Assessing Static Liquefaction Triggers in Tailings Dams Using the Critical State Constitutive Models CASM and NorSand

Abstract

Static liquefaction-induced failure in tailings dams can result in extensive economic and environmental damage. In practice, the use of constitutive models capable of capturing this phenomenon and assessing structures susceptible to liquefaction is increasing. Numerous constitutive models exist and have been applied to model static liquefaction of tailings materials, but the extent of the influence exerted by the choice of constitutive model on analysis outcomes remains to be determined. This study addresses this uncertainty by employing the Clay and Sand Model (CASM) and NorSand models to analyze the well-documented case of the B1 dam failure in Brazil. Initially, a back analysis of the failure was conducted, and further analyses were carried out by simulating hypothetical triggers: crest loading and increased gravity. The influence of the adopted constitutive model on results was analyzed through the failure mechanisms generated, stress paths, and levels of disturbances necessary to trigger liquefaction. Both models produced compatible failure mechanisms, with slight differences observed in the level of disturbance required to trigger liquefaction. The results obtained from the B1 case indicate that the most important aspect related to the constitutive model in assessing structures susceptible to static liquefaction lies in the constitutive model's capacity to represent the sudden strength loss due to pore pressure generation, while the particular formulations employed in each method tend to be a secondary consideration in the analysis.