A loose slope structure and multiple free faces in a step-like landform are important engineering geological factors that cause multistage landslides. Tensile cracks that develop inside the slopes and the free faces created by excavation will have an impact on determining the location of potential multistage sliding surfaces. However, it is difficult to accurately locate sliding surfaces with tensile cracks in multistage landslide stability analysis. To solve this problem, a new search method is proposed for multistage sliding surfaces: the discontinuous dynamic strength reduction method (DDSRM). A slope will exhibit discontinuous failure when tensile cracks form. Therefore, the DDSRM simultaneously considers the shear and tensile failure modes. In the DDSRM, the tensile cracks on the first sliding surface are set as a discontinuous surface to stop the development of these cracks. The DDSRM is applied to a multistage landslide caused by excavation on a slope located in Southwest China. The results show that the plastic zone obtained with the DDSRM is small and that all of the potential sliding surfaces can be identified by setting the tensile crack as a discontinuous surface. Thus, the DDSRM provides a new way to search for multistage sliding surfaces.

阶梯状地形中的松散斜坡结构和多个自由面是引起多阶段滑坡的重要工程地质因素。斜坡内部产生的拉伸裂缝和开挖产生的自由面将对确定潜在的多级滑动面的位置产生影响。但是，在多阶段滑坡稳定性分析中，很难精确地定位带有拉伸裂纹的滑动面。为了解决这个问题，提出了一种新的多级滑动面搜索方法：不连续动态强度折减法（DDSRM）。当形成拉伸裂纹时，斜坡将表现出不连续的破坏。因此，DDSRM同时考虑了剪切破坏模式和拉伸破坏模式。在DDSRM中，将第一滑动表面上的拉伸裂纹设置为不连续表面，以阻止这些裂纹的发展。DDSRM适用于西南地区某边坡开挖引起的多级滑坡。结果表明，用DDSRM获得的塑性区很小，并且可以通过将拉伸裂纹设置为不连续表面来识别所有潜在的滑动表面。因此，DDSRM提供了一种搜索多级滑动面的新方法。