Static Liquefaction in the Context of Steady State/Critical State and Its Application in the Stability of Tailings Dams

Abstract

AbstractMining operations produce large quantities of tailings that must be conducted and stored safely in a technical framework that reconciles economic restrictions and environmental sustainability. Unfortunately, the history of tailings deposits is marked by episodes of catastrophic failures that have caused many victims and have cost enormous material losses. This is confirmed by the recent catastrophic collapses of tailings dams that occurred in Canada (Mount Polley), Australia (Cadia) and Brazil (Samarco and Brumadinio), where the tailings that flowed downstream severely affected the environment and, in the Brazilian case, caused many casualties. Due to this alarming empirical evidence left by the mining industry worldwide, there is international concern about the stability of tailings dams and a demand to build these deposits safely from every point of view. In this scenario, the correct evaluation of the actual shear strength of the deposited tailings is crucial. The critical state soil mechanic (CSSM) and/or the steady state of deformation provide the conceptual framework for evaluating the ultimate strength mobilized by particulate materials. In the context of a performance-based design, these states are discussed, and based on them, procedures and a flow index, If, are presented to analyze the physical stability of tailings.KeywordsTailingsLiquefactionSteady state