Numerical simulation of layered anti-inclined mining slopes based on different free face characteristics

A large number of geological disasters such as collapse, landslide and debris flow occur in Southwest China, and coal mining is replacing natural forces as the main factor leading to disasters. The most significant external feature of mining slopes in the mountainous areas of Southwest China is that the terrain is high and steep. In this paper, the collapse and landslide hazards of anti-inclined mining slopes in southwest mountainous areas are counted, and the deformation trend, mechanical behaviour, fracture evolution process and deformation and failure mechanism of mining slopes under different free face characteristics are simulated by PFC^2D software. The results show that the stability of layered anti-inclined mining slope is high in the natural state. Only a large-area goaf will affect it. The horizontal displacement always lags behind the vertical displacement, indicating that the slope first produces settlement deformation and then shear failure. With the increase in the free face angle, the horizontal displacement at the top of the slope decreases gradually, and the horizontal and vertical displacements at the slope increase gradually. The value of the horizontal or vertical contact force near the slope toe is the largest. When the angle of the free surface is greater than 60°, the toe of the slope has tensile failure. With the increase in the height of the free face, the displacement generated by the slope gradually increases, the vertical contact force also increases. When the height increases to 250 m, the stability of the slope becomes higher. According to the fracture evolution process of the slope, the deformation and failure process of the slope is divided into three stages: caving and subsidence deformation stage—tensile crack deformation stage—creep deformation stage. The deformation and failure mechanism of the slope is creep tension cracking.