Force distribution during progressive slope failure is an important element in slope stability analysis. In this study, five mechanical failure modes are proposed for thrust‐ and pull‐type slopes, respectively, and five field forms of thrust‐type slopes are described. The properties of progressive failure are evaluated quantitatively: the failure mode of slope obeys the geo‐material rule under the peak stress state, and the instability range is gradually developed. The critical stress state zone is in the process of dynamic change with the development of deformation. It appears that the driving sliding force is greater than the frictional resistance along the sliding surface. When rock or soil stabilizing stresses are at maximum, the vector sum of the driving sliding stress and stabilizing stress is equal to zero at the critical state. The frictional resistance is equal to the driving sliding force in the stable and less‐stable regions, and the normal pressure is wherever equal to the counterpressure. Rigid, flexible, and rigid‐flexible design theories are proposed for slope control. New terms are defined and used to evaluate the stability. The conventional local and surplus stability factors of slopes and their calculation are explained. The force distribution rule is analyzed during progressive failure, and the conventional stability factor definition is discussed. The geological settings and monitoring data of landslides are used to analyse changes in the critical stress state. An example is given to illustrate the failure process analysis. The results show that progressive failure can be well represented and the safety factor can be well described by the main thrust method (MTM), comprehensive displacement method (CDM), and surplus displacement method (SDM), which can be used to feasibly evaluate slope stability.

The existing stability analysis of Coulomb retaining walls is derived on the basis of four assumptions, and there is no clear description of the interaction mechanism among wedge-shaped bodies, retaining walls, and the two. This article proposes a new method for calculating the stability of Coulomb retaining walls. For soil wedges and retaining walls, numerical theoretical solutions for the stress distribution in soil wedges and retaining walls were obtained on the basis of stress balance differential equations, coordination equations, force boundary conditions, and macroscopic equilibrium. The boundary condition between the soil wedge and the retaining wall is that the resultant force and moment between the two are continuous. Assuming that the soil wedge and retaining wall satisfy the Duncan–Zhang model and the linear elastic Hooke constitutive model, respectively, the strain solutions of the soil wedge and retaining wall are obtained. Assuming that both the peak strength criteria for the soil wedges and the concrete retaining walls satisfy the Mohr–Coulomb criterion, the location of the first point of failure for the soil wedges and retaining walls is determined. Taking the garbage transfer station in Lvcongpo Town, Badong County, as an example, the analysis of the force and displacement of the retaining wall and years of operation show that the proposed method for calculating the stress and strain of the retaining wall and the new method for evaluating the stability of the retaining wall based on the point strength criterion are feasible.

An analytical method for determining the stresses and deformations of landfills contained by retaining walls is proposed in this paper. In the proposed method, the sliding resisting normal and tangential stresses of the retaining wall and the stress field of the sliding body are obtained considering the differential stress equilibrium equations, boundary conditions, and macroscopic forces and moments applied to the system, assuming continuous stresses at the interface between the sliding body and the retaining wall. The solutions to determine stresses and deformations of landfills contained by retaining walls are obtained using the Duncan-Chang and Hooke constitutive models. A case study of a landfill in the Hubei Province in China is used to validate the proposed method. The theoretical stress results for a slope with a retaining wall are compared with FEM results, and the proposed theoretical method is found appropriate for calculating the stress field of a slope with a retaining wall.

Slope failure generally starts from a single point, where a local failure surface forms, and then progresses to the overall failure. Based on this behavior, this paper proposes a multi‐criterion stability evaluation approach for describing progressive failure process of slope. The criteria for slope body failure (main thrust, surplus friction resistance, comprehensive displacement, and surplus displacement) are adopted to evaluate the stability during progressive failure process. The sliding surface boundary method (SBM), partial strength reduction method (PSRM), and free surface boundary conditions for slope stability numerical analysis are adopted, in which the gradual movement of the critical stress state of the sliding surface is simulated for selected boundary conditions, reproducing the entire process of gradual slope failure. The case study of the Dianzhan slope located in the Wufeng County in Hubei Province shows that the multi‐criterion stability evaluation approach adopting PSRM and SBM can better describe the evolution of various slope stability and failure characteristics. Comparing the stability coefficients calculated by traditional methods with the method proposed herein provides a novel theoretical basis of slope stability assessment, early instability warning, and slip‐resistant design.

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.