National Engineering Research Center of Coal Mine Water Hazard Controlling, Suzhou University
Key Laboratory of Mine Water Resource Utilization of Anhui Higher Education Institutes, Suzhou University
College of Earth Science and Engineering, Shandong University of Science and Technology
Huaibei Mining Co., Ltd.
Hengyuan Coalmine of Wanbei Coal-Electricity Group Co., Ltd.

淮北煤田下组煤开采，主要威胁水源是煤层底板灰岩水(包括石炭系太原组及奥陶系灰岩水)，淹井事故时有发生。针对底板灰岩水害治理，目前多采用地面定向钻高压注浆技术，对煤层底板太原组第3层薄层灰岩(简称“三灰”)进行区域性加固改造，以封堵三灰岩溶裂隙并阻断穿过三灰的垂向导水通道。但大规模高压注浆工程的实施，受注含水层地下水流场会受到干扰，在大量浆液析出水的耦合作用下，地下水化学场必然会受到严重扰动。以淮北煤田桃园煤矿太原组灰岩含水层(简称“太灰水”)为研究对象，基于常量组分监测数据统计、Piper图、离子组合比及饱和指数分析，开展了区域注浆前−注浆期间−注浆结束后(即区域注浆前−中−后“三时段”)太灰水水文地球化学演化规律研究。结果表明：① 三时段太灰水中Na++K+、${rm{HCO}}_3^ - $、Cl−先减小后增大，Ca2+、${rm{SO}}_4^{2 - } $和pH先增大后减小，Mg2+、TDS则整体减小。注浆治理区域Ca2+、${rm{SO}}_4^{2 - } $相对较高，碱度较大，而Na++K+、${rm{HCO}}_3^ - $含量相对较低。注浆前以SO4·Cl−Na和SO4·Cl−Na·Ca(混合型)为主，区域注浆“中−后”时段，太灰水则以SO4·Cl−Na·Ca和SO4·Cl−Na型居多，混合型水占比增大。② 注浆期间，太灰水中碳酸盐、硫酸盐溶解作用、脱硫酸作用和阳离子交换作用减弱，方解石、白云石的溶解作用增强，同时浆液析出水的混合影响作用明显。注浆结束后，碳酸盐、硫酸盐溶解作用、脱硫酸作用和阳离子交换作用逐渐增强，方解石、白云石的溶解作用逐渐减弱，浆液析出水的混合影响作用减弱。注浆结束1 a后水化学作用逐渐向注浆前状态恢复，但仍未恢复至注浆前状态，可知区域注浆治理对太灰水化学场扰动影响比较明显。③ 太灰水中白云石、方解石饱和指数较大，多呈现沉淀状态；石膏、岩盐饱和指数较小，多以溶蚀状态存在。三时段太灰水中方解石、白云石和石膏3种矿物饱和指数均呈先增加后降低趋势，其中白云石表现较为明显，而岩盐饱和指数变化不明显。多数矿物饱和指数与pH呈较强的正相关性，而石膏饱和指数则与TDS呈较强正相关性。④ 由于高pH的注浆浆液析出水的混扰，原来离子间平衡被打破，从而导致区域注浆以来太灰水常量指标相关性降低，且注浆结束后比注浆期间相关性更低。

The main threat source of coal mining in the lower formation of Huaibei Coalfield is limestone water from the coal seam floor (including the Carboniferous Taiyuan Formation and the Ordovician limestone water), and some well flooding accidents occur from time to time. For the control of water disaster in the limestone floor, at present, the ground directional drilling high-pressure grouting technology is mostly used for carrying out the regional reinforcement and reconstruction of the third layer of thin limestone (referred to as “three ashes”) in the Taiyuan Formation of the coal seam floor. Therefore, it seals the karst cracks of the three ashes and blocks the vertical water channel passing through the three ashes. However, with the implementation of large-scale high-pressure grouting project, the groundwater flow field in the injected aquifer will be disturbed. Because of the coupling effect of a large amount of slurry water, the groundwater chemical field will inevitably be seriously disturbed. Taking the limestone aquifer of the Taiyuan Formation (hereinafter referred to as “Taihui water”) in the Taoyuan Coalmine of the Huaibei Coalfield as the research object, based on the constant component monitoring data statistics, Piper diagram, ion combination ratio, and saturation index analysis, this paper studies the hydrogeochemical evolution law of the Taihui water before grouting, during grouting and after grouting (i.e. “three periods before, during and after regional grouting”). The results show that ① in the three periods, Na++K+, HCO3 −, Cl− in the Taihui water first decrease and then increase. Ca2+, SO4 2− and pH values first increase and then decrease, while Mg2+, TDS decrease as a whole. In the grouting control area, Ca2+ and SO4 2− are relatively high and alkalinity is relatively high, while Na++K+ and HCO3 − are relatively low. Before grouting, SO4•Cl−Na and SO4•Cl−Na•Ca (mixed type) are the main types. Since regional grouting, SO4•Cl−Na•Ca and SO4•Cl−Na are the main types in the Taihui water, and the proportion of mixed water increases. ② During grouting, the dissolution of carbonate and sulfate, the desalfation and the cation exchange in the Taihui water are weakened, the dissolution of calcite and dolomite is enhanced, and the mixing effect of the precipitates water of cement slurry is obvious. After grouting, the dissolution of carbonate and sulfate, desulphation and cation exchange are gradually enhanced, the dissolution of calcite and dolomite is gradually weakened, and the mixing effect of precipitates water is weakened. One year after the completion of grouting, the hydrochemical effect is gradually recovered toward the state before grouting, but it has not yet recovered to the state before grouting. It can be seen that the regional grouting treatment has a relatively obvious impact on the disturbance of the chemical field of the Taihui water. ③ The saturation index of dolomite and calcite in the Taihui water is large, and most of them are in precipitation state. The saturation index of gypsum and rock salt is small, and they mostly exist in the state of dissolution. In the three periods, the saturation indexes of calcite, dolomite and gypsum in the Taihui water increase first and then decrease, in which dolomite is more obvious, while the rock salt saturation index does not change significantly. The saturation index of most minerals has a strong positive correlation with pH value, while the saturation index of gypsum has a strong positive correlation with TDS. ④ Due to the mixing of the water from the grouting slurry with high pH value, the original ion balance is broken, which leads to the reduction of the correlation of the conventional indicators of the Taihui water since the regional grouting, and the correlation is lower after the grouting than that during the grouting.

安徽省高校优秀科研创新团队资助项目(2022AH010081)；安徽省公益性地质资助项目(2023-g-1-11); 安徽省自然科学基金青年资助项目(2008085QD175)

郭艳，桂和荣，魏久传，等. 区域注浆影响下煤层底板太原组灰岩水水文地球化学演化规律[J]. 煤炭学报，2023，48(8)：3204−3217.

GUO Yan，GUI Herong，WEI Jiuchuan，et al. Hydrogeochemical evolution law of Taiyuan Formation limestone water under coal seam floor caused by the influence of regional grouting[J]. Journal of China Coal Society，2023，48(8)：3204−3217.