Abstract: The reinforcing and restraining effect of pile groups and the soil deformation under the pile tips are the key problems in settlement calculation of pile groups. However, the research on pile groups settlement is insufficient and needs to be continued. The reinforcing and restraining effect of pile groups was analyzed using the shear displacement method. The relations of settlement and axial force between bottom and top of each pile in layered soils were deduced by the load transfer method, respectively. Based on virtual soil-pile model, the calculation formula of virtual soil-pile length was provided. The relations of settlement and axial force between top and bottom of each virtual soil-pile in layered soils were obtained. Flexibility coefficient matrix was ascertained by the boundary conditions and the balance equations of pile section and virtual soil-pile section. Pile groups settlement was obtained based on different pile cap types. Lastly, case study indicated that settlement predicted by the present method agrees well with those measured from real test of engineering cases. The proposed method has high accuracy. The research played a complementary and promoting role on the development of settlement theory of pile groups.

Key words: pile groups settlement, virtual soil-pile model, reinforcing and restraining effect, layered soils, flexibility coefficient