Simulation and Analysis on Ground Vibrations of Pile-Net Composite Subgrade Under High-Speed Train Loadings

The pile-net composite subgrade is a widely adopted construction for high-speed railway in China. This study employs a 3D finite element method (FEM) model to investigate the influences of soil type and pile-net composite subgrade design parameters on ground vibrations induced by high-speed trains moving on such composite foundations. The model comprise the track, embankment, geogrid, pile caps and piles. The results reveal that the ground vibrations exhibit a decreasing trend with the increasing distance from the track center under different soil types, and the attenuation rate of ground vibrations in softer soil is higher than that in the stiffer soil. The types of foundation soils have a considerable influences on the vibration attenuation, especially for the far track zone. The peak ground vibration acceleration decreases with increasing pile diameter and the decreasing pile spacing. Moreover, the pile diameter exters a greater impact on ground vibrations than the pile spacing, especially for the near track zone.