关键词: 厚硬顶板, 矿压特征, 预裂爆破, 切顶卸压

Abstract: Disaster induced by high-intensity weighting of hard roof becomes increasingly drastic in the past decade. For promising safe mining in such longwall faces, influence of roof cutting and stress releasing on mining pressure occurrence is analyzed in the present paper. 14141 longwall face of Jiulishan mine is affected by faults with large drop. Besides, main roof of the coal seam is hard. High-intensity fracturing of the hard roof may lead to fault activation, which dredges the water channel between longwall face and floor aquifer, and further cause water inrush accident. After roof pre-blasting, a vertical fracture is produced and the internal stress work rate needed to drive fully fracturing of main roof is decreased. Thereafter, limit span of the main roof becomes small. Support resistance during roof weighting is in direct proportion to the limit span of main roof. That means roof cutting can effectively drop weighting intensity of hard main roof. Blasting holes are drilled in the open-off cut and main gate. After blasting, vertical fractures are produced along dip and strike directions respectively, in the main roof of the open-off cut and main gate. Field measurements demonstrate weighting span is decreased and weighting intensity is weakened after roof cutting.