Incorporating suction in to stability charts for unsaturated soil slopes

Abstract

This paper presents charts derived from stability analyses of curvilinear slopes in non-homogeneous unsaturated soils. The charts enable quick and inexpensive stability analyses to be conducted in practice. The soils are assumed to obey the Mohr-Coulomb failure criterion. Suction effects are captured using the effective stress concept. Cohesion and the contribution of suction to the effective stress are linear functions of depth. It is shown that a stable curvilinear slope profile is uniquely governed by dimensionless parameters. The charts are presented using these dimensionless parameters and may be used in the preliminary design of stable curvilinear slopes. In general, suction has a similar influence to cohesion, and as the contribution of suction to effective stress increases, steeper curvilinear slopes become stable. An example of application is included showing the design of a curvilinear slope.