Abstract: Internal crack in rock slope may grow under seismic loading, which would have an adverse effect on slope stability. By taking advantage of extended finite element method (XFEM), the development of cracks in a rock slope located in the southwest China under seismic loading is simulated. An analysis of the potential sliding surface is carried out according to the crack after extension, and the factors of safety are calculated with vector sum analysis method (VSAM) before, during and after earthquake. The result shows, under the loading of Wenchuan seismic waves, both crack LLT1 and crack LLT2 grow. The angle between growth-direction and the horizontal is nearly 45 degree, and the crack LLT1 grows to the slope surface. The factors of safety before and after earthquake are 1.75 and 1.05 respectively, and the minimum factor of safety during the earthquake is 1.01. This illustrates that the slope is stable before earthquake, but the anti-sliding force and the slope stability are both reduced because of the growth of crack under the seismic loading. Even if the slope is stable in the process of the earthquake, it may collapse subjected to other forces after earthquake.

Key words: earthquake, crack, slope stability