Barragens de rejeitos: estimativa do parâmetro de estado partir de Ensaios de Piezocone

Abstract

The focus of this study is the phenomenon of flow liquefaction, which occurs in saturated soils or soils with a high level of saturation and a loss of resistance during the shear phase. This phenomenon is often observed in soft silty and sandy soils, as well as sensitive clays. When hydraulically disposed within dams, the deposited tailings tend to exhibit high levels of saturation and void ratios, circumstances that favor the manifestation of liquefaction. The occurrence of this phenomenon has been identified as the main cause in several incidents of tailings dam collapses, such as the B1 Dam catastrophe in Brumadinho (MG) in 2019 and the disaster that occurred at the Fundão Dam in Mariana (MG) in 2015. Studying susceptibility to liquefaction plays an extremely important role in tailings dams, particularly when contractive characteristics are confirmed. In Brazil, liquefaction studies have been a priority due to the unique geotechnical properties of granular materials. Various methods are available to evaluate the intrinsic liquefaction potential of the soil; however, the cone penetration test with pore pressure measurements (CPTu) seems promising in the geotechnical field. It enables the direct estimation of insitu properties of deposits, including the possibility of estimating the state parameter (ψ). This research aims to compare methodologies by Robertson (2010) and Plewes et al. (1992) for estimating the state parameter in three tailings dams based on cone penetration tests (CPTu). The study obtained similar results for two dams studied and presented more distant results in another.