On evaluating slope stability in sensitive clay -a comparison of methods through a case study

Paper in proceeding, 2019

This paper presents a comparison of four methods of analyses for slope stability for drained and undrained conditions with Mohr-Coulomb failure criteria, applied on a simplified slope along Göta River, Sweden. In addition to Limit Equilibrium Method (LEM), the methods include Discontinuity Layout Optimization (DLO), Finite Element Limit Analysis (FELA) and Finite Element Analysis (FEA), using both Strength Reduction Method (SRM) and Gravity Increase Method (GIM). The results showed very good correlation between all methods for undrained analyses, whereas the drained analyses showed a noticeable discrepancy in both the safety factor and the failure mode for small cohesion intercept between SRM and LEM. Results from the drained analyses performed with GIM were >100% higher than with SRM, or did not result in the development of a full failure mode. The main conclusions drawn from this comparative study are: 1) LEM is the least conservative method for all drained scenarios, and thus should be used with caution; 2) The failure mode for small cohesion intercepts c´ varies between the methods, implying an uncertainty in the application of the methods; 3) The use of GIM requires further study.