The piled-raft foundation is a new design concept as one of the effective methods of foundation to reduce settlements of structures. However, the general design method of piled-raft foundation system usually assumes that the piles only support all the external loads, which exclude the bearing capacity of raft itself.
In this study, numeral analysis and experimental model test are performed to evaluate the raft capacity to the external load on the sand. Additionally, the part of sandy ground under the raft replaced with gravel mat to enforce piled-raft foundation system to enforce the bearing capacity. Then, the parametic studies of enforced ground are carried out for the displacement and bearing capacity of the piled-raft foundation system.
As the results of this research, 1)The load bearing ratio of raft is increased to the applied external load in the enhanced gravel mat ground. 2)The piled-raft foundation enforced by gravel mat decreased settlements to the applied external loads. 3)The gravel mat under the raft reduced the distribution load of piles.