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The analysis and interpretation of the cone pressuremeter in cohesive soils Hers, Ian 1989-08-28

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THE ANALYSIS AND INTERPRETATION OF THE CONE PRESSTJREMETER IN COHESIVE SOILS by IAN HERS B.A.Sc, The University of British Columbia, 1986 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES Department of Civil Engineering We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA ^September, 1989 ©IAN HERS, 1989 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver, Canada Date DE-6 (2/88) ABSTRACT The cone pressuremeter is a promising new in situ testing device which combines the well known capabilities of a piezocone with a full displacement pressuremeter (FDPM). The focus of this thesis is to present results from FDPM tests performed as part of a cone pressuremeter sounding at three cohesive soil sites in the Vancouver area. The insertion of a cone pressuremeter results in a substantial amount of disturbance and the generation of excess pore pressures. As a result of the changing stress conditions, the length of the relaxation time or time delay between insertion and testing has a significant effect on the lift-off pressure and shape of the FDPM curve. Results indicate that increased relaxation periods lead to lower lift-off pressures. The strain rate used during a test is also significant with lower rates resulting in higher limit pressures and undrained shear strengths. Comparisons were made between the FDPM, self-boring pressuremeter (SBPM) and dilatometer lift-off and expansion pressures. FDPM test results are also influenced by the design and performance of the pressuremeter. Important equipment related considerations discussed are compliance,strain arm design and pressuremeter L/D ratio. The results of FDPM tests were used to estimate the undrained shear strength, shear modulus, stress history and in situ horizontal stress of cohesive soils and when possible compared to SBPM, field vane and dilatometer results. The use of cavity expansion theory for the analysis of the FDPM test is made difficult by the unknown stress conditions created by iii disturbance. Nevertheless, reasonable estimates of the undrained shear strength were made using cavity expansion methods with the FDPM undrained shear strength generally greater than the field vane and similar to those obtained from the SBPM test. Cavity contraction theory was also used to estimate the undrained shear strength with the results generally being less than the field vane undrained shear strength. Good comparisons were obtained between the FDPM and SBPM unload-reload shear moduli. Both the unload-reload shear moduli and the rigidity index were shown to attenuate with increasing shear strain. Two new methods using the rigidity index and normalized pressuremeter limit pressure were proposed to estimate stress history. Both techniques appear to be promising. Attempts to use the FDPM to estimate the in situ horizontal stress were unsuccessful when compared to the results of other available tests. iv TABLE OF CONTENTS Page ABSTRACT ii LIST OF TABLES vLIST OF FIGURES viACKNOWLEDGEMENTS x1.0 INTRODUCTION 1 2.0 EQUIPMENT AND TEST PROCEDURES 5 2.1 The UBC Seismic Cone Pressuremeter (SCP) 5 2.1.1 Description of the UBC SCP 5 2.1.2 The UBC SCP Data Acquisition System 11 2.1.3 Test Procedures for the UBC SCP 14 2.1.4 UBC SCP Compliance 18 2.2 The Fugro Cone Pressuremeter 21 2.3 The Hughes Self-Boring Pressuremeter (SBPM) 26 3.0 TEST SITES AND FIELD PROGRAMME 33 3.1 Scope 33.2 Site Descriptions and Field Programme 33 3.2.1 McDonald Farm3.2.2 Lulu Island UBC Pile Research 38 3.2.3 Langley Lower 232 .41 4.0 THE INTERPRETATION OF THE PRESSUREMETER TEST 45 4.1 Analytical Approaches to the Pressuremeter Test 45 4.2 Factors Affecting Pressuremeter Test Interpretation ....50 4.2.1 Effects of Pressuremeter Insertion and Relaxa tion Period 53 4.2.2 Effects of Strain Rate 57 4.2.3 Effects of Disturbance 9 4.2.4 Effects of Pressuremeter L/D Ratio 61 4.3 Comparison of SBPM and FDPM Tests 63 4.4 Parameters Obtained from the Pressuremeter Test ...72 4..4.1 Undrained Shear Strength 74.4.2 Shear Modulus 81 4.4.3 Stress History and In Situ Horizontal Stress ...86 5.0 UNDRAINED SHEAR STRENGTH 93 5.1 Reference Undrained Shear Strength 95.2 Theoretical Techniques 8 5.2.1 Windle and Wroth Average Strength Method 98 5.2.2 Arnold Curve Fitting Method 101 5.2.3 Houlsby Unloading Method 105.3 Empirical Techniques 104 5.4 Conclusions 113 V TABLE OF CONTENTS ( CONT. ) Page 6.0 SHEAR MODULUS AND RIGIDITY INDEX 115 6.1 Shear Modulus 116.2 Rigidity Index 121 6.3 Conclusions7.0 STRESS HISTORY AND IN SITU HORIZONTAL STRESS 129 7.1 Reference Overconsolidation Ratio 127.2 Stress History 127.3 Reference In Situ Horizontal Stress ; 131 7.4 In Situ Horizontal Stress 133 7.5 Conclusions 136 8.0 CONCLUSIONS AND RECOMMENDATIONS 139 8.1 Factors Affecting the Interpretation of the FDPM Test .139 8.2 Parameters Obtained from FDPM Tests 141 8.2.1 Undrained Shear Strength 148.2.2 Shear Modulus and Rigidity Index 143 8.2.3 Stress History and In Situ Horizontal Stress ..143 8.3 Recommendations 144 REFERENCES 146 APPENDICES I Pressuremeter Test Data at McDonald Farm 152 II Pressuremeter Test Data at Lulu Is-UBCPRS 247 III Pressuremeter Test Data at Langley Lower 232 363 IV Derivation of Unload Reload Shear Modulus 419 V Shear Modulus Values 425 VI In Situ Test Locations 430 vi LIST OF TABLES Table Page 1.1 Classification of Pressuremeters According to Method of Insertion (adapted from Huang and Haefele, 1988) 2 2.1 Test Depth and Drilling Parameters for the Hughes SBPM at McDonald Farm ( adapted from Hughes, 1984 ) 30 3.1 Soil Properties at McDonald Farm 37 3.2 In Situ Tests Performed at McDonald Farm 38 3.3 Soil Properties at Lulu Is. - UBCPRS 41 3.4 In Situ Tests Performed at Lulu Is. - UBCPRS 41 3.5 Soil Properties at Langley Lower 232 44 3.6 In Situ Tests Performed at Langley Lower 232 44 4.1 Effect of Relaxation Time on FDPM Lift Off Pressures at Lulu Is. - UBCPRS 55 4.2 Numerical Simulation of SBPM Tests with Varying L/D Ratios for Elastic Perfectly Plastic Soil •( after Baguelin et al, 1986) .62 4.3 Effect of Insertion Method on the Radius of the Plastic Zone for an Elastic Perfectly Plastic Soil 63 4.4 Comparison of Undrained Shear Strength from Pressuremeter, Field Vane and Triaxial Tests 80 vii LIST OF FIGURES Figure Page 2.1 Schematic of the UBC SCP 6 2.2 UBC SCP Strain Arm Design 8 2.3 Effect of Different Strain Arm Designs on the Lift-off Stage of a Pressure-Displacement Curve 10 2.4 Schematic Layout of the UBC SCP Data Acquisition System ....13 2.5 Typical Strain Arm Calibration for the UBC SCP 15 2.6 Membrane Correction Curve for the UBC SCP 17 2.7 Typical Strain Rate Used for a UBC SCP Test 19 2.8a,b Results of a UBC SCP Test Inside a 44 mm Diameter Steel Cylinder 20 2:9 Schematic of the Fugro CP ( after Withers et al, 1986 ) ....22 2.10 The Pressuremeter Component of the Fugro CP ( after Withers et al, 1986 ) 23 2.11 Strain Arm Calibration for the Fugro CP 25 2.12 Membrane Correction Curve for the Fugro CP ( after Withers et al, 1986 ) 27 2.13 Hughes SBPM Jetting System ( after Hughes, 1984 ) 28 2.14 Membrane Correction Curve for the Hughes SBPM 32 3.1 General Location of Research Sites 34 3.2 Typical CPTU Profile at McDonald Farm 6 3.3 Typical CPTU Profile at Lulu Is. - UBCPRS 40 3.4 Typical CPTU Profile at Langley Lower 232 43 4.1 Effect of Pressuremeter Insertion Method and Relaxation Time on Pressure Expansion Curves ( after Baguelin et al, 1978 ) 52 4.2 Comparison Between Dilatometer PQ and Penetration Pore Pressures from Piezoblade in Normally Consolidated and Lightly Overconsolidated Clays (after Lutenegger, 1988) ....54 viii LIST OF FIGURES ( CONT. ) Figure Page 4.3 Comparison Between Dilatometer PQ and Penetration Pore Pressures from Piezoblade in Overconsolidated Clays ( after Lutenegger, 1988) 54 4.4 Effect of Relaxation Time on FDPM Tests at Lulu Is. - UBCPRS 56 4.5a,b Comparison of FDPM and SBPM Tests at McDonald Farm 64 4.6a,b Comparison of FDPM and SBPM Tests at Lulu Is.-UBCPRS 66 4.7 Comparison of FDPM, SBPM and Dilatometer Lift-off Pressures 69 4.8 Comparison of FDPM and SBPM Practical Limit Pressures and Dilatometer P^ Values 71 4.9 Determination of Undrained Shear Strength using the Windle and Wroth Average Strength Method 74 4.10 Determination of the Stress-strain Curve using the Modified Arnold Type 1 Analysis 76 4.11 Determination of Undrained Shear Strength using the Houlsby Unloading Analysis 7 4.12 Comparison of Cone Bearing and FDPM Practical Limit Pressure 79 4.13 Hierarchy and Variation in Undrained Strength Ratio for Various Test Methods ( adapted from Wroth, 1984) 82 4.14 Shear Modulus Attenuation Curves in Cohesive Soils 84 4.15 Variation in (q^ - «"vo)Avo' with OCR at Onsoy ( after Wroth, 1988 ) 88 4.16 Values of G/Su Plotted Against OCR from CKQU DSS Tests on Three Clays ( after Ladd and Edgers, 1972 ) 90 5.1 Field Vane Undrained Shear Strength 95 5.2 Normalized Undrained Shear Strength from Field Vane 96 5.3 Proposed Reference Su For Lulu Is. - UBCPRS 97 5.4 FDPM and SBPM Undrained Shear Strength from Windle and Wroth Average Strength Method 99 ix LIST OF FIGURES ( CONT. ) Figure Page 5.5 SBPM Undrained Shear Strength from Arnold Curve Fitting Method 102 5.6 FDPM Undrained Shear Strength from Houlsby Unloading Method 103 5.7 FDPM and SBPM Pressuremeter Factor N - (PL - PQ)/SU REF vs Depth 105 5.8 FDPM and SBPM Pressuremeter Factor N - (PL - ^vo)/Su REF vs Depth 7 5.9 Cone Factor Nkt - (qt - <7vo)/Su j^p vs Depth 110 5.10 Cone Factor NAu - Au/Su R£F VS DEPTN 111 5.11 Comparison of Su using FDPM Factor N and Cone Factor Nkt 112 6.1 Unload-Reload, Gur, and Houlsby Unloading, G^, Shear Moduli vs Depth 116 6.2 Dynamic Small Strain Shear Modulus, Gmax, vs Depth 118 6.3 Gur/Gmax vs shear Strain at McDonald Farm 119 6.4 Gur/Gmax vs shear Strain at Lulu Is.-UBCPRS 120 6.5 Gur/Su REF and Houlsbv Unloading Ir vs Depth 122 6-6 Gmax/Su REF vs DEPTH 124 6.7 Gur/Su REF vs Snear Strain at McDonald Farm 126 6.8 GUR/SU REF vs Snear Strain at Lulu Is.-UBCPRS . ... 127 7.1 Stress History from Field Vane at Langley Lower 232 130 7.2 Variation in Gmax/Su with OCR at Langley Lower 232 132 7.3 Variation in ^O'^vo^vo' and ^t^vo^vo' with OCR at Langley Lower 232 137.4 FDPM KQ Values Obtained Using Empirical Method 134 X LIST OF FIGURES ( CONT. ~) Figure Page 7.5 SBPM KQ Values Obtained Using Empirical Method at McDonald Farm 135 7.6 Comparison of Dilatometer KD and FDPM KpM Values 137 xi ACKNOWLEDGEMENT I would like to thank my research supervisor, Dr. R.G. Campanella for his guidance during the course of this study. The helpful suggestions and assistance with data collection from my colleagues, Erick Basiw, Jim Greig, John Howie, John Sully, and Damika Wickremesinghe are much appreciated. The excellent technical support received from Art Brookes, Scott Jackson, Glen Jolly and Harald Schrempp is also acknowledged. A special thanks is extended to my wife, Leanne, whose support and encouragement throughout the duration of this research project has been much appreciated. The technical and financial assistance of Foundex Explorations Ltd. and the financial support provided by N.S.E.R.C. is gratefully acknowledged. 1 CHAPTER 1  INTRODUCTION In recent years, the in situ testing of soils has increasingly become emphasized as an important alternative and/or addition to laboratory or full scale tests. The purpose of this thesis is to analyze and interpret the performance of a relatively new in situ testing device, the cone pressuremeter. The cone pressuremeter consists of a 60 degree , 15 square cm. piezocone, and a pressuremeter of equal diameter to the cone situated a short distance behind the cone tip. The focus of this study is to interpret the results of full displacement pressuremeter (FDPM) tests performed as part of a cone pressuremeter (CP) sounding. The rational for the development of the cone pressuremeter is described below. The capabilities of the piezocone penetration test (CPTU) have been well documented (Campanella and Robertson,1988; Jamiolkowski et al,1985). The CPTU test is of particular value in providing a detailed soil profile. Furthermore, the evaluation of the flow and consolidation characteristics and a tentative evaluation of the stress history in cohesive soils can be made. The cone resistance can also be used to estimate to varying degrees of reliability the drained and undrained shear strength of both granular and cohesive soils. However, the CPTU test generally gives a poor estimate of soil stiffness. The pressuremeter test, in principle, will provide a better estimate of soil stiffness and strength than the CPTU test. Several different types of pressuremeters have been developed since Menard first 2 introduced the pressuremeter in 1954 and can be classified according to the insertion method used as shown in Table 1.1. Table 1.1 : Classification of Pressuremeters According to Method of Insertion (adapted from Huang and Haefele , 1988) 1 1 | Insertion Method Pressuremeter Type 1 1 | Reference | | Pre-bored Menard OYO LLT j Baguelin et al (1978) | j Suyama et al (1982) j | Self-bored Camkometer PAF | Wroth & Hughes (1973) | j Baguelin et al (1978) j | Push-in Stress Probe j Henderson et al (1979) j | Fyffe et al (1982) j | Full-Displacement FDPM j Hughes & Robertson(1985) j Cone Pressuremeter I Howie (1989) The Menard style probe is placed in a pre-bored hole and is expanded to provide a pressure-volume curve. Due to disturbance and stress relief in the soil surrounding the borehole, most Menard pressuremeter data is used in an empirical manner and is directly correlated to the performance of foundations. In an attempt to overcome the limitations created by soil disturbance, the self-boring pressuremeter (SBPM) was developed independently in France and England (Baguelin et al,1972; Wroth and Hughes, 1973) . The SBPM is slowly pushed into the ground as soil at the bottom 'of the cylinder is chopped up by a rotating cutter and flushed to the surface. When the SBPM is inserted with a minimal amount of soil disturbance, the capability exists to derive the soil stress-strain 3 behavior, the in situ horizontal stress and in some cases the consolidation characteristics of the soil. However, the SBPM test is costly to perform and takes highly skilled personnel to insert the probe with the minimum possible amount of soil disturbance. The push-in pressuremeter (PIP) or stress probe (Henderson et al,1979; Fyffe et al,1982) , developed primarily for offshore use, is a hollow open-ended pressuremeter with an end area ratio of 40 %. The probe is pushed a short depth below the bottom of a borehole creating a small but significant amount of disturbance. The FDPM test is performed in soil which has been substantially disturbed. However, the disturbance created is repeatable and is operator independent. Furthermore, results from the FDPM test can be directly correlated to additional data collected during the seismic cone pressuremeter sounding . In an offshore environment, the cone pressuremeter has practical advantages over the self-boring or push-in pressuremeter test. The SBPM test is difficult to perform offshore (Fyffe et al,1982) and the PIP test involves repeated cycles of drilling, removing drill rods and performing a pressuremeter test. The insertion of a cone pressuremeter into soil creates a large amount of disturbance and complex and dynamic stress and strain fields around the pressuremeter. The primary objective of this research is to interpret the results of the FDPM test in light of this problem and to assess the suitability of using the FDPM test to determine the undrained shear strength, shear modulus and to a lesser extent stress history and in situ horizontal stress of cohesive soils. Piezocone and seismic data obtained as part of the cone pressuremeter sounding are not comprehensively analyzed but where appropriate are used to supplement 4 the FDPM test results. Furthermore, whenever possible, the results of the FDPM test have been compared to SBPM, piezocone, dilatometer and field vane test results. 5 CHAPTER 2  EQUIPMENT AND TEST PROCEDURES Three pressuremeter probes were utilized for this study : the UBC Seismic Cone Pressuremeter (UBC SCP), the Fugro Cone Pressuremeter (Fugro CP) and the Hughes Self-Boring Pressuremeter (Hughes SBPM). This chapter describes the test equipment, data acquisition systems and the test procedures used for the three pressuremeters. These considerations are considered in detail for the UBC SCP but not for the two other probes. A more detailed description of the Fugro CP and the Hughes SBPM is given by Howie (1990). 2.1 The UBC SCP 2.1.1 Description of the UBC SCP The major components of the UBC SCP are shown in Fig. 2.1 and are described below. The probe begins with a piezocone having a 60 degree, .15 cm^ conical tip followed by a friction sleeve having a surface area of 225 2 cm . Built in load cells allow the near continuous measurement of end resistance ( qc ) and sleeve friction ( f ) . Two electric pressure transducers located just above the cone tip and friction sleeve allow pore pressures to be measured during cone penetration. The dissipation with time of the pore pressures generated can be monitored during halts in the penetration. Mounted just below the friction sleeve are two piezo-electric bender elements or accelerometers which are aligned vertically at 90 degree angles to each other. Two more accelerometers are mounted just below the pressuremeter body in the same manner. The 6 PO Electronics Pressuremeter (PM) PM Electronics Cone Electronics n Pressure Developer (PD) Piezocone Module — Adapter to 10 cm2 Cone Rod Controlled Change Volume / Change Time Pressure Transducer Pressure Transducer Three Strain Arms Two Accelerometers Direct Current Regulation, Amplification Two Accelerometers Two Pore Pressure Sensors Friction Sleeve ( 225 cm2 ) Bearing (15 cm2 ) 60 Degree Tip Temperature Slope Fig. 2.1 : Schematic of the UBC SCP 7 accelerometers are used to obtain a seismic profile of the soil using the downhole seismic technique ( Rice , 1984 ). To obtain reliable and consistent CPTU data, the piezocone should be properly be calibrated and saturated and standardized test procedures should be used. Robertson and Campanella (1986) provide a comprehensive guideline to piezocone equipment, test procedures and data reduction. The center of the pressuremeter is located 1.34 m behind the cone tip. The core of the pressuremeter is a 39 mm diameter hollow cylinder with threads on either end. A pressure transducer is mounted in the pressuremeter core and pressure developer . Three vertically aligned strain arms are mounted in shallow channels cut in the pressuremeter core at 120 degree spacings. The strain arms are straight metal strips attached to the cone at one end to form a cantilever beam. Arm contact plates, which follow the membrane expansion, are connected to the free end of the metal strip. Two different designs of arm contact plates and methods of attaching the plate to the metal strip were used ( Fig. 2.2). The first or "old" design attached the 5 mm wide arm contact plate on top of the end of the metal strip. This proved to be a problem when the pressuremeter was fully deflated. Vertical and horizontal forces imposed on the contact plates due to soil and water stresses caused the ends of the metal strip to "bottom" out in the channel cut in the pressuremeter core. This is thought to have generated a moment at point 0 ( Fig. 2.2 ) with the end result being a voltage output from the strain gauge on the metal strip indicating an apparent outward deflection of the strain arm. The new design allowed the arm contact plates to "float" on the end of the metal strip, the point of contact being the rounded edge of the 8 Arm Cover Plate SIDE VIEW SIDE VIEW Screw NEW DESIGN Not to Scale Metal Strip ( Cantilever Beam ) FRONT VIEW F OLD DESIGN Not to Scale FRONT VIEW Metal Strip ( Cantilever Beam ) Fig. 2.2 : UBC SCP Strain Arm Design 9 screw shown in Fig. 2.2. Vertical and horizontal forces cause the arm contact plate housing to "bottom" out instead of the metal strip. This change solved the problem of apparent outward deflections of the strain arms when the pressuremeter was fully deflated. The effect of the different arm designs on the lift-off stage of the pressuremeter pressure-displacement curve is shown in Fig 2.3. The change in strain arm design also seems to affect the initial stages of the corrected pressuremeter expansion curve . For tests performed with the old strain arm design, a small but prevalent bump in the corrected pressuremeter expansion curve is found between 0 and 4 % cavity strain or radial displacement ( e - AR/RQ ). The new strain arm design appears to reduce or eliminate the small bump ( for comparison purposes, a complete set of pressuremeter expansion curves are found in appendices I to III ). Other causes for the small bump in the pressuremeter expansion curve are discussed in section 2.1.3 Two natural rubber membranes, each with an average thickness of 1.2 mm are attached to the pressuremeter body using tapered metal rings and retaining nuts. Protecting the membrane is a Chinese lantern made of stainless steel metal strips. The ends of the slotted strips fit over a nut with raised nipples and are held in place by a tapered metal ring. The" slots in the metal strips allow the lantern to move freely during membrane inflation and deflation. The exact diameter of the pressuremeter with two membranes and lantern strips was difficult to determine. An average diameter of 43.6 mm was obtained when clamps were used to compress the lantern around the pressuremeter body. This would suggest that the probe is slightly undersized since the rest of the UBC SCP probe has a diameter of 44 mm. Although the length of the 10 UBC SCP 300 OLD ARM DESIGN r T 0.1 0.2 DEFLECTION Fig. 2.3 : Effect of Different Strain Arm Designs on the Lift-off Stage of a Pressure-Displacement Curve 11 pressuremeter core is 385 mm, the length of the membrane which is free to inflate is 220 mm. This leads to a L/D ratio of 5. The pressuremeter is inflated with silipon oil using a downhole pressure developer. The 83 cm long pressure developer can generate pressures as high as 6900 kPa ( 1000 psi ) using a piston ball screw driven by an electric motor. Since a closed system is used, air in the oil going into solution, a small leak in the pressuremeter or backlash of the ball screw in the fully retracted position will all create negative pressures. The tests shown in Fig. 2.3 indicate at the beginning of the tests, negative pressures of 20 to 40 kPa existed. This range is typical of the negative pressures obtained at the beginning and end of tests performed using the UBC SCP. If the pressure developer ball screw is held in the fully retracted position for an extended period of time, the negative pressures tend to dissipate. To reduce the amount of air going into solution, the oil for the pressuremeter was first placed under vacuum to remove as much air as possible. o The pressure developer is attached to 10 cm area cone rods using an adapter enabling the probe to be pushed using the UBC In Situ Testing truck which is described in detail by Campanella and Robertson (1981). The UBC SCP probe has been successfully pushed to depths greater than 30 m and through soil layers with end bearing resistances greater than 200 bar. 2.1.2 The UBC SCP Data Acquisition System The UBC SCP has the capability to collect three different types of data; piezocone, pressuremeter and seismic. Three separate data 1 2 acquisition systems were used with the UBC SCP as shown by the schematic layout of the entire system shown in Fig. 2.4 Piezocone data is collected using the Hogentogler field computer (FCS), a surface 12 bit digital data acquisition system. The piezocone is designed so that the analog signals which are amplified downhole are compatible with the Hogentogler FCS. Data is stored in a magnetic bubble for later downloading to a microcomputer and is also immediately printed. A microcomputer based system developed at UBC is used to collect and process pressuremeter test data. The UBC data acquisition (DAS) consists of an IBM PC compatible microcomputer and analog to digital (A/D) converter. The microcomputer uses an Intel 8088 microprocessor card and a 8087 math coprocessor. Two multifunction I/O ( input/output) cards provide 512 KB of memory, two RS232 serial ports and two parallel ports. Two half height 360 KB floppy drives are used for data storage. A Data Translation DT2801-A 12 bit A/D converter board is used for analog to digital conversion. The analog signals are converted to a 12 bit representation of their voltage which means the voltages are represented by 4096 states ( 2 raised to the 12 th power ) . This represents an analog output with resolution equal to 0.024 % of the selected analog input range. The DAS can provide data conversions for up to 8 channels. The data sampling rate is user selectable with the maximum rate being equal to .4 seconds. Data sampling does not take place when the contents of a buffer are being written to a disk. For the first few tests performed with the UBC SCP this created a problem since the contents of a buffer were occasionally written to the disk at critical 13 Wcolet 40S4 16 tilt Digital Oscilloscope Hogentogler Field Computer IBM PC Compatible Microcomputer fi DT2801 12 bit A/D Converter J— Display Monitor Keyboard Printer Analog Signals Interface Unit Pressuremeter, Seismic or Cone Mode If- I. Strip Chart Recorder 12 V DC Power Supply for PD Motor Trigger Box Seismic Source fl K3 j Depth E tooder +/- 15V DC Power Supply for PM & Cone Electronics Hydraulic Lood Volve Switch Switch Reaction Cylinders Loading Head I UBC SCP Probe Fig. 2.4 : Schematic Layout of the UBC SCP Data Acquisition System 0 14 times during a test, Eg. at lift-off and during an unload-reload loop. This problem was solved by creating a larger buffer and writing to the disk at non-critical times. Seismic shear waves are generated by striking a metal pad, weighted to the ground, with a sledge hammer. Seismic wave traces are recorded by a Nicolet 4094 digital oscilloscope with 16 bit analog to digital signal resolution. This unit has very accurate timing capability and a trigger delay capacity. Data is stored on floppy disks. Two power supplies are needed for the probe : a 12 volt direct current supply for the pressure developer motor and a +/- 15 volt direct current power supply for the pressuremeter and cone electronics. 