Shielding Piles from Downdrag in Consolidating Ground
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VIEW THE REPLYPublication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 139, Issue 6
Abstract
Negative skin friction (NSF) can induce an increased compressive force on piles, called dragload, and additional pile settlement caused by the downward pull of the soil, called downdrag. To investigate the efficiency of shielding effects on dragload and downdrag of piles, centrifuge tests have been carried out to study the shielding mechanisms created by installing sheet piles sleeves around an existing pile in consolidating ground. The effects of various shielded lengths have also been investigated. Comparisons between centrifuge test results and finite-element (FE) analyses are made and discussed. Based on centrifuge tests, it is clear that the shielding effect on the dragload decreases only gently with a decrease in the shielded length, whereas the shielding effect on the downdrag decreases exponentially with a decrease in the shielded length. Numerical simulations of the centrifuge model tests on the sleeved center piles reveal that the observed shielding effects on the center pile are attributed to the stress transfer from the consolidating soft soil to the sheet pile sleeve. As consolidation proceeds, the relatively stiff sheet piles sleeve hangs up the soil, leading to a significant reduction in the vertical and horizontal effective stresses in the soil and in the NSF on the center piles. The deeper the depth, the greater the hang-up effects. Thus, the shielding effect increases with the shielded length of the center pile. The reduction in the NSF on the center piles protected by the sheet pile sleeve is more significant than the reduction in the NSF from the sacrificial piles with the same shielded length.
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References
ABAQUS 6.12 [Computer software]. Providence, RI, SIMULIA.
Acar, Y. B., Avent, R., and Taha, M. R. (1994). “Downdrag on friction piles: A case history.” Proc., Settlement 94: Vertical and Horizontal Deformations of Foundations and Embankment, ASCE, New York, 40, 986–999.
Bolton, M. D. (1986). “The strength and dilatancy of sands.” Géotechnique, 36(1), 65–78.
Bjerrum, L., Johannessen, I. J., and Eide, O. (1969). “Reduction of negative skin friction on steel piles to rock.” Proc., 7th ICSMFE, Mexico, 2, 27–34.
Burland, J. (1973). “Shaft friction of piles in clay: A simple fundamental approach.” Ground Engng, 6(3), 30–42.
Cai, Z. Y. (2001). “A comprehensive study of state-dependent dilatancy and its application in shear band formation analysis.” Ph.D. thesis, Hong Kong Univ. of Science and Technology, Kowloon, Hong Kong.
Chow, Y. K., Chin, J. T., and Lee, S. L. (1990). “Negative skin friction on pile groups.” Int. J. Numer. Anal. Meth. Geomech., 14(2), 75–91.
Clegg, D. P. (1981). “Model piles in stiff clay.” Ph.D. thesis, Univ. of Cambridge, Cambridge, U.K.
Davisson, M. T. (1993). “Negative skin friction in piles and design decisions.” Proc., 3rd Int. Conf. Case Histories Geotechnical Engineering, St. Louis, 1793–1801.
Elmes, D. R. (1986). “Creep and viscosity in two kaolin clays.” Ph.D. thesis, Univ. of Cambridge, Cambridge, U.K.
Fannin, R. J. (1987). “Geogird reinforcement of granular layers on soft clay.” Ph.D. thesis, Univ. of Oxford, Oxford, U.K.
Fellenius, B. H. (1999). “Pile terminology.” 〈http://www.geoforum.com/info/pileinfo/terminology.asp〉 (Dec. 1, 2006).
Inoue, Y., Tamaoki, K., and Ogai, T. (1977). “Settlement of building due to pile downdrag.” Proc., 9th ICSMFE, Plenum Publishing Corporation, Berlin, 561–564.
Ishibashi, I. and Zhang, X. (1993). “Unified dynamic shear moduli and damping ratios of sand and clay.” Soils Founds, 33(1), 182–191.
Jamiolkowski, M., Ladd, C. C., Grmaine, J. T., and Lancellotta, R. (1985). “New developments in field and laboratory testing of soils.” Proc., 11th ICSMFE, Taylor & Francis Group, Oxford, U.K., 1, 57–153.
Johannessen, I. J. and Bjerrum, L. (1965). “Measurement of the compression of a steel pile to rock due to settlement of the surrounding clay.” Proc., 6th ICSMFE, Vol. 2, University of Toronto Press, Toronto, 261–264.
