A Novel Strength Reduction Method for a Slope Stability Assessment Based on a Finite Element Method

Ensuring the stability of slopes is critical to the safe operation of geotechnical engineering. Evaluating slope stability to minimize geologic risks induced by destabilization is significant in reducing casualties and property damage. A conventional, single-coefficient strength reduction method is widely applied in slope stability analyses, but this method ignores the attenuation degree of different parameters in the slope destabilization. A new double-strength reduction method considering different contributions of the mechanics’ parameters is proposed in this study for evaluating the stability of nonhomogeneous slope. First, the role of each mechanic’s parameters in the slope destabilization was investigated theoretically and numerically using ABAQUS software 2022. The results indicate that the effect of elasticity (E), Poisson’s ratio (v), and soil gravity (γ) on the evolution of factor of safety (FOS) are insignificant and can be neglected compared with cohesive force (c), and angle of internal friction (φ). Next, an improved method was constructed to correlate the FOS with cohesive force (c) and the angle of internal friction (φ). Then, a numerical method was constructed based on the computation of the mathematical–mechanical relationship between FOS and the mechanical parameters, and the stability of slope is estimation based on the Mohr–Coulomb yield criterion. Finally, the double-strength reduction coefficient method proposed in this study, the limit equilibrium method, and the traditional finite element strength reduction coefficient method were applied to nonhomogeneous slopes and slopes containing a soft underlying layer for comparison, and the difference between them was within the range of ±5%. The results indicate that both the limit equilibrium method and the traditional finite element strength reduction method tend to overestimate the FOS of intricate slopes compared with the evaluated method proposed in this study. This parallel comparison serves to validate the accuracy of the double-strength reduction method proposed in the present study. Further, based on the proposed method, the relationship between slope stability and slope displacement is established, which provides a theoretical basis for the safety assessment of slope engineering.