Risk-Based Slope Stability Criteria and Instrumentation and Monitoring Requirements

Risk-based design utilizing probabilistic analysis and the observational method (instrumentation and monitoring) are commonly implemented to mitigate the inherent risks and limitations associated with the deterministic Factor of Safety (FS) approach and/or in the absence of a well-defined slope stability criteria and instrumentation and monitoring requirements. However, the acceptable probability of failure as well as the instrumentation requirements and monitoring frequency are subject to the risk tolerance of stakeholders (designers, regulators, reviewers, asset owners, contractors), and their understanding of probability of occurrence and the perceived consequences (experience). As such, the acceptance criteria and associated risk level are inherently inconsistent from one slope stability project to another. A slope stability probabilistic acceptance criteria and necessary associated monitoring requirements is proposed, which includes defining the risk level and managing risk tolerance by using a matrix of evaluation and definition of consequences. The authors hope this will promote a more concise and consistent approach to assessing project risks and establishing proper instrumentation and monitoring controls to meet the observational approach requirements. This should also help owners to establish a baseline for the management of their geotechnical assets.

Keywords: Risk-based, Probability of failure, Instrumentation, Monitoring, Slope stability, Risk management.