Nonlinear Numerical Analysis of the Performance of Disconnected Piled Raft Foundation

Disconnected piled raft (DPR) is a new foundation system in which piles are separated from the raft by a granular cushion layer. This cushion serves to adjust the load sharing between the raft and the piles. This research investigates the behavior of DPR foundations resting on loose sand under uniform vertical loads. Three-dimensional finite element analyses are conducted to simulate the complex interactions within the DPR system, considering the soil nonlinearity. The primary objective of these numerical analyses is to compare the performance of DPR foundations with piled raft (PR) foundations in terms of load transfer mechanism, load-settlement behavior, and load-sharing ratios. Furthermore, the structural response of the piles in both PR and DPR foundations is examined by comparing the axial loads, bending moments, and shear forces induced in the piles. The results indicate that the PR foundation is more effective than the DPR foundation in improving raft settlement. However, the difference in settlement efficiency between the two systems is relatively small, and the DPR system proves to be quite efficient in reducing settlement. In addition, it is found that in DPR system, the soil between piles carries the major part of the applied load, especially in the initial loading stage, and the load sharing of piles is much lower than that for PR system. Moreover, A significant reduction in axial loads, bending moments, and shear forces in the piles is observed in DPR compared to the PR.