底板承压水上底抽巷破坏特征及控制技术

Failure characteristics and control technology of bottom drainage roadway on floor confined water

针对承压水上掘进底抽巷易导致底板突水事故,底抽巷层位选取不合理将造成瓦斯抽采效率低的问题,以古汉山煤矿1508工作面底抽巷为工程背景,通过分析底板突水发生机理及其围岩塑性区分布特征,确定底抽巷合理的布置层位并提出围岩协同控制技术。现场试验表明,底抽巷围岩不均衡的塑性区明显使底板隔水层厚度变小,底板突水危险性高。底抽巷在垂向上距煤层底板12 m,水平方向上内错回采巷道8 m。采用以增强锚网索锚固体系能力、底角岩层稳定性及其护表能力为主,局部区域进行注浆加固为辅的综合方法对底抽巷进行治理。试验期间,底抽巷顶底板变形233 mm、两帮变形量变形209 mm后基本稳定;瓦斯抽放孔采出率得到明显提高,确保了工作面安全开采。

In response to the problem of water inrush accidents from the floor and low gas extraction efficiency caused by the unreasonable selection of the bottom drainage layer during the excavation of the bottom drainage roadway on confined water,taking the bottom drainage roadway of the 1508 working face in Guhanshan Mine as the research background,the mechanism of water inrush from the floor and the distribution characteristics of the plastic zone of the surrounding rock were analyzed,and the reasonable layout layer of the bottom drainage roadway was determined.The surrounding rock’s collaborative control technology was proposed,and on-site experiments were conducted.Research shows that the uneven plastic zone of the surrounding rock of the bottom drainage roadway significantly reduces the thickness of the floor waterproof layer and increases the risk of water inrush from the floor.The distance between the bottom extraction roadway and the coal seam floor is 12 m in the vertical direction,and 8 m in the horizontal direction;Adopting comprehensive methods such as strengthening the bearing capacity of the anchoring system,improving the stability of the bottom corner rock layer,adding protective surfaces,and local grouting reinforcement(or grouting anchor cables)were carried out.During the experiment,the deformation of the roof and floor of the bottom extraction roadway was 233 mm,and the deformation of the two sides was 209 mm,which remained basically stable.The extraction rate of gas drainage holes has been significantly improved,ensuring safe mining of the working face.