Bayesian updating of uncertainties in the stability analysis of natural slopes in sensitive clays

Abstract

Safety assessment of natural slopes in sensitive clays is subjected to uncertainty due to the natural variation of soil properties, measurement and modelling errors. In order to ensure acceptable safety levels, geotechnical design codes (e.g., Eurocode 7) commonly provide frameworks for a systematic treatment of uncertainties in the safety assessment of a slope. The treatment of uncertainties in the design codes is primarily focused on the parameters directly involved in the analysis of the mechanical stability of a slope (e.g., soil strength parameters). Additional valuable contributions to the safety assessments of slopes can be also provided by information that relates indirectly to the mechanical stability of a slope (e.g., past slope performance). However, there is often a lack of systematic integration of indirect information in the existing design codes. This paper examines the integration of indirect information based on the observed past slope performance in the safety assessment of a slope. The integration is facilitated through the Bayesian framework because it provides a basis to update uncertainties in the slope stability and safety assessment, such that they are consistent to the observed slope performance. The paper examines the effects of slope survival and failure events on uncertainties in the slope stability analysis.