Research on the static liquefaction failure of upstream tailings dams under continuous discharge conditions

Upstream tailings dams are extensively employed owing to their straightforward and economical construction methodologies worldwide. Nevertheless, they are susceptible to static liquefaction failures, wherein sustained tailings discharge (monotonic loading) stands as one of the primary triggering conditions for static liquefaction. This study centers on the Erlichong tailings dam and employs a multifaceted approach, combining field investigations, laboratory experiments, and fluid–solid coupling discrete element method. It mainly aims to ascertain the influence of tailings discharge rates, fine-grained interlayers, and drainage facilities on static liquefaction failure within the tailings dam. It is found that, higher discharge rates lead to accelerated accumulation of excess pore water pressure, rendering the tailings dam increasingly vulnerable to static liquefaction failure. Meanwhile, although in-situ mixed tailings exhibit greater susceptibility to static liquefaction than fine tailings with same initial void ratio under completely undrained conditions, the presence of fine-grained interlayers diminishes the vertical permeability of the tailings deposit in practical scenarios. Undrained conditions are established for the mixed tailings confined within the interlayers. Consequently, tailings dams containing fine-grained interlayers demonstrate heightened vulnerability to static liquefaction failure in comparison to homogeneous tailings dams. Furthermore, the incorporation of drainage facilities serves to mitigate the risk of static liquefaction, with the vertical-horizontal combined drainage scheme emerging as the optimal strategy for tailings dams with fine-grained interlayers. In summary, this study furnishes theoretical insights aimed at ensuring the secure operation of tailings dams.