Abstract: The analysis of slope stability under a nonlinear strength criterion presents significant challenges due to the coupling of slope failure modes, stress distribution on the slip surface, and soil strength parameters. In this study, these challenges are addressed by employing a stress-based calculation mode for the slip surface, as opposed to the assumption of inter-slice forces under the slice division. Additionally, the nonlinear Mohr-Coulomb (M-C) strength criterion is incorporated, and stress constraint conditions at both ends of the slip surface are introduced. This, along with the global mechanical equilibrium conditions of the sliding body, establishes a limit equilibrium solution for slope stability with nonlinear failure characteristics using the stress-based calculation model for the slip surface. Furthermore, the slip surface is generalized to a curve represented by the polar diameter and polar angle under the rotating center point, creating a generalized generation model of the slip surface. For layered slopes, a rational connection mode for the inter-layer slip surfaces is proposed based on the most unfavorable shear direction under continuous stress. To integrate the limit equilibrium solution of slope stability under the stress-based calculation mode for the slip surface and the generalized generation of the slip surface, a joint iterative method for the polar diameter, stress, and strength of the slip surface is adopted. Through the comparison and analysis of several slope cases, the feasibility of the present method is verified, and the current work has the potential to contribute to a deeper understanding of slope failure mechanisms under the nonlinear strength criterion.

Key words: slope stability, limit equilibrium, nonlinear M-C strength criterion, coupling relationship of polar dimeter, stress and strength of slip surface, generalized model of slip surface, functions of stresses on slip surface