<p>The effect of groundwater table (GWT) variation on the behavior of piled raft (PR) foundation is complex, as it involves interactions between the raft, piles, and soil within the fully saturated region, an overlying capillary saturated region, and an unsaturated region up to the ground surface. There is limited research on the influence of the transient flow caused by GWT fluctuation on the PR response. In the study, incorporating the principles of unsaturated soil mechanics, three-dimensional numerical analyses have been performed to investigate the large PR behavior in clayey soil with different pile configurations and loading intensities, and subjected to a continuous GWT drawdown. Results show that the PR exhibits higher suction stress and a lower degree of saturation than the unpiled raft in the unsaturated zone. For a lower loading intensity, both average and sagging differential settlements increase with GWT drawdown, while for a higher loading intensity the average settlement increases and sagging differential settlement decreases with the drawdown. For a continuous drawdown, the serviceability criteria is satisfied only with a greater total pile length. For the higher loading intensity, due to the drawdown, the load-sharing ratio increases only for higher pile number, closer pile spacing, or shorter-length piles.</p>