Meikuang Anquan (Jul 2022)
Study on narrow coal pillar width and surrounding rock control of gob-side entry driving with large mining height and section of 6.8 m in deep coal mine
Abstract
In order to solve the problems of vicious development of surrounding rock fissures, severe mining disturbance, weak bearing capacity of narrow coal pillar and damage and failure of roadway support system of gob-side entry driving with large section of large mining height in deep coal mine, taking the small coal pillar roadway excavation of 20203 working face of Dahaize Coal Mine as the engineering background, the internal and external stress field, limit equilibrium theory, numerical calculation simulation, engineering practice are used. It is comprehensively determined that the reasonable width of narrow coal pillar of gob-side entry driving with large section of 6.8 m mining height in deep coal mine is 6.5 m, and the surrounding rock comprehensive control technology of “high-strength concrete bedding + high prestressed bolt support of roadway sides + roof flexible bolt strong support + diamond metal mesh” is proposed. The research shows that: the width of internal stress field under this geological condition is 14.4 m, the width of coal pillar crushing area after mining previous working face is 3.1 m, and the reasonable width range of narrow coal pillar is 5.8 to 8.2 m; when the coal pillar size is 6.5 to 9.5 m, the stress of the coal pillar is improved, and the elastic zone appears above the coal pillar and the roadway roof, which can give full play to the anchoring effect of bolt (cable) to ensure the stability of the roof and sides; the convergence deformation of the roadway tends to be stable 32 days after the support is completed. The maximum deformation of the solid coal wall, coal pillar wall, solid coal side roof and coal pillar side roof are 52 mm, 60 mm, 62 mm and 67 mm respectively. During the mining of this working face, the overall deformation of the roadway is in a controllable range. The 6.5 m narrow coal pillar and comprehensive control technology of surrounding rock can realize the stable bearing of narrow coal pillar and long-term effective control of surrounding rock of gob-side driving with large section of large mining height in deep coal mine.
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