Abstract: Upper bound limit analysis method is an effective tool in solving geotechnical engineering problems. Conventional calculations in stability of slopes are formulated assuming the soils obeying a linear Mohr-Coulomb yield criterion. However, experimental evidences show that the failure criteria of almost all geomaterials are nonlinear over a wide range of normal stresses. In this paper, the soil masses of slopes are assumed to follow a nonlinear Mohr-Coulomb failure criterion. Based on the nonlinear failure criterion, the paper studies the problem of slope stability by combining the slice method and limit analysis upper bound method. The nonlinear strength parameters cohesion and internal friction angle are introduced through the tangent method. Joined influence of nonlinearity is established. The equations of equivalent in rates of external work and internal energy dissipation are established based on the joined influence. The equations of factors of safety for slope with different slide surface (straight line, broken-line, and circle) are deduced and the plastic analysis upper limit solutions are calculated well by these equations. A classical slope calculation case shows that the method is of correctness and high precision which consists with previous achievements. The new method can be used to guide the slope stability analysis based on the nonlinear failure criterion on the plastic upper limit theorem.

Key words: nonlinear failure criterion, upper bound limit analysis, factor of safety, stability factor