Investigation of the overtopping-induced breach of tailings dams

Abstract

Using a 400 g-ton geotechnical centrifuge, a centrifugal model test system was developed to investigate the overtopping-induced breach process of tailings dams. According to abrupt changes in the erosional characteristics and breach morphological evolution, the breach processes of tailings dams could be divided into three stages, namely, the initial, acceleration, and stable stages. The breach mechanisms mainly consisted of backward erosion during the initial stage, followed by rapid downcutting and widening accompanied by intermittent lateral expansion caused by the collapse of breach-side slopes until the rebalancing of the breach channel occurred. Furthermore, a detailed physical hydrodynamic model was used to simulate dam breaching. The Reynolds-averaged Navier–Stokes (RANS) equations combined with the renormalization group (RNG) k-ε turbulence model were adopted to calculate the complex hydrodynamic conditions. In addition, the model considered the sediment transport equations for bedload and suspended load, as well as the breach-side slope sliding. The governing equations of the model were computed using the finite volume method on a rectangular grid. The calculated breach hydrograph and dynamic breach evolution were consistent with the observations made using the centrifugal tests. This study can provide a scientific reference to estimate the failure process of tailings dams.