A study on factor of safety evaluation in slope stability analysis

Slope stability analysis is commonly performed by using engineers’ experience to locate the critical failure surface. Hawever, due to the limitation of most existing software and the engineers’ experience, the failure surface so determined is not necessarily the critical one. In the present study, a newly developed software, SLOPE 2000, is used to locate the critical failure surface which can be both circular and non-circular. Comparisons between circular and non-circular failure surfaces and between 2D circular and 3D spherical failure surface analyses are performed in this study for various slope angles, soil parameters and external loads. It is demonstrated that non-circular failure surface is always more critical than circular one for 2D analysis. Furthermore, 3D analysis for spherical failure surface is also found to give larger factor of safety than the corresponding 2D analysis, There are also major differences in the failure mechanisms between 2D and 3D analyses. These findings should be noted in Slope stability assessment and design.