Three Dimensional Nonlinear Seismic Behaviour of 3 × 3 Pile Groups in Liquefiable Soil

Abstract

Dynamic behaviour of soil-pile interaction is a complex problem. The complexity enhances when the soil medium is liquefiable. Studies on dynamic behaviour of pile groups are limited considering the fact that the interaction effect gets complicated when pile groups is embedded in liquefying soil. The dynamic behaviour of 3 × 3 pile groups with three different spacing among the piles are investigated considering plasticity and liquefaction of the soil medium. A three-dimensional finite element program has been developed in MATLAB for the study. Work hardening plastic cap model has been considered for the soil medium and the pore pressure generation for liquefaction was incorporated by a two-parameter volume change model already established in the literature. The three-dimensional soil-pile model developed for the study has been validated with the established literature. Non-dimensional dynamic stiffness and the seismic response of the pile groups have been computed considering the effects of soil plasticity and the liquefaction of the soil medium. The study was performed for a range of frequency of excitation. The study quantifies the effects of soil plasticity and liquefaction on the dynamic behaviour of pile groups for different frequency of excitation and hence underlines the importance of soil plasticity and liquefaction on the kinematic soil-pile interaction problems. © 2013 Indian Geotechnical Society.