Effect of pile length on the behavior of pile raft foundation

This study investigates the influence of pile length on settlement and straining actions of a piled raft foundation and load-sharing mechanism between piles and the raft. Finite element analysis using PLAXIS 3D and SAP 2000 was conducted to study key parameters such as settlement, bending moment, shear force, and load distribution. It can be observed from the results that with an increase in pile length from 8m to 12m, the settlement reduces by 42%,, while further extension to 14m and 16m results in diminishing returns with reductions of 12.7% and 9.97%, respectively. Regarding bending moment, an increase in pile length from 8m to 12m decreases it by 4.7%, while extending from 12m to 16m results in an additional 5% reduction. Similarly, the raft shear force decreases by 5.26% when pile length increases from 8m to 12m, with marginal reductions beyond that. The load-sharing analysis reveals that at 8m pile length, the raft carries 38% of the total load, which reduces to 22% at 12m and 14m, and 19% at 16m, demonstrating the increasing reliance on piles for load- bearing. The study highlights the optimal pile length for maximizing settlement reduction and efficient load distribution, offering practical guidance for foundation design improvements.