梅傲霜,曾一凡,武强,等. 西部矿区地下水系统水化学过程及其采动激发效应[J]. 煤炭学报,2024,49(6):2769−2784. doi: 10.13225/j.cnki.jccs.2023.0669
引用本文: 梅傲霜,曾一凡,武强,等. 西部矿区地下水系统水化学过程及其采动激发效应[J]. 煤炭学报,2024,49(6):2769−2784. doi: 10.13225/j.cnki.jccs.2023.0669
MEI Aoshuang,ZENG Yifan,WU Qiang,et al. Hydrogeochemical processes of groundwater system and its mining-motivated effect in mining areas of Western China[J]. Journal of China Coal Society,2024,49(6):2769−2784. doi: 10.13225/j.cnki.jccs.2023.0669
Citation: MEI Aoshuang,ZENG Yifan,WU Qiang,et al. Hydrogeochemical processes of groundwater system and its mining-motivated effect in mining areas of Western China[J]. Journal of China Coal Society,2024,49(6):2769−2784. doi: 10.13225/j.cnki.jccs.2023.0669

西部矿区地下水系统水化学过程及其采动激发效应

Hydrogeochemical processes of groundwater system and its mining-motivated effect in mining areas of Western China

  • 摘要: 煤炭资源开采会破坏含水层结构,扰动地下水系统,产生新的水循环模式。作为煤炭保供生产重心的西部矿区,高强度、规模化的开采加剧了这一扰动,使水岩作用等水化学过程更加剧烈。其背后所蕴含的地下水系统水化学的煤矿开采激发效应,是关系到煤矿安全开采预测预报精度,以及绿色开采地下水环境保护的关键科学问题。鉴于此,以西部榆神矿区曹家滩煤矿为研究实例,利用水文地球化学的原理和方法,从“是什么”、“为什么”和“怎么变”的角度,开展激发效应结果、激发效应过程以及水化学演化趋势3个方面系统性的研究。结果发现:研究区的地下水可以被分为5个聚类,聚类1代表煤矿开采后井田西翼第四系与风化基岩含水层为主的浅层地下水,聚类2代表开采前后地下水的混合,聚类3代表开采前的地下水,聚类4和聚类5主要代表开采后的延安组地下水;煤矿开采后,直罗组、延安组第4段和第5段含水层水样中HCO3–Ca和HCO3–Mg占比上升,井田西翼开采后的浅层地下水水质整体最优,各含水层水质有向好演变的趋势且对煤矿开采的响应不敏感;研究区地下水整体受控于阳离子交替吸附作用,煤矿开采前延安组第4段及以上含水层地下水受控于碳酸盐岩和硅酸盐岩的溶解作用;煤矿开采后的井田西翼浅层地下水受控于碳酸盐岩的溶解作用,直罗组、延安组第4段和第5段含水层地下水主要受控于硅酸盐岩的溶解和FeS2的氧化作用,延安组第1~3段含水层地下水主要受控于蒸发盐的溶解作用;煤矿开采加速了地下水的循环速度、加强了含水层间的水力联系,由此产生的稀释作用与矿井水处理后综合利用的措施是延安组第4段及以上各含水层水化学特征和水质演化的原因;未来应当继续做好矿井水处理后综合利用的工作,并注意直罗组和延安组第5段地下水特征有向浅层地下水演变的趋势,避免今后的涌水水源结果产生误判。

     

    Abstract: The exploitation of coal resources will destroy the aquifer structure, disturb the groundwater system and produce a new water cycle model. As the focus of coal supply and production, the western mining area is short of water resources and fragile in ecology. High-intensity and large-scale mining aggravates this disturbance and makes the hydrochemical process such as water-rock interaction more intense. The coal mining-motivated effect of groundwater system hydrochemistry behind it is a key scientific problem related to the prediction accuracy of coal mine safety mining and the protection of groundwater environment in green mining. In view of this, taking the Caojiatan coal mine in western Yushen mining area as an example, using the principles and methods of hydrogeochemistry, from the perspective of ‘what it is’, ‘why it is’ and ‘how it changes’, the results of mining-motivated effect, the process of mining-motivated effect, and the evolution trend of hydrochemistry are systematically studied. The results show that the groundwater in the study area can be divided into five clusters. Cluster Ⅰ represents the shallow groundwater dominated by Quaternary and weathered bedrock aquifers in the west wing of the mine field after coal mining. Cluster Ⅱ represents the mixing of groundwater before and after mining. Cluster Ⅲ represents the groundwater before mining. Cluster Ⅳ and Cluster Ⅴ mainly represent the groundwater of Yan’an Formation after mining. After coal mining, the proportion of HCO3–Ca and HCO3–Mg in the groundwater samples of the fourth and fifth sections of Zhiluo Formation and Yan’an Formation increased, the shallow groundwater quality after mining in the west wing of the mine field was the best as a whole, and the water quality of each aquifer has a tendency to evolve well and is not sensitive to the response of coal mining. The groundwater in the study area is controlled by the ion exchange, and the groundwater in the fourth and above aquifers of Yan’an Formation before coal mining is controlled by the dissolution of carbonate and silicate rocks. The shallow groundwater in the west wing of the mine field after coal mining is controlled by the dissolution of carbonate rocks. The groundwater in the aquifers of the Zhiluo Formation and the fourth and fifth sections of the Yan’an Formation is mainly controlled by the dissolution of silicate rocks and the oxidation of FeS2. The groundwater in the aquifers of the third and lower sections of the Yan’an Formation is mainly controlled by the dissolution of evaporated salt. Coal mining accelerates the circulation speed of groundwater and the hydraulic connection between aquifers. The resulting dilution effect and the discharge measures after mine water treatment are the reasons for the hydrochemical characteristics and water quality evolution of the aquifers in the fourth section of Yan'an Formation and above. In the future, we should continue to do a good job in the discharge of mine water after treatment, and pay attention to the trend of groundwater characteristics in the fifth section of Zhiluo Formation and Yan’an Formation evolving to shallow groundwater, so as to avoid misjudgment of the results of water inrush sources.

     

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