2.1.3 Test Procedures for the UBC SCP The calibration of strain arms using a micrometer and pressure transducers using a dead-weight pressure tester was done regularly. A typical strain arm calibration is shown in Fig. 2.5. Both the strain arm and pressure transducer calibrations showed virtually no hysteresis or non-linearity. The slope from a linear regression best fit line is used to convert strain arm data to engineering units. Before the beginning of each cone pressuremeter sounding, the probe was placed in a 44 mm diameter steel split cylinder and zeros or reference voltage outputs for the pressure transducers and strain arms were obtained. Zeros were found to be relatively stable when subject to small temperature fluctuations. As an extra precaution, the probe temperature was allowed to come into equilibrium with the outside air temperature. Since all tests included in this study took place between 15 Fig. 2.5 : Typical Strain Arm Calibration for the UBC SCP 16 December and April, it is likely that the difference between the ground and air temperature was less than 5 degrees Celsius. The membrane correction curve was determined by inflating and deflating the pressuremeter with the Chinese lantern attached in air ( Fig. 2.6 ). The probe was inflated at approximately the same rate as subsequent tests in the ground. The shape of the membrane correction curve was consistent with no apparent softening under prolonged use. Furthermore, the correction curve was not altered when the maximum strain achieved during expansion was changed. The membrane correction expansion curve for cavity strains between 0 and 4 % is quite steep. The steepness of the air inflation curve is a drawback when it is used to correct pressuremeter tests since a small shift in zeros for the strain arms will affect the shape of the corrected pressuremeter expansion curve. This effect could be a contributing factor to the small but prevalent bump found in pressure expansion curves at cavity strains between 0 and 4 %. For cavity strains greater than 4 %, the pressure increases only slightly. Unfortunately, a pressure correction of approximately 50 kPa can be a significant proportion of the total expansion pressures obtained during a test in soft cohesive soils at shallow depths. In order to correct a pressuremeter test, the air inflation and deflation curves were fitted using a hyperbolic equation of the form : € P - Q + 2.1 a + be The parameters a and b and the pressure axis intercept Q are found by choosing 3 points from the pressure versus cavity strain curve. In 17 UBC SCP 10/12/87 Langley Lower 232 Air Inflation Cavity Strain [%] + Avg. of Arms 1 -2-3 Fig. 2.6 : Membrane Correction Curve for the UBC SCP 18 general Q was close to zero for all membrane correction expansion curves. All pressuremeter tests performed with the UBC SCP probe were run using a quasi-constant strain rate. An example of the cavity strain rate during a representative test is shown in Fig. 2.7. A summary of the strain rates used for all pressuremeter tests can be found in appendices I through III. A maximum cavity strain of 27 % can be achieved. 2.1.4 UBC SCP Compliance The UBC SCP system compliance affects both pressure and strain measurements and is caused primarily by compression of the lantern strips, creep and compression of the membrane and air in the oil going into solution. Figures 2.8a,b show the results of a pressuremeter test run inside a 44 mm diameter steel split cylinder. A membrane correction curve is also included in Fig. 2.8b for comparison purposes. Below approximately .7 % cavity strain ( AR - .15 mm ), very little compression of the lantern strips is taking place, a result of the probe being slightly undersized. For strains greater than .7 %, a considerable amount of lantern compression occurs. From pressuremeter expansions in the steel cylinder without the lantern strips attached, it appears that very little membrane compression occurs for pressures less than 500 kPa. For a pressuremeter test performed in a saturated cohesive soil, it is extremely difficult to assess the effect of lantern compression on a pressuremeter test. It is likely that water will rapidly flow in behind the lantern strips as expansion proceeds therefore making the compliance of the lantern strips dependent on the effective stress state around the pressuremeter. This is an important assumption since it is apparent from 19 c E 3 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 -1 -0 UBC SCP 3/4/87 Lulu Is.-UBCPRS Depth=6.35 m EXPANSION UNLOAD-RELOAD LOOP CONTRACTION STRAIN RATE - AVERAGE VALUES FOR 7 DATA POINTS -T— 40 —r-80 —I— 120 160 —I— 200 240 TIME ( sec ) Fig. 2.7 : Typical Strain Rate Used for a UBC SCP Test 20 2000 UBC SCP 4/12/87 Inflation in 44 mm Dio. Split Cylinder 1500 o a. 3 i. 1000 500 -EXPANSION • CONTRACTION Cavity Strain [X] Avg,. of arms 1—2—3 a 500 UBC SCP 4/12/87 Inflation in 44 mm Dio. Split Cylinder 400 -300 & 3 c a. •o e TJ E o o c => 200 -100 -EXPANSION IN SPLIT CYLINDER • EXPANSION IN AIR -100 Cavity Strain [X] Avg. of arms 1-2-3 Fig. 2.8a,b Results of a UBC SCP Test Inside a 44 mm Diameter Steel Cylinder 21 Fig. 2.8b that a pressure drop due to a change from total to effective stresses could cause a significant reduction in compliance for pressures less than approximately 200 kPa. If the compression of the lantern strips are governed by effective stresses, the compliance will approximately be constant for an undrained test in a cohesive soil. The effect of air going into solution and membrane creep can be observed by rapidly inflating the pressuremeter in the steel cylinder to a set strain and then holding the strain constant. A rapid pressure decrease is initially observed, the rate becoming slower with time. The magnitude of the pressure decrease for a constant time period is proportional to the initial pressure reached. The effects of air going into solution and membrane creep are felt to be of minor importance for the pressures reached during tests performed for this study. Due to the complex and indeterminate nature of compliance, no attempt was made to correct pressuremeter tests for compliance. A pressuremeter design incorporating a pore pressure transducer on the membrane would allow for a more accurate assessment of the effects of compliance. 2.2 The Fugro CP The prototype Fugro CP used for this study was built by Cambridge In situ in conjunction with Fugro Geotechnical Engineers B.V. Figure 2.9 shows the components of the Fugro CP. Future versions of the cone pressuremeter will use a 15 cm piezocone instead of a dummy cone. The details of the pressuremeter component of the Fugro CP are shown in Fig. 2.10. The distance between the center of the membrane and the conical 22 PUSH HEAD • n /-"^ w ELECTRO/HYDRAULIC HOSE CONE ROOS CONDUCTING HOSE ' STANDARD CONE ROD CONE ROD ADAPTOR AMPLIFIER HOUSING CONTRACTION RING ' PRESSUREMETER MODULE CONTRACTION RING CONE SPACER DUMMY CONE CONTROLE UNIT '•READ OUT Fig. 2.9 : Schematic of the Fugro CP ( after Withers et al, 1986 ) 23 CONTRACTION RING CHINESE LANTERN MEMBRANE CLAMP RING MEMBRANE ARM COVER SLEEVE STRAIN GAUGED SPRING 3 STRAIN SENSING ARMS AT 120° SPACING INSTRUMENT BODY MEMBRANE MEMBRANE CLAMP RING CHINESE LANTERN CONTRACTION RING CONNECTION TO CONE SPACER AND CONE CONNECTION TO AMPLIFIER SUB c 8 O «-< E £ s 43.7 mm Fig. 2.10 : The Pressuremeter Component of the Fugro CP ( after Withers et al, 1986 ) 24 tip has a minimum value of 930 mm. This distance can be increased through the use of spacers. The outside diameter of the Fugro CP is 43.7 mm which corresponds o to the dimensions of an almost 15 cm cone. The L/D ratio is 10.3. The pressuremeter measures the inflation pressures and the cavity strain or radial displacement at 120 degree spacings using 3 strain arms. The strain arms, which consist of a pivoted arm and strain gauged spring, are similar in design to the ones used in the Cambridge SBPM . The pressure capability of the pressuremeter is 10 MPa while the cavity strain capacity is 50 %. Nitrogen gas was used to inflate the probe with tests being performed in a quasi-strain controlled manner by steadily turning the pressure regulator to maintain an approximately constant inflation rate. Two regulators were used : a 14 - 826 kPa (2 - 120 psi) regulator for softer soils and a 34 to 3100 kPa (5 - 450) psi regulator for tests requiring a larger range. The analog signals were amplified downhole and transmitted to the surface through an electrical cable. Both the electrical cable and the inflation hose were placed inside standard 20 tonne cone rods of 16 mm inside diameter. The use of a XYY strip chart recorder allowed the analog monitoring of strain and pressure. A 12 bit analog to digital data translation board was added to a standard portable COMPAQ microcomputer. Digital output was stored on floppy disks. A scanning range of 0 to 1.25 V was used resulting in a resolution of close to 0.3 mV. The minimum time between data points was one second. The pressure transducer and strain arms were calibrated using a dead weight pressure tester and micrometer respectively. A typical strain arm calibration is shown in Fig. 2.11. Since the strain arm data 25 3.00 E E UJ O 2.00 CO Q o: UJ t3 1.00 o ct: o 0.00 FUGRO CP STRAIN ARM CALIBRATION T—I—I—i—I—I—r^~i—i—i—i $fx>s*i—r ***** ARM 00000 ARM 111 111 ARM A A AAA ARM 00000 ARM IIIII ARM EXPANSION 1 CONTRACTION EXPANSION CONTRACTION EXPANSION CONTRACTION —0.1 0 LINEAR REGRESSION BEST FIT LINE ARM 1 DISTANCE - 9.700»OUTPUT - 0.3213 ARM 2 DISTANCE - 9.7B9»0UTPUT - 0.1387 ARM 3 DISTANCE - 9.679»0UTPUT + 0.9333 1 [—T 0.00 0.10 TRANSDUCER 0.20 OUTPUT -i—r-0.30 Volts ) i—r 0.40 Fig. 2.11 : Strain Arm Calibration for the Fugro CP 26 was converted using a linear regression best fit line, some error may have been introduced due to the hysteresis and initial non-linearity. Initial zeros were taken before each pressuremeter test. Pressuremeter tests were corrected using a membrane correction curve similar to the one shown in Fig. 2.12. For this particular correction curve the lift off pressure is 27 kPa and the maximum hysteresis is approximately 10 kPa. The membrane correction at 20 % radial displacement is approximately 100 kPa which is twice as much as the correction obtained with the UBC SCP. 2.3 The Hughes SBPM The Hughes SBPM was built by Dr. J.M.O. Hughes and except for a few mechanical differences is similar to the SBPM built by Cambridge In Situ. The major difference is that the Hughes SBPM employs a jetting device to remove soil and advance the probe as opposed to the traditional method of first cutting up the soil using a rotating cutter and then flushing the soil to the surface. Figure 2.13 shows how the Hughes SBPM jetting system works. Water or mud is pumped down the drill rods and out the jetting ports just inside the cutting shoe. An advantage of this system is that the probe can be inserted in to the soil using one rod as opposed to the double rod system used with the Cambridge SBPM. A disadvantage with the jetting system is that certain soils such as stiff or sticky soils will not break up easily under water and therefore the flushing system will tend to clog. The Hughes SBPM has an outside diameter of 74 mm and a L/D ratio of 6. The total gas pressure inside the probe and pore pressures at two 27 Fig. 2.12 Membrane Correction Curve for the Fugro CP ( after Withers et al, 1986 ) 28 Drilling Mud Fig. 2.13 : Hughes SBPM Jetting System ( after Hughes, 1984 29 locations are measured using pressure transducers while the displacement is measured by 3 strain arms at 120 degree spacings. The analog signals are transmitted to the surface through an electrical cable. Several different data acquisition systems and test procedures were utilized with the Hughes SBPM. For tests performed at McDonald Farm, the pressure and strain values were monitored using a digital volt meter plugged into the control box. Using a XYY strip chart recorder simultaneous analog plots of two of the three displacement sensors and total pressure were also made. During a standard test the reading from the pressure and strain sensors were recorded manually after each increase in pressure. Using this procedure, the interval between successive pressure increments was greater than 30 seconds which resulted in an average test taking about half an hour to complete. This corresponds to an average expansion cavity strain rate of roughly 10 %/min. Several quick tests were performed in which no manual reading were taken. Instead the analog recordings from the strip chart were later digitized. The quick test took about 2 minutes to perform resulting an average expansion strain rate of roughly 1 %/min. For tests performed at the Lulu Is.-UBC Pile Research Site (PRS) , the analog signals were amplified downhole and transmitted to the surface using a time division multiplexed signal. Using this system 8 channels could be output every 1 second. The analog signals were converted to digital output using a 8 bit A/D converter in the control box. The digital output was simultaneously plotted on a microcomputer computer screen and output to a floppy disk. Tests were performed in a quasi-strain controlled manner by steadily turning the pressure regulator to maintain an approximately steady inflation rate. 30 All Hughes SBPM tests were performed using a lightweight drill rig anchored into the ground. Such variables as jetting pressure, velocity of the jetting fluid, location of the jetting ports and the rate of advance should be carefully monitored and controlled if possible. The drilling parameters were monitored at McDonald Farm and are shown in Table 2.1. Table 2.1 : Test Depth and Drilling Parameters for the Hughes SBPM at McDonald Farm ( adapted from Hughes, 1984 ). j Depth | ( m ) | Rate of | Penetration 1 ( m/min ) j Flow Rate 1 ( L/sec ) Mud Pump Pressure ( kPa ) | Ram Force | | ( kN ) | | 16.75 | 1.0 160 | 6.4 | | 17.75 | 0.3 | 0.47 830 1 8.5| 18.76 1 0.5 | 0.2 1030 | 6.5 | | 19.76* | 0.14 | 0.15 690 8.4 j | -20.76 | 0.33 | 0.64 620 | 8.4 | | 21.76* | 0.32 | 0.20 480 I 8.4| 22.76 I 0.27 | 0.18 550 1 8.4 | | 23.76* | 0.34 | 0.12 480 | 8.1| 24.76* | 0.21 0.16 620 1 8.4 | 25.76 j 0.17 | 0.17 480-690 8.4 - Quick tests performed in approximately 2 minutes. The jetting ports were set 10 mm behind the bottom of cutting shoe for all tests. No comparable records were kept for the tests at Lulu Is.-UBCPRS. However, the mud pump pressure and ram force were periodically checked to try to ensure that the insertion process was creating as little soil disturbance as possible. Nevertheless, excessive mud pump pressures and/or ram forces indicative of clogging of the SBPM cutting shoe occurred several times each time forcing the probe to be retrieved for 31 cleaning. The fibrous organic nature of the soil at Lulu Is.-UBCPRS appeared to make the self-boring process more susceptible to clogging. A membrane correction curve similar to the one shown in Fig. 2.14 was used to correct all Hughes SBPM data. The applied pressure increases monotonically as the strain increases and is subject to only a small amount of hysteresis when unloaded.. 32 HUGHES SBPM 16/2/87 Lulu Is. - UBCPRS Air Inflation 100 -i 90 -80 -70 -60 -0 2 4 6 8 10 12 14- 16 18 20 CAVITY STRAIN (%) Avg. of Arms 1 -2-3 Fig. 2.14 : Membrane Correction Curve for the Hughes SBPM 33 CHAPTER 3  TEST SITES AND FIELD PROGRAMME 3.1 Scope The field programme was conducted at three soil sites in the Lower Fraser Valley where cohesive soils predominate as located in Fig. 3.1. The focus of this report is to present and interpret the results of FDPM tests performed as part of a cone pressuremeter sounding. Whenever possible, the FDPM test results have been compared to the following in situ tests : 1. Self-Boring Pressuremeter Test ( SBPMT ) 2. Piezocone Penetration Test ( CPTU ) 3. Down-hole Seismic Cone Penetration Test ( SCPT ) 4. Flat Dilatometer Test ( DMT ) 5. Field Vane Test ( FVT ) All tests included in this study except SBPM tests conducted at McDonald Farm were performed by the UBC In Situ Testing Group. The SBPM tests at McDonald Farm were conducted by Dr. J.M.O. Hughes. 3. 2 Site Descriptions  3.2.1 McDonald Farm McDonald Farm is located at the northern edge of Sea Island in the municipality of Richmond. The island is contained by a system of dikes to protect against flooding from the river. The site has a ground elevation of 1.6 m ( Geodetic Datum ) and is reasonably level. The water table is approximately 1 m below the ground surface and is subject to tidal fluctuations. Fig. 3.1 : General Location of Research Sites 35 McDonald Farm is within the post-glacial Fraser River delta ( Fig. 3.1 ). The marine deltaic sediments of Sea Is. have been forming since the retreat of the Fraser Glaciation ice sheets some 8000 - 10000 years ago ( Blunden, 1975). The present thickness of the deltaic deposits are roughly 200 m and have formed on basal layers undergoing isostatic rebound at a rate which is greater than the post-glacial marine transgression. The surficial deposits of Sea Island consist of deltaic distributary channel fill and overbank deposits which overlie post glacial estuarine and marine sediments ( Armstrong, 1978). A representative CPTU profile from McDonald Farm is presented in Fig 3.2. The time for 50 % dissipation of pore pressure measured directly behind 2 a 10 cm area cone tip from several CPTU soundings is also included. The findings in this report are limited to the clayey silt between 15 and 30 m. The cone bearing, qt, in Fig 3.2 has been corrected for unequal end area ratios ( Campanella and Robertson, 1981). Both the cone bearing and pore pressure profiles increase linearly with depth suggesting a normally consolidated soil. The soil properties and in situ tests performed at McDonald Farm are given in Tables 3.1 and 3.2. The location of the individual in situ tests performed are included in appendix VI. The permeability value in Table 3.1 was measured by a variable head inflow test using the BAT Groundwater Monitoring System built by BAT Envitech Inc ( Petsonk, 1985 ). UBC I M SI to Location! McDONALD FARM On Si to Loo MFB5-4 SITU XE CPT Doto i 28/09/85 Cono Usedi UBC #6 STD PP T I MG Pago Noi 1 / 1 Commantsi PORE PRESSURE U («. of »oter> 0 100 10 20 30 V -I 1——1 L. SLEEVE FRICTION <bcr) 0 .5 CONE BEARING Ot (bar) FRICTION RATIO Rf tt) 0 5 - 10 DIFFERENTIAL P.P, RATIO AU/Ot -.2 0 .8 0 INTERPRETED PROFILE •sow 20 30 r LOOM to Dsnss Coons Sand Soms 10-j Fins Sand 2D 30 Soft Organic Slty Clay Fins Sand Soms SfK Soft N.C. Claysy Slit Depth Increment Fig. 3.2 . 025 m Max Dopth i 2B. 95 m Typical CPTU Profile at McDonald Farm 134 158 384 179 2BS 383 133 136 163 IBS 120 360 270 330 101 37 Table 3.1 : Soil Properties at McDonald Farm Specific Gravity : 2.8 Natural Water Content (%) : Range 23-40 Average 34 Liquid Limit (%) : Range 25-42 Average 35 Plastic Limit (%) : Range 22-25 Average 24 Plasticity Index (%) : Range 3-20 Average 15 Sensitivity ( field vane ) : Range 2-7 Average 5 Coef. of Consolidation (cm2/s) : Range 0 012-0.018 ( 2 oedometer tests ) Average 0.015 Permeability (cm/s) 4*10-7 ( 1 BAT inflow test @ 21.5 m ) 0 38 Table 3.2 In Situ Tests Performed at McDonald Farm | No. j In Situ Test | Name In Situ j Date j Device 1 | 1 j Seismic Cone Pressuremeter UBC SCP-11 UBC SCP | 27 JAN 87 | 1 2 | Cone Pressuremeter FUGRO CP-12 FUGRO CP | 7 NOV 85 j 1 3 j Self-Boring Pressuremeter SBPM-1 SBPM j 18 OCT 83 j 1 4 | Piezocone Penetration CPTU-1 UBC * 1 15 APR 81 j j 5 | Piezocone Penetration CPTU-2 UBC 4 I 23 JULY 82 | 1 6 | Piezocone Penetration CPTU-3 UBC 4 1 4 AUG 82 j | 7 | Piezocone Penetration CPTU-4 UBC 6 I 26 JAN 84 | 1 8 | Piezocone Penetration CPTU-5 UBC 8 I 26 SEPT 85 j 1 9 | Piezocone Penetration CPTU-6 ; UBC 26 SEPT 85 j 1 10 | Piezocone Penetration CPTU-7 HOG SUPER| 25 SEPT 86 | 1 11 | Piezocone Penetration CPTU-8 UBC 8 I 25 SEPT 88 | 1 12 | Seismic Cone Penetration SCPT-l(Acc) | UBC 8 ] 14 MAY 85 | 1 13 | Seismic Cone Penetration SCPT-2(Geo) UBC 6 ! 17 OCT 85 j 1 14 | Seismic Cone Penetration SCPT-3(Acc) UBC 8 8 JAN 86 | 1 15 | Seismic Cone Penetration SCPT-4(Acc) | UBC 8 16 OCT 86 | 1 16 | Seismic Cone Penetration SCPT-5(Geo) | UBC 6 14 MAY 86 j 1 17 | Seismic Cone Penetration SCPT-6(Geo) I HOG SUPER 2 JULY 87 | 1 18 j Flat Dilatometer DMT-1 | MARCHETTI 14 MAY 80 j 1 I9 | Flat Dilatometer DMT-2 | MARCHETTI 2 OCT 86 | | 20 j Field Vane FVT-1 | GEONOR 27 SEPT 83 | 1 21 j Field Vane FVT-2 GEONOR 29 SEPT 83 1 - No seismic or piezocone data obtained 2 - No piezocone data obtained Acc - Accelerometer Geo = Geophone HOG SUPER => Hogentogler Super Cone SBPM = Hughes SBPM 3.2.2 Lulu Island UBC Pile Research Site The Lulu Is.-UBC Pile Research Site (PRS) is located at the eastern end of Lulu Is. at the junction of Boundary and Dike Roads. A group of six piles installed by the British Columbia Ministry of Transportation and Highways have been used to study the axial and lateral load behavior of piles at the UBCPRS. Davies ( 1987 ) presents the results of this study. The gently sloping site is covered by 2 to 4 m of heterogeneous fill. This fill was removed and replaced with clean river sand in the 39 general area of the pile group to facilitate pile driving and in situ testing. The water table is approximately 1.5 m below the ground surface. The Lulu Is.-TJBCPRS is located within the post-glacial Fraser River delta. The surficial deposits to a depth of 15 m consist of peat and organic clayey silt deposited in swamp or marsh environment. The organic sequence is underlain by a sand layer, representing a higher energy depositional environment possibly being a former channel bank of the Fraser River. A representative CPTU profile of the top 15 m of soil is shown in Fig. 3.3. The time for 50 % dissipation of pore pressure measured behind o a 10 cm area cone tip from several CPTU soundings is also included. The low cone bearing values and high friction ratios between approximately 2.5 and 5.0 m depth suggest and organic clayey silt with some peat layers. A water content of 269 % and an organic content of 27 % by weight was obtained for a soil sample from 3.0 m depth. Below a depth of 5.0m the cone bearing increases in an approximately linear fashion with depth suggesting a normally consolidated soil deposit. Between 11.5 and 13.5 m , several small spikes in the cone bearing profile suggest the presence of perhaps slightly more dense silt or discontinous silty fine sand layers. The material properties of the organic clayey silt layer is given in Table 3.3 and the in situ tests performed at Lulu Is.-UBCPRS are given in Table 3.4. The locations of the individual in situ test performed are included in appendix VI. UBC I M SITU T "EST I MG Site Location! Lulu Is. UBCPRS . CPT Data i 09/10/86 Pago Noi 1/2 On Si to Loci PLTSCPT2 Cona Usadt Hog Supar StdPP CoRimantsi CPT3 PORE PRESSURE SLEEVE FRICTION CONE BEARING FRICTION RATIO DIFFERENTIAL P.P. INTERPRETED Dopth Increment • .025 m Max Dopth i 16 m Fig. 3.3 : Typical CPTU Profile at Lulu Is. - UBCPRS 41 Table 3.3 : Soil Properties at Lulu Is.-UBCPRS Specific Gravity : 2.7 Natural Water Content (%) : Range 64-86 Average 69 Liquid Limit (%) : Range 49-90 Average 64 Plastic Limit (%) : Range 38-50 Average 42 Plasticity Index (%) : Range 10-47 Average 21 Sensitivity ( field vane ) : Range 3-19 Average 11 Coef. of Consolidation (cm2/s) : Range 0 032-0.070 ( 2 oedometer tests ) Average 0.05 Table 3.4 : In Situ Tests Performed at Lulu Is.