Initiation Mechanism of Shallow Loess Slope Sliding under Coupling Effect of Train Vibration and Rainfall

The large-scale construction and operation of the railway in Northwestern China has resulted in some geological disasters in recent times. Among them, the shallow sliding of the loess railway slope caused by the coupling effect of train vibration and rainfall has been a frequent occurrence, causing heavy losses of life and property. Accordingly, this is a major problem an needs an urgent solution. Therefore, this study used acceleration, pressure, moisture, and displacement monitoring equipment, among others, to conduct physical simulation experiments and theoretical analysis on the instability and sliding process of loess railway slopes under the coupling effect of train vibration and rainfall. The research results indicate that acceleration gradually decreases downward along the slope, and the pore water pressure and volumetric water content increase with the increase in rainfall infiltration. The slope displacement exhibits a phased increase after the initial slip. As vibration energy builds up, the slope bottom undergoes rapid structural damage and tensile shear coupled instability failure, followed by slip. Before sliding, both the crack density and fractal dimension of the slope have an active area, that is, a sliding slope area, which continues to expand upward under the cumulative effect of vibration energy. The failure process is divided into three stages according to the changes in macrodeformation, pressure, water content, displacement, and fractal dimension of the slope model: crack development stage, local liquefaction sliding stage, and slip propagation stage. This research elucidates the initiation mechanism of loess railway slope sliding under the coupling effect of train vibration and rainfall and provides a theoretical basis for predicting loess slope disasters under train vibration and providing adequate warning.