Abstract: A large number of engineering practices have proved that the yield conditions of geotechnical materials are nonlinear. Such nonlinearity is more evident in areas of high geostress. However, at present, nonlinear studies on the stability of reinforced soil slope are inadequate. In this paper we research the slope stability under nonlinear Mohr-Coulomb yield condition via upper bound limit analysis. By introducing new strength parameters c_t and φ_t, we obtain the calculation formulae of stability coefficient N_s of non-reinforced soil, safety coefficient F, ultimate height H₁ of non-reinforced soil, and ultimate height H₂ of reinforced soil slope with logarithmic helix as fracture surface. Good results are obtained in a computation example using MatLab. Moreover, the influences of nonlinear parameter m on shear strength index parameters c_t and φ_t are summarized. With the increase of m, φ_t decreases gradually while c_t increases at first and then decreases. In addition, the limit slope height H reduces when slope angle β increases with other conditions unchanged.

Key words: reinforced soil, slope stability, upper bound limit analysis method, nonlinear failure criterion, mathematical programming method, theory of plasticity