1 g Shake Table Study on Seismic Behaviour of Model Structure Supported by Pile Foundation in Liquefiable Soil

Abstract

Failure of pile foundation in liquefiable soil was evidenced in many past earthquakes. In fact, the complex interaction between soil, pile foundation and structure in liquefiable soil during seismic loading commonly known as seismic soil-pile foundation-structure interaction (SSPSI) is an important phenomenon which influences the dynamic behaviour of the whole structural system. Previously, SSPSI is generally disregarded in seismic design due to complexity in modelling and beneficial attributes of soil structure interaction as highlighted in previous codes. However, research indicates that argument still prevails with failure mechanism of pile foundation in liquefiable ground. In this context, present study is an attempt to assess the influence of dynamic interaction between soils, pile foundation and structure system during pre- and post-liquefaction stages by carrying out 1 g shake table experiments. Four physical models, consisting of 1 × 2 and 2 × 2, 3 × 3 and 4 × 4 pile groups supporting SDOF structure having fundamental period of 0.2 s and 2.0 s, respectively, are tested. Dynamic strain at pile head and pore water pressure is measured during pre- and post-liquefaction stages. Results indicate that pile foundation attracts higher forces and displacement during onset of liquefaction even though damping increases in the system. Finally, this study gives insight into the problem which may help in modifying existing seismic design guidelines for pile foundation supported structure in liquefiable soil.