Study on High and Steep Slope Stability and Slope Angle Optimization of Open-Pit Based on Limit Equilibrium and Numerical Simulation

The stability of open-pit slope is related to mine safety, especially for high and steep slope. In order to obtain the design slope stability and slope angle optimization of K mine open-pit in Myanmar, limit equilibrium analysis method and three-dimensional numerical simulation are used to carry out the study on the slope stability. The results show that: (1) The safety factor of the designed slope is larger than the allowable safety factor by using the limit equilibrium analysis, which belongs to the stable slope. Some areas can be optimized for design. (2) Through three-dimensional numerical analysis, the design slope and the optimized slope are both stable. The area with large deformation of the optimized slope is mainly concentrated in the area of 562 m level moderately weathered pyroclastic rock in area A and 560 m level moderately weathered rock in area B. The calculation results of three-dimensional numerical simulation are basically consistent with the results of the limit equilibrium analysis. (3) Compared with the designed slope, the potential sliding surface position of the optimized slope is lower. The safety factor is smaller, but larger than the allowable safety factor. The shape of the sliding surface of the whole slope is nearly circular arc. The sliding mode of the slope is circular arc sliding. (4) The reasonable slope angle of different engineering geological divisions of the open-pit slope of K mine is determined. The overall slope angle of area A is ≤ 46°. The overall slope angle of area B is ≤ 44°. The overall slope angle of area C is ≤ 45°. The overall slope angle of area D is ≤ 50°. The research results can provide reference for mine safety production.