Abstract: A three dimensional nonlinear finite element model of pile group foundation of a high-speed railway bridge was built. Combined with the corresponding data obtained from field tests, the rules of pile axial force, pile side friction force, soil additional stress, pore water pressure distribution, excess pore water pressure dissipation and settlement of pile group foundation were analyzed. The calculation results show that the axial forces of corner piles are larger than the side piles which are larger than the center piles; and the axial forces of corner piles and side piles reduce greatly along the pile body; and the axial forces of center piles decrease slowly. Moreover, the regular pattern of pile side friction is that the pile side friction measurement of corner piles are larger than the side piles which are larger than the center piles generally; and the amount of relative displacement between pile and soil is bigger on the upper and less on the lower. That is to say, the amount of relative displacement between pile and soil on the upper of pile is larger than on the middle and lower of pile. Furthermore, the soil additional stress and excess pore water pressure generated by external loads mainly concentrate in soil under the pile cap within a certain range; and their attenuation gradients decrease along the depth gradually. With the increasing of the consolidation time, the settlement of pile group foundation arrives to be stabilized.

Key words: pile foundation, soft soil stratum, nonlinear finite elements, pile-soil interaction