Failure Mechanism Analysis of Loess Slope Under the Coupling Effect of Rainfall and Earthquake Using Shaking Table Test

Rainfall and earthquake are two main factors that trigger landslides. In practice, landslides would occur more easily under the coupling effect of them and present long sliding distance and large sliding scale characteristics, which brought huge losses and casualties to people. Shaking table test of a model loess slope was performed in the study. The wave of Minxian station in 2013 Minxian-Zhangxian Ms6.6 earthquake with intensities of 50 gal, and 100 to 800 gal (interval 100gal) were exerted on the slope successively. Then, the rainfall was applied after 800 gal by using artificial rainfall device and 1300 gal is applied at last. Based on Hilbert-Huang transform (HHT), we investigated the acceleration response of the slope in time-frequency-energy space. The change characteristics of Hilbert energy and predominate frequency under the single effect of earthquake and the coupling effect of rainfall and earthquake were analyzed based on marginal spectrum. According to the dynamic response results of the slope, failure mechanism and damage evolution law of the landslide under the coupling effect of rainfall and earthquake were clarified. The study shows that the coupling effect greatly decreased the stability of the slope and the final damage presents soil flow. The instantaneous energy and cumulative energy have a great dissipation under the coupling effect, which provide the kinetic energy to the soil flow.