煤矿矿井水的水质形成与演化过程机理复杂，受水动力场、水化学场和微生物场等多场作用影响显著。深入研究并揭示煤矿矿井水水质形成机理与演化趋势、阐明采空区封闭后矿井水的多场耦合作用机制是矿井水污染防控与修复的理论基础。以鄂尔多斯盆地某煤矿采空区为水文地质原型，在前期研究的基础上，进一步建立了煤矿采空区积水水位回升、蓄满后水动力−水化学−微生物场(HCB)多场耦合室内相似模拟和数值模型。采空区水动力场研究结果表明基质−裂隙双孔隙模型能有效模拟采空区水位回升过程，模拟误差为9.9%，其模拟精度远高于理论预测和单孔隙模型。水化学场模拟结果与试验较为吻合，${mathrm{SO}}_4^{2-} $、${mathrm{HCO}}_3^- $和pH模拟相对误差分别为3.0%、21.0%和6.2%，模拟结果较为可靠。模拟结果显示采空区蓄水过程中水岩反应和微生物作用不明显；而蓄满后水动力几乎停滞，但水化学场和微生物场较为活跃，2号煤和3号煤层中黄铁矿的氧化反应使得${mathrm{SO}}_4^{2-} $质量浓度提升约24.6%；后期采空区水环境演化为弱酸性、厌氧还原条件，微生物降解作用凸显，将${mathrm{SO}}_4^{2-} $质量浓度从高峰值降低了6.1%。研究结果表明：采空区封闭后矿井水具有一定的“自净”能力。通过调整微生物代谢速率常数，可将${mathrm{SO}}_4^{2-} $降解比例提高到61.6%。实际工程场景中可通过补充碳源、人工建立密闭厌氧环境等强化手段实现这一目标。将多场耦合室内试验和数值模拟技术拓展到煤矿采空区积水水质形成与演化规律研究，研究结论可为煤矿区矿井水污染防治提供指导。

The formation and evolution mechanisms of coal mine water quality are intricate, significantly influenced by multiple processes such as hydrodynamics, hydrochemistry, and biodegradation. A comprehensive investigation and elucidation of the mechanisms is theoretically crucial for the prevention and remediation of coal mine water pollution. The hydrogeological prototype of a goaf in a coal mine in the Ordos Basin is choosen, and a laboratorial physical model and a coupled hydrodynamic-chemical-biodegradation (HCB) milti-field numerical model for the goaf are established, focusing the water level rises and biogeochemistry processes. The research results demonstrate the significance of multi-field coupling effects on mine water quality. The water level filling up results shows that the matrix-fracture dual-porosity model effectively matches the water level in the goaf with a simulation error of 9.9%, which is much more accurate than the theoretical and the single-porosity model predictions. The simulation results of the hydrochemical field are relatively consistent with the experiments, with relative errors of 3.0%, 21.0%, and 6.2% for ${mathrm{SO}}_4^{2-} $, ${mathrm{HCO}}_3^- $, and pH, respectively. Results from different time periods indicate that water-rock reactions and microbial activities are not significant during the water storage process. After the goaf is filled up, the hydrodynamics almost stagnate, but the hydrochemical and microbial fields are relatively active. The pyrite oxidation reactions in the No.2 and No.3 coal seams increase the concentration of ${mathrm{SO}}_4^{2-} $ by about 24.6%. In the later stage, the water environment in the goaf evolves into weakly acidic and anaerobic reducing conditions, and the microbial degradation becomes prominent, reducing the ${mathrm{SO}}_4^{2-} $ concentration from its peak by 6.1%. A certain “self-purification” ability of mine water in the goaf after closure has been confirmed. By adjusting the microbial metabolic rate constant, the proportion of ${mathrm{SO}}_4^{2-} $ degradation can be induced up to 61.6%. In actual engineering scenarios, this target can be achieved through some strategies such as supplementing enough dissolved carbon nutrient substance and artificially establishing a closed anaerobic environment. This study expands the multi-field coupling laboratorial experiments and numerical modeling techniques to the formation and evolution of water quality in coal mine water in a goaf, and the constructive conclusions can provide theoretical guidance for the prevention and remediation of coal mine water pollution.