SLOPE STABILITY ANALYSIS OF THE 1985 STAVA TAILINGS DAM FAILURE WITH FINITE ELEMENT AND MATERIAL POINT METHODS

This study investigates the stability of the Stava tailings dam, which collapsed in Italy in 1985, with advanced numerical simulations. Several scientific works mention that the failure started from the upper dam, but the development of the initial stages of the collapse are not fully understood. This study aims at investigating this aspect by coupling Finite Element simulations and Material Point method analyses to capture the behaviors of the dam from small to large displacement. Finite elements model (FEM) simulations were performed using MIDAS FEA NX to evaluate material parameter combinations and groundwater levels, utilizing data from previous research to bring the dam close to failure, characterized by a factor of safety (FoS) near 1. Parametric analyses with FEM provided a preliminary assessment of the failure surface geometry under varying material shear strength parameters and water levels within the dam, offering valuable insights into the relationship between water levels and the FOS. However, FEM faced limitations in capturing large post-failure deformations due to challenges in quantifying displacements and failure surfaces. To address these limitations, the Material Point Method (MPM) was employed. The initial stress conditions for MPM analysis were mapped from FEM simulations using Anura3D2024 software, based on data provided by previous research. MPM simulations successfully modeled large-scale displacements, enabling a more comprehensive analysis of dam failure mechanics.