Modeling of Static Liquefaction-Induced Failure of a Tailings Storage Facility (TSF)

Evaluating static liquefaction triggering and post-triggering in tailings storage facilities (TSFs) is routinely performed by means of the undrained, stress-based limit equilibrium methods. These methods are of limited use for performance-based evaluations, as no information of underlying deformation mechanisms is attained. In this study, using a well-documented static liquefaction case history, the critical state and stress-ratio controlled, bounding surface, plasticity-based constitutive model PM4Silt was evaluated to extract both the shear and volumetric responses of contractive tailings via back analysis. The results highlight the advantages of the PM4Silt model for simulating undrained loading-induced instabilities via fully coupled, staged construction analyses using FLAC software. Lastly, the PM4Silt simulations were used to inform large-strain Material Point Method (MPM) simulations and to estimate the runout mobility following static liquefaction. The results highlight the continuous strength degradation under very large deformations of contractive tailings following undrained yielding.