陕北榆神矿区煤层开采顶板涌水规律分析

榆神矿区是我国陕北煤炭基地的重要组成部分,针对榆神矿区煤层开采顶板覆岩含水层涌水规律研究不足等问题,通过系统分析地质与水文地质结构特征,将矿区开采煤层覆岩划分为松散孔隙、基岩与风化裂隙、烧变岩孔洞裂隙4个含水层组,以及主、亚2个隔水保护层组;根据煤层采动导水裂隙与覆岩含(隔)水层组不同组合关系下的含水层涌水特征,提出了浅埋煤层侧向直接涌水、中深煤层侧向与垂向复合涌水,以及深埋煤层侧向涌水与垂向弱涌水3种含水层涌水模式;并采用数值分析方法,以榆神矿区典型矿井为研究对象,构建了采煤工作面尺度上煤层开采3种模式涌水分析模型,模拟结果显示,浅埋煤层侧向直接涌水型(凉水井井田),主采煤层为4^-2煤层,采动导水裂隙直接发育至松散含水层,工作面顶部含水层被疏干,总涌水量为47 m³/h,地下水流场受采动影响大;深埋煤层侧向涌水与垂向微涌水型(小壕兔1号井田),主采煤层为1^-2煤层,采动导水裂隙发育至基岩含水层,总涌水量为21.87 m³/h,以侧向涌水为主,由于主、亚隔水层复合保护,垂向涌水微弱;中深煤层侧向与垂向复合涌水型(曹家滩井田),主采煤层为2^-2煤层(均厚约为11 m),在分层开采条件下导水裂隙发育至基岩含水层内部,其侧向涌水量为23.17 m³/h,垂向涌水量为12.67 m³/h,地表松散含水层地下水流场变化较小,在一次采全高条件下导水裂隙突破亚隔水层,发育至风化基岩含水层底部,总涌水量增至131 m³/h,对松散含水层影响较大。此外,当导水裂隙带高度小于180 m、不能沟通风化基岩含水层时,随导水裂隙带高度增加涌水量增加幅度不大,当导水裂隙带高度大于180 m、导水裂隙揭露富水性较好的风化基岩含水层时,涌水量增加幅度较大,由此可见,抑制导水裂隙发育高度与覆岩强含水层的接触关系,是控制煤层覆岩涌水的一项重要措施。

Analysis of overlying aquifer water inrush above mining seam in Yushen mining area

Yushen mining area is an important part of the coal base in Northern Shaanxi.Aiming at the problems of insufficient research on water inrush of aquifer above the coal seam being mined in Yushen mining area,the overlying strata of the coal seam being mined is divided into four aquifer groups:loose pore,bedrock and weathering fissure,cave-fissure aquifer in burnt rock,as well as the main and sub-2 water-proof soil layers according to the typical geological and hydrogeological structure characteristics of the mining area,Three types of aquifer water inrush modes are proposed and named as“shallow lateral direct water inrush mode”,“medium-deep lateral and vertical combined water inrush mode”and“deep-buried lateral and vertical weak water inrush mode”respectively according to the water inrush characteristics of aquifers under different combinations of water-conducting fissure zone and aquifer groups.The water inrush analysis models of three coal mining modes on the scale of coal mining face are constructed,which shows that under the lateral direct loss type of shallow seam condition(Liangshuijing coal mine),the main mineable coal seam is No.4^-2,because of the water-conducting fissures directly develop to loose aquifers,the top aquifer of the mining face is dried,the total water inrush is 47 m³/h,and the mining effect on groundwater flow field is significant.In the deep-buried composite water-proof protection micro-loss type(Xiaohaotu No.1 coal mine),the main mineable coal seam is No.1^-2,the total loss of water in the aquifer is 21.87 m³/h,it is mainly in the form of lateral water inrush,although the water-conducting fissures develop into bedrock aquifers,the groundwater flow of the loose pore aquifer is basically unchanged under the protection of main and sub-soil layers.In the medium-deep lateral and vertical composite water inrush type(Caojiatan coal mine),the main mineable coal seam is No.2^-2,and the average thickness of No.2^-2coal seam is about 11 m,water-conducting fissures develop to the interior of bedrock aquifer under the condition of stratified mining of coal seam which leads to a lateral water inrush of aquifer with 23.17 m³/h and a vertical water inrush with 12.67 m³/h,the groundwater flow of loose aquifer changes little.The total water inrush increases to 131 m³/h which has a great influence on the loose aquifers when the water-conducting fissures break through the sub-aquifer and develop to the bottom of the weathered bedrock aquifer under the condition of full mining height.In addition,the total amount of water inrush increases slightly with the increase of the height of the water-conducting fissures when the height of water-conducting fissure zone is less than 180 m and does not extend to the weathered bedrock aquifer.However,the water-conducting fissures expose weathered bedrock aquifers with better water-rich when the height of the water-conducting fissures is greater than 180 m,which leads to a larger increase in the water inrush of aquifers.It can be seen that it is an important measure to control the water inrush by restraining the contact relationship between the height of water conducting fracture and the overburden aquifer with significant water yield.The research results of this paper provide a scientific basis for the prevention and control of roof water disaster and the coordinated protection of water resources in the arid and semi-arid mining areas of Western China.