近距离上保护层开采下伏煤(岩)裂隙时空演化过程分析

1.平顶山天安煤业股份有限公司五矿,河南 平顶山 467091; 2.中国矿业大学 安全工程学院,江苏 徐州 221116

近距离上保护层; 裂隙发育; 煤(岩)变形特征; 数值模拟

Analysis of the fracture spatial-temporal development process of underlying coal(rock)through the mining of a close upper protective layer
CHEN Rong-zhu 1,TU Qing-yi 2,CHENG Yuan-ping2,LIU Qing-feng 1

(1.No.5 Coal Mine,Pingdingshan Tianan Coal Co.,Ltd.,Pingdingshan 467091,China; 2.School of Safety Engineering,China University of Mining and Technology,Xuzhou 221116,China)

close upper protective layer; fracture development; deformation characteristics of coal(rock); numerical simulation

DOI: 10.13800/j.cnki.xakjdxxb.2018.0111

备注

为研究近距离上保护层开采下伏煤(岩)的裂隙时空演化特征,以平煤五矿为例(保护层与被保护层平均层间距为8 m),利用3DEC软件模拟不同开采距离下伏煤(岩)裂隙发育及分布特征,统计被保护层穿层斜交卸压瓦斯钻孔的抽采数据并对保护层开采效果进行验证。结果 表明,随着保护层工作面的不断推进,底板岩层内裂隙逐步发育并向深部延伸; 从回采8 m开始,被保护层己16-17煤层已出现裂隙发育,当回采18 m时,己16-17煤层内横向裂隙和垂向裂隙发育明显; 然而,当回采24 m时,由于采空区上覆岩体的垮落压实作用,底板岩层内的裂隙将发生闭合现象。沿着水平方向,底板岩层裂隙依次可以分为原始状态区、高强度卸压增透区和重新压实区。随着卸压效果越来越明显,被保护层月瓦斯抽采量由2014年6月至11月逐渐增大,最大值达到每月174 400 m3; 之后,由于被保护层裂隙闭合,每月瓦斯抽采量开始降低,并逐渐稳定在每月50 000 m3左右。

To study the fracturespace-temporaldevelopment characteristics of underlying coal(rock)after the mining of a close upper protective layer,the No.5 coal mine of Pingdingshan TianAn Coal Co.Ltd was taken as an example(the average distance between the protective layer and the protected layer is 8 m).Numerical simulation was carried out using 3DEC software,and the fracture development and distribution characteristics of coal(rock)were simulated under different mining distance.Then the effect of protective layer mining was verified by the pressure-relief gas drainage data of protected layer.The results show that with the working face of protective layer advancing continuously,the fractures in underlying coal(rock)gradually develop and extend to the deep.From 8 m of the mining distance,the fractures appear in the protected layer; when the mining distance is 18 m,the transverse and vertical fissures develop obviously.However,due to the collapse of overburden rock in goaf,these fractures will be closed.In horizontal direction,the fractures in underlying coal(rock)can be divided into 3 areasincluding original state area,high pressure relief area and re-compaction area.As the effect of pressure unloading became more and more obvious,there was an obvious increase for the drainage quantity of pressure-relief gas of protected layer from June 2014 to November 2014,and the maximum value reached 174 400 m3/month; Afterwards,due to the closure of fractures in protected layer,gas drainage quantity of each month began to decrease,and gradually stabilized at 50 000 m3/month.