Effects of vertical load of superstructure on piled raft foundation in sand subjected to static horizontal and moment load

Abstract

Piled raft foundation has been widely recognized as a rational and economical foundation system with the combined effects of raft and piles. However, the behavior of piled raft foundation subjected to horizontal and moment load has not been well clarified due to complex interaction of raft, ground and piles. A series of centrifuge model tests was conducted on the piled raft model and its components of pile group and raft models. In this paper, a focus was particularly placed on the influence of the vertical load of the foundation on the behavior of laterally loaded piled raft foundation. From the centrifuge model tests, it was found that the raft base pressure in the piled raft foundation enhances the horizontal and moment resistance carried by piles. In addition to the increase of pile resistance, mobilization of raft resistance contributes to higher horizontal and moment resistance of the piled raft foundation compared with the pile group foundation. The increase of vertical load of the foundation results in relatively larger settlement for both piled raft and pile group foundation. However, the increase of settlement associated with the vertical load of the foundation can be restrained for the piled raft than the pile group foundation. This relatively large settlement of the foundation secures the contact condition between the raft and the ground. Therefore, above mentioned positive effects of the raft part can be more significantly expected for the piled raft with relatively larger vertical load of superstructure.