To counter to the threat of the Ordovician karst aquifer during the mining of 21st coal seam in Longgu Mine, systematic analysis and research were made in this paper on the lithological property, the development degree of fissures, the filling degree, the structural characteristics of pores, the water inflow from boreholes and so on of the carbonate rock on the top of the Ordovician system. Research results showed that:①There is a relative water-resisting layer with the thickness about 60 m on the top of the Ordovician system, which was composed of Badou limestone stratum with developed fissures and high filling rate and Gezhuang dolomite stratum with nondevelopment of partial fissures;②The fissure percentage of the relative water-resisting layer of BADOU stratum and GEZHUANG on the top of Ordovician system is 2% ~9% and 2% ~3% respectively, with less residual fissures in the relative water-resisting layer and abvious pressure eliminating and water blocking effect;③ The diameter of most pores of the carbonate rock on the top of Ordovician system is less than 30μm, with poor connectivity among them, small effective pore-throat ratio and bad seepage capacity under natural condition;④Drain holes are all located in faults or fractured zones, the water flowing channels such as faults and broken rock are the main zones where the relative water-resisting layer is fractured, and they are also the places need to be detected and controlled during the mining of 21 st coal seam;and⑤There is a relative water-resisting layer in 60 m thick on the top of Ordovician system in Longgu Mine, which can provide a certain protection for the safe mining of 21st coal seam.%针对龙固煤矿21煤开采受奥陶系岩溶含水层威胁的问题,系统分析研究了奥陶系顶部碳酸盐岩的岩性、裂隙发育程度、充填程度、孔隙结构、钻孔涌水量等特性。研究结果表明：①矿区奥陶系顶部存在约60 m厚的相对隔水层,由裂隙发育且充填率较高的八陡组石灰岩和部分裂隙不发育的阁庄组白云岩构成；②奥陶系顶部八陡组相对隔水层裂隙率为2%~9%,阁庄组相对隔水层裂隙率为2%~3%,相对隔水层残留裂隙较少且消压阻水作用明显；③奥陶系顶部碳酸盐岩孔隙直径绝大多数小于30μm,孔隙连通性差,有效孔喉比例小,天然条件下渗流能力较差；④出水钻孔均位于断层或者岩层裂隙发育等区域,断层、岩层破碎等导水通道是相对隔水层破坏的主要区域,也是21煤开采重点探测防治部位；⑤龙固煤矿奥陶系顶部存在60 m厚的相对隔水层,可以为21煤安全开采提供一定的保障。
展开▼