Kog, Y. C. (1987). “A case study of downdrag and axial load on timber piles in layered soil.” Proc., 5th Int. Geotech. Seminar, Singapore, 269–276.
Lam, S. Y. (2006). “Axial load, shielding and shape effects on negative skin friction.” MPhil thesis, Hong Kong Univ. of Science and Technology, Kowloon, Hong Kong.
Lam, S. Y., Ng, C. W. W., Leung, C. F., and Chan, S. H. (2009). “Centrifuge and numerical modelling of axial load effects on piles in consolidating ground.” Can. Geotech. J., 46(1), 10–24.
Lambe, T. W., Garlanger, J. E., and Leifer, S. A. (1974). “Prediction and field evaluation of downdrag forces on a single pile.” Research Rep. No. R74-27, Soils Publication 339, Dept. of Civil Engineering, Massachusetts Institute of Technology, Cambridge, MA.
Lee, C. J.and Chen, C. Z. (2002). Negative skin friction on grouped piles. Proc. Int. Conf. Physical Modelling in Geotechnics, St. John's, Newfoundland, Canada, 679–684.
Lee, C. J. and Ng, C. W. W. (2004). “Development of downdrag on piles and pile groups in consolidating soil.” J. Geotech. Geoenviron. Eng., 130(9), 905–914.
Mair, R. J. (1993). “Unwin Memorial Lecture 1992 developments in geotechnical engineering research: Application to tunnels and deep excavations.” Proc. Instn. Civ. Engrs, Institution of Civil Engineers, London, 97(1), 27–41.
Meyerhof, G. G. (1976). “Bearing capacity and settlement of pile foundations.” J. Geotech. Engng., 102(3), 197–227.
Mochtar, I. B. and Edil, T. B. (1988). “Shaft resistance of model pile in clay.” J. Geotech. Engrg. 114(11), 1227–1244.
Ng, C. W. W., Chan, S. H., and Lam, S. Y. (2005). “Centrifuge and numerical modeling of shielding effects on piles in consolidating soil. Recent developments of geotechnical engineering in soft ground.” Proc., 2nd China-Japan Geotechnical Symp., Shanghai, China, 7–19.
Ng, C. W. W., Poulos, H. G., Chan, V. S. H., Lam, S. S. Y., and Chan, G. C. Y. (2008). “Effects of tip location and shielding on piles in consolidating ground.” J. Geotech. Geoenviron. Eng, 134(9), 1245–1260.
Okabe, T. (1977). “Large negative friction and friction-free pile methods.” Proc., 9th ICSMFE, Plenum Publishing Corporation, Berlin, 679–682.
Poulos, H. G. and Davis, E. H. (1980). Pile foundation analysis and design. Wiley, New York.
Poulos, H. G. (1997). “Piles subjected to negative friction: A procedure for design.” Geotech. Engng., 28(1), 23–44.
Randolph, M. F. and Houlsby, G. T. (1984). “The limiting pressure on a circular pile loaded laterally in cohesive soil.” Géotechnique, 34(4), 613–623.
Randolph, M. F. and Wroth, C. P. (1981). “Application of the failure state in undrained simple shear to the shaft capacity of driven piles.” Géotechnique, 31(1), 143–157.
Stewart, D. P. and Randolph, M. F. (1991). “A new site investigation tool for the centrifuge.” Proc., Int. Conf. Centrifuge 1991, Balkema, Leiden, Netherlands, 531–538.
Teh, C. I. and Wong, K. S. (1995).“Analysis of downdrag on pile groups.” Géotechnique, 45(2), 191–207.
Wong, M. H. (2004). “Investigation of capacity, interactions and failure criteria of jacked pile groups in sand by centrifuge modelling.” MPhil thesis, Hong Kong Univ. of Science and Technology, Kowloon, Hong Kong.
Zeevaert, L. (1959). “Reduction of point bearing capacity of piles because of negative friction.” Proc., 1st Panamerican Conf. Soil Mechanical Foundation Engineering, 3, 1145–1152.
Zeevaert, L. (1973). Foundation engineering for difficult subsoil conditions. Van Nostrand Reinhold, Surry Hills, Australia, 353–373.
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Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 139 • Issue 6 • June 2013
Pages: 956 - 968
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Oct 4, 2011
Accepted: Jul 13, 2012
Published online: Jul 31, 2012
Published in print: Jun 1, 2013
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