采动覆岩导水裂隙在其产生后的长期演变过程中，会发生导水渗流能力逐步降低的自修复现象，研究揭示导水裂隙的自修复机制对于科学指导矿区采动地下水的生态功能恢复实践意义重大。基于神东矿区补连塔煤矿12401工作面采后15 a覆岩导水裂隙自修复的工程探测结果，就采后不同层位地下水交汇混流产生化学沉淀对导水裂隙的修复降渗机理开展研究。结果表明，12401工作面采后覆岩导水裂隙直接发育至第四系松散层，已沟通多个含水层；由于浅层地下水含有较多Ca²⁺，而基岩地下水CO₃²⁻、HCO₃⁻质量浓度偏多，2种地下水在采动覆岩中交汇混流时会产生CaCO₃化学沉淀；沉淀物随水迁移并不断吸附于裂隙通道表面，发生包藏−共沉−固结的结垢过程，经过长时间的累积，最终形成具备一定抗蚀能力的结垢物或包结物，堵塞并修复裂隙。室内试验测试发现，这一过程引起的导水裂隙自修复降渗效果相比水−(气)−岩相互作用产生的效果更为稳定且快速；裂隙岩样受2种不同水质模拟地下水混流通过近2个月时间后，绝对渗透率即由0.09×10⁻¹⁵ m²降低为0.002 5×10⁻¹⁵ m²，且在水压1.5 MPa条件下也未出现明显渗透性波动。由于这种不同地下水的交汇混流主要发生在开采边界附近的裂隙岩体中，因而覆岩不同区域导水裂隙的自修复过程及效果将出现明显差异。12401工作面中部区域覆岩导水裂隙的自修复主要由降雨入渗过程引起的水−(气)−岩相互作用引起，而开采边界附近覆岩导水裂隙则由不同地下水的交汇混流反应和水−(气)−岩相互作用共同主导其自修复，因而后者对应产生的自修复效果要明显偏好。现场探测结果显示，历经15 a的自修复演变，开采边界附近覆岩在深度86.7～179.1 m范围导水裂隙已全部实现自修复，而采区中部覆岩在对应自修复区域内仍存在局部未修复现象，深度在110.0～118.6 m，由此证实了地下水交汇混流产生化学沉淀对导水裂隙的良好修复效果。

In the long-term evolution process after the development of the water-conducting fractures in overburden, the self-healing phenomenon will occur, in which the water-conducting seepage capacity will gradually decrease. It is of great significance to study the self-healing mechanisms of water-conducting fractures for scientifically guiding the ecological function restoration of groundwater in mining areas. Based on the engineering detection results of self-healing of water-conducting fractures in No. 12401 working face of Bulianta coal mine in 15 years after mining, the mechanisms of repairing and reducing permeability of water-conducting fractures caused by chemical precipitation generated by the mixing of different groundwater from different layers after mining are studied. The results show that the water-conducting fractures in the overburden had directly developed into the Quaternary loose layer, which had connected multiple aquifers in the strata. Due to that the shallow groundwater contains more Ca²⁺, while the bedrock groundwater contains more CO₃²⁻ and HCO₃⁻, the CaCO₃ precipitation will be produced when the two kinds of groundwater meet and mix in the mining overburden. The sediment migrates with water and is continuously adsorbed on the fracture surface, the scaling process of inclusion co sedimentation consolidation occurs. After a long time of accumulation, the scale or inclusion with certain corrosion resistance is finally formed to plug and repair the fractures. The indoor test shows that the self-healing and permeability reduction effect of the water-conducting fractures caused by this process is stable and rapid. The absolute permeability of the fractured rock specimen is reduced from 0.09×10⁻¹⁵ m² to 0.0025×10⁻¹⁵ m² after nearly two months of mixed flow of simulated groundwater with two different water quality, and there is no obvious permeability fluctuation under the condition of 1.5 MPa water pressure. Because the confluence and mixing of different groundwater mainly occur in the fractured rock mass near the mining boundary, the self-healing process of water-conducting fractures and its effect in different areas of overburden will be significantly different. The self-healing of overburden water-conducting fractures in the middle area of No.12401 working face is mainly caused by the water-rock or water-gas-rock interactions caused by rainfall infiltration, while the water-conducting fractures near the mining boundary are dominated by the confluence mixed flow reaction of different groundwater and the water-rock or water-gas-rock interactions, so the self-healing effect of the latter should be obviously better. The field detection results show that after 15 years of self-healing evolution, the water-conducting fractures in the overburden near the mining boundary have been self-repaired in the depth range of 86.7 m to 179.1 m, while the overburden in the middle of the mining area still has local unrepaired phenomena in the corresponding self-healing area, with the depth range of 110.0 m to 118.6 m, which confirms the good repair effect of the chemical precipitation generated by the intersection and mixing of different groundwater.