The ground directional drilling and grouting technology applied to thin limestone in structural development area

The Ⅱ63 mining area of Hengyuan Coal Mine is affected by the Wenzhuang syncline structure, the geological structure conditions are complex. The syncline fracture zone and tectonic fissures are the main water-conducting channels of No.6 coal seam floor. The Carboniferous Upper Yuan Taiyuan Formation limestone aquifer group is the main source of threat to the No.6 coal seam roadway tunneling and working face mining. In order to achieve the safe mining of the Ⅱ634 and Ⅱ635 working faces, the stratum distribution, geological structure development and hydrogeological conditions of the treatment area were analyzed in detail. The grouting prevention and control scheme of ground directional horizontal drilling of coal seam floor in advance exploration is designed, including drilling arrangement, drilling trajectory, drilling structure, grout type and grouting parameters, etc. The drilling technology of inclined section in multi-sandstone aquifer, the technology of long-distance horizontal hole drilling, the technology of ensuring the penetration rate of thin-layer limestone and the technology of high pressure grouting in long distance horizontal hole are studied, the hole forming and casing running in the inclined section of multi-sandstone aquifer have been completed, with the length of the inclined section reaching 870 m; the drilling and grouting work of long distance horizontal hole has been completed, with the length of horizontal hole reaches 959.54 m; the drilling ratio guarantee of thin limestone has been completed, and the drilling ratio of L₃ limestone aquifer is more than 90%, even as high as 100%. It not only realizes the safe mining of roadway excavation and working face in the treatment area, but also improves the construction efficiency and economic benefits.