Multiscale Investigations of Overtopping Erosion in Reinforced Tailings Dam Induced by Mud-Water Mixture Overflow

Abstract

The overtopping failure that occurred to the reinforced tailings dam has led to devastating catastrophes, including severe environmental disasters as well as tragedy in terms of any loss of properties and life. To study the feature of overtopping erosion for the reinforced fine-grained tailings dam induced by mud-water mixture overflow, the red mud concentration of overflow, the erosion depths and erosion rate have been consistently detected and recorded by a series of physical model tests. This investigation conclusively showed that the red mud concentration for flooding over the dam slope had a nonlinear trend of first becoming larger, subsequently decreasing with the time going on in the process of tailing dam overtopping; the maximum red mud concentration achieved 19.0%. The erosion on the dam slope was shaped like a trumpet. The red mud concentration of the mud-water mixture flow affected the erosion depth significantly. The hydraulic tests simulating erosion behaviour in the reinforced fine-grained tailings were carried out with different red mud concentrations (0%, 10%, and 20%). For the mud-water mixture flow in a red mud concentration of 20%, the final erosion depth exhibited a ladder shape from the front to the trailing end (dam toe) of the tailings sample. The final erosion depths were 1.56 cm, 0.9 cm, and 0.55 cm at the front, middle, and trailing end, respectively. With the red mud concentration decreasing, the final erosion depth at the front of the tailings sample reduced significantly while increasing at the trailing end. This study brought more scientific insights into the overtopping erosion process to the reinforced fine-grained tailings dam triggered by the mud-water mixture flow at multiscale.