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Energy measurements and correlations of the standard penetration test (SPT) and the becker penetration… Sy, Alexander 1993

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ENERGY MEASUREMENTS AN]) CORRELATIONS OFTHE STANDARD PENETRATION TEST (SPT) AN])THE BECKER PENETRATION TEST (BPT)byALEXANDER SYB.E., University of Queensland, 1975M.Eng., University of British Columbia, 1985A THESIS SUBMITTED IN PARTIAL FULFILMENT OFTHE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYinTHE FACULTY OF GRADUATE STUDIESCIVIL ENGINEERINGWe accept this thesis as conformingto the required standardTHE UNIVERSITY OF BRITISH COLUMBIAOctober 1993© Alexander Sy, 1993In presenting this thesis in partial fulfilment of the requirements for an advanced degree atthe University of British Columbia, I agree that the Library shall make it freely available forreference and study. I further agree that permission for extensive copying of this thesis forscholarly purposes may be granted by the head of my department or by his or herrepresentatives. It is understood that copying or publication of this thesis for financial gainshall not be allowed without my written permission.Department of Civil EngineeringThe University of British ColumbiaVancouver, CanadaDate 72 /293ABSTRACTThe Standard penetration test (SPT) and the Becker penetration test (BPT) are two of themost widely used in-situ tests in North America. The SPT is most commonly used in sandsand silty sands, while the BPT, being a large-scale penetration test, is more useful ingravelly soils. Both tests involve hammer impact on penetration rods, and the resultingpenetration resistance or blow count is strongly influenced by the amount of hammer energyactually transferred into the drill rods. To make use of the large world-wide foundationperformance data base currently available for the SPT, the BPT blow counts are commonlycorrelated to the SPT blow counts. Most of the existing correlations, however, have limitedapplications since they do not take into account the inherently variable output of the dieselhammer used in the Becker system and they ignore the soil friction acting on the Beckercasing during driving.This research shows that the existing methods of SPT and BPT energy calibrationshave serious shortcomings, and that a more fundamental approach of determining thetransferred energy, based on force and acceleration measurements, should be adopted forboth tests. The proposed approach provides a unified method of measuring transferredenergy in the SPT and BPT, similar in principle to that currently used in dynamic testing ofpiles.At four research sites in Greater Vancouver, SPTs, BPTs and electric conepenetration tests were conducted. Dynamic measurements were also carried out whichincluded force and acceleration near the top of the drill rods or pipes in the SPT and BPT,11ABSTRACT (continued)as well as bounce-chamber and combustion-chamber pressures in the double-acting dieselhammer during the BPT.An energy approach for correcting the measured BPT blow count to a referenceenergy level, similar in concept to that used for the SPT, is proposed. Factors affecting theBPT blow counts are investigated including hammer combustion conditions, different drillrigs, and different pipe sizes. The test results confirm that the measured transferred energyis a fundamental and useful parameter for normalizing the BPT blow counts to account forthe variable energy output of the diesel hammer.The effect of casing friction in the BPT is investigated by field measurements andnumerical analyses. New BPT-SPT correlations are proposed which consider the energytransfer in both tests and which, for the first time, account for casing friction in the BPT.It is shown that the proposed BPT-SPT correlations provide a rational framework fordetermining equivalent SPT N60 values from measured BPT blow counts, and can be appliedwith some confidence to gravel sites for which the BPT has proven to be a most practicaland economical testing technique.111TABLE OF CONTENTSABSTRACTTABLE OF CONTENTSLIST OF TABLESLIST OF FIGURESLIST OF SYMBOLSACKNOWLEDGEMENTS1. INTRODUCTION1.1 Origin of Standard Penetration1.2 Objectives1.3 Thesis Organization2. PREVIOUS INVESTIGATIONS2.1 SPT Energy Calibrations2.2 BPT Energy Considerationsiiivviiviii• . . . xiiixv16799192731383841495760Test and Becker Penetration2.3 BPT-SPT Correlations3. ENERGIES OF IMPACT PENETRATION TEST SYSTEMS4. DYNAMIC MEASUREMENTS AND ANALYSIS OF SPT4.1 Field Experiment at McDonald’s Farm4.2 Measured Stress Waves4.3 Wave Equation Analysis4.4 Results of Dynamic Measurements at McDonald’s Farm4.5 Significance of SPT Energy Correction FactorsTestivTABLE OF CONTENTS(continued)4.6 Limitations of SPT Energy Measurements 665. DYNAMIC MEASUREMENTS AND ANALYSIS OF BPT 695.1 Proposed Energy Approach for Normalizing BPT Blow Counts . . . 695.2 Dynamic Field Measurements 715.3 Measured Stress Waves 755.4 Variable Combustion Conditions 775.5 Different Drill Rigs or Hammer Conditions 815.6 Different Pipe Sizes 875.7 Summary and Recommendations for Energy Measurement of BPT . 936. BPT-SPT CORRELATIONS WITH CONSIDERATION OFCASING FRICTION 946.1 Experimental Test Sites 946.2 SPT and BPT Results 956.3 Effect of Casing Friction 1056.4 Proposed BPT-SPT Correlations 1117. VERIFICATION OF BPT-SPT CORRELATIONS 1168. RECOMMENDED PROCEDURE FOR ESTIMATINGEQUIVALENT SPT N 1239. SUMMARY AND CONCLUSIONS 1269.1 Summary of Research Study 1269.2 Dynamic Measurements of SPT 127VTABLE OF CONTENTS(continued)9.3 Dynamic Measurements of BPT 1279.4 BPT-SPT Correlations 1289.5 Recommendations for Future Research 129BIBLIOGRAPHY 131APPENDIX A ADDITIONAL SOIL INFORMATION AND TEST DATA .... 136APPENDIX B RESULTS OF CAPWAP ANALYSES OF BPT,ANNACIS TEST SITE 183viLIST OF TABLES2.1 Generalized SPT energy ratios (after Robertson et al. 1992) 194.1 Summary of SPT energy measurements at McDonald’s Farm 574.2 K1 and K2 correction factors and theoretical 2L’/c 615.1 Characteristics of BPTs at Richmond test site 756.1 Summary of CAPWAP resistances and measured BPT-SPT blow counts,Annacis test site 111viiLIST OF FIGURES1.1 Becker hammer drill system (from Harder and Seed, 1986) 52.1 SPT energy measurement concept using load cell (from ISSMFE, 1988) . . . 112.2 Idealized force-time waveform recorded by load cell in SPT drill rod 122.3 Different SPT hammers used in this study 182.4 Operating principle of double-acting atomized fuel injectiondiesel pile hammer (from Sy and Campanella, 1992a) 212.5 Energy chart for ICE Model 180 diesel hammer 242.6 BPT blow count correction chart based on bounce-chamber pressure(after Harder and Seed, 1986) 262.7 BPT-SPT correlations by Becker Drills (from Harder and Seed, 1986) 282.8 Correlation between corrected BPT blow count (Nba) and correctedSPT blow count (N60) (after Harder and Seed, 1986) 303.1 Methods of characterizing energy in pile driving 324.1 Cone penetration test data, McDonald’s Farm test site(after Sy and Campanella, 1991a) 394.2 SPT safety hammer used at McDonald’s Farm(from Sy and Campanella, 1991a) 404.3 Measured force, acceleration, velocity and energy traces for SPT blow 1at 1.5 m depth, McDonald’s Farm (after Sy and Campanella, 1991b) 424.4 Force, velocity and energies for SPT blow 1 at 1.5 m depth,McDonald’s Farm (after Sy and Campanella, 1991a) 44viiiLIST OF FIGURES(continued)4.5 Measured force, acceleration, velocity and energy traces for SPT blow 28at 9.1 m depth, McDonald’s Farm (after Sy and Campanella, 1991b) 464.6 Force, velocity and energies for SPT blow 28 at 9.1 m depth,McDonald’s Farm (after Sy and Campanella, 1991a) 474.7 Wave equation model for pile driving analysis 514.8 Measured and computed force and velocity traces for SPT blow 1 at1.5 m depth, McDonald’s Farm (after Sy and Campanella, 1991b) 544.9 Measured and computed force and velocity traces for SPT blow 28 at9.1 m depth, McDonald’s Farm (after Sy and Campanella, 1991b) 564.10 Calculated energy ratios and measured peak force vs depth,McDonald’s Farm 584.11 Energy ratios calculated by force integration method with and withoutcorrection factors, McDonald’s Farm 634.12 Comparison of SPT energy correction factors, 1(2, for effect of shortrod length (from Sy and Campanella, 1993a) 655.1 Bounce-chamber pressure (BCP), combustion-chamber pressure (CCP) andforce (FOR) time histories for three consecutive Becker hammer blows,including an expanded view of one blow at bottom(from Sy and Campanella, 1992b) 725.2 Cone penetration test data, Richmond test site(from Sy and Campanella, 1992b) 74ixLIST OF FIGURES(continued)5.3 Wave traces at 2.5 m and 10.0 m in BPT3, Richmond test site(from Sy and Campanella, 1992a) 765.4 Blow count (Nb), bounce-chamber (BC) pressure, peak force and ENTHRU vsdepth for BPT3 and BPT4, Richmond (from Sy and Campanella, 1992b) . . . 785.5 Bounce-chamber (BC) pressure and ENTHRU vs blow count (Nb) for BPT3and BPT4, Richmond (from Sy and Campanella, 1992b) 805.6 Measured (Nb) and corrected (Nba and Nb30) blow counts vs depth for BPT3and BPT4, Richmond (from Sy and Campanella, 1992b) 825.7 Blow count, bounce-chamber pressure, peak force and ENTHRU vs depth forBPT2 and BPT5, Richmond (from Sy and Campanella, 1992b) 835.8 Bounce-chamber pressure and ENTHRU vs blow count for BPT2 and BPT5,Richmond (from Sy and Campanella, 1992b) 855.9 Measured and corrected blow counts vs depth for BPT2 and BPT5, Richmond(from Sy and Campanella, 1992b) 865.10 Blow count, bounce-chamber pressure, peak force and ENTHRU vs depth forBPT3 and BPT5, Richmond (from Sy and Campanella, 1992b) 895.11 Measured and corrected blow counts vs depth for BPT3 and BPT5, Richmond(from Sy and Campanella, 1992b) 905.12 Corrected blow counts for BPT 3 vs BPT 5, Richmond(from Sy and Campanella, 1992b) 92xLIST OF FIGURES(continued)6.1 Corrected SPT (N60) and BPT (NbC and Nb30) blow counts vs depth,Richmond test site (from Sy and Campanella, 1993b) 966.2 Cone penetration test data, Annacis test site(from Sy and Campanella, 1993b) 976.3 SPT N60 data, Annacis test site (from Sy and Campanella, 1993b) 996.4 Blow count, bounce-chamber pressure, peak force and ENTHRU vs depth,Annacis test site (from Sy and Campanella, 1993b) 1006.5 Measured and corrected BPT blow counts vs depth, Annacis test site(from Sy and Campanella, 1993b) 1026.6 Bounce-chamber pressure and ENTHRU vs blow count, Annacis test site(from Sy and Campanella, 1993b) 1036.7 SPT N60 vs BPT N1, and Nb3O, Annacis and Richmond test sites(from Sy and Campanella, 1993b) 1046.8 Harder and Seed’s blow count ratio, NbC/N60 vs depth(from Sy and Campanella, 1993b) 1066.9 Effect of soil resistance on stress waves in pile 1096.10 Measured BPT wave traces, Annacis test site(from Sy and Campanella, 1993b) 1106.11 Effect of casing friction on BPT blow count (Nb30), Annacis test site(from Sy and Campanella, 1993b) 113xiLIST OF FIGURES(continued)6.12 Computed BPT-SPT correlations for different BPT shaft resistances (Rs)(from Sy and Campanella, 1993b) 1157.1 Cone penetration test data, Delta test site(from Sy and Campanella, 1993b) 1177.2 Corrected SPT (N60) and BPT (Nb30) blow counts vs depth, Delta test site(from Sy and Campanella, 1993b) 1187.3 SPT N60 vs BPT Nb30, Delta test site (from Sy and Campanella, 1993b) . . . . 1207.4 Computed BPT-SPT correlations with measured data from Delta, Annacisand Richmond test sites (from Sy and Campanella, 1993b) 1218.1 Corrected BPT blow count (Nb30), shaft resistance (Rs), and equivalentand measured SPT blow counts (Nw) vs depth, Annacis test site(from Sy and Campanella, 1993b) 124xliLIST OF SYMBOLSA Cross-sectional area of drill rodAW Drill rod with nominal dimensions 44.4 mm O.D. / 31.0 mm I.D.c Longitudinal wave speed in drill rod (typically 5120 m/s in steel)E Young’s modulus (typically 205 GPa for steel)Energy stored in diesel hammer bounce chamberE Energy loss due to compression of gases in diesel hammer combustionchamberE Hammer kinetic energy at impactHammer potential energyE1 Calculated SPT energy for ideal infinite rod conditionEr SPT rod energy calculated by force integration methodF Transferred energy in drill rodENTHRU Maximum transferred energyER Ratio of measured energy in rod to hammer potential energy (%)F Force in drill rodF2 Force integration method of energy calculationFV Force-velocity integration method of energy calculationg Gravitational acceleration (9.81 m/s2)h Height of hammer drop or strokeK1 Load cell location correction factor for SPT energyK2 Finite rod length correction factor for SPT energyxliiLIST OF SYMBOLS(continued)K Wave speed correction factor for SPT energyL’ Distance from load cell to bottom of sampler or pipem Mass of ram or hammerN Measured SPT blow count (blows/O.3 m)N60 Energy-corrected SPT blow countNb Measured BPT blow count (blows/O.3 m)NbC Bounce-chamber pressure-corrected BPT blow countNb30 Energy-corrected BPT blow countNW Drill rod with nominal dimensions 66.7 mm O.D. / 57.2 mm I.D.pp CPT pore pressureQ CPT tip resistance (bar)Rs Shaft resistance (kN) on Becker casingV Particle velocity in drill rodV, or v, Hammer impact velocityW Weight of hammerWd Work done or energy on pileX or x Distancea Hammer to rod area ratioe Energy loss factor during hammer fallTime duration of first compression pulse measured by load cell in SPTdrill rodxivACKNOWLEDGEMENTSThe writer wishes to thank his research supervisor, Professor R.G. Campanella,for his support and encouragement during the course of this research study. The writerwould also like to thank the other UBC civil engineering faculty for their helpfulcomments and the technical staff, especially Scott Jackson, senior electronicstechnologist, for valuable assistance in the field experiments. Helpful discussions withcolleagues and friends, including Steve Ahlfield, Lars Anderson, Ross Hitchman, MikeJefferies, Ken Lum, Bert Miner, Ernie Naesgaard, David Siu, Ray Stewart, Pat Stewart,Adrian Wightman and Li Yan, are much appreciated.The financial support of the STARS scholarship provided by the Science Councilof British Columbia in cooperation with Klohn Leonoff Ltd. is gratefully acknowledged.The support and interest of BC Hydro, BC Ministry of Transportation and Highways,Foundex Explorations Ltd., Greater Vancouver Regional District, and Klohn-CrippenConsultants Ltd. are also acknowledged.Most of all, the writer would like to acknowledge his wife, Diana, and children,Bettina, Leanne, Ellika and Sean, for their support, patience and understandingthroughout the research study. This thesis is dedicated to them.xvCHAPTER 1INTRODUCTION1.1 ORIGIN OF STANDARD PENETRATION TEST AND BECKERPENETRATION TESTThe dynamic testing and sampling of soils in-situ originated in 1902 in the UnitedStates when Charles R. Gow used a 50 kg mass to drive a 25 mm diameter pipe to obtain“dry” soil samples in wash boring (Fletcher, 1965). By the late 1920s and early 1930s, thestandard penetration test (SPT), as we know it today, was essentially developed with theintroduction of the split-barrel sampler by the Raymond Concrete Pile Co. in New YorkCity. The split-barrel sampler had dimensions of 51 mm O.D. by 35 mm I.D. and wasdriven into the soil with a 63.5 kg mass dropping 760 mm. The number of blows requiredto drive the sampler a distance of 300 mm, after an initial penetration of 150 mm, is referredto as the SPT N-value. It was recognised early that the SPT N-value could provide someinformation on the degree of compactness of the soil in-situ and, hence, could be correlatedto various engineering soil properties (Terzaghi and Peck, 1948). The test has received wideacceptance around the world, and the original procedure, with slight modifications, is nowstandardized in ASTM D1586-84 and in the ISSMFE (1988) International Reference Testprocedure for the SPT.Despite its popularity, the SPT has been plagued by problems associated with itsrepeatability and reliability. Although the basic SPT procedure is standardized, there are awide variety of equipment actually used for drilling, testing and sampling. Numerousobservations and studies have shown that the results of this supposedly standardized and1seemingly simple test are greatly influenced by the actual drilling and sampling operations(Fletcher, 1965; Mohr, 1966; Ireland et al. 1970; de Mello, 1971; Schmertmann, 1978).Many factors that affect the SPT N-value have been investigated (e.g. drilling technique,diameter of borehole, hammer drop technique and speed, size and length of drill rods, etc.),but the most significant factor is the amount of hammer energy delivered into the drill rods.Several investigators have measured the hammer energy in various SPT systems andfound considerable variabilities (Schmertmann et al. 1978; Kovacs and Salomone, 1982;Robertson et al. 1983; Riggs et al. 1984). The current method of SPT energy measurementas specified in ASTM D4633-86 and in ISSMFE (1988) consists of attaching a load cell nearthe top of the drill rods and measuring the force-time history during hammer impact. Thisrelatively simple method, however, has some shortcomings as indicated by severalinvestigators in recent years (Riggs et al. 1983, Kovacs, 1984; Clayton, 1990; Sy andCampanella, 1991a and 1993a).Despite its problems, the SPT continues to be the most widely used in-situ test inNorth America for foundation design and analysis in sands, silts and clays. It has beenempirically correlated to many useful soil parameters, both static and dynamic, includingliquefaction resistance (de Mello, 1971; Sanglerat, 1972; Seed et al. 1985; Skempton, 1986;Decourt, 1989). The well-known Seed’s simplified method of liquefaction potentialassessment based on field observations of the performance of sites during actual earthquakes,for example, uses the SPT N-value as the soil index.An important limitation of the SPT is that the N-values in gravelly soils areunreliable, and often too high, due to the large particle size relative to the diameter of thesampler. To overcome this deficiency, some investigators have suggested using the lowest2recorded N-value as representative of the soil stratum or formation (e.g. Fletcher, 1965).Others have conducted a more elaborate approach of recording blows for each 25 or 30 mmof sampler penetration to assess the effect of gravel particles on the N-value, and used somejudgement or “intuition” to reject or accept the measured SPT results (e.g. Stokoe et al.1988; Valera and Kaneshiro, 1991).In coarse-graineci soils, a large-scale dynamic penetration test, known as the Beckerpenetration test, has emerged in western North America as a most practical and economicaltesting technique. The test is performed with the Becker hammer drill, a rugged andspecially built hammer-percussion drill rig. The Becker hammer drill was developed in 1958in Alberta, Canada initially for seismic oil exploration in gravel sites. The drill is nowwidely used in geotechnical investigations for drilling, sampling and penetration testing incoarse-graineci granular soils. The drill uses a double-acting diesel pile hammer to drive aspecially designed double-walled casing into the ground. The casings come in 2.4 m or3.0 m lengths and are available in three standard sizes: 140 mm O.D. by 83 mm I.D.,170 mm O.D. by 110 mm I.D., and 230 mm O.D. by 150 mm I.D. The drill is more orless standardized, being manufactured by only one company, Drill Systems InternationalLtd., in Calgary, Alberta. The main advantage of the Becker hammer drill is its ability tosample or penetrate relatively coarse-grained soil deposits at a fast rate. The heavy-walledBecker pipe is robust and can often break up and penetrate boulders and weak bedrock(Anderson, 1968).The Becker casing can be driven open-ended with a hardened drive bit for drillingand sampling, in which case compressed air is forced down the annulus of the casing to flushthe cuttings up the centre of the inner pipe to the surface. This drilling technique, also3known as the reverse circulation process, is illustrated in Fig. 1.1. The continuous cuttingsor soil particles are collected at the ground surface via a cyclone which dissipates the energyof the fast-moving air-soil stream. At any depth, the drilling can be stopped and the open-ended casing allows access to the bottom of the hole for tube sampling, standard penetrationtest or other in-situ test, or for rock coring to be conducted. On completion of drilling, thecasing is withdrawn by a puller system comprising two hydraulic jacks operating in parallelon tapered slips that grip the casing and react against the ground.The Becker casing can also be driven close-ended, without using compressed air, tosimulate the driving of a displacement pile. The idea of driving the Becker casing close-ended like a pipe pile and using the recorded blow counts (blows per 0.3 m) to indicate soildensity was introduced in 1972 by Becker Drills Limited of Vancouver (now SDS DrillingLtd.). That test, then coined as the Becker denseness test, is now more commonly referredto as the Becker penetration test (BPT). The BPT has generally been observed to be lesssensitive to gravel particle size than the SPT because of the larger Becker pipe (140 mmO.D. and larger) compared to the SPT sampler (51 mm O.D.), and has, therefore, beenfound to be useful as an indicator of density in gravelly soils. As a result, the BPT iscommonly used for pile driveability and pile length evaluation, as well as for foundationdesign, usually through correlations with the SPT (Morrison and Watts, 1985). The BPTis also becoming accepted as a practical tool for liquefaction potential assessment in gravellysites, again through correlations with the SPT (Harder and Seed, 1986; Cattanach, 1987;Stewart et al. 1990; Harder, 1992; Sykora et al. 1992).In order to make use of the large world-wide foundation performance data basecurrently available for the SPT, such as the SPT-based liquefaction data base, there is a need4.a.• •..DFig. 1.1 Becker hammer drill system (from Harder and Seed, 1986)MASTAIRAIR COMPRESSOR—DIESEL HAMMERAIR OUTa• •0—------. —-a 0a 5a •‘ 9a 0• aao ‘0a •‘aa 0•a• a aVa.’,iiflN ‘V,r’4a,a0 a0a 0a Va%4%%,:-:’:_:!’aa a•a ••9 9 041a• 90a V43I• 0. a••l. •V•V‘a a•a •0,a • ‘ • a000• 00V0Ua•a0a . aa • a 0 • ••3 . aI a oaa•I0. 9• I. a 001I’0 9V V 0 •0 ap5for reliable BPT-SPT correlations. Numerous attempts have been carried out in the past tocorrelate the BPT blow counts to the SPT N-values. Most of these correlations, however,have limited applications since they do not take into account two important factors affectingthe BPT blow counts: the variable output of the diesel hammer used in the Becker systemand the soil friction acting on the Becker casing during driving.To overcome the variable hammer energy problem in the BPT, Harder and Seed(1986) proposed a method of using the measured peak bounce-chamber pressures at the topof the double-acting diesel hammer to correct the measured blow counts to a so-called“constant full combustion condition”. They then correlated the corrected BPT blow countsto corrected SPT blow counts. Although the Harder and Seed (1986) procedure is animprovement over existing BPT-SPT correlations, it still has serious limitations. Theirbounce-chamber pressure-correction method can not capture all the important variablesaffecting the BPT blow count, and their BPT-SPT correlation does not consider casingfriction in the BPT (Sy and Campanella, 1992b).1.2 OBJECTIVESThe objectives of this research were:1. To critically examine the existing methods of SPT and BPTenergy calibrations, and to investigate an alternative and morefundamental approach of determining the transferred energiesin both tests.2. To obtain reliable BPT-SPT correlations in sands which can beused to estimate equivalent SPT N-values from BPT blowcounts in gravelly soils.6To fulfil these objectives, experimental and numerical studies of the SPT and BPTwere conducted. The research involved performing a series of SPTs, BPTs and electric conepenetration tests (CPTs) in a controlled pattern at several research sites in GreaterVancouver, and included dynamic measurements of energy transfer in both the SPT andBPT. The measured transferred energies were used to correct the measured blow counts toa reference energy level in each test. Stress wave measurements and wave equation analyseswere also used to evaluate the effect of casing friction on the BPT blow count. Finally, newBPT-SPT correlations were derived which considered the energy transfer in both tests andwhich explicitly considered casing friction in the BPT.1.3 THESIS ORGANIZATIONChapter 2 reviews previous investigations on energy calibrations of the SPT and BPT,as well as available BPT-SPT correlations. In Chapter 3, the various methods ofcharacterizing energies in pile driving, or in any dynamic penetration test, are discussed.Chapter 4 presents the dynamic measurements and wave equation analysis of the SPTsobtained at McDonald’s Farm in Sea Island. Shortcomings in the current method of SPTenergy measurement are examined, and an alternative and more rational approach to SPTenergy determination is proposed.Chapter 5 presents the dynamic measurements and analysis of the BPTs conductedat the Kwantlen College site in Richmond. Limitations of the current BPT blow countcorrection procedure based on bounce-chamber pressure are discussed. An alternative andmore fundamental approach of correcting the measured BPT blow counts for the variablediesel hammer energy output is proposed.7Chapter 6 investigates the effect of casing friction on the BPT blow count, anddescribes the development of new BPT-SPT correlations from test data obtained at two testsites (viz. Kwantlen College in Richmond and Annacis north pier on Annacis Island), andfrom wave equation analyses. In Chapter 7, the proposed BPT-SPT correlations are verifiedby field measurements at another research site (Tower 5/4 in Delta) in which an experimentalmud-injection Becker penetration test was developed by Foundex Explorations Ltd. ofSurrey, British Columbia.Chapter 8 outlines the recommended procedure for estimating equivalent SPT N-values from BPT blow counts, together with example of an application of the proposedmethod. Finally, Chapter 9 summarizes the major findings and conclusions of this researchand suggests recommendations for future research.Two appendices are included. Appendix A provides additional background soilinformation and test data from the research test sites. Appendix B presents results of theCAPWAP analyses of the BPT performed by Goble Rausche Likins and Associates, Inc. ofSeattle, Washington.8CHAPTER 2PREVIOUS INVESTIGATIONS2.1 SPT ENERGY CALIBRATIONSIn early studies of the SPT energy, Kovacs et al. (1977, 1978) and Kovacs (1979)used light scanner and reflection technique to measure the height of hammer fall and thevelocity just before impact. These measurements allowed them to calculate the potentialenergy of the hammer drop and the kinetic energy of the hammer just before impact. Theyfound that the hammer energy just before impact was always less than the potential energyof the hammer drop due to energy losses in the hammer system. They investigated factorswhich can affect the hammer energy, including hammer fall height, rope age, number ofwraps of the rope around the cathead, speed of rope release, cathead speed, drill rodinclination and different types of hammer. Their data suggested a linear relationship betweenSPT N value and hammer energy at impact. They further proposed that a “standard energy”be established based on US practice and that all drill rigs be calibrated by adjusting thehammer fall height to deliver that “standard energy”.In the late 1970s, Schmertmann and his co-workers at the University of Floridaconducted pioneering research into the statics and dynamics of the SPT by carrying outtheoretical and experimental studies (Palacios, 1977; Schmertmann, 1978 and 1979;Schmertmann and Palacios, 1979). In their field experiment on the SF1’, they incorporatedhollow-centre, strain gauge load cells near the top and bottom of the drill rods to measurethe force-time histories of the stress waves. The force data were used to calculate energytransfer in the rods and the energy loss in the sampling process. They proposed that a single9force-time load cell located near the top of the drill rods be used to determine the energyentering the rods.The force measurement concept of SPT energy determination is shown schematicallyin Fig. 2.1. On hammer impact, a compression stress wave is generated which travels downthe drill rods at a constant speed of about 5120 m/s in steel. Upon reaching the bottom ofthe sampler, the compression wave reflects as a tension wave back up the drill rods. At thetop of the drill rods (or anvil), the upward travelling tension wave reflects once again withopposite sign, this time from tension to compression. The reflected compression wave fromthe anvil then travels down the drill rods a second time, but with much reduced amplitude.An idealized force time history recorded by a load cell near the top of the SPT drillrods is shown in Fig. 2.2. The sign convention is positive force for compression wave, inwhich the particle motion is in the same direction as the direction of wave propagation, andnegative force for tension wave, in which particle motion is in the opposite direction to wavepropagation. Zone 1 in Fig. 2.2 is the impact compression pulse sensed by the load cell.It has a duration of approximately 2L’/c, where L’ is the total length of the drill rods andsampler below the load cell and c is the speed of wave propagation in the rods, typically5120 m/s in steel. The 2L’/c is the theoretical time for the impact wave to travel from theload cell near the top of the rods down to the sampler and return to the load cell location.This time (indicated by Point 2 in Fig. 2.2) also marks the arrival of the tensile wavereflection from the sampler, commonly referred to as the “tension cutoff time”.Schmertmann and Palacios (1979) found that after hammer impact, the hammer and rodsremain in contact until the arrival of the tensile wave reflection from the sampler, whichcauses the rods to pull away from the hammer and effectively stops further transfer of energy10HAMMERri ANVILC.,zLu-JO00 TIMELOADCELLL’RODFig. 2.1 SPT energy measurement concept using load cell (from ISSMFE, 1988)11FORCE First compression pulse or wave© Cutoff time at the arrival of the first tension pulse® First tension pulse reflected from the sampler43 Second compression pulse reflected from the anvilFig. 2.2 Idealized force-time waveform recorded by load cell in SPT drill rod12from hammer to rods. They indicated that the longer the drill rods, the longer is thehammer-rod contact time and the more hammer energy that enters the rods.Schmertmann and Palacios (1979) showed that the energy entering the drill rods (Er)can be calculated by integration of the square of the measured force time history within thetime limits of the first compression pulse (i.e. integration is valid up to t=2L’Ic afterimpact) times a rod material constant:[2.1] E =—s— f [F(t)]2 dtwhere c is the velocity of longitudinal wave propagation in the rod, E is the Young’smodulus of the rod, A is the cross-sectional area of the rod and F(t) is the measured force-time history. The quantity, EA/c, is a material property, commonly called the impedanceof the drill rods. They found that due to energy loss to heat during hammer impact as wellas energy trapped in the anvil, the energy entering the drill rods, i.e. ENTHRU, was lessthan the hammer impact energy, and it was this ENTHRU, not the energy in the hammerat impact, that produced the sampler penetration that determined the SPT N-value. Theyshowed field data to confirm that N-value varies inversely with the energy delivered into thedrill rods.A SPT energy calibrator was subsequently developed and made commerciallyavailable by Binary Instruments, Inc. (Hall, 1982). The system consisted of a load cellattached near the top of the drill rods and a data processing instrument which calculated theenergy at the transducer location in the rods. The transferred energy for each hammer blowwas read directly from the instrument as a percentage of the theoretical free-fall hammer13energy of 475 J. The SPT calibrator used Eq. [2.11 to calculate the energy in the rods andrequired the input of the appropriate cross-sectional area of the drill rods.Riggs et al. (1983) reported problems with the SPT calibrator in their studycomparing the energy performances of a new automatic hammer and a string-cut free-fallsafety hammer. Their measured energy values were erratic with some recorded energy ratioswell over 100%. They subsequently suggested the need for “calibration of the calibrator”.In a discussion to Riggs et al. (1983), Kovacs (1984) suggested that the erraticcalibrator energy values could be due to either premature tensile wave reflections or harddriving compression reflections from the sampler, both of which would yield unrealisticintegration times for calculating the energy in the rods. In the former case, the apparentintegration time would be too short, resulting in too low an energy value, while in the lattercase, the integration time would be too long, resulting in too high an energy. The aboveillustrates the importance of knowing the actual integration time used in calculating theenergy from Eq. [2.1], a feature not available on the Binary SPT calibrator.Bosscher and Showers (1987) conducted a wave equation analysis of the SPT in anattempt to study the effect of soil type on the input energy in the drill rods. Their computedtransferred energies based on Eq. [2.1] were much higher than the kinetic energy of thehammer at impact! This anomaly again illustrates the problem in using the force integrationmethod to calculate energy and in the selection of the duration of the first compression pulsefor use in Eq. [2.1].More recently, Robertson et al. (1992) described a PC-based SPT energymeasurement system developed at the University of Alberta which consists of attaching astrain-gauged AW rod section to the top of the drill rods and measuring the force time14history. Although the strain-gauge technology appeared to offer several practical advantages,several anomalies were noted fri their energy measurements as discussed by Sy andCampanella (1993a).The current method of SPT energy measurement as specified in ASTM StandardD4633-86 and in the ISSMFE (1988) International Reference Test procedure is based on theSchmertmann force measurement concept and the energy is calculated from:AtcKKK[2.2] E. = 1 2 c j [F(t)]2 dtEAwhich is similar to Eq. [2.11 but with three correction factors applied. K1 and K2 aretheoretical correction factors to account for the load cell location in the rods and the finitelength of the drill rods, respectively. The third factor, K, is to correct the theoretical wavespeed in steel to the so-called “actual” wave speed as determined from the measured force-time history. The corrected energy (F.1) from Eq. [2.2] then refers to the energy in the firstcompression pulse for the ideal case of an infinite rod. The bases for the three correctionfactors are discussed below.Palacios (1977) indicated that attaching the load cell within the drill rods at somedepth below the impact point and the finite length of the drill rods itself both result inapparent tension cutoff times less than those expected at the top of an ideal infinitely longrod. These effects result in “premature” cutoff of energy transfer from hammer to rod, andconsequently, K1 and K2 correction factors are greater than unity. Conceptually, these twofactors “correct” the measured energies to the ideal infinite rod condition, i.e. independent15of load cell location and rod length, so that the corrected energies can be compared betweendifferent SPT systems.The values for K1 and K2 recommended in ASTM D4633-86 and similar correctionfactors in ISSMFE (1988) are based on the theoretical energy transfer derivations by Palacios(1977) and Yokel (1982), respectively. Both derivations are based on the force integrationmethod of energy calculation and do not allow for further energy transfer from hammer torods beyond 2L’Ic (duration of the first compression pulse). To date, no experimental datahave been published to support these theoretical K1 and K2 values.The third correction factor, K, is calculated from the ratio of the “actual” wave speedto the theoretical wave speed, where the “actual” wave speed is determined from themeasured tension cutoff time. This wave speed correction factor has been controversial forsome time and has caused confusion (Riggs et al. 1984; Clayton, 1990). The correction isbased on the assumption that the total duration of the first compression pulse (see Fig. 2.2)should equal the theoretical 2L’/c trip time. Invariably, it was found that the measured pulseduration was always greater than the theoretical 2L’/c, suggesting that the “actual” wavespeed was less than 5120 m/s. Hence the K factor is used to somehow “reduce” themeasured compression pulse duration to match the theoretical 2L’/c and its value is usuallyless than unity. Riggs et al. (1984) indicated that this correction causes the complete forcetrace to be contracted or compressed along the time ordinate. They argued that the longerobserved trip time is a result of secondary compression return at the tail of the curve and notfrom a slow stress wave velocity. They then suggested that the theoretical trip time bemaintained and that the compression tail or “blip” beyond that time be discounted in theenergy calculation. Riggs et al. (1984), however, acknowledged that they did not have16evidence to support their suggestion. In any case, Clayton (1990) used this approach andsimply cut off any energy transfer beyond the theoretical 2L’/c in their calculation of SPTenergy using the force integration method.The measured energy (Es) is commonly expressed as energy ratio (ER) or percentageof the theoretical free-fall SPT hammer potential energy of 475 3. For design and analysis,the measured SPT N-values are corrected to a reference energy level of 60% of thetheoretical free-fall hammer energy, using:ER.[2.3] N =N—60 60where N60 is the N-value corrected to 60% reference energy level, N is the measured SPTN-value, and ER, is the measured or estimated energy ratio in percent. The 60% energyratio appears to represent a historical average for the different SPT systems used in most ofthe SPT-based empirical correlations (Seed et al. 1985; Skempton, 1986). This energycorrection of SPT blow count is now widely accepted in practice.Figure 2.3 illustrates the three types of SPT hammers employed in this researchstudy, i.e. donut, safety and automatic trip hammers. These three types are also the mostwidely used in North America. Several investigators have compiled typical energy ratios forthe different SPT hammer systems in common use around the world, such as those shownin Table 2.1 from Robertson et al. (1992).174 SLEEVENW RODNW TO AWAWRODCOLLAR EYE 80 LT/HAMMERANVILHAMMERSPROCKETGUIDE RODHYDRAULIC CHAINWITH CAMSADAPTORAW RODSPROCKET-HYDRAULIC MOTOR•SPRING-ANVIL4W RODDONUTHAMMERFig. 2.3AUTOMATIC TRIPHAMMERSAFETYHAMMERDifferent SPT hammers used in this study18Table 2.1 Generalized SPT energy ratios (after Robertson et al. 1992)Location Hammer Release ER1 (%) ERI60North and South Donut 2 turns of rope 45 0.75America Safety 2 turns of rope 55 0.92Automatic Trip 55-83 0.92-1.38Japan Donut 2 turns of rope 65 1.08Donut Auto-trigger 78 1.30China Donut 2 turns of rope 50 0.83Automatic Trip 60 1.00United Kingdom Safety 2 turns of rope 50 0.83Automatic Trip 60 1.00Italy Donut Trip 65 1.08As Robertson et al. (1992) indicated, these generalized energy ratios and recommendedcorrections for SPT practice represent global corrections and should be used with caution.For all important projects involving the SPT, the energy transfer should be measured.2.2 BPT ENERGY CONSIDERATIONSThere are two basic types of Becker drill rigs: the older HAV 180 and the newerAP1000. The main difference between the two rigs is the way the hammer is mounted onthe mast and the way the hammer is raised or lowered onto the pipe. The HAV18O has atwo-piece “telescopic” or sliding mast and is a more compact rig. The AP1000 rig is larger,with a single long mast, and is more elaborate, containing several additional features tofacilitate drilling and testing. One such feature on the AP1000 is an air blower orsupercharger which can be turned on to pump more air into the combustion chamber, therebyincreasing the hammer combustion efficiency. Both rigs use the same International19Construction Equipment, Inc. (ICE) model 180 diesel pile hammer but with slightly differentdriving cap or “spout” design. The spout rests directly on top of the double-walled casingand has an inlet port for air injection into the annulus of the casing and an outlet port for soilretrieval from the drill hole.The Becker drive casing is made up of two heavy-walled pipes arrangedconcenthcally, with one male and one female tool joints, and tapered threads, at the end.In the older design, the two pipes are welded together and separated by four straps orspacers running the length of the casing, and can be handled as one piece of pipe. In thenewer design, the inner pipe “floats” inside the outer pipe and only the outer pipe absorbsthe direct impact of the hammer.Figure 2.4 shows the operating principle of the double-acting, or closed-top, atomizedfuel-injection diesel pile hammer. On the downstroke and just before ram impact, a highpressure fuel injection system atomizes the fuel as it is injected into the combustion chamber.Combustion starts immediately and imparts energy to drive the impact block (or anvil) andto lift the ram up to the top of its stroke for the next cycle. The top of the hammer housingis closed off and connected to compression tanks, such that as the ram rises on the upwardstroke, it compresses the air trapped in the “bounce chamber”. The air in the bouncechamber acts like a spring, storing energy on the upstroke and imparting it to the ram on thedownstroke. The bounce chamber also shortens the stroke, which leads to an increase inblow rate compared to an open-top condition.The Becker hammer, like all diesel hammers, gives variable energy output dependingon the combustion conditions and soil resistances. Anything that affects combustion, suchas air-fuel mixture, temperature and pressure, will affect the hammer energy output. In fact,20BOUNCE CHAMBERRAMIMPACT BLOCKCUSHIONHELMET‘PILETOP OF PORT CLOSURE,STROKE COMBUSTIONIMPACT EXHAUST SCAVENGINGFig. 2.4 Operating principle of double-acting atomized fuel injection dieselpile hammer (from Sy and Campanella, 1992a)21the Becker rig has an adjustable lever or throttle control which allows the operator to controlthe amount of fuel injected into the combustion chamber. Even if constant combustionconditions can be maintained, the hammer energy output will still depend on the soilresistance. In soft ground driving conditions, a large portion of the combustion gas energyis expended to accelerate the anvil downward, reducing the energy available for lifting theram and resulting in lower stroke, or lower bounce-chamber pressure, for the next cycle.On the other hand, in hard driving conditions, the anvil movement decreases and more gasenergy is available to propel the ram upward, resulting in a higher stroke or higher bounce-chamber pressure.The ICE 180 hammer has a ram weight of 7.67 kN and a maximum physical strokeof 0.96 m. The hammer operates at a blow rate of 90 to 95 blows per minute at maximumstroke. The manufacturer’s rated energy for the hammer is 11.0 kJ, equivalent to a single-acting hammer stroke of 1.43 m. ICE closed-top diesel hammers are rated by themanufacturer in a manner similar to that used for double-acting steam or air hammers, inwhich the potential energy of the actual ram stroke is added to the energy of the steam orair force applied to the ram on its downstroke, to obtain the total potential energy of thehammer. For the double-acting diesel hammer, the rated potential energy is equal to theweight of the ram (W) multiplied by the actual stroke (h) plus the energy stored in thebounce chamber (E) that accelerates the ram downward, i.e.[2.4] EPE = Wh + EBCThis stored energy (EBC) is calculated by using gas laws for adiabatic conditions, given thedimensions of the bounce chamber and the maximum bounce-chamber pressure. The22maximum bounce-chamber pressure and, therefore, the maximum physical stroke, iscontrolled by the weight of the hammer housing and is reached when the housing lifts or“racks” on the upstroke. The effect of combustion is ignored in the calculations.Based on the above assumption that total potential energy is the sum of the actual ramstroke energy and the energy stored in the bounce chamber (Eq. [2.41), the hammermanufacturer developed charts relating peak bounce-chamber pressure to the equivalent totalpotential energy at the top of ram stroke, for different lengths of hose used in recording thebounce-chamber pressure. Figure 2.5 shows such a chart developed by ICE for the Model180 diesel hammer. In pile driving analysis, the estimated energies from Fig. 2.5 aresometimes used in a dynamic formula to determine the pile capacity for a given set, or piledisplacement per blow. This practice can be misleading and dangerous, since not all thetotal potential hammer energy is available to do work on the pile (Sy and Campanella,1992a).In an effort to come up with a practical technique for evaluating liquefaction potentialin gravelly soils, Harder and Seed (1986) investigated the Becker penetration test andmeasured the peak pressures in the hammer bounce chamber. They suggested that just asthe air in the bounce chamber acts as a spring in storing potential energy on the upstroke,the air-fuel mixture in the combustion chamber acts as a cushion during the downstroke,slowing down the ram and resulting in energy loss. Using gas laws, they calculated thisenergy loss due to compression of gases in the combustion chamber (F). Then, againignoring the effect of combustion, they determined the net kinetic energy at impact (E)simply from23Fig. 2.5ICE Model 180 Diesel Pile HammerBOUNCE CHAMBER PRESSURE vs. EQUIVALENT WH ENERGYSea Level To 2000’ Elevation25CuJDCCCl)uJaUi< 150Ui0zD0 10Energy chart for ICE Model 180 diesel hammerEQUIVALENT WH ENERGY—FT. LBS.24[2.5] E= EPE —They found that the calculated net kinetic energy at impact is substantially reduced, andsuggested that it is this kinetic energy at impact, not the total potential energy of the ram,that appears to control the resulting blow count or penetration resistance of the Beckercasing.Harder and Seed (1986) then proposed an empirical but ingenious method of usingthe peak bounce-chamber pressure to correct the BPT blow counts to a reference combustioncondition. Their proposed blow count correction procedure is shown in Fig. 2.6. Usingblow count and bounce-chamber data collected at various sites, they observed that as thecombustion efficiency increases, i.e. as bounce-chamber pressure or hammer energyincreases, the blow count decreases according to the paths (blow count correction curves)shown in Fig. 2.6. Each curve represents a constant resistance condition, i.e. all pointslying on the same curve have the same soil resistance but different hammer combustion orenergy efficiencies. At constant combustion condition, however, bounce-chamber pressureincreases with increasing blow count, and the data points tend to lie on lines somewhatparallel to line A-A shown. Harder and Seed suggested that line A-A, which they called the“constant combustion condition rating curve”, be used as the reference line for correctingthe field blow counts obtained on 170 mm diameter pipe with AP1000 type Becker drill rig.Since the bounce-chamber pressure is affected by atmospheric pressure, they furtherproposed a correction for atmospheric pressure other than the standard 100 kPa at sea level.To use the Harder and Seed’s BPT blow count correction chart in Fig. 2.6, the fielddata point is first located on the graph, using the measured blow count and corresponding251000rl)1000I—z0C) -0-J10=I—1 I I I I I I f I I I I I0 100 150 200 250BOUNCE CHAMBER PRESSURE (kPa)Fig. 2.6 BPT blow count correction chart based on bounce-chamber pressure(after Harder and Seed, 1986)BLOW COUNT CORRECTION CURVES/ FOR REDUCED COMBUSTIONEFFICIENCIESACONSTANT COMBUSTION CONDITIONRATING CURVE ADOPTED FORCALIBRATIONAI I I I (5026peak bounce-chamber pressure at sea level, then following the appropriate correction curveor path down to the rating curve A-A, the corrected blow count, Nba, is obtained. Twoexamples are shown in Fig. 2.6, the empty circle and empty square representing twomeasured data, and the filled circle and filled square giving the corresponding blow countsafter correction.The attractiveness of the Harder and Seed (1986) BPT blow count correctionprocedure is that peak bounce-chamber pressure can be measured in the field simply witha pressure gauge at the end of a length of hydraulic hose connected to the bounce-chamberoutlet port. Although easy to measure, the bounce-chamber pressure reading is not alwaysreliable, since it can be affected by fluid accumulation (i.e. oil and water from the bouncechamber) in the hose and by the hose length, diameter, fittings and adaptors.2.3 BPT-SPT CORRELATIONSNumerous correlations have been proposed in the past to correlate the BPT blowcounts to SPT N-values. The earliest correlation, shown in Fig. 2.7, was based on BPT andSPT data compiled from many sites in British Columbia in the 1970s. The sites wereunderlain by various soil deposits: sand, silt, and gravelly sand. The BPTs were conductedwith the 140 mm diameter casing, driven close-ended. Measured blow counts from side-byside BPT and SPT conducted at the same site were simply plotted as shown in Fig. 2.7.Although a 1:1 BPT-SPT relationship was suggested, there was considerable scatter in thecorrelation.Based on their experiences with BPTs using the 140 mm diameter casing, Morrisonand Watts (1985) suggested the relationship:27Fig. 2.7aaS.be3azD00-JC.120CANADIAN DATA FROM BECKER DRILLS, INC FILES5.5 - INCH 0. 0 CLOSED BECKER BITSBPT-SPT correlations by Becker Drills (from Harder and Seed, 1986)O VIJLCAN WAY, RICHMOND, B.C. CR. A.SPENCE LTD.)o LYNN CREEK, N. VANCOUVER, B.C.O HUNTER CREEK, NEAR HOPE, B.C.NORTH VANCOUVER, B. C. CR. A. SPENCE LTD., 1973)POWELL RIVER, B.C. (RIPLEY, KLOHN, S LEDNOFF LTD., 973)• NEW WESTMINIST!R, 9.C. (RIPLEY, XLOHN, a LEONOFF LTD., 1973)• IdINORU BLVD., RICHMOND, B.C.• STEVESTON HIGHWAY, RICHMOND, B.C. CR. U. HARDY a ASSOC. LTD., 1975)BECKER BLOWCOUNT, N1 (blows/fool)28[2.6]= NBJ,2. + 4where and NBII’ are uncorrected SPT and BPT blow counts, respectively. Theyindicated that Eq. [2.6] represented an average correlation of extensive data but with a widescatter.Other early BPT-SPT correlations with similar scatter were summarized by Harderand Seed (1986). A big part of the scatter was due to differences in equipment andprocedure used for the SPT and BPT at different sites. Another problem was that somecorrelations were developed in coarse gravelly subsoils for which the SPT N-values werehighly questionable. Perhaps more importantly, the variable energies in the SPT, as wellas in the BPT, were not always considered.Harder and Seed (1986) proposed an improved correlation between the BPT and SPT,based on bounce-chamber pressure measurement during the BPT. Their correlation is shownin Fig. 2.8, which shows the bounce-chamber pressure-corrected BPT blow count (NbC)plotted against the energy-corrected SPT blow count (N60). The correlation was developedfrom test data at three sites in sand and silt subsoils, where the SPT N-values would not beaffected by large gravel particles. The 170 mm size casing was used in their BPTs. Theirtest data, however, were limited to 15 m depth and the BPT-SPT correlation did notexplicitly consider soil friction on the BPT casing.29Erl)0(I)0-o0_____________________ __________ ___________ ______________________zF0CI)Fig. 2.8 Correlation between corrected BPT blow count (N) and corrected SPTblow count (N) (after Harder and Seed, 1986)100HARDER & SEED (1986)A SALINAS• THERMALITO-. SAN DIEGO80 —-60-:40-20— ••)/I I0I I I20I I I I I I40 60 80BPT Nb (blows/O.3m)100 12030CHAPTER 3ENERGIES OF IMPACT PENETRATION TEST SYSTEMSThere are three basic methods of characterizing energy in pile driving, or in anyimpact penetration test systems, as shown schematically in Fig. 3.1:1. potential energy of the ram,2. kinetic energy of the ram at impact, and3. energy transferred into the pile or drill rod.For drop hammer, single-acting air and diesel hammers, the potential energy (E)can be determined by simply observing or measuring the height of the hammer drop (h), andfrom the known mass of the ram (m),[3.1] EPE = mghwhere g is the gravitational acceleration. For hydraulic hammer, double-acting air and dieselhammers, the additional force exerted by the hydraulic or air pressure applied to the ram onits downstroke is added to the energy of the actual ram stroke to obtain the total potentialenergy of the hammer.For the 63.5 kg hammer falling over 760 mm in the SPT, the potential energy is,therefore, 475 J. In the SPT, this potential energy is ideally constant, if the height ofhammer drop can be kept constant. In the BPT, however, the total potential energy of theICE 180 diesel hammer varies with each hammer blow, as discussed in Chapter 2. As31hPE=mghKE=--mvFig. 3.1 Methods of characterizing energy in pile drivingENTHRU FV dt32shown in Fig. 2.5, this potential energy can be determined by measuring the peak pressurein the bounce chamber for every hammer stroke.The kinetic energy of the hammer at impact (EJ can be determined by measuringthe velocity of the ram immediately before impact (vi), then[3.2] E = ! mvRadar equipment is nowadays readily available to track the velocity of a visible ramduring hammer operation. The ratio of the kinetic energy to the potential or rated energyof the hammer then gives the hammer efficiency, i.e. an indication of hammer performance.Hammer efficiencies (EKE/E) between 35 and 70% were determined by Kovacs etal. (1977) in their experimental study of a donut hammer and a safety hammer.Schmertmann (1978) also found kinetic energies at impact anywhere from 30 to 80% of thefree-fall potential energy in an extensive research study of the SPT at the University ofFlorida.In a double-acting diesel hammer, the impact velocity can not be readily measuredsince the ram is almost completely enclosed in the hammer housing. It can, however, beestimated as discussed in Chapter 2. For the ICE 180 hammer used in the Becker system,Harder and Seed (1986) showed that the net kinetic energy at impact, taking into account theenergy loss due to compression of the gases in the combustion chamber, is significantlyreduced compared to the total potential energy of the ram, particularly at low ram stroke orlow bounce-chamber pressure.33The third method of characterizing energy is to measure the energy actuallytransferred into the pile or rod. The energy transmitted into a rod can be derived from thefundamental energy-work equation[331 Wd = fFdxwhere W4 is the total energy or work done on the pile or rod, F is the variable force actingover an increment of displacement, dx. Eq. [3.3] can also be expressed as a function oftime:[3.4] EQ)= f F(t) V(t) dtwhere E(t) is the energy transferred into the pile or rod as a function of time, F(t) is theforce and V(t) =dx/dt is the corresponding particle velocity. Thus if force and velocity timehistories are measured at or near the top of the pile or rod, the transferred energy resultingfrom a hammer impact can be computed from Eq. [3.4]. The maximum transferred energyfrom Eq. [3.4], commonly called ENTHRU, represents that part of the hammer energyavailable to do work on the pile. The ratio of ENTHRU to the potential or rated energy ofthe hammer is referred to as the energy transfer ratio or efficiency, and it gives an indicationof the complete drive system performance or efficiency. The energy transfer ratio,therefore, accounts for all the energy losses in the hammer, cushion, helmet, etc. above thepile or drill rod.In practice, the transferred energy in the pile is determined by measuring force andacceleration near the pile head for each hammer blow, and integrating the acceleration timesignal to obtain the velocity time history. This procedure is routinely used in dynamic34monitoring of pile driving as recommended in ASTM D4945-89. Extensive experience frompiling indicates that it is the energy actually transferred into the pile, rather than the potentialor kinetic energy of the ram, that directly affects the driving resistance or blow count of thepile.From wave mechanics theory, it can be shown that for an impact wave travelling inone direction, the force and particle velocity at any point in a uniform rod are proportional(Timoshenko and Goodier, 1970), i.e.[3.5] F(t) = V(t) -where the constant of proportionality, EA/c, is the impedance of the rod. For wavepropagation in a uniform rod with soil resistance acting only at its toe, like in an idealizedSPT, the above proportionality relationship will hold from the time of impact to the time ofarrival of the wave reflection from the toe, i.e. over a duration of approximately 2L’/c. Inthis case, Eq. [3.5] can be substituted into Eq. [3.4], either for force or velocity, to obtainthe following equations:[3.6] E = - /V(t)2 dtor[3.7] E = —s— /F(t)2 dtEA0where t is approximately 2L’/c.35Eqs. [3.61 and [3.7] indicate that the energy at a point in a uniform rod with no sideresistance can be computed given only one measured quantity, i.e. either velocity or forcetime history. Both equations inherently assume proportionality between force and particlevelocity at the measurement point in the rod during the first compression pulse and requirethat the time limits of the first compression pulse (àt) be predetermined. Note that Eq. [3.7]is essentially the same as Eqs. [2.1] and [2.2] currently used for SPT energy measurementin accordance with ASTM D4633-86 and ISSMFE (1988).It is important to know which energy one is dealing with in an impact penetrationtest, and what assumptions or limitations are associated with that energy measurement. Inthe existing method of SPT energy measurement, the transferred energy is determined byforce measurement (albeit with some assumptions or shortcomings as discussed earlier) andthe two correction factors, K1 and K2, “correct” the measured energy to that at the top of anideal, infinitely long rod. This procedure is analogous to determining the kinetic energy ofthe SPT hammer impact on the anvil, such that it is independent of rod length. In otherwords, the corrected energy (Ei) may not be the actual energy transferred into the drill rod,and careful consideration should be given to the subsequent use of this energy in design. Infact, there is an accompanying note (rather obscure) in both ASTM D4633-86 and ISSMFE(1988) advising that to obtain the actual energy entering the rods, one should divide E1 byK2.In a similar manner, the Harder and Seed’s (1986) approach for normalizing BPTblow counts based on bounce-chamber pressure measurement assumes that the kinetic energyof the Becker diesel hammer directly affects the resulting blow count. Bounce-chamberpressure, although useful as an indicator of diesel hammer performance, can not account for36energy losses in the driving system (helmet, cushion, spout, etc.) below the anvil. Thiswould explain why the blow count correction procedure proposed by Harder and Seed (1986)appeared to work only for the AP1000-type Becker drill rig, but not for the other HAy 180-type rig in their study.The SPT and BPT, like all dynamic penetration test systems, involve stress wavepropagation in a slender rod due to hammer impact, similar to pile driving. Thus theprinciples of wave mechanics or pile dynamics should be applicable to these tests.Furthermore, transferred energies due to hammer impacts in these tests should ideally bedetermined by force and acceleration measurements. This approach will avoid severalshortcomings inherent in the existing methods, and will also provide a unified approach fordetermining the transferred energies in all impact penetration systems, i.e. pile driving, SPT,BPT, and other dynamic cone penetration tests. Accordingly, force and accelerationmeasurements of the SPT and BPT were performed in this research study as discussed inChapters 4 and 5, respectively.37CHAPTER 4DYNAMIC MEASUREMENTS AN]) ANALYSIS OF SPT4.1 FIELD EXPERIMENT AT MCDONALD’S FARMThe initial SPT research was conducted on November 16, 1989 at McDonald’s Farm,an abandoned farm on Sea Island south of Vancouver. Sea Island is located in the FraserRiver delta and is contained by a system of dykes to prevent flooding. The site isapproximately level. The mean groundwater table is about 1.5 m below ground surface andvaries with the tidal fluctuations of the adjacent Fraser River.The soil conditions at McDonald’s Farm consist of 2 m of soft organic clayey siltoverlying a 2.5 m thick zone of silty fine sand underlain by about 11 m of medium to coarsesand. The sand stratum is variable in density with occasional seams of silt. Underlying thesand is a deep deposit of normally consolidated silty clay which extends to a depth of about105 m above very dense glacial deposits. Figure 4.1 shows piezometer cone penetration test(CPT) data at the site.The SPT’s were conducted between 1.5 m and 9.1 m depths in a mud rotary holedrilled with a Gardner Denver 1000 drill rig. The SPT was performed in accordance withASTM D1586-84 using a safety hammer with two turns of rope around the cathead. Figure4.2 shows dimensions of the safety hammer used. A modified Binary Instruments Inc. SPTcalibrator (Hall, 1982) was used to measure the force-time history of the impact wave in thedrill rod with a load cell. In addition to the force transducer, an accelerometer was attachedadjacent to the load cell to record accelerations in the rods. Both instruments arepiezoelectric-type transducers which are robust and have fast dynamic response. The38CONE BEARING STRESS SLEEVE FRICTION FRICTION RATIO BEHIND TIP• pp INTERPRETEDQt (bar) Fe (bar) Gt/Fs=Rf (%) U2(n.of water) PROFILE0 250 0 1 0 2.5 0 1000 0 0 0 0clayeySILTSAND10 10 10 10siltySAND10C.siltya)SAND20 20 20 siltyzw20 20CLAY30 30 30 30Fig. 4.1 Cone penetration test data, McDonald’s Farm test site(after Sy and Campanella, 1991a)39SLEEVE — 5.5811 O.D.4.99” I.D.NW ROD - 2.63” O.D.2.25” I.D.EYE BOLTHAMMERANVIL - 441”O.D.6”40”6111.9”48.5”711 NW TO AW ADAPTORAW ROD- 1.75 0.0.1.22” 1.0.Fig. 4.2 SPT safety hammer used at McDonald’s Farm(from Sy and Campanella, 1991a)40transducers were attached 1.9 m below the anvil. The force and acceleration measurementsof the SPT blows were recorded on a Nicolet 4094 digital oscilloscope with a 15 bit A/Dresolution. For both channels, data samples were obtained at a frequency of 100 kHz whichcorresponds to a sampling interval of 0.01 ms.4.2 MEASURED STRESS WAVESStress wave measurements of two typical SPT blows, one at 1.5 m depth in the softsilt and another at 9.1 m depth in the medium to dense, fine to medium grained sand, arepresented and discussed in detail below.Figure 4.3 shows the stress wave measurements for the first blow of the SPT at1.5 m depth where the recorded N value was 2. From tape measurement, the SPT samplerpenetrated 200 mm during this blow. The four time histories shown in Fig. 4.3 are themeasured force, measured acceleration, velocity obtained by integration of the accelerationwave trace, and the calculated energy from time integration of force times velocity. Thesign convention used is positive force for compression wave and negative force for tensionwave, and positive acceleration or velocity for downward motion and negative accelerationor velocity for upward motion. The measured peak compression force is 86 kN and themaximum acceleration is over 2500 g. This peak acceleration is much higher than istypically measured in piles (less than 1000 g) because of the steel-to-steel impact in the SPT.The velocity in the rod at impact is 3.4 m/s, but the maximum velocity reached 4.6 rn/swhen the initial compression pulse reflected back from the sampler tip as a large tensionwave because of the very small soil resistance acting on the sampler. At the end of the20 ms record, the drill rods were still moving down at a velocity of about 3.0 rn/s.415.0w)I I II I I I I I I I I I I I I I I I0 5 10 15 20Fig. 4.3TIME (ms)Measured force, acceleration, velocity and energy traces for SPT blow 1at 1.5 m depth, McDonald’s Farm (after Sy and Campanella, 1991b)42120—80 —40 —0 f’IF,250012500—1250—2500zuJ00Uz0UJ-J000)00-JUJ>-)>-0UJzU4.03.02.01.00.0—300 —:Ey’\Integration of this velocity trace yields a calculated displacement of only 64 mm at 20 ms.Obviously the record length of 20 ms was not long enough to capture the complete event forthis blow. Finally, the maximum transferred energy (ENTHRU) is 200 J, which is 42% ofthe theoretical free-fall hammer energy of 475 J.The same blow above is replotted in Fig. 4.4, the upper plot of which shows theforce (F) and velocity times impedance (VEA/c) wave traces. To calculate the impedance,the cross-sectional area of the AW rod (800 mm2), rather than that of the larger NW rod orthe load cell, was selected. This type of proportional stress wave plot is commonly used inpile driving and it highlights several key features. First of all, if force and velocity areproportional within the first compression pulse as would be expected for wave propagationin a uniform rod with only toe resistance, they will plot on top of each other. Figure 4.4shows that proportionality does not exist at the two velocity peaks in the primarycompression pulse. The first velocity peak at 0.45 ms is due to the hammer impact, and theeffect of the hammer-anvil geometries likely causes the separation of the force and velocitypeaks in this region. The second velocity peak at 1.2 ms is caused by the reflection of theprimary pulse from the load cell up to the top of the drill rod (or anvil) and back. Note thatthe cross-sectional area of the load cell is about twice that of the NW or AW rod. Thereflection here again results in the separation of the force and velocity. The third velocitypeak at 1.85 ms is the tensile reflection of the impact compression wave from the sampler.As expected, the tension force cutoff also occurs at this time. Reflection of the return wavefrom the top of the rods is indicated by the fourth velocity peak at 2.65 ms and the fifthvelocity peak at about 3.8 ms corresponds to the second cycle return wave from the sampler.43160 —/ Force- , ‘----v*EA/c120— i: i— I • f••‘ /‘J\I , i I‘, ‘I / .C-)—‘ /180—/A1‘ I 1, •/40> I= ..k’v-v2L/c 145 m- EA/c 323 kN—4—0— I I I I I I I0.0 2.5 5.0 7.5300 -En (FEn F2j200>-0bJz 100 - - - - - - - - -LU0— I I I I I I I I I0.0 2.5 5.0 75TIME (ms)Fig. 4.4 Force, velocity and energies for SPT blow 1 at 1.5 m depth,McDonald’s Farm (after Sy and Campanella, 1991a)44The bottom plot in Fig. 4.4 compares the energy traces calculated using the force-velocity integration method in Eq. [3.4] and the force integration method in Eq. [3.7]. Forthis blow, the ENTHRU is 200 3 using Eq. [3.4] and the calculated energy at the tensioncutoff point is 160 3 using Eq. [3.7]. These energy values correspond to 42 and 34%,respectively, of the theoretical free-fall hammer energy. The discrepancy between the twovalues is a result of the non-proportional force and velocity waveforms caused by wavereflections in the SPT system and by the soil resistance acting on the sampler. Note that themaximum energy transfer occurs at 1.85 ms when the tensile reflection from the samplerreaches the transducer location in the drill rods.Figure 4.5 shows the force, acceleration, velocity and energy time histories for the28th blow at 9.1 m depth in which the recorded N value was 21. The visually observedsampler penetration for this blow is 13 mm. The recorded peak force is 89 kN and themaximum acceleration is 2000 g. The peak velocity at impact is 3.4 m/s, and the velocityis practically zero at the end of the 20 ms record. Finally, the maximum energy at thetransducer location is 285 J or 60% of the theoretical free-fall hammer energy.The upper plot in Fig. 4.6 shows the F and VEA/c traces for the same blow at 9.1 m.The force and velocity traces are again not proportional within the first compression pulsedue to reflections from the different impedances in the SPT rod system. The tensilereflection of the first compression pulse from the sampler occurs at 5.0 ms. The reflectedvelocity peak at this time is much smaller (compared to that at 1.5 m), indicative of thelarger soil resistance encountered at the sampler. There are velocity pealcs appearingregularly at about 0.7 ms interval which corresponds to the time it takes for the wave to45TIME (ms)Fig. 4.5 Measured force, acceleration, velocity and energy traces for SPT blow 28at 9.1 m depth, McDonald’s Farm (after Sy and Campanella, 1991b)46120—80 —40 —0 V VI I—200010000—1000—2000zLUC)0LLz00:::LU-JLUC)C)(I)C)0-JLU>>.-C)0:::LUzLU4.03.0 —2.0 —1.0 —0.0—1.0400300 —200 —100—0- I I I I I I I I I I I I I I I I I I0 5 10 15 20120—Force- ‘‘a ----v*EA/c- ‘II ,‘j\- I,C) -‘80 =-/—,‘,,,,%,°—“I-i L> - ILi- = 32.3 kN/m/s- 2L/c = 4.42 ms—40— I I I I I I I I I I I I I0.0 2.5 5.0 7.5 10.0400 —300 —-)>-O 200ciUzUJEn F230.0 2.5 5.0 7.5 10.0TIME (ms)Fig. 4.6 Force, velocity and energies for SPT blow 28 at 9.1 m depth,McDonald’s Farm (after Sy and Campanella, 1991a)47travel from the load cell to the top of the rods (anvil) and back. These reflections are causedprimarily by the presence of the load cell in the SPT rod system.As shown in the bottom plot of Fig. 4.6, the calculated energies are 285 J using theforce-velocity method and 256 J using the force method, corresponding to 60 and 54%energy ratios, respectively. Again, the discrepancy is due mainly to the non-proportionalforce and velocity waveforms caused by wave reflections in the system.The above wave traces illustrate that the SPT is, in some ways, a more complexdynamic system than pile driving. This is not surprising since from the point of hammerimpact on the anvil in a typical safety hammer system (Fig. 4.2), the stress wave travelsthrough a hammer guide rod, drill rods, sampler and couplings or adaptors connecting thedifferent parts, all of which can have different cross-sectional areas or impedances. Whena stress wave encounters a sudden change in cross-sectional area, part of the wave isreflected back from the interface and part is transmitted. The sign of the reflected wavedepends on the sign of the initial wave and whether or not the area is increased or decreased.Thus the different areas in the SPT drill rod system cause various wave reflections in thesystem. The hammer/anvil geometries and soil resistances also affect the stress wavepropagating in the drill rods. Therefore, the theoretical force-velocity proportionalityrelationship may not hold, and both force and velocity measurements are needed to fullycharacterize the stress waves in the SPT system. The force integration gives onlyapproximate transferred energy values depending on the complexity of the drill rod system.The above phenomena are confirmed by wave equation analysis of the SPT as discussedbelow (also in Sy and Campanella, 1991b).484.3 WAVE EQUATION ANALYSISThe one-dimensional wave equation model commonly employed in pile drivinganalysis has been used by several researchers to investigate the SPT energy dynamics andsampling process. Early wave equation analyses of the SPT by Adam (1971) and McLeanet al. (1975) were concentrated mainly on studying the effects on N-value of factors such asheight of hammer drop, anvil size, rod type and length, slack (tension gap) at rod joints andsoil resistance. It was found that the height of drop, or hammer energy, and soil resistancewere the major factors influencing N-values. However, no experimental or field verificationwas presented.The University of Florida group under Schmertmann also conducted wave equationstudies to simulate the dynamics of the SPT (Gallet, 1976; Hanskat, 1978). They were ableto obtain reasonable match of the computed results to their measured force-time data in thedrill rods, transferred energy in the rods, and sampler penetration. Their wave equationstudies indicated negligible effect on the SPT blow count of the type of rods (A or N type),type of hammers (donut or safety), rod whipping, damping losses in rods and tightness ofrod joints. Since the driving of the SPT is analogous to the driving of a pile, they suggestedthe use of the SPT and wave equation modelling to estimate the soil damping coefficients forwave equation analysis of piles.Bosscher and Showers (1987) used a wave equation program to model the SPT tostudy the effect of soil type on impact energy in the drill rods. Wave equation modellingof the SPT has also recently been used to predict bearing capacity of soil layers (Elistein,1988), to back calculate soil parameters (Goble and Aboumatar, 1992), and to investigaterod length effect on energy transfer in the SPT (Morgano and Liang, 1992).49Clearly, the wave equation model has the potential for analyzing the SPT and toprovide more insight into the mechanics of impact wave propagation in the SPT.Accordingly, a wave equation analysis was performed as part of this study to evaluate thewave equation model for prediction of the SPT sampler penetration, and to compute forceand velocity waveforms in the drill rods for comparison with the stress wave measurements.The GRLWEAP program developed by Goble Rausche Likins and Associates, Inc.of Cleveland, Ohio and based on the Smith (1960) wave equation model for pile drivinganalysis was used. The program models the three major components of the pile drivingproblem: driving system, pile and soil, as shown in Fig. 4.7. The driving system (i.e. drophammer and anvil in this SPT study) and pile (or drill rods) are represented by a series ofmasses, springs and dashpots. The soil is represented by a series of elastic-plastic springsand linear dashpots attached to the pile mass elements. The two SPT blows discussed above,Blow 1 at 1.5 m depth and Blow 28 at 9.1 m depth, were analyzed.In the analysis, the safety hammer was modelled as a 1.3 m thick element. The anvilwas modelled as a “helmet” mass and a “hammer cushion” spring. The hammer guide rod,drill rods, load cell, sampler and couplings or adaptors were also modelled as discreteelements with appropriate weights, lengths and cross-sectional areas. Because of the unitsand dimensions embedded in the GRLWEAP program, rod elements smaller than 150 mmwere not practical due to the very small numbers involved and the possibility of roundofferrors in the computations. Consequently, a minimum element size of 150 mm was used.This placed some limitations in accurately modelling the adaptors, couplings and load cell,and consequently, average areas over reasonable segment lengths were used for theseelements.50(A) Actual System Diesel (B) Model(C) Soil Model• RamFig. 4.7 Wave equation model for pile driving analysisAir? SteamAnvilCapblockHelmet‘Cushion - —Pile Soila)ESa)Cd)> a)a)0Ca)—U)Displacement51For consistency, the same hammer-anvil-drill rod model parameters were used forthe two SPT blows analyzed, except for the difference in the drill rod length. A very smallhammer damping was assigned in the analysis and a nominal rod damping as recommendedin the GRLWEAP manual for steel pile was used. For the soil model, conventional Smithdamping coefficients and quake values also as recommended in the GRLWEAP manual wereselected. The static soil resistance acting on the sampler was another input parameter in thewave equation analysis. The soil resistances on the sampler tip and sides were estimatedfrom CPT tip resistance and sleeve friction data following the procedure proposed bySchmertmann (1979). The estimated total resistances were 0.9 kN for the SPT blow at1.5 m with a sampler embedment of 200 mm, and 12.2 kN for the blow at 9.1 m with asampler embedment of 445 mm.The wave equation analysis also requires the input of hammer efficiency which isused to calculate an initial impact velocity to start off the finite difference computation.Hammer efficiency values were selected so that the computed energy values at the transducerlocation (ENTHRU) are similar to those measured in the field. Consequently, hammerefficiencies of 60% for the blow at 1.5 m and 70% for the blow at 9.1 m were needed tomatch the measured energies in the drill rods. These values are within the range commonlymeasured for safety hammers (Kovacs and Salomone, 1982).A parametric study was conducted to investigate the influence of various parametersincluding hammer length, hammer, rod and soil damping values, drill rod couplings, “tensionslack” at loose rod joints, analysis time step, rod element size and soil resistances. It wasfound that the most significant input parameters affecting the computed waveforms were theimpedances of the system above the load cell level, including the hammer itself, and the52damping values for the hammer, rod and soil elements. These factors, however, did notsignificantly affect the calculated sampler penetration (blow count) and ENTHRU. Theseresults were more sensitive to the input soil resistance and hammer efficiency values.Similar conclusion was also found in wave equation studies by previous investigators (e.g.McLean et al. 1975).Figure 4.8 shows the measured and computed force (F) and velocity (VEA/c) tracesfor Blow 1 at 1.5 m depth. Overall, the computed traces map out the trend of the measuredwaveforms. The computed impact force and velocity values at 0.3 ms are also similar to themeasured values. In the first compression pulse, however, there is an additional third smallspike in the computed traces that is not evident in the field data. The tension cutoff occursat the same time (1.85 ms) in both the measured and computed force traces. The computedvelocity profile, after arrival of the tensile reflected wave from the sampler, shows the samelarge peaks as in the measured waveform. The measured force trace beyond 2 ms and thevelocity trace beyond 4 ms are much more damped than the corresponding computed traces.Introducing slack at rod joints or increasing the hammer, rod or soil damping values in thewave equation analysis would improve the match in this portion of the waveform. However,these refinements could not be consistently applied to the other blow analyzed and are,therefore, not shown here.With an input hammer efficiency of 60%, the computed ENTHRU at the transducerlocation for the 1.5 m blow is 203 J, corresponding to an energy ratio of 43% of thepotential energy of the SPT hammer. The computed sampler penetration, or inverse of theblow count, is 130 mm, compared to the field observed value of 200 mm. This suggests thatthe ultimate soil resistance acting on the sampler in the field was less than the 0.9 kN53160—I IMEASURED I’ Force/ ‘-——— V*EA/C120— IIzI.2 i—. /I I \ / I/ I’ I80 — ‘I,C-) : \40->U: -,0—w._I-.J—1.0— I I I I I I I I I I0.0 2.5 5.0 7.51 60 —- COMPUTED Force-I“——— V*EA/c120— I ‘ / I’, i’,““. I— III‘ I ,\80 — I, —C) -2,LU 40—>U0——40—0.0 2.5 5.0 7.5TIME (ms)Fig. 4.8 Measured and computed force and velocity traces for SPT blow 1 at1.5 m depth, McDonald’s Farm (after Sy and Campanella, 1991b)54estimated from CPT data. This is not surprising since the first blow in a SPT is often insoils previously disturbed by the drilling action, and hence, the requirement for an initial“seating” drive of 150 mm before counting the blows for the next 300 mm penetration toobtain the N-value.Figure 4.9 shows the computed F and VEA/c traces for Blow 28 at 9.1 m depth.Again overall, the computed traces follow the general trend of the measured waveforms,although the computed profiles display sharper oscillations. Increasing the hammer or piledamping in the wave equation model would damp out these oscillations, improving the forcematch but not the velocity. Again, these refinements were not considered consistent. Withinthe first compression pulse, the computed velocity trace has about the same number andfrequency of peaks as in the measured trace. The computed tension cutoff at 4.7 ms is closeto the measured value at 5.0 ms. For an input hammer efficiency of 70%, the calculatedENTHRU at the transducer location is 285 3 or an energy ratio of 60%. The calculatedpenetration of 13 mm is similar to the field observed value for this blow.In summary, the one-dimensional wave equation model of the SPT gives results ingood agreement with the measured blow count or sampler penetration, provided appropriatesoil resistance and hammer efficiency values are input. The limited study conducted for thesafety hammer indicates that the main features in the measured stress waves can bereasonably simulated in the computer analysis, using small segment lengths and appropriatecross-sectional areas to model the drill rod and sampler system, and using conventional soilparameters.55160 —- MEASURED Force-----V*EA/C120 —z :,80 —() ,(.f%g’’r %40-•‘>IL -—1—0— I I I I I I I I I I I I I I I I I I0.0 2.5 5.0 7.5 10.0 12.5 15.0160 —- COMPUTED Force----V*EA/c120-Thz -80 —C)LiJ 4Q—40>U:0———0.0 2.5 5.0 7.5 10.0 125 15.0TIME (ms)Fig. 4.9 Measured and computed force and velocity traces for SPT blow 28 at9.1 m depth, McDonald’s Farm (after Sy and Campanella, 1991b)564.4 RESULTS OF DYNAMIC MEASUREMENTS AT MCDONALD’S FARMThe results of the dynamic measurements at McDonald’s Farm are summarized inTable 4.1 which lists the measured peak force, the energies calculated by the two methods,and the limit of integration used in the force method. As shown, the energy ratios (ER) bythe force integration (F2) method are generally within 10 to 15% of the corresponding valuesfrom the more fundamental force-velocity integration (FV) method.Table 4.1 Summary of SPT energy measurements at McDonald’s FarmSPT SPT Peak FV Method F2 Method F2 IntegDepth Blow Force ER ER Limit, At(m) No. (kN) (%) (%) (ms)1.5 1 86 42 36 1.843 86 42 40 1.833.0 1 89 45 43 2.317 92 45 44 2.314.6 1 83 52 37 3.244 86 49 49 3.006 86 36 41 2.986.1 1 83 65 46 3.707 94 57 55 3.7414 82 43 42 3.677.6 1 86 59 47 4.645 86 50 46 4.619.1 1 86 57 52 4.976 92 62 57 4.8610 86 50 50 5.1128 93 60 57 4.97The energy ratios calculated by the two methods, as well as the measured peak force,are plotted against depth in Fig. 4.10. Note the slight trend of increasing energy with depth,57FV METHOD F2 METHODENERGY RATIO (%) ENERGY RATIO (x) PEAK FORCE (kN)0 25 50 75 100 0 25 50 75 100 0 50 100 150o...iiiiIiiiiIiiiiIiitt — iiiiliii;Iiiiiliiii —_____________________02—0 iiu—‘ 4—E :- 0 OD DODI 5—I— ---6= 0 00 DOD •7—00 ml8—9 ODD anc10— -____________________—Fig. 4.10 Calculated energy ratios and measured peak force vs depth,McDonald’s Farm58by either method. This is due to the effect of the short rod length in the SPT. AsSchmertmann and Palacios (1979) indicated, at shallow depth or with short rod length, thereis insufficient time for the hammer to transfer all of its energy to the drill rod before returnof the tension wave from the sampler which effectively cuts off further energy transfer fromhammer to rod. The peak force, however, is almost constant with depth, with an averagevalue of about 90 kN. This is not surprising, since the initial portion of the force trace upto the force peak should not be affected by reflections in the rods or from the soil at thesampler. In fact, as shown in the following paragraphs, the peak force in the SPT istheoretically a function only of the hammer drop or impact characteristics.As discussed in Chapter 3, wave mechanics theory indicates that for an impact wavetravelling in one direction, the force (F) and particle velocity (V) at any point in a uniformrod are proportional, i.e.[4.1] F(t) = V(t)where EA/c is the impedance of the rod. Consequently, the peak force near the top of theSPT rods will be proportional to the peak particle velocity.The peak particle velocity, on the other hand, is directly related to the hammer impactvelocity (V1) through[4.2] V = 1 V.1÷a59where a is the hammer to rod impedance or area ratio. Eq. [4.2] is obtained byconsideration of force equilibrium and velocity compatibility across the plane of contact whena cylindrical hammer strikes a bar of similar material (Fairhurst, 1961).Then, from conservation of potential energy and kinetic energy during hammer fall,the impact velocity is related to the square root of the hammer stroke or drop height by[4.3]= J2ghewhere g is the gravitational acceleration, h is the hammer drop height and is an energy lossfactor during hammer fall. The above relationships, therefore, suggest that for a given SPTsystem with constant energy loss, the peak force is proportional to the square root of thehammer drop height. If the drop height is constant (i.e. 0.76 m in the SPT), the peak forceat the top of the drill rods will be constant, regardless of the length of the rods or soilconditions. The peak force data shown in Fig. 4.10 thus confirm the above theoreticalconcepts. In fact, the consistency of peak force can be used to check the quality of the SPTforce measurement as demonstrated in Sy and Campanella (1993a).4.5 SIGNIFICANCE OF SPT ENERGY CORRECTION FACTORSAs discussed in Chapter 2, the current ASTM D4633-86 and ISSMFE (1988) testprocedures both specify three K factors to correct the energy calculated by the forceintegration method, i.e.60[4.41 E = cK1K2 f[F(t)]2 dtwhere K1 is the load cell location correction factor, K2 is the short rod length correctionfactor, and K is the wave speed correction factor. The first two are theoretical correctionfactors so that the corrected energy, E1, refers to that at the top of an ideal infinite rod. Thethree correction factors are examined here in the light of the SPT dynamic measurementsfrom McDonald’s Farm.Table 4.2 lists the applicable ASTM K1 and K2 factors for the drill rod configurationused in each SPT, as well as the measured rod length from the load cell to sampler tip (L’)and the theoretical wave return time (2L’/c where c = 5120 mIs). For the safety hammerused in this study, the rod length between the point of impact (or anvil) and the load celllocation was 1.9 m for all tests. As shown in Table 4.2, the combined effect of K1 and K2is small below about 6 m depth.Table 4.2 K1 and K2 correction factors and theoretical 2L’lcDepth ASTM K1 ASTM K2 L’ 2L’Ic(m) (m) (ms)1.5 1.17 1.15 3.71 1.453.0 1.07 1.08 5.23 2.044.6 1.04 1.04 6.76 2.646.1 1.03 1.03 8.28 3.237.6 1.01 1.01 10.41 4.079.1 1.00 1.01 11.33 4.4261Figure 4.11 shows the calculated energy ratios by the force integration approach withand without application of the K1 and K2 factors, as well as the measured compression pulsetime duration (st) used as limit in the force integration. As shown, the use of the theoreticalcorrection factors (K1 and K2) appears to “straighten out” the original trend of increasingenergy with depth, suggesting a constant energy ratio of about 50%. The results, however,are not statistically conclusive since only two to four blows were measured at each depth.Furthermore, a more appropriate verification of these K-factors would require that the heightof drop or the kinetic energy at impact be measured accurately for each hammer blow, whichwas not done in this study. A recent study by Morgano and Liang (1992), however,provides another interesting perspective on the theoretical K2 factor, as discussed below.Morgano and Liang (1992) recently investigated the effect of rod length on the energytransfer in the SPT. They conducted wave equation analyses as well as field experimentsfor different SPT rod lengths. In their field testing, they measured force and accelerationnear the top of the drill rods to determine the transferred energy using Eq. [3.4]. They alsomeasured the hammer velocity just before impact with a radar in order to calculate thehammer kinetic energy at impact. The measurement of the hammer impact velocity takescare of the inherently variable hammer drop height obtained with the rope and catheadtechnique used in the SPT. The ratio of the maximum transferred energy to the hammerkinetic energy is a measure of the energy transfer efficiency of the system. Both theirnumerical and field studies show that for short rod lengths, significant energy can still betransferred to the rods beyond 2L’Ic due to secondary or subsequent hammer impacts. Theirstudies confirm that transferred energy (or the energy transfer efficiency) increases withincreasing rod length, up to about 15 m, but it also depends on the soil resistance. Based62F2 MEFHOD F2 METHODENERGY RATIO (%) ENERGY RATIO*K1*K (%) LIMIT OF F2 INTEG (ms)0 25 50 75 100 0 25 50 75 100 0 2 4_iiiiIiiiiIiiiiIiii— iiiiliiiilitiiliiii— 1111 I 11111 I2—-.-.‘ 4—E :- DOD5—I— --U -O 6—7—-— THEORETICAL i8= 2L/caDD —. I.—10— -____________________-___________________Fig. 4.11 Energy ratios calculated by force integration method with and withoutcorrection factors, McDonald’s Farm63on field measurements at several sites, they propose an average transfer efficiency correctioncurve (i.e. a measure of K2) for the effect of short rod length.Figure 4.12 compares the theoretical K2 correction factors from ASTM D4633-86 andISSMFE (1988) with those proposed by Morgano and Liang (1992) based on fieldmeasurements. As expected, the field-derived factors are less than the theoretical valuesmainly because of the additional energy transfer beyond 2L’/c in short rod lengths. Thiscomparison suggests that the theoretical K2 factors in ASTM D4633-86 and ISSMFE (1988)are “upper bound” values and might only be appropriate for the force integration approach,if at all needed.The right hand plot in Fig. 4.11 compares the measured compression pulse duration,i.e. the limit of force integration, with the theoretical wave return time (2L’/c). As shown,the compression pulse duration, measured from beginning of the force trace to the tensioncutoff point, is always longer than the theoretical return wave time. There are severalreasons for this apparent longer wave return time. As indicated in Palacios (1977), thevelocity of wave propagation in an elastic rod theoretically varies with frequency of thewave. Since the impact wave pulse actually consists of an infinite number of sinusoidalwaves of different amplitudes, each frequency wave will travel with different velocity andthe wave form will change shape as it progresses along the rod. This phenomenon is knownas dispersion, and it explains why the measured force pulse, even in an ideal uniform rod,is not a square waveform as the hammer-rod impact theory would suggest (Palacios, 1977).Furthermore, the different areas in the SPT rod system, including the joints or couplings(and especially if they are loose), cause wave reflections and dispersions which also resultin the apparent delayed wave return. The length of the initial wave rise would also depend64CORRECTION FACTOR K20.8 1.0 1.2 1.4 1.6I I I I I I I I I I I Ip5- P /c7I-____ISSMFE (1988)ASTM D4633—86O&O&S Morgano & Liong (1992)20 —_ __ ___________________________Fig. 4.12 Comparison of SPT energy correction factors, K2, for effect of shortrod length (from Sy and Campanella, 1993a)65on the actual hammer-anvil contact characteristics. Thus, the measured compression pulseduration, or the time for maximum energy transfer, is expected to be longer than thetheoretical 2L’Ic time. Consequently, there is no rational basis for use of the K correctionfactor as recommended in ASTM D4633-86 and ISSMFE (1988) to reduce the calculatedenergy by the force integration method. The K factor, as Riggs et al. (1984) pointed out,effectively “compresses” the time scale of the measured force trace. Similarly, there is alsono justification in simply cutting off the energy transfer beyond the theoretical 2L’/c asClayton (1990) did in the force integration method, even though the energy contributionbeyond this time is, for all practical purposes, insignificant. Thus if the force method isused, the integration should be carried out to the time of arrival of the tensile reflection fromthe sampler, which is usually longer than the theoretical 2L’Ic.As indicated above, there has been considerable confusion on the application of thethree correction factors, and on the meaning and use of the corrected energy (F1) as specifiedin ASTM D4633-86 and ISSMFE (1988). Considering the assumptions and limitations ofthe force integration approach, and reliability of current dynamic measurements, the effectsof K1 and K2 are relatively small. In addition, the use of the K factor is fundamentallyunsound. It is, therefore, recommended that the calculated transferred energy in the SPTbe reported without the use of the three correction factors. The calculated energy, E, wouldthen refer to the actual energy entering the rod, not to an infinite rod condition.4.6 LIMITATIONS OF SPT ENERGY MEASUREMENTSThere are several assumptions or limitations in the use of the current force integrationmethod (Eq. [4.4]) for SPT energy determination which should be recognized. Eq. [4.4]66assumes that the energy transferred into the rods is contained only within the firstcompression pulse with a duration of approximately 2L’/c. For relatively long rods, thisassumption of energy cutoff at 2L’/c is not bad. For rod lengths less than about 15 m,however, wave equation analyses and field measurements by Morgano and Liang (1992)indicate that significant energy transfer can still occur beyond 2L’/c, particularly in very softsoils.Eq. [4.4] further requires input of one cross-sectional area for the whole rod/samplersystem below the anvil, which is difficult for a non-uniform system consisting of rods ofvariable cross-sectional areas or rods with enlarged ends or couplings. More importantly inEq. [4.4] is the inherent assumption that the force and particle velocity at the measurementpoint are proportional within the first compression pulse, which would be true for wavepropagation in an ideal, elastic rod of uniform cross-section with no external side resistances.As discussed above, this assumption does not hold for a typical safety hammer systemconsisting of the hammer guide rod, drill rods and sampler connected by couplings andadaptors, all of which can have different cross-sectional areas. Changes in rod cross-sectionscause wave reflections which violate the force/velocity proportionality assumption implicitin Eq. [4.4].The alternative and more rational approach is by measuring force and accelerationnear the top of the drill rods and determining the transferred energy by time integration offorce times velocity (Eq. [3.4]). The maximum transferred energy, ENTHRU, representsthat part of the hammer energy available to do work on the drill rods and sampler. Thisforce-velocity integration approach avoids the shortcomings in the existing force integrationmethod. Also, the force and velocity traces can be displayed for every blow in the field and67the principle of force/velocity proportionality can be used as a check on the reliability of thedynamic measurements, similar to current procedure in dynamic monitoring of pile driving.There were, however, some problems associated with velocity determination from thepiezoelectric accelerometers used in this study. Some velocity traces did not return to zeroat the end of the hammer impact. These drifting problems due to integration, however,occurred mostly beyond about 4L’/c, an area of little practical significance for energytransfer calculation. Recent research at the University of Colorado, Boulder (Goble andAboumatar, 1992) suggests that some modern piezoresistive accelerometers can produce goodquality and stable measurements for steel-to-steel impact.Despite its limitations, the force integration method is still sufficiently useful for mostSPT applications where the drill rods are not very short and do not contain significant cross-sectional area changes. The consistency of the peak force, regardless of depth or N-value,can provide some check on the quality of the force measurement. The three ASTMcorrection factors, K1, K2 and K, should not be used in calculating the energy transfer bythe force integration approach.68CHAPTER 5DYNAMIC MEASUREMENTS AN]) ANALYSIS OF BPT5.1 PROPOSED ENERGY APPROACH FOR NORMALIZING BPT BLOW COUNTSAs discussed in Chapter 2, the Becker hammer, like all diesel hammers, givesvariable energy output depending on combustion condition and soil resistance. Neglectingthis variable hammer energy is one reason why many of the previous BPT-SPT correlationsdo not work. To overcome this problem, Harder and Seed (1986) proposed a method ofusing the peak bounce-chamber pressure to correct the BPT blow counts to a reference“constant full combustion condition”. Their bounce-chamber pressure correction method,however, could not account for energy losses in the driving system (helmet, cushion, spout,etc.) below the anvil, and consequently, it could not be consistently applied to differentBecker rigs or hammers.Experiences from piling have shown that it is the energy actually transferred into thepile, not the potential or kinetic energy of the hammer, that directly affects the drivingresistance or penetration of the pile. The importance of the transferred energy is alsorecognized in the SPT. Thus for liquefaction analysis, for example, the measured SPT Nvalues are routinely corrected to a reference energy level of 60% of the theoretical free-fallSPT hammer energy, using[5.1] N =N—60 6069where N is the N-value corrected to 60% reference energy level, N is the measured SPTN-value, and ER is the measured energy ratio in percent. A similar approach fornormalizing the measured BPT blow count to a reference energy level is proposed asfollows.It is proposed that a transferred energy of 30% of the manufacturer’s rated energyof 11.0 kJ for the ICE 180 hammer be adopted as a reference energy level for the BPT, andthat the measured blow counts be corrected using:[5.2] N = N ENTHRUb30 bwhere Nb30 is the blow count corrected to ENTHRU of 30% (or 3.30 kJ), Nb is the measuredBPT blow count, and ENTHRU is the measured maximum transferred energy expressed aspercent of the rated hammer energy of 11.0 kJ. The ENTHRU of 30% represents theaverage of several Becker rigs measured to date, including both HAV 180 and AP1000 typerigs driving 140 mm and 170 mm size pipes. The 30% average transferred energy in theBPT is close to the mean efficiency value observed for other double-acting diesel hammersdriving steel piles as compiled in Rausche et al. (1985a).The energy correction based on Eq. [5.2] is simple, and because ENTHRU is anabsolute and measurable quantity, the corrected blow count, Nb30, has a physical meaning.Dynamic measurements of several BPTs are presented in this chapter, and both the Harderand Seed’s approach based on bounce-chamber data and the proposed energy approach basedon ENTHRU data are evaluated.705.2 DYNAMIC FIELD MEASUREMENTSDynamic measurements of the Becker hammer drill and penetration tests wereperformed as follows. Representative time histories of combustion-chamber and bounce-chamber pressures were measured on the Becker hammer (ICE 180) to evaluate the dieselhammer performance. These measurements were carried out simultaneously using pressuretransducers connected to a high-speed data acquisition system. In addition, peak bounce-chamber pressure for every blow during the BPT was automatically measured with anotherpressure transducer at the end of a 15 m long hose connected to a computer-based dataacquisition system. The Becker casing was also instrumented with strain transducers andaccelerometers at 0.4 m below the top of the pipe and monitored using the Pile DrivingAnalyzer (Goble et al. 1980). The Pile Driving Analyzer (PDA) measures strain (todetermine force) and acceleration for each hammer blow, integrates the acceleration timehistory to obtain velocity, and computes quantities of interest including peak force, peakvelocity and ENTHRU. The transferred energy is calculated by time integration of forcetimes velocity. The PDA force and velocity time histories are displayed in the field forevery blow. This again allows a check on the reliability of the measured data by inspectionof the force/velocity proportionality.Figure 5.1 shows typical time histories of bounce-chamber pressure, combustionchamber pressure, and force near the top of the drill pipe for three consecutive Beckerhammer blows. The bounce-chamber pressure time history is essentially a sine wave witha period of approximately 0.63 s. The combustion pressure and force time histories showthat one hammer impact event lasts only about 20 ms. Ram impact is characterized by peakforce, and as expected, it occurs when the bounce-chamber pressure is at its trough and when71QaaC-)0aC)C)600z0Li..CaaC)060TIME (s)800400170 180TIME (ms)zwC-)0Fig. 5.1 Bounce-chamber pressure (BCP), combustion-chamber pressure (CCP)and force (FOR) time histories for three consecutive Becker hammerblows, including an expanded view of one blow at bottom (from Sy andCampanella, 1992b)72the combustion pressure is at its peak. A close-up view (50 ms window at the bottom ofFig. 5.1) of the combustion pressure and force traces reveals that, in fact, the peakcombustion pressure of 6.5 MPa occurs about 2 ms before impact and the maximum pressureis maintained for a duration of about 8 to 10 ms. This preignition is a particular feature ofatomized fuel-injection diesel hammers.The initial BPT research was conducted during January and February, 1991 at thenew Kwantlen College campus in Richmond, in which a series of BPTs, SPTs and CPTswere performed in a controlled pattern. Figure 5.2 shows data from a CPT. The site isunderlain by 25 m of fine to medium grained sands overlying interbedded sand and siltdeposits. The upper sand deposits are generally clean, except for a few silty layers asindicated in Fig. 5.2. The top 10 m of the soil profile was densified by dynamic compactionprior to the field testing program (Naesgaard et al. 1992).As part of the testing program at the Richmond test site, four BPTs were conductedusing two different drill rigs (HAV18O and AP1000 types) and two different pipe sizes(140 mm and 170 mm), and also with variable combustion conditions (maximum versusreduced fuel settings). Table 5.1 summarizes the main characteristics of the four BPTs. Theeffects of the various factors on the Becker blow counts can be investigated by comparingappropriate pairs of BPT data. BPT3 and BPT4 allow an evaluation of variable combustionconditions, BPT2 and BPT5 allow an assessment of different rigs or hammer conditions (butthe same ICE 180 hammer model), and BPT3 and BPT5 consider the effect of different pipesizes. Comparisons of these BPT data from the Richmond test site are discussed in theremaining part of this chapter.73Fig. 5.2 Cone penetration test data, Richmond test site(from Sy and Campanella, 1992b)7401020U,a)C4-,0)=I—awCONE BEARING STRESS SLEEVE FRICTION FRICTION RATIO BEHIND TIP pp INTERPRETEDQt (bar) Fs (bar) Qt/Fs=Rf (%) U2(m.of water) PROFILE250 0 2 0 2.5 —5 45Ic o_aI SAND10 10 10 10I SAND20 20 20 20IclayeyI SILT30 30 30’’ 30TABLE 5.1 Characteristics of BPTs at Richmond test siteBPT Max. Fuel Casing Inner Becker DrillNo. Depth Setting O.D. Pipe Type - Rig No.(m) (mm) Type2 24.1 Full 140 Fixed HAV18O - Fl3 24.1 Full 170 Floating AP1000 - 1074 8.8 Reduced 170 Floating AP1000 - 1075 28.0 Full 140 Floating AP1000 - 1075.3 MEASURED STRESS WAVESFigure 5.3 shows the stress wave measurements from BPT3 (full throttle) for twohammer blows, one at shallow depth in soft driving condition and the other at depth inharder driving condition. The wave traces shown are the force (F), velocity normalized bythe pipe impedance (VEAIc), and the calculated energy by integration of the force timesvelocity. For the 170 mm O.D. pipe used, EA/c = 313.4 kN/m/s. The upper plot in Fig.5.3 is for a blow at 2.5 m depth with a driving resistance of 19 blows/300 mm and a totalpipe length of 3.9 m, whereas the lower plot is for a blow at 20.0 m with a blow count of53 and a pipe length during driving of 22.2 m. As shown in the upper plot, the shorter pipein easy driving behaves somewhat like a rigid body or a ‘stout” pile. This is illustrated bythe velocity trace showing the pipe moving down as one unit over a relatively long timeperiod, while the stress wave (force trace) propagates down and up the pipe for severalcycles after impact. In the lower plot, the wave traces for the longer pipe showcharacteristics typical of the driving of a long slender pile. The precompression phase afterhammer port closure is recorded in the first 10 ms of the traces, with impact occurring at75z—250 I I I I I I I I I I I I I I I I I I I I I I I I I0 5 10 15 20 25 30 35 40>-0LUzLU-)>-0uJzU10007505002500A: 2L/c=1.4ms DEPTH=2.5m Force: EA/c=313kN/m/s ---- V*EA/c= —— Energy —3——— /—2: ,‘E”%%:‘A1000750z500250—250TIME (ms)Fig. 5.3 Wave traces at 2.5 m and 10.0 m in BPT3, Richmond test site(from Sy and Campanella, 1992a)0 5 10 15 20 25 30 35 407610.5 ms and the subsequent compression wave propagating down and returning up the pipein the next 8.5 ms. The tensile (negative force and positive velocity) toe reflection iscaptured at 19 ms in the record, followed by the return wave reflecting from the top of thepipe and going down the pipe a second time with much reduced amplitude. The separationof the force (increase) and velocity (decrease) traces between 12 ms and 19 ms suggestssubstantial shaft friction acting on the 20 m embedded pipe. As expected, the peak force of292 kN for the softer blow at 2.5 m is much lower than the measured 797 kN peak force forthe harder blow at 20 m. The maximum transferred energies, however, are not significantlydifferent, being 2.72 kJ for the softer blow and 2.82 kJ for the harder blow, correspondingto 24.7 and 25.6%, respectively, of the manufacturer’s rated energy for the hammer.5.4 VARIABLE COMBUSTION CONDITIONSThe difference between BPT3 and BPT4 is the combustion condition. BPT3 wasperformed with the maximum fuel or throttle setting (i.e. full combustion condition), whereasin BPT4, the throttle was reduced and varied several times during the test to achieve variouscombustion conditions. Both BPT3 and BPT4 were conducted with rig 107 (AP1000 type)using 170-mm diameter floating pipes. A total of 3249 blows was recorded for BPT3 and1012 blows for BPT4. The results of the dynamic measurements for BPT3 (full throttle) andBPT4 (reduced throttle) are summarized in Fig. 5.4, which shows the measured blow count(Nb), peak bounce-chamber (BC) pressure, peak force and maximum transferred energy(ENTHRU) plotted against depth. The latter three quantities are average values for each0.3 m of pipe penetration. The ENTHRU value is shown as a percentage of themanufacturer’s rated energy of 11.0 kJ for the ICE 180 hammer. As expected, the blow77Nb (blows/O.3 m) B.C. PRESSURE (kPa) PEAK FORCE (kN) ENTHRU (%)o 40 80 50 100 150 0 500 1000 10 20 30 40— iilitil — iiiiliiii — iitiliiii —________________-—t- _—‘_::..- \::----- _7-’ c\—- c c-.- )10——SE -5—=I— -0LLI -20—25— BPT3: Full ThrottleBPT4: Red. ThrottleFig. 5.4 Blow count (Nb), bounce-chamber (BC) pressure, peak force andENTHRU vs depth for BPT3 and BPT4, Richmond(from Sy and Campanella, 1992b)78counts for reduced-throttle or reduced-fuel condition (BPT4) are higher than those for thefull throttle condition (BPT3), whereas the bounce-chamber pressures, peak forces andENTHRU values are lower.For full throttle condition (BPT3), the blow count generally increases with depth.Similarly, the bounce-chamber pressure and peak force also increase with depth, or withincreasing driving resistance. The maximum transferred energy, however, is surprisinglyconstant with depth, at about 27%. This observation suggests that even though the hammerwas apparently delivering more kinetic energy (i.e. higher bounce-chamber pressure orhigher peak force) with increasing depth or driving resistance, the maximum transferredenergy to the top of the pipe remained practically constant. This is because the increase inforce with driving resistance is equally matched by a decrease in displacement, the productof which makes up the work done (or transferred energy) on the Becker pipe.Figure 5.5 shows the bounce-chamber pressure and ENTHRU data for the first 8.8 mdepth from BPT3 and BPT4 plotted against the measured blow count (Nb). As expected, thereduced combustion (BPT4) data points lie above and to the left of the full combustion(BPT3) data points in both graphs, since blow count increases and bounce-chamber pressuredecreases with decreasing combustion efficiency or ENTHRU. For comparison, Harder andSeed’s calibration curve A-A is also shown on the bounce-chamber pressure versus Nb graph.The trend of the full combustion (BPT3) data points on this graph, as indicated by the dashedline, is to the left of and parallel to A-A line, suggesting that Harder and Seed’s calibrationline corresponds to a higher combustion efficiency, or higher ENTHRU, than that measuredin this study. This is not surprising since the A-A line was determined from a hammer withan air blower or supercharger on, which increases the combustion efficiency by increasing79100a aa aa a aa 9: a Ca a aC%a a aa• •aa ia—hIt.2r) ..d aio—Aioa a a a-0 - a-aa_-a-A..aaa SPT3: Full Throttle .a.aB BPT3: Full Throttleaaaaa BPT4: Red. Throttle aaaoa BPT4: Red. Throttle—Ilj 11111111111111 1— ltIlllIlIIllIlIllIIIlllllIllI50 75 100 125 10 20 30 40B.C. PRESSURE (kPa) ENTHRU (%)Fig. 5.5 Bounce-chamber (BC) pressure and ENTIIRU vs blow count (Nb) forBPT3 and BPT4, Richmond (from Sy and Campanella, 1992b)80the oxygen intake into the combustion chamber. The air blower, although equipped on rig107, was not used for these tests.Figure 5.6 shows the measured blow counts (Nb), the bounce-chamber pressure-corrected blow counts based on Fig. 2.6 (NbC), and the energy-corrected blow counts usingEq. [5.2] (Nb30) for BPT3 and BPT4. As shown, the two measured profiles virtually collapseinto one when the blow counts are corrected by either method. This illustrates that both thebounce-chamber pressure-correction and the energy-correction methods can adequatelyaccount for the effect of variable combustion conditions on the Becker blow counts. The NbCvalues, however, are much lower than the Nb30 values, again suggesting that the Harder andSeed’s A-A line corresponds to some combustion efficiency or energy transfer higher thanan ENTHRU of 30%.5.5 DIFFERENT DRILL RIGS OR HAMMERS CONDITIONSThe effect of different drill rigs or hammer conditions can be evaluated by comparingBPT2 and BPT5. BPT2 was carried out using rig Fl, a HAV18O type drill, while BPT5 wasconducted with rig 107, an AP1000 type drill. The same-sized pipe, 140-mm O.D., wasused, but BPT2 had fixed inner pipe and BPT5 had floating inner pipe. Both hammers wereoperated at full-throttle condition.Figure 5.7 compares the measured blow counts, bounce-chamber pressures, peakforces and ENTHRU values for the two drill rigs. The blow counts for BPT2 areconsistently lower than those in BPT5, suggesting that rig Fl (BPT2) was more efficient.This is indeed confirmed by the ENTHRU data which show values for BPT2 consistentlyhigher than those for BPT5. The bounce-chamber pressure data, however, do not show the81Nb (blows/O.3m) Nb (blows/O.3m) Nb30 (blows/O.3m)o 20 40 60 80 0 20 40 60 80 0 20 40 60 800— 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-‘‘.... ‘42-• I•;•) .. —4---- I..’ I IEi-— BPT3: Full Throttle- - -- BPT4: Red. Throttle B.C. PRESSURE—CORRECTED ENERGY—CORRECTEDl)_______________________________—______________________________—____________________________Fig. 5.6 Measured (Nb) and corrected (NbC and Nb30) blow counts vs depth forBPT3 and BPT4, Richmond (from Sy and Campanella, 1992b)82Nb (blows/O.3 m) B.C. PRESSURE (kPo) PEAK FORCE (kN) ENTHRU (%)0 25 50 50 100 150 0 500 1000 10 20 30 400_..IIIIIIII I — itiiliiii — iiiiliiii —________________-— BPT2: Rg Fl30——-—- BPT5: Rg 107Fig. 5.7 Blow count, bounce-chamber pressure, peak force and ENTIIRU vs depthfor BPT2 and BPT5, Richmond (from Sy and Campanella, 1992b)83same trend. At the same depth, the more efficient BPT2 has bounce-chamber pressurereadings lower than those for BPT5, inconsistent with the expectation that for the sameresistance, increasing combustion efficiency or increasing bounce-chamber pressure shouldbe associated with decreasing blow count (refer to the blow count correction curves in Fig.2.6).The bounce-chamber pressure and ENTHRU data are plotted against Nb in Fig. 5.8.Except for some scatter at shallow depths (i.e. at low blow counts), where the diesel hammerwas not firing continuously, two trends are evident. The ENTHRU data are practicallyindependent of blow count (or depth as shown in Fig. 5.7), being on average about 35% forBPT2 and 27% for BPT5, whereas the bounce-chamber pressure data follow a constantcombustion trend line almost parallel to A-A line. Note that for both BPT2 and BPT5, thebounce-chamber data lie on the same trend line, confirming the apparent inconsistencyindicated above. The more efficient (or higher ENTHRU) BPT2 data points are expectedto fall in the region between the BPT5 data and A-A line in the bounce-chamber pressureversus Nb graph. It is not surprising then that when BPT2 and BPT5 blow counts arecorrected to A-A line using the bounce-chamber pressure-correction method, the BPT2 (rigFl, HAV18O) NbC values are still consistently less than BPT5 (rig 107, AP1000) values, asshown in Fig. 5.9. On the other hand, the energy-corrected Nb30 profiles again practicallycollapse into one profile.Harder and Seed (1986) found similar inconsistency when comparing BPT resultsfrom a HAV18O (also known as B180) rig and an AP1000 rig. After correcting for hammercombustion efficiencies to A-A line, they found that the AP1000 N values were still 1.5841008 8Er.)810-: 8 10 - 8888 83 - 80 -3 -ABPT2: Rig Fl (HAVI8O) ••••• BPT2: Rig Fl (NAV18O)8888 BPI5: Rig 107 (AP1000) 88488 8PT5: Rig 107 (AP1000)IhuLl I Ill I 1_hhhIhjLIIIIIhIhIlLhIhhIhIhhhT50 75 100 125 150 10 20 30 40B.C. PRESSURE (kPa) ENTHRU (%)Fig. 5.8 Bounce-chamber pressure and ENTHRU vs blow count for BPT2 andBPT5, Richmond (from Sy and Campanella, 1992b)85Nb (blows/O.3m) Nb (biows/O.3m) Nb30 (blows/O.3m)o 25 50 0 25 50 0 25 50(.1— I I I I — I I I I I I I I — I I I I I I I5—- -c_I ..:‘ — —15-•— BPT2: Rig Fl (HAV18O)----- BPT5: Rig 107 (AP1000) B.C. PRESSURE—CORRECTED ENERGY—CORRECTED_____________________ _____________________—___________________Fig. 5.9 Measured and corrected blow counts vs depth for BPT2 and BPT5,Richmond (from Sy and Campanella, 1992b)86times higher than the HAV 180 values. This discrepancy suggests that the bounce-chamberpressure-correction procedure in Fig. 2.6 is not generally applicable to all Becker rigs.As mentioned earlier, bounce-chamber pressure is only an indicator of the dieselhammer performance above the anvil. When the ram strikes the anvil in the hammer, theimpact wave propagates through a striker plate/cushion/helmet system below the anvil andthen a driving cap or “spout” resting on top of the Becker pipe. Differences in the cushionmakeup and condition, and differences in spout design will affect the energy transmissionefficiency between the anvil and the top of the pipe. Such energy losses in the drivingsystem will be reflected in the measured transferred energy near the top of the pipe, but notby the bounce-chamber pressure measurements. In other words, two hammers with exactlythe same combustion condition but different energy losses through the driving systems wouldstill define the same combustion curve in the bounce-chamber pressure versus Nb plot butyield different transferred energies, as observed in the plots in Fig. 5.8. Thus the bounce-chamber pressure-correction method can not provide a consistent approach for normalizingBPT blow counts between different rigs or hammers.The Nb30 results in Fig. 5.9 again confirm that ENTHRU is a fundamental and usefulparameter for normalizing the BPT blow counts regardless of the Becker rig type, hammercondition or driving system.5.6 DIFFERENT PIPE SIZESThe effect of different pipe sizes can be investigated by comparing BPT3 and BPT5,both carried out with the same rig 107 operating at full throttle. BPT3 was conducted using87170 mm O.D. casing, whereas BPT5 used 140 mm O.D. casing, both with floating innerpipes. These two casing sizes are the most commonly used for the BPT.Fig. 5.10 compares the test results for BPT3 and BPT5. As expected, because of thelarger sized pipe, BPT3 blow counts are greater than those of BPT5. The BPT3 bounce-chamber pressures are slightly higher than BPT5 values, consistent with the fact that for thesame combustion condition, bounce-chamber pressure increases with increasing blow count.The peak force data also show higher values for BPT3 relative to BPT5. This trend is alsoexpected since higher bounce-chamber pressure implies higher equivalent hammer stroke andhence results in higher peak force. The ENTHRU values for BPT3 and BPT5 are similar,suggesting that the higher force in BPT3 is compensated by its smaller displacement (i.e.higher blow count) relative to BPT5, the product of these two quantities determining thetransferred energy in the pipe.One noticeable feature between the two blow count profiles in Fig. 5.10 is that theBPT3 profile is more “spiky” and would at first glance appear to suggest that the largerdiameter pipe is much more sensitive to soil variability than the smaller pipe (BPT5). Acomparison of corresponding Nb and ENTHRU profiles, however, indicates that the higherNb values or peaks in BPT3 are associated with relatively lower ENTHRU values, andconversely, lower Nb values with higher ENTHRU. After correction for hammer efficienciesas shown in Fig. 5.11, the dominant spikes are a bit more subdued. Thus the apparent spikyblow count profile may not necessarily imply better indication of soil density. Anothercomplicating factor is that the amount of shaft resistance on the two pipe sizes is differentand undoubtedly affects the measured blow counts.88Nb (blows/O.3m) B.C. PRESSURE (kPa) PEAK FORCE (kN) ENTHRU (x)0 40 80 50 100 150 0 500 1000 10 20 30 40I I I tiil — tiiiliiii — tiiiliiii —• .‘ ..,.I’ _.,‘•._•,. ) ‘,• S• <5 Ii --- ‘I10— ‘- -- c v--.-.---I I,—S ‘ N‘c15— Y ->:1-——)__•,• I- A20— -‘I S —, I, S I—I S IS S— S I— I • SI25—- c c..— I —S S-— BPT3: 170 mm30——--- BPT5: 140 mmFig. 5.10 Blow count, bounce-chamber pressure, peak force and ENTHRU vs depthfor BPT3 and BPT5, Richmond (from Sy and Campanella, 1992b)89Nb (blows/O.3m) Nb (blows/O.3m) Nb30 (blows/O.3m)o 20 40 60 80 0 20 40 60 80 0 20 40 60 80I — III 11111111111 I — 1111111 III I I-Th-- -- . — ‘,.“S’ —5__cf - c— I55 1 I• I_— —10— L —-I’ —S I IS II I] I- (- S ,___1—‘S -S S. S15— _——I— Is.U- • S -LiJ • -o c-S•‘I —• BPT3: 170 mm -BPT5: 140 mm B.C. PRESSURE—CORRECTED - ENERGY—CORRECTED30- -___________________—_________________Fig. 511 Measured and corrected blow counts vs depth for BPT3 and BPT5,Richmond (from Sy and Campanella, 1992b)90As expected, the bounce-chamber pressure-corrected and ENTHRU-corrected blowcounts for the larger pipe (BPT3) are consistently higher than the corresponding values forthe smaller pipe (BPT5), as shown in Fig. 5.11. The corrected blow counts are presentedin another form in Fig. 5.12 in order to establish a relationship between the two pipe sizes.Linear regression analyses of the data give the following relationships:[5.3] N (170 mm) = 1.45 NbC (140 mm)[5.4] Nb30(l7O mm) = 1.40 Nbso(l4O mm)For the same hammer and soil conditions, the blow count or driving resistance is afunction of the dynamic soil resistances (shaft and toe) acting on the pipe, the magnitude ofwhich is governed by the pipe-soil contact areas. The larger the pipe, the larger theresistance, and therefore, the higher the blow count. Theoretically, the pipe size factorbetween the 170 mm and 140 mm diameter pipes should lie between two bounds: one boundcontrolled by the ratio of the unit pipe shaft areas, i.e. 1.2, for zero toe resistance condition,and the other controlled by the ratio of the pipe toe areas, i.e. 1.5, for zero shaft resistancecondition. The pipe size factors in Eqs. [5.3] and [5.4] fall within this theoretical bound.Stewart et al. (1990) reported similar pipe size factors at two sites based on bounce-chamberpressure-corrected blow counts. Thus, Eqs. [5.3] and [5.4] will allow “conversion” of blowcounts from one size to another.91QU-E2.t})L•-V2o740Fig. 5.12 Corrected blow counts for BPT 3 vs BPT 5, Richmond(from Sy and Campanella, 1992b)92B.C. PRESSURE—CORRECTED N ENERGY—CORRECTED Nb30EEC0ov —20—E0U,20 40BPT3—1 70mm60 0 208P13— 170mm605.7 SUMMARY AND RECOMMENDATIONS FOR ENERGY MEASUREMENTOF BPTTest data from the Richmond site confirm that the Harder and Seed (1986) bounce-chamber pressure correction procedure, although conceptually sound for correcting variablehammer combustion efficiencies, can not be consistently applied to different Becker rigs withdifferent hammer conditions. On the other hand, the results show that the proposed energy-correction method provides a simple and more fundamental approach for normalizing theBPT blow counts, regardless of combustion conditions or energy losses in the hammer andin the driving system.For BPT-SPT correlations, it is recommended that the transferred energies in the BPTbe measured with similar equipment currently used for dynamic monitoring of pile drivingin accordance with ASTM D4945-89. The instrumentation should consist of two sets offorce and acceleration transducers attached to a short (0.6 m) length of Becker pipe threadedto the top of the drill pipes during testing. The instrumented section should have the samediameter as the rest of the Becker pipes and is removed when the next length of pipe isadded. The measured transferred energies should then be used to correct the field blowcounts to a reference energy level of 30% as proposed here. The measured force andvelocity data will also allow quantification of the shaft resistances acting on the drill pipeduring the BPT, the effect of which must be considered in BPT-SPT correlations. This topicis discussed in the following chapter.93CHAPTER 6BPT-SPT CORRELATIONS WITH CONSIDERATION OF CASING FRICTION6.1 EXPERIMENTAL TEST SITESAt two test sites in the Fraser Delta, SPT, BPT and CPT were performed in acontrolled grid pattern, and dynamic measurements of the SPT and BPT were conducted.The test sites are the new Kwantlen College campus in Richmond (discussed in Chapter 5)and the Annacis north pier in Annacis Island. The SPT and BPT data from these two sitesare presented in this chapter to establish possible correlations between SPT and BPT.The SPTs were carried out in mud rotary drill holes. The dynamic measurements ofthe SPT were made with a piezoelectric load cell coupled with an accelerometer attachednear the top of the drill rods as described in Chapter 4. The transferred energies werecalculated using both the force integration and the force-velocity integration methods. Forthe SPT systems used in this study, the calculated energies by the two methods were close,generally within 10%. The measured SPT N-values were then corrected to N60 using Eq.[5.1].For the BPT, the Becker casing was instrumented with strain transducers andaccelerometers at 0.4 m below the top of the pipe and monitored using the Pile DrivingAnalyzer as described in Chapter 5. In addition, peak bounce-chamber pressure for everyblow during the BPT was automatically measured with a pressure transducer connected tothe end of a 15 m long hose and to a computer-based data acquisition system. The measuredBPT blow counts were then energy-corrected to Nb30 using Eq. [5.2]. For comparison, themeasured BPT blow counts obtained from AP1000-type Becker drill rigs were also corrected94to N, following the Harder and Seed (1986) bounce-chamber pressure correction proceduredescribed in Chapter 2. Only BPTs conducted with the 170 mm diameter casing areconsidered in the correlation study here. More details of the test measurements includingtest location plan and additional test data are given in Appendix A.6.2 SPT AND BPT RESULTSAs described in Chapter 5, the Richmond test site is underlain by 25 m of fine tomedium grained sands (see CPT data in Fig. 5.2). At this site, three CPTs, two drill holeswith SPTs, and five BPTs using different Becker drill rigs, variable combustion conditionsand different pipe sizes were conducted. However, only one BPT, i.e. BPT3, is used forcorrelation with SPT here.The two drill holes at the Richmond test site were carried out approximately 3 mapart using Foundex’s HT1000 truck-mounted drill rig. In both holes, the SPTs wereconducted at the same depths to a maximum depth of 24 m with an automatic trip hammerwhich gave average measured transferred energies of 55 to 60%. BPT3 was conducted alsoto 24 m depth, using an AP1000 drill rig (No. 107) with full throttle and 170 mm diametercasing. Figure 6.1 shows the energy-corrected SPT blow count (N60), bounce-chamberpressure-corrected (NbC) and energy-corrected (Nb30)BPT blow counts at the Richmond site.(The SPT energy data and other BPT measurements are enclosed in Appendix A.)The second research site is the Annacis test site. Here, one CPT, two drill holes withSPTs, and two BPTs were conducted. Figure 6.2 shows the CPT data at the Annacis site.The site is covered by about 3 m of sand fill over a 2 m thick natural silt stratum overlyingfine to medium grained, fairly clean sand to 37 m depth. A transition zone exists between95SPT N60 (blows/O.3m) BPT N (blows/O.3m) BPT Nb30 (blows/O.3m)o io 20 30 40 50 0 20 40 60 80 0 20 40 60 800_1111IHH11H1Ii111t1- iiIiiiIiiiIii —5—.- .10: 0- •oIDIC••0-20—- C.- ID25—RICHMOND SITE30— B.C. PRESSURE—CORRECTED ENERGY—CORRECTEDFig. 6.1 Corrected SPT (N60) and BPT (Nba and N0) blow counts vs depth,Richmond test site (from Sy and Campanella, 1993b)96ClD..=,U)mirnC1•<mT1Di_)c_i—-4—I11ri-4U)i—iii xJ—DEPTH(metres)C-)m rn—I:,-I-.4DiU)-.4rn U,U):C-)0)-ft)ci91—I——lCDr*CDcift)rn—oci_,‘-4EI—IaiJ‘-I-—CD0ci_,0ci—0-4,104rnrn-im ci37 m and 47 m, and comprises sand with interlayered silt. Below 47 m is a soft to firmclayey silt marine deposit which extends to about 90 m depth in this area.The two drill holes, approximately 4 m apart, were carried out using two differentdrill rigs and SPT hammer systems. In DH9O, two automatic trip hammers delivering 65to 85% of the theoretical free-fall SPT hammer energy were used, whereas in DH92, a donuthammer with an average transferred energy of only about 42% was used. Figure 6.3 showsthe energy-corrected SPT N60 values. The apparent “erratic” N60 values below 27 m reflectthe highly variable densities in the river sand deposits as confirmed by the CPT tip resistance(Q) profile shown in Fig. 6.2.The two BPTs, also 4 m apart, were conducted to investigate the effect of combustionconditions, similar to that conducted at the Richmond site as discussed in Chapter 5, but tomuch longer depth here. Both tests were performed with an AP1000-type drill (rig No. 102)and 170-mm diameter casing. BPT-B1 was conducted to 51.2 m depth with full throttle ormaximum fuel setting, while BPT-B2 was performed to 42.4 m with variable and reducedfuel throttle settings. The results of the dynamic measurements are presented in Fig. 6.4,which shows the measured blow count (Nb), peak bounce-chamber (BC) pressure, peak forceand maximum transferred energy (ENTHRU) plotted against depth. A total of 15,000 blowswas recorded for BPT-B1 and 15,500 blows for BPT-B2. As expected, the blow counts forreduced throttle or reduced fuel condition (BPT-B2) are higher than those for the full throttlecondition (BPT-B1), while the bounce-chamber pressures, peak forces and ENTHRU valuesare lower. During hard driving below 35 m, peak bounce-chamber pressures reached130 kPa, peak forces were up to 710 kN, while ENTHRU values remained generallyconstant at about 30%.98SPT N60 (blows/O.3m)o 25 50 750— I I I I I I I-I5-&10-ci15—20—- CCi— 30—uJ -C35— U- C40- C- CANNACIS SITE55 DDDCD DH9O••••U DH92Fig. 6.3 SPT N60 data, Annacis test site (from Sy and Campanella, 1993b)99(D - CID—,.— — Iz V 0 0, 0 3 C) -U ‘ii ci, Cl, C xl rn n -U 0 -o xl C) P1 n z P1 z -I xl CrioCMCM.C.C.13I3(710(710CM0(710DEPTH(m)C C11111111111IIIIliiiII1IIIIIIIIIItiiliiiliiiiliittIIIII(II,— -UI 0Figure 6.5 shows the measured BPT blow count (Nb), bounce-chamber pressure-corrected blow count (Nw), and energy-corrected blow count (Nb30) for BPT-B1 and BPT-B2.Note the large differences between the two measured blow count profiles, particularly above15 m and below 25 m, with some recorded blow counts as high as 600 blows per 0.3 m.However, when corrected to Nb or to Nb30, the two measured profiles again virtuallycollapse into one, as shown in Fig. 6.5.Figure 6.6 shows the bounce-chamber (BC) pressure and ENTHRU data plottedagainst the measured blow count (Nb). As expected, the reduced combustion (BPT-B2) datapoints lie above and to the left of the full combustion (BPT-B1) data points in both graphs,since blow count increases and bounce-chamber pressure decreases with decreasingcombustion efficiency or ENTHRU. For comparison, Harder and Seed’s calibration lineA-A is also shown on the bounce-chamber pressure versus Nb graph. It can be seen that allthe data points plot to the left of the A-A line, again confirming that Harder and Seed’s(1986) reference calibration line corresponds to energies higher than those measured at thissite.Another interesting observation is in the clayey silt below 47 m. Whereas the CPTQ and SPT N60 both show significant drop in values (see Figs. 6.2 and 6.3), the BPT blowcounts do not (Fig. 6.5). The measured BPT blow counts are more than 200 in this zonecompared to a SPT N of only 2 at 49 m depth, obviously a result of skin friction built-upon the Becker casing at large depth.The SPT and BPT blow counts from the Richmond and Annacis test sites are showntogether in Fig. 6.7, with SPT N60 plotted against both N1, and Nb30 values at thecorresponding SPT depth. Only SPTs in sands are presented in Fig. 6.7. For the Richmond101MEASUREDNb (blows/O.3m)0 125I I I I I LI_ I IB.C. PRESSURE—CORRECTEDN (blows/O.3m)125 250I I I I I I I I IENERGY—CORRECTEDN (blows/O.3m)125 250I I I I i i iFig. 6.5 Measured and corrected BPT blow counts vs depth, Annacis test site(from Sy and Campanella, 1993b)102250 0 05—10—15—20 —.—. 25:EI— 30—IJ -ID -35—40—45—50—55 —ANNACIS SITE— Bi: FULL THRO1TLE-- -- B2: REDUCED THROTTLE9kIIIc6__,-7-Ed0)0-D.0zFig. 6.6 Bounce-chamber pressure and ENTHRU vs blow count, Annacis test site(from Sy and Campanella, 1993b)1031000100 -10a4AA AA AAAA A‘Wa’A A. •‘•••A • ••a _..— •100 -10AAAA !4-.AjfA1I.AA••.A •A •I•• — I• I IANNACIS SITE‘a... 81: FULL THROTtLEAAAAA 82: RED. THROTtLE50I I I I I I I I I I I75 100 125B.C. PRESSURE (kPo)1:01111 11111111111 111111110 20 30 40 50ENTHRU (%)100nEr€)0_____ _____ _____ _____ _____ _____ _____ _____ _____0)000IDzI0(F)Fig. 6.7 SPT N60 vs BPT Nb and Nb30, Annaci.s and Richmond test sites(from Sy and Campanella, 1993b)104100—DDDDD RICHMOND80—:_____60—A 7 ‘Horder & Seed40--{20- - A- ci/r_80604020: OODDci RICHMONDA- A A. 0 A- A00 A 0 AAAr1lA AA—I I IIII III II I I I III — III III III II I0 20 40 60 50 100 0 20 40 60 80 100BPT N (blows/O.3m) BPT N0 (blows/O.3m)site, the average of two SPTs at the same depth is plotted. In the Nb30 versus N60 plot, twodata points with Nb30greater than 100 from the Annacis site are not shown, since these lieoutside the range of the plot. The data points in Fig. 6.7 cover BPT-SPT data in sands to43 m, BPT blow counts obtained on 170 mm diameter casing, and SPT N60 values up toabout 60. Both plots show similar vertical spread in the data but the Nb30 values are“stretched” in the X-axis relative to the NbC values. Also shown in the NbC versus N60 plotis Harder and Seed’s BPT-SPT correlation which appears to fit nicely through the middle ofthe data points, albeit with some large scatter.6.3 EFFECT OF CASING FRICTIONIn their study of the BPT, Harder and Seed (1986) indicated that casing friction hasa minimal effect on the Becker blow count and, hence, friction was not considered in theirBPT-SPT correlation. The Harder and Seed data base, although limited to 15 m depth, canbe replotted as shown in Fig. 6.8, with the blow count ratio, NbC/N60 against depth. Notethe increasing trend in the blow count ratio with depth, which would suggest increasingfriction on the Becker casing as the embedment increases. The effect of casing frictionwould also explain the bending down or concave shape of their proposed BPT-SPTcorrelation in Fig. 2.8.Stewart et al. (1990) found that casing friction can have a significant effect on theBPT blow count. At one test site, McDonald’s Farm, appreciable friction had built up tosuch an extent that a distinct stratigraphic unit change from dense sand to soft silt at 15 mcould not be detected by the BPT. This change was apparently marked by a sharp drop inboth CPT tip resistance and SPT N-values, similar to the observation noted above at the105NbC/N600.0 0.5 1.0 1.5 2.0— liii 111111111111112—4—6— i1:x 10—LU -0 12—.14—16—HARDER AND SEED DATA18— A SALINAS SITE-. THERMALITO SITE• SAN DIEGO SITE20 —_________________________Fig. 6.8 Harder and Seed’s blow count ratio, Nb/N, vs depth(from Sy and Campanella, 1993b)106Annacis test site below 47 m. At another reported test site, Duncan Dam, large diametercasings were installed in three holes to 5, 40 and 55 m depths and BPTs were conductedthrough the pre-cased holes. Not surprisingly, the blow counts at the same depth reducedwith increased cased length, again, due to the effect of friction on the uncased or embeddedportion of the Becker pipe.Clearly, casing friction in the BPT can not be ignored if reliable and useful BPT-SPTcorrelations are to be established, particularly for use at large depth. Also, the frictionaleffects must be quantified if the correlations developed on sand sites (in order to minimizethe effect of particle size on SPT N-value) are to be applicable to gravelly sites.Another way of looking at friction on the Becker pipe, and, in fact, a more directway, is through stress wave measurements and application of wave mechanics principles.As discussed earlier, for impact wave propagation in one direction in a uniform unsupportedelastic rod, the force at a point in the rod is equal to the particle velocity at that point timesthe impedance. Therefore, when the force and the velocity times impedance are plotted tothe same scale, the two traces will plot on top of each other until upward travellingreflections reach the measurement location. For a rod of uniform cross section having nosoil resistance, the first upward travelling wave will be from the toe and will arrive at time2L’/c after impact, where L’ = length of pipe below transducer location and c = wavespeed in steel. External soil resistance will also cause upward travelling reflection that willarrive at time 2X/c, where X is the distance from the measurement point to the location ofthe soil resistance. The upward travelling wave due to soil resistance will be compressive,with an amplitude proportional to the magnitude of the soil resistance. These upwardtravelling compressive waves will cause an increase in force and a decrease in velocity107recorded near the top of the pipe, i.e. a separation of force and velocity. The greater theseparation, the greater is the shaft resistance. This principle is illustrated schematically inFig. 6.9 showing the effect of soil resistance on a friction pile.Figure 6.10 shows measured wave traces of representative hammer blows at 15, 30,43 and 49 m depths from BPT-B1 at the Annacis test site. The wave traces shown are theforce and the velocity normalized by the pipe impedance, EA/c. For the 170 mm diametercasing used in this test, EA/c = 322 kN/mls. The wave return period after impact, 2L’Ic,is indicated by the horizontal bar, the far end of which marks the wave reflection from thepipe toe. The wave traces clearly show increasing force-velocity separation, i.e. pipefriction, with increasing pipe penetration or embedment.The soil friction and its distribution along the Becker pipe can also be quantified byCAPWAP analysis (Rausche et al., 1985b), another recognized technique used in piledynamics. CAPWAP is a proprietary computer program developed by Goble Rausche Likinsand Associates, Inc. (GRL) and which uses the force and velocity traces obtained with thePile Driving Analyzer to evaluate the pile and soil boundary conditions through a trial anderror process of signal matching in a wave equation analysis. The boundary conditions arethe pile impedances, soil resistance distribution, soil quake and damping characteristics. Theresults of CAPWAP analyses of five selected blows from different depths in BPT-B1 at theAnnacis test site are summarized in Table 6.1. Also shown in Table 6.1 are the measuredBPT Nb30 and SPT N60 values at the five depths analyzed. (The CAPWAP analyses wereperformed by GRL of Seattle, Washington, and the detailed outputs are enclosed inAppendix B.)108Fig. 6.9 Effect of soil resistance on stress waves in pile109IC-)LU>zLUC-)FORCEVELOCITYTIMEUFRICTION PILE750-:_____- Force ANNACIS — 15.2 mz - ----V*EA/c- 500—o250-*>I I2L/c I—250— I I I750 —z -- 500—0a’3o.5m250-*>—250— I I750 —42.7 mz -- 500—0250—*> 0-__________________________________________Li : I __---__I—250— I I I I750 —z -- 500—0 - jl% 48.5rn250-*> 0——250— IIIIIIIIIIIIIIIIIIIIIIIIIIIIIr+1I0 5 10 15 20 25 30 35 40 45 50TIME (ms)Fig. 6.10 Measured BPT wave traces, Annacis test site(from Sy and Campanella, 1993b)110Table 61 Summary of CAPWAP resistances and measured BPT-SPT blow counts,Annacis test sitePipe Shaft Toe Total Measured MeasuredEmbedment Resistance Resistance Resistance BPT Nb30 SPT N(m) (kN) (kN) (kN)9.1 120 31 151 19 1012.2 147 53 200 26 1415.2 156 44 200 28 2321.3 188 66 254 46 3342.7 356 111 467 181 56As shown in Table 6.1, the computed total shaft resistance increases with increasingembedment or pipe penetration. The shaft resistances, even at shallow depths, are 3 to 4times the corresponding toe resistances, indicating the significant effect of pipe friction inthe BPT. The relative differences between the Nb30 and corresponding N values alsoprovide another indication of the effect of friction, particularly at large depth. One couldpostulate, then, that if shaft resistances were somehow absent, the Becker blow counts wouldreduce significantly. The SPT blow counts would, of course, remain unchanged.Fortunately, the effect of friction on the BPT blow count can be evaluated theoretically bywave equation analysis as described below. The wave equation analysis also provides ameans of incorporating casing friction in BPT-SPT correlations.6.4 PROPOSED BPT-SPT CORRELATIONSWave equation analyses of the BPT were conducted, using the GRLWEAP program,at the five selected depths for which CAPWAP analyses were performed. As a first step,111each wave equation model was calibrated as follows. The results of the CAPWAP analyses(see Appendix B) were used to provide the pipe and soil input parameters in the waveequation analysis. It should be noted that the CAPWAP analytical model is similar to thewave equation model except that the former does not include the driving system. Anotherinput parameter in the wave equation program is the hammer efficiency which accounts forenergy losses in the hammer and which is used to calculate the hammer impact velocity tostart the dynamic analysis. The hammer efficiency was varied in the wave equation analysisuntil the computed ENTHRU matched the field measured ENTHRU. In all cases, thecomputed blow counts were found to be close to the field recorded blow counts.After the wave equation model was calibrated, the shaft or side resistance componentwas removed in the subsequent analysis and a “frictionless” BPT blow count predicted. Thecomputed blow count was normalized to ENTHRU of 30% using Eq. [5.2]. For the fivedepths analyzed, the measured Nb30 and corresponding computed “frictionless” Nb30 areplotted against SPT N60 in Fig. 6.11. The CAPWAP-computed total shaft resistances (Rs)are also shown for the five measured data points. Note the significant drop in BPT blowcounts when the shaft resistances are removed in the wave equation analysis. Also, thecomputed zero shaft resistance (Rs=0) blow counts fall almost in a straight line, with a slopeof approximately 2.5 to 1. These results have important implications, and illustrate that fora given SPT N60, there is a wide range of possible BPT Nb30 values depending on the amountof shaft friction acting on the Becker pipe.The wave equation analyses were carried one step further by assigning a series oftotal shaft resistances, i.e. Rs = 45, 90, 135, ... 360 kN, to each BPT model and computingthe blow count corresponding to each given Rs. From these analyses, contours of equal Rs112Fig. 6.11 Effect of casing friction on BPT blow count Annacis test site(from Sy and Campanella, 1993b)113‘-S2Ii0Cl)0-o0zI—0Cl)100806040200-ANNACIS TEST SITEA CAPWAP Rs (kN)- Rs=0 * Calculated Rs=0-—---—----355 kN: Ai N: /-----<---A156kN,4---.<-- --A147 N120 kNII I I II III0 20 40 60I I I I I I I I I I I I80 100 120BPT Nb30 (blows/O.3m)1 ‘f0I I I I I I160I I IitsO 200can be drawn as shown in Fig. 6.12. It is interesting to note that the shape of the Rs contouris bending upward or convex, as opposed to Harder and Seed’s correlation curve which isbending downward or concave. Although the Harder and Seed’s correlation curve is basedon Nk, it is not hard to imagine that it would “pass” or “cut” through increasing Rs contoursas the blow count increases, suggesting that their correlation has embedded site-specificfriction effects, the magnitude of which appears to increase with increasing blow count.Because their correlation was developed on sites having sand and silt subsoils, its applicationto other sites with different frictional characteristics, e.g. in gravelly soils, may not beappropriate.Sensitivity analyses were also performed by varying the key input parameters in thewave equation models, including hammer efficiency, pipe length, shaft resistancedistribution, and soil damping. It was found that the theoretical curves in Fig. 6.12 werereasonably robust for the average expected conditions on granular soil sites, and as such,could provide a rational basis for BPT-SPT correlations with consideration of casing friction.It should be noted that Rs refers to the total static shaft resistance mobilized on a 170 mmO.D. Becker pipe during the BPT.114100:80Rs=0 kN 45 90 135 180 225//,///,/315OZ 111111111 111111111 111111111 111111111 1111111110 20 40 60 80 100BPT Nb30 (blows/O.3m)Fig. 6.12 Computed BPT-SPT correlations for different BPT shaft resistances (Rs)(from Sy and Campanella, 1993b)115I060(I) -0 -_o -aCDzI—0(I)20CHAPTER 7VERIFICATION OF BPT-SPT CORRELATIONSAn opportunity arose for independent verification of the proposed BPT-SPTcorrelations in a research project conducted by Foundex Explorations Ltd. at the Tower 5/4test site in Delta to investigate a new BPT technique (Li and Wightman, 1992). In the newlydeveloped technique, called the Foundex Becker penetration test (FBPT), bentonite drillingmud is pumped down the Becker pipe and comes out through a series of holes just behindan oversized sleeved close-ended pipe section. In this manner, the shaft friction issubstantially reduced compared to a conventional BPT.Figure 7.1 shows data from a CPT at the Delta test site. The site is underlain by a1.5 m thick surficial silt layer overlying a fine, fairly clean sand deposit to 41 m depth.Below 41 m is sand with stratified silt layers.As part of the testing program at the Delta site, dynamic measurements of SPTs intwo drill holes and of two types of BPTs were conducted. The SPTs were carried out withan automatic trip hammer which delivered energies of 60 to 70% to the drill rods. AHAV 180 type Becker drill rig was used for the BPTs. FBPT5 was performed with the newmud-injection technique and with a 170 mm diameter by 300 mm long shoe at the end of a140 mm diameter pipe, while BPT1O was a “regular” or conventional BPT conducted witha constant 170 mm diameter pipe. Both tests, therefore, have the same toe diameter or endarea.The measured and energy-corrected BPT and SPT data at the Delta test site arepresented in Fig. 7.2. The left plot shows the Nb30 profiles for FBPT5 and BPT1O, as well116C6’)0-1xim-1,-arnm-im ciDEPTH(metres)C Cr) 3cirnci‘-‘-cirn 3,-xlcl-Di-3ci, U)-1 :1,I,,U)U)U)F— mU)mci-xlDi -,F-i---1 I-’cici-n U) :ixiF-)-4I—’ID -II.-’ci0-ii-i)CDCDCDci_JciC Cr3m = ‘-Iaci-t-1Di0‘-I‘—CD•TD—-3CD0ICu)QU)ILI)-,.ri-D3>.-,-I—=I—IID—iIDCDNb30 & N60 (blows/O.3m) Nb30/Nsoo 50 100 150 200 0.0 1.0 2.0 3.00— liii tIll 1111111111111 11111 iii iii in ii — ii I Iii I I II IIDELTA SITE ..... FBPT5/SPT-oooo-e BPT1O/SPT5 FBPT5 N0---- BPT1O Nb5,Fig. 7.2 Corrected SPT (N60) and BPT (N) blow counts vs depth, Delta test site(from Sy and Campanella, 1993b)118as the SPT N60 values in sand. The horizontal separation between BPT1O and FBPT5profiles is a measure of the effect of friction. Note how the separation increases withincreasing depth, suggesting pipe friction “growing” with embedment. In fact, several siltlayers below 40 m depth as identified by FBPT5, and confirmed by adjacent CPT’s, werecompletely “missed” by BPT1O. The right plot in Fig. 7.2 shows the BPT-SPT blow countratios, Nb3O/N, versus depth for FBPT5 and BPT1O. These blow count ratios againillustrate the dramatic effect of pipe friction on the BPT blow count.The BPT Nb30 values are plotted against the SPT N values in Fig. 7.3. For eachSPT N, there are two corresponding Nb30 values, i.e. one for FBPT5 (filled circle) and onefor BPT1O (empty circle). It can be seen that the effect of removing pipe friction is to shiftthe BPT blow counts to the left, an observed trend in agreement with the computed waveequation results in Fig. 6.12.The energy-corrected BPT-SPT data in sand from the Delta, Annacis and Richmondtest sites are all plotted in Fig. 7.4, together with the computed correlations from Fig. 6.12.As shown, the Delta mud-injection (FBPT5) data points lie in a reasonably narrow bandbetween Rs curves of 0 and 45 kN. On the other hand, the data points for the regular orconventional BPTs lie to the right of the FBPT data and cover a wide range of Rs values.A closer examination of these BPT data points indicates that most of the shallow data, upto 10 m depth, lie between Rs curves of 45 kN and 135 kN, whereas below 20 m depth,most of the data lie beyond Rs of 180 kN. This is not surprising, since total shaft resistancein sands invariably increases with depth or pipe embedment.The results shown in Fig. 7.4 are encouraging and suggest that the BPT-SPTcorrelations derived from wave equation analyses can provide a useful framework for119Fig. 7.3BPT Nb30 (blows/0.3m)SPT N vs BPT N0, Delta test site (from Sy and Campanella, 1993b)120Cl)00(00C,)100806040200: DELTA TEST SITE• FBPT5 vlud—lnjection: 0 BPT1O Regular• • o0 cP°- I 0: • I 0 0- II 0 0: •• ) 0.‘0 0- p: •• 00- •o0111111 I 1111111 111111111 111111111 11111111120 40 60 80 100BPT Nb30 (blows/O.3m)Fig. 7.4 Computed BPT-SPT correlations with measured data from Delta, Annacisand Richmond test sites (from Sy and Campanella, 1993b)ICl)00CozF—0(I)100806040200: • DELTA Mud—InjecUon: 0 DELTA Regular- ANNACIS Regular: D RICHMOND Regular-Rs=0 45 90 135 180 225 kNi_ ///// /I_____z/ 360liii; liii 111111111 11111 I II0 20 40 60 80 100II I liii121determining equivalent energy-corrected SPT blow count (N60) from energy-corrected BPTblow count (Nb30). Since Becker casing friction or shaft resistance is accounted for, theproposed correlations should also be applicable to gravel sites for which the BPT has provento be a most practical and economical testing technique. So given a BPT Nb30 and Rs valueat a depth, the equivalent SPT N60 can be determined from the appropriate Rs curve in Fig.6.12.122CHAPTER 8RECOMMENDED PROCEDURE FOR ESTIMATING EQUIVALENT SPT NThe recommended procedure for estimating equivalent SPT N60 values given BPTblow counts from a 170 mm O.D. Becker pipe are:1. Monitor BPT with the Pile Driving Analyzer in accordance withASTM Standard D4945-89 to determine the maximum transferredenergies (ENTHRU).2. Correct the recorded blow counts to Nb30 using Eq. [5.2] and theaverage ENTHRU value per 0.3 m.3. Select representative blows for CAPWAP analysis to determine thetotal shaft resistances (Rs) at critical depths, and estimate orinterpolate between computed Rs values for other depths.4. With the energy-corrected BPT Nb30 and Rs values, estimate equivalentSPT N60 from Fig. 6.12.The above procedure is applied to BPT-B1 and BPT-B2 at the Annacis site (see themeasured blow count profiles in Fig. 6.5) and the results are presented in Fig. 8.1, whichshows the Nb30, Rs and equivalent N60 values plotted against depth. For comparison, themeasured SPT N60 values from the two adjacent drill holes are also plotted in Fig. 8.1. Asshown, the measured SPT blow counts are in good agreement with the estimated N60 values.Although the horizontal scales for the BPT Nb30 and equivalent SPT N60 plots aredifferent in Fig. 8.1, the results clearly indicate that at the same depth or for the same Rs,the estimated equivalent N60 value is sensitive to the measured Nb30. In other words, a smalldifference in Nb30 values (between BPT-B1 and BPT-B2) results in a larger difference inequivalent N60 values. This feature is because of the bending upward or convex shape of the123BPT N0 (blows/O.3m) Rs (kN) SPT N (blows/O.3m)o 125 250 0 200 400 0 50 1000.._hhhhhhhhhhhIhhhhhI _,iiiiiiiItiiiiiiii_(5—’-.--15—-20= ç---I— - -- .- -LiJ -030—---40=45 —ANNACIS SITEd — Equivalent (BPT 81— BPT Bi sume Equivalent (BPT 8250= BPT 82* CAPWAP • Measured (DH9O/92)Fig. 8.1 Corrected BPT blow count (Nb30), shaft resistance (Rs), and equivalentand measured SPT blow counts (N6) vs depth, Annacis test site(from Sy and Campanella, 1993b)124computed Rs contours in Fig. 6.12. This characteristic behaviour is not surprising when oneconsiders that the typical transferred energy in the BPT (3.3 kJ) is about ten times that in theSPT (0.3 U), whereas the soil-probe contact area in the BPT over the bottom 0.3 m interval(and neglecting shaft friction) is only about 2 to 3 times that of the SPT soil-sampler contactarea.The proposed BPT-SPT correlations in Fig. 6.12 apply to BPT conducted with the170 mm size casing or pipe. If the 140 mm pipe is used, the pipe size correction factor inEq. [5.4] can be used to convert the measured blow counts to equivalent 170 mm-pipe blowcounts. The calculated Rs values for the 140 mm pipe should also be increased by a factorof 1.2 (i.e. ratio of the pipe diameters, 170/140) before entering into Fig. 6.12.125CHAPTER 9SUMMARY AND CONCLUSIONS9.1 SUMMARY OF RESEARCH STUDYExperimental and numerical studies of the SPT and BPT have been conducted withthe ultimate objective of obtaining reliable BPT-SPT correlations. The research involvesperforming SPT, BPT and CPT at four research sites in the Fraser delta south of Vancouver.The field experiment includes dynamic measurements of energy transfer in both the SPT andBPT.The current methods of energy calibration of the SPT and BPT are investigated. Analternative and more rational approach of energy measurement, based on force andacceleration measurements near the top of the drill pipes, is proposed for both the SPT andBPT. The proposed approach provides a unified method of measuring transferred energiesin the SPT and BPT, similar in principle to that used in pile driving. The measuredtransferred energies are used to correct the measured blow counts for the variable hammerenergies in each test.Stress wave measurements and wave equation analyses are used to evaluate the effectof casing friction on the BPT blow count. Finally, new BPT-SPT correlations, withconsideration of casing friction, are proposed. The correlations are subsequently verified byindependent data at another research site.The major findings and conclusions of this research study are presented below.1269.2 DYNAMIC MEASUREMENTS OF SPTThe current force integration method of SPT energy determination as specified inASTM D4633-86 and ISSMFE (1988) has several inherent assumptions and limitations,including the use of three controversial K-correction factors.An alternative and more fundamental approach of determining the SPT energy,similar in concept to that currently used in dynamic testing of piles, is proposed. Thismethod requires an additional measurement of motion (usually acceleration), but avoids theshortcomings in the existing force integration method. Furthermore, the quality of themeasured data can be checked in the field by inspection of the force/velocity proportionality.It is shown that the force integration method gives approximate energy values that aresufficiently useful for many SPT systems, provided the drill rods are not very short and donot contain significant cross-sectional area changes. It is also shown that the three K-correction factors have weak theoretical justification and should not be applied in the forceintegration method to determine the transferred energy.Both theory and data show that for a given SPT system with a constant energy lossfactor, the peak force near the top of the rods is a function only of the hammer drop height,regardless of the length of the rods or soil conditions. Thus the consistency of measuredpeak forces can provide another check on the quality of the force measurement.9.3 DYNAMIC MEASUREMENTS OF BPTThe Harder and Seed (1986) method of correcting the BPT blow count to a constantcombustion condition by measuring peak pressures in the bounce chamber of the dieselhammer can not capture all the important variables affecting the penetration resistance or127blow count of the Becker casing. Their bounce-chamber pressure correction method,therefore, can not be generally applied to different Becker rigs with different hammerconditions.This study shows that the current approach for dynamic testing of piles as specifiedin ASTM D4945-89 can equally be applied to the BPT. The measured transferred energyprovides a useful and fundamental parameter to characterize the variable energy output fromthe diesel hammer. Accordingly, a simple procedure for correcting the BPT blow count toa reference energy level of 30% of the hammer rated energy, similar in concept to that usedfor the SPT, is proposed for the BPT.9.4 BPT-SPT CORRELATIONSData show that casing friction has a significant effect on the BPT blow count,particularly at large depth. Stress wave measurements and CAPWAP analysis can be usedto quantify the casing friction in the BPT. New BPT-SPT correlations are proposed whichconsider the energy transfer in both tests and which, for the first time, explicitly considercasing friction in the BPT.It is shown that the proposed BPT-SPT correlations provide a rational and practicalframework for determining equivalent SPT N60 values from measured BPT blow counts.Since casing friction is accounted for, the proposed correlations should also be applicable togravel sites for which the BPT is most useful and economical.1289.5 RECOMMENDATIONS FOR FUTURE RESEARCHThe SPT will continue to be the most widely used in-situ test in North America formany years to come. To use this tool more effectively and reliably, the transferred energyshould ideally be measured for every test. There is, therefore, a need for a simple, reliableand economical commercial system for SPT energy measurement. Although themeasurement of force and acceleration in the SPT provides a more fundamental approach totransferred energy determination, more research is needed on the instrumentation aspects ofthe measurement. The steel-to-steel impact in the SPT, with its inherently high accelerationsand frequencies, causes havoc for most instruments. At present, there is no generalconsensus on the best types of transducers to use.The BPT, or some other type of large-scale dynamic penetration test, will continueto find a useful role in gravelly soils. The effect of casing friction in the BPT is one of themost important factors affecting its usefulness. This research has demonstrated that stresswave measurements and CAPWAP analysis can be used to quantify the casing friction in theBPT, leading to rational BPT-SPT correlations. A more direct and simple determination ofthe dynamic friction from stress wave measurements, however, will make the approach evenmore practical.The proposed BPT-SPT correlations were developed and verified at research sites inthe Fraser delta in mostly fine to medium grained sands. More verifications at other sitesin different geologic environments will provide further cheek on the general applicability ofthe proposed correlations.The dynamic cone penetration test, also widely used in practice for estimatingequivalent SPT N-values, has much the same problems as the BPT, i.e. variable hammer129energy transfer and rod friction. A similar approach to the BPT-SPT correlations presentedin this thesis could also be considered for the dynamic cone penetration test.130BIBLIOGRAPHYAdam, 3. 1971. Discussion of “The standard penetration test” by V.F.B. de Mello. Proc.4th Panamerican Conf. on Soil Mech. and Found. Eng., Vol.3, 82-84.Anderson, L.G. 1968. A modern approach to overburden drilling. 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Balkema Publishers, 99-103.Goble, G.G., Rausche, F. and Likins, G.E., 1980. The analysis of pile driving - a state-of-the-art. Proceedings of the 1st Tnt. Conf. on the Application of Stress-Wave Theory onPiles, Stockholm, Sweden, A.A. Balkema Publishers, 131-161.Hall J.R. 1982. Drill rod energy as a basis for correlation of SPT data. Proc. ESOPT-2,Amsterdam, 57-60.Hanskat, C.S. 1978. Wave Equation Simulation of the Standard Penetration Test, MEngThesis, University of Florida, Gainesville.Harder, L.F. Jr. 1992. Investigation of Mackay Dam following the 1983 Borah Peakearthquake. Stability and Performance of Slopes and Embankments II, ASCE GeotechnicalSpecial Publication No. 31, 2: 956-972.Harder, L.F. Jr. and Seed, H.B. 1986. Determination of penetration resistance for coarsegrained soils using the Becker hammer drill. Report No. UCB/EERC-86/06, EarthquakeEngineering Research Center, University of California, Berkeley.Ireland, H.O., Moretto, 0. and Vargas, M. 1970. The dynamic penetration test: a standardthat is not standardized. Geotechnique, 20(2): 185-192.ISSMFE 1988. Standard penetration test (SPT): International reference test procedure.ISSMFE Tech. Committee on Penet. Testing, ISOPT 1, Orlando, Florida, USA, Vol.1, 3-26.Kovacs, W.D. 1979. Velocity measurement of free-fall SPT hammer. ASCE Journal ofGeot. Eng., 105(GT1): 1-10.Kovacs, W.D. 1984. Discussion of “Reproducible SPT hammer impact force with anautomatic free fall SPT hammer system” by C.O. Riggs, N.O. Schmidt and C.L. Rassieur.ASTM Geot. Test. Journal, 7(4): 223-224.Kovacs, W.D., Evans, J.C. and Griffith, A.H. 1977. Towards a more standardized SPT.Proc. 9th ICSMFE, Tokyo, Vol.2, 269-276.Kovacs, W.D., Griffith, A.H. and Evans, J.C. 1978. An alternative to the cathead and ropefor the standard penetration test. ASTM Geot. Testing Journal, 1(2): 72-81.Kovacs, W.D. and Salomone, L.A. 1982. SPT hammer energy measurement. ASCEJournal of Geot. Eng., 108(GT4): 599-620.132McLean, F.G., Franklin, A.G. and Dahistrand, T.K. 1975. Influence of mechanicalvariables on the SPT. Proc. of the Conf. on In Situ Meas. of Soil Properties, ASCE, Vol.1,287-3 18.Mohr, H.A. 1966. Discussion of “Standard penetration test: its uses and abuses” by G.F.A.Fletcher. ASCE Journal of the Soil Mech. and Found. Div., 92(SM1): 196-199.Morgano, C.M. and Liang, R. 1992. Energy transfer in SPT - Rod length effect. Proc. 4thmt. Conf. on the Application of Stress-Wave Theory to Piles, The Hague, The Netherlands,A.A. Balkema Publishers, 121-127.Morrison, K.I. and Watts, B.D. 1985. Soil modulus, friction and base resistance fromsimple pile load tests on end-bearing piles. 38th Canadian Geotechnical Conference,Edmonton, Alberta, 273-281.Naesgaard, E., Sy, A. and Clague, J.J. 1992. Liquefaction sand dykes at Kwantlen College,Richmond, B.C. Geotechnical and Natural Hazards, Symposium of the VancouverGeotechnical Society and the Canadian Geotechnical Society, Vancouver, B.C., 159-166.Palacios, A. 1977. The theory and measurement of energy transfer during standardpenetration test sampling. Ph.D. thesis, Department of Civil Engineering, University ofFlorida, Gainesville, Florida, 391 pages.Rausche, F., Likins, G.E.,Jr., Goble, G.G. and Miner, R. 1985a. The performance of piledriving systems. Main report, Vol. 1 to 4, Federal Highway Administration contract#DTFH 6 1-82-C-00059, Washington, D.C., USA.Rausche, F., Goble, G.G. and Likins, G.E. Jr. 1985b. Dynamic determination of pilecapacity. ASCE Journal of Geot. Eng., 111(3): 367-383.Riggs, C.O., Mathes, G.M. and Rassieur, C.L. 1984. A field study of an automatic SPThammer system. ASTM Geot. Testing Journal, 7(3): 158-163.Riggs, C.O., Schmidt, N.O. and Rassieur, C.L. 1983. Reproducible SPT hammer impactforce with an automatic free fail SPT hammer system. ASTM Geot. Testing Journal, 6(3):201-209.Robertson, P.K., Campanella, R.G. and Wightman, A. 1983. SPT-CPT correlations.ASCE Journal of Geot. Eng., 109(11): 1449-1459.Robertson, P.K., Woeller, D.J. and Addo, K.O. 1992. Standard penetration test energymeasurements using a system based on the personal computer. Canadian GeotechnicalJournal, 29:551-557.Sanglerat, G. 1972. The penetrometer and soil exploration. Developments in Geot. Eng.1, Elsevier Pubi. Co.133Schmertmann, J.H. 1978. Use the SPT to measure dynamic soil properties?-yes, but..!Dynamic Geotechnical Testing, ASTM STP 654, 34 1-355.Schmertmann, J.H. 1979. Statics of SPT. ASCE Journal of Geot. Eng., 105(GT5): 655-670.Schmertmann, J.H. and Palacios, A. 1979. Energy dynamics of SPT. ASCE Journal ofGeot. Eng., 105(GT8): 909-926.Schmertmann, J.H., Smith, T.V. and Ho, R. 1978. Example of an energy calibration reporton a standard penetration test (ASTM standard D1586-67) drill rig. ASTM Geot. TestingJournal, 1(1): 57-61.Seed, H.B., Tokimatsu, K., Harder, L.F., and Chung, R. 1985. Influence of SPTprocedures in soil liquefaction resistance evaluations. ASCE Journal of the GeotechnicalEngineering Division, 111(12): 1425-1445.Skempton, A.W. 1986. Standard penetration test procedures and the effects in sands ofoverburden pressure, relative density, particle size, ageing and overconsolidation.Geotechnique, 36(3): 425-447.Smith, E.A.L. 1960. Pile driving analysis by the wave equation. ASCE Journal of SoilMechanics and Foundations Division, 86(SM4): 35-61.Smith, T.V. 1977. A summary of energy calibration tests on SPT equipment. MEngThesis, University of Florida, Gainesville.Stewart, R.A., Kilpatrick, B.L. and Cattanach, J.D. 1990. The use of Becker penetrationtesting for liquefaction assessment of coarse granular overburden. 43rd CanadianGeotechnical Conference, Quebec, 1: 275-283.Stokoe, K.H., Andrus, R.D., Rix, G.J., Sanchez-Salinero, I., Sheu, J.C. and Mok, Y.J.1988. Field investigation of gravelly soils which did and did not liquefy during the 1983Borah Peak, Idaho, earthquake. Geot. Eng. Report GR87-1, Civil Eng. Department,University of Texas at Austin.Sy, A. and Campanella, R.G. 1991a. An alternative method of measuring SPT energy.Proceedings of the 2nd International Conference on Recent Advances in GeotechnicalEarthquake Engineering and Soil Dynamics, St. Louis, Missouri, 1: 499-505.Sy, A. and Campanella, R.G. 199 lb. Wave equation modelling of the SPT. GeotechnicalEngineering Congress, ASCE Geotechnical Special Publication No. 27, 1: 225-240.134Sy, A. and Campanella, R.G. 1992a. Dynamic measurements of the Becker penetration testwith implications for pile driving analysis. Proceedings of the 4th International Conferenceon the Application of Stress-Wave Theory to Piles, The Hague, The Netherlands, A.A.Balkema Publishers, Rotterdam, pp. 471-478.Sy, A. and Campanella, R.G. 1992b. Dynamic performance of the Becker hammer drill andpenetration test. 45th Canadian Geotechnical Conference, Toronto, Ontario, Paper 24: 1-10.(Also approved for publication in the August 1993 issue of the Canadian GeotechnicalJournal.)Sy A. and Campanella, R.G. 1993a. Discussion of “Standard penetration test energymeasurements using a system based on the personal computer” by P.K. Robertson, D.J.Woeller and K.O. Addo. Approved for publication in the October 1993issue of theCanadian Geotechnical Journal.Sy, A. and Campanella, R.G. 1993b. BPT-SPT correlations with consideration of casingfriction. 46th Canadian Geotechnical Conference, Saskatoon, Saskatchewan, Sept. 27-29.(Also submitted for publication in the Canadian Geotechnical Journal.)Sykora, D.W., Loester, J.P., Wahi, R.E. and Hynes, M.E. 1992. Post-earthquake slopestability of two dams with liquefied gravel foundations. Stability and Performance of Slopesand Embankments II, ASCE Geotechnical Special Publication No. 31, 2: 990-1005.Terzaghi, K. and Peck, R.B. 1948. Soil mechanics in engineering practice. John Wiley &Sons Inc.Timoshenko, S.P. and Goodier, J.N. (1970), Theory of Elasticity, McGraw-Hill Inc.Valera, J.E. and Kaneshiro, J.Y. 1991. Liquefaction analysis for rubberdam and reviewof case histories of liquefaction of gravels. Proc. of the 2nd mt. Conf. on Recent Advancesin Geot. Earthquake Eng. and Soil Dynamics, St. Louis, Missouri, 1: 347-356.Yan, L. and Wightman, A. 1992. A testing technique for earthquake liquefaction predictionin gravelly soils. Report by Foundex Explorations Ltd. and Klohn Leonoff Ltd. to NationalResearch Council of Canada, Contract No. IRAP-M 40401W.Yokel, F.Y. 1982. Energy transfer in standard penetration test. ASCE Journal of theGeotechnical Engineering Division, 108(GT9): 1197-1202.135APPENDIX AADDITIONAL SOiL INFORMATION AND TEST DATAThis appendix presents additional background soil information and details of testmeasurements (CPT, SPT and BPT) at the research test sites investigated in this study. Thetest thta presented here (some were partially discussed in the main body of this thesis) areincluded for completeness. Fig. A. 1 shows the locations of the four research test sites whichare all located in the Fraser River delta region south of Vancouver, British Columbia.The Fraser delta is underlain by deep deposits of Holocene (postglacial) sediments up toabout 200 m thick. The deposits generally consist of fine silty overbank deposits typically2 to 3 m thick (Unit 1) overlying sand-sized marine and tidal flat deposits usually 15 to 50 mthick (Unit 2), which in turn overlie unconsolidated fine-grained marine sediments (Unit 3 -silts and clays). The investigations reported in this study were conducted mainly in theUnit 2 materials which consist predominantly of fine to medium grained, fairly clean sandswith some coarser sand and silty interbeds or lenses.Details of the CPT, SPT and BPT, and the measured test data are presented below for thefollowing three sites: Kwantlen College, Richmond; Annacis north pier, Annacis Island, andTower 5/4, Delta.136KWANTLEN COLLEGE, RICHMONDFigure A.2 shows the test hole location plan at the Richmond test site. As shown, threeCPTs, two drill holes with SPTs, and five BPTs were performed. The CPTs were conductedby Foundex Explorations Ltd. using a Geotech 10 cm2 3-channel (tip, sleeve and porepressure measurements) cone. The CPT data (CPT91-01, CPT91-02 and CPT91-03) arepresented in Figs. A.3 to A.5. The SPTs were performed in mud rotary boreholes drilledusing Foundex’s HT1000 drill rig (No. 11). An automatic trip hammer and AW rods wereused for the SPTs. Figure A.6 shows dimensions of the automatic trip hammer. The SPTenergy measurement data are summarized in Figs. A.7 and A.8 for DH91-01 and DH91-02,respectively.Table A. 1 summarizes characteristics of the five BPTs conducted at the Richmond test site.The first two BPTs were carried out with the Foundex’s HAV 180 Becker drill rig, while thelast three were done with Beck’s AP1000 Becker rig (No. 107). Note that although data forall five BPTs are presented here, there were some doubts on the reliability of the measuredblow counts for BPT1. Figs. A.9 to A. 11 show plots of the measured blow counts (Nb),bounce-chamber pressures (BP), and transferred energies (ENTHRU), respectively, versusdepth for all five BPTs at the Richmond test site.TABLE A.1Characteristics of BPTs conducted at Richmond test siteBPT Max. Fuel Casing Inner Becker DrillNo. Depth Setting O.D. Pipe Type - Rig No.(m) (mm) Type1 24.1 Full 140 Fixed HAV18O - Fl2 24.1 Full 140 Fixed HAV18O - Fl3 24.1 Full 170 Floating AP1000 - 1074 8.8 Reduced 170 Floating AP1000 - 1075 28.0 Full 140 Floating AP1000 - 107137ANNACIS NORTH PIER, ANNACIS ISLANDFigure A. 12 shows the test hole location plan at the Annacis test site. As shown, one CPT,two drill holes with SPTs, and two BPTs were carried out here. The CPT was conductedwith the UBC’s 10 cm2 Hogentogler cone (No. 3) on September 13, 1990 to a depth of51 m. Figure A. 13 shows the CPT data.The first drill hole, DH9O, was carried out on October 25 to 26, 1990 using the Foundex’sHT1000 drill rig. The SPTs in DH9O were performed to 49 m with two automatic triphammers using AW rods for tests to 9.3 m depth and BQ rods thereafter. Figure A. 14shows the measured N-value and energy ratio versus depth, and Fig. A. 15 shows the energy-corrected blow count (N60), mean grain size (D50), and fines content (% minus #200 sieve)versus depth for the SPTs from DH9O. Figures A. 16 to A. 18 show measured wave tracesand energies calculated by the force-velocity (FV) and force (F2) integration methods forselected SPT blows at 36.3, 42.4 and 48.5 m depths, respectively, from DH9O. The seconddrill hole, DH92, was done on January 9 to 10, 1992 using Associated Drilling’s Mayhew1000 drill rig (No. 2). A donut hammer and Mayhew rods (59 mm O.D./ 35 mm I.D.) withupset ends were used for the SPTs in DH92. Figure A. 19 summarizes the measured N-valueand energy ratio for this hole.Table A.2 presents characteristics of the two BPTs conducted at the Annacis test site. TheBPTs were conducted using Beck’s AP1000 Becker drill rig (No. 102).TABLE A.2Characteristics of BPTs conducted at Annacis test siteBPT Max. Fuel Casing Inner Becker DrillNo. Depth Setting O.D. Pipe Type - Rig No.(m) (mm) TypeBi 51.2 Full 170 Floating AP1000 - 102B2 42.2 Reduced 170 Floating AP1000 - 102Figures A.20 to A.24 present the following BPT data versus depth at the Annacis test site:measured blow count (Nb), peak bounce-chamber pressure (BP), maximum transferredenergy (ENTHRU), peak or maximum force (FMX) and maximum velocity (VMX).138TOWER 5/4, DELTAFigure A.25 shows the location plan for all the test holes carried out by FoundexExplorations Ltd. and Klohn Leonoff Ltd. as part of their IRAP funded Becker researchstudy at the Delta test site. As shown, a total of three CPTs, two drill holes with SPTs andten BPTs was conducted. Figures A.26 to A.28 show data for CPT91-l, CPT91-2 andCPT91-3, respectively. The CPTs were performed using a Geotech 10 cm2 cone totermination depths from 49 to 58 m.The drill holes were carried out using Foundex’s Simco 5000 drill rig. The SPTs were donewith an automatic trip hammer, with AW rods for tests to 15 m depth and with NQ rods(70 mm O.D./ 60 mm I.D.) for deeper tests. Note that dynamic measurements were notperformed on all the SPTs conducted in DH91-l. Figure A.29 summarizes results of theSPT energy measurements.The BPTs were carried out using Foundex’s HAV 180 Becker rig under full combustioncondition. Only six of the ten BPTs were monitored with the pile driving analyzer and someof these were only partially or intermittently monitored. Table A.3 summarizescharacteristics of these six BPTs. Figure A.30 shows dimensions of the Foundex oversizedbits used with the mud-injection technique, referred to as the Foundex Becker penetrationtest (FBPT).TABLE A.3Characteristics of BPTs conducted at Delta test siteBPT Max. Toe Shaft Inner Type of BPTNo. Depth O.D. O.D. Pipe(m) (mm) (mm) Type2 52.7 140 140 Fixed Conventional4 38.4 170 140 Fixed Mud-injection5 50.3 170 140 Fixed Mud-injection7 48.5 170 170 Floating Conventional8 43.0 220 170 Floating Mud-injection10 50.9 170 170 Floating ConventionalFigures A.31 and A.32 show the measured blow counts (Nb) versus depth for the six BPTs,while the energy data are presented in Figs A.33 and A.34. Finally, Figs. A.35 to A.42show measured BPT stress waves of representative blows from the Delta test site.139APPENDIX A - LIST OF FIGURESFig. A. 1 Site plan showing research sitesFig. A.2 Test hole location plan, Richmond test siteFig. A.3 CPT91-0l data, RichmondFig. A.4 CPT91-02 data, RichmondFig. A.5 CPT91-03 data, RichmondFig. A.6 SPT automatic trip hammerFig. A.7 SPT energy data for DH91-0l, RichmondFig. A.8 SPT energy data for DH91-02, RichmondFig. A.9 BPT blow count (Nb) vs depth, RichmondFig. A. 10 Peak bounce-chamber pressure (BP) vs depth, RichmondFig. A. 11 BPT ENTITRU vs depth, RichmondFig. A. 12 Test hole location plan, Annacis test siteFig. A. 13 CPT data, Annacis test siteFig. A. 14 SPT N and energy ratio for DM90, AnnacisFig. A. 15 SPT N60, mean grain size and % fines for DH9O, AnnacisFig. A.16 SPT wave traces DH9O @ 119 ft (36.3 m), AnnacisFig. A. 17 SPT wave traces DM90 @ 139 ft (42.4 m), AnnacisFig. A. 18 SPT wave traces DM90 @ 159 ft (48.5 m), AnnacisFig. A. 19 SPT N and energy ratio for DH92, AnnacisFig. A.20 BPT blow count (Nb) vs depth, AnnacisFig. A.21 Peak bounce-chamber pressure (BP) vs depth, AnnacisFig. A.22 BPT ENTHRU vs depth, AnnacisFig. A.23 BPT maximum force vs depth, AnnacisFig. A.24 BPT maximum velocity vs depth, AnnacisFig. A.25 Test hole location plan, Delta test site (from Yan and Wightman, 1992)Fig. A.26 CPT91-l data, DeltaFig. A.27 CPT91-2 data, DeltaFig. A.28 CPT91-3 data, DeltaFig. A.29 SPT maximum velocity, peak force and energy data for DH91-1, DeltaFig. A.30 Foundex oversized bits with mud-injection system(from Yan and Wightman, 1992)Fig. A.31 BPT blow count vs depth for BPT2, BPT7 and BPT1O, DeltaFig. A.32 BPT blow count vs depth for FBPT4, FBPT5 and FBPT8, DeltaFig. A.33 ENTHRU vs depth for BPT2, BPT7 and BPT1O, DeltaFig. A.34 ENTHRU vs depth for FBPT4, FBPT5 and FBPT8, DeltaFig. A.35 Wave traces from BPT2 @ 49 and 172 ft, DeltaFig. A.36 Wave traces from FBPT4 86 and 123 ft, DeltaFig. A.37 Wave traces from FBPT5 @ 101 and 139 ft, DeltaFig. A.38 Wave traces from FBPT5 @ 156 and 160 ft, DeltaFig. A.39 Wave traces from BPT7 @ 111 and 157 ft, DeltaFig. A.40 Wave traces from FBPT8 67 and 131 ft, DeltaFig. A.41 Wave traces from BPT1O @ 36.5 and 61.5 ft, DeltaFig. A.42 Wave traces from BPT1O @ 99.5 ft on initial driving and@ 99 ft on redriving, Delta140_____________________________Fi,6SER DEt_1,8SITE 1 — McDONALD’S FARM, SEA ISLANDSITE 2 — KWANTLEN COLLEGE, RICHMONDSITE 3 — FRASER BRIDGE. ANNACIS ISLANDSITE 4 — TOWER 5/4, DELTAFig. A.1 Site plan showing research sites141SEAISLAND -.STRAITOFGEORGIA( LULU ISLAND - ANNACIS10kmCANADA____U.S.A.0Fig. A.2TEST LOCATION PLAN, RICHMOND TEST SITEimTest hole location plan, Richmond test siteICPT91-O1DH91-02BPT4 BPT3II IIDH91-O1-CPT91-02)BPT5BPT 1CPT91-03BPT2——142DEPTH(metres)w P1—,-I-CD -,c,U,- m (I)CI)U,1 P1 m(1)P1‘1g2J1C)—--I‘1IzIi-I-I—i-n-IU)1-4(IC)—..ro-iLi)C))II-Ic3C)-t’-I0)D-CDLII2--n-Di-rnrn-i m C)O IC-)C)rn-‘I\)10IiI--)C)r’_)—C)C)C)I•IIr)IIICl)—U)IU)IU)IU)1-40).-i-II,—.I-1CDr1C)C)•-<•IIFig. A.4230CPT91-02 data, RichmondFRICTION RATIOQt/Fs=Rf (%)O 2.50102030CONE BEARING STRESSQt (bar)0 250SLEEVE FRICTIONFs (bar)00102010U)C.)C4)Ci60BEHIND TIP ppU2(rn.af water)-5 4501020 IINTERPRETEDPROFILE0SAND- _s.i1i:V_ -10SAND20SILT3030144(-i)C-)rnrOJ rn—fl) )G)(I)-I:o rn (I)(I)U)I rn9,rnU)- rn-‘1QJ—)C-)—-I—CC)-nC-I-‘—C)U)Dx1-I,:ijLflID)IDrrnBI-CCD-b—Iz oJ-DCl--U)Ln2•UJ0-Iornc133T1D—‘33i-rnrn—Irn CDDEPTH(nietres)O I() C)-C)I-UI CC)I-U—:.:I,56’/2”Fig. A.6 SPT automatic trip hammerDLER SPROCKET- 4”øHYDRAUUC CHAIN DRIVEWITH CAMSDRIVER SPROCKET- 4”øHYDRAULIC MOTORSPRINGAW ROD-3V21’ O.D.134” O.D.I ‘4” I.D.13‘2146ENERGY RATIO (%)O 10 20 30 40 50 60 70 80 90 100I I ii I I II I I ii I I II I i i ii ii10.20306O7080LFig. A.7 SPT energy data for DH91-O1, Richmond147ENERGY RA11O (%)0 10 20 30 40 50 60 70 80 90 1001o20:3Q:40Uw -5060:70-80 I IFig. A.8 SPT energy data for DH91-02, Richmond148DEPTH(H)0(0(XiCM(i-00000000000ItiiiiiiliiiiiiIIiII111111III1111111111liiIIIIIIIIIIItiilII1111111111(11th11111(111IIIEDI:IJwwtu-U-U-ti-U-UCD(0CD(0CDIIII00000— 0 0‘Il1 £111IIV“I’1% II111’I’IiI IjIi III”.Il’‘I0:0-‘J-o : : :0 :0 : : :0 coCl)p9 to 0 C-)0 C z —1 z 0111ll.iIII1I1II1?I,ItI’DEPTH(ft)0 0cocx01j’J-000000000IIIIiJJIIIILLLIIILLLLLLLIiiIIjjiLILELLLLIi_UJUJiiIIJJJJLIILLLIJLLIIIIIiiiI111111LLLIJI:rDcowww-±-IH-I-1IDCDIDCDID0111111C C In p.1 In CCIIII00000•0w-0 C C) >-w P10-D P1-U)r\)U) C Iii4Q3 -oc3).03I’jiI’IIfIllI$__I1/1/\I‘.1/‘I/f——‘/•0DEPTH(ft)-s oCo-CMIJ-000000000011111IIiiiiiiiiiIIiiiiitIIIIiliiIIIIII11111111iiiiiiiiliiiiiiiiIIIIIIiiIIIcoc-0-0-0-U-U(0(0(0(0(0IIII00000Cfl4(MJ—0I’ /E0---S-o.0m•z•-I0 0 0)‘I‘4TEST LOCATION PLAN, ANNACIS TEST SITEFig. A.12 Test hole location plan, Annacis test siteIfIIACPT1CC)2.5 mBPT-B 1DH92DH9O-1B PT-B 2152DEPTH(metres)C-)maJ m0)U)- m U)(I)U•)I mU)< m0)‘—4)C-)—-4‘--4‘1-r—C-)-n--ILi)4-4ii-b—I—1—ft)m ‘-4a -4’-1: 0)-D4-’-ft)4_n-)-fl-1(D-n-flrmrn—Irn EZJO (‘1 Cf) CDUI91’)03)-f)DSPT N (bpf) SPT ENERGY RATIO (%)o 20 40 60 0 20 40 60 80 1000_iitiiiiiiIiiiii,iIiiiiiii —____________________________- D D- C C- C 020— 0- C40 —- C C60— C 0- C80— C0 0100— 0- C120— C C- C C140— 0 C160—C CANNACIS DH9O ANNACS DH9O180— —Fig. A.14 SPT N and energy ratio for DH9O, Annacis154N60 MEAN GRAIN SIZE, D50 % MINUS #200 SIEVE0 20 40 600.0 0.2 0.4 0.6 0 5 10 15 200- 11111 I I — I ii 11111______________SILT10152025I.0w30354045SILT50— —__________________—__ __ _Fig. A.15 SPT N60, mean grain size and % fines for DH9O, Annacis155cn0-xC-)uJ>0LLizLiJANNACIS NORTH PIER, 6H1, 119FT, BLOW16Fig. A.16 SPT wave traces DH9O @ 119 ft (36.3 m), Annacis15640.030.020.0 -10.0 -—---- v*EA/cForce0.0—10.00.350.300.250.200.150.100.050.00I I I I I I I I I I I I I I I I I I I I I0.0 5.0 10.0 15.0 20.0 25.0 30.0I I I 1111 III till l 1 I I I0.0 5.0 10.0 15.0 20.0 25.0 30.0TIME (ms)ANNACIS NORTH PIER, BH1, l3gFr, BLOW740.0 —Force- - -- v*EA/c30.0 —Co -l:‘s— 20.0 —C—) Il,‘< 10.0E> .L 00—10.0 I I I I I I I I I I I I I I I0.0 5.0 10.0 15.0 20.0 25.0 30.00.35 —0.30‘4-0 EE =____0 05 - En —>-C-).10Li.J 0z000 — I I I I I I I I I I I I I I I I I I I0.0 5.0 10.0 15.0 20.0 25.0 30.0TIME (ms)Fig. A.17 SPT wave traces DH9O @ 139 ft (42.4 m), Annacis1570.350.30;0.150.100.050.00ANNACIS NORTH PIER, BH1, 159FT, BLOW4Fig. A.18 SPT wave traces DH9O @ 159 ft (48.5 m), Annacis15840.0 -30.0 -20.0-E10.0 -U,0.C-)UJ>1iForce%---- V*EA/C- . -0.0—10.00.0I I I I I I I I I I I I I I I I I I I5.0 10.0 15.0 20.0 25.0 30.00.0I II I I I I I I II I I I I5.0 10.0 15.0 20.0 25.0 30.0TIME (ms)SPT N (bpf) SPT ENERGY RATIO ()o 20 40 60 0 20 40 60 80 1000_IHII —_________________- 0 0- 0 0-o20- o 0- 0 0- 0 0- 0 040- o 0- 0 0- 0 060- 0 0‘4-=- 0 0F—J100- 00 0120 —140 -160—ANNACIS DH92 ANNACIS DH92180- —_ __Fig. A.19 SPT N and energy ratio for DH92, Annacis159MEASURED BLOWOQUNT, Nb (bpf)0 50 100 150 200 250 300- 350 400I I I I I I I I I I I I I I I I10= ,-ANNACIS NORTH PIER20-____BPT 91—ElBPT 91—B2‘S40-50-60-80-I,4- - -90100-110=120—130= -1 40 -150-1 60 -170-180-Fig. A.20 BPT blow count (Nb) vs depth, Annacis160BOUNCE CHAMBER PRESSURE, BP (psi)0 2 4 6 8 10 12 14 16 18 200— ‘ I I I I iI10-20-5Q: - I60:70-80 --120—1 30 =140- ANNACIS NORTH PIERBPT 91—81150— BPT 91—821 60 -170-180- -Fig. A.21 Peak bounce-chamber pressure (BP) vs depth, Annacis161DEPTH(ft)-U > P1(Z0-4 C-..J0>01-UIt)-0(0at--Jat(ii4(.1t’J00000000000000000liiiIiiiIillIiiiiIiiiiliiIiiiilliii11111111I111111tiiiiiiiliiiIiliii00tillA I’,‘I’:hI,Is,II0 0 “3 0 EQ •01cucx-4--I(0(0cucriz z > C-)(-I)z 0 -I 1J P10)PDA MAX FORCE (kip)0 20 40 60 80 100 120 140 160 1800— liii! till,ic20—50—60 - - - - -80 =‘1-9Q110-120- --130- -.140- ANNACIS NORTH PIER150- BPT 91—81BPT 91—82160-170—180:Fig. A.23 BPT maximum force vs depth, Annacis163DEPTH(ft)rd)cow00—--1> z z > 0 (I-)(1\)-00000iiiiiiliiicoJco(ii400000IIIII,IIIIIIIIicococo(n4(,O-000000000iiiIiiilliiiIiiiiiiiiIiiiiiiiliiiiiiiiitii0z 0cocococa-oa’ a’aaaa._I‘,•1’a’ a’a’IaI•IIaaa’aaI’,‘I0-tJ-o-40-(31>-><-P1-0 a--h0FOUNDEX BECKER IRAP RESEARCH SITETEST LOCATIONSBPT66R1 0(R) BPT86FO81 in = lOftj-0DH91 -1CPT91-2 BPT55RO2-EDH91-21 0BPT66FO1 BPT66SO6LEGEND- Becker Penetration Testse.g. BPT86FO8(1) (2) (3)(1) -tip diameter (inch x 0.1)(2) - sleeve/friction code:R = no oversize shoeS = oversize shoe ‘dry’F = oversize shoe plus mud flush(3) - test numberFig. A.25 Test hole location plan, Delta test site (from Yan and Wightman, 1992)L0 BPT66RO7BPT86FO9 CPT91-1[ BPT66SO3 BPT66FO4LBPT66FO5I165DEPTH(metres)C-,C)mrO1 m0) -0 U)— m U)U,U)C m m in—‘-IJ3oJ—)C)‘—4C)‘1)-t-I—I‘1—ILi)1ItC)— •I—1 C)CornC)C)—I—Di0—CDC)C)--0-I rn‘i-I,I-rnrn—Iin C)a’C CCoC)C)U)C7_ICon--CoDC)C)C)cjU)c-I-3 0)wCDU)‘(i_Ic-I-i-I-‘-4—.I-C)C—IC)CD—CciU)r’-Ii)Iiic3-i—0) )U)U-)—Im C/)Cr)U-)I m1111U)- nl-‘1Ii)I-i-3C_)—-4-4ci10m—r i-i—10)-uI—CD- -t:iC)—0mrmm ii;DEPTH(metres)0)C)0”10 ciC9‘1-4 C-)—I1-4ci—4-4ciP3-10C)ciC)C)0)0)IU-)1’U))i1-4>-.-.1-U1—1ciC)CD—‘1-t-I-Ic-)‘i—ILflI-IUIcrm—-h-1DiD‘-I—CD •.,-44-4XIrn-i rn 1=JDEPTH(metres)C-]C-)4-’ 001’-) CDC-)cD rnCDrncTI-4Di-,U)U)—Im (I) Cl)(i-i>I—CDrn‘in]U)-< CR-]1Di4-4-3(_)-4C.)CDcii-CUCDCDCDCU)I-3 DiLi)DiCDU)Ct4—4)>--I-I—.1II—CD—•—1MEAN VMX (f/s) MEAN FMX (kip) MEAN ENERGY ()0 5 10 15 20 0 10 20 30 40 50 0 20 40 60 O 100I I I I liii iii iii Ii ii I I I ii I I I I I IioH20— - -30— - ---F- -LU - -40=AWRodsNQRods60-—=70- =_________________-_________________Fig. A.29 SPT maximum velocity, peak force and energy data for DH91-1, Delta169STANDARD PLUGGEDBIT BECKER CASINGBPT 86F BPT 66FSKETCH OF FOUNDEX OVERSIZEDWiTH MUD INJECTIONBITSFig. A.30 Foundex oversized bits with mud-injection system(from Yan and Wightman, 1992)5/“ /84000000000-rL-—-J5 1/a”r—4ROWSHOLES,OF INJECTION/“ DIA.1 6”00000000J-22-170MEASURED BLOWCOUNT, Nb (bpf)0 20 40 60 80 100 120 140 160 180 2000— 11111111 Ii H 11111 III iiil II 11111111 HIl 111111 II II 111tH H iii him Hil I IIIHIhH 111111TOWER 5/4 BECKER RESEARCH10- FOUNDEX EXPLORATIONS LTD.- —— BPT2: Regular 5.520= BPT7: Regular 6.6-BPT1O: Regular 6.630- / ,- ‘-.\50- — --- —60=\ ‘- -,— ‘:—7--80-—S --5,•—5‘—S •90-•çF—0_S • —S s_S -w - --,-c100: ç110_120-)--IJ’J= /- L.5’140- —150-160- —S170—1 80:Fig. A.31 BPT blow count vs depth for BPT2, BPT7 and BPT1O, Delta171I— •‘•‘,‘ 1I —I —S •%— —__SJS, __\1 ,‘_. r—- - —.——S‘S.—180-Fig. A.32 BPT blow count vs depth for FBPT4, FBPT5 and FBPT8, DeltaMEASURED0 10 20 30 40I I I I I I I iLII I I LLJILLBLOWCOUNT,50 60I I I I INb (bpf)70 80 90 100I I I II I I i i i i I i IIITOWER 5/4 BECKER RESEARCHFOUNDEX EXPLORATIONS LTD.FBPT4: Mudded 6.6 ToeFBPT5: Mudded 6.6 Toe- —— FBPT8: Mudded 8.6 Toe010—20 —40 =50:60 —70:80 =‘Ic 100110-1 20 -130-1 401 501 601 70 -172ENTHRU (%) ENTHRU (%) ENTHRU (%)0 10 20 30 40 50 0 10 20 30 40 50 0 10 20 30 40 500— iiii I iii I— Ii I ii iii iiil iii — ii iiil I iii iii I10—20 — -30 — -.40— -—.60-• a70- -80- -90‘4-1007LU 110- -160- =• -170- -Initial180 = •.a..RedriveTOWER 5/4 TOWER 5/4 TOWER 5 -“4190— BPT55RO2 6PT66R07 BPT66RO200--_________________=_____Fig. A.33 ENTHRU vs depth for BPT2, BPT7 and BPT1O, Delta173ENTHRU (%) ENTHRU (%) ENTHRU (%)0 10 20 30 40 50 0 10 20 30 40 50 0 10 20 30 40 50_IIIIIHI!IHIIIIIHIIIII _ittIIIHiIIIIIIiHIfiIIi- -20- - -40- - -50- - -60- - -70- - -80— - -90— - -100j 7.110- -- )120— - -130— - -140 - - -150— — -160— — -170— — -180— — -TOWER 5/4 : TOWER 5/4 TOWER 5/4190- BPT66FO4 BPT66FO5 BPT86FOS200- —_________________-________Fig. A.34 ENTHRU vs depth for FBPT4, FBPT5 and FBPT8, Delta174TOWER 5/4, BPT55RO2, 49ft -ft/s Fcr ForceB. ___V1ccity: 40 m0 1 L/ cTOWER 5/4, BPT55RO2, 172ftFt/s Force FOrCG___V1ocity- 2000 10 SO m s10 L/cNFig. A.35 Wave traces from BPT2 @ 49 and 172 ft, Delta175- TOWER 5/4, BPT66FO4, 86E‘Ft/s Force Fcrc100V1ocityV\J JTOWER 5/4, BPT66FO4, 123ftft/s Fcrc Forcea V1ocity- 100o 10 50 L/c\ /Fig. A.36 Wave traces from FBPT4 @ 86 and 123 ft, Delta176TOWER 5/4, BPT66FO5, tO1fFt/s Force Fcrc___V1coity- 100I 50 m so “ 1D 01 /IfiTOWER 5/4, BPT66FO5, 139fcFt/s Fcrc ForceS.. ___V1ocity- 1004.m s0 10 120 . i‘0 1 L/c//Fig. A.37 Wave traces from FBPT5 @101 and 139 ft, Delta177TOWER 5/4, BPT6ÔFO5, l5ôEtst/s Force Force:LSLZC 1 \ /TOWER 5/4, BPT66FO5 l6Ofcct/s Force FcroS ___V1ccit100I/’Fig. A.38 Wave traces from FBPT5 @ 156 and 160 ft, Delta178TOWER 5/4, BFT66RO7, ltlEtft/s Force8., VQlocity- 1004-C 10 20JRJtJ 50 rnsC 1 p’ L/cTOWER 5/4, BPT66RO7, 157ftft/s Force Force1E __V1ocity- 300:m1L/cICN—__,_IFig. A.39 Wave traces from BPT7 @ 111 and 157 ft, Delta179TOWER 5/a, BPT86FO8, 67Ecst/s Fcrc_______Fcrc6. V1ocity100450 m s0 20\IQ j I1 ‘-__-_“17 L/c/tFt/s FcrcG TOWER 5/4, BPT86FOS, 131ft Force8.. _.._V1ccity- 1004. \I 50 ms0 100 L/c/\ /Fig. A.40 Wave traces from FBPT8 @ 67 and 131 ft, Delta180TOWER 5/4, BPT66R1O, 36.SftFt/s Fcrc_______Forc28.—_V1ocity- 1004. 1ilO \ 40 500 1 L / cTOWER 5/4, 8PT66R10, 61.5ft Fcrcft/s Force_____VQlocitySD ms0 -‘ / L/cI ‘t HA:dVFig. A.41 Wave traces from BPT1O @ 36.5 and 61.5 ft, Delta181Ft/s Forc. TOWER-5/4, BPT66R1O, 99.5ft_______FcrcV1ocity50 mIlD- -‘- L/c‘0 1 /TOWER 5/4, BPT66R1O, 99ft RedriveFt/s FQrCG8.. __.V1ocity- 1001020 50 m s10 ii L/c— ,‘-Fig. A.42 Wave traces from BPT1O @ 99.5 ft on initial driving and@ 99 ft on redriving, Delta182APPENDIX BRESULTS OF CAPWAP ANALYSES OF BPT, ANNACIS TEST SITEbyGOBLE RAUSCHE LIKINS AND ASSOCIATES, INC.Seattle, Washington183Goble Rausche Likins & Associates, Inc.ANNACIS IS., BPT—91—B1, 30 FT, 8/30/91 04/20/93Blow No. 248Final CAPWAP Capacity: Ru 34.0, Skin 27.0, Toe 7.0 kipsAverage Skin Values 6.8Toe 7.0Soil Model Parameters/ExtensionsCase DampingSoil Plug Weight (kips)Goble Rausche Likins & Associates,ANNACIS IS., BPT—91—B1, 30 FT, 8/30/91Blow No. 248Depth Area E-Modulus. ft in2 kips/in21 .00 12.30 29948.02 41.70 12.30 29948.0Toe Area (ft2) .238Segmnt Depth B.G. ImpedanceNo. feet kips/ft/sPile Damping (%).56 .156Spec. Weight Circumf.kips/ft3 ft1.0, Time Incr (ms) .207, Wave Speed (ft/s) 16796.1Soil Depth Depth Ru Sum of Ru Unit Resist. Smith QuakeSgmnt Below Below Up Down w. Respect to DampingNo. Gages Grade Depth Areaft ft kips kips kips kips/ft kips/f2 s/ft inch34.01 20.9 9.1 6.5 27.5 6.5 .94 .54 .156 .0702 27.8 16.1 7.5 20.0 14.0 1.07 .62 .156 .0703 34.8 23.0 8.4 11.6 22.4 1.21 .70 .156 .0704 41.7 30.0 4.7 7.0 27.0 .67 .39 .156 .070.90 .07029.22 .111 .150Skin Toe.193 .035.10Inc.04/20/93PILE PROFILE AND PILE MODEL.492.4921.7281.7281 3.48 21.93 .0012 41.70 21.93 .00Imp. Change T. Slack C. Slack Circumf.% inch inch feet.000 .000 1.728.000 .000 1.728184Goble Rausche Likins & Associates, Inc.ANNACIS IS., BPT—91—B]., 30 TI’, 8/30/91 04/20/93Blow No. 248EXTREMA TABLEPile Depth max. mm. max. max. max. max. max.Sgmnt Below Force Force Comp. Tension Trnsfd. Veloc. Displ.No. Gages Stress Stress Energyft kips kips kips/in2 kips/in2 kips-ft ft/s in1 3.5 129.4 —10.1 10.52 —.82 3.25 5.6 .7142 7.0 131.2 —15.7 10.67 —1.27 3.22 5.5 .7403 10.4 131.5 —6.1 10.69 —.49 3.21 5.9 .7404 13.9 132.1 —6.4 10.74 —.52 3.20 6.0 .7405 17.4 134.0 —5.5 10.90 —.44 3.19 6.2 .7306 20.9 135.1 —2.8 10.98 —.23 3.19 6.5 .7307 24.3 125.7 —8.4 10.22 —.68 2.62 6.5 .7309 31.3 115.6 —5.7 9.40 —.47 1.96 7.1 .73010 34.8 114.]. .0 9.28 .00 1.95 7.0 .73011 38.2 90.2 —3.1 7.34 —.25 1.20 6.9 .73012 41.7 51.7 .0 4.21 .00 .55 8.1 .730Absolute 20.9 10.99 (T 21.7 ms)7.0 —1.27 (T= 33.3 ms)ANNACIS IS., BPT—91—B1, 30 FT, 8/30/91Case Method Capacity Results3=0.0 J=0.1 J=0.2 J=0.3 3=0.4 J=0.5 3=0.6 3=0.7 J=0.8 3=0.9RS]. 112. 98. 83. 69. 55. 41. 27. 13. 0. 0.RMX 112. 98. 83. 69. 59. 54. 50. 46. 41. 37.RSU 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.RA A2 W 29. 24. 0.Current CAPWAP Ru = 34.0; Corresponding J(Rs) = .55; J(Rx) = 1.00VMAX VFIN V1*Z Fl FMAX DMAX DFIN EMAX EFIN R HF R EN5.65 .44 123.8 129.1 129.4 .714 .676 3.3 3.2 60.7 58.1185Goble Pausc[e Likns Associates. Inc.ANNACIS IS., BPT—91—Bit, 30 FT, 6/30/91Blow 24B 04/20/93Load in kps0 20 40 60 60—Top Movement rn inCh_______For MsdVel Med100kips500-50100kps500—50.40• 801 .201 .60msL/c______P3]e TopBottomRut = 34.0 kipsRsk 27.0 kipsPta = 7.0 kipsDy = . 19 inchDmx = .77 inchSkin ResistanceDistributionBkips100Pile Forces at Rut186Gobie Rausche Liking & Associates, Inc.ANNACIS IS., BPT—91—Bl, 40 FT, 8/30/91 04/21/93Blow No. 472Final CAPWAP Capacity: Ru 45.0, Skin 33.0, Tee 12.0 kipsAverage Skin Values 5.5 .82 .48 .091 .060Toe 12.0 52.15 .173 .050Soil Model Parameters/ExtensionsCase DampingUnloading LevelSoil Plug WeightSkin Toe.137 .0943014Soil Depth Depth Ru Sum of Ru Unit Resist. Smith QuakeSquint Below Below Up Down w. Respect to DampingNo. Gages Grade Depth Areaft ft kips kips kips kips/ft kips/f2 s/ft inch45.01 17.2 5.5 3.6 41.4 3.6 .52 .31 .091 .0602 24.1 12.4 4.6 36.8 8.2 .67 .40 .091 .0603 31.0 19.3 5.1 31.6 13.4 .75 .45 .091 .0604 37.9 26.2 6.3 25.3 19.6 .91 .55 .091 .0605 44.8 33.1 7.2 18.1 26.8 1.04 .62 .091 .0606 51.7 40.0 6.1 12.0 33.0 .89 .53 .091 .060(% of Ru)(kips)187Goble Rausche Likins & Associates, Inc.ANNACIS IS., BPT—91—Bl, 40 FT, 8/30/91 04/21/93Blow No. 472EXTREMA TABLEPile Depth max. miii. max. max. max. max. max.Sgmnt Below Force Force Comp. Tension Trnsfd. Veloc. Displ.No. Gages Stress Stress Energyft kips kips kips/in2 kips/in2 kips-ft ft/s in1 3.4 131.8 —7.2 10.71 —.59 2.28 5.8 .4722 6.9 130.1 —17.3 10.58 —1.41 2.29 5.6 .4603 10.3 130.5 —14.5 10.61 —1.18 2.29 5.6 .4505 17.2 132.5 —15.8 10.77 —1.29 2.28 5.5 .4506 20.7 128.6 —14.8 10.45 —1.21 2.12 5.4 .4508 27.6 124.8 —12.9 10.15 —1.04 1.90 5.5 .4509 31.0 126.1 —12.4 10.25 —1.00 1.90 5.7 .45011 37.9 122.1 —11.9 9.92 —.97 1.66 5.8 .45012 41.4 115.3 —10.2 9.38 —.83 1.37 6.3 .45014 48.3 100.8 —5.9 8.20 —.48 1.04 6.1 .44015 51.7 72.5 —4.6 5.90 —.37 .72 7.2 .447Absolute 17.2 10.77 (T 21.3 ins)6.9 —1.41 (T= 35.7 ins)ANACIS IS., BPT—91—Bl, 40 FT, 8/30/91Case Method Capacity ResultsJ=0.0 J=0.I. J=0.2 J=0.3 J=0.4 J=0.5 J=0.6 J=0.7 J=0.8 J=0.9RS1 107. 92. 78. 64. 50. 36. 22. 7. 0. 0.RMX 107. 92. 78. 68. 64. 60. 59. 58. 57. 56.RSU 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.RAA2W 23. 45. 0.Current CAPWAP Ru = 45.0; Corresponding J(Rs) = .43; J(Rx) = 1.00VMAX VFIN Vl*Z Fl FMAX DMAX DFIN EMAX EFIN R HF R EN5.78 —.03 126.R 121.6 131.8 .472 .318 2.3 2.3 60.7 51.7188Goble Rausche Likins £ Assocates. Inc.ANNACIS IS., BPT—91-B1, 40 FT. 8/30/91Blow 472 04/21/9340 ms) -ioiii’ Lit1_____ _____ _______Pi2e TopBottomRut 45.0 kipsRsk 33.0 kipsRto = 12.0 k2psDy = .12 inchDmx = .51 inch120.k i pm60._______For MmdFor CptFor MmdVel Mmd120kips0-60-60msL/c0Load in kips40 50 80.206080‘-4kipsSkin ResistanceDistributionTop Movement in inchPile Forces at Rut189Average Skin Values 5.0Soil Model Parameters/Extensions.42 .140Skin ToeCase DampingUnloading QuakeUnloading LevelSoil Plug Weight(% of loading quake)(‘ of Ru)(kips).224 .13625 10032.15EXTREMA TABLEAbsolute 20.620.67.36- .74(T 23.5 ma)(T= 43.5 IRs)Gable Rausche Likins & Associates, Inc.Annacis Is., BPT-91-B1, 50 FT, 8/30/91 04/16/92Blow No. 744Final CAPWAPC Capacity: Ru 45.0, Skin 35.0, Toe 10.0 kipa3.75.46.56.56.03.53.5Soil Depth Depth Ru Sum of Ru Unit Resist. Smith QuakeSgmnt Below Below Up Down w. Respect to DampingNo. Gages Grade Depth Areaft ft kipa kips kipa kips/ft kips/f2 s/ft inch1 20.6 8.9 .54 .31 .140 .0702 27.4 15.7 .78 .45 .140 .0703 34.3 22.6 .94 .55 .140 .0704 41.1 29.4 .94 .55 .140 .0705 48.0 36.3 .87 .50 .140 .0706 54.8 43.1 .51 .29 .140 .0707 61.7 50.0 .51 .29 .140 .070.70 .070Toe 10.0 42.02 .298 .05045.041.335.929.423.017.013.510.03.79.115.622.028.031.535.0Pile Depth sax. sin. sax. max. max. max. sax.Sgmnt Below Force Force Camp. Tension Trnsfd. Veloc. Diapl.No. Gages Stress Stress Energyft kips kips kips/in2 kips/in2 kips-ft ft/s in1 3.4 85.4 -3.0 6.94 -.24 1.39 3.4 .3183 10.3 86.8 -6.4 7.05 -.52 1.38 3.1 .3105 17.1 89.3 -8.4 7.26 -.68 1.37 3.1 .3007 24.0 86.9 -8.1 7.06 -.66 1.26 3.0 .3009 30.8 82.0 -7.1 6.66 - .58 1.10 2.8 .29011 37.7 74.6 -5.9 6.06 -.48 .92 3.1 .28012 41.1 74.6 -6.2 6.07 -.50 .92 3.2 .27014 48.0 65.7 -4.1 5.34 -.33 .74 3.6 .27016 54.8 58.3 -2.0 4.74 -.16 .57 3.6 .27018 61.7 38.3 -1.6 3.11 -.13 .38 3.7 .271190Goble Rauache Likins S. Associates, Inc.Annacia Ia., BPT-9l-Bl, 50 FT, 8/30/91 04/16/92Blow No. 744PILE PROFILE AND PILE MODELDepth Area E-Modulua Spec. Weight Circuaf.ft in2 kips/in2 kips/1t3 ft1 .00 12.30 29948.0 .492 1.7282 61.70 12.30 29948.0 .492 1.728Toe Area Cft2) .238Segant Depth B.G. Ispedance lap. Change T. Slack C. Slack Circuntf.No. feet kipa/ft/s inch inch feet1 3.43 21.93 .00 .000 .000 1.72818 61.70 21.93 .00 .000 .000 1.728Pile Daaping (‘c) 2.0, Tise Incr (as) .204, Wave Speed (ft/a) 16796.1Annecia Is., BPT-91-B1, 50 FT, 8/30/91Case Method Capacity Results3=0.0 J=0.1 J=0.2 J=0.3 3=0.4 J=0.5 3=0.6 J=0.7 3=0.8 3=0.9RS1 84. 78. 71. 64. 58. 51. 44. 38. 31. 24.RMX 84. 78. 71. 64. 58. 51. 44. 42. 41. 40.RSU 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.RA A2 W 39. 58. 0.Current CAPWAP Ru = 45.0; Corresponding J(Rs) = .59; J(Rx) = .59VMAX VFIN V1aZ Fl FMAX DHAX DFIN EMAX EFIN R HF R EN3.36 .00 73.7 77.1 85.4 .318 .254 1.4 1.4 51.1 38.4191Cable Rousche Likins Associates. Inc.Annaci Is.. BPT—91—B1. 50 FT. 8/30/91Blow 744 04/17/92_____For M.dV.1 M.d•0 1 2 V4 •576 7 •GFor M.dFor Cpt120ki p.fiBL/c—60 -møLbV.1 M.dV.1 Cpt......JP1, ... B.sO 1 2 3-\;Y6 7 B Lb8. 0fib.4.0..0—4. 0ILWI Skin Re.istonc.1111 Oistributio,(To. 10.0 hip.)Forc.s ot Rut100J192Goble Rausche Likins & Associates, Inc.ANNACIS IS., BPT—91—B1, 70 FT, 8/30/91 04/20/93Blow No. 530Final CAPWAP Capacity: Ru 57.0, Skin 42.2, Toe 14.8 kipsCase DampingUnloading QuakeUnloading LevelSoil Plug Weight(% of loading quake)(% of Ru)(Jcips)Skin Toe.296 .21589 1003010Toe Area (ft2) .238PILE PROFILE AND PILE MODELSegxnnt Depth B.G. Impedance Imp. Change T. Slack C. SlackNo. feet kips/ft/s inch inchPile Damping (%) 1.0, Time Incr (as) .207, Wave Speed (ft/s) 16463.5Soil Depth Depth Ru Sum of Ru Unit Resist. Smith QuakeSgmnt Below Below Up Down w. Respect to DampingNo. Gages Grade Depth Areaft ft kips kips kips kips/ft kips/f2 s/ft inch57 . 01 20.4 8.7 .4 56.5 .4 .06 .04 .157 .0552 27.2 15.5 .5 56.1 .9. .07 .04 .157 .0553 34.0 22.3 .7 55.4 1.6 .10 .06 .157 .0554 40.8 29.1 .7 54.7 2.2 .10 .06 .157 .0555 47.7 36.0 2.3 52.4 4.5 .34 .20 .157 .0556 54.5 42.8 5.8 46.7 10.3 .85 .49 .157 .0557 61.3 49.6 9.2 37.5 19.5 1.35 .78 .157 .0558 68.1 56.4 8.1 29.3 27.6 1.20 .69 .157 .0559 74.9 63.2 7.3 22.1 34.9 1.07 .62 .157 .05510 81.7 70.0 7.3 14.8 42.2 1.07 .62 .157 .0554.2 .60Average Skin ValuesToe 14 • 8Soil Model Parameters/Extensions.36 .157 .05562.07 .325 .200Depth Area E-Modulus Spec. Weight Circumf.ft in2 kips/in2 kips/ft3 ft1 .00 12.30 29349.0 .502 1.7282 81.70 12.30 29349.0 .502 1.7281 3.40 21.93 .00 .000 .000 1.72824 81.70 21.93 .00 .000 .000 1.728Circujaf.feet193Goble Rausche Likins & Associates, Inc.ANNACIS IS., BPT—9l—B1, 70 FT, 8/30/91 04/20/93Blow No. 530EXTREMA TABLEPile Depth max. mm. max. max. max. max. max.Sginnt Below Force Force Comp. Tension Trnsfd. Veloc. Dispi.No. Gages Stress Stress Energyft kips kips kips/in2 kips/in2 kips—ft ft/s in1 3.4 132.2 —8.9 10.75 —.72 2.31 5.8 .3822 6.8 134.6 —3.9 10.94 —.31 2.31 5.7 .3804 13.6 135.2 —5.3 10.99 —.43 2.30 5.6 .3706 20.4 136.0 —4.7 11.05 —.38 2.29 5.6 .3609 30.6 135.8 —4.7 11.04 —.39 2.23 5.4 .35011 37.4 135.7 —3.5 11.03 —.29 2.19 5.4 .35013 44.3 136.1 —6.3 11.06 —.51 2.15 5.3 .34016 54.5 136.7 —6.1 11.12 —.49 2.06 5.0 .33018 61.3 131.6 —5.2 10.70 —.42 1.84 4.8 .32021 71.5 107.7 .0 8.76 .00 1.24 5.2 .32023 78.3 91.7 .0 7.45 .00 .98 5.2 .31024 81.7 67.2 .0 5.46 .00 .64 6.2 .316Absolute 47.7 11.15 (T= 23.4 ms)3.4 —.72 (T= 30.8 ms)ANNACIS IS., BPT—91—B1, 70 FT, 8/30/91Case Method Capacity ResultsJ=0.0 J=0.1 J=0.2 3=0.3 J=0.4 J=0.5 J=0.6 3=0.7 J=0.8 3=0.9RS1 128. 118. 107. 97. 86. 76. 65. 55. 44. 34.RMX 128. 118. 107. 97. 86. 76. 65. 57. 53. 51.RSU 131. 121. 111. 101. 91. 80. 70. 60. 50. 40.RA A2 W 34. 71. 0.Current CAPWAP Ru = 57.0; Corresponding J(Rs) = .68; J(Rx) = .70VMAX VFIN V1*Z Fl FMAX DMAX DFIN EMAX EFIN R HF R EN5.80 .39 115.8 119.7 132.2 .382 .266 2.3 2.2 93.5 89.1194Gobe Rausche Lakins Associates, Inc.ANNACIS IS., BPT-91-Ba, 70 FT. 6/30/91Blow 530 04/20/93______For’ MsdFor’ Cot_______For MsdVel Msd120kiDs600-60120kips600—60.40• BOI .201 .60Load in kips0 20 40 60 80meL/cmeL/c_____Pale TopBottom57.0 kips.42.2 kps14.8 kips.34 nch.45 inch8.RutRskOto =Dy =DmxSkin ResistanceDistributionTop Movement in inchPile Forces at RutI00195Goble Rausche Likins & Associates, Inc.Annacis Is., BPT-9l-Bl, 140 FT, 8/30/91 04/17/92Blow No. 1749Final CAPWAPC Capacity: Ru 105.0, Skin 80.0, Toe 25.0 kipsSoil Depth Depth Ru Sum of Ru Unit Resist. Smith QuakeSgmnt Below Below Up Down w. Respect to DampingNo. Gages Grade Depth Areaft ft kips kips kips kips/ft kips/f2 s/ft inch105 .01 19.8 8.1 .7 104.3 .7 .11 .06 .140 .0752 26.4 14.7 1.2 103.1 1.9 .18 .11 .140 .0753 33.0 21.3 1.5 101.6 3.4 .23 .13 .140 .0754 39.6 27.9 1.8 99.8 5.2 .27 .16 .140 .0755 46.2 34.5 1.4 98.3 6.7 .21 .12 .140 .0756 52.8 41.1 1.4 96.9 8.1 .21 .12 .140 .0757 59.4 47.7 23 94.7 10.3 .34 .20 .140 .0758 66.0 54.3 2.9 91.8 13.2 .44 .25 .140 .0759 72.6 60.9 2.5 89.3 15.7 .38 .22 .140 .07510 79.1 67.4 2.0 87.2 17.8 .31 .18 .140 .07511 85.7 74.0 2.0 85.2 19.8 .31 .18 .140 .07512 92.3 80.6 2.6 82.6 22.4 .39 .23 .140 .07513 98.9 87.2 4.0 78.6 26.4 .61 .35 .140 .07514 105.5 93.8 1.8 76.8 28.2 .27 .16 .140 .07515 112.1 100.4 1.5 75.3 29.7 .23 .13 .140 .07516 118.7 107.0 3.0 72.3 32.7 .46 .26 .140 .07517 125.3 113.6 5.8 66.5 38.5 .88 .51 .140 .07518 131.9 120.2 9.3 57.2 47.8 1.41 .82 .168 .07519 138.5 126.8 11.1 46.1 58.9 1.68 .97 .197 .07520 145.1 133.4 11.1 35.1 69.9 1.68 .97 .211 .07521 151.7 140.0 10.1 25.0 80.0 1.53 .88 .211 .070Average Skin Values 3.8 .57 .33 .170 .074Toe 25.0 105.00 .330 .075Soil Model Parameters/Extensions Skin ToeCase Damping .620 .376Unloading Quake (‘ of loading quake) 50 100Unloading Level (‘ of Ru) 30Soil Plug Weight (kipa) .20196Goble Rauache Likins & AssociateB, Inc.BPT-91-B1, 140 FT, 8/30/91Blow No. 1749EXTRENA TABLEAbsolute 26.498.99.97-1.59CT 23.2 ma)(T 50.5 *8)Annacia Is., 04/17/92Pile Depth max. mm. max. sax. max. max. max.Sgmnt Below Force Force Comp. Tension Trnafd. Veloc. Displ.No. Gages Stress Stress Energyft kips kips kips/in2 kips/mn2 kips-ft ft/s in1 3.3 115.2 -1.1 9.37 -.09 224 5.7 .3968 26.4 122.6 -8.7 9.97 -.71 2.16 5.2 .35013 42.9 118.4 -14.1 9.62 -1.14 1.96 5.0 .33017 56.1 116.5 -16.6 9.48 -1.35 1.82 4.8 .30022 72.6 112.7 -16.6 9.17 -1.35 1.59 4.6 .27027 89.0 103.3 -17.0 8.40 -1.38 1.34 4.5 .24031 102.2 100.0 -18.5 8.13 -1.51 1.14 4.1 .20036 118.7 100.7 -19.0 8.19 -1.54 1.00 3.8 .17040 131.9 99.0 -16.9 8.05 -1.37 .82 3.4 .14045 148.4 71.0 -13.0 5.78 -1.06 .42 3.0 .12046 151.7 64.4 -11.1 5.23 -.90 .32 3.4 .121197Goble Rauache Likins & Associates, Inc.Annacis Is.,, BPT-91-Bl, 140 FT, 8/30/91 04/17/92Blow Ne. 1749PILE PROFILE AND PILE MODELDepth Area E-Modulus Spec. Weight Circu,nf.ft in2 kipa/in2 kips/ft3 ft1 .00 12.30 29948.0 .492 1.7282 151.70 12.30 29948.0 .492 1.728Toe Area (ft2) .238Seginnt Depth B.G. Impedance isp. Change T. Slack C. Slack Circumf.No. feet kipa/ft/s inch inch feet1 3.30 21.93 .00 .000 .000 1.72822 72.55 19.93 -9.12 .000 .000 1.72823 75.85 21.93 .00 .000 .000 1.72829 95.64 18.93 -13.68 .000 .016 1.72830 98.93 19.93 -9.12 .000 .000 1.72831 102.23 21.93 .00 .000 .000 1.72846 151.70 21.93 .00 .000 .000 1.728Pile Damping (%) 2.0, Time Incr (ma) .196, Wave Speed (ft/a) 16796.1Annacis Is., BPT-91-B1, 140 FT, 8/30/91Case Method Capacity Results3=0.0 3=0.1 J=0.2 3=0.3 3=0.4 3=0.5 J=0.6 3=0.7 3=0.8 3=0.9RS1 155. 146. 138. 129. 121. 112. 104. 95. 87. 78.RNX 155. 146. 138. 129. 121. 112. 104. 95. 87. 78.RSU 165. 158. 151. 143. 136. 129. 121. 114. 107. 99.RA A2 W 10. 62. 0.Current CAPWAP Ru = 105.0; Corresponding 3(Rs) = .59; J(Rx) = .59VMAX VFIN V1*2 Fl FMAX DMAX DFIN EHAX EFIN R HF R EN5.75 -.40 126.0 113.2 115.2 .396 .065 2.2 1.9 119.9 176.2198ob1e Roucho Likiris AGsociotQa. Inc.Annocis Is., BPT—91—B1, 140 FT. 8/30/91Blow 1749 04/17/92...For MadFor Cpt—.For MadVol MadD18L/c_..._Vcl MadVol CptLI:8. 0ct/a4.0—4. 0)04-PilamaL/:Skin RaiatonaoDtmtribution(Too 25.0 kipa)Pilo Farcam at Rut199

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