深井近距离煤层特厚下层煤大跨度切眼布置及稳定性分析

Layout and Stability Analysis of Large-span Cutting Holes in Extra Thick Lower Coal Seam of Deep Well

近距离煤层下层煤开采受到上层煤采动的影响,对煤层工作面和切眼的布置及其稳定产生影响。针对大佛寺煤矿下层煤40109工作面大跨度切眼破坏严重、支护困难问题,通过开展切眼顶板离层量的现场实测,结合理论计算分析其破坏失稳原因,得到切眼受上层工作面开采的影响规律。结果表明:切眼顶板离层量最大达到300 mm,位于切眼两端头;回顺侧切眼顶板离层量整体上大于运顺侧;距离运顺200 m处(即回顺端头处)顶板离层量增加速率最快;说明距离4上煤层煤柱距离越小,顶板离层量和离层量变化速率就越大,受其应力集中影响较大。基于监测结果,合理优化接续工作面40111切巷布置及支护方式,顶板离层监测结果显示离层量明显减小,最大离层量为约120 mm,切眼稳定性显著增加,解决了下煤层工作面切眼失稳变形问题。研究结果为近距离煤层下层煤的切眼位置和支护设计提供依据和基础。

The mining of the lower coal in the close seam is affected by the mining of the upper coal,which has an impact on the layout and stability of the coal seam working face and the cutting hole.In view of the serious damage and difficult support of the large-span cutting hole in 40109 working face of lower coal in Dafosi Coal Mine,through the field measurement of the roof separation amount of the cut hole,combined with the theoretical calculation,the causes of its failure and instability are analyzed,and the influence law of the cutting hole by the mining of the upper working face is obtained.The results show that the maximum delamination of the cutting hole top plate is 300 mm,which is located at both ends of the cutting hole.On the whole,the delamination amount of the cutting hole roof on the reverse side is greater than that on the smooth side.The increasing rate of roof separation is the fastest at 200 m away from the running direction(i.e.at the end of the running direction).It shows that the smaller the distance from the coal pillar of upper coal seam 4,the greater the amount of roof separation and the rate of change of the amount of separation,which is greatly affected by its stress concentration.Based on the monitoring results,the layout and support mode of 40111 roadway cutting in the continuous working face are reasonably optimized.The monitoring results of roof separation show that the amount of separation is significantly reduced,the maximum amount of separation is about 120 mm,and the stability of the cutting hole is significantly increased,which solves the problem of instability and deformation of the cutting hole in the lower coal seam working face.The research results provide the basis for the location of the cutting hole and the support design of the lower coal layer in the close coal seam.