板集煤矿地下水动态特征及其影响因素分析

Analysis of Groundwater Dynamic Characteristics and Influenced Factors in Banji Coal Mine

摘要: 煤矿地下水动态变化规律系统反映了矿井疏放过程中不同含水层对此响应程度，为不同类型水害防治提供直接信息支撑。本研究以安徽省淮南煤田板集煤矿为对象，采用地下水监测与测试分析、统计分析等方法对“四含”(新生界松散层底部含水层)、9煤顶板砂岩含水层水位变化规律进行归纳和总结，并分析影响其变化的主控因素，结果表明：(1) 受9煤顶板砂岩疏放水影响，“四含”各观测孔水位持续下降，累计降深为0.64~8.7 m，为矿井主要充水水源之一，其水位降幅与涌水量变化呈对应关系；9煤顶板砂岩水位动态变化较大，降深为1.14~334.83 m，且以F104-1断层为界，断层以北富水性弱、可疏性好，而以南侧相对富水。(2) 水质特征方面，“四含”pH值7.98~9.04，矿化度2380.00~2419.00 mg/L，水化学类型为HCO₃-Cl-Na；9煤顶板砂岩含水层pH值8.41~10.87，矿化度1683.82~2300.00 mg/L，水化学类型以Cl-Na、Cl⁻·HCO₃-Na为主。导致上述变化的主要控制因素为：(1) 断层作用：F512、BF33、BF34等断层不同段的导水性差异较大(中段相对隔水、南北段具导水性)；(2) 基岩面岩性变化：井田范围内发育6处“天窗”区，导致“四含”与9煤顶板砂岩发生直接水力联系，致使“四含”水补给砂岩含水层，导致水位持续下降。

Abstract: The dynamic changes of coal mine groundwater systematically reflect the response degrees of different aquifers during the mine dewatering process, and also provide direct information support for the prevention and control of different types of water inrush hazards. Taken the Banjie Coal Mine in Huainan Coalfield, Anhui Province as the research object, this study takes methods such as groundwater monitoring, test analysis, and statistical analysis to summarize the water level change of the “Fourth Aquifer” (the aquifer at the bottom of the Cenozoic unconsolidated layer) and the roof sandstone aquifer above No.9 coal seam, and analyze the main controlled factors, and the results show that: (1) Affected by the dewatering from the roof sandstone aquifer above No.9 coal seam, the water levels of all observed holes in the “Fourth Aquifer” have been declining, with a cumulative drawdown between 0.64 and 8.7 m. As one of the main water-filling sources of the mine, the water level drawdown amplitude of the “Fourth Aquifer” has a corresponding relationship with the change of water inflow; the water level of the roof sandstone aquifer above No.9 coal seam fluctuated greatly, with a drawdown between 1.14 and 334.83 m. Taken the F104-1 fault as the boundary, the north of the fault has weak water abundance and good dewaterability; while the south is relatively water-rich. (2) In terms of water quality characteristics, the pH value of the “Fourth Aquifer” ranges from 7.98 to 9.04, the mineralization degree is 2380.00~2419.00 mg/L, and the hydrochemical type is HCO₃-Cl-Na; the pH value of the roof sandstone aquifer above No.9 coal seam ranges from 8.41 to 10.87, and the TDS is from 1683.82 to 2300.00 mg/L, and the hydrochemical types are mainly Cl-Na and Cl⁻·HCO₃-Na. The main controlled factors causing the above changes are as follows: (1) Fault action: The water conductivity of different segments of faults, such as F512, BF33, and BF34 varies greatly (the middle segment is relatively water-resistant, while the north and south segments are water-conductive). (2) The rugged bedrock surface: Six “skylight” areas are developed within the mine field, resulting in direct hydraulic connection between the “Fourth Aquifer” and the roof sandstone aquifer above No.9 coal seam, and the “Fourth Aquifer” continue to discharge toward the sandstone aquifer, with continuous decline of water level.