ABSTRACT
Safety factors in geotechnical engineering, as in other fields of engineering, are utilised to assure sufficient safety against the uncertainty in the material properties and analysis methods. The values chosen for the safety factors depend on the available data and the engineering experience and may vary from one case to the other. In addition, safety factors do not reflect any information concerning the statistical distribution of the soil parameters and corresponding exceedance probabilities, thus yield no information about the risk of failure. The purpose of this study is to take into account the variability in the soil parameters to develop a relationship between safety factor and risk factor for the case of slope stability analysis. The risk factor is defined as the probability of slope failure. The proposed approach is demonstrated based on a slope stability analysis for a given embankment. The significance of the variability of soil parameters used in slope stability analysis was evaluated. A risk factor-safety factor relationship is developed assuming that the governing soil parameters are independent random variables. A multi-variant probability analysis is performed to obtain an optimum solution with respect to failure risk and additional cost of construction.
