Probability and Risk of Slope Failure

Abstract

This paper aims to demystify the use of risk assessment as a decision management tool and present a methodology that places quantitative risk assessment within reach of every geotechnical engineer, even for routine engineering assignments. In particular, we propose using quantification of expert judgment (i.e., subjective probabilities) as a practical alternative for determining probability of slope failure. The writers present a semiempirical relationship between factor of safety and annual probability of failure that permits estimation of slope failure probabilities with relatively modest effort. The case study for a tailings dam shows that risk assessment based on quantification of expert judgment provides a framework to arrive at rational management and engineering decisions related to dam safety and other geotechnical problems. Using the semiempirical relationship presented here, practicing engineers can use this helpful tool by applying their current skills.