-UBCPRS No. In Situ Test Name In Situ Device Date 1 Seismic Cone Pressuremeter UBC SCP-11 UBC SCP 3 APR 87 2 Seismic Cone Pressuremeter UBC SCP-2 UBC SCP 8 JAN 88 2 Self-Boring Pressuremeter SBPM-1 SBPM 11 FEB 87 4 Self-Boring Pressuremeter SBPM-2 SBPM 19 FEB 87 5 Piezocone Penetration CPTU-1 UBC 6 13 JUNE 84 6 Piezocone Penetration CPTU-2 UBC 6 13 AUG 85 7 Piezocone Penetration CPTU-3 HOG SUPER 9 OCT 86 8 Piezocone Penetration CPTU-4 HOG SUPER 31 OCT 86 9 Seismic Cone Penetration SCPT-l(Acc) UBC 8 8 OCT 86 10 Flat Dilatometer DMT-1 MARCHETTI 23 AUG 85 11 Flat Dilatometer DMT-2 MARCHETTI 29 AUG 85 12 Field Vane FVT-1 NILCON 31 OCT 86 1 - No seismic or piezocone data obtained 3.2.3 Langley Lower 232 The Langley Lower 232 site is located at the 232 street exit of the Trans Canada Highway in Langley. The site is north of the highway and 42 west of the overpass. The water table is approximately 1 m below the gently sloping ground. The site is located at the western extent of the Fort Langley Formation. The Quaternary formation consists of marine silts and clays deposited during the glacial regressions and are occasionally interbedded with sand layers. Underneath the silts and clays are dense glaciomarine sands and gravels. The fine grained soils at the surface are overconsolidated due to desiccation. A representative CPTU profile of the Lower Langley site is shown in Fig. 3.4. An over consolidated surface crust roughly 3 m thick is underlain by a relatively homogeneous silty clay deposit. The sharp increases in cone bearing and negative pore pressures measured between 13 an 16 m indicate the presence of several thin sand layers. An interlayered silty clay and sand unit is found below 23 m. The material properties of the silty clay layer are given in Table 3.5 and the in situ tests performed at Langley Lower 232 are given in Table 3.6. The locations of the individual in situ tests performed are included in appendix VI. UBC IM SITU TESTING Site Location! LANGLEY On SI to Loci LOWER 232 CPT Date • J1-J9-B7 18i 15 Cona Usedi HOG SUPER STO u Pago Noi 1/1 Comment*! C77-8713 5MMFILT PORE PRESSURE SLEEVE FRICTION U (a. of »at«r) (bar) 0 100 0 .3 CONE BEARING Ot (bar) 10 20 30 FRICTION RATIO Rf (X) 40 0 5 DIFFERENTIAL P.P. RATIO AU/flt -.2 0 .6 Ol—I—1—'—'—| 0 INTERPRETED PROFILE • ID • 2D 30* Depth Increment i .025 m Max Depth i 29.85 m Fig. 3.4 : Typical CPTU Profile at Langley Lower 232 SlHy Cloy O.C. near Surfocs Occasional Sand Lsnss 44 Table 3.5 : Soil Properties at Langley Lower 232 Specific Gravity 2.8 Natural Water Content (%) : Range -Average 45 Liquid Limit (%) : Range -Average 40 Plastic Limit (%) : Range -Average 20 Plasticity Index (%) : Range -Average 19 Sensitivity ( field vane ) : Range 2-19 Average 11 Coef. of Consolidation(cm2/s) : Range .0002-.0003 ( 2 oedometer tests ) Average .00025 Permeability ( cm/s ) : 8*10-8 ( 1 BAT inflow test @ 7.3 m ) Table 3.6 : In Situ Tests Performed at Langley Lower 232 | No. j In Situ Test J Name In Situ j Device 1 Date j 1 1 | Seismic Cone Pressuremeter UBC SCP-1 UBC SCP | 10 DEC 87 | 1 2 | Piezocone Penetration CPTU-1 | UBC 4 | 24 NOV 83 | 1 3 | Piezocone Penetration CPTU-2 UBC 6 | 6 JULY 84 j 1 | Piezocone Penetration CPTU-3 j HOG SUPER j 7 NOV 87 | 1 5 | Piezocone Penetration CPTU-4 UBC 7 7 NOV 87 j 1 9 | Seismic Cone Penetration SCPT-l(Acc) j HOG SUPER j 7 NOV 87 | 1 io | Flat Dilatometer DMT-1 j UBC DMT j 20 JUNE 84 j 1 11 | Field Vane FVT-1 NILC0N | 17 NOV 83 j 1 12 j Field Vane FVT-2 j NILCON j 11 JAN 84 | 1 13 j Field Vane FVT-3 j NILCON j 20 JAN 84 j 1 14 | Field Vane FVT-4 | NILCON j NOV 83 | 15 | Field Vane FVT-5 NILCON 7 NOV 87 CHAPTER 4 THE INTERPRETATION OF THE PRESSUREMETER TEST 4.1 Analytical Approaches to the Pressuremeter Test An advantage of the pressuremeter test is that it approximates the plane strain expansion of an infinitely long cylinder, a problem which has well defined elastic and plastic solutions. One of the first solutions to be applied to this problem was by Bishop, Hill and Mott (1945) who developed a theory to calculate the pressure required to inflate a sphere or cylinder in an elastic-plastic strain hardening material. Menard initially attempted to analyze the results of a pressuremeter test in a pre-bored hole using cavity expansion theories but found that the results were highly sensitive to soil disturbance. To overcome the problem of soil disturbance, Menard developed standardized test techniques and directly correlated pressuremeter data to foundation design. Gibson and Anderson (1961) developed an analysis for the Menard pressuremeter which assumed that the undrained response of a saturated soil could be approximated by a linear elastic perfectly-plastic stress-strain relationship. For cylindrical cavity expansion, the undrained Young's modulus in the elastic region of the pressuremeter test can be obtained using : 46 AP AV Eu " 2 - Vo < 1 + *u ) 4.1 where 1 - initial volume of the probe AV — increment of volume AP — increment of pressure Eu,«/U - undrained Young's modulus and Poisson's coefficient Once the yield pressure Py - PQ + Su has been reached, the following expression holds : ' G AV AV • 1 + In- 1 _ S V ^ u Su- _ P = PQ + Su 1 + ln\ - 1 — Y . 4.2 where PQ = in situ horizontal stress G / Su - Ir - rigidity index V = VQ + AV — current volumetric strain In deriving equation 4.2, it is assumed that at the yield pressure, the vertical stress, az, is intermediate between the radial, ar, and circumferential ', Og, principal stresses. The limiting pressure at which infinite expansion of the cylindrical cavity occurs is given by : PL " Po + su I 1 + ln{ xr 1 1 Combining equations 4.2 and 4.3 results in : 4.3 P - PL + Su ln ' AV Vo PQ ' V G 4.4 In deriving equation 4.2, Gibson and Anderson also assumed that when the borehole for the pressuremeter is drilled, the soil stress is reduced from PQ to q£*z where q£ is the unit weight of the drilling fluid and z is the depth below the water table. Linear soil unloading is assumed to occur and subsequent increases in volume and pressure are 47 measured from this reference state. Windle and Wroth (1977) rederived eq. 4.4 assuming that the pressure and volume is measured from the in For a SBPM test in an approximately elastic perfectly-plastic soil, a plot of the pressure versus the natural logarithm of the current volumetric strain should yield a straight line relationship from which the average undrained shear strength can be determined. This is often referred to as the Windle and Wroth average strength method. Another major development in the analysis of the pressuremeter test in cohesive soils was by Palmer (1972), Ladanyi (1972) and Baguelin et al (1972) ( hereafter described as the Palmer,Ladanyi and Baguelin analysis) who independently derived a solution which allowed the undrained stress-strain relationship to be derived for a saturated soil for which no prior assumption concerning the stress-strain relationship needed to be made. Assuming that every element in the soil follows the same stress-strain curve, the shear stress at the cavity wall under plane strain conditions is given by : situ pressure PQ and corresponding volume Vo of the pressuremeter. The following expression is obtained : 4.5 ar - a9 eg (1 + eff)(2 + e9) dP r 4.6 2 2 8 48 For small strains this equation reduces to : dP T " €g 4.7 dig The stress-strain relationship of the soil can be directly derived from the pressuremeter test results using a graphical technique often referred to as the "subtangeht method" (Baguelin et al,1972). A more recent trend is to first empirically smooth or fit pressuremeter data using a mathematical function such as a polynomial expression (Fyffe et al, 1986) or hyperbolic expression (Arnold, 1981). Alternatively, mathematical expressions which assume a specific stress-strain relationship for a soil can also be fitted to pressuremeter data. Examples are Prevost and Hoeg's (1975) relationships for strain softening and hardening soils and Denby's (1978) relationship which assumes hyperbolic stress-strain soil behavior. The SBPM test, which in theory allows a pressuremeter membrane to be expanded in a soil at close to it's "at rest" conditions, is particularly well suited for analysis by cavity expansion theories. In contrast, the FDPM expansion curve is difficult to analyze using cavity expansion theory due to effects of cone pressuremeter penetration and the complex stress and strain fields which are created around the pressuremeter probe. The analysis of the unloading portion of the FDPM curve may be one solution to this problem. Houlsby and Withers (1987) present perhaps the first attempt at developing cavity contraction theory for an incompressible linearly elastic perfectly-plastic soil. Houlsby and Withers model the initial insertion of the cone pressuremeter as an expansion of a cylindrical cavity within the soil. 49 The expansion phase of the pressuremeter test is modelled as a continued expansion of the same cylindrical cavity. Expansion is allowed to continue until large strains and the limit pressure, P^, are reached. Unloading is assumed to occur from a known state of stress and to simplify the mathematics, the Hencky or logarithmic definition of strain is used for the cylindrical cavity contraction analysis. At the start of contraction the entire soil mass behaves elastically and the unloading curve follows a slope of 2G. Reverse plasticity initially begins at the cavity wall when the pressure is equal to (P^ - 2SU). As unloading continues, the plastic zone' moves outward from the cavity and plastic unloading occurs along the curve defined by the following equation : Su P - PL - 2SU [ 1 + ln( sinh( eL - e)> - ln{sinh( — )}] 4.8 G where e - ln( 1 + AR/RQ} - limit logarithmic strain Houlsby and Withers present two techniques to determine the undrained shear strength using the unloading analysis. The first method involves differentiating equation 4.8 with respect to e and multiplying both sides of equation the equation by (e^ " O which results in : UL - O dP de Su 4.9 where f - 4.10 tanh(£L - e) Since f is close to one for reasonable values of (e^ - e), an estimate of Su can be made using a graphical technique similar to the subtangent 50 method proposed by Baguelin et al (1972) for the analysis of the expansion curve. The second technique involves simplifying equation 4.8 by recognizing that for small values of (c^ - e), sinh(eTj - e) will be approximately equal to one. The following equation results : Su P - PL - 2S [ 1 + ln{eL .- e) - ln( — } ] 4.11 G From a plot of the pressure, P, against ( -lnfe^ - e}) a linear unloading curve with slope equal to 2SU should be obtained. Due to difficulty in analyzing the FDPM test theoretically, it is expected that empirical correlations will be used to a large extent when interpreting the FDPM test. One empirical use of FDPM data which has been validated by field tests is the derivation of the P-Y curve from the pressuremeter expansion curve for the purposes of predicting lateral load capacity of piles ( Brown, 1985, Robertson et al, 1983,1986). 4.2 Factors Affecting Pressuremeter Test Interpretation 4.2.1 Effects of Pressuremeter Insertion and Relaxation Period The insertion of any pressuremeter probe whether self-boring or full-displacement will create excess pore pressures. Ideally the insertion of a SBPM should cause a minimal amount of disturbance and only a small excess pore pressure will exist. Canou and Tumay (1986) suggest that a total pressure or excess pore pressure increase of greater than 50 % over the "at rest" conditions during the self-boring process is indicative of soil being forced away from the probe. The amount of relaxation time needed to allow pore pressures to come to 51 equilibrium will depend on a soil's permeability. Several hours relaxation time are often needed even for self-boring insertion performed carefully. The insertion of a cone pressuremeter when compared to SBPM insertion will result in a greater amount of disturbance and larger excess pore pressure. In Fig. 4.1 , Baguelin et al (1978) compare the pressure expansion curves obtained in soft clay from SBPM tests performed with no relaxation period and a long relaxation period and a FDPM test with no relaxation period. As expected, the FDPM lift- off pressure is the highest followed by the SBPM test with no relaxation period or time wait. Both cone pressuremeters used for this study did not have the capability to measure pore pressures at the pressuremeter membrane/soil interface thereby making a determination of the effective stress conditions at the beginning and during a test difficult. However, information from the piezo-lateral stress cone, the dilatometer and the piezoblade can all provide valuable insights into the total and effective stress conditions present after cone pressuremeter penetration. Azzouz and Morrison (1988) present data obtained by the Massachusetts Institute of Technology (MIT) piezo-lateral stress cone (PLS) from tests in lean sensitive Lower Boston Blue clay and plastic non-sensitive Lower Empire clay. Both clays are lightly overconsolidated. The pore pressures measured immediately after cone penetration had stopped were a large percentage of the total stress ( > 85% for Boston Blue clay ). Furthermore, the effective horizontal stress initially decreased as the pore pressures dissipated and only after 52 SOFT CRAN CLAY 150 CL 100 V Fig. 4.1 Effect of Pressuremeter Insertion Method and Relaxation Time on Pressure Expansion Curves ( after Baguelin et al, 1978 ) 53 approximately 50 % dissipation did the effective horizontal stress increase again to the stress measured immediately after PLS insertion. Although the geometry of the dilatometer and cone pressuremeter are different, it is reasonable to expect that the effects of probe insertion will be similar. Comparisons between the dilatometer lift-off pressure, PQ, and piezoblade pore pressure taken 15 seconds after penetration has stopped, suggest that the dilatometer PQ value is dominated by the penetration pore pressures for normally consolidated or lightly overconsolidated clays (Campanella and Robertson,1983, Lutenegger,1988 ; Fig. 4.2). For heavily overconsolidated soils, the pore pressures created by dilatometer insertion are a much smaller percentage of the dilatometer lift-off pressures as shown by Fig 4.3. The effect of varying lengths of relaxation time on lift-off pressures was assessed for data from Lulu Is.-UBCPRS using the UBC SCP. For the purposes of this research, the relaxation period has been defined to start when the cone tip passes the soil horizon where the pressuremeter test is performed. However, pore pressures may still be generated along the cone-soil interface. Quick tests were begun 15-30 seconds after cone pressuremeter penetration stopped resulting in approximately 1 1/4 to 1 3/4 minutes total relaxation time. This is due to the fact that the middle of the pressuremeter body is 1.34 m behind the cone tip and the cone pressuremeter is pushed at approximately 2 cm/s. The quick tests were compared to tests at about the same depth with relaxation periods of 7-13 minutes. The results, which are shown in table 4.1, indicate that the lift-off pressure decreases as the length of relaxation time increases. 54 DMT P0 (kPa) Fig. 4.2 : Comparison Between Dilatometer PQ and Penetration Pore Pressures from Piezoblade in Normally Con solidated and Lightly Overconsolidated Clays (after Luttenegger, 1988) DMT P0 (kPa) Fig. 4.3 : Comparison Between Dilatometer PQ and Penetration Pore Pressures from Piezoblade in Overconsolidated Clays (after Lutenegger, 1988) 55 Table 4.1: Effect of Relaxation Time on FDPM Lift-off Pressures. | Depth j Lift-off Pressure j Relaxation Time | j (m) j (kPa) j (min) | 4.8 1 H7 | < 1 3/4 | | 4.75 1 98 | 7.51 7.9 1 160 | < 1 3/4 | | 7.75 1 H2 | 9.7| 10.9 | 200 | < 1 3/4 | | 10.75 1 170 | 13| 14.0 1 304 | < 1 3/4 | | 13.75 1 »' 1 7.2 j Allowing pore pressures to dissipate after cone pressuremeter penetration has halted will also cause the soil surrounding the probe to consolidate. At Lulu Is.-UBCPRS the permeability of the soil is highly variable. As already indicated in Chapter 3, the time for 50 % dissipation ( t^Q ) of excess pore pressures ranged from 90 to 5000 seconds for the pore pressure sensor located at the base of the cone tip. For some of the FDPM tests with long relaxation periods, it is probable that a significant amount of consolidation occurred before the tests were begun. Figure 4.4 shows typical comparisons of quick tests and tests where pore pressure relaxation was allowed to occur. Although the tests were performed at slightly different strain rates, the steeper pressure expansion curves and higher limit pressures for the tests with longer relaxation periods suggest that consolidation can be of considerable importance when interpreting the results of FDPM tests. 56 LULU IS. UBCPRS PEAT 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 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 10 15 20 25 30 CAVITY STRAIN £ ( s ) LULU IS. UBCPRS ORGANIC CLAYEY SILT i t 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 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 10 15 20 25 30 CAVITY STRAIN £ ( s ) Fig. 4.4 : Effect of Relaxation Time on FDPM Tests at Lulu Is. - UBCPRS 57 In summary, it is reasonable to expect that the stress conditions immediately after cone pressuremeter insertion are dominated by penetration pore pressures. Furthermore, both the lift-off pressure and shape of the pressuremeter curve will be affected by the changing stress conditions which occur during the relaxation period and therefore standardized test methods should be used. 4.2.2 Effects of Strain Rate Most cavity expansion theories used to analyze pressuremeter test results in cohesive soils are based on the assumption that the soil remains undrained during a test. However, high gradients of excess pore pressure will cause partial consolidation to occur for a supposedly undrained test. For this reason, pressuremeter tests are run quickly, often several hundred times faster than laboratory tests. A detrimental effect of high strain rates is that the viscous nature of the soil becomes more important. In practise it is very difficult to separate consolidation and viscous effects. Wroth (1984) conceptually presents how the results of a SBPM test in an elastic perfectly-plastic soil that obeys a Mohr-Coulomb failure criterion could be affected by partial consolidation. Wroth suggests that partial consolidation will increase the effective stress state of the soil and increase the shear stress along the Mohr-Coulomb failure surface. This will result in an "undrained" shear strength which is progressively increasing as failure of the soil occurs. Eden and Law (1980) using data from a SBPM equipped with a pore pressure transducer mounted at the center of the pressuremeter membrane, present effective stress curves from pressuremeter tests which support Wroth's hypothesis. 58 Numerical analysis has also been used Co model the effects of partial consolidation and creep or viscous effects on pressuremeter test results (Anderson et al, 1987; Baguelin et al, 1986). Anderson et al (1982) used a finite element method analysis and modelled the soil using the modified Cam clay approach. Partial consolidation was included using a Biot type analysis with pore pressure coupled to the skeleton behavior through the principal of effective stress. The effects of deviatoric creep were also included in the analysis. Consolidation and creep were analyzed separately and together. Increasing the amount of consolidation during a pressuremeter test resulted in an increase in the limit pressure and the derived Su using the Palmer, Ladanyi and Baguelin analysis described in section 4.1 while increasing the amount of creep during a test reduced the limit pressure and Su. When analyzed together, the effects.of creep and consolidation tended to cancel each other out. Several field studies have been done to assess the affect of strain rate on Su obtained from SBPM tests (Windle and Wroth, 1977; Fahey and Carter,1986 and Benoit and Clough,1986). Windle and Wroth (1977) tested stiff Gault clay using a four fold difference in strain rate. No difference in Su was found using the Windle and Wroth average strength method. The peak Su derived from the Palmer, Ladanyi and Baguelin analysis showed an increase of approximately 25 % as the strain rate was increased. Fahey and Carter (1986) reported that a 2 1/2 fold increase in the strain rate did not change the Su obtained using the Windle and Wroth average strength method. Benoit and Clough (1986) found that for stress controlled SBPM tests, the Palmer, Ladanyi and Baguelin peak Su increased approximately 16 % when the stress increments were increased from 6.9 to 47.6 kPa/min 59 It is believed that strain rate effects will be similar for SBPM and FDPM tests. One advantage of using the cone pressuremeter is that consolidation characteristics of a soil can be estimated from the pore pressure dissipation data obtained from the piezocone. It is likely that the effects of partial consolidation will be significant for pressuremeter tests performed in the clayey silts at McDonald Farm and Lulu Is-. -UBCPRS since both piezocone pore pressure dissipation plots and oedometer tests give coefficients of consolidation which are relatively high for a cohesive soil ( see Chapter 3 ). 4.2.3 Effects of Disturbance The effect of soil disturbance and soil remoulding is of major importance when interpreting the results of pressuremeter tests. Baguelin et al (1978) theoretically analyzed the effect of a remoulded zone of soil around the pressuremeter by modifying the Palmer, Ladanyi and Baguelin analysis so that it used different stress-strain properties for the remoulded and unremoulded soil. The analysis indicated that although the initial slope of the pressure expansion curve will be reduced, the theoretical limit pressure should not be affected. For practical limits of cavity strain reached ( approx. 20 % ) , they also concluded that the practical limit pressure should not be affected when the self-boring insertion and pressuremeter test are performed with care. The insertion of a cone pressuremeter will create much more disturbance than the proper insertion of a self-boring probe and therefore, disturbance could possibly reduce the practical limit pressure reached. 60 Disturbance can also significantly affect the derived undrained shear strength from a SBPM test. Both Baguelin et al (1978) and Prevost (1979) theoretically showed that a remoulded zone around a pressuremeter probe will result in a stress-strain curve with a higher peak Su. Eden and Law (1980) and Benoit and Clough (1986) showed that a slightly oversized SBPM cutting shoe could cause soil stress relaxation and disturbance leading to an underprediction of the in situ horizontal stress and overprediction of Su. Benoit and Clough found that SBPM tests with an oversized cutting shoe analyzed using the Palmer, Ladanyi and Baguelin method led to undrained shear strengths which were 60 - 100 % higher than Su determined from tests using a normal sized cutting shoe. Wroth (1984) suggested that the Windle and Wroth method of determining the average undrained shear strength is a satisfactory method of determining Su and infers that the Palmer, Ladanyi and Baguelin analysis is more sensitive to the initial stress and strain datum chosen. The effect of disturbance on the determination of shear modulus will vary depending on how the shear modulus is calculated. Several different shear moduli can be obtained from SBPM test results : 1. ) An initial tangent or secant modulus can be calculated from the pressuremeter expansion curve. 2. ) A derived modulus can be calculated from the derived stress-strain curve. 3. ) An unload-reload loop during the loading stage can be used, Gur, or a reload-unload loop during the unloading stage, ^ru; Of these 3 techniques, the unload - reload modulus, Gur, is considered as the most reliable and least affected by disturbance ( Jamiolkowski et 61 al, 1985). The insertion of a FDPM probe will create considerably more disturbance that the insertion of a SBPM. Nevertheless, Hughes and Robertson (1985) present Gur values from SBPM and FDPM tests in sand which are in good agreement suggesting that at least for sands, Gur is insensitive to the method of pressuremeter insertion. 4.2.4 Effects of Pressuremeter L/D Ratio The analysis of pressuremeter test results using cylindrical cavity expansion theory will be somewhat in error due to the finite length of the pressuremeter. The problem will be magnified for expansions taken to large strains. For an incompressible elastic perfectly-plastic soil the limit pressure for spherical cavity expansion will be : PL - Po + 4/3 Su ( 1 + In Ir ) 4.12a which will be somewhat larger than the limit pressure for cylindrical cavity expansion : PL ' Po + Su < 1 + ln Tr > 4-12b Baguelin et al (1986) analyzed the influence of L/D ratio for an elastic perfectly-plastic soil by simulating SBPM tests using finite element analysis. The derived shear modulus, G, and undrained shear strength, Su, for various L/D ratios are compared to G^, and Suoo obtained for the ideal plane strain case. The results are given below : 62 Table 4.2 : Numerical Simulation of SBPM Tests with Varying L/D Ratio for Elastic Perfectly-Plastic Soil ( after Baguelin et al, 1986). L/D G/Gw | 1.23 Su/Su» I 1-22 The results of the numerical analysis indicate that for a SBPM with L/D of 6, using cylindrical cavity expansion theory will lead to only a slight overprediction of G and Su> The influence of finite L/D ratio on FDPM test results is affected by the insertion of the cone pressuremeter. If the insertion is modelled using cylindrical cavity expansion theory, the radius of the plastic zone for an elastic perfectly-plastic soil is given by Randolph and Wroth (1979) : Rp - r0 ( Ir >'5 4-13 where rQ = radius of the pressuremeter Ir - rigidity index A typical FDPM expansion of approximately 25 % cavity strain would increase the radius of the elastic-plastic boundary to at least 1.25 r (Ir)*^. In contrast, a typical expansion of 15 % cavity strain for a SBPM test would result in a plastic zone radius of .57r (I_),~'. r ox r' Table 4.3 compares the radius of the plastic zone with the length of the pressuremeter probe for the FDPM and SBPM probes used for this research. Maximum expansions of 15 and 25 % cavity strain are assumed for the SBPM 63 and FDPM probes respectively and the soil rigidity index is assumed to be equal to 200. Table 4.3 : Effect of Insertion Method on the Radius of the Plastic Zone for an Elastic Perfectly-Plastic Soil. PM I I I I I I I | PM | PM | PM | Cavity | Max. Radius | R^ | | j Radius j L/D | Length j Strain j of Plastic j — j I I r I I \ I I Plastic Zone | L | | | ( mm ) | |(mm)|(%)|P^(mm)| | UBC SCP | 22 | 5 | 120 | 25 | 389 | 3.24 | FUGRO CP j 22 I 10 j 220 j 25 j 389 j 1.77 | HUGHES SBPM I 37 I 6 I 222 I 15 I 298 I 1.34 I The high RpAp ratio for the UBC SCP suggests that cylindrical cavity expansion is not an accurate representation of the actual expansion occurring and therefore spherical cavity expansion may be a more appropriate analysis to use. 4.3 Comparison of SBPM and FDPM Tests FDPM and SBPM expansion-contraction curves are compared at similar depths for Lulu Is.-UBCPRS and McDonald Farm in Figs. 4.5 and 4.6. Similar strain rates were used in all cases and unless otherwise noted the tests were begun after a short relaxation period of approximately 1 to 5 minutes duration. Several general observations can be made about the test results. 1.) The shapes of the FDPM and SBPM expansion curves at both sites are similar for cavity strains greater than approxi mately 5 %. 