Fracture evolution and pressure relief gas drainage from distant protected coal seams under an extremely thick key stratum  

作　　者：WANG Liang CHENG Yuan-ping LI Feng-rong WANG Hai-feng LIU Hai-bo 

机构地区：[1]National Engineering Research Center for Coal ＆ Gas control, China University of Mining ＆ Technology, Xuzhou, Jiangsu 221008, China [2]Haizi Coal Mine, Huaibei Mining Industry Group, Huaibei, Anhui 235000, China

出　　处：《Journal of China University of Mining and Technology》2008年第2期182-186,共5页中国矿业大学学报（英文版）

基　　金：Projects 2005CB221503 supported by the National Basic Research Program of China;70533050 and 50674089 by the National Natural Science Foundation of China;2005BA813B-3-06 by the National Tenth 5-Year Key Scientific and Technological Project

摘　　要：When an extremely thick rock bed exists above a protected coal seam in the bending zone given the condition of a mining protective seam, this extremely thick rock bed controls the movement of the entire overlying stratum. This extremely thick rock bed, called a ＂main key stratum＂, will not subside nor break for a long time, causing lower fractures and bed separations not to close and gas can migrate to the bed separation areas along the fractures. These bed separations become gas enrichment areas. By analyzing the rule of fracture evolution and gas migration under the main key stratum after the deep protective coal seam has been mined, we propose a new gas drainage method which uses bore holes, drilled through rock and coal seams at great depths for draining pressure relief gas. In this method, the bores are located at a high level suction roadway （we can also drill them in the drilling field located high in an air gateway）. Given the practice in the Haizi mine, the gas drainage rate can reach 73% in the middie coal group, with a gas drainage radius over 100 m.When an extremely thick rock bed exists above a protected coal seam in the bending zone given the condition of a min- ing protective seam, this extremely thick rock bed controls the movement of the entire overlying stratum. This extremely thick rock bed, called a "main key stratum", will not subside nor break for a long time, causing lower fractures and bed separations not to close and gas can migrate to the bed separation areas along the fractures. These bed separations become gas enrichment areas. By analyzing the rule of fracture evolution and gas migration under the main key stratum after the deep protective coal seam has been mined, we propose a new gas drainage method which uses bore holes, drilled through rock and coal seams at great depths for draining pressure relief gas. In this method, the bores are located at a high level suction roadway (we can also drill them in the drill- ing field located high in an air gateway). Given the practice in the Haizi mine, the gas drainage rate can reach 73% in the middle coal group, with a gas drainage radius over 100m.

关 键 词：extremely thick key stratum protective seam exploitation fracture evolution gas drainage distant borehole drilling 

分 类 号：TD8[矿业工程—矿山开采]