煤炭资源开采过程中地下水资源破坏严重，是煤炭绿色开采过程中的难题，煤矿地下水库可有效保护矿井水和提高水资源循环利用。为阐明煤矿地下水库水体净化机理，测定了神东大柳塔煤矿地下水库原位进出水水样水质指标，结合相关性、主成分分析等统计学方法与舒卡列夫分类、Piper三线图等水化学分析方法和离子比值法，分析了地下水库水体水化学特征及其形成机制。结果表明：煤矿地下水库自净化效果显著，出水的固体悬浮物、浊度、电导率和溶解性总固体等指标明显降低，化学需氧量、Fe3+、Mn2+平均去除率可分别达到42%、89%、94%；水化学类型由进水的Ca2+·Na+ - Cl-·SO42-型逐步向出水的Na+·Ca2+- Cl-·SO42-型转变，水库净化过程中发生了阳离子交换；多元统计分析表明溶滤作用、混合作用、外界干扰、阳离子交换等均会影响地下水库水质的净化过程，其中溶滤作用起主导作用；水体中Na+、Ca2+、Mg2+主要来自硅酸盐矿物的溶解。

Groundwater resources are destroyed seriously during the process of coal mining activities, which is difficult to solve throughout the green coal mining. The coal mine underground reservoir effectively solves the problems of mine drainage protection and water resource recycling. In order to clarify the mechanism of water purification in coal mine underground reservoir, this paper analyzed the water hydrochemical characteristics and formation mechanism of underground reservoirs, based on the determination of water quality index of in-situ incoming and outgoing water samples in Shendong Daliuta Coal Mine, the combination of correlation analysis, principal component analysis and other multivariate statistical methods with Schukalev classification, Piper trigram and other hydrochemical analysis methods and ion ratio method. The results show that the self-purification effect of underground reservoir in coal mine is significant. The indicators of SS, NTU, EC and TDS are significantly reduced. The average removal rates of COD, Fe3+ and Mn2+ reach 42%, 89% and 94% respectively. The hydrochemical type is gradually changed from Ca2+·Na+ - Cl-·SO2-4 type of influent to Na+·Ca2+- Cl-·SO2-4 type of effluent. Cation exchange occurs in the process of reservoir purification. The results of multivariate statistical analysis show that filtration, mixing, external interference and cation exchange affect the purification process of coal mine underground reservoir water quality, among which filtration plays a leading role. Na+, Ca2+ and Mg2+ mainly come from the dissolution of silicate minerals.