64 MCDONALD FARM CLAYEY SILT 600 H "i i i i i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—r SCP 17.0 m UBC SCP 16.75 m HUGHES SBPM € «= 8.5 */min L/D«=5 t - -1 */min L/D-6 a J 1 1 1 i I i i i i |—i—i—i—i—|—i—i—i—i—|—i—i—i—r 0 5 10 15 20 25 CAVITY STRAIN £ ( % ) MCDONALD FARM CLAYEY SILT 900 19.0 m UBC SCP i =9.1 */min L/D=5 18.75 m HUGHES SBPM i =-1 «/min L/D=6 19.2 m FUGRO CP t = 5 */min L/D=10 1 1 ' I I I I I I I I I I I I | I I I I I I I I I 0 0 20 30 CAVITY STRAIN £ ( g ) Fig. 4.5a,b : Comparison of FDPM and SBPM Tests at McDonald Farm 65 MCDONALD FARM CLAYEY SILT 1000 T—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—j—i—i—i—r a SBPM 22.0 m UBC SCP £ - 8.1 «/min L/D=5 21.75 m HUGHES SBPM i «= 10 «/min L/D=6 5.0 */min L/D=10 22.2 m FUGRO CP £ = 5.0 0 1 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 0 20 30 CAVITY STRAIN £ ( s ) MCDONALD FARM CUVYEY SILT 1000 o CL 3 00 00 LU or CL i i i i i i i i i i i i i T~ i ~r i I i i ri i •~r ~ b . • - - it**-«*" j a i —/ ' •f s ^— • --25.0 m UBC SCP £ • 7.0 */min 24.75 m HUGHES SBPM e =-10 */min L/D=5 L/D=6 i i i i I i 1 1 1 | 1 1 I 1 | 1 I i i I 1 1 1 1 5 10 5 20 CAVITY STRAIN £ ( % ) 25 Fig. 4.5a,b : Comparison of FDPM and SBPM Tests at McDonald Farm 66 LULU IS. UBCPRS PEAT 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—r a 4.8 m HUGHES SBPM I a 4.3 «/min 4.8 m UBC SCP t = 10.8 %/mm ' 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 10 15 20 25 30 CAVITY STRAIN 6 ( % ) LULU IS. UBCPRS ORGANIC CLAYEY SILT ' 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 b -" i i i i | i i i i | i i i i | i i i i | i i i i | i i i i ( 5 10 15 20 25 30 CAVITY STRAIN 6 ( * ) Fig. 4.6a,b : Comparison of FDPM and SBPM Tests at Lulu Is.-UBCPRS 67 LULU IS. UBCPRS ORGANIC CLAYEY SILT 300 o Q_ £ 150-j CO cn LU on a. 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 a j 7.9 m UBC SCP fc - 10.6»/min 7.9 m HUGHES SBPM fc - 8.5 */min SCP 0 | I I 1 I | I I I I | I I I I | I I I I | I I I I | I I I 1 0 5 10. 15 20 25 30 CAVITY STRAIN £ ( * ) LULU IS. UBCPRS ORGANIC CLAYEY SILT 300 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 9.4 m UBC SCP £ = 12.4*/min 9.4 m HUGHES SBPM £ = 12.1*/min SCP 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 10 15 20 25 30 CAVITY STRAIN 6 ( * ) Fig. 4.6a,b : Comparison of FDPM and SBPM Tests at Lulu Is.-UBCPRS 68 2. ) At low strains the pressuremeter expansion curves are steeper for the SBPM tests. 3. ) At Lulu Is.-UBCPRS, the SBPM expansion pressures are generally slightly lower than those obtained for the FDPM probe. 4. ) At McDonald Farm, the SBPM expansion pressures are higher than those obtained for the FDPM probe. At low strains the pressuremeter expansion curves are significantly steeper for the SBPM tests. 5. ) Most of the FDPM expansion curves have a slight bump for cavity strains between 0 and 4 %. The probable cause of this effect is a combination of pressuremeter strain arm design , in-accurate zero readings for the strain arms and difficulty in accurately determining the membrane correction at low strains. This problem is covered in more detail in Chapter 2. 6. ) As expected, lower practical limit pressures are obtained for the FUGRO CP with a pressuremeter L/D of 10 as compared to the UBC SCP with a L/D of 5. An interesting result is that the expansion pressures obtained for the SBPM probe at McDonald Farm are higher than the FDPM pressures but lower for tests performed at Lulu Is.-UBCPRS. A factor which may have led to this result is that the self-boring procedure at Lulu Is.-UBCPRS probably produced a greater degree of disturbance than the self-boring at McDonald Farm due to the difficulty encountered in self-boring through the fibrous peat and organic clayey silt at Lulu Is.-UBCPRS. Furthermore, the organic silt at Lulu Is.-UBCPRS is a moderately sensitive clayey silt which would be affected by disturbance to a greater degree than the slightly sensitive clayey silt at McDonald Farm. FDPM, SBPM and dilatometer lift-off pressures are compared for all three test sites in Fig. 4.7. The pressuremeter lift-off pressures for all tests were obtained by visually determining the lift-off for each strain arm and then taking the average. Unless otherwise noted, the 15-MCDONALD FARM LIFT OFF PRESSURE ( kPa ) 200 400 600 800 1000 i i ,| I i i i I i i i I i i i I • i LULU IS. UBCPRS LIFT OFF PRESSURE ( kPa ) DILATOMETER PO 20 H 25H UJ Q 30 H 35-* FUGRO CP • UBC SCP ~ 1.5 MIN RELAXATION a HUGHES SBPM •'''I' i i i i i i i 20-100 200 300 ' I i I ' ' ' I i • i ' • 1 400 DILATOMETER PO * UBC SCP -1.5 MIN RELAXATION + UBC SCP~7-13 MIN RELAXATION a HUGHES SBPM ' I ' iiii! 5H 10H Q. LU a LANGLEY LOWER 232 LIFT OFF PRESSURE ( kPa ) 150 300 450 600 ' ' I l I I i i I I i • • • l DILATOMETER PO 15-1 v>u. + UBC SCP ~ 7-30 MIN RELAXATION on- I I I I i l I I i i i t I I I I i i • M , Fig. 4.7 : Comparison of FDPM, SBPM and Dilatometer Lift-off Pressures 70 pressuremeter tests were performed after short relaxation periods of approximately 1 to 5 minutes duration. The SBPM lift-off pressures are in general slightly lower than the FDPM lift-off pressures and at McDonald Farm, the SBPM lift-off pressures are significantly more variable than the FDPM results. The variability of the SBPM lift-off pressures and the fact that for numerous tests the SBPM and FDPM results are almost the same suggests that the insertion of the SBPM may have created a substantial amount of disturbance. The dilatometer and FDPM lift-off pressures are difficult to compare due to the differences in probe geometry and the way lift-off pressures are measured. For all sites, the dilatometer lift-off pressures are higher than the FDPM values. This may be due in part to shorter relaxation period for the dilatometer test and smaller amounts of stress relaxation occurring during dilatometer penetration due to the less abrupt change in geometry between the tip and blade of the dilatometer. The practical limit pressure, P^, is defined as the pressure at 20 % cavity strain for the FDPM probes and 15 % for the SBPM probe at Lulu Is.-UBCPRS and 10 % at McDonald Farm. For pressuremeter tests in which the maximum cavity strain obtained was slightly less than 10,15 or 20 %, the pressuremeter expansion curves were extrapolated to the required strain by eye. The practical limit pressure obtained using the FDPM and SBPM and the dilatometer P^ value are compared for all three sites in Fig. 4.8. A good comparison between the FDPM and dilatometer is obtained. MCDONALD FARM PRACTICAL LIMIT PRESSURE ( kPa ) 0 300 600 15-20-25-30 35 J I I 1 1 1 L 900 1200 _J I i_ DILATOMETER P1 • P20 FUGRO CP • P20 UBC SCP aP10 HUGHES SBPM i i « I I I 1 1 1 1 L 5-10-15-20-LULU ISLAND - UBCPRS PRACTICAL LIMIT PRESSURE ( kPa ) 125 250 375 500 ' i i i I i i i ' I i i i i l i i i i —DILATOMETER PI -• P20 UBC SCP *- 1.3 MIN RELAXATION • P20 UBC SCP ~ 7-13 MIN RELAXATION OP15 HUGHES SBPM i i i i i i i i i i i i i i i i I i i LANGLEY LOWER 232 PRACTICAL LIMIT PRESSURE ( kPa ) 0 200 400 600 0-1—I—I—X—I—I I I I I i i I i 5-10-a. Ld a 15-20-DILATOMETER PI + P20 UBC SCP 7-30 MIN RELAXATION -I—I—I—I I 1 I • t i t J i Fig. 4.8 : Comparison of FDPM and SBPM Practical Limit Pressures and Dilatometer Values 72 4.4 Parameters Obtained from the Pressuremeter Test The results of FDPM and SBPM tests are used to determine four geotechnical parameters: undrained shear strength, shear modulus, in situ horizontal stress and stress history. The main focus of this section of the thesis is to explain the methods employed and the assumptions made in determining these parameters. To a lesser extent, a review has been made of comparisons between parameters obtained using the pressuremeter and other in situ and lab tests. 4.4.1 Undrained Shear Strength There are two approaches which can be used to obtain the undrained shear strength from pressuremeter tests ; a theoretical approach based on cavity expansion or contraction theory or an empirical approach. Both approaches are considered in this thesis. The undrained shear strength is theoretically obtained using the following methods : the Windle and Wroth average strength method for the analysis of SBPM and FDPM expansion curves, the Palmer, Ladanyi and Baguelin method using pressuremeter data empirically fit using a hyperbolic equation as suggested by Arnold (1981) for the analysis of SBPM expansion curves and the Houlsby and Withers (1987) unloading method for the analysis of FDPM contraction curves. Since the stress conditions are unknown at the beginning of a FDPM test, strictly cavity expansion methods should not be used for FDPM tests. Nevertheless, there are indications which suggest that a reasonable estimation of Su can be made despite the disturbance created by FDPM insertion. In section 4.2 , comparisons of SBPM and FDPM tests performed at the same depth indicate that the expansion curves are similar for cavity strains greater than 5 73 %. Also encouraging are good comparisons between Su determined from SBPM and PIP tests using the Windle and Wroth average strength method (Fyffe et al, 1982). The Windle and Wroth average strength technique is shown in Fig. 4.9 for typical SBPM and FDPM test results. The current volumetric strain is related to the cavity strain by the following equation : AV 1 1 4.13 VQ + AV (1 + eg)2 The Arnold (1981) type 1 analysis uses a hyperbolic relationship ; €8 P - Q + 4.14 a + beg to empirically fit the pressuremeter curve. The value Q represents the offset on the pressure axis and ideally represents the in situ horizontal stress while the parameters a and b are obtained by a numerical procedure using three points from the experimental expansion curve. The stress-strain curve is derived assuming small strains (equation 4.7). The following equation results : aeg T _ 4 15 ( a + be& )2 A point which is often overlooked is that for even relatively small strains equation 4.15 will significantly underpredict the shear stress. For example, at 10 % cavity strain the shear stress is underpredicted by approximately 16 %. For this reason the Arnold type 1 analysis has been slightly modified to allow the stress-strain curve to be derived using 74 HUGHES SBPM Site : Lulu Is. UBCPRS Depth : 6.35 m Dote : 11/2/87 0.1 1 10 100 LOG CURRENT VOLUMETRIC STRAIN x UBC SCP Site : Lulu Is. UBCPRS Depth : 6.35 m Dote : 3/4/87 0.1 1 10 100 LOG CURRENT VOLUMETRIC STRAIN % Fig. 4.9 : Determination of Undrained Shear Strength using the Windle and Wroth Average Strength Method 75 the more accurate equation 4.6. The resulting equation for the shear stress is : ae ( 1 + e )(2 + e) T 4.16 2 ( a + be )2 A SBPM expansion curve fitted using a hyperbolic relationship and the resulting stress-strain curve is shown in Fig. 4.10. The process of fitting a hyperbolic curve to the expansion pressure-cavity strain data is naturally a subjective process which becomes more difficult as the pressuremeter data deviates from the hyperbolic form. The last theoretical technique used is the Houlsby and Withers unloading analysis. Figure 4.11 illustrates how a linear curve with slope equal to 2SU for cylindrical unloading is obtained when the pressure is plotted against ( -ln{eL - e) ), where eL is the limit strain. Figure 4.11 also shows how the rigidity index can be obtained. Two empirical methods are used to determine Su from FDPM and SBPM tests. The first method involves using a relationship often used in the analysis of Menard pressuremeter data : 4.17 where P^ — limit pressure as defined as the pressure at AV / (VQ + AV) - 1 Amar et al (1975) reported that a N factor equal to 5.5 results in a Su which compares well to field vane and triaxial test Su for soft ( Su < 50 kPa ) cohesive soils. For this research the practical limit pressure as defined in section 4.2 is used in equation 4.17. The N factor is found using the field vane as the reference S . HUGHES SBPM 11/2/87 Lulu Is. UBCPRS Depth = 6.35 m 200 | 190 -~l 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 2 4 6 B 10 12 U 16 18 Covfty Strain (X) —— Data Points + Arnold Curve Fit Fig. 4.10 : Determination of the Stress-strain Curve using the Modified Arnold Type 1 Analysis 77 UBC SCP 27/1/87 McDONALD FARM Houlsby Cylindrical Unloading D = 22 m 0 2 4 6 8 10 -ln(Eu- E) E=Natural Strain Fig. 4.11 : Determination of Undrained Shear Strength using the Houlsby Unloading Analysis 78 The second empirical method uses the following expression for Su : 4.18 The practical limit pressure is again used for P^. Although this method is virtually identical to the common relationship for the piezocone which uses qt in place of P^ in equation 4.18, it is felt that using the FDPM test data may help confirm the Su obtained just using the cone bearing. The validity of this method is supported by the consistent relationship between qt and P2Q for normally consolidated soils as shown in Fig. 4.12. Ratios ranging from approximately 1.3 to 2.0 were found for the three testing sites. In general, pressuremeter undrained shear strength obtained using cavity expansion methods are significantly higher than Su obtained using other in situ or laboratory tests. Table 4.4 is a comprehensive review of experimental test results comparing the self-boring pressuremeter to the field vane and triaxial test. One result for a prebored pressuremeter is also included. For most test comparisons, the pressuremeter Su is between 1 and 2 times higher than the triaxial or field vane. Although not shown in Table 4.4, the results from the Gothenburg site tested by Wroth and Hughes (1974) and the San Francisco Bay - Site 1 tested by Clough and Denby (1980) indicate that as the clay approaches the normally consolidated condition at depth, the pressuremeter strength increasingly becomes higher than the vane or triaxial strength. This effect may be due to soil anisotropy. As discussed in section 4.2, consolidation effects, a remoulded soil annulus around the pressuremeter and cavity expansion which is not 1 MCDONALD FARM J L Qt / P» 1 J I I l_ J I l_ ••••• q, Avg. 8 CPT Teat*. P„ UBC SCP »»> q, Avg. 8 CPT Teat*. P„ Fugro CP —I 1 1 1 I I ' • 1 5H 0. UJ a 1SH 20-LULU IS. - UBCPRS qt / P» J I I L 2 J L .Pa :UBC SCP 1.5 MIN RELAXATION +++*+* .Pa) :UBC SCP 7-13 MIN RELAXATION. J l_ J I L J l_ 0.0 10-CL UJ O 15H 20-J I LANGLEY LOWER 232 qt / P» 1.0 2.0 1 1 1 I I u + H + + Sand Layer + q, ,P» .-UBC SCP 7-30 MIN RELAXATION J J I 1 I i i J L Fig. 4.12 : Comparison of Cone Bearing and FDPM Practical Limit Pressure Table 4.4: Comparison of Undrained Shear Strength fron Pressuremeter, Field Vane and Triaxial Teata Slca Soil Type Type of PH Used Type of PK Teat Plasticity Index Msthod of Interpreta tion Number of PH Tests Su PH Su FV Su PH Su TC (UU) Su PH Su TC (CK0U) Reference Gothenburg Soft Clay Caabrldge Stress Controlled Palmer 6 1.3-2.5 Ulndle & Wroth SBPH 3.45 kPa/30 sec (1974) Cran Soft Clay PAFSOR - 80 • - 1.2 2.0 Anar et al (1975) Cran Hed. Plastic - 30 - 1.5 1.8 Slit Plancoet Hed. Silt - 20 • - .75 1.5 Provlna Soft Clay - 10 • - 1.25 1.67 Provlna Alluvial Silt • - - • - 1.25 1.67 with Peat Bosse Calln Stiff Clay * - 80 - .78 Soft Clay * - 80 • - 1.8 2.25 Lanestar Plastic Clay m - - • .94 Begles Organic m - - - 1.43 • Plastic Saint Andre Peat m Strain * • 5 1.04 Baguelin et al de Cubzac Controlled (1972) Soft Clay 35 27 1.45 * Canvey Is. Soft Sllty Cambridge Stress 45 5 1.22 Hughes et al (1975) Clay SBPH Controlled Hadlngly Stiff Cault » 44 U&U 18 1.0 Ulndle & Wroth Clay 13 1.3 (1977) Hendon Stiff Sticky • 40 Clay Palmer NRC Site Soft Senal- • 36 3 1.3 Eden & Law (1980) ( Leda ) tlve Clay 9.S kPa/aln 1.72 Hatagaml Plastic Clay • • 34 4 • 9.8 kPe/mln South Soft Sensi 29 • 5 1.8 • Gloucester tive Clay 9.1 kPa/aln San Fran Soft Clay • 45 Osnby 10 1.14 Clough & cisco Sltel 3.AS kPa/30 aec Denby (1980) San Fran- Soft Clay m 30-35 • 15 1.43 1.11 • claco alte2 3.45 kPa/30 aac Onsoy Soft Clay • 2B+-8 tf&U 12 1.99 1.72 Lacaase et al 9.1 kPa/aln (1981) Draoraen Plastic Clay • 30 6 1.92 1.63 • • Porto Tolle Sllty Clay - 30+-2 a 14 1.15 1.07 Chlonna et al(1981) Panlgaglla Sllty Clay * - 47+-3 " 12 3-1.2 3.2-1.4 • Taranto Stiff Hard - 27+-3 m 7 1.25 • Clay Burswood la Soft Clay Stress Controlled - 12 1.85 Fahey & Carter 20 &. SO kPa/aln (1986) Bangkok Harlne Clay 0Y0 LLT - 60 46 1.20 Bergado & Prebored Khaleque (1986) PH - Pressureaeter Palmer - Derived Su Using Palmer, Ladanyi and Baguelin (1972) Hethod TC - Triaxial Compression W&U - Ulndle and Uroth (1977) Average Su Hethod UU - Unconsolidated Undrained Denby - Denby (1978) Su Hethod Ck0U - K Consolidated Undrained G&A - Gibson and Anderson (1961) S Hethod 81 truly cylindrical will all lead to an overprediction of Su and may be some of the reasons for the differences observed in table 4.4. Furthermore, when comparing pressuremeter and triaxial tests, a much higher strain rate is generally used for pressuremeter tests and this may lead to higher estimates of Su. The measured Su will also be affected by the in situ or laboratory method used and the stress path followed during a test. Wroth (1984) states that the definition of Su as half the difference between the major and minor principal stress does not allow for the influence of the intermediate principal stress and does not distinguish between different types of tests which can result in different strengths for identical soil samples. In an attempt to overcome this problem, Wroth linked the results of different tests by relating Su / <7vo' to the phi angle. For a normally consolidated soil he suggested a possible profile of strength would be as indicated in Fig. 4.13. Ladd et al (1979) suggested that the pressuremeter Su should lie between the results of direct simple shear and plane strain compression tests. 4.4.2 Shear Modulus The shear modulus obtained from an unload-reload loop, Gur, performed during the expansion phase of a pressuremeter test appears to be the least affected by disturbance when compared to other definitions of shear moduli ( Jamiolkowski et al, 1985). Assuming soil response is linear elastic, cylindrical cavity expansion theory can be used to obtain the following equation for G . 82 a) Ukaly variation in undralnad b) Ukaly Marareny 0, ur#3rain«cJ atrangth ratio for diffarant ttrangtn ratio for dtffarant tast Mtnooa taat aatnotis TEST TYPES PH - Prassura matar K0TC- K0 consolidatad triaxial comprassfon - Plaid Van* OSS - Otraet stmpla snaar 4.13 Hierarchy and Variation in Undrained Strength Ratio for Various Test Methods ( adapted from Wroth, 1984) 83 AP ( 1 + e ) Gur - 4.19 2 Ae where em — cavity strain at the mid point of the unload-reload loop A derivation of equation 4.19 is found in appendix IV. When performing an unload-reload loop, care must be taken not to exceed the "elastic" limit of the soil. For an elastic perfectly-plastic soil the maximum theoretical amount of unloading which can occur before the initiation of failure at the cavity wall is AP = 2SU ( Wroth ,1982). In reality soil behavior is non linear even for the small strain increments used for unload-reload loops. Jamiolkowski et al (1985) presented SBPM test results for the Porto Tolle and Panigaglia soft clay sites which indicate that Gur tends to increase as the strain increment at the cavity wall decreases. Several researchers have attempted to show how the shear modulus attenuates with increasing shear strain for cohesive soils. Two results are shown in Fig. 4.14 in which the shear modulus has been normalized by the dynamic small strain modulus. The Seed and Idriss (1970) average relationship is based on both cyclic and monotonic tests while the Kokusho et al (1982) relationship is based on cyclic triaxial tests. It is not clear why there should be such a large difference between the two curves. Based on the data shown here, the relationship between shear modulus and shear strain appears to be approximate and not well defined. During a pressuremeter unload-reload loop, the strain increment is measured at the cavity wall. To allow a better comparison of Gur with the data shown in Fig. 4.14, the average strain increment in the soil 84 SHEAR MODULUS ATTENUATION CURVES 0.0001 0.001 0.01 0.1 1 10 SHEAR STRAIN y ( * ) Fig. 4.14 : Shear Modulus Attenuation Curves in Cohesive Soils 85 should be determined. The author is unaware of any published work which has addressed this difficult problem for cohesive soils. The use of Gur is further complicated by the fact that the modulus depends, inter alia, on the mean normal effective stress state of the soil at the beginning of and during a test if drainage occurs. For a SBPM test in which drainage is minimal, the effective stress during a test will likely be close to the in situ effective stress state. In contrast, the insertion of a cone pressuremeter will create high excess pore pressures and a low effective stress state at the cavity wall. Some drainage will inevitably occur due the high pore pressure gradients surrounding the pressuremeter and therefore the average effective stress will be difficult to determine during a FDPM test. For the purposes of this research it has been assumed that for both FDPM and SBPM tests, the mean effective stress stays approximately constant during a test and is equal to the in situ effective stress. All unload-reload loops were performed quickly with a full loop taking place in under 5 seconds. Most unload-reload loops were performed with no delay between expansion and the loop. A few tests were performed after a standing period of between 2 and 17 minutes. For the Fugro CP and Hughes SBPM the pressure remained constant during the creep phase while the cavity strain increased. The opposite effect took place during the creep phase involving the UBC SCP probe. The second method of determining the shear modulus involves utilizing the rigidity index obtained using the Houlsby and Withers unloading analysis for FDPM tests ( Fig. 4.11 ). The shear modulus is calculated using the undrained shear strength obtained for cylindrical unloading : 86 Gu - Ir Su 4.20 A drawback of this method is that it is difficult to accurately associate a strain increment with the modulus obtained. In general, shear moduli computed from SBPM tests are higher than those obtained from laboratory tests. In only a few cases has Gur been compared to the results of laboratory tests for cohesive soils. Windle and Wroth (1977) and Kay and Parry (1982) compared SBPM Gur to Gur obtained from an unload-reload loop during UU triaxial tests for London and Gault clay and found that the SBPM Gur were 2.5 to 3.0 times higher than those obtained during triaxial tests. The results presented by Windle and Wroth (1977) also indicated that the SBPM Gur is approximately equal to Gur measured during a plate loading test. Jamiolkowski (1985) compared Gur from SBPM tests in soft clays at Porto Tolle and Panigaglia to G^Q from" CKoU direct simple shear (DSS) tests and found that the SBPM modulus was approximately 1.5 to 3 times higher than the DSS modulus, the magnitude of the ratio being affected by the size of the unload-reload volumetric strain increment used. Several factors which likely contribute to the large differences in moduli are the effects of clay anisotropy, the difference in strain rate or stress paths between SBPM and laboratory tests and the effects of disturbance on moduli calculated from laboratory tests. 4.4.3 Stress History The piezocone has been used to a limited extent to estimate the stress history or overconsolidation ratio ( OCR - a-p'/avo' ' ap' = preconsolidation pressure ) of a cohesive soil. Much of the research to date has focused on correlating the B parameter : 87 Au Bq 4.21 *t " avo to the overconsolidation ratio ( Wroth, 1984; Jamiolkowski et al, 1985; and Robertson et al, 1985). Sully et al (1988) proposed a new method to predict OCR using the normalized difference in pore pressure measured at the tip, u^, and directly behind the tip, U2> as defined by : ul * u2 PPD - : 4.22 uo The new method, called the pore pressure difference or PPD method, appears to be quite promising for overconsolidation ratios less than 15. The author is unaware of any published research in which the results of pressuremeter tests are directly correlated to the stress history of a cohesive soil. Two correlation methods are proposed which use the data obtained from a cone pressuremeter and seismic piezocone soundings. The first method relates the practical limit pressure with OCR using the following expression : OCR - f > PL " *vo "vo 4.23 This method is similar to the correlation with OCR suggested by Wroth (1988) which uses the piezocone qt in place of P^ in equation 4.23. From information reported by Lacasse et al (1981), Wroth calculated values of (qt - avo^/avo' ^or depths of 2 to 20 m at Onsoy and plotted them against relevant values of OCR from oedometer tests ( Fig. 4.15 ). 88 Fig. 4.15 : Variation in (qt - Svo)/SVQ' with OCR at Onsoy ( after Wroth, 1988 ) 89 The rational for using equation 4.23 is identical to the one given by Wroth (1988) except that is used in place of qt since P^ appears to be proportional to qt. By modifying equation 4.23 so that : PL " CTvo PL _ avo Su Su - Np 4.24 avo' Su Svo' CTvo' a better appreciation is given why equation 4.23 should be related to OCR. The undrained shear strength ratio SU/CTvo' varies with OCR in a well defined way. The relationship between OCR and Np is similar to the relationship between OCR and N^t as will be shown in chapter five. The second proposed method correlates the rigidity index, Ir, against OCR. From a comprehensive review of laboratory data by Wroth et al (1984a), it appears that I generally decreases with increasing OCR. For some tests Ir initially increases slightly and then decreases with increasing OCR. Figure 4.16 gives the relationship between Ir and OCR from CKQU DSS tests performed on three clays. The definition of Ir used in this research uses the average dynamic shear modulus, Gmax, obtained from dowhhole seismic testing and the field vane Su. Seismic testing was performed during some of the UBC SCP test penetrations and during some of the seismic piezocone penetrations adjacent to the cone pressuremeter test holes. The field vane Su was used since it was felt that the field vane profiles were more comprehensive and reliable than the pressuremeter Su profiles. The SBPM test has become a well accepted technique of determining the in situ horizontal total stress of a soft cohesive soil, afa0, provided that the installation is performed carefully and sufficient relaxation time is allowed for stresses around the pressuremeter to Fig. 4.16 : Values of G/Su Plotted Against OCR from CKDU DSS Tests on Three Clays ( after Ladd and Edgers, 1972 ) 91 reach an equilibrium. Experience in stiff clays is more limited ( Jamiolkowski et al, 1985 ). Several techniques have been proposed for evaluating ano from SBPM and Menard pressuremeter tests. A comprehensive review of these methods are given by Lacasse and Lunne (1983) and Denby and Hughes (1982). Lacasse and Lunne (1983) suggested that the techniques available for determining anQ could be divided into three classes of interpretation methods : approaches related to the direct measurement of the "initial" or "lift-off" pressure; empirical approaches; and approaches which use the complete pressuremeter curve to determine the initial pressure. Of these three classes, only the empirical approach is valid for the tests performed with the UBC SCP and Fugro CP probes because of the short relaxation times used and the large amount of disturbance created during the insertion of these probes. The same rational holds for the Hughes SBPM although it is likely that the disturbance created will be less severe. The empirical approach is based on the limit pressure obtained for the infinite expansion of a cavity in an elastic-perfectly plastic soil ( Gibson and Anderson, 1961). The in situ horizontal stress for cylindrical cavity expansion is : aho ' PL ' V 1 + ln{Ir> > 4-25 while the equation for spherical cavity expansion is : aho " PL - 4/3 V 1 + ln(Ir) > 4-26 The results of FDPM tests are analyzed using both equations 4.25 and 4.26 since it is felt that because of the effects of the full displacement insertion, spherical cavity expansion may more closely 92 model the actual expansion process. A drawback associated with the empirical approach is that erno is sensitive to the values of the undrained shear strength and the rigidity index. For this approach, the in situ horizontal stress is calculated using Su and Ir obtained from the Houlsby and Withers unloading analysis and the limit pressure used is the expansion pressure at 20 % cavity strain. 