To address insufficient dynamic characterization and unsystematic multi-index integration in tailings dam risk assessment, a comprehensive measurement method coupling numerical simulation with uncertain 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 uncertain measure functions were applied for risk classification under three dam‑height scenarios (60 m, 63.5 m, and 65 m). Measured 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.

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.