School of Transportation，Southeast University
National Natural Science Foundation of China (No. 52078129)
Strength composite pile is a new type of pile formed by inserting a precast concrete pipe pile into cement-improved soil. A series of shaking table model tests and finite difference analysis using FLAC3D were carried out to research the seismic response of strength composite pile in a liquefiable ground. The accuracy and reliability of the numerical model were verified by the model test results, and the effects of the diameter, length and modulus of soil-cement columns, relative density of sand, and seismic intensity on the seismic response of sand-composite pile-superstructure were clarified. In addition, the anti-liquefaction performance of liquefiable ground and the bending failure of composite piles were evaluated. Results shows that increasing the diameter and length of soil-cement column can effectively improve the seismic performance of composite pile. Increasing the shear modulus of soil-cement column to improve the seismic performance of composite piles is limited. A large moment response may occur in the pile at the interface of cement-improved soil and liquefiable sand, so necessary seismic structural measures should be considered at the part. Based on the evaluation results, the key points of seismic design for composite piles in liquefiable soil were proposed.