ABSTRACT:

There are relatively few reported field studies on the behaviour of laterally loaded rock socketed piles. This paper presents case studies of piles socketed in granite and sedimentary rocks that have been laterally load tested to failure. The load-deflection response, and deflection and bending moment profiles along the pile are presented. A back analysis using a one-dimensional finite element computer program is conducted to evaluate the pile performance. In addition, the effect of top soil stratum on the pile performance is investigated.

INTRODUCTION

There have been considerable work reported on the behaviour of axially loaded rock socketed piles, see for example Leung (1996). On the contrary, there are relatively few case histories reported on the performance of laterally loaded socketed piles. In the course of several major construction projects in Singapore, a good number of cast-in-situ concrete bored piles were laterally load tested to failure. These piles were installed in silty clay/clayey silt/sand of various depths and subsequently socketed in granite or sedimentary rock of different socket lengths. The pile performance was evaluated using a one-dimensional finite element computer program. The Subgrade Reaction method was employed to establish the correlation between the subgrade modulus and the soil/rock parameters by back analysing the linear portion of lateral load-deflection responses of the test piles. An elasto-plastic model is then employed to predict the non-linear load-deflection behaviour of the piles. The performance of the laterally loaded socketed piles and the results of the back analysis are presented in this paper.

FINITE ELEMENT ANALYSIS

A one-dimensional finite-element analysis (Leung and Chow, 1987) is employed to predict the deflection of a laterally loaded pile. A computer program is written to incorporate the analysis whereby the pile is discretized into elements to take into account the different soil strata.

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