93 CHAPTER 5  UNDRAINED SHEAR STRENGTH 5.1 Reference Undrained Shear Strength The field vane undrained shear strength has been chosen as the reference strength for this research. The field vane test is currently the most common in situ method for measuring the undrained shear strength and has been proven to be a reliable and highly repeatable test method. There are also several disadvantages with the test. Penetration through coarse grained or stiff cohesive soils can damage the vane blades and therefore preboring is usually required through these types of soils. Furthermore, the verticality of the vane penetration can not be controlled or measured. The Nilcon and Geonor field vanes used have vane height to diameter ratio of 2 as recommended by the standard according to ASTM ( ASTM D2573). The undrained shear strength is calculated using the standard expression : Su - 6T/7*D3 5.1 where T - applied torque D - diameter of the vane Several factors such as soil anisotropy, strain rate effects, disturbance due to vane insertion and the length of time delay between vane penetration and shearing all affect the measured Su. A comprehensive discussion of the importance of these factors is given by Grieg (1985). 94 Researchers such as Bjerrum (1973) and Aas et al (1986) have proposed correction factors for field vane Su based on a review of excavation and embankment failures for which field vane strengths were available. They found that the theoretical factor of safety differed from 1 and could be correlated to the plasticity index of the clay. No correction factors have been applied to the field vane data for this research since the undrained shear strength obtained from pressuremeter tests is not corrected. The undrained shear strength from the field vane and the normalized undrained shear strength profiles for the three test sites are shown in Fig. 5.1 and 5.2 respectively. The SU/CTvo' values at McDonald Farm and at Langley Lower 232 below 16 m are constant and indicate an approximately normally consolidated soil deposit. The small amount of scatter in Su at Langley Lower 232 indicates a relatively homogeneous deposit. The Su and Su/cvo' profiles at Lulu Is. - UBCPRS are more difficult to interpret. In Chapter 3 it was suggested that the soil profile between 2.5 and 5.0 m consists of highly organic silt or. peat. This would account for the high Su's measured at these depths. Both Kaderabek at al (1986) and Landva (1986) state that the field vane test in peat is difficult to interpret and the Su obtained is often erratic and higher than the Su obtained from other in situ tests. The high field vane undrained shear strength at 13 m depth may have been caused by a thin silty sand layer. To help make a more accurate assessment of the reference undrained shear strength at Lulu Is.-UBCPRS, the cone bearing data from five CPTU tests is utilized as shown in Fig. 5.3. A cone factor of Nkt equal to 10 15-MCDONALD FARM Su Field Vane ( kPa ) 25 50 75 i i i i » i i i i .1 i i t i l i i t 100 79 a. UJ a 23 +++++ Fvr-1 ••••• FVT-2 70 1 1 1 ' ' ' 1 1 1 1 ' ' 1 ' ' ' ' 1 ' ' E . w10-15H 20-LULU ISLAND - UBCPRS Su Field Vane ( kPa ) 20 40 60 80 •1 I I I I I I I I I I I . • • • +++++ rvT-i • H 0.0 5H E a 15-20 H 25-LANGLEY LOWER 232 Su Field Vane ( kPa ) 20.0 40.0 60.0 -I—I—I I I i i I I I I -R«f. S.-/ • * ••••a FVT— 1 t>i>>>> p/f—2 • o >B> ooooo FVT-3 L ° +++++ FVT-4 • o • ••••• FVT-5 a o -I—l—I—I—l—I—I I ' • • • • Fig. 5.1 : Field Vane Undrained Shear Strength 0.0 MCDONALD FARM Su Ft / Ovo' 0.2 15-0.4 i i i i i- i i I t i i i i i i I i 0.0 + 20 H + H 25 H (S. / <W)» - 0.33 +++•+ FVT-1 •••••FVT-2 30-Woter Table - 1.0 m + • + + ' ' ' ' ' ' i i i i i i i 5H 10H 13H 20-LULU ISLAND - UBCPRS 1.0 2.0 J 1 1 1 I I i i • (S. / cj)m S 0.4 J •••••FVT-1 Water Table - 1.5 m J 1 1 l i • LANGLEY LOWER 232 s.w / o\.' 0.0 0.5 1.0 1.5 I I ' I I I I I I I I I I I I I 3H 10H O 15H 20 H 25-2.0 •> • a • O-B OO o o > o O a o •> o •> o o o o aaaao FVT—1 p/T—2 oooooFVT-3 +•+++ FVT-4 ••••• FVT-5 (S. / °J)m - 0.26 J Water Table - 1.0 m i i i i i i i t i t t i i i i • i Fig. 5.2 : Normalized Field Vane Undrained Shear Strength 97 LULU ISLAND - UBCPRS Su ( kPa ) 20 40 60 80 J I L J I L J I L J I L 10-Q_ UJ O 15-+++++ FIELD VANE PROPOSED REFERENCE Su AVG. S„ FROM 5 CPT TESTS USING Su = (qt - o\o)/NKt ; N„t = 10 20 J l I I I I I i i i i '''' Fig. 5. 3 : Proposed Reference Su For Lulu Is. UBCPRS 98 is used to calculate Su since this produced a good match between the field vane and CPTU data for depths greater than 5 meters. Using the combined data from the field vane and CPTU, a reference undrained shear strength for Lulu Is.-UBCPRS is proposed. 5.2 Theoretical Methods Three theoretical techniques of obtaining the undrained shear strength outlined in Chapter 4 were utilized for this study. The Windle and Wroth (1977) average strength and Houlsby and Withers (1987) (Houlsby for short) unloading analysis were applied to both FDPM and SBPM test results while the Palmer, Ladanyi and Baguelin analysis using pressuremeter data empirically fit using a hyperbolic equation as suggested by Arnold (1981) was used for SBPM test data. All plots showing the calculation of Su using these techniques are included in appendices I to III. 5.2.1 Windle and Wroth Average Strength Method The undrained shear strength determined from the Windle and Wroth average strength technique is shown in Fig. 5.4. Unless otherwise indicated, all tests were performed with short relaxation periods equal to 1 to 5 minutes duration. At McDonald Farm the pressuremeter Su is approximately 1.25 to 2.25 times higher than the reference Su. The superscript s is used to distinguish tests run at approximately 5 to 10 % strain per minute from tests where the strain rate is less than or equal to 2 %/min. It appears that the slower tests result in a higher Su possibly due to consolidation occurring during the test. The SBPM and FDPM undrained MCDONALD FARM S„ ( kPa ) 15- i i 50 I I I I 100 150 '•till 20-25-30-R«f. S. rv aooaaUBC SCP »*>»>»•»> FUGRO CP +•+•+Hugh6» SBPM SUPERSCRIPT S INDICATES TEST PERFORMED SLOWLY WITH A STRAIN RATE < 2 %/nin 35- • » • • • J I IIII LULU ISLAND - UBCPRS S„ ( kPa ) 0 25 50 75 100 p. |-1 i i i I i i i i I I 1 i i I I I I I 5-10-15-20-Re'* ^*/anm aooaaUBC SCP 1.5 min RELAXATION ••••• UBC SCP 7-13 min RELAXATION ••+++HughM SBPM i i i i i i i i i i i i ^ 5-10-I us o 15-LANGLEY LOWER 232 S,, ( kPa ) 20 40 60 1 1 1 1 1 1 1 I 1 1 1 I 1 • • \ • ; R«f. S»iv-A • : SCP~7-30 min RELAXATION -i i i i i • i i i i i i i Fig. 5.4 : FDPM and SBPM Undrained Shear Strength from Windle and Wroth Average Strength Method 100 shear strengths are similar and appear to increase at the same rate as the reference undrained shear strength. Furthermore, the scatter for the pressuremeter test results is similar to that obtained for the field vane. At Lulu Is.-UBCPRS, the FDPM tests performed with short relaxation periods and the majority of the SBPM tests result in undrained shear strengths which are close to the reference Su. The low SBPM undrained shear strengths calculated at depths equal to 9.4, 10.9 and 12.4 m were possibly caused by a relatively greater amount of soil disturbance created by the insertion of the SBPM. As already noted in Chapter 3, the organic nature of the soil deposit at Lulu Is.-UBCPRS makes the jetting technique of SBPM insertion difficult to accomplish without clogging of the self-boring cutting shoe. It appears that allowing a longer period of relaxation between penetration and actual testing results in higher undrained shear strengths for the FDPM test. Furthermore, for several tests additional problems in interpretation were created by the period of creep allowed before an unload-reload loop was performed. Ideally, no unload-reload loops should be performed for tests in which obtaining the undrained shear strength is the primary objective. The measured undrained shear strengths at Langley Lower 232 are approximately twice as high as the reference undrained shear strength. The difference between the pressuremeter and reference Su would likely have been less if shorter relaxation periods had been used for the FDPM tests. 101 5.2.2 Arnold Curve Fitting Method The SBPM undrained shear strength calculated using the Arnold curve fitting technique modified to allow for a more accurate derivation of Su ( as discussed in section 4.4.1 ) is shown in Fig. 5.5. Comparative values of the modified and unmodified Arnold undrained shear strength can be found in appendices I and II. On average, the unmodified undrained shear strengths are approximately 5 % lower than the modified values. The Su obtained using the Windle and Wroth average strength technique is included to allow a comparison of the two methods. At McDonald Farm and Lulu Is.-UBCPRS the modified Arnold method results in undrained shear strengths which are generally slightly higher than the Windle and Wroth method. This trend is reversed for a few tests at shallow depths at Lulu Is.-UBCPRS. In general a good agreement was obtained between the two methods. At McDonald Farm, the curve fitting of the pressure-cavity strain data was made more difficult by the small number of data points acquired due to the limitations of the data acquisition system used. Nevertheless, it is felt that the subjective process of the curve fitting leads to range of undrained shear strengths which is no greater than 5 % of the given Su for most tests. 5.2.3 Houlsby Unloading Method The undrained shear strength calculated using the Houlsby cylindrical analysis of the FDPM unloading curve is shown in Fig. 5.6. At McDonald Farm and Lulu Is.-UBCPRS, the Houlsby undrained shear strength is 55 to 75 % of the reference Su while at Langley Lower 232 the percent ratio ranges from 65 to 110 %. Furthermore, the Houlsby Su for McDonald Farm and Lulu Is.-UBCPRS increases with depth at a similar MCDONALD FARM Su ( kPa ) 0 50 100 150 1S | i i i i I i i i i I i i i i I. 20-25 30-35 +++++Windle and Wroth Avg. S, ••••• Arnold Curve Fit S» (modified) SUPERSCRIPT S KJtCATES TEST PERFORMED SUmY WITH A STRAIN RATE < 2 u/rrin i « I l l I I I 5-10-15-20-LULU ISLAND - UBCPRS S„ ( kPa ) 25 50 75 100 i i-i i I i i i i I i i i i I i i i i Ref. Safv/tow -+•••• windle and Wroth Avg. S. ••••• Arnold Curve Fit S, (modified) l l • ' ' ' ' • ' i i ' ' Fig. 5.5 : SBPM Undrained Shear Strength from Arnold Curve Fitting Method 15-McDONALD FARM S„ ( kPo ) 25 50 75 100 I I I I I > I I I » I I I I I I t L I 20-I 25-30-• Ref. S, »y . 35-aaaaaUSC SCP e>**M> FUGRO CP i ' « lit LULU ISLAND - UBCPRS S« ( kPa ) 0 20 40 60 i i i I i i i I i i i i i i 5-10-15-o o if a R«f. S, ft/tarn 80 LANGLEY LOWER 232 Su ( kPa ) oooooUBCSCP 1.5 min RELAXATION •••••UBC SCP 7-13 mln RELAXATION I i i i i i i i i i i i 5-10-15-20-20 40 60 J I I I I I I I I I I I • / : • / Ref. S,w • • \ -1 1 1 i.llll .1. .1., i i I.. Fig. 5.6 : FDPM Undrained Shear Strength from Houlsby Unloading Method i 104 rate to the reference Su. In contrast, the Houlsby Su profile at Langley Lower 232 does not have a similar shape to the reference Su. For the tests near the ground surface at Langley Lower 232, the dis-similar shape may have in part been caused by the difficulty in estimating the Su due the non-linear nature of the unloading curve using the method outlined in Chapter 4 ( also see appendix III ). The generally low undrained shear strength from the Houlsby unloading analysis can perhaps be attributed to the stress paths followed during the test. During unloading, the radial total stress rapidly decreases and quickly becomes less than the tangential total stress. This is somewhat analogous to the stress conditions during a triaxial extension test and may explain why the Houlsby unloading undrained shear strengths are low. The results from all three sites showed less scatter than the reference Su from the field vane test. This trend may have been caused by a partial loss in soil heterogenity during the loading portion of the test. Also interesting to note is that it appears that the amount of relaxation time before a test is performed does not significantly affect the undrained shear strength measured. 5.3 Empirical Methods The pressuremeter factors obtained using the first empirical method described in section 4.4.1 are shown in Fig. 5.7. The following equation was used to calculate N : Su - < PL - Po > / N 4-!7 PL - practical limit pressure Su •= reference Su 0.0 MCDONALD FARM N 2.0 4.0 6.0 8.1 I I I I I I ' • • I i • • »3 ooooo UBC SCP p-fft-f FUGRO CP ++•++ Hughes SBPM N - (P»-PJ N - (P»-PJ N - (V,»-PJ/ SUPERSCRIPT S INDICATES TEST PERFORMED SLOWLY WITH A STRAIN RATE ^ 2 a/mln J I J U J I I I I l_ 0.0 0 I ' 1 5-10-o. LU Q 15-20-LULU IS. UBCPRS N 2.0 4.0 6.0 J I I I I I I I u a a *> • a + + a + a + o + a a + « aaaaa UBC SCP N - (P»-P.)/S. „/wm 1.5 min REUOGATION UBC SCP. N - (P»-P.)/S.r//w« 7-13 min RELAXATION +++•+Hughes SBPM N =• (PiB-Pj/S. „w J I I I L _L 0.0 0-L-L 5-10-15-LANGLEY LOWER 232 N 2.5 5.0 7.5 i I i i i i I i i i i I i i i i 10.0 ••••• UBC SCP N - (P»-P.)/S, „ 7-30 min RELAXATKJN 2Q 1 1 1 1 1 1 IIIIIIII Fig. 5.7 : FDPM and SBPM Pressuremeter Factor N - (PL - PQ)/SU REF vs Depth 106 Assuming that the pressuremeter limit pressure and the reference Su can be related using the above equation, i.e., N is independent of other soil characteristics such as OCR, the ideal correlation would result in a N factor exhibiting a minimal amount of scatter and remaining constant with depth. At McDonald Farm the correlation obtained using the UBC SCP is quite good with a N value ranging between 2.5 and 3.0. The range for the Fugro CP is 2.2 to 3.5. The SBPM N values show considerably more scatter then the FDPM N values at McDonald Farm. At Lulu Is.-UBCPRS, the less homogeneous soil deposit results in a N profile with a lot of scatter and a range from 2.25 to 5.25. The result of varying amounts of relaxation time is also quite noticeable for the tests with the UBC SCP. A poor correlation is also obtained at Langley Lower 232 where N ranges from 4.5 to 8.5. The poor correlation over the first several meters at Langley Lower 232 is perhaps due to the fissured and partially saturated nature of the overconsolidated soil inhibiting the generation of large pore pressures and hence P2Q values. The results of the second empirical technique are shown in Fig. 5.8. The quality of the correlation between the pressuremeter and the reference undrained shear strength is perhaps slightly poorer than the first empirical method presented. The most consistent correlation is for the FDPM tests at McDonald Farm where Np range from 3.4 to 4 for the Fugro CP and 4.2 to 5.1 for the UBC SCP. At Lulu Is.-UBCPRS the range is between 3.7 and 6. Again a poor correlation is obtained at Langley Lower 232 where Np ranges from 5 to 11.5. The results of the second empirical method at Lulu Is.-UBCPRS appear to indicate that this method is less affected by the amount of 15-McDONALD FARM NP 0.0 2.0 4.0 6.0 8, I I I I I I I L_l I I I I 1 20-25-UJ a 30-8s + +• DOODOUBC SCP »»»»» FUGRO +++++ Hughei SBPM fl, - (PV£)/SL w 35-SUPERSCRfT S INDICATES TEST PERFORMED SUDWLY WITH A STRAIN RATE 4- 2 */ndn I I I I I I I I I I I I I 5-10-0. Ul Q 15-20-LULU IS. UBCPRS 2 4 6 I I I I I I I I I i_ 4- a oaaaa UBC SCP 1.5 min RCI N.-(PJD-< lELAXATION -O/s. . E n/oam ••••• UBC SCP N,=(P»-0/S. FVAXXC 7-13 min RELAXATION +++++Hugh«9 SBPM N,=(Pi8-o«)/S, nr/tac I I I I I I I I I I I I I l 0.0 3-10-15-20-LANGLEY LOWER 232 3.0 6.0 9.0 6.0 J I L. 12.0 UBC SCP N, - (Pa-oJ/S, n 7-30 min RELAXATION J I I l_ J I l_ o Fig. 5.8 : FDPM and SBPM Pressuremeter Factor Np - (PL - avo)/Su vs Depth REF 108 relaxation time allowed when compared to the first empirical method. For both methods, standardizing the amount of relaxation time before a test is performed would make the interpretation of the tests less difficult. An advantage of the cone pressuremeter is that the cone bearing and excess pore pressure measured during cone pressuremeter penetration can also be used to estimate the undrained shear strength. The traditional empirical expression for the undrained shear strength of cohesive soils uses a bearing capacity type equation of the form : 1c-SuNk+*vo 5-2 where qc - cone bearing - cone factor With the advent of the piezocone, the cone bearing is usually corrected for unequal end area effects. The corrected cone bearing and corresponding cone factor are designated as qt and N^-p. respectively. The cone factor will depend on the type of test used to obtained the reference undrained shear strength and the characteristics of the cohesive soil tested. A wide range of values are reported in the literature. From a review of the available literature, Greig (1985) suggests that there appears to be a general trend of decreasing cone factor with increasing plasticity index. For a given plasticity index, it also appears that increases with increasing sensitivity. A more recent proposed method of correlation involves using the excess pore pressure in the following equation ( Robertson et al,1985): NAu=Au/Su 5-3 where Au «- u - uQ 109 The N^u measured will depend on the location of the pore pressure element on the cone and the stiffness, sensitivity and stress history of the soil being tested. The values of and N^u calculated for this study are shown in figure 5.9 and 5.10. The N^u correlation uses the excess pore pressure, U2, measured just behind the cone tip. The best and N^u correlations are obtained at McDonald Farm. The cone factors are approximately constant with depth and are within a narrow range. At Langley Lower 232 the and N^u values show a moderate amount of scatter but vary considerably with depth in approximately the same manner as the pressuremeter factors N and Np do. At Lulu Is.-UBCPRS, the values vary over a large range. In contrast, the N^u values are much more closely spaced with the exception of the N^u obtained from the UBC SCP probe at several depths. The difference in quality between the two correlations can probably be partially attributed to the fact that in the soft organic clayey silt the pore pressure transducer is operating at 20 to 30 % full output while the load cell measuring cone bearing is operating at less than 1 % full output and therefore is less reliable. The undrained shear strength empirically calculated using the FDPM factor N and the cone factor are compared to the reference undrained shear strength in Fig. 5.11. The FDPM N values are the calculated average values from the profiles in Fig. 5.7. The results at McDonald Farm indicate an excellent correlation between the FDPM, cone and reference Su. At Lulu Is.-UBCPRS, a constant N^t equal to 10 produces a cone Su profile with a wide range. The correlation between the limited number of FDPM Su's and the reference Su appears to be slightly better. 15-20-25-McDONALD FARM NM J I L 10 IIII 30-ooooo CPTU—1 OOODO CPTU—2 -*>»»-»-»> CPTU-3 ooooo CPTU-4 ft**** CPTU-5 44444 CPTU-6 KKKKM CPTU—7 ••••• CPTU-B <x»a*+ • ot>D •> OOD 4 «Oft>«- X o»a • 0*>D*» •>*•• + o Ma + o >a+ •> o ota + o NO+ o »• o ft* o »•» + o •*» + 15 ( Qt - or» ) -i r* 35- • ' i I I I I I I I I—I—I—L 5-i a 10-15-20-LULU IS. UBCPRS N« 5 10 15 20 25 I I I I I I I I I I 1 I I I I LI I I I I I I I > a •+ • a o» > <m 4 • >a o • + t>a o 4 • Oft- o • 4 a « *• a fto+ • a o i> • • •• «o+ a *• 4 o o • 4 oooaa CPTU—1 fr>>t>t» CPTU—2 ooooo CPTU-3 44444 CPTU-4 UBC SCP-2 ' • ' ' ' • ' ' • • ' ' ' ' ' • ' i ' i i i i i 5-E a. Id a is-20-25-I I LANGLEY LOWER 232 Nkt 5 10 15 ' i I ' ' ' ' I i ' i ' l • 20 I I aaaaa CPTU-1 »>»>»>B>e> CPTU-2 ooooo CPTU-3 ••••• CPTU-4 44444 UBC SCP • • +0-O a «+ o > > o> 40 >B> • 4 O +0 • OH> + I I IIII «•> t> + «a o*. • <11> 4 • a> ©• 4 • o-oa •> a + B>4H-4 mo 4 o n of av • Oft-a«4 4 -'''''' Fig. 5.9 : Cone Factor Nkt - (qt - *vo)/Su REF vs Depth 1 15-20 H 25H 30 H MCDONALD FARM ( Ni„ >2 5 10 J I I I I i i I i 1 t t i • o» <•<><*• ••a ot> • « Ofr • •W O* • -K> <X> •+o <» •fa e * o » o * o » o •+ o +o « > •B «• HO l> 15 ooooo CPTU—1 OOOOD CPTU—2 SE™-? (N*)« - flu, / s,w •CPTU-4 ••••• CPTU-6 ••••• CPTU-8 35- J i_ -I I L -I I I I I L I O 15-20-LULU ISLAND - UBCPRS 5 (N*j)2 i—i—i l i i u LANGLEY LOWER 232 10 J 1 I I I L 15 *> • » o « >•>• AU, tan- • M + o • • OOOD CPTU—1 »»»»» CPTU-2 ooooo CPTU-3 +++++ CPTU-4 •••••UBC SCP-2 J I I I I I I I I I I I I L 0 5 Q I I I I I I I 5-H 10H u 15H 20 H 25-(N«u)l 10 I I I 15 20 .1 I I I I i.i QWs -a o >• DO -a o -• t» oa -• t> o o -• i> oo -• t> oa -I> o • -• > «l -AU, -Sg PV o t» a -o a -o t> a -aaaaa CPTU-1 e»*e>t»t> CPTU-2 • CPTU-3 UBC SCP i i ' i »i wo •O I I I I I I I Fig. 5.10 : Cone Factor NAu - Au/Su REF vs Depth 1 MCDONALD FARM S„ ( kPa ) 25 15 20-i a 25-30-35-50 75 100 i i »' I i i i i I i i i i I i i t i I Ref. S» n/ -RANGE OF S. FROM 8 CPT TESTS USING Ni •* 7.9 DDOQO t>t>t>»-t> UBC SCP SB-(P1»-P0/N : N-2.80T FUGRO CP S.=»(P,o-Pl;/N ; N»2.89. i i ' i i i i t i i i i i i i i i i i i 3-10-LU a 13-20-LULU IS. UBCPRS S„ ( kPa ) 20 40 60 _J I I I I i i i I LANGLEY LOWER 232 80 RANGE OF S, FROM 3 CPTU TESTS USING S» - (p,-a J/H, : NM - ID Ref. S« n/oom •DODO UBC SCP 5, - (P.-PJ/N ;N=>2.85 1.5 min RELAXATION UBC SCP S» - (P«,-P-)/N :N-4.5 7-13 min RELAXATION i- i.. i i i i i i i i i i i 0 0 I ' • 5-& a 10-15-20-S„ ( kPa ) 20 40 ' ' • • ' 60 I I I I -Ref. S. n RANGE OF S. FROM 5 CPTU TESTS USING S, - (q, - aJ/N*, ; Ntt a 13 ••••• UBC SCP S. - (P.-PJ/N ;N=6.44-7-30 min RELAXATION J—I I—I l I I I i i t i t Fig. 5.11 : Comparison of Su using FDPM Factor N and Cone Factor N| I 113 At Langley Lower 232, a fair correlation is obtained between the FDPM, cone and reference Su but unfortunately the pressuremeter and cone Su profile does not follow the same trend as the reference Su. 5.4 Conclusions In general, the undrained shear strength obtained using the Windle and Wroth average strength method ranged from being approximately equal to the field vane Su at Lulu Is.-UBCPRS to 1.25 to 2.25 times higher at McDonald Farm and Langley Lower 232. A good comparison was obtained between FDPM and SBPM tests using the Windle and Wroth average strength analysis. The pressuremeter undrained shear strength for McDonald Farm, when compared to the reference Su, follows the same trend with depth and has a similar amount of scatter. At Lulu Is.- UBCPRS the scatter in the data is likely due to soil variability. When tests were performed using variable strain rates, the slow tests resulted in higher undrained shear strengths which were likely caused by consolidation during the tests. Furthermore, when relaxation times prior to a test were increased, the undrained shear strength also increased significantly. In summary, the Windle and Wroth average strength method appears to be a reasonably valid method when used for the analysis of FDPM despite the fact that theoretically cavity expansion methods should not be used when the initial stress conditions are not known. The Houlsby unloading analysis resulted in Su values which were generally less than the reference Su. When compared to the results of the Windle and Wroth average strength method, the results showed less scatter which may be due to a loss of soil heterogenity during the loading portion of the pressuremeter test. 1 14 An excellent correlation was obtained between the traditional empirical method of calculating the undrained shear strength and reference Su for McDonald Farm with N factors ranging between approximately 2.2 and 3.0 for tests were conducted using similar strain rates. At Lulu Is. - UBCPRS and Langley Lower 232 the N factors were more variable. The poor correlation near the ground surface at Langley Lower 232 was likely a result of the overconsolidated and fissured nature of the soil crust. When compared to the cone parameters and N^u, the pressuremeter parameters N and Np appear to exhibit the same dependence on soil characteristics. In summary, the empirical methods presented are a useful means of estimating Su provided that standard test procedures are followed and correlations are limited to localized areas. 