Abstract: The risk of dam-breaking accidents in tailings ponds is high，and there is still no effective prediction mechanism for dam-breaking sand flow. Based on the DL Breach model，a calculation method of dam-break sand flow in tailings reservoir is proposed. According to the nature of sand flow discharged from tailings reservoir，combined with the engineering experience and specifications of dam-break of tailings reservoir，the movement model of dam-break sand flow is established，the main influencing parameters in the process of dam-break are calculated，and the evolution law of submerged range and submerged depth of discharged sand flow is analyzed. The results show that the accumulation depth of the sediment discharge flow under the dam break increases first and then decreases. The submerged depth of the sediment dis⁃ charge flow in the drilling channel valley is large，and the deposition is more，and the maximum accumula⁃ tion depth is 2.48 m. As the distance from the initial dam gradually increases，the maximum submerged depth at the downstream 3# bridge does not exceed 1 m，and the overall safety risk is controllable. The nu⁃ merical simulation of tailings dam break using this model can predict the possible disasters caused by tail⁃ ings dam break，which has guiding significance for the safe operation of tailings dam.

Key words: tailings dam break, DL Breach model, sand discharge flow, submerged area, submerged depth