Reliability applied to the geotechnical design of a retaining wall

Abstract

The daily practice of designing civil engineering projects focuses its efforts on quantifying the factor of safety to ascertain whether a structure is safe or not. However, the factor of safety in itself does not reflect the probability offailure of the designed structure. This practice is deeply rooted within the geotechnical engineering field. This article shows three methods; first order second moment, point estimation, and Monte Carlo simulations. These three methods are used to estimate the probability of failure of a geotechnical structure, namely a gravity retaining wall adjacent to a slope. The probabilistic analysis allows to determine the optimal base width of the wall as a function of the construction costs. A geometrical deduction of the bearing capacity factors N_c and N_q for the slope condition is presented. Finally, results obtained from the three analysed methods are compared and some recommendations for the convenience of reliability analysis are discussed.