Shaking Table Test on Liquefaction of Sandy Soil Site and Sensitivity Analysis of Liquefaction Influencing Factors

Earthquake-induced soil liquefaction poses a severe threat to the structural safety of underground infrastructure. This paper presents a shaking table model test conducted on sand sites, where two site models—namely, uniform saturated sand and layered dry–saturated sand—are designed to systematically analyze the influences of seismic wave amplitude, seismic wave frequency, and structure burial depth on the development of pore water pressure. The research findings indicate the following: (1) As the input peak ground acceleration (PGA) increases, the output surface peak ground acceleration rises, while the acceleration amplification factor decreases. Under high-intensity earthquakes, sand boiling and water gushing are observed in the uniform saturated sand site, and the overlying unsaturated layer can effectively inhibit the liquefaction development of the underlying saturated sand layer. (2) When the predominant frequency of the input seismic wave is close to the natural vibration frequency of the test site, the surface acceleration response is significantly enhanced, while the resonance effect of low-frequency seismic components is relatively weak. (3) The pore pressure ratio is higher in shallow soil layers, indicating that shallow strata are more prone to liquefaction. Both the pore pressure accumulation rate and the peak pore pressure ratio under uniform saturated sand conditions are higher than those measured in the layered dry–saturated sand site. (4) The sensitivity ranking of the three influencing factors is input PGA > burial depth > seismic wave frequency, where the input PGA is the dominant influencing factor, and the effect of the seismic wave frequency is not statistically significant. The conclusions of this study can provide a reference for seismic response assessment and anti-liquefaction design of shallow-buried structures in liquefiable sites.