Development characteristics of mining fractures of overlying rock in the narrow coal pillar working face of Xiaojihan Coal Mine and the water hazard control

DUAN Hongfei; LI Zepeng; GAO Hui; LI Zhiyong; WANG Xufeng; DUAN Xiaopeng

doi:10.11799/ce202507015

Abstract：The mining face of Xiaojihan Coal Mine used 25～30 m wide coal pillars to protect the roadway,resulting in large deformation of the roadway and serious waste of coal resources.In order to further improve the recovery rate of coal resources,it was proposed to set up 10 m small coal pillars to protect the roadway.The reduction of coal pillar size will face two main problems:firstly,whether the extension of the working face length will lead to an increase in the height of the water conducting fracture zone,connecting to new aquifers,and increasing the risk of roof water damage;secondly,whether a 10 m coal pillar is competent to block the water accumulated in the goaf of the upper district sublevel.Aiming at these problems,the development characteristics of mining fractures and water hazards in the overburden of the small coal pillar working face are systematically studied.According to the empirical formula of the conduction height and the measured results,it is clear that the range of the crack-to-production ratio of the working face is 21～27,and the maximum development height of the water conduction fracture zone is 117 m.Combining with numerical simulation,the characteristics of the saddle-shaped distribution of the water-conducting fissured zone in the working face are clarified,and the development characteristics of the water conduction fracture zone under different mining parameters such as coal pillar width,working face length and mining thickness are mastered.Based on the ArcGIS platform,it is clarified that the key prevention and control areas of water hazard on the roof of the working face are 1041～2411 m and 3299～4630 m away from the open-off cut.Combining with the risk zoning of roof water hazard,a technical scheme of"exploration-drainage"of water hazard between the roof of the working face and the goaf of the upper district sublevel is proposed.