OpenSees Analysis of a Tailings Storage Facility in Southern Tuscany (Italy)

Abstract

Besides producing raw materials essential for contemporary societies, the mining industry also generates millions of tons of waste every year. Most of this waste is represented by tailings consisting of saturated fine non-plastic soils, generally arranged in structures called tailings dams located at a short distance from the mine. These structures contain the tailings through an embankment made with the coarser fraction of residual materials. The rate of failure for these structures is high and often results in the release of the materials in the downstream territories with catastrophic consequences for the population, the environment, and the local economy. In recent decades, the use of advanced numerical models to predict the mechanical behavior of these structures, subjected to different types of loading, initial and boundary conditions, has become increasingly widespread. Contrary to the more classical methods, such as the limit equilibrium, which only determines the safety factor for stability, these advanced tools can quantify stress distributions, deformations, accelerations and pore water pressures over time. In this work, the liquefaction potential under seismic conditions of a tailings dam located in southern Tuscany was analyzed with a dynamic finite element model implemented in the OpenSees software. Three numerical analyzes were carried out with three different advanced constitutive models describing the dynamic behavior of tailings. The constitutive models were calibrated based on the results of field tests and cyclic laboratory tests carried out on reconstituted specimens.