An updated empirical model for ground control in U.S.multiseam coal mines

Multiple seam interactions are a major source of ground instability in several U.S.coalfields.Empirical methods are well suited for this problem,because while the mechanics multiple seam interactions are very complex and poorly understood,many mining case histories are available for analysis.This study makes use of an updated database that includes 356 multiseam case histories,including 67 unsuccessful designs.The paper describes in detail the process used to design the study,collect the data,conduct the statistical analysis,and develop the quantitative model.The model can be used for mine planning in multiple seam situations,and has been made available as a module within the Analysis of Coal Pillar Stability(ACPS)computer program.

低透气煤层群首采关键层卸压开采采空侧瓦斯分布特征与抽采技术

通过对首采关键层留巷采空区边缘岩体结构变形破坏和裂隙演化规律的分析,揭示了"Y"型通风工作面采空侧卸压瓦斯富集区域、运移通道、瓦斯分布特征及卸压瓦斯运移规律,提出了留巷钻孔法煤与瓦斯共采新技术和新方法;在留巷内布置上下向高低位抽采钻孔直达卸压瓦斯富集区域,实现连续抽采卸压瓦斯与综采工作面采煤同步推进,通过连续高效抽采上下被卸压层的瓦斯,实现了煤矿井下直接抽采卸压瓦斯的重大突破.

沟谷区多煤层开采覆岩破坏及径流水害防治研究

沟谷地形下多煤层开采带来了严重且复杂的“裂隙发育—山体滑坡—河道堵塞—涌水加剧”链式灾害。探究沟谷地形与煤层重复采动耦合作用下的覆岩破坏特征与规律是滑坡、涌水灾害防治的关键。以西曲矿沟谷地形下多煤层开采为研究对象,综合采用集地表勘察、InSAR动态观测、降雨-径流分析和数值模拟为一体的“覆岩移动−地表变形−径流积水”分析方法,分析了沟谷区多煤层下行开采引发覆岩破坏与地表沉降的空间扩展全过程。结果表明:沟谷区下组煤充分采动后,煤层间关键层以下岩层移动范围无明显外扩特征,竖向裂隙发育,以张拉开裂为主。关键层上方岩层剪切裂隙占比明显增加,采动沉降效应与重力作用下的沟谷坡体易产生剪切滑移,甚至发生坡体下行裂隙与覆岩上行裂隙的贯通现象。重复采动造成山体滑坡形成的堆积体若阻塞河道并在汛期形成堰塞湖,则具有井下涌水风险。基于无人机倾斜摄影测量合成的高精度地形,通过降雨−径流模拟再现了山西“百年一遇”暴雨期间矾石沟流域不同历时降雨淹没范围与时间百分比,为矾石沟小流域的沟谷水灾害防范和风险评估提供了支撑,并提出了基于裂隙发育与地表淹没范围的地表径流水害综合防治方法。研究可为沟谷区多煤层开采条件下地表地质灾害防治与水资源保护提供有益参考。