Stability charts for uniform slopes in soils with nonlinear failure envelopes

• Stability parameter that reflects the failure envelope nonlinearity is introduced.
• The charts do not require an iterative procedure in determining the safety factor.
• The charts can be used for slopes subjected to water pressures or seismic forces.

Based on the results of an extensive parametric study, charts were developed for assessment of the stability of uniform slopes in soils with nonlinear shear strength failure envelopes. The study was conducted using envelopes formed to represent the realistic shapes of soil nonlinear drained strength envelopes and the associated different degrees of nonlinearity. The introduction of a simple methodology to describe the nonlinear envelopes and a stability parameter, the value of which depends on the degree of this nonlinearity has made it possible to produce such charts. The presented charts are easy to use and do not require an iterative procedure when determining the safety factors. They can be used for the analysis of dry slopes, slopes subjected to pore-water pressures represented by piezometric surfaces or pore-water pressure ratios, and slopes exposed to seismic forces. Numerical examples are given to illustrate the different applications of the presented charts, as well as the importance of considering nonlinearity of the soil strength envelope in the analysis of uniform slopes.