Limit equilibrium method with local factors of safety for slope stability

Abstract

Current design practice often involves the consideration of slope stability when the strength parameters of the soil or the pore pressures vary considerably within a slope. In these cases it is evident that, because of departures from homogeneity, the soil mass may slip along a noncircular surface and local overstress will occur if the factor of safety lies below a value of about 1.8. Overstress also occurs when a slope contains materials that activate their shear resistances under significantly different stress – strain relationships. Therefore, the objective of this paper is to describe a new limit equilibrium approach suitable for the consideration of the heterogeneous slopes. A new definition of local factors of safety distribution, not only along a trial sliding surface but also at the interfaces of wedge-shaped slices, is introduced considering the soil strain properties. The main features of the comptutational procedure are outlined. One illustrative example dealing with the stability of a heterogeneous slope is included. Key words: limit equilibrium, slope stability, local factors of safety.