Study on roadway layout and surrounding rock control of isolated island panel

Abstract

During the re-mining of historical residual coal resources, the stress environment is complex, the surrounding rock conditions are bad, the mining roadway is significantly affected by ground pressure, the layout is difficult, and the safety is poor. Taking the recovery of isolated island coal pillar in 4# coal seam as the research background, based on the difference in the distribution morphology of the goaf on both sides of the isolated island coal pillar, the stress and failure law of the isolated island panel boundary are studied by numerical simulation method. (1) The peak stress difference of multiple goaf boundaries on both sides of the isolated island coal pillar is between 0.18 and 4.51 MPa. The peak stress is affected by the change of the length of the roof “cantilever beam” at the stopping line of the goaf, so that the peak stress of the goaf boundary is periodic. (2) The high stress is mainly concentrated in the center of the pillar. The peak stress at the end of each pillar is 35–40 MPa. The coal pillar bears high stress, and the stress zone of the original rock moves to the end of the coal pillar. (3) There is a plastic zone of 8–20 m at the corner of the end of each coal pillar. On the basis of the stress zone and failure zone distribution of the goaf boundary on both sides of the isolated island panel, the roadway layout of the isolated island panel is determined, that is, the air-return roadway of the isolated island panel is arranged at random, and the width of the isolated island coal pillar d1 is selected as 10 m. The transport roadway is arranged straight, and the transport roadway of the isolated island panel is in the width section area of the goaf X4103. The width d1 of the isolated island coal pillar is selected to be 8 m, and the length d5–d7 of the mining roadway layout in the width of the coal pillar is 24 m. The roadway of isolated island panel is divided into 4 areas for support control, and the drilling pressure relief technology is proposed for high stress roadway. Through the field monitoring data, it can be seen that the mining roadway can meet the requirements of isolated island coal pillar recovery, which provides reference for the layout and control of abandoned coal roadway in this mine and other mines.