Research of Complete Core-drilling Technology of Coal Seam and Influence Factors on It

In order to solve the problem that coal seam can be drilled only upward but not downward in process of uncovering coal of crossheading and shaft, a core-drilling device of dual-core and single-switch was used to do core-drilling test in shafts of some mine in Shanxi province and crossheading tunnel of Licun Coal Mine of Lu'an Group. Main influencing factor of failing in down core-drilling was summarized, which was residual water in borehole. Some measures were adopted to drain the residual water, including grouting, pumping water and deslagging with pressure air in whole core-drilling process, so as to realize complete core-drilling of coal seam. It was pointed out that the sign of successful core-drilling is that a lot of dry coal dust bursts forth form drilling hole in drilling process of core-drilling device in coal seam.