Optimization design method of 2D+3D slope shape for landslide prevention in open-pit coal mine

In order to improve the stability of the slope and prevent the occurrence of landslide disaster, this study took the east slope of the first mining area of Zhundong Open-pit Coal Mine as the engineering background, and used a combination of the two-dimensional limit equilibrium method and three-dimensional numerical simulation to optimize the shape of the east slope. By selecting a typical calculation profile based on the Bishop method and the residual thrust method in the two-dimensional rigid body limit equilibrium method, this research carried out the stability analysis of the profile slope, and preliminarily designed the slope shape of the profile position meeting the requirements of the safety reserve coefficient and stripping ratio. Based on the three-dimensional finite element strength reduction method, this paper investigated the reasonably change of the width of the transport plate to solve the problem of the slope shape that does not meet the requirements of safety reserve coefficient and stripping ratio, and established a three-dimensional numerical simulation model of various schemes. It also studied the influence of different tracking distances and slope angles on slope stability, calculated the three-dimensional stability of the slope under different spatial forms, then determined the optimal tracking distance and optimal slope angle, and further optimize the slope stability and stripping ratio. The results show that: when the width of the transport plate of the DBS3 section slope is 8 ​m, it does not meet the requirement of safety reserve coefficient 1.2; when the width of the transport plate is set to 24 ​m, it meets the requirement of a safety reserve coefficient of 1.2 and an economic stripping ratio of not more than 8.0 m3/t. The three-dimensional numerical simulation results concluded that the optimal tracking distance on the east side is 50 ​m, and the optimal slope angle is 35°. After the optimization design of a two-dimensional and three-dimensional slope shape, 2.456 million tons of coal resources were mined, creating a profit of about 21.1268 million yuan. It not only prevents landslide disasters, but also further improve the recovery rate of coal resources.