Roof cutting and pressure relief technology fr gob-side entry in medium-thick coal seam of kilometer-deep mine

WANG Jinqiang; DING Kunpeng; WANG Wen; WANG Zuguang; DU Hao

doi:10.11799/ce202503006

Abstract：Aiming at the problem of severe mine pressure in the gob-side entry with small coal pillar of Pingdingshan No.12 Coal Mine,the overburden structure and its mechanical influence at the end of the working face,the principle of roof cutting and pressure relief technology and the combined blasting method of deep and shallow holes were studied,and applied in VI15-31040 working face.The research shows that the load of the coal pillar and the gob-side entry is the smallest when the cantilever length is small and the fracture position of the basic roof need to located outside the coal pillar.A deep-shallow hole combined directional control blasting method with"deep hole(explosives)-shallow hole(explosives)-deep hole(no explosives)"cyclic arrangement was proposed,and the directional fracture of hard roof was realized under the action of deep-shallow holes shaped blasting energy and control holes guidance.Combining with the geological characteristics of the working face,it was determined that the target height of roof cutting is 30.7 m,the angle of roof cutting is 15° to the side of goaf,the diameter of deep hole is 94 mm,the diameter of shallow hole is 55 mm,the spacing of borehole is 0.8 m,the position of borehole opening is 0.6 m from the side of roadway,the depth of deep hole is 32.5 m,and the depth of shallow hole is 15 m.The practice showed that the combination of deep and shallow hole directional control blasting method achieved good seaming effect,and effectively controlled the stress of gob-side roadway,which provides reference for safe and efficient mining in mines with similar conditions.