Analyzing the role of soil water retention curve in slope stability for differently structured soils

 We analyzed the mechanical and hydrological effects of soil water retention curve (SWRC) models on the slope stability analyses of soils with unimodal and bimodal behavior.  We used three different SWRC models, two bimodal models (Ross&Smettem and Dexter) vs. the traditional van Genuchten model, to evaluate the Factor of Safety (FS) of a simple designed hillslope, based on the Bishop approach for unsaturated soils. Two formulations for term were also considered.  Results indicate that in cases of clayey soils, changes in FS obtained with different SWRC models especially at soil moisture values within the residual zone. In sandy soils the choice of formulations can be more important. The variation decreases as the slope conditions get worse, i.e. slope angle increases or friction angle decreases