Influence Analysis of Subgrade Height and Foundation Modulus on Subgrade Dynamic Characteristics under High-Speed Train Load

Subgrade dynamic displacement and stress are strictly restricted in high-speed railway line to guarantee train operation. On basis of the in-situ test study of Beijing-Shanghai ballastless railway line, a numerical model is conducted to investigate dynamic response characteristics under high-speed train load by considering three related factors: subgrade height, foundation modulus, and reinforcement form. Numerical results indicate that according to subgrade dynamic response, the critical subgrade height is 3.0m, the critical foundation modulus is 40MPa, and pile-net and pile-raft composite foundation can satisfy subgrade vertical dynamic displacement threshold (0.200mm) of high-speedrailway line when well-designed.