下伏被保护层双重采动影响下覆岩瓦斯富集规律

下伏被保护层开采过程中,覆岩在双重采动影响下遭到二次破坏,形成不同于单层开采条件下的垮落特征,同时对采场瓦斯运移富集状态产生影响.以青东煤矿下伏被保护层开采为研究背景,采用相似模拟实验和理论分析方法,研究了采场覆岩在双重采动影响下的垮落特征和瓦斯富集规律,结果表明:在下伏被保护层双重采动影响下,采场覆岩在短时间内发生大范围运动,周期性地形成二次采动影响区;采场内原本富集稳定的瓦斯涌入二次采动影响区,造成该区域短时间内瓦斯富集并发生周期性变化.根据研究结果,在青东煤矿下伏被保护层828工作面施工高位钻孔,对瓦斯富集区进行抽采,通过分析瓦斯抽采浓度,验证了二次采动影响区的存在和瓦斯富集规律,并取得了良好的瓦斯治理效果.

Strata gas enrichment rules under double mining influence of underlying protected seam

During mining process of underlying protected seam, strata are damaged twice under double mining influence, whose caving characteristics are different from that of ingle seam mining, and gas movement and enrichment status would be influenced. Taking underlying protected seam mining of Qingdong Coal Mine as research background, strata caving characteristics and gas enrichment laws under double mining influence are researched by use of similar simulation experiment and theoretical analysis. The results show that under the double mining influence of underlying protected seam, the strata in stope do large scale movement in a short time, and the secondary mining influence areas are formed periodically. Gas stably enriching in stope flows into the secondary mining influence areas, where gas enriches in a short time with periodical change. According to the research results, high level boreholes are carried out in No.828 working face of underlying protected seam in Qingdong Coal Mine for gas drainage. The secondary mining influence areas and gas enrichment laws are verified by through analyzing gas drainage concentration, and good gas control effect is achieved.