Ground Vibration Reduction Analysis of Pile-Supported Subgrade for High-Speed Railway Using 2.5D FEM

A 2.5-dimensional finite element model (2.5D FEM) for predicting ground vibrations of the coupled track-pile-supported subgrade system was proposed. In the model, the equivalent pile wall approach was used to simulate the piles and surrounding soils. Reliability of the established model was verified with field measurements. Two types of high-speed railway subgrade, with or without piles, were chosen to be analyzed. The obtained results were compared to investigate the performance of subgrade improvement with piles in reducing ground vibration induced by high-speed train loads. Following that, the effects of pile parameters on ground vibration were studied. The study shows that subgrade improvement with piles significantly reduces the ground vibrations both for low-frequency and high-frequency components, and the vibration reduction performance gets better away from the track than close to it. Increasing pile diameter, increasing pile stiffness, or decreasing pile spacing could effectively reduce ground vibrations. However, there are critical values for these pile parameters in vibration reduction, beyond which the vibration reduction performance would no longer be improved.