . ANNACIS N PIER On S i t e L o c i 0.55m FROM PROBE I T U CPT Date i 2 9 / 1 0 / 8 8 Cone Usedi HOG STD PP T E S T I N G F i l e . A N P 2 1 . E D T Comments. WITHOUT DRAIN FRICTION RATIO Rf tt) 0 5 '.0 15 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U (in. of water) -10 0 40 DIFFERENTIAL P.P. Ratio AU/Qc .2 0 .8 D e p t h Increment . . 025 m Max D e p t h . 14 .59 m UBC I INI S I T U. T B S T I M S S i t e L o c a t i o n i ANNACIS N PIER CPT Date i 2 9 / 1 0 / 8 8 F i l e . ANP22. EDT On S i t e L o c i 0. 2m FROM PROBE Cone Usedi HOG STD PP Comments! WITHOUT DRAIN (/) CD L 4-> Q) E 0_ LU Q FRICTION RATIO Rf (X) SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U (m. of water) -10 0 40 DIFFERENTIAL P.P. Ratio AU/Oc -.2 0 . B H CTi D e p t h Increment . . 025 m Max D e p t h i 1 4 . 6 3 U B C I N S i t e L o c a t i o n ! A N N A C I S N P I E R O n S i t e L o c i 0 . 4 5 m FROM P R O B E 3 I Tl I T EZ C P T D a t e . 2 9 / 1 0 / 8 8 C o n e U s e d i HOG S T D P P T I N G F i l e . A N P 2 3 . E D T C o m m e n t s . W I T H O U T D R A I N (/) QI L. •P ai E 0_ UJ a FRICTION RATIO Rf (X) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U (in. of water) -10 0 40 10-15 _ j 1 t _ DIFFERENTIAL P.P. Ratio AU/Qc -.2 0 .8 0 D e p t h I n c r e m e n t . . 0 2 5 m Max D e p t h « 1 4 . 10 m U B C IM S I T U T E S T I N G S i t e L o c a t i o n i ANNACIS N PIER On S i t e L o c i 0.85m FROM PROBE CPT Date i 2 9 / 1 0 / 8 B Cone Usedi HOG STD PP F i l e i ANP24. EDT Commentsi WITHOUT DRAIN CO ai L -P ai E 0_ LU Q FRICTION RATIO Rf (X) 0 5 10-1 5 j — , — , — , — SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) 250 PORE PRESSURE U (m. of water) -10 0 40 0 10 15 —1 I l _ DIFFERENTIAL P.P, Ratio AU/Qc -.2 0 .8 0 H (Jl D e p t h Increment , i . 0 2 5 m Max D e p t h i 14. 63 m U B C . I N S I T UJ T E S " r i N s SitQ Location. ANNACIS N PIER CPT Date i 29/10/88 F i l e . ANP25.EDT On S i t e Loci 0.55m FROM PROBE Cone Usedi HOG STD PP Comments. AFTER 3 WEEKS FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P. P. R f CO (bar ) Qc (bar ) U <•. o f wa te r ) R a t i o AU/Oc Depth Increment > .025 m Max Depth . 14.53 m l_J E3 C I M S IT " ^ j | j'1 "" ^ ~ — T I M S S i t a L o c a t i o n i ANNACIS N PIER CPT Date • 29/10/88 F i l e i ANP26.EDT On S i t e L o c i 1.0m FROM PROBE Cone Usedi HOG STD PP Commentsi AFTER 3 WEEKS FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf (X) (bar) Qc (bar) U (m. of water) Ratio AU/Oc Depth Increment • .025 m Max Depth • 14. 63 m UBC IN S l t o L o c a t i o n . A N N A C I S N P I E R O n S i t e L o c . 0 . 3 5 m FROM P R O B E S I T U TBS C P T D a t e . 2 9 / 1 0 / 8 8 C o n e U s e d . HOG S T D P P T I NC F i l e . A N P 2 7 . E D T C o m m e n t s . A F T E R 3 W E E K S FRICTION RATIO SLEEVE FRICTION Rf (X) (bar) CONE BEARING Qc (bar) PORE PRESSURE DIFFERENTIAL P.P. U Cm. of water) Ratio AU/Qc (0 QI L -P a E 0_ ill a -10 p 10 15 40 . 2 P 10-15 cn CO D e p t h I n c r e m e n t • . 0 2 5 m M a x D e p t h . 1 3 . 3 5 m U B S I M S I T U T B S T I M S S i t e L o c a t i o n i A N N A C I S N P I E R C P T D a t a • 2 9 / 1 0 / 8 8 F i l e . A N P 2 8 . E D T O n S i t e L o c i 0 . 2 m FROM P R O B E C o n e U s e d i HOG S T D P P C o m m e n t e i A F T E R 3 W E E K S FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf (X) (bar) Qc (bar) U (m. of water) Ratio AU/Oc D e p t h I n c r e m e n t i . 0 2 5 m M a x D e p t h . 1 3 . 3 8 m U B C I M S i t e L o c a t i o n i A N N A C I S N P I E R O n S i t e L o c i 0 . 8 5 m FROM P R O B E S I T U T B S C P T D a t a . 2 9 / 1 0 / 8 8 C o n e U s e d . HOG S T D P P T I M S F i l e . A N P 2 9 . E D T C o m m e n t s . A T 3 W E E K S FRICTION RATIO SLEEVE FRICTION Rf (X) (bar) CONE BEARING Qc (bar) PORE PRESSURE DIFFERENTIAL P.P. U (ra. of water) Ratio AU/Oc 10 0 5 10-15 40 .2 0 10 15-1-UBC I INI S I T U TES" r i INI s S i t a L o c a t i o n . A N N A C I S N P I E R C P T D a t a . 