1 15 CHAPTER 6  SHEAR MODULUS AND RIGIDITY INDEX 6.1 Shear Modulus The unload-reload shear modulus, Gur, and the shear modulus, GJJ, calculated using the rigidity index and undrained shear strength from the Houlsby cylindrical unloading analysis is presented in Fig. 6.1. The shear modulus is not adjusted for varying stress or strain levels. Plots showing the calculation of the shear modulus can be found in appendices I to III while a summary of the shear modulus values are in appendix V. The results at McDonald Farm indicate that the shear modulus is approximately constant with depth and that the Gur and G^ values are similar. The high unload-reload shear moduli obtained at 16.2 m depth with the Fugro CP can be attributed to the small strain increments used for the unloading loops. At 27.5m the high Gur and GJJ values calculated for the UBC SCP are most likely caused by the consolidation of the soil around the pressuremeter probe during a 17 min creep phase before the unload-reload loop was performed. Since no pore pressure measurements were made during a pressuremeter test , no attempt was made to correct for changes in the effective stress state of the soil surrounding the probe. For several other unload-reload tests short periods of creep ranging from 2 to 5 minutes were allowed to occur before the unload-reload loop was performed. The short periods of creep appear not to significantly affect the shear modulus obtained. The shear moduli at Lulu Is. -UBCPRS vary over a wide range and indicate a softer soil than the soil tested at McDonald Farm. The MCDONALD FARM SHEAR MODULUS ( MPa ) 0 10 20 30 40 15 I i ' ' i I i ' ' i J i i i i I i » i 20-25-CL UJ a 30-35-D t>tr a > aaaaa UBC SCP GH Houlsby Unloading >t,t>» UBC SCP C +++++ FUGRO CP GH Houlsby Unloading ••••• FUGRO CP C _l_ I I I I I I I I I I I I I I 5-fc Q 10-15-20-LULU IS. UBCPRS SHEAR MODULUS ( MPa ) 2 4 6 a * oa a * # 0 * oo * a * * * > °o * * 0 * » o° * * -DDOOD UBC SCP GH Houlsby Unloading " UBC SCP Gl ***** Hughes SBPM G» ..l.J 1 1 1 1 1 1 1 1 1 1 1 LANGLEY LOWER 232 SHEAR MODULUS ( MPa ) 0 1 2 3 4 5 1 i 1 I 1 1 1 l i 1 i I 1 1 1 I 1 1 1 5-fc a 10-15-20-DOOOO UBC SCP GH Houlsby Unloading 1 1 1 1 1 1 1 1 1 1 1 1 1 Fig. 6.1 : Unload-Reload, Gur, and Houlsby Unloading, GH, Shear Modulus vs Depth 1 17 Houlsby unloading shear moduli appears to be on average slightly higher than the unload-reload modulus. At Langley Lower 232 the GJJ values indicate a soil which appears to have approximately the same stiffness as the Lulu Is.-UBCPRS soil deposit. Unfortunately, unload-reload shear moduli are not available for this site. Although the equation for the unload-reload shear modulus ( eq. 4.19 ) Is derived using a linear elastic soil model, in reality soil behavior is non-linear even for the small strain increments used for the unload-reload loops. Therefore a better understanding of the shear modulus can be obtained by normalizing GUR with respect to the dynamic small strain modulus, Gmax and plotting the ratio against the cavity shear strain increment. This has already been done for shear moduli from cyclic and monotonic lab tests in Fig. 4.14. An approximate average GMAX profile at each site used for the normalization of GUR is found in Fig. 6.2. At McDonald Farm and Lulu Is.-UBCPRS below 5 meters, Gmax appears to increase linearly with depth while at Langley Lower 232, a non linear increase of GFFLAX is observed with depth. Also interesting to note are the extremely low GMAX values in the organic clayey silt or peat at Lulu Is.-UBCPRS between 3 and 5 meters depth. The normalized unload-reload shear modulus plotted against the shear strain increment for McDonald Farm and Lulu Is.-UBCPRS is shown in Figs. 6.3 and 6.4. The Houlsby unloading shear moduli are not analyzed in this manner due to difficulty in accurately determining a strain level for the shear modulus. It should be emphasized that the shear strain increment from an unload-reload loop is the strain increment at the cavity wall and not the average strain increment in the soil. MCDONALD FARM Gmax ( MPa ) 50 100 i b i i I L_ Avg. Gmax J l L 150 Gmax - pV. V. - Shear Wave , Velocity J ••••• SCPT--1 Acc] ••••+ SCPT-•2 Geo ooooo SCPT--3 Ace] SCPT-•4 Ace, oaooo SCPT--5 Geo ooooo SCPT-•6 'Geo, -I I L -I L -I I L 5-^ 10H 15H 20-LULU IS. UBCPRS Gmax ( MPa ) 20 40 J 1 1 i i i i Gmax - pV, V, - Shear Wove Velocity Avg. Gmax ••••• SCPT-1 (Acc) +++++UBC SCP-2 (Acc oooooUBC SCP-2 (Acc UBC SCP-2 (Acc aoooa UBC SCP-2 (Acc' _l_ LANGLEY LOWER 232 Gmax ( MPa ) 0 20 40 Q I I I t I I I I I I I I I I I I I I 3H i a 10H 1SH 20-Gmax - pV.* V, - Shear Wave Velocity Avg. Gmax ••••• SCPT-1 (Geo) +•+•• UBC SCP-1 (Acc) UBC SCP-1 (Acc) I i i i i i i i i i i i i i i i i • i Fig. 6.2 : Dynamic Small Strain Shear Modulus, G . vs Deoth ' max' r 119 MCDONALD FARM o.o -j 1 1—i i i i i 11 1—i—i I I I I 11 1—I—I I I I I 11 0.01 0.1 0 SHEAR STRAIN y = 2e„ ( % ) Fig. 6.3 : G /G vs Shear Strain at McDonald Farm 120 LULU IS. UBCPRS 0-00 -j 1 1—i i i i i 11 1 1—i I I i i 11 1—i—i i i i i 11 0.01 0.1  - 0 SHEAR STRAIN y = 2zv ( % ) Fig. 6.4 : G /G vs Shear Strain at Lulu Is.-UBCPRS 121 Therefore, a direct comparison between the pressuremeter unload-reload results and the Seed and Idriss and Kokusho shear modulus attenuation curves reproduced from Fig. 4.14 can not be made. Nevertheless, a qualitative comparison can be made realizing that the average strain increment will likely be a constant ratio of the strain increment at the cavity wall. At McDonald Farm, the normalized Gur/Gmax values are between .08 and .65 with most points falling between .08 and .24. The normalized Gur attenuates with increasing shear strain in a manner similar to the behavior for Teganuma soft clay. At Lulu Is.-UBCPRS, the GI1T./G values are between .07 and .22. A good comparison is obtained \JL JL Hid A. between Gur/Gmax from the FDPM and SBPM tests and the normalized Gur again attenuates in a similar manner to Teganuma soft clay. 6.2 Rigidity Index The rigidity index, Ir, was calculated in three different ways, the first two methods shown in Fig. 6.5. The first method uses parameters derived from the Houlsby unloading analysis while the second method uses the ratio of the Gur and the field vane undrained shear strength. The rigidity index is not adjusted for varying strain levels. Furthermore, the reference Su from the field vane is used with the unload-reload shear modulus since it is felt that the reference Su is more consistent and reliable than Su obtained using the pressuremeter. At McDonald Farm Ir for most tests ranges between 80 and 220. The rigidity index is approximately constant below a depth of 20 m. For most tests the Houlsby unloading Ir is slightly higher than Ir calculated using G MCDONALD FARM RIGIDITY INDEX ( lr ) 200 400 600 i i i I I I i I I I—I—L + • • • + ooooo UBC SCP lr Houlsby Unloading ••••^ UBC SCP \r=G„/Su mr ry +++++ FUGRO CP lr Houlsby Unloading • ••••FUGRO CP lr=G„/Su mr ry _l_ J I I I I I I I I L LULU IS. UBCPRS RIGIDITY INDEX ( lr ) 0 50 100 150 200 5H I a 15H 20-J u -I I i L * o o * » u «> o J »a' ooooo UBC SCP lr Houlsby Unloading UBC SCP Ir-Ggr/S, mr rv/eac »»»>»» Hughes SBPM I^Ctj/S pv/eaw _l_ 5H & a 10-15H LANGLEY LOWER 232 RIGIDITY INDEX ( lr ) 50 100 1 150 _L_ 200 ooooo UBC SCP L Houlsby Unloading J 20 J ' >- J I I L Fig. 6.5 : Gur/Su REp and Houlsby Unloading If vs Depth 1 23 At Lulu Is.-UBCPRS the rigidity index varies over a wide range. The rigidity index calculated using Gur for the SBPM and FDPM are similar and vary between 20 and 135 while the Houlsby unloading Ir ranges between 65 and 210. At Langley Lower 232 the Houlsby rigidity index ranges from 85 to 140. Although above 7 m depth the profile is not consistent, below 7 m Ir increases consistently with depth. Figure 6.6 shows the third method of obtaining the rigidity index using the average Gmax and the reference Su. At McDonald Farm the rigidity index is approximately constant with depth which is to be expected for a normally consolidated soil. At Lulu Is.-UBCPRS the results are somewhat unexpected since below approximately 6 to 7 m, the soil deposit is believed to be close to normally consolidated and above this only lightly overconsolidated. Furthermore, since the plasticity index and sensitivity are believed to be fairly constant with depth one would expect less of a change in Ir with depth. The low rigidity indices obtained near the surface are largely due to the extremely low shear velocities and therefore Gmax obtained in the organic clayey silt or peat. Even below 5 m the organic nature of the deposit may have had a slight effect on Gmax> The rigidity index could also be slightly in error due to incorrect soil densities assumed in the calculation of the G values. max At Langley Lower 232 the rigidity index is quite low at shallow depths and increase to a maximum at 8 m depth and then slightly decreases at lower depths. The change in rigidity index is to be expected since the degree of overconsolidation is decreasing with depth. It is also interesting to note that the rigidity index profile from the MCDONALD FARM RIGIDITY INDEX ( I, ) 0 250 500 750 1000 15 I i i i i I i i i i I i i i i I i i i i I | 20 25 H Q. UJ Q 30 H 35-Avg. Gmax lr = Ref. Su FV/OONE ' ' i ' ' ' ' i ' • ' i i i i 0 O-i-L. i a 10H 13H 20-LULU IS. UBCPRS RIGIDITY INDEX ( lr ) 200 400 600 800 ' I i i i I » i i ' ' • i ' • - • I, = Avg. Gmax Ref. Su FV/OONE •' 1 ' 1 1  LANGLEY LOWER 232 RIGIDITY INDEX ( lf ) 0 250 500 750 1000 0 I i i i I i i i i I i i i i I i • • • | , 5H icH Q. UJ a 15H Ir = Avg. Gmax Ref. S„ rv/coNE ?Q.I I I I I I I I I I t l i l i i i i i i M Fig. 6-6 : Gmax/Su REp vs Depth 125 Houlsby unloading analysis in Fig. 6.5 is unlike the profile obtained using Gmax and the reference Su. The difference in the two profiles near the ground surface may in part result from the difficulty in estimating the linear portion of the Houlsby unloading curve ( see section 5.2.3 ). Consequently, the Houlsby Su may have been underpredicted leading to an overprediction of the rigidity index. The rigidity index defined as Gur/Su gj-p is plotted against the shear strain increment for McDonald Farm and Lulu Is.-UBCPRS in Figs. 6.7 and 6.8. The Seed and Idriss relationship is included to provide a qualitative comparison between the results of pressuremeter and laboratory tests. At both McDonald Farm and Lulu Is. -UBCPRS the rigidity index attenuates with increasing shear strain in a manner similar to the Seed and Idriss relationship. At Lulu Is.-UBCPRS a good comparison between SBPM and FDPM results are obtained. 6.3 Conclusions A good comparison was obtained between the results of the Houlsby unloading shear modulus analyzed using cylindrical unloading and the unload-reload modulus. A limited amount of data from McDonald Farm showed that for both methods a long creep phase before a test resulted in higher values, likely a result of consolidation. An excellent comparison was obtained between FDPM and SBPM Gur values. The unload-reload modulus was normalized with respect to Gmax and was shown to attenuate as the magnitude of the cavity strain increased. The normalized unload-reload data was found to be between the laboratory attenuation curves by Seed and Idriss (1970) and Kokusho et al (1982). 126 MCDONALD FARM 1000-X LxJ Cr: 100 -10 0.0001 f IIIIIIII I IIIIIIII 1 |||||||| i 1 1 1 lll| 1 1 1 1 1 II! * Gmax/Su REF FV — Avg. Relationship for Cohesive Soil6 f Seed and Idriss, 1970 ) > -t-+ • Mini i III • •••a UBC SCP +++++ FUGRO CP 'r = Gur/Su REF Ir = Gur/Su REF FV FV -l Millli| I liiilii| i 1 1 1 1 III] 1 1 111111) 1 i i 11 in 0.001 0.01 0.1 1 SHEAR STRAIN y = 2t9 { % ) 10 Fig. 6.7 : Gur/Su R£F vs Shear Strain at McDonald Farm 1 27 LULU IS. UBCPRS SHEAR STRAIN y = 2ev ( % ) Fig. 6.8 : Gur/Su R£F vs Shear Strain at Lulu Is.-UBCPRS 1 28 However, it should be emphasized that the pressuremeter shear strain is the strain at the cavity wall and not the average strain increment in the soil. Three different definitions of the rigidity index were compared. The Houlsby unloading rigidity index and Ir calculated using Gur divided by the reference Su ranged between 75 and 200 for most FDPM test. On average the Houlsby unloading Ir was slightly higher than Ir calculated using Gur and the reference Su. The rigidity index calculated using Gmax and the reference Su produced values ranging from approximately 100 near the ground surface at Lulu s.-UBCPRS to 1000 at Langley Lower 232 and McDonald Farm. The rigidity index calculated using Gmax appears to be inversely proportional to the organic content and overconsolidation ratio. At McDonald Farm , the normally consolidated soil is relatively homogeneous over the depth range tested with Ir constant and approximately equal to 1000. The rigidity index calculated using Gur and the reference Su was shown to attenuate with increasing shear strain in a similar manner to the Seed and Idriss (1970) average relationship for cohesive soils. An excellent comparison was obtained between the SBPM and FDPM Ir values at Lulu Is.- UBCPRS. 129 CHAPTER 7 STRESS HISTORY AND IN SITU HORIZONTAL STRESS 7.1 Reference Overconsolidation Ratio The results of laboratory tests (Ladd et al, 1977) and critical state soil mechanics concepts have shown that the normalized undrained shear strength can be related to the overconsolidation ratio ( OCR ) using the following expression : (S/er'j - ( S /cr ' ) * OCRA 7.1 v w vo 'oc v u' vo 'nc ' The OCR ratio is defined in terms of effective vertical stress ( OCR = crp'/CTvo' ) and A is the plastic volumetric strain ratio. For this study the reference OCR is obtained by matching field vane data to the results of oedometer tests on tube samples as shown in Fig. 7.1. For the Lower Langley 232 site a plastic volumetric strain ratio of A - 0.9 produces a good fit between the field vane and oedometer results. This is a reasonable value when compared to a review of nine well documented clays by Jamiolkowski et al (1985) which indicated that for field vane shear conditions, A ranges between 0.77 and 1.51 with a mean of 1.03. 7.2 Stress History The reference OCR is correlated against the results of FDPM and seismic piezocone tests at the Lower Langley 232 site between the depths of 2 and 13 m. The variation in Gmax/Su with OCR is shown in Fig. 7.2 130 LANGLEY LOWER 232 OCR 5 J L 10 J L J L 5H 1(H x i— CL 20 H 25 « > > * # « « « * « * * _L_ OCR >»» OEDOMETER TESTS ***** FIELD VANE SANDY SILT LAYER I (s>;)J (S«/aw)M =.26,A = 0.9 J I L J L Fig. 7.1 : Stress History from Field Vane at Lower Langley 232 131 while the variation in the normalized limit pressure and cone bearing with OCR is shown in Fig. 7.3. In Fig. 7.2 the rigidity index is calculated by using the average dynamic small strain shear modulus, Gmax, and the average undrained shear strength, Su. The field vane Su is used since it is felt to be more reliable and consistent than the limited number of FDPM Su values obtained. The rigidity index initially increases slightly and then decreases in a linear fashion as the OCR increases. This result is similar to the trend observed for Boston Blue clay in Fig. 4.16. In Fig. 7.3 , the correlation between ( ^20'ffvo )/aVo' or ( qt-avo )/<7vo' a*id OCR are compared. It is apparent that the FDPM correlation increases less rapidly than the CPT correlation and appears to level off as the OCR increases. The CPT correlation increases in a consistent manner except for a slight dip at an OCR of approximately 2.8. Also included for comparison purposes is the curve produced using N^t*Su/<7vo' where Su is from the field vane. A good comparison is obtained except that the plot of N^t*Su/aVQ' is more concave up shaped. 7.3 Reference In Situ Horizontal Stress The determination of the in situ horizontal stress, ^no, using in situ test methods is a challenging task. In soft clays, the SBPM test is perhaps the most promising method of determining anQ. Unfortunately, high quality SBPM tests were not performed during this research. The dilatometer test also yields reasonable values of KQ and hence ano in soft and medium non-cemented clays ( Jamiolkowski et al, 1985 ). Since several dilatometer test profiles were made at the research sites, the 132 LANGLEY LOWER 232 1200 C/? 900-x o E UJ 1 — 'T 1 - I 1 II" • * S„ FROM FIELD VANE * * * * * • /(Su/oW)oo> OCR = USu/OnJ ^ I (S„/One = .26. A = .9 a OCR • t 7 • • 10 Fig. 7.2 : Variation in Gmax/Su with OCR at Langley Lower 232 15-0-} 10-b -g 5-i t) LANGLEY LOWER 232 » 12.5 1~ + ***** {jX~0^)/0^o » "ao UfcJU SOr Tests OCR ~i—i—r 7 8 9 10 Fig. 7.3 Variation in (P20-Svo>/Svo' and <*t-Svo>/Svo' with OCR at Langley Lower 232 133 dilatometer KQ and hence anQ was chosen as the reference cr^o' Marchetti's (1980) correlation : KQ - ( KD/1.5 )0-47 - 0.6 7.2 is used to calculate KQ. Brooker and Ireland's correlation between KQ obtained during consolidation tests and OCR and plasticity index is also included for comparison purposes. 7.4 In Situ Horizontal Stress The in situ horizontal stress and therefore KQ calculated from FDPM tests is shown in Fig. 7.4. The KQ values are obtained using the empirical approach as suggested by Lacasse and Lunne (1983). The practical limit pressure is defined as the expansion pressure at 20 % cavity strain and Su and Ir are from the Houlsby Unloading analysis. Several observations can be made : 1. ) The FDPM KQ values are in general much too high. 2. ) The FUGRO CP with a pressuremeter L/D of 10 produced KQ values which were lower than the UBC SCP with a L/D of 5. 3. ) The FDPM KQ values are highly sensitive to the Su used. The KQ values are in part too high because of the low Su obtained using the Houlsby Unloading analysis ( see Chapter 5 for details ). The results also appear to indicate that spherical expansion theories may be more appropriate for the analysis of FDPM tests with low L/D ratios. The same technique is used to obtain KQ from SBPM tests except that the field vane Su and a constant Ir equal to 200 are used. The results for McDonald Farm in Fig. 7.5 indicate a fairly good correlation between MCDONALD FARM K. 0.0 0.5 1.0 15 _l I I I i I I J i I L 1.5 0.0 20-Q 25-30-35-J I l_ UBC SCP CYLINDRICAL UBC SCP SPHERICAL oaaaa FUGRO CP CYLINDRICAL »»t>t>» FUGRO CP SPHERICAL DILATOMETER Morchetti flflBO) Brooker ft Irelartd(l965). PI=1S. OCR-1 —I—I I—I I I I I I I I I I t 5-i 10" 15-LULU IS. UBCPRS 1.0 2.0 _l_ I I I I I I I L 0.0 + + • • ••••• UBC SCP CYLINDRICAL +++++UBC SCP SPHERICAL DILATOMETER Brooker ft R Morchetti (1980) lreland(1965). PI-21. OCR-1 J I I I I 1 I i ' 5-10-15-20-LANGLEY LOWER 232 K. 1.0 i 2.0 I I I 3.0 L_L_ 4.0 20-FDPM K, - — PL-^CZ+mJ/J^Cl+tnLj-u, Ir and S, Houlsby Unloading , m - 1 CYLINDRICAL m - 2 SPHERICAL Ko\047 Brooker and Ireland (1965). PI-20 •••••UBC SCP CYLINDRICAL tint UBC SCP SPHERICAL DILATOMETER MarchetM (1980) -J—I—I—I I I—I I I I I IIII DILATOMETER K» - ^—j - 0.6 u Fig. 7.4 : FDPM K Values Obtained Using Empirical Method \ 135 MCDONALD FARM K0 0.0 0.5 1.0 15 20-25-Q_ Lul Q 30 35 J I I I I I I 1 I IIIII 1.5 *#*#• Hughes SBPM CYLINDRICAL DILATOMETER Morchetti (1980) Brooker & lreland(1965;. Pl=15. 0CR=1 J I I I I I I ' ' ' i i i i SBPM Ko • — ; a*' = PL-Su*(1+lnlr)-u0 . If=200 . SU-FV / K \047 DILATOMETER - f — J - 0.6 Fig. 7.5 : SBPM KQ Values Obtained Using Empirical Method at McDonald Farm 136 the dilatometer and SBPM. When this same technique is used for SBPM tests at the Lulu Is.-UBCPRS extremely low or negative values of KQ are obtained. It is likely that the low SBPM practical limit pressures obtained at Lulu Is.-UBCPRS are the major cause of the poor results. The results indicate that the empirical method of determining KQ is a poor one. This same conclusion was reached by Lacasse and Lunne (1983) when they compared the results of the empirical method to other techniques for high quality SBPM tests. Another technique which may be better suited to determining the in situ horizontal stress from FDPM tests is shown in Fig. 7.6. The dilatometer and FDPM are compared using identical equations for and KpM. From the results at McDonald Farm and the Lulu Is.-UBCPRS, it appears that Kp^ could be correlated to KQ in a similar manner to KD. A poorer comparison of the KD and KpM profiles at the Lower Langley 232 site could be in part due to the long relaxation times employed during testing at this site. Another factor which could cause a difference in the dilatometer and FDPM test profiles is that less stress relaxation likely occurs during dilatometer penetration due to less abrupt change in geometry between the tip and blade of the dilatometer. 7.5 Conclusions Two methods were presented which relate parameters obtained from a seismic cone pressuremeter sounding to stress history. An excellent correlation was obtained between the rigidity index defined as G ° J max divided by the field vane Su and the OCR. The second method involved correlating the normalized cone bearing and the pressuremeter practical limit pressure to the OCR. The normalized cone bearing and to a lesser MCDONALD FARM LULU IS. UBCPRS LANGLEY LOWER 232 Ko & KPM KD & Km Ko & KPM 10 2.0 3.0 0.0 1.0 2.0 3.0 4.0 0.0 Jn an nn DILATOMETER KD = (P0-U0)/<J„' FDPM Kp*, = (P0-u0)/o", Fig. 7.6 : Comparison of Dilatometer KD and FDPM KpM Values 138 extent the practical limit pressure showed a fairly consistent increase as the OCR increased. Both techniques are promising and should be investigated further. The determination of in situ horizontal stress is difficult. Using the "empirical" method described by Lacasse and Lunne (1983) , the anQ was estimated for FDPM test results assuming both cylindrical and spherical cavity expansion theory. The method has several drawbacks in that it is sensitive to the Su and Ir chosen. Furthermore, the expressions for cavity expansion are based on the assumption that the stress conditions are known at the beginning of a test. When compared to laboratory and dilatometer KQ values, the FDPM KQ results for cylindrical cavity expansion and to a lesser extent spherical cavity expansion are much higher. In summary, the results indicate that the "empirical" method of calculated the in situ horizontal stress is a poor technique for FDPM tests. 139 CHAPTER 8  CONCLUSIONS AND RECOMMENDATIONS The main objective of this research was to interpret and evaluate the results of FDPM tests performed as part of a cone pressuremeter sounding. The following sections summarize the most significant findings of this research. 8.1 Factors Affecting the Interpretation of the FDPM Test FDPM test results are influenced by both the design and performance of the pressuremeter and the procedures used during an actual test. Important equipment related considerations which were discussed are compliance, strain arm design and calibrations, membrane correction curves and pressuremeter L/D ratio. Compliance resulting from the compression of the lantern strips and rubber membrane was investigated for the UBC SCP by inflating the pressuremeter inside a 44 mm diameter split cylinder. It was shown that although the actual deflections due to compression are small, the strains recorded are significant because of the small diameter of the UBC SCP. Despite the potential problems in interpretation which compliance can cause, it is felt that in cohesive soils, compliance has only a minor effect on test results due to effective stress conditions which remain approximately constant throughout a test. The design of the pressuremeter strain arms can have a significant effect on especially the initial portion of the pressuremeter expansion curve. For the UBC SCP, an improvement in the design of the strain arms appeared to eliminate apparent outward deflections for a fully deflated 140 pressuremeter thereby allowing a more rational interpretation of the pressuremeter expansion curve. The importance of the L/D ratio was discussed in Chapter 4. Comparisons of the limit pressures from tests with the Fugro CP having a L/D ratio of 10 and the UBC SCP having a L/D ration of 5 indicated that higher limit pressures are obtained with the UBC SCP. This is to be expected since according to cavity expansion theory, the limit pressure for spherical cavity expansion is greater than that for cylindrical cavity expansion. It was also postulated that the insertion of a FDPM will create a zone of failed soil surrounding the probe which will result in a subsequent pressuremeter expansion which shows a greater deviation from the ideal cylindrical expansion when compared to a SBPM probe with an identical L/D ratio inserted with little disturbance. Several important considerations which relate to test procedures are the amount of relaxation time allowed before a pressuremeter test is performed, the disturbance created during pressuremeter insertion and the strain rate employed during a pressuremeter test. The amount of relaxation time allowed has a significant effect on the measured lift off pressure for FDPM tests due to high excess pore pressures and subsequent high pore pressure gradients created by the insertion process. It was shown for a limited number of tests with the UBC SCP that the lift-off pressure decreased substantially as the length of relaxation time was increased. The shape of the pressuremeter expansion curve also appears to be affected by the length of relaxation time allowed. For tests with relatively longer relaxation periods, the pressure expansion curves are steeper possibly being a result of consolidation occurring before a test is started. 141 A substantial but repeatable amount of disturbance is created by FDPM insertion. A variable amount of disturbance often results from SBPM insertion due to the difficulty in inserting the SBPM probe without disturbing the surrounding soil. In general, the variability of the SBPM lift-off pressures were much greater than the FDPM results suggesting that the degree of disturbance created by SBPM insertion was variable. Also interesting to note were the good comparisons obtained between dilatometer and FDPM lift-off pressures and the FDPM practical limit pressure and the dilatometer P^ pressure. Most interpretative methods used to analyze the pressuremeter test in cohesive soils are based on the assumption that the soil remains undrained during a test. For the relatively permeable cohesive soils tested for this research, it is felt that the high gradients of excess pore pressure created some partial consolidation during a test. The results of pressuremeter tests at McDonald Farm appear to confirm this in that slower tests resulted in a higher undrained shear strengths for tests analyzed using Windle and Wroth's average strength method. A limited number of test results also indicate that the unload-reload modulus increases in proportion to the length of the creep phase before the unload-reload test is begun. 