Equipment and Construction New Technology for Fire Preventing and Extinguishing Drillings in Coal Mine Goaf

In order to solve the problem of hole wall instability and wrong-place grouting pipe when fire preventing and extinguishing drillings meet crack zone and caving zone, we studied and proposed the grouting pipe technology of "not pull-out drill", tripping in grouting pipe from the inner bore of large hole drill pipe and retractable drill bit, constructed 10 fire preventing and extinguishing drillings in Dongrong Coal Mine; pore-forming success rate reached 100%, and grouting pipe success rate reached 100%; 79 units of hydraulic support after fire were withdrawn.