Research on Water-resisting Characteristics of Carbonate Rock on Top of Ordovician System in Longgu Coal Mine

RONG Huren; BAI Haibo

doi:10.3969/j.issn.1008-4495.2015.02.020

Abstract：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.