The work focuses on the numerical simulation of flow liquefaction, the undrained softening behavior observed in loose saturated soils of low plasticity. This phenomenon is relevant in the context of the behavior of tailings storage facilities (TSF), where it has been identified as the main cause of numerous failures of these structures. The problem is addressed by a new implementation of the constitutive Clay And Sand Model (CASM).
The formulation shows that all original inputs can be related to familiar geotechnical concepts, such as the critical state line, the state parameter, the normalized undrained peak strength, and the coefficient of earth pressure at rest. In addition, the assumptions that allow the CASM to reproduce the flow liquefaction phenomenon.
The model is applied to the simulation of the Sullivan Mine failure in British Columbia, Canada. This case study was simulated through two-dimensional (plane strain) analyses of the critical section of the TSF, assuming undrained conditions.
Results show that the rise of a dike caused a sufficiently significant deviatoric stress increase to trigger flow liquefaction, which then propagated to cause the collapse of the structure.
