Seismic performance and damage characteristics of pile network composite-reinforced high-speed railway subgrade

Abstract

A series of large-scale shaking table tests was conducted on a pile network composite-reinforced high-speed railway subgrade. The displacement, peak acceleration amplification factor, dynamic soil pressure, and geogrid strain data were used to investigate the dynamic characteristics. The Hilbert–Huang transform spectrum, marginal spectrum, and damping ratios were used to study the seismic energy dissipation characteristics and damage evolution mechanisms of the reinforced subgrade. The results indicate that the graded loading of seismic waves induces a global settlement phenomenon within the subgrade, the displacement phenomenon of the slope is more evident, and the reinforcement effectively mitigates the amplification effect of the peak acceleration along the elevation. The peak and cumulative residual dynamic soil pressures were most significant near the bedding layer, and the upper and middle parts of the subgrade exhibited superior stabilization performance. The geogrid reduced the local vibration variability and enhanced the overall stability. The damage evolution in the middle part of the subgrade was relatively gentle, whereas the slope exhibited a multistage development trend. The internal damage of the subgrade grows slowly at 0.1–0.2 g, faster at 0.2–0.6 g, and rapidly at 0.6–1.0 g.