Numerical Simulation Study on the Mechanism of Loess Slope Landslide Formation under Rainfall Effects

In the Ili region of Xinjiang, there are a large number of loess slopes. Combined with the high rainfall in the Ili Valley, it often poses hazards to engineering construction. Under the influence of rainfall, the moisture content of the loess increases significantly, leading to sliding and failure at the contact surface between the loess and gravel layers. In order to comprehensively analyze the mechanism of loess surface slope landslide under the effect of rainfall, this study conducted field sampling of typical landslides in the area and performed laboratory direct shear tests and finite element numerical simulation studies. The results showed that: after the increase in moisture content, the cohesive strength of the loess increased to some extent, but the internal friction angle continued to decrease, resulting in a continuous reduction in shear strength. The contact surface between the loess and gravel layers was prone to sliding and failure. Under self-weight conditions, the maximum displacement was 3.7cm, while under rainfall conditions, the maximum displacement reached 56.7cm. This is because rainwater infiltration changes the contact form between the loess particles, reducing its shear strength, and the increase in moisture content makes the loess more prone to plastic deformation. After implementing anchor support measures, the maximum displacement of the slope under rainfall conditions decreased to 27.5cm, demonstrating a significant supportive effect. This study can provide reference for the prevention, early warning, and control of loess surface slope landslides in the Ili region.