Study on deformation mechanism and shape optimization of multi-weak interlayer slope in open-pit mine

Aiming at the slope design problem of the open pit mine of dip final beded slope with weak layer,and combined with the actual situation of field engineering,through the analysis of engineering geological characteristics such as geological structure,lithology of rock strata and occurrence of weak interbeds,the deformation and failure characteristics,landslide mode and the influence of different weak beds on slope stability are studied by using rigid limit equilibrium theory and numerical simulation. The final shape of the boundary slope is optimized by using the sectional optimization method. It ensures the safety and efficiency of coal resources recovery and maximizes the recovery of coal resources in the process of end-to-end mining,and provides a reference for landslide prevention and control of similar slope projects. The results show that the upper rock mass of open pit slope with multi-weak beds and fault structure has many weak beds and serious weathering and low strength. With the increase of pit depth,the restraint effect of rock mass at the lower fault zone on the upper rock mass decreases. The potential landslide mode of multi-weak beds along inclined slope at the end of open pit coal mine is pulled downwards,which leads to bedding sliding along weak beds. Weak mudstone is the dominant layer of landslide,and the relative position relationship between weak mudstone beds and fault fracture zone is the dominant factor of landslide. When the slope angle of the section above Fault F5 is 12°and that of the section below Fault F5 is 18°,the slope angle of the section below Fault F5 is 18°，The overall slope angle is 14°,and the slope can be in a stable state.