Multi-Parameter Stability Evaluation of Landslide Progressive Failure Based on Improved Slice Method and Shear Stress Model

To reveal the full-process characteristics of landslide stability with deformation evolution, this paper proposes a novel progressive failure stability analysis method based on the improved slice method. By analyzing the force distribution characteristics of thrust-type and traction-type landslides along the sliding surface, the dynamic evolution laws of the unstable zone, critical state zone, and stable zone on the sliding surface are clarified. Based on the stress–strain discontinuity of the sliding surface, parameters such as failure rate, failure area ratio, and friction resistance variation coefficient are introduced to construct a point–surface–body multi-dimensional stability evaluation index system, including Comprehensive Shear Resistance Method (CSRM), Comprehensive Displacement Method (CDM), Surplus Displacement Method (SDM), and Main Thrust–Main Tension Method (MTM). A new unbalanced thrust method is derived to realize the quantitative simulation of the whole progressive failure process of landslides. The Kaziwan large bedrock landslide is taken as an example for verification. The results show that the critical state slice (slice No. 29) determined by the new method is completely consistent with the investigation results; the calculated displacements are in good agreement with the measured values of multiple inclinometers; the four stability coefficients show regular attenuation with the forward movement of critical slices, which can effectively describe the catastrophe process of landslides from local initiation to overall penetration. This method provides reliable support for dynamic stability evaluation and catastrophe mechanism research of landslides.