An analytical solution for critical sliding surface of stepped rock slope: a case study of Xinjing coal mine landslide

A large and catastrophic landslide occurred at the Xinjing Coal Mine (XCM), China on February 22, 2023, resulting in 59 casualties. It was reported that one of the triggering factors of this landslide was that the actual engineering slope, which was excavated by reduced steps. This paper presents analytical approaches to investigate the effects of steps number and steps width on the stability of stepped rock slopes. The dip angle of sliding surface θ was used to characterize the critical sliding surface (CSS) of rock slopes, and analytical solution of θ was derived with limit equilibrium method (LEM). Discrete element method (DEM) was conducted to verify the accuracy of the proposed approach. The effects of the geomechanical and geometric parameters on XCM Landslide were investigated by parametric analysis. It was found that the driving factors of the XCM Landslide was the design slope steps numbers was reducing from 4 to 3, i.e., the slope was excavated with combined-step. Specifically, with the increase of the number and width of steps, the slope stability gradually improved. This study provides useful guidelines to location of CSS of open pit slopes and scientific design of open pit mine rock slopes with multi-steps.