Abstract: The pile foundation is widely used in the engineering construction because of its high axial capacity and the small settlement. The mechanical properties of the pile-soil interface are the key factors affecting the axial capacity and the settlement deformation of the pile foundation. In engineering practice, the unsaturated soil is widely distributed, and the settlement prediction and the axial capacity prediction of the pile foundation are often far from the theory. The theoretical research on the interaction between the unsaturated soil and the pile is far behind the engineering practice requirements. This paper summarizes the research on the mechanical properties and failure mechanism of the pilesoil interface, the pattern of the pile-soil load transfer and the consolidation theory of the soil around the pile foundation, to provide a reference for the relevant research.

Key words: Pile Foundation engineering, Unsaturated Soils, Pile-Soil Interaction, Load Transfer, Composite Foundation Consolidation