8.2 Parameters Obtained From FDPM Tests 8.2.1 Undrained Shear Strength A good comparison was obtained between FDPM and SBPM undrained shear strength values analyzed using the Windle and Wroth average strength analysis of the pressuremeter expansion curve. For most tests the pressuremeter produces higher Su values than the field vane. It 142 should be noted that in a strict sense, the use of cavity expansion theory for the analysis of FDPM tests is incorrect due to the unknown stress conditions caused by soil disturbance. A limited number of FDPM tests performed after a relatively long period of relaxation all resulted in much higher Su values indicating that the dissipation of excess pore pressures has a significant effect on the calculation of FDPM undrained shear strengths using cavity expansion theory. The Houlsby analysis of the contraction curve in general results in undrained shear strengths which are generally lower than the field vane Su. Compared to the other theoretical methods, the Houlsby Su values are less variable and exhibit less scatter. The merits of the analytical techniques used to calculate the undrained shear strength are difficult to assess since Su will be affected to varying degrees by the factors discussed in section 8.1 as well as the technique chosen. The Windle and Wroth average strength method appears to be a reasonably sound method of calculating Su for the following reasons ; the SBPM and FDPM results are similar, and the reference and FDPM Su values exhibit similar amounts of scatter and trends with depth. The Houlsby unloading technique appears somewhat promising in that it provides a conservative estimate of Su which does not appear to be affected by the length of relaxation time allowed. A moderately good correlation was obtained between the traditional empirical method for calculating the pressuremeter Su and the field vane Su in normally consolidated soils. At McDonald Farm and Lulu Is.-UBCPRS the FDPM N value calculated using the following equation : N - ( P2Q - PQ ) / Su pv 8.1 143 ranged between approximately 2.25 and 3.75 for tests with short relaxation periods. The average N value was 2.8 for McDonald Farm and 2.9 for Lulu Is.-UBCPRS. The dependence of N on soil characteristics is thought to be similar to that shown for and N^u. 8.2.2 Shear Modulus and Rigidity Index An excellent comparison between FDPM and SBPM unload-reload shear moduli were obtained. The unload-reload shear modulus was normalized with respect to Gmax and was shown to attenuate as the magnitude of the cavity strain increment increased. A good comparison was also obtained between the Houlsby unload shear modulus and Gur. A drawback with the Houlsby shear modulus is that it is difficult to associate a strain increment level with the shear modulus. Three different definitions of rigidity index were compared. The Houlsby unloading rigidity index for most FDPM tests ranged between 75 and 200 and on the average was slightly higher than Ir calculated using Gur divided by the field vane Su. The rigidity index calculated using Gmax divided by the field vane Su produced values as high as 1000 at McDonald Farm and Langley Lower 232. All definitions of the rigidity resulted in highly variable results at Lulu Is.-UBCPRS and to a lesser degree at Langley Lower 232. 8.2.3 Stress History and In Situ Horizontal Stress The overconsolidation ratio was correlated to both the pressuremeter practical limit pressure and the cone bearing for data at Langley Lower 232 using the following expression : OCR - f ( (qfc or P20 - aVQ) / aVQ' ) 8.2 144 The normalized cone bearing and to a lesser extent the normalized practical limit pressure showed a fairly consistent increase as the OCR increased. An excellent correlation was obtained between the rigidity index defined as the dynamic small strain shear modulus divided by the field vane Su and the OCR. The rigidity index increased slightly and then decreased steadily as the OCR increased. The in situ horizontal stress and hence KQ was estimated using the equation for the limit pressure assuming both cylindrical and spherical cavity expansion theory. The method has several drawbacks in that it is sensitive to the value of the limit pressure and the undrained shear strength used. Furthermore, the expressions for spherical and cylindrical cavity expansion are based on known stress conditions at the beginning of a test. The Houlsby unloading undrained shear strength and rigidity index was used for the estimation of the in situ horizontal stress for FDPM tests. Spherical cavity expansion theory resulted in the most reasonable values of KQ when compared to dilatometer KQ values using Marchetti's (1980) correlation. 8.3 Recommendations The cone pressuremeter is a promising new in situ testing device which has great potential. A comprehensive amount of data including full displacement pressuremeter, piezocone and seismic data can be obtained during a cone pressuremeter sounding. Recommendations for further research deal with equipment design, test procedures and interpretative methods. 145 1) The cone pressuremeter should have a pore pressure sensor next to the probe. This will allow a better estimation of the stress conditions prior to a test. 2) Consideration should be given to constructing a cone pressuremeter with a low L/D ratio and using spherical expansion to analyze the results. 3) The effect of varying lengths of relaxation time prior to a test should be further investigated. This is important for both theoretically and empirically based interpretative methods. It may be beneficial to establish guidelines for the length of relaxation time prior to a FDPM test similar to those for a dilatometer test. 4) Further research should be directed towards trying to quantify the effects of consolidation and strain rate on FDPM curves. 5) The Houlsby unloading analysis appears to be a very promising method of determining both the undrained shear strength and shear modulus. Further work should be done in a variety of cohesive soils to validate this method and to compare the results to undrained shear strengths obtained using other in situ and laboratory methods. 6) Further research should be directed towards trying to establish FDPM correlations using parameters similar to those used for the dilatometer test. 7) Further research should focus on relating the unload-reload shear modulus to a strain increment level and to compare Gur to the results of other cyclic and monotonic laboratory tests. 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(1972): "Consolidated-undrained Direct Simple Shear Tests on Saturated Clays". MIT Research Report, R72-82. Landva.A. (1986): "In Situ Testing of Peat". Proceedings of ASCE Conference on Use of In Situ Tests in Geotechnical Engineering, Blacksburg, Virginia, Blacksburg, Virginia, June, pp. 191-205. Lutenegger,A.J. (1988): "Current Status of the Marchetti Dilatometer Test". Proc. of the First International Symposium on Penetration Testing, ISOPT-1, Orlando, March, Volume 1, pp. 137-155. Marchetti,S. (1980): "In Situ Tests by Flat Dilatometer".Journal of the Geotechnical Engineering Division, ASCE, Volume 106, No. GT3, pp. 299-321. Petsonk.A.M. (1985): "A Device for In Situ Measurement of Hydraulic Conductivity". Presented to AGO Symp. on Advances in Hydraulic Testing and Tracer Methods, San Francisco. 150 Prevost.J.H. (1979): "Undrained Shear Tests on Clays". Journal of the Geotechnical Engineering Division, ASCE, Volume 105, No.GTl, pp. 49-64. Prevost.J.H. and Hoeg.K. (1975): "Analysis of Pressuremeter in Strain-softening Soil". Journal of the Geotechnical Engineering Division, ASCE, Vol. 101, No. GT8, pp. 717-732. Rice,A.H. (1984): "The Seismic Cone Penetrometer". M.A.Sc. Thesis, Department of Civil Engineering, University of British Columbia. Robertson,P.K., Hughes,J.M.O., Campanella,R.G., Brown,P. and McKeown.S. (1986): "Design of Laterally Loaded Piles using the Pressuremeter". The Pressuremeter and Its Marine Applications, Second Int. Symp. : ASTM STP 950, J.L. Briaud and J.M.E. Audibert, Eds. American Society for Testing and Materials.21 Robertson,P.K. and Campanella,R.G. (1986): "Guidelines for Use and Interpretation of the CPT and CPTU". Soil Mechanics Series No. 105, Department of Civil Engineering, University of British Columbia. Robertson,P.K., Campanella,R.G., Gillespie,D., andGreig.J. (1985): "Use of Piezometer Cone Data". Soil Mechanics Series No. 92, Department of Civil Engineering, University of British Columbia. Randolph,M.F. and Wroth,CP. (1979): "An Analytical Solution for the Consolidation Around a Pile". International Journal for Numerical and Analytical Methods in Geomechanics. Volume 3, pp.217-229. Robertson,P.K., Hughes,J.M.O., Campanella,R.G. and Sy,A. (1983): "Design of Laterally Loaded Displacement Piles using a Driven Pressuremeter". ASTM STP 835, Design and Performance of Laterally Loaded Piles and Pile Groups, June, Kansas City, Mo. Seed.H.B. and Idriss.I.M. (1970): "Soil Moduli and Damping Factors for Dynamic Response Analysis". Report No. EERC 70-10, College of Engineering, University of California at Berkeley, December. Sully,J.P., Campanella,R.G. and Robertson,P.K. (1988): "Interpretation of Penetration Pore Pressures to Evaluate Stress History in Clays". Proc. of the First International Symposium on Penetration Testing, ISOPT-1, Orlando, March, Volume 2, pp. 993-1000. Suyama.K., Imai.T., and Ohya.S. (1982): "Development of LLT and Its Application in Prediction of Pile Behavior Under Horizontal Load". Proc. Symposium on the Pressuremeter and Its Marine Applications, Paris, pp. 61-67. Windle,D. and Wroth,CP. (1977): "The Use of the Self-Boring Pressuremeter to Determine the Undrained Properties of Clays". Ground Engineering, September, pp. 37-46. Wroth,CP. (1988): "Penetration Testing - A More Rigorous Approach to Interpretation". Proc. of the First International Symposium on 151 Penetration Testing, ISOPT-1, Orlando, March, Volume 1, pp. 303-311. Wroth,CP. (1984): "The Interpretation of In Situ Soil Tests". 24th Rankine Lecture, Geotechnique 34, pp. 449-489. Wroth, CP., Randolph, M.F. , Houlsby, G.T, and Fahey, M. (1984a): "A Review of the Engineering Properties of Soils with Particular Reference to the Shear Modulus". O.U.E.L. Report No. 1523/84, Soil Mechanics Report No. SM049/84. Wroth,CP. (1982): "British Experience with the Self-Boring Pressuremeter". Proc. of the Symposium on the Pressuremeter and Its Marine Applications, Paris, pp. 143-164. Wroth.CP. and Hughes, J.M.O. (1974): "Development of a Special Instrument to Measure the Strength and Stiffness of Soils". Proceedings ASCE Speciality Conference on Subsurface Exploration for Underground Excavation and Heavy Construction, Henniker, NH, pp. 295-311. Wroth,CP. and Hughes,J.M.O. (1973): "An Instrument for the In situ Measurement of the Properties of Soft Clays". 8th ICSMFE, Moscow. APPENDIX I PRESSUREMETER TEST DATA AT MCDONALD FARM 1*3 Site : McDonald Farm Date  27/1/87 Pressuremeter : UBC SCP On Site Location : JAN27 Comments : No piezocone or seismic measurements Strain controlled test Depth Strain Rate Approx. Relaxation ( m ) ( %/min ) Period ( min ) 17.0 8.5 1.5 19.0 9.122.0 8.1 1.5 25.0 7.027.5 7.2 1.5 30.0 7.6UBC SCP 27/1/87 REPLOT 27/10/87 S D Q. £ n n £ •o a> +> o © k. «~ o o 600 500 H 400 300 H 200 H 100 McDonald Farm-17.0m -100 Average Strain % Cavi4y -Strain UBC SEISMIC CONE PRESSUREMETER Site : McDonald Farm -Inf Depth : 17.0 m Date : 27/1/87 LOG CURRENT VOLUMETRIC STRAIN 600 500 H 400 300 200 H UBC SCP 27/1/87 Houlsby Unloading Cyi McDonald Farm—17.0m 5^= 24x5 kPa 100 2 i 1 —r 6 T 8 10 —ln(eo — e ) ©=ncrtural strain UBC SCP 27/1/87 REPLOT 27/10/87 o Q. O i_ n ro £ U O -M O © l_ 1. 0 O 700 600 H 500 H 400 H 300 4 200 H 100 -4 McDonald Farm—Depth=19.0m -100 Average Strain (%) i <5<d> UBC SEISMIC CONE PRESSUREMETER Site : McDonald Form -Inf Depth : 19.0 m Date : 27/1/87 700 650 600 550 500 450 1 10 10* LOG CURRENT VOLUMETRIC STRAIN UBC SCP 27/1/87 McDONALD FARM Houlsby Unloading Cyl D= 19.0m 100 -i o r 1 1 1 1 1—1 1 -i i I 0 2 4 6 8 10 -ln(E0 - E) E=Natural Strain UBC SCP 27/1/87 REPLOT 28/10/87 McDonald Farrn-Depth==22.0rn 800 -i r ~ioo H 1 r-—i 1 1 T 1 1——i 1 1 r -2 2 6 10 14 18 22 Average Strain (%) Cav/i-Vy 5+rain. 16\ UBC SEISMIC CONE PRESSUREMETER Site : McDonald Farm -lnf Depth : 22.0 m Date : 27/1/87 0 £ 3 B n e O O 800 700 4 600 4 500 400 4 300 4 200 4 100 4 UBC SCP 27/1/87 McDONALD FARM Houlsby Unloading Cyl D=22.0M T 2 T = 46.1 IcPa S asrk - 34S Vft ^4u.- 134 6,- 134*5^1 -4.18 MPa 4 6 -In(E0 - E) E=Notural Strain 8 10 0 n 0 0 o o 750 740 730 720 710 700 690 680 670 660 650 640 630 620 610 600 590 580 570 560 550 UBC SCP - 27/1/87 McDonald Farm — 22.0m -2 loo « 5.o5 MP. If 22 N«Ki«4 Strain Data Points UBC SCP 27/1/87 REPLOT 28/10/87 McDonald Farm-Depth=25.0m 900 n r— — Average strain (%) Cavity S+rain UBC SEISMIC CONE PRESSUREMETER Site : McDonald Farm -Inf Depth : 25.CV m Date : 27/1/87 1 10 10 2 LOG CURRENT VOLUMETRIC STRAIN \6£ UBC SCP - 27/1/87 McDonald Farm — 25.0 m -1 1 3 5 7 9 11 13 15 17 19 Nov.W<0 Strain - Data Points Average Strain {%) Cav/rq "Strain. UBC SCP 27/1/87 McDONALD FARM Houlsby Unloading Cyl D=27.5m 1 6 ~240*Su«jl« H-ZMPJ 8 10 -ln(E0 - E) E=Notural Strain Natural Strain Corrected Pressure (kPa) UBC SCP- 27/1/87 REPLOT 28/10/87 McDonald Farm-Depth=30.0m o Q_ x © L. 3 (D 0) £ Q. © O © I-L. 0 o 1100 1000 H 900 -\ 800 H 700 H 600 4 500 -4 400 Cavil j 5^31 A Average Strain (%) UBC SEISMIC CONE PRESSUREMETER Site : McDonald Farm -Inf Depth : 30.0 m Date : 27/1/87 1 10 102 LOG CURRENT VOLUMETRIC STRAIN UBC SCP 27/1/87 Houlsby Unloading Cyi McDonald Farm—Depth=30.0m -ln(EO - E) E=Naturol Strain UBC SCP 27/1/87 MCDONALD FARM D=3O.O m Cavity Strain % Data Points 1^5 Site Date Pressuremeter On Site Location Comments McDonald Farm 7/11/85 FUGRO CP N0V7 No piezocone measurements Quasi-strain controlled test Depth Strain Rate Approx. Relaxation ( m ) ( %/min ) Period ( min ) 16.2 1.1 1-5 18.2 1.919.2 - 1-5 20.2 5.2 1-22.2 5.0 l'-5 1000 86/01/10 DEPTH = 16.2 m. McDONALD FARM CORRECTED FOR MEMBRANE 30 40 CAVITY STRAIN (%) FUGRO CONE PRESSUREMETER Site : McDonald Farm Depth : 16.2 m Date : 10/1/86 LOG CURRENT VOLUMETRIC STRAIN S 86/01/10 DEPTH=16.2 m. McDONALD FARM fugro 16 17 18 19 20 CAVITY STRAIN % o Q. \^ hi OH D V) in hi a: o. Q hi hi OH OH O O 86/01/10 DEPTH=16.2 m. McDONALD FARM fugro 20hl.|oc66-ln I-W61 Gur- 130 2t In l.03*Mn 103381 8 -41 T-10 CAVITY STRAIN % 86/01/10 DEPTH=16.2 m. McDONALD FARM FUGRO HOULSBY UNLOADING CYL 0 2 4 6 8 10 -ln£o-€) r£= NATURAL STRAIN ' 86/01/10 DEPTH=18.2 m. McDONALD FARM Corrected for Membrane 1000 ——— " 900 -800 -CAVITY STRAIN (%) FUGRO CONE PRESSUREMETER Site : McDonald Farm Depth : 18.2 m Date : 10/1/86 600 H i 1 1—i i i i i | 5.303 I 1 1—ryi i i i 1 1- 'i i i i i 1 10 LOG CURRENT VOLUMETRIC STRAIN S 10 •Z3\ o Q. hi or D (/) V) bJ Q. 86/01/10 DEPTH=18.2 m. McDONALD FARM Corrected for Membrane i 1 r~ 21.4 21.8 23 T T~ 23.4 i I CAVITY STRAIN % 86/01/10 DEPTH-18.2 m. McDONALD FARM Corrocted for Membrane CAvrrr STRAIN % 86/01/10 DEPTH=18.2 m. McDONALD FARM FUGRO HOULSBY UNLOADING CYL 4 , 1 1 r— 1 H 1 1 1 1 0 2 4 6 8 10 -In (EO - E) E=NATURAL STRAIN CAVITY STRAIN (%) (8^ FUGRO CONE PRESSUREMETER Site : McDONALD FARM Depth : 19.2 m Date : 10/1/86 700 650 D CL 600 LxJ cr §550 LU CcL CL j< 500 H O r-450 H 400 i 1 1—i i 1 1—i i i i Sg= 584-40O - 8ao kfk 2-303 T 1 1 1 llll| ib LOG CURRENT VOLUMETRIC STRAIN S T 1 1 IIIII 10 86/01/10 DEPTH-19.2 M McDONALD FARM FUGRO HOULSBY UNLOADING CYL 100 -] o _j j 1 -j [— r 1 1 1 0 2 4 6 8 —LN(EO - E) E=NATURAL STRAIN 1000 900 -800 -700 -CAviTY STRAIN (%) I 3o FUGRO CONE PRESSUREMETER Site : McDonald Farm Depth : 20.2 m Date 700 650 o CL •* 600 a: §550 LLI a: Q-^ 500 o 450 glared-4OQ + + + • + 400-j 1 10 LOG CURRENT VOLUMETRIC STRAIN CORRECTED PRESSURE ( kPa ) o II Z I XI f 73 > 86/01/10 DEPTH=22.2m McDONALD FARM Corrected for Membrane MF3V2r~U 200 -100 -0 _T_.. 10 .... f "1 20 '"I" 30 (CAVITY STRAIN (%) FUGRO sfte : McDonald Farm CONE PRESSUREMETER Date : 10/1/86 Depth 22.2 m LOG CURRENT VOLUMETRIC STRAIN * 0 DEPTH=22.2m McDONALD FARM FUGRO HOULSBY UNLOADING CYL 5u5pU =- 33.8 IcPa I 61 - I36*5ucyl =6.12 Nfli 4 6 _! j 8 10 —LN(E0 - E) E=NATURAL STRAIN 86/01/10 DEPTH=22.2m McDONALD FARM FUGRO 560 550 540 530 -i 520 -1 510 \ / \ / l^icAA^= .23% r—[— 3.6 ~i r 3.8 T 1 T" 4 4.2 CAVITY STRAIN % o Q. hi tY. D U) V) hi tn CL Q Id LJ a: or o o 710 700 -} 690 "1 680 -t 670 H 86/01/10 DEPTH=22.2m McDONALD FARM FUGRO 660 "i—i—r—r I \ l \ i V Hnl.2274-Wil.725ll -13.6 MPa ? A^Aj - 0.29% /1 / 22 __1 j r.._f ; j 1 r 1 j 22.2 22.4 22.6 22.8 23 23.2 23.4 23.6 23.8 24 CAVITY STRAIN % Site : McDonald Farm Date  18/10/83 Pressuremeter : Hughes SBPM On Site Location : 0CT18 Comments : Strain rate is rough approximation Stress Controlled Test Depth Strain Rate Approx. Relaxation ( m ) ( %/min ) Period ( min ) 16.75 1 1-5 17.7518.75 1 1-5 19.75 0 1-20.76 1 1-5 21.76 0 1-22.76 1 5 23.76 0 . 1-5 24.76 10 1-25.76 5 McDONALD FARM Hughes SBPM D= 16.75 rn CAVITY STRAIN ( % ) 199 HUGHES SBPM 10/18/83 McDONALD FARM D « 16.75 m ++++ ++++++ (5,= 3?k 3* .02.38 T 1 1 1 1 i 1 1 1 1—i 1—i 1 1 1 1 1 r 10 12 14 16 18 20 O Data Points Cavfty Strain (SQ + Arnold Curv» FH fro HUGHES SBPM 18/10/83 Mod Arnold McDONALD FARM D" 16.75 m Cavtty Strain W SELF - BORING PRESSUREMETER Site : McDonald Farm - JH Depth : 16.75 m Date : 10/18/83 1 10 10* LOG CURRENT VOLUMETRIC STRAIN % McDONALD FARM SBPM Feb. /84 D« 16.75 m Houlsby Unloading Cyl o a. (0 CO tt. 600 500 -400 H 300 ~t 200 100 -58o Su^l - 583 ka P j 560- C-^ - 32 -2^4 6 o 8 -ln(E0 - E) E«Natural Strain McDONALD FARM Hughes SBPM D= 17.75 m T 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1! 0-j—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i 0 5 10 15 20 CAVITY STRAIN ( % ) 800 HUGHES SBPM 10/18/83 McDONALD FARM D = 17.78 m 700 H 600 H 500 H 400 H 300 Jf 200 .4.^ + 4-+ + + + +  +++^ + + + + ° ° cS^ 4It 5«l a - .CM5Z. ~i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—r 2 4 6 8 10 12 14 16 18 20 D Dote Points Cavtty Strain (*) 4- Arnold Curv* Fit Cavfty Strain (X) 10<o SELF - BORING PRESSUREMETER Site : McDonald Farm - JH Depth : 17.75 m Date : 10/18/83 LOG CURRENT VOLUMETRIC STRAIN % McDONALD FARM SBPM FEB. /84 D= 17.75 m Houlsby Unloading Cyl £43 o o. 0 / 2 4 6 8 10 -ln(E0 - E) E=NAtural Strain McDONALD FARM Hughes SBPM D= 18.75 m o O 200 ~i—i—i—i—j—i—i—i—i—1—i—i—i—i I " ' 1 r 5 10 15 CAVITY STRAIN ( % ) 900 HUGHES SBPM 10/18/83 McDONALD FARM D = 18.75 m 800 H 700 600 500 H 400 H 300 ++++ a - Oil! b= .C.G2-T-—t— 10 —r-12 —r— U 16 -r 0 2 D Data Points T 4 -r 8 18 20 CavHy Strain (*) + Arnold Curve Fit Covfty Strain (X) 9-w 1 10 10* LOG CURRENT VOLUMETRIC STRAIN * o 0-2 B 0) 2 Q. 900 800 700 600 500 H 400 H 300 200 4 100 -4 McDONALD FARM SBPM FEB. /84 D= 18.75 m Houlsby Unloading Cyl 823 - + VP Cwo = 8Z!^ 4^> 8 -ln(E0 - E) E=NaturaI Strain McDONALD FARM Hughes SBPM D= 19.75 m 1000 -i—-|—i—i—i—i—i—i—i—i—i—r—i—i—i—i—i—i—i—i—I 0 f i—i—i—i—I—i—r—i—i—|—~i—i—i—i—j—i—i—i—i—I 0 5 10 15 20 CAVITY STRAIN ( % ) 3-\4 a & I 3 a L. 8 900 800 700 H 600 H 500 H 400 300 HUGHES SBPM 10/18/83 McDONALD FARM D » 19.76 m ++++ <5V= 640 I Ko^eA /Wold ^Ll^ax" 101 KPa -r-2 4. -r 8 -T— 10 —i—r 12 1+ 16 -1—r 18 20 • Data Polnta Cavity Strata (X) + Arnold Curve Fit SELF - BORING PRESSUREMETER Site : McDonald Form - JH Depth : 19.76 m Date : 10/18/83 550 H 1 1—i i i i i i | 1—-i » iii'i' 1 0 1 LOG CURRENT VOLUMETRIC STRAIN % McDONALD FARM SBPM FEB. /84 D=19.76 m Houlaby Unloading Cyl o H —i 1 1—:—i——i 1 1 1 r 1 0 2 4 6 8 10 -ln(E0 - E) E=Natural Strain 915 o I I £ 3 • 0 o 900 800 700 -4 600 500 H 400 41 300 HUGHES SBPM 10/18/83 McDONALD FARM D => 20.76 m +++ + + ^ + + + ~ 1 1 1 b- -0022_ 6) = 4to T 1 1 1 1 1 1 1 1 1 1 1—1 1 1 1 1 1 r 2 4 6 8 10 12 14 16 18 20 D Data Points Cavity Strain (%) + Arnold Curve Fit 7.7-0 Ccvhy Strain (X) SELF - BORING PRESSUREMETER Site : McDonald Farm - JH Depth : 20.76 m Date : 10/18/83 850 i 1—I—T—rr-n o or ZD CO CO Ld cr a. Q 800 H -t H j 750-i 700 H 450 10 102 LOG CURRENT VOLUMETRIC STRAIN % McDONALD FARM SBPM FEB. /84 D=20.76 m Houlsby Unloading Cyl 0 2 4 6 8 —ln(EO — E) E=natural strain <rc£ 2lA 900 800 -\ 700 4 600 500 400 H 300 HUGHES SBPM 10/18/83 McDONALD FARM D = 21.76 m +++++ \o =- .00:14 Arnold .ScW* 100^3 -i—i—i—i—i—i—r—i—i—'—'—1 1 r 2 4 6 8 10 12 1 + 16 1—i—r 18 20 D Data Pointa Cavity Strain (X) +• Arnold Curva Fit 1%Z o 92 HUGHES SBPM 18/10/83 Mod Arnold McDONALD FARM D-21.76 m Covtty Strain (X) SELF - BORING PRESSUREMETER Site : McDonald Farm - JH Depth : 21.76 m Date : 10/18/83 1 T [-T/TTTT 900 850 —i T——i 1—r-i i i n -t 800 H: -1 D CL H -j 750 3 LU J cr: 4 i —« co 700-CO LU or Q_ 650-< h-o — r— 600 -i 550-i 500 T—r~T~mrr i—i—i r rrr, 10 102 LOG CURRENT VOLUMETRIC STRAIN % 900 McDONALD FARM SBPM FEB. /84 D=21.76 m Houlsby Unloading Cyl 833 800 700 4 Q. l_ 3 CO Of) (9 1_ Q. 600 500 400 4 300 200 4 Cfhp. g33-(~54) -54 z - 3eo KPa 5 100 2 4 6 8 -ln(E0 - E) E=Natural Strain McDONALD FARM Hughes SBPM D=20.75 m i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—i 1 i i i i i i—i—i—i—|—i—i—i—i—|—i—i—i—i—j O 5 10 15 20 CAVITY STRAIN ( % ) I a 0. 5 900 800 H 700 600 500 400 300 HUGHES SBPM 10/18/83 McDONALD FARM D - 22.76 m ++ + +. + + + qi + + + + 65- 840 £3 = IZ •wax (3r- kPd 150 KPa T 1 1 1 1 1 1—1—1 1 1 1 1 1 1 1 1 1 r~ 2 4 6 8 10 12 14 16 1B 20 • Data Polnta Covfty Strain (X) + Amotd Curve Fit S13 0 HUGHES SBPM 18/10/83 Mod McDONALD FARM D=22-76 m SELF - BORING PRESSUREMETER Site : McDonald Farm - JH Depth : 22.76 m Date : 10/18/83 LOG CURRENT VOLUMETRIC STRAIN % McDONALD FARM SBPM FEB 84 0=22.76 m HouW3byJJrac^^ _ln(EO - E) E=NoturaI Strain McDONALD FARM Hughes SBPM D=23.75 m 1000-1—i—i—i—i—i—i—i—i—i—i—> « 1 1 1 1 1 1 r~I o CL LU cn ZD to CO LU cr: Q. cr o o 800 H 600 H 400 200 -t 0 a l_l I • I a. HUGHES SBPM 10/18/83 Vk DONALD FARM D « 23.76 m 300 H 200 4 ioo H b = .-O0Z2. 12 ++++ + +-4- + + + +S + HockW Arnold 12.0 KPa n Data Points Cavity Strain (X) + Arnold Curve Frt ^3^ HUGHES SBPM 18/10/83 Mod Arnold McDONALD FARM D=23.76 m 130 -i 0 -j 1 1 1 1 1 1 1 j 1 1 1 1 1 r 1 T 0 2 + 6 8 10 12 U 16 CovHy Strain (5Q SELF - BORING PRESSUREMETER Site ..McDonald Farm - JH Depth : 23.76 m Date : 10/18/83 900 I T 1 1 TrTTTJ ~i 1—i7-T-n-r-rrj 850 H o CL 800-i 4 6u 750^ -^3.9 - 500 -1l<U k& LU cr: 3 CO 700 co LU cr: CL . 650 H 4 3 o Q. CD i_ 3 01 0) CP l_ CL MCDONALD FARM SBPM FEB 84 D=23.76 m Houlsby Unloading Cyl 836 900 -• 800 -+ 700 - / + 600 -500 -F 400 -300 -200 -100 -n -—-A- r— 1 • —, 1 1 ~i r— 8 -ln(E0 - E) E=Natural Strain <b<ct 23 9 HUGHES SBPM 10/18/83 McDONALD FARM D - 24.76 m 1 "I II 1—i—i : i—i—i—i—i—i—i—i—i—i—i—i—i—i—i—r 0 2 4 6 8 10 12 14 16 18 D Data Points Cavity Strain (*) + Arnold Curve Fit SELF - BORING PRESSUREMETER ,u Depth :24.76 m Date : 10/18/83 Site : McDonald Farm - JH Depth 1000-r i TTT\ 10* ' L0G CURRENT VOLUMETRIC STRAIN % McDONALD FARM SBPM feb 84 D=24.76 m Houlsby Unloading Cyl 481 left. 2 4 -ln(EO - E) E=Natural Strain T 6 McDONALD FARM Hughes SBPM D=25.75 m i—i—i—i—|—i—i—i—i—|—i—i—i—i—|—i—i—i—r 5 10 15 20 CAVITY STRAIN ( * ) . •MA HUGHES SBPM 10/18/83 McDONALD FARM D - 25.76 m 0.9 H 0.8 H 0.7 H 0.6 -1 0.5 H 3 3 0.4 ++++ +•+ ©> 68a 62.= 833 ^ 4 b - .0019 T—1 1 1 1 1—1 1—1 1 1 1 1 1 1—i 1 1 r 2 4 6 8 10 12 U 16 18 20 • Data Points Covfty Strain (X) + Arnold Curve Fit SELF - BORING PRESSUREMETER Site : McDonald Farm - JH Depth : 25.76 m Date : 10/18/83 HUGHES SBPM 18/10/83 Mod Arnold McDONALD FARM D=*25.76 m . Pressure ( kPa ) (Thousands) £4T APPENDIX II PRESSUREMETER TEST DATA AT LULU IS. - UBCPRS £46 Site : Lulu Is - UBCPRS Date  3/4/87 Pressuremeter : UBC SCP On Site Location : APR3 Comments : No seismic or piezocone data Strain Controlled Test Depth Strain Rate Approx. Relaxation ( m ) ( %/min ) Period ( min ) 3.0 11.1 1.5 4.0 11.24.8 10.8 1.5 6.35 10.67.9 10.6 1.5 9.4 12.410.9 10.3 1.5 12.4 10.314.0 9.3 1.5 UBC SCP 3/4/87 REPLOT 26/10/87 D=3.0 M Lulu Ts - UBCPRS ^7~V .++ +rH+ 4f»-+ + + + + + T~ r 8 12 T 1-16 20 C-/VMTY STRAIN % UNCOR + COR COR PRESSURE (kPa) a ARM1 + ARM2 • ARM3 9.5 \ UBC SEISMIC CONE PRESSUREMETER Site : LuluB-UBCPRS- Inf Depth : 3.0 m Date : 3/4/87 Strain UBC SCP 3/4/87 HOULSBY UNLOADING CYL 0 2 4 8 8 10 -ln(E0 - E) E»Notura! Strain 0 CD i_ m m CD i_ Q. 300 250 ~\ 200 -j 150 H 100 50 H -50 UBC SCPM 3/4/87 REPLOT 26/10/87 Annacis Pile D=4.0 m AnnSc^ Pile <= Uda Ts-OBCPf^ uncor Infinitesimal Strain % + cor 18 22 7J UBC SCPM 3/4/87 REPLOT 26/10/87 Annacis Pile D=4.0 m -40 0 40 80 120 160 Cor Pressure (kPa) • arm1 + arm2 O arm3 UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile - Inf Depth : 4.0 m Date : 3/4/87 10 ~1 1 10 10 s LOG CURRENT VOLUMETRIC STRAIN + UBC SCPM 3/4/87 REPLOT 26/10/87 ANNACIS PILE D=4.8 M ANNKI5 PIL£~ LuluXs-UBcP^ 26o -. • , -60 H 1 r , 1—-1 1 1 1 1 1 1 r 0 4 8 12 18 20 24 INFINITESIMAL STRAIN % CCAVITV) UNCOR + COR UBC SCPM 3/4/87 REPLOT 26/10/87 ANNACIS PILE D=4.8 M i t > w-» >• S o I -IIII I I I I 1 1 I I I 1 1 1 1 1 i -50 -30 -10 10 30 50 70 90 110 130 150 COR PRESSURE (KpA) O ARM1 + ARM2 • ARM3 UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile - Inf Depth : 4.8 m Date : 3/4/87 10 "1 1 10 102 LOG CURRENT VOLUMETRIC STRAIN + Corrected Pressure ( kPa ) -iMU>0lOlM00tDO~'M0ifOI01vJC0(OO ooooooooooooooooooooo o hi (Z D V) in u tr o. UBC SCPM 3/4/87 REPLOT 26/10/87 ANNACIS PILE D=6.35M AWNAC15 Pll_£- Lulu I<S USCPRS INFINITESIMAL STRAIN % Ccavi+j) UNCOR + COR <5^ E E c o o e Q 0.5 0.4 4 0.3 4 0.2 4 0.1 4 -0.1 UBC SCPM 3/4/87 REPLOT 26/10/87 Annacis Pile D=6.35 M 1° -40 0 O arm1 40 80 120 160 Cor Pressure (kPa) arm2 • arm3 *> c • * •4J 2^3 UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile - Inf Depth : 6.35 m Date : 3/4/87 10 -1 1 10 102 LOG CURRENT VOLUMETRIC STRAIN + Average Strain + Corrected Navfu-ral S+rain UBC SCPM 3/4/87 HOULSBY UNLOADING CYL AN NAC IS PILE D=>6.35M 20 4 0 -J , 1 1 1 1 f 1 1 1 1 0 2 4 6 8 10 -ln(E0 - E) E=NATURAL STRAIN UBC SCPM 3/4/87 REPLOT 26/10/87 uncor Infinitesimal Strain % + cor E E c o o H— o Q 0.5 0.4 0.3 -i 0.2 0.1 0>0 ' -0.1 UBC SCPM 3/4/87 REP LOT 26/10/87 ANNACiS PILE D=7.9m / 4/ M - ... H— .... /// ii! St-. a ^~4i -40 40 80 120 ~r ft ft ^* 3 IS — • arm1 Corrected Pressure kPa + arm2 O ARM3 160 O UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile - Inf Depth : 7.9 m Date : 3/4/87 10-1 1 10 102 LOG CURRENT VOLUMETRIC STRAIN + UBC Seismic Cone Pressuremeter-3/4/87 Annacis Pile Sfte-Depth=7.9m 240 -, :  230 -j 160 4 1 1 1 1 1 1 1 1 6 7 8 9 0 Average Strain (%) + Corrected NaWral S+rain* UBC SCPM 3/4/87 HOULSBY UNLOADING CYL Annacis Pile D«=7.9 m o H 1 r~ 1 1 1 r— 1 1 1 1 0 2 4 6 8 10 -!n(EO - E) E=Noturol Strain UBC SCPM 3/4/87 REPLOT 26/10/87 ANNACIS PILE D=9.4m 400 —i 0 4 8 12 18 20 24 Infinitesimal Strain % UNCOR + COR UBC SCPM 3/4/87 REPLOT 26/10/87 ANNACIS PILE D=9.4 m IP—B—~_ ;P K-- - .,./^-*/ 1 r-. — —H i 1 1 1 1 11 1 1 - 1 1 -40 0 40 80 120 160* 200 • ARM1 COR PRESSURE (KpA) .