Reliability Analysis of Partial Safety Factor Design Method for Cantilever Retaining Walls in Granular Soils

Abstract

Uncertainties in the geotechnical design variables and design equations have a significant impact on the safety of cantilever retaining walls. Traditionally, uncertainties in the geotechnical design are addressed by incorporating a conservative factor of safety in the analytical model. In this paper, a risk-based approach is adopted to assess the influence of the geotechnical variable and design equation uncertainties on the design of cantilever retaining walls in sand using the “partial factor of safety on shear strength” approach. A random model factor based on large-scale laboratory test data from the literature has been incorporated into the reliability analyses to quantify the uncertainty in the geotechnical calculation model. Analyses conducted using Monte Carlo simulation show that the same partial factor can have very different levels of risk depending on the degree of uncertainty of the mean value of the soil friction angle. Calibration studies show the partial factor necessary to achieve target probability values of 1 and 0.1%.