Drilