Comparison of Rapid Load Test Analysis Techniques in Clay Soils
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 139, Issue 1
Abstract
Rapid load pile testing (RLT) techniques such as Statnamic were developed as an alternative to more frequently adopted static and dynamic tests. The existing unloading point method (UPM) for deriving equivalent static load-settlement behavior from rapid load tests seems to be adequate in coarse-grained soils but may result in poor prediction in clays and silts. To address these shortcomings, the UPM has been improved to reflect soil type, and new analysis techniques have been developed. To test the performance of the improved UPM and new analysis techniques, pile tests from two clay sites were analyzed. The first case study site was underlain by very to extremely high-plasticity Quaternary London clay, and the second site was underlain by low- to intermediate-plasticity matrix dominant glacial till. The best predictions of static equivalent load-settlement behavior for very-high-plasticity clay were obtained from a new analysis technique that incorporated a soil-specific rate effect parameter (selected on the basis of the clays’ plasticity index) that varied with pile settlement. In general, the UPM performed better for tests undertaken in the low- to intermediate-plasticity glacial till, as there is greater experience of RLT in these soils. The results of the study suggest that the development of analysis techniques would benefit greatly from tests in a wider variety of soil types. On the basis of the findings of this study, improvements to the UPM and Schmuker techniques are presented, which include pile settlement–dependent variation of the damping and rate effect parameters.
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Acknowledgments
The authors would like to thank Stent Foundations Limited for pile installation and static testing, ITC-Profound for Statnamic pile testing, and the RaPPER project partners. Pile testing was undertaken as part of the RaPPER project, which was partially funded by the Department for Business, Innovation and Skills, U.K.
References
Balderas-Meca, J. (2004). “Rate effects in rapid loading of clay soils.” Ph.D. thesis, Univ. of Sheffield, Sheffield, U.K.
Bond, A. J. (1989). “Behaviour of displacement piles in over-consolidated clays.” Ph.D. thesis, Imperial College, London.
Briaud, J-L., Ballouz, M. and Nasr, G. (2000). “Static capacity prediction by dynamic methods for three bored piles.” J. Geotech. Geoenviron. Eng., 126(7), 640–648.
Brown, D. A. (1994). “Evaluation of static capacity of deep foundations from Statnamic testing.” Geotech. Test. J., 17(4), 403–414.
Brown, M. J. (2004). “The rapid load testing of piles in fine grained soils.” Ph.D. thesis, Univ. of Sheffield, Sheffield, U.K.
Brown, M. J. (2008). “Recommendations for Statnamic use and interpretation of piles installed in clay.” Proc., Int. Seminar on Rapid Load Testing on Piles, CRC Press/Balkema, Leiden, Netherlands, 23–36.
Brown, M. J., and Hyde, A. F. L. (2008). “Rate effects from pile shaft resistance measurements.” Can. Geotech. J., 45(3), 425–431.
Brown, M. J., Hyde, A. F. L., and Anderson, W. F. (2006). “Analysis of a rapid load test on an instrumented bored pile in clay.” Geotechnique, 56(9), 627–638.
British Standards Institution (BSI). (1999). “Code of practice for site investigations.” BS5930:1999, London.
Crilly, M. S., Driscoll, R. M. C., and Chandler, R. J. (1992). “Seasonal ground and water movement observations from an expansive clay site in the UK.” Proc., 7th Int. Conf. on Expansive Soils, Texas Technical University Press, Lubbock, TX, 313–318.
Gudehus, G. (1981). Bodenmechanik, Enke, Stuttgart, Germany (in German).
Holeyman, A. E., Maertens, J., Huybrechts, N., and Legrand, C. (2000). “Results of an international pile dynamic testing prediction event.” Proc., 6th Int. Conf. on the Application of Stress Wave Theory to Piles, Balkema, Rotterdam, Netherlands, 725–732.
Institution of Civil Engineers. (2007). ICE specification for piling and embedded retaining walls, 2nd Ed., Thomas Telford, London.
Jardine, R. J. (1991). “The cyclic behaviour of large piles with special reference to offshore structures.” Cyclic loading of soils: From theory to design, Blackie, Glasgow, U.K., 174–245.
Lehane, B. M., and Jardine, R. J. (1994). “Displacement pile behaviour in glacial clay.” Can. Geotech. J., 31(1), 79–90.
Leinenkugel, H. J. (1976). Deformations- und festigkeitsverhalten bindiger erdstoffe, Univ. of Karlsruhe, Karlsruhe, Germany, 66 (in German).
Litkouthi, S., and Poskitt, T. J. (1980). “Damping constants for pile driveability calculations.” Geotechnique, 30(1), 77–86.
Lunne, T., Robertson, P. K., and Powell, J. J. M. (1997). Cone penetration testing in geotechnical practice, 1st Ed., Blackie, London.
Marsland, A., and Powell, J. J. M. (1979). “Evaluating the large scale properties of glacial clays for foundation design.” Proc., 2nd Int. Conf. on the Behaviour of Offshore Structures, Vol. 1, BHRA Fluid Engineering, Cranfield, U.K., 193–214.
Marsland, A., and Powell, J. J. M. (1980). “Cyclic load tests on 865 mm diameter plates in a stiff clay till.” Proc., Int. Symp. on Soils under Cyclic and Transient Loading, Balkema, Rotterdam, Netherlands, 837–847.
McVay, M. C., Kuo, C. L., and Guisinger, A. L. (2003). “Calibrating resistance factor in load and resistance factor design of Statnamic load testing.” Research. Rep. 4910-4504-823-12, Florida Department of Transportation, Tallahassee, FL.
Middendorp, P. (2000). “Statnamic the engineering of art.” Proc., 6th Int. Conf. on the Application of Stress Wave Theory to Piles, Balkema, Rotterdam, Netherlands, 551–562.
Middendorp, P., Beck, C., and Lambo, A. (2008). “Verification of Statnamic load testing with static load testing in a cohesive soil type in Germany.” Proc., 8th Int. Conf. on the Application of Stress Wave Theory to Piles, IOS Press, Amsterdam, Netherlands, 531–536.
Paikowsky, S. G. (2004). “Innovative load testing systems.” National Cooperative Highway Research Program, Research Rep. NCHRP 21-08, Transportation Research Board, Washington, DC.
Poskitt, T. J., and Leonard, C. (1982). “Effect of velocity on penetrometer resistance.” Proc., 2nd European Symp. on Penetration Testing, Balkema, Rotterdam, Netherlands, 331–336.
Powell, J. J. M., and Brown, M. J. (2006). “Statnamic pile testing for foundation re-use.” Proc., Int. Conf. on the Re-use of Foundations for Urban Sites, IHS BRE Press, Bracknell, U.K., 223–236.
Powell, J. J. M., and Butcher, A. P. (2003). “Characterisation of a glacial till at Cowden, Humberside.” Proc., Int. Conf. on the Characterisation and Engineering Properties of Natural Soils, Swets and Zeitlinger, Lisse, Netherlands, 983–1019.
Randolph, M. F., and Deeks, A. J. (1992). “Dynamic and static soil models for axial response.” Proc., 4th Int. Conf. on the Application of Stress Wave Theory to Piles, Balkema, Rotterdam, Netherlands, 3–14.
Schmuker, C. (2005). “Comparison of static load tests and Statnamic load test.” Diploma thesis, Biberach Univ., Biberach an der Riss, Germany (in German).
Skinner, H., Powell, J. J. M., Morris, J., and England, M. (2003). “Results from a piling trial on bored CFA and rotary displacement piles in stiff clay.” Proc., 1st Int. BGA Conf. on Foundations, Thomas Telford, London, 825–834.
Stokes, M., Mullins, G., Ealy, C. and Winters, D. (2008). “Statnamic damping coefficient: Numerical model approach.” J. Geotech. Geoenviron. Eng., 134(9), 1290–1298.
Triantafyllidis, T. (2001). “On application of the Hiley formula in driving long piles.” Geotechnique, 51(10), 891–895.
Weaver, T. J. and Rollins, K. M. (2010). “Reduction factor for the unloading point method at clay soil sites.” J. Geotech. Geoenviron. Eng., 136(4), 643–646.
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Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 139 • Issue 1 • January 2013
Pages: 152 - 161
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Jul 30, 2010
Accepted: Mar 19, 2012
Published online: Mar 21, 2012
Published in print: Jan 1, 2013
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