Three-Dimensional Numerical Analysis of Tailings Reservoir and Evaluation of Dam-Failure Disaster Based on Unascertained Measure Theory

To address insufficient dynamic characterization and unsystematic multi-index integration in tailings dam hazard assessment, a comprehensive measurement method coupling numerical simulation with unascertained measure theory is proposed. A pyrite tailings reservoir was taken as the case study. FLOW-3D was used to perform three-dimensional water–sediment coupled dam-break simulations, from which key dynamic parameters (maximum deposition depth and peak flow velocity) were measured. The 3DMine model was coupled to quantify inundation extent and economic losses. A four-index evaluation system was constructed, and linear unascertained measure functions were applied for risk classification under three dam-height scenarios (60 m, 63.5 m, and 65 m). Simulated results show that, as dam height increases, breach initiation advances from 39 s to 28 s, maximum deposition depth rises from 4.35 m to 5.26 m, and peak velocity increases from 14.88 m/s to 15.22 m/s. The 370 m side drift remains safe, while the 352 m side drift, concentrator plant, and office area become inundated. Risk classification yields Grade III/II for 60 m, Grade IV/II for 63.5 m, and Grade IV for 65 m. The proposed measurement-based methodology enables systematic quantitative evaluation and supports dam-height optimization and downstream disaster mitigation.