Numerical Analysis of Dynamic Response and Influence Factors on PCC Pile Composite Foundation of High Speed Railway

In this paper, a reasonable train dynamic loading form is determined, and a finite element model of PCC pile composite foundation for high speed railway is established using ABAQUS software. The dynamic response is simulated on subgrade and pile-soil composite foundation under different train speeds. The dynamic stress and acceleration changes of composite foundation are analyzed by changing the modulus of the roadbed surface layer and cushion. The results show that the changes of train speed, stiffness of roadbed and cushion layer react differently according to the laws of distribution and dispersion for dynamic stress, acceleration response of subgrade and pile-soil composite foundation. The dynamic stress and acceleration in roadbed surface increase with the increase of train speed. The changes in stiffness of roadbed have little effect on dynamic stress of the lower pile area, while the cushion is significantly influenced, by as much as 90%. The cushion has the effect on adjusting pile and soil dynamic stress ratio which may result in up to a 50% change in difference. A dynamic stress arch effect appears in the cushion under the dynamic interaction of the pile and cushion layer, which is similar to the static soil pressure arch effect.