中文摘要：

在地震作用下岩质边坡内部裂隙可能开裂扩展，对边坡稳定造成不利影响。利用扩展有限元法模拟岩质边坡内部裂隙在地震作用下的开裂扩展，根据扩展后的裂隙分析边坡潜在滑面，采用矢量和法计算边坡在震前、地震过程及震后的安全系数。结果表明：在汶川地震波作用下LLTl与LLT2裂隙均开裂扩展，开裂方向与水平方向夹角近45°，其中LLTl裂隙项部开裂至边坡面。震前安全系数为1．75，地震过程中最小安全系数为1．01，震后安全系数为1．05。说明了即便是边坡在震前稳定性较好，但由于地震作用使得裂隙扩展贯通至边坡表面，导致滑体抗滑力降低，边坡震后稳定性显著降低。虽然地震过程中边坡并未失稳破坏，若在震后受到其他外部作用则可能失稳破坏，引发次牛灾害。

英文摘要：

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.