Abstract: Through simple calculation of the normal stress on slip surface and the Mohr-Coulomb strength criterion, various calculation parameters are introduced and the stresses on slip surface are properly assumed, from which the limit equilibrium solution for three-dimensional slope stability is derived based on the static equilibrium conditions that three-dimensional sliding body satisfies Meanwhile, in stability analysis of three-dimensional slope, the direction of shear stress on slip surface is also assumed based on the previous research results, and the nonstrict method, quasi-strict method and strict method are adopted for three-dimensional slope stability analysis. By comparing with the classical results, the proposed method is validated, and the differences among various methods are analyzed. It is shown that the nonstrict method yields the smallest factor of safety, i.e., a conservative result; the quasi-strict method is similar to the strict method, yielding reliable results in calculating the safety factor of slope. In the proposed method, reasonable assumptions are made for the stresses on slip surface, and the simple solution process can be easily implemented into a computer code.

Key words: three-dimensional slope, limit equilibrium, stability analysis, stress on slip surface, factor of safety