Analysis of the EFARC non-pillar mining stope: roof failure and overlying pressure in inclined coal seams

Abstract

During the process of coal mining, there is a violent appearance of mining stress when the initial weighting occurs. To guarantee the safety of the gob-side entry formed automatically by roof-cutting (EFARC) in an inclined coal seam, a study was conducted on the initial weighting mechanism and appearance characteristics through field monitoring and theoretical analysis. The findings reveal that, upon the initial breaking of the main roof in the non-pillar mining stope of an inclined coal seam, the deflection of the thin plate structure exhibits asymmetric distribution, with the maximum position situated in the middle-upper part of the thin plate. As the main roof thin plate reaches its limit interval, the tensile fracture first occurs in the middle-upper part of the coal wall in front and back of the stope. Once broken, the thin plate changes to a simply supported state. The analysis of field data reveals that the mine pressure in the non-pillar stope of EFARC shows an asymmetric weighting phenomenon. The periodic weighting interval at the ends of the working face increases, and the weighting intensity decreases. These results can serve as theoretical support for controlling mine pressure in non-pillar mining through EFARC in inclined coal seams and can serve as a basis for further investigations in this area.