Numerical Simulation of Tailings Mortar Flowing from Dam Break by Variable Concentration Two-phase Flow Algorithm

Abstract

A dam break accident of tailings pond may result in serious loss of the residents' lives and property, and usually leads to surrounding environmental disaster. Accurately calculating the flowing distance and inundation range of discharged tailings is important but remains to be solved. The main feature of tailings mortar movement is that solid particles continue to sink and accumulate during the flow process, which makes the solid concentration in the mortar constantly change, thus altering the rheological properties of the mortar. Therefore, the advancement of tailings mortar is a kind of two-phase unsteady flow with variable solid-phase concentration. In conventional numerical calculations of tailings flow, the rheological parameters of the Bingham model used are given fixed values with no consideration of concentration change, resulting in inaccurate calculation results and difficulty reflecting the phenomenon of tailings sands accumulation along the way. In this paper, a variable concentration two-phase flow model is proposed and then applied to a typical tailings dam failure case. The flow features and inundation range of the tailings mortar are analyzed and are found to be basically consistent with the field investigation, which means the proposed two-phase flow algorithm is reasonable and reliable.