A parametric study of large piled raft foundations on clay soil

Abstract

In the present study, three-dimensional numerical analyses have been conducted to understand the behavior of large piled rafts on stiff clay. The effects of pile number, pile spacing, pile length and loading intensity have been examined. For the same soil, the raft thickness is varied such that the its stiffness changes from flexible to intermediate flexible and to rigid. The load-settlement behavior, load-sharing ratio, raft bending moment and pile axial load distribution are presented and discussed in detail. For a higher pile number, locating piles over a larger central raft area is necessary for the effective reduction of differential settlement. For the intermediate flexible raft, addition of piles covering the maximum raft area is not beneficial in decreasing the differential settlement or the raft bending moment. With the intermediate flexible raft, decreasing the pile length can prove to be advantageous in removing hogging differential settlement. Based on the loading intensity and serviceability limit considerations, the appropriate pile configuration can be determined from the results of the parametric study in the cyclical sequence of firstly the selection of pile number, secondly the adjustment of pile spacing, and finally the reduction of pile length.