Study of dynamic characteristics and damage mechanism of pile–net composite roadbeds in high-speed railways under seismic action

Shaking-table model experiments were conducted to study the dynamic response and damage mechanisms of pile–network composite high-speed railway foundations under seismic action. By inputting seismic waves of various types and acceleration amplitudes, the surface damage phenomena, acceleration response, and displacement response of the roadbed during vibration were analyzed. The time frequency information and energy distribution were examined using Hilbert marginal spectrum theory. Additionally, the damage mechanisms of the model were explored through transfer function analysis. The results indicated that the soil surface deformation measured using particle image velocimetry closely matched the observed macroscopic phenomena. The Peak Ground Acceleration amplification coefficients exhibited clear delamination before the structure showed signs of damage, indicating a significant energy-absorbing effect of the bedding. Spectral analysis revealed that as the vibration intensity increased, the nonlinear characteristics and damage effects of the model became more pronounced, and its ability to dissipate energy strengthened. Energy became more concentrated in the left half of the top section of the model. Moreover, as the vibration intensity increased, the self-oscillation frequency of the roadbed decreased, the stiffness diminished, the damping ratio increased, and the seismic energy dissipation improved.