INSTABILITY MECHANISM AND PREVENTION OF ROADWAY UNDER CLOSE-DISTANCE SEAM GROUP MINING
FANG Xinqiu1，2，GUO Minjiang1，2，LU Zhiqiang1，3
(1. School of Mines，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China；2. State Key Laboratory of Coal Resources and Mine Safety，China University of Mining and Technology，Xuzhou，Jiangsu 221008，China；3. Cuijiazhai Coalmine，Yuzhou Coalmine Co.，Ltd.，Kailuan Group，Yuxian，Hebei 075713，China)
Abstract：During the process of close-distance seam group mining，mining roadway in the lower seam is affected by coal pillar in the upper seam and the adjacent working face¢s mining. Due to the severe roadway roof caving and floor heave in the working face E12505 in Cuijiazhai coalmine，the field measurement，theoretical analysis and numerical simulation are adopted to study the mechanism of roadway¢s instability. The result shows that，when the upper pillar is narrow，the roadway is under the lower levels of the pillar and the protecting pillar is not wide enough，thus the roadway is easily damaged after the adjacent working face¢s mining. It is suggested that the distance between the roadway and the upper pillar is 25 m，and the protecting pillar is 20 m，so that the roadway can be stable in strengthened support. The industrial tests have been conducted at working faces E12611 and E12504，and good results have been achieved.
