Extremely thin coal seam is widely distributed in Zichang mining area of Yan'an.The coal is scarce in China with coking coal,and the recovery value is high;however,the mining area has no prec-edent of mining extremely-thin coal seam,and the problem of unreasonable support selection is faced in the mining process,and there are few research results in this aspect in China,so the mining face of ex-tremely-thin coal seam in Hecaogou No.2 coal mine was taken as the research object,the fracture char-acteristics and evolution process of roof overburden structure of fully-mechanized mining face in ex-tremely thin coal seam were analyzed by means of numerical simulation and theoretical analysis,and the mechanical analysis model before and after the fracture of roof rock beam was established.And a direct roof periodic fracture distance of fully mechanized mining face in extremely thin coal seam was obtained,with the reasonable working resistance of support determined.The results show that the over-lying rock could be supported quickly after the roof caving in the early mining stage of the very thin coal seam face;after reaching the limit span of the roof,the direct top and basic top break periodically,and the basic top break position is in front of the direct top break line;there is a separation space be-tween them,and they turn and sink together.The hydraulic support of the working face is mainly affect-ed by the direct top rotating load;its working load is 3 980.89 kN,and the support selection is deter-mined to be ZZ4000/6.5/13D four-column support and cover hydraulic support.By on-site testing,the support performance can be effectively utilized to meet the surrounding rock control requirements of the stope.The research results provide a certain reference for the support selection of the mining face of ex-tremely-thin coal seam in China.
关键词
极薄煤层/综采工作面/顶板结构演化/支架-围岩作用/支架工作阻力
Key words
extremely-thin coal seam/fully-mechanized mining face/roof structure evolution/support-surrounding rock interaction/support working resistance