ABSTRACT

Centrifuge model tests have been conducted on pile groups in loose sand to investigate their response to lateral loads. The behaviour of two different model pile groups and one single pile in loose sand were investigated in a series of centrifuge model tests. The model pile groups were installed and then horizontal load was applied using a horizontal actuator at 100g. Two of the piles in each of the pile groups as well as the single pile were strain gauged to measure the bending moment distribution. Initial investigation focussed on the lateral displacements and the rotations of the pile groups and the bending moment. These showed how the pile group shared the load between the front and back row. Manipulation of the bending moment data allowed p-y curves to be obtained for different depths for each of the piles. These p-y curves are presented for the two pile group spacings and are compared to the results from the single pile to deduce the group interaction effects. The results show that although the group p-y curves were softer, the pile group response was stiffer than the single pile response due to complex pile group interaction effects.

INTRODUCTION

Vertical piles are often subjected to lateral loadings that arise from earthquakes, high winds, wave action as well as earth pressures. Hence, the lateral load components in design should be considered as they can cause serviceability problems due to excessive lateral displacements or bending of the piles. There has been a rapid development in the last three decades in numerical and analytical methods ranging from elastic boundary element, finite element to non-linear subgrade reaction methods and these have been backed up by experimental work.

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