极近距离煤层下煤层大断面开切眼支护技术研究

Study on Support Technology of Large Cross Section Open- Off Cut in Seam under Ultra Close Distance Seam

采用数值模拟与围岩破裂分区现场实测方法对极近距离煤层下煤层大断面开切眼设计位置与支护方式进行了研究。数值模拟表明，上煤层采空区煤体一侧应力集中较剧烈影响范围向煤体侧延伸4m，向下3m；底板破坏范围深达5．6m，较完整岩层范围为3．3～5．6m；由此确定工作面预开切眼位置离上煤层采空区走向至少5m。围岩破裂分区测试表明，巷道顶板离层裂隙发育较高，超过1．8m以上为严重破裂区域，不利于锚杆锚固；巷道两帮1．5m以外煤体破裂区域煤体完整性较好；为充分利用锚杆有效长度，设计顶帮锚杆长度都采用长度为2m的锚杆。工作面开切眼施工证明，采用锚网超前支护与架棚联合支护大断面开切眼是成功的，经济效益和社会效益是显著的。

The numerical simulation and the site measuring method of the broken rock partition in the surrounding rock were applied to the study on the design location and support method of the large cross section open - off cut in a seam under the ultra close distance seam. The numerical simulation showed that the stress concentration in a side of the seam in the goaf of the upper seam seriously influenced to extend 4 meters of the seam and extend 3 meters downward. The floor failure scope was 5.6 meters in depth and the completed strata scope was 3.3 - 5.6 meters. Thus there was 5 meters in strike between the pre - open - off cut location of the coal mining face and the goaf in the upper seam. The measurements of the broken rock partition in the surrounding showed that bed separation crack development of the roof above the mine roadway was high and the crack development over 1.8m would be a serious crack zone, which would not be favorable to apply the bolt and anchor. The seam out off the seam broken zone 1.5m beyond the two sidewalls of the roadway was good in completeness. In order to fully apply the effective length of the bolt, the roof and sidewall bolt length was designed to have a bolt with a length of 2 meters. The open - off cut of the coal mining face showed that the large cross section open - off cut with the combined support of the bolt - steel mesh advance support and the square support was successful and the economic and social benefits were remarkable.