The effect of strength envelope nonlinearity on slope stability computations

Engineering analysis of slope stability includes three separate but interrelated phases: (a) experimental strength measurements, (b) determination of a strength envelope that best fits the experimental results, and (c) formal limiting equilibrium analysis using the resulting strength envelopes. Studying the interrelations between these phases leads to an integrated approach to slope stability analysis. The present work uses a single experimental database that is fitted with both linear (Mohr-Coulomb) and nonlinear failure envelopes and investigates the effect of different forms of the failure criterion on slope stability computations for both 2D and 3D problems. It has been indicated that calculated minimum safety factors could be significantly overestimated by the linear approximation of a nonlinear strength envelope. The effect of neglecting strength envelope nonlinearity is more pronounced under 3D conditions than in a 2D simplification. As a result, the use of nonlinear failure criterions in slope stability analyses is recommended to account for the stress-dependent nature of the shear strength of soils.