4 / 1 1 / 8 8 F i l o . A N P 3 0 . E D T O n S i t e L o c . 0 . 3 m FROM P R O B E C o n e U s e d . HOG S T D P P C o m m e n t s . 6 M I N N M E T R E FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf GO (bar) Qc (bar) U On. of water) Ratio AU/Oc X D e p t h I n c r e m e n t . . 0 2 5 m M a x D e p t h > 1 3 . 3 8 m UBC I M S I T U T EZ S T I M CC S i t e L o c a t i o n i A N N A C I S N P I E R C P T D a t e i 4 / 1 1 / 8 8 F i l e i a n p 3 1 . e d t O n S i t e L o c i 0 . 6 m FROM P R O B E C o n e U s e d . HOG S T D P P C o m m e n t s i 6 M I N / M E T R E FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf (X) (bar) Oc (bar) U (n. of later) Ratio AU/Uc D e p t h I n c r e m e n t . . 0 2 5 m Max D e p t h . 1 4 . 2 0 m U B C I M S I T U T E S " T I N G S i t a L o c a t i o n i A N N A C I S N P I E R C P T D a t a i 4 / 1 1 / 8 8 F i l e i a n p 3 2 . e d t On S i t a L o c i 0 . 3 m FROM P R O B E C o n a U s e d i HOG S T D P P C o m m a n t o i 4 M I N / M E T R E FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf CO (bar) Qc (bar) U (m. of water) Ratio AU/Qc D e p t h I n c r e m e n t i . 0 2 5 m Max D e p t h • 1 3 . 7 8 m U B C I M S I T U T B S " r i M s S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t e . 4 / U / 8 8 F l l e . A N P 3 3 . E D T O n S i t o Loc« 0 . 6 m FROM P R O B E C o n e U s e d . HOG S T D P P C o m m e n t s . 4 M I N \ M E T R E FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf (X) (bar) Qc (bar) U (m. of water) Ratio AU/Qc D e p t h I n c r e m e n t i . 0 2 5 m M a x D e p t h . 1 3 . 6 5 m U B C I INI S I T L J T E S T I M S S i t e L o c a t i o n i A N N A C I S N P I E R C P T D a t a • 4 / 1 1 / 8 8 F i l e . A N P 3 4 . E D T On S i t e L o c i 0 . 3 m FROM P R O B E C o n e U s e d i HOG S T D P P C o m m e n t e i 2 M I N / M E T R E FRICTION RATIO R f CO 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Oc (bar ) 15-D e p t h I n c r e m e n t i . 0 2 5 m PORE PRESSURE U (•. o f wa te r ) -10 0 40 10 15 —I I L _ DIFFERENTIAL P.P, R a t i o AU/Oc .? Q . 8 M a x D e p t h i 1 2 . 4 8 m UBC I NJ S I T U T "ES" r i N s S i t e L o c a t i o n i ANNACIS N PIER CPT D a t e i 8 / 0 3 / 8 9 F i l e t A N P 3 5 . E D T On S i t e L o c . CENTROID 1 . 5m Cone Usedi UBC#7 STD pp Comments! S E I S M I C CPT (/) Q i L -P a i E CL LU a FRICTION RATIO Rf (X) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U On. of water) -10 0 40 10-15 DIFFERENTIAL P.P. Ratio AU/Qc -.21 p .8 0 10 15 H CM D e p t h I n c r e m e n t i . 0 2 5 m Max D e p t h i 1 0 . 7 3 m U B C I N S I T U T E S T I N G S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t e . 2 1 / 1 / 8 9 F i l e . A N P 3 6 . E D T O n S i t e L o c . C E N T R O I D 2 . 5 m C o n e U s e d . HOG S T D P P C o m m e n t s . W I T H O U T D R A I N FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf a) (bar) Qc (bar) U (m. of water) Ratio AU/Oc D e p t h I n c r e m e n t . . 0 2 5 m M a x D e p t h . 1 3 . 6 8 m U B C I M S i t e L o c a t i o n . A N N A C I S N P I E R O n S i t e L o c i C E N T R O I D 2 . 5 m 3 I T U C P T D a t e . 2 1 / 1 / 8 9 C o n e U s e d . HOG S T D P P S T I M G F i l e . A N P 3 7 . E D T C o m m e n t s . FRICTION RATIO Rf (X) 0 5 SLEEVE FRICTION (bar) 0 2 CONE BEARING Qc (bar) PORE PRESSURE U (m. of water) -10 0 40 5 10 15 DIFFERENTIAL P.P. Ratio AU/Qc 0 .8 - p 0* 10-15 D e p t h I n c r e m e n t . . 0 2 5 m M a x D e p t h . 1 3 . 7 6 m 1 I B C I M S I T U T E S " r i M s S i t e L o c a t i o n . A N N A C I S N P I E R C P T D a t e . 2 1 / 1 / 8 9 F i l e . a n p 3 8 . e d t O n S i t e L o c . C L O S E TO 0 5 C o n e U s e d . HOG S T D P P C o m m e n t e . FRICTION RATIO SLEEVE FRICTION CONE BEARING PORE PRESSURE DIFFERENTIAL P.P. Rf a) (bar) Oc (bar) U (m. of water) Ratio AU/Qc D e p t h I n c r e m e n t . . 0 2 5 m Max D e p t h . 1 3 . 8 1 m 

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