ABSTRACT
Traditionally, slope stability analysis of both natural and man-made slope structures such as embankments has been performed deterministically, where the margin of safety is quantified by the factor of safety. The factor of safety, F, is calculated as the ratio between the available soil shear strength and the shear stress. However, most of the parameters used in geotechnical stability analysis are inherently uncertain. There is an increasing demand in geotechnical engineering, as in many other fields of civil engineering, to involve reliability concepts more strongly. Construction materials such as rocks and soils is represented with very high uncertainties, due to the natural geological processes that made these materials, and uncertainties due to limited soil investigations, measurement errors and limitations in parameter evaluation and calculation models add to the uncertainty related to slope stability evaluations. In this paper reliability analysis based on FORM-ARS for a thoroughly investigated slope in highly sensitive and quick clay in Trondheim, Norway, is presented. The geotechnical slope stability analysis is performed with the Finite Element code PLAXIS, as the Finite Element Method (FEM) is widely used in both structural and geotechnical engineering. FEM make the application of advanced soil models possible, which is a significant gain in geotechnics, but the high parameter uncertainty inevitably associated with geotechnics nevertheless should be included in the considerations. As a consequence the use of reliability analysis methods in combination with FEM becomes very attractive. This case study shows FORM-ARS with Finite Elements as an efficient way of handling reliability of slope stability analysis when dealing with advanced models and high parameter uncertainty.