+ ARM2 O ARM3 2.7-3 UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile - Inf Depth : 9.4 m Date : 3/4/87 LOG CURRENT VOLUMETRIC STRAIN + UBC SCPM 3/4/87 HOULSBY UNLOADING CYL Annacis Pile D=9.4 m Su- \A>°S Vfo spk 6 10 -ln(E0 - EO) E=Notural Strain UNCOR Infinitesimal Strain % + COR UBC SCPM 3/4/87 REPLOT 26/10/87 ANNACIS PILE D= 10.9m 0.5 0.4 -0.3 0.2 -0.1 0.0 -0.1 -40 120 • ARM1 COR PRESSURE (KpA) + ARM2 O ARM3 UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile - lnf Depth : 10.9 m Date : 3/4/87 i—r i i i i T—i—IIII 1 10 10* LOG CURRENT VOLUMETRIC STRAIN Corrected Pressure (kPa) 500 UBC SCPM 3/4/87 HOULSBY UNLOADING CYL Armada Pile Stte—Depth=10.9m 400 4 /->» o ft 3 m ? Q. O o 300 H 200 4 100 4 -In(E0 - E) E»Natural Strain UBC SCPM 3/4/87 REPLOT 26/10/87 ANNACIS PILE D=»12.4 M 600 -T -100 H 1 1 1 1 1 —l r——i——I 1 r T" 0 4 8 12 16 20 24 Infinitesimal Strain % UNCOR + COR UBC SCPM 3/4/87 REPLOT 26/10/87 ANNACIS PILE D«12.4 m 2 Z o § u Q 0.5 0.4 4 0.3 0.2 4 0.1 4 0.0 -0.1 • ARM1 200 COR PRESSURE (KpA) + ARM2 • ARM3 au OJ OS CP ^8Z UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile - Inf Depth : 12.4 m Date : 3/4/87 1 10 102 LOG CURRENT VOLUMETRIC STRAIN UBC Seismic Cone Pressuremeter—3/4/87 Annacla Pile Sfte-Depth=12.4m Average Strain (%) Natural Strain 500 400 H o CL O L. 3 S) n CL 300 200 -i 100 4 UBC SCPM 3/4/87 HOULSBY UNLOADING CYL ANNACIS PILE D=12.4 U 5u- 3-lQ kfo 5* • left qpk CO 2 -r 4 6 8 10 -ln(E0 - E) E=Notural Strain Inftnlteatlmal Strafn ( % ) UNCOR 4- COR UBC SCPM 3/4/87 REPLOT 17/12/87 ANNACIS PILE D=14.0 M to 0^ 0 200 400 • arm1 CORRECTED PRESSURE ( kPa ) + drm2 • arm3 UBC Seismic Cone Pressuremeter-3/4/87 Annacis Pile Stte-Depth«= 14.0m CO +-4- PM Average Strain (%) Natural S+rain« UBC SEISMIC CONE PRESSUREMETER % Site : Annacis Pile - Inf Depth : 14.0 m Date : 3/4/87 500-j 1 1—i—i—i i i i | -j 1—i—i—i tiii LOG CURRENT VOLUMETRIC STRAIN % UBC SCPM 3/4/87 HOULSBY UNLOADING CYL Annaci8 Pile D=14.0 m 50 4 0 H 1 r~ 1 1 1 1 1 1 1 1 0 2 4 6 8 10 -ln(E0 - E) E=Natural Strain Site Date Pressuremeter On Site Location Comments Lulu Is - UBCPRS 8/1/88 UBC SCP JAN8 Strain Controlled Test Depth Strain Rate Approx. Relaxation ( m ) ( %/min ) Period ( min ) 4.75 14.7 7.5 7.75 13.4 9.7 10.75 12.9 13 13.75 12.9 7.2 Cavity Strain [%] Avg. of arms 1-2—3 SCPM 8/1/88 Annacfs Pile D=4.75 m 1 0.5 • Arm #1 . Arm Deflection [mm] + Arm #2 <• Arm #3 ^93 UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile 300 250 H D Q_ LU m §200 LU cr: CL o r- 150 H 100 Depth : 4.75 m Date : 8/1/88 i i i i i i in 1 1—l—II iir 5a= 172-loo , 3/.5kft 2.303 + + ,+++++ + T I I I llll| -1 1 1 1 | | | | 10 108 LOG CURRENT VOLUMETRIC STRAIN % SCPM 8/1/88 Houlsby Unloading Cyl Annacis Pile D=4.75 m -j , 1_, , , , , j j j j j 0 2 4 6 8 10 -ln(E0 - E) E=Natural Strain 200 SCPM 8/1/88 Annacis Pile D=7.75 m J 0.5 • Arm #1 Arm Deflection [mm] + Arm #2 • Arm #3 296 UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile Depth : 7.75 m Date : 8/1/88 Seismic Cone Pressuremeter 8/1 /88 Annacis Pile D=7.75 m 5 7 9 11 13 15 Cavity Strain [%] Avg. of arms 1 -2-3 scrM a/i/oo Houlsby UNioading uyi Annacis Pile D=7.75 m 0 2 4 6 8 -ln(E0 - E) E=Natural Strain Seismic Cone Pressuremeter 8/1/88 Annacis Pile D= 10.75 m i—i—i—i—i—T—i—i—i—i—i—i—i—i—i—i—r 3 5 7 9 11 13 15 17 19 Cavity Strain [%] — Avg. of arms 1-2-3 o CL © L. 3 a n £ Q. 260 240 -220 -200 180 160 140 120 -100 -80 -60 40 -20 -0 -20 -0.1 • Arm #1 SCPM 8/1/88 Annacis Pile D= 10.75 m r~ 0.1 0.3 Arm Deflection [mm] + Arm #2 o Arm #3 3oi UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile Depth : 10.75 m Date : 8/1/88 SCPM 8/1/88 Houlsby Unloading Cyl Annacis Pile D= 10.75 m 400 -i ~ln(E0 - E) E=Natural Strain Seismic Cone Pressuremeter 8/1/88 Annocl8 Pile D=13.75 m 1 1 r—i i i 1 1 j 1 1 j , , , r 3 7 9 11 13 15 Cavity Strain \%] Avg. of arms 1 -2-3 SCPM 8/1/88 • Arm #1 Arm Deflection [mm] + Arm #2 O Arm #3 UBC SEISMIC CONE PRESSUREMETER Site : Annacis Pile Depth : 13.75 m Date : 8/1/88 LOG CURRENT VOLUMETRIC STRAIN s Corrected Pressure [kPa] Site : Lulu Is - UBCPRS Date  11/2/87 Pressuremeter : Hughes SBPM On Site Location : FEB11 Comments : Quasi-Strain Controlled Test Strain range is the range in cavity strain over which the strain rate has been calculated. Depth Strain Rate Strain Range Approx. Relaxation ( m ) ( %/min ) ( % ) Period ( min ) 4.8 4.3 0-9.5 1-5 6.35 8.1 0-16 1-5 7.9 8.5 0-16.9 1-5 9.4 6.4 0-13.3 1-5 10.9 8.0 0-16.4 1-5 12.4 2.6 0-16.4 1-5 0 Q. X £ 3 n m © Q-"O O +> o £ L. 0 o 10 0 Self-Boring Pressuremeter-11/2/87 UJ«* I* - U8CPRS-Depth:4.8m FtbU.Ocfl •1 &ur * 0.7Z MPa • A** 3.3% .3V. Arnold StW = Zl.3kP<i | ModtW Arnold Su^ - Hi kPa 50 40 30 20 -ffi <3 •, •= O.fMPa a - io2.* VJ& 0 0 0—— T" 4 T" 6 8 "1 10 12 • Measured + Average Strain (%) Arnold "fype-l Stress-Strain Na+ur-al 6-V Curve Ft+ 0 CD Self-Boring Pressuremeter-11/2/87 Lulu, 35-U6CPfS-Depth:4.8m 120 160 200 240 Pressure (kPc) — Arm 2 Arm 3 3l o SELF - BORING PRESSUREMETER Site : Lulu Is-UBCPRS Depth ; 4.8 m Date : 11/2/87 1 10 10* LOG CURRENT VOLUMETRIC STRAIN Self-Boring Pressuremeter—1 LUIIA Hi-UBCpR5-.Depth:6.35m /2/87 Fcbll.oo3 Arnold Su^- 23.0 kPa ModrrVa A^old 5u^K = 24.4 kPa. 6t- 1.1 MPa W 05 A 0 0 o o 0 7 p r j r 6 8 10 12 T 1 -14 "7—r 16 18 Measured Average Strain (%) Arnold Ttjpe. V <> Stress-Strain Self-Boring Pressuremeter- i i/^/"' LuAu Is - U&CPKS-Depth:6.35m lur-0.62Hfa Arm 1 "120 160 Pressure (kPa) Arm 2 Arm 3 SELF - BORING PRESSUREMETER Site : Lulu Is-U8CPR5> Depth : 6.35 m Date : 11/2/87 LOG CURRENT VOLUMETRIC STRAIN Self-Boring Pressuremeter-11 /2/87 Lulu I*.-uecpRS -Depth:7.9m 1,004 0 2 4 6 8 10 12 14 16 18 20 Average Strain (%) C Measured + Arnold Type 1 O Stress-Strain Cu»*ve FIT 3 a o © CM a a 4-SBPM 11/2/87 ARNOLD TYPE 1 lulul3-UBCPR5D=7.9m SUavg=23.4 em«=10 Natural Strata % Strain 2\Tr SELF - BORING PRESSUREMETER Site : Lulu Ts- UBCPRS Depth : 7.9 m Date : 11/2/87 SBPM 11/2/87 Houlsby Unloading Cyl La\ul6-U8CPR5 -Depth:7.9m 1 1 1 1 1 1 1 1 1 1 1 0 2 4 6 8 10 ~ln(E0 - E) E=Natural Strain o n 2 0) n £ Q. 300 280 -260 -240 -220 -200 -180 -160 -140 120 -100 -80 60 40 20 --o Self-Boring Pressuremeter-11 /2/87 febli.ooS Uiu Ts- UBCPRS -Depth:9.4m I54 T 1 1 1 1 r 4 6 8 ~i r 10 12 T r-14 Measured Average Strain (%) (Mature, l) + Corrected o CL X © n m © t_ D. •u <D +-> O © 0 o 260 240 -220 -200 180 H 160 140 120 -100 -80 60 40 20 H Self-Boring Pressuremeter-11 /2/87 UIUJA- UBCPRS -Depth:9.4m I64" tnf ja^orx dz-l83 1.9? b« .OMZ-33 6u- W Hfe Arnold Siw * 22 kPa ModiW 5IA^X - Z3.I kPa Thi* (t> a lovv Su.J fo55iblu 3 S^eMr cksfu.r\)eA 4^5f «' 2 4 - Measured T 6 8 10 12 -r-14 Average Strain (%) ( Natural) + Arnold Type I Curve. FIT Self-Boring Pressuremeter-11 /2/87 0 40 80 120 160 200 240 280 Arm 1 Pressure (kPa) Arm 2 Arm 3 SELF - BORING PRESSUREMETER Site : Lalu Is- U6CPRS Depth : 9.4 m Dote ; 11 /2/87 Corrected Pressure (kPa) Self-Boring P.M., 11/2/87 Lulu I5- OBCPRS -Depth:10.9m FtB U-OOfi Average Strcfn (%) (KJaKxral — - Co rr. Press. (kPa) Self-Boring Pressuremeter-11/2/878 Lulu Ts - U8CPR5 -Depth: 10.9m ro 250 240 -230 -220 -210 -0 Q. 200 190 _ 0 i_ 180 essi 170 — Cor Pr 160 150 — i 140 130 -120 -110 -100 SBPM 11/2/87 ARNOLD TYPE 1 LuluXs.UBCPR5D=10.9 m SUmax=24.3 kPA + + + Arwold Sawv^^ 24.3 kPa Modrpfed A*>o The. SM. ob+ai^cl Is |otO. 5ome, disWbance way Uavc occurred. AUo p^lonaexJl pttn'cdj of" Creep before JtW w/r (°0p*-do KO+ KVTSIPC- 4WS -res)-- VRKJ 5cLikbW. -for C^CLLISTIUI^ 5tt-; ~r 2 6 8 I 10 12 14 16 18 Natural Strain % Data Points VP (T SBPM 11/2/87 ARNOLD TYPE 1 LuKuftlPRS D=10.9 m SUavg=19.7 kPa em=10 Natural Strain % Strain 328 SELF - BORING PRESSUREMETER Site : LJIU Is-UBCPRS Depth : 10.9 m Dote : 11/2/87 1 10 10* LOG CURRENT VOLUMETRIC STRAIN 500 400 -4 300 200 "4 100 -j Self-Boring P.M., 11/2/87 Lulu lb.-UBCPR5 -Depth: 12.4m febll.OO^ Corr. Pressure kPa H 18 Average Strain (%) (NJaWaf) 22 C 20 19 18 17 16 15 H 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Self-Boring Pressuremeter-11 /2/87 Lulu 36.-UBCPRS -Depth:12.4m Po = 255 K?3 This Po -i3 considerable hfcjW 4han +V\c Po calculated TTO'VA ploh of -Hit co/vee-fed pressure, vs average plof on "Hoc ' previous pagc.Tl'ii*. oonjd otcW +o stale af u/U f court (* puffed, A UPM£ Po Jf 23o is Ta^cio TO be Corvttk 0 200 400 Arm 1 Pressure (kPa) Arm 2 Arm 3 o Q. o l_ ZJ n m v Q. i_ 0 O 360 350 340 330 320 310 300 290 280 270 260 250 240 230 220 -1 SBPM 11/2/87 ARNOLD TYPE 1 ANNACIS D=12.4 m SUmax=32.1 kPA MfltltfW Arnold * 3 2.1 fcPa. Th& "6u is low. Some Dr-s-K^kance-1 o-p creep mr| vwakd. 4U15 £3 3 11 13 15 17 Natural Strain % Data Points 0» V>3 Natural Strain % Strain 3^3 SELF - BORING PRESSUREMETER Site : UUIs-OBcPRS Depth : 12.4 m Date : 11/2/87 T i i i i i i | 1 1—~i—I I I I I I i i i i i i i i | 1 1 1—i i i i i 1 1 10 102 LOG CURRENT VOLUMETRIC STRAIN 33 <4 Site : Lulu Is - UBCPRS Date  19/2/87 Pressuremeter : Hughes SBPM On Site Location : FEB19 Comments : Quasi- Strain Controlled Test Strain range is the range in cavity strainover which the strain rate has been calculated. Depth Strain Rate Strain Range Approx. Relaxation ( m ) ( %/min ) ( % ) Period ( 4.9 4.3 0-18.5 1-5 6.3 2.8 0-3.5 1-5 7.9 9.5 0-19.2 32 9.4 6.4 0-13.3 1-5 10.7 4.2 0-12 1-5 12.5 2.1 0-17.4 1-5 14.0 2.5 0-17.4 1-5 260 SBPM 19/2/87 REPLOT 28/10/87 lukxXs,- UBCPRS -Depth:4.9m TeB\9.0tfL o 0. m m © Q. •o 9 IS I O O 20 Average Strain (%) — Cavi+w strain Self-Boring Pressuremeter-19/02/87 Lulu l3.~U8CPGS-Depth:4.9m.SBPM#3 — Arm 1 "pry^ r 120 160 200 Pressure (kPo) Arm 2 Arm 3 240 o CM E <5 o O Q O CM CM O CM O O CM O O) O 00 O o CO o lO o SBPM 19/2/87 ARNOLD TYPE 1 D=43 m SUavg=17.9kPa em=10 Cavjiti^ Strain % • Strain SELF - BORING PRESSUREMETER Site : Lulu X5-UBCPRS Depth : 4.9 m Date : 19/2/87 o Q. 3 to 0) "8 -f-> o © b o o SBPM 19/2/87 REPLOT 29/10/87 Lulu. Tjs.- 06CPR5 -Depth:6.3m 0. -Cawrtij Strain 8 10 12 Average Strain (%) 3*1 ' T SBPM 19/2/87 ARNOLD TYPE 1 blu ID-UBCPRS D=6.3M SUmax=20.0 kPa v a. 3 « m CL "O 9 +» o P. 0 o C^avi+ij Data Points Strafn X SBPM 19/2/87 ARNOLD TYPE 1 T I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3 5 7 9 11 13 15 17 19 21 CavHHj Strain % Strain 344 SELF - BORING PRESSUREMETER Site : LoUX^- UBCPRS Depth : 6.3 m Date : 19/2/87 200 H o Lul or z> 00 CO Ld 150 OL o r-100 T 1—I I I I 1 11 —I 1—I I I ITT] 1 1—nTTTTT 5u.~ r7B,6-t54 10 1 1—I TTTTTp ' ' I 1—I I I I M | -1 1 10 —r—i—i IIIII 10* LOG CURRENT VOLUMETRIC STRAIN 34 5" Self — Boring Pressuremeter—TS/ 7 26 24 LuW Ts - UBCPRS -Depth:7.9m "1 D •*-> 22 20 18 16 14 12 10 8 6 4 2 0 P.*l3H 134+ 14?* 143Kfe 100 Arm 1 200 Pressure (kPa) Arm 2 Arm 3 300 400 SELF - BORING PRESSUREMETER Site : Lukls-UJ&PRS Depth ; m Date : 19/2/87 ouu- I I I I 1 l I 1 [ i i J y I i TT" 8. / \ PRESSURE ro O t i i I i /?\1 " J < 200-£ ; II 150- 2303 ^ 45A IcPa 100 --1 WW i i 1 I 1 1 1 I | • i i i J i i r 1 10 10 LOG CURRENT VOLUMETRIC STRAIN SeIf~3or!ng Pressuremeter-19/02/87 Lulu Is-UBCFRs ~Depth:7.9m(repeat) 5fc-iYrfl&koM R-b |$.005" T~T~"~T—r 4 6 ~r 8 10 12 14 16 -T" 18 20 Average Strcfn (J5) c 2 OT 20 19 — 18 17 -16 -15 14 13 12 -11 -10 -9 ... 8 -6 -5 4 -3 -2 -1 -0 0 Self-Boring Pressuremeter-19/02/87 Lulu Is- UBCPRS~Depth:7.9m(repect) £e_ ,v,ftah Arm 1 Pressure (kPa) Arm 2 • Arm 3 —I— 280 Self-Boring Pressuremeter— 19/2/87 Lota Is- ~Depth:9.4 m Feb 19-006 Average Strain {%) (^MaKtral SBPM 19/2/87 ARNOLD TYPE 1 Lulu Is-UBCH^ D=9.4m SUavg=32.2kPa em=10 % i r 1 1 1 1 1 r—i 1 T 3 5 7 9 11 Natural Strain % Strain 20 — 19 -18 i 17 -j 16 -j 15 4 u —| 13 H 12 4 11 -j 10 -4 9 4 8 H i ' ^ 6 4 5 4 4 4 3 4 ! 2 -1 1 I o 4 Self-Boring Pressuremeter-19/2/87 Lulu Is - UBCPRS -Depth:9.4 m // / / f / //^7 / ft / •?/ // /./ 100 ' 200 3 - Mo ttk _ 300 j 400 — Arm 1 Pressure (kPa) Arm 2 Arm 3 SELF - BORING PRESSUREMETER : bk Is- UBCPR5 Depth : 9.4 rn Date : 19/2/87 Self-Boring Pressuremeter-19/2/87 Average Strain (%) (rOaW&l^ . Self Boring Pressuremeter— 19/2/87 Lola Hs-UBCFfcS ~-Dopth:10.7 m 3 / f.= I4S |cp8 // / / / S^ZJhf I / '7 40 80 ~ Arm 1 120 160 200 Pressure (kPa) 240 - Arm 2 Average Strain (%) Self-Boring Pressuremeter-19/2/87 Ulul6-u8CP£S-Depth:12.5 m 600 -r — 500 -1 I I I 1 r—I—l—I—1 1 1 1 1 1 1 1 j 1 1 0 2 4 6 8 10 12 14 18 18 20 Average Strain (%) C NaWaIs) Strain («) 0-»M(d^WOIMffl(00-'MOl^OlO)M01fflO 500 400 -» 4> 300 -200 -100 -Self-Boring Pressuremeter-19/2/87 UI u. Js - 06C PRS -Depth:!4.0 m Correced Pressure Average Strain (%) ( Ma+uraf) +• Arnold SBPM 19/2/87 ARNOLD TYPE UUts-u&CPKS. D= 14.0m SUavg=41.4 kPa em=10 ^ j r---i j 1 1 --1 r~ 4.6 8 10 12 Natural Strain % Strain Self-Boring Pressuremeter-19/2/87 Lok Xs -OBCPRS -Depth: 14.0 m Pressure (kPa) Arm 2 Arm 3 SELF - BORING PRESSUREMETER Site : Lu\u IS-(JB£PR5 Depth : 14.0 m Date : 19/2/87 • 500 -i T 1—i J- IT rri 1 r —1ITTTT] 1 10 10* LOG CURRENT VOLUMETRIC STRAIN % 3^3 APPENDIX III PRESSUREMETER TEST DATA AT LANGLEY LOWER 232 36n Site : Langley Lower 232 Date  10/12/87 Pressuremeter : UBC SCP On Site Location : DEC10 Comments : Strain Controlled Test Depth Strain Rate Approx. Relaxation ( m ) ( %/min ) Period ( min ) 1.0 11.5 >20 2.0 8.3 >23.0 12.6 18 5.0 12.2 8.3 7.0 12.3 9.6 9.0 12.3 7.0 11.0 12.1 10.3 13.0 12.0 8.0 14.1 10.2 >316.0 11.4 >30 SCPM 10/12/87 Langley Lower 232 D=1.0 m 350 i • — Cavity Strain ( % ) SCPM 10/12/87 Langley Lower 232 D=1.0 m -0.1 0 0.1 Arm Deflection [mm] • Arm #1 + Arm #2 O Arm #3 UBC SEISMIC CONE PRESSUREMETER Site : Langley Lower 232 Depth : 1.0 m Date : 10/12/87 LOG CURRENT VOLUMETRIC STRAIN s SCPM 10/12/87 Lower Langley 232 Houlsby Unloading Cylindrical D=1.0 m 0 2 4 6 8 10 -ln(E0 - E) E=Natural Strain SCPM 10/12/87 Langley Lower 232 D=2.0 m 200 -i r 190 -Cavity Strain [%] Avg. of arms 1—2—3 SCPM 10/12/87 • Arm #1 Arm Deflection [mm] + Arm #2 O Arm #3 3*1 UBC SEISMIC CONE PRESSUREMETER Site : Langley Lower 232 Depth : 2.0 m Date : 10/12/87 1 ~r r-T—r-rr-n r r~-r—r-T-rTT 1 1 10 102 LOG CURRENT VOLUMETRIC STRAIN % 0 a. x i—i I 3 O a I Q. © 0 © t 0 O SCPM 10/12/87 Lower Langley 232 Houlsby Unloading Cylindrical D=2.0 m "T 2 l.9l MPa -ln(EO ~ E) E=Natural Strain UBC SCPM 10/12/87 HOULSBY UNLOADING CYL Langley Low 232 D=2.0 m SU=16.6 kPa 120 -i 0 2 4 6 8 10 Natural Strain % Data Points UBC SCPM 10/12/87 Houlsby Unloading Cyl Langley Low232 D=2.0 m Natural Strain % Strain SCPM 10/12/87 Langley Lower 232 D=3.0 m 300 1 : 280 -I 260 -240 -Cavfty Strain [X] Avg. of arms 1-2-3 • Arm #1 Arm Deflection [mm] + Arm #2 O Arm #3 I—I o 0. X I I £ 0) 0) o D. •D 0 +> o £ L. 0 o 260 240 -220 -200 -180 -160 -140 -120 -100 80 -60 40 -20 -0 SCPM- 10/12/87 Lower Langley 232 Houlsby Unloading Cylindrical D=3.0 m 8 + 10 -ln(E0 - E) E=Natural Strain + EO = .1716 SCPM 10/12/87 Lower Langley 232 ~ln(E0 - E) E=Natural Strain + EO = .174 Cavity Strain [%] Avg. of arms 1-2-3 SCPM 10/12/87 Langley Lower 232 D=5.0 m 260 -i j :  -0.1 0.1 0.3 Arm Deflection [mm] • Arm #1 + Arm #2 O Arm #3 3© i UBC SEISMIC CONE PRESSUREMETER Site : Langley Lower 232 Depth : 5.0 m Date : 10/12/87 350 -i 1 1—i—i i i i i i 1 1—i—> i i i i i LOG CURRENT VOLUMETRIC STRAIN * SCPM 10/12/87 Langley Lower 232 Houlsby Unloading Cylindrical D-5.0 m »ln(E0 - E) E=Natural Strain 0 n PI © © o © 0 o UBC SCPM 10/12/87 HOULSBY UNLOADING CYL Langley Low 232 D=5,0 m SU=21.3 kPa "Hviptrl?olcc Curve frr CP 8 10 Natural Strain % Data Points UBC SCPM 10/12/87 Houlsby Unloading Cyi Langley Low232 D«5.0 m Natural Strain % Strain 400 350 300 J 250 -\ 200 150 -i 100 50 -I SCPM 10/12/87 Langley Lower 232 D=7.0 m o 4 Arm 1 3 Arm Deflection [mm] Arm #2 ~ Arm #3 400 SCPM 10/12/87 Lower Langley 232 D=7.0 m 350 -o Q. £ 3 n 0) £ D_ © o £ 0 o 300 -250 -200 -150 J 100 -CO 50 -_l—n , , , 1 1 1 1 1 1 1 i i r i i r~ 2 4 6 8 10 12 14 16 18 20 Cavity Strain [%] Avg. of arms 1-2—3 Pressure [kPa] > -i 3 ho o o 5* •1 i i > i 04 36© UBC SEISMIC CONE PRESSUREMETER Site : Langley Lower 232 Depth : 7.0 m Date : 10/12/87 1 10 10* LOG CURRENT VOLUMETRIC STRAIN x 0 Q. 2 3 n 0) e Q. •o © o 2 i_ o o 350 300 -\ 250 -4 200 -4 150 -4 100 -4 50 ~\ SCPM 10/12/87 Lower Langley 232 Houlsby Unloading Cylindrical D=7.0 m +++ 6/^-87 8 -ln(E0 - E) E=NaturaI Strain + E0 = .1596 SCPM 10/12/87 Lower Langiey 232 Houlsby Unloading Cylindrical D=7.0 m + + + + I— -ln(E0 - E) E=Natural Strain EO = .162 SCPM 10/12/87 Lower Langley 232 Houlsby Unloading Cylindrical D-7.0 m -ln(E0 -- E) E=Natural Strain + EO = .164 UBC SCPM 10/12/87 HOULSBY UNLOADING CYL Langley Low 232 D=7.0 m SU=22.0 kPa 150 -i _____ ... 0 2 4 6 8 Natural Strain % Data Points /-s O Q. I UBC SCPM 10/12/87 Houteby Unloading Cyl Langley Low232 D=7.0 m Natural Strain % Strain SCPM 10/12/87 400 350 H Langley Lower 232 D=9.0 m 300 250 ~\ 200 -\ 150 H 100 -\ 50 -i* Cavity Strain [%] Avg. of arms 1-2-3 SCPM 10/12/87 • Arm #1 Arm Deflection [mm] + Arm #2 O Arm #3 334 UBC SEISMIC CONE PRESSUREMETER Site : Langley Lower 232 Depth : 9.0 m Date : 10/12/87 400 -j- r 1—i—i IIIII i 1—i—i i i/i r 350 -A o CL lxl Dd tf> 300 CO 1x1 on a. 250 200 5.i~3oa.4- loo 1 r—i—i i i i i' LOG CURRENT VOLUMETRIC STRAIN * 10 1 0 Q. i i c _ 9) n c Q. © © b o o 400 350 H 300 H 250 200 150 100 -f SCPM 10/12/87 Lower Langley 232 Houlsby Unloading Cylindrical 0=9.0 m 50 H + + -ln(E0 - E) E=Natural Strain EO = .1642 8 o Q. X _ 3 0) V) £ CL •o 0 +» o _ O o 400 350 H 300 -4 250 -i 200 -\ 150 -4 100 -4 50 SCPM 10/12/87 Lower Langley 232 Houlsby Unloading Cylindrical D=9.0 m + + CP 8 -In(E0 - E) E=Ncrtural Strain 4- E0 = .164 UBC SCPM 10/12/87 HOULSBY UNLOADING CYL Langley Low 232 D=9.0 m SU=21.0 kPa 1 1 1 1 1 1 1 1 1 1 1 0 2 4 6 8 10 Natural Strain % Data Points UBC SCPM 10/12/87 Houlsby Unloading Cyl Langley Low232 D=9.0 m 26 —J : __ 0 2 4 6 8 10 Natural Strain % Strain Cavity Strain [%] Avg. of arms 1-2-3 SCPM 10/12/87 Langley Lower 232 D=11.0 m ' n ~1 1 1 1 1 1 1 1 1 r -0.1 0.1 0.3 0.5 0.7 0.9 Arm Deflection [mm] • Arm #1 + Arm #2 • Arm #3 UBC SEISMIC CONE PRESSUREMETER Site : Langley Lower 232 Depth : 11.0 m Date : 10/12/87 LOG CURRENT VOLUMETRIC STRAIN % o Q. a a 9 •o 9 +> o I v_ O O 400 350 -\ 300 H 250 -4 200 -4 150 4 100 4 50 4 SCPM 10/12/87 Lower Langley 232 Houlsby Unloading Cylindrical D=11.0 m + + + 2 T" 4 -ln(E0 - E) E=Notural Strain 6 8 UBC SCPM 10/12/87 HOULSBY UNLOADING CYL Longley Low 232 D-f1.0 m SU=23.4 kPa Natural Strain % Data Points Natural Strain % Strain 500 SCPM 10/12/87 Langley Lower 232 D=13.0 m 400 -4 o a. © L. 3 0) n _ Q. •o © O I 0 o 300 -4 200 H 100 -4 Cavity Strain [%] Avg. of arms 1-2-3 SCPM 10/12/87 Langley Lower 232 D=13.0 m 450 - 1 ~0.1 0.1 0.3 Arm Deflection [mm] O Arm #1 + Arm #2 • Arm #3 Ao<=\ UBC SEISMIC CONE PRESSUREMETER Site : Langley Lower 232 Depth : 13.0 m Date : 10/12/87 0 D_ X 3 0) 0) c Q. •o 0 L. 0 o 500 400 -\ 300 ^ 200 H SCPM 10/12/87 Houlsby Unloading Cyl Langley Lower 232 D=13.0 m + + - 3.3 8 HPa. o 100 H 4-T 4 6 8 10 -lnn(E0 - E) E=Natural Strain o 0_ X £ n n £ Q. •o <D +> 0 £ _. o o 200 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 UBC SCPM 10/12/87 HOULSBY UNLOADING CYL Langley Low 232 D=13.0 m SU=25.6 kPa Crr UftlracUtAj 'Curve 4-4 ~T~ 6 T 8 10 Natural Strain % Data Points UBC SCPM 10/12/87 Houlsby Unloading Cyl Langley Low232 D=13.0 m Natural Strain % Strain 700 SCPM 10/12/87 Langley Lower 232 D=14.1 m 600 0 + -1 Pressure [kPa] Cavity Strain [%] Avg. of arms 1 —2—3 500 400 H !p0-&9- left o Q. £ m n £ Q. 300 -i 200 -4 100 -i -0.1 SCPM 10/12/87 Langley Lower 232 D=16.0 m 0.1 0.3 0.5 Arm Deflection [mm] Arm #2 O Arm #3 UBC SEISMIC CONE PRESSUREMETER Site : Langley Lower 232 Depth : 16.0 m Date : 10/12/87 1 10 10* LOG CURRENT VOLUMETRIC STRAIN % Corrected Pressure [kPa] A\9-APPENDIX IV  DERIVATION OF UNLOAD RELOAD SHEAR MODULUS DE-RWATiON Op EQUATION FoR 6ur In chapW 'Tour m ec^. A.-Y) fs vie a — ^ (Sur= APT i-i-sOi -fhe d.er(\/a4fovi is as 4ollov/us : CCovi^icler -file, expansion °r wlvacdiow o*f a o^i^cWfcal C-ui-Vtj in IjiAeav C^35T(C 9 Viowio^t^eoas 3nd \5oWop\c rviedi.ui/n. Stress e 5 3,4 Ec^AiUb Poydiv/e, c©/vn press statuses a^d ctj(i/dvica\ of spta«nca\ ^ip-dmaTes £ l'S&->:0 are, used . For strnsll dd-forwad Cons 3»od culin drfCol cavi-ta^ exp&wsicm 4ke ^OIIOU^VKJ 6^u.a-rio/\ results • . OV -6e _ O A4. I 5+ ram's The, Caujcla^ cU-f ivnvliov^ 0-f 5-Vram i*5 Ul^ed . Bon^axion 1-5 pos-t-h'v/e. '_Kvd -ovyj-racTiovo vnegs4we. TV»e ec|a_rVioms -TDV radial avA "tar^cnTial -5-Vra'm as -follows *. U+ du -dr —AX- A.. . £r - 22 =- ___ A 4.2, dr dr These. e^uaTior\s spp]u ov\lu JXJV ^mall 5rramsand >u. de notes 4W <d»'5p)ace^v\€^-T a-f radiums r. Cpi^5-TiTiAT\\ye Elgi^a-hon, As/Su^imc^ a Co\r\d'\\'\o\a of radial p\awe $4rai^-,4Ue princi pal 6-WaiV\ direc4coiAS are radial 0 Ta\/^e»/vria.I and wai . £r - ± far - »Ad&-JJ Ad^) " Ee - x^AcTe - i>&6r -2>k6^) A 4.5 = (l-i^r-^O + ^fr A 4.8 E£*~ 0-^L\<5* -J>(aA4.9-SubsTiTurceaualfo^s A4.2 3IACJ, A4.3 in eou3T-foMs A4.0 AM.9 'one OWB.^S : 5uiWli-U.-\-(n^ An.10 B^d A4.U iMo A4.1 re^l-fe i/i r"2 diLL t- YCLL - - o A4.IZ Soly/iiA^ -\-Ue_ Lmeay ELVa^Tfc Problem 5oUin^ fo<- 4lrte ca^e o*f a cult/id/real cav/"4-uj wi-rU \»oi4ral radium fo 4^>e. general UXlOVl |<> The. tau^lav^ co\nA\\\ov\<> srl- 4"Ue U/3II o£ 4W cavf-kj 3rd. 6V-P fo-.^/f,, •awd ck^ <5& . TVweW fX equals O . 42/2L A4 4he wall crF 4W Cauda = rG 4 Ue re-fore. 8 = >Ooro= To"1. 3 C^O/nb^ina e-_.u.a-f<"oins A4-Z au\d A^-IO Ovid A4-II O^. £e -4-v»decrial -5"W<9ivi _4 4Vie. 6 - 4civvdjevi-lial s4v<_fn r _ cv - Po -f £_c_v Po + Ack AT 4W vvjall of 4V\e cayrV^ r*2-- Vo7- _^d. £& - W°/r_ p = p0 -t 2<_^ A4(8 for 3 pre^5u.r-ery\eT-er unload / reload \t$\ T^e radius Q4 fWe. CBvi-ru^ VAJBW f>W>v*m \wv ecj. A4.18 *5 KVO4 Psdvu.5 _rf ~f^e <Drtssuve welter in 4Ue. J-ullu defla.+ecl po5\Vioi/\# Ty^ead i4 dke radius <g-P 4-Ke, /vwddle <--r +W unload/ r&loadi loop. 42^ fuJIij (de-fU-red ^oe-'iTi'ov^ i-5 de-Pmed as 3o , The. 6ar - P-?c 257 A4.I5 11 Au "Sf Au0 _ 2L £ » - €«. 2. where, AP= Po-Po 6^ - (£. + £0/z "Hoe unload/^e[oadl 3 hear modulus can si so be oWaf U6i^ msTural S4VSM6 w<dv\ 4-W -fallowing ecjua-Won ' AP Ifeiflcj +He Mada^riVs Series W +W ina+ural sfraivi one. 42.4 l«0+*J4.")- &£p-~. Z 3 2. 3 4 * • * 4V\eiA e<\u£-l-iem r\4-22 3 iimpU-$ne£ +o AC* - £)-£i -42-5" APPENDIX V  SHEAR MODULUS VALUES SHEAR MODULUS FROM HOULSBY CYLINDRICAL UNLOADING ANALYSIS Site : McDonald Farm Date  27/1/87 Pressuremeter : UBC SCP On Site Location : JAN27 Comments : No piezocone or seismic measurements Strain controlled test Depth GH (Houlsby) GH/su REF 1r <Houlsby) ( m ) ( MPa ) 17.0 10.63 185.0 325 19.0 7.62 122.1 207 22.0 6.18 88.0 134 25.0 8.59 110.1 164 27.5 14.18 167.8 240 30.0 6.78 74.5 105 Site : McDonald Farm Date  7/11/85 Pressuremeter : FUGRO CP On Site Location : JAN27 Comments : No piezocone measurements Quasi-strain controlled test Depth GR (Houlsby) GH/SU REF Xr (Houlsby) ( m ) ( MPa ) 16.2 10.10 183.3 221 18.2 7.07 117.2 185 19.2 7.03 112.7 179 20.2 6.23 95.1 159 22.2 6.13 86.7 136 Site : Lulu Is - UBCPRS Date  3/4/87 Pressuremeter : UBC SCP On Site Location : APR3 Comments : Strain Controlled Test Depth GH (Houlsby) GH/su REF Ir (Houlsby) ( m ) ( MPa ) 3.0 2.40 60.4 122 4.0 1.58 52.0 83 4.8 1.58 61.5 109 6.35 2.36 88.4 165 ATI-7.9 3.72 126.1 197 9.4 2.91 90.1 146 10.9 5.50 155.8 209 12.4 3,85 79.1 104 14.0 3.89 79.9 148 Site Date Pressuremeter On Site Location Comments : : Lulu Is - UBCPRS 8/1/88 : UBC SCP : JAN8 Strain controlled test Depth GH (Houlsby) ( m ) ( MPa ) VSu REF Xr (Houlsby) 4.75 7.75 10.75 13.75 1.35 3.54 5.25 4.05 52.1 121 150.3 85.6 95 178 199 157 Site : Langley Lower 232 Date : 10/12/87 Pressuremeter : UBC SCP On Site Location : DEC10 Comments : Strain controlled Depth GH (Houlsby) GH/SU REF ( » ) ( MPa ) 2.0 1.91 72.1 3.0 2.36 102.6 5.0 2.25 118.4 7.0 2.14 115.7 9.0 2.01 98.0 11.0 2.36 ' 96.3 13.0 3.38 112.7 16.0 4.59 Ir (Houlsby) 90 142 121 87 92 101 117 131 UNLOAD RELOAD SHEAR MODULUS Site : McDonald Farm Date  27/1/87 Pressuremeter : UBC SCP On Site Location : JAN27 Comments : No piezocone or seismic measurements Strain controlled test Depth Gur Cavity Strain Time Wait Gur/Su REF ( m ) ( MPa ) Increment (%) ( sec ) 22 5.58 .97 79.5 22 9.03 .57 128.6 25 6.96 1.02 89.2 25 9.72 .69 124.6 27.5 6.98 .81 82.6 27.5 8.19 1.14 96.9 27.5 16.9 .34 1040 200 30 7.19 .79 79 30 8.96 1.03 98.5 Site : McDonald Farm Date  7/11/85 Pressuremeter : FUGRO CP On Site Location : NOV7 Comments : Unload reload loops are very small and poor quality Quasi-strain controlled test Depth Gur Cavity Strain Time Wait Gur/Su REF ( m ) ( MPa ) Increment (%) ( sec ) 16.2 13.4 .40 200 243. 2 16.2 35.7 .072 200 647. 9 16.2 21.7 .22 300 393. 8 18.2 7.84 .58 380 130 18.2 9.72 .40 230 161. 2 Site Date Pressuremeter On Site Location Comments : Lulu Is - UBCPRS 3/4/87 UBC SCP APR3 Strain controlled test Depth Gur Cavity Strain Time Wait Gur/Su REF ( m ) ( MPa ) Increment (%) ( sec ) 6.35 1.1 2.14 41.2 7.9 1.32 3.63 44.7 10.9 2.79 1.02 79.0 10.9 3.65 1.21 103.3 12.4 2.94 2.21 60.4 14.0 3.38 1.72 73.3 14.0 3.30 2.14 71.6 Site Lulu Is - UBCPRS Date : 11&19/2/87 Pressuremeter : Houghes SBPM On Site Location : FEB11 & FEB19 Comments : Quasi-strain controlled test Depth Gur Cavity Strain Time Wait Gur/Su REF ( m ) ( MPa ) Increment (%) ( sec ) 4.8 .72 3.49 28.0 6.35 .57 7.89 21.3 7.9 1.38 2.17 46.9 10.9 .91 5.72 125 25.8 10.9 1.6 3.0 125 45.3 12.4 1.37 4.91 200 28.1 6.3 1.1 5.04 315 43.1 7.9 2.5 1.06 84.7 9.4 1.62 4.17 50.2 10.7 .89 4.43 25.5 10.7 2.9 2.0 220 83.2 12.5 2.91 3.2 59.4 12.5 6.1 .91 150 124.5 14 6.5 .58 141.0 14 4.5 2.17 97.6 APPENDIX VI  IN SITU TEST LOCATIONS 224 J N GZAVBL General Area for UBC SCP tests srztL 3 B£FtUNl£ tox>T 2 1 General Area for-Fugro CP tests General Area for Hughes SBPM tests 8-I 4 M LEGEND • PIEZ0UZ7EJL COhlt T£6T m *AT WE: 0tLATOM£IBt. TEST fsiOTE '• ALL LPCATtoj? SITE PLAN OF McDONALD * s FARM m DIKE ROAD FRASER RIVER © © © © © 0 © VO MO MO VO I I -& 4 1300 1300 LEGEND i P/£ZOCOM£ TEST I I DMT-2 DKT-1 r UBC SCP-1J tIRl UBC SCP-2 4 LSCPT. -0 X-FVT-l l(Acc) •© •© •© SCALE 1 : 50 LULU IS.-UBCPRS SITE PLAN 43B> FVT-4 1 CPTU-3 -fr-FVT-5 A /-CPTU-4 -SCPT-1 (Acc)-1 UBC SCP-1 MoT TO MOTE. A_ Pi fcfcO CO »vJT£ 

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