中文摘要：

Understanding three-dimensional （3D） slope deformation and failure mechanism and correspondingstability analyses are crucially important issues in geotechnical engineering. In this paper, the mechanismsof progressive failure with thrust-type and pull-type landslides are described in detail. It isconsidered that the post-failure stress state and the pre-peak stress state may occur at different regionsof a landslide body with deformation development, and a critical stress state element （or the soil sliceblock） exists between the post-failure stress state and the pre-peak stress state regions. In this regard,two sorts of failure modes are suggested for the thrust-type and three sorts for pull-type landslides,based on the characteristics of shear stress and strain （or tensile stress and strain）. Accordingly, a newjoint constitutive model （JCM） is proposed based on the current stability analytical theories, and it can beused to describe the mechanical behaviors of geo-materials with softening properties. Five methods, i.e.CSRM （comprehensive sliding resistance method）, MTM （main thrust method）, CDM （comprehensivedisplacement method）, SDM （surplus displacement method）, and MPM （main pull method）, for slopestability calculation are proposed. The S-shaped curve of monitored displacement vs. time is presentedfor different points on the sliding surface during progressive failure process of landslide, and the relationshipbetween the displacement of different points on the sliding surface and height of landslide bodyis regarded as the parabolic curve. The comparisons between the predicted and observed loadedisplacementand displacementetime relations of the points on the sliding surface are conducted. Theclassification of stable/unstable displacementetime curves is proposed. The definition of the main slidingdirection of a landslide is also suggested in such a way that the failure body of landslide （simplified as＂collapse body＂） is only involved in the main sliding direction, and th

英文摘要：

Understanding three-dimensional (3D) slope deformation and failure mechanism and corresponding stability analyses are crucially important issues in geotechnical engineering. In this paper, the mecha-nisms of progressive failure with thrust-type and pull-type landslides are described in detail. It is considered that the post-failure stress state and the pre-peak stress state may occur at different regions of a landslide body with deformation development, and a critical stress state element (or the soil slice block) exists between the post-failure stress state and the pre-peak stress state regions. In this regard, two sorts of failure modes are suggested for the thrust-type and three sorts for pull-type landslides, based on the characteristics of shear stress and strain (or tensile stress and strain). Accordingly, a new joint constitutive model (JCM) is proposed based on the current stability analytical theories, and it can be used to describe the mechanical behaviors of geo-materials with softening properties. Five methods, i.e. CSRM (comprehensive sliding resistance method), MTM (main thrust method), CDM (comprehensive displacement method), SDM (surplus displacement method), and MPM (main pull method), for slope stability calculation are proposed. The S-shaped curve of monitored displacement vs. time is presented for different points on the sliding surface during progressive failure process of landslide, and the rela-tionship between the displacement of different points on the sliding surface and height of landslide body is regarded as the parabolic curve. The comparisons between the predicted and observed loadedis-placement and displacementetime relations of the points on the sliding surface are conducted. The classification of stable/unstable displacementetime curves is proposed. The definition of the main sliding direction of a landslide is also suggested in such a way that the failure body of landslide (simplified as“collapse body”) is only involved in the main sliding direction, and the strike and the di