Load distribution in large pile groups under static and dynamic loading
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Research on the action of pile groups in resisting lateral loading is usually based on analysis, field and centrifuge tests of small pile groups. The interaction between piles in these groups is modelled by modifying the lateral resistance p–y curves developed for a single pile using row dependent reduction factors or a group factor for the entire group to simulate the effect of soil–pile–soil interaction. The modifying factors for the p–y curves and the appropriate group factors for pile groups are based entirely on static tests and there is no direct verification that these factors are appropriate to handle the dynamic loading of earthquake induced ground motions. In this paper we investigate the interaction effects between piles under static and seismic loading using the computer program VERSAT-P3D, which uses an equivalent linear constitutive model for the soil. The analytical procedure is calibrated using data from a static field load test on a single pile. Several pile groups, 2 × 2, 3 × 3, 4 × 4, 5 × 5, 8 × 8, 10 × 10, 10 × 2 and 15 × 2 were analysed for the study. Each group was subjected to static pushover and earthquake loading and the distribution of static and dynamic shear forces at various lateral displacements were evaluated. The study shows that the distribution of load within a pile group under dynamic loading varies significantly from the distribution under static loading and is strongly load intensity dependent. Current practice assumes that the distributions are similar.
KeywordsSoil–pile interaction Pile groups Continuum modelling of pile groups Distribution of load in pile groups under static and dynamic loading
The authors would like to acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC) through a Strategic Grant entitled “Soil-Structure Interaction in Performance Based Design of Bridges”.
- Brown DA, Reese LC (1985) Behavior of a large-scale pile group subjected to cyclic lateral loading. Report to the Minerals Management Services, US Dept. of Interior, Reston, VA. Dept. of Research, FHWA, Washington DC and US Army Engineer Waterways Experiment Station, VicksburgGoogle Scholar
- Finn WDL, Dowling J (2015) Modelling the effects of pile diameter. Can Geotech J (in press)Google Scholar
- Finn WDL, Dowling J, Taiebat M, Wu G (2014) Distribution of seismic loads in large pile groups. In: Proceedings of the 14th international conference of the international association for computer methods and advances in geomechanics (14IACMAG), KyotoGoogle Scholar
- Finn WDL, Wu G (2013) Dynamic analyses of an earthfill dam on over-consolidated silt with cyclic strain softening. Keynote Lecture, 7th international conference on case histories in geotechnical engineering, April 29–May 4, ChicagoGoogle Scholar
- Kaynia AM (1982) Dynamic stiffness and seismic response of pile groups. PhD Dissertation, Massachusetts Institute of TechnologyGoogle Scholar
- Kaynia AM, Kausel E (1982) Dynamic behaviour of pile groups. In: Proceedings of the 2nd international conference on numerical methods in offshore piling, AustinGoogle Scholar
- Morrison C, Reese LC (1986) A lateral-load test of full-scale pile group in sand. GR86-1, FHWA, WashingtonGoogle Scholar
- Walsh JM (2005) Full-scale lateral load test of a 3 × 5 pile group in sand. M.Sc. Thesis, Department of Civil and Environmental Engineering, Brigham Young University, UTGoogle Scholar
- Wu G (2006) VERSAT-P3D: a computer program for dynamic 3-dimensional finite element analysis of single piles and pile groups. Wutec Geotechnical International, Vancouver. http://www.wutecgeo.com/versat-p3d.aspx. Accessed 12 Aug 2015