Response of a group of piles to liquefaction-induced lateral spreading by large scale shake table testing

Abstract

Liquefaction-induced lateral spreading has imposed severe damages to many important structures supported on pile foundations during past earthquakes. As a result, evaluation of pile response to lateral spreading is an important step towards safe and resistant design of pile foundations against this destructive phenomenon. Current paper aims to study the response of a group of piles subjected to liquefaction-induced lateral spreading using a large scale 1-g shake table test. General test results including time-histories of accelerations, pore water pressures, displacements and bending moments are presented and discussed in this paper. In addition, distribution of lateral soil pressure on piles and displacement patterns around the piles are investigated in detail examining two main concepts affecting the lateral soil pressures on a group of piles, namely shadow and neighboring effects. On the basis of the test results, a simple numerical method is implemented for predicting the behavior of single piles under lateral spreading. The results indicate that lateral soil pressures exerted from laterally spreading ground vary in individual piles of a group both in transverse and longitudinal directions depending on the pile position within the group. It was found that the behavior of a group of piles (without pile cap) in an infinite mild slope far from a free face is different from those located behind a quay wall or close to a free face which were reported by other investigators.