Abstract: In practical engineering, soil strength displays characteristics of spatial heterogeneity and anisotropy. Neglecting these characteristics complicates reliably evaluations of slope stability. Therefore, this study conducts an in-depth analysis of slope stability considering the spatial heterogeneity and anisotropy of soil strength. First, improvements were made to the existing spatial heterogeneity model and the original Casagrande anisotropy model to enhance their universality and practicality. Next, the spatial heterogeneity and anisotropy of soil strength were coupled and incorporated into the Mohr-Coulomb (M-C) strength criterion using an improved tensile-shear mode. Subsequently, within the framework of the limit equilibrium (LE) theory, a calculation mode of slip surface stress was employed to replace the conventional assumption mode of inter-slice force. This was achieved by constructing slip surface stress functions and introducing the concept of the local factor of safety for the slip surface, along with stress constraint conditions at the ends of the slip surface. This approach integrates the combined mechanisms of tension-shear and compression-shear, as well as the progressive failure modes of slopes. Finally, based on the overall mechanical equilibrium conditions satisfied by the sliding body, a rigorous LE solution for slope stability was established, accounting for the characteristics of the spatial heterogeneity and anisotropy in soil strength. Through comparative analysis of specific examples, the feasibility and effectiveness of the proposed method were validated. Additionally, this research can also be applied to thoroughly elucidate the slope failure mechanism influenced by the spatial heterogeneity and anisotropy of soil strength.

Key words: slope stability, heterogeneity, anisotropy, limit equilibrium, stresses of slip surface, progressive failure mode