Abstract: For the sake of calculating the exposed length of the slope with inclined weak-layers, and considering the occurrence characteristics of rock mass and the spatial geometry of the potential landslide, a simplified mechanical model was built for the three-dimensional landslide of the slope with inclined weak-layers. The mechanical conditions on the boundary of landslide body were analyzed. A method for the three-dimensional stability of slopes by calculating the exposed length of inclined weak-layers was obtained with the theory of limit equilibrium. The method was verified by CDEM in Baiyinhua 1st open pit mine. The results show that there is a negative correlation between the stability coefficient F_s and the exposed length L of the weak layer in Baiyinhua 1st open pit mine non-working slope, the critical exposed length is about 500 m and the allowable exposure length is about 300 m, and that the exposed length of weak layer determined by this method comforms with the simulation results.

Key words: slope stability, inclined weak-layer, three-dimensional limit equilibrium method, exposed length, continuum-based discrete element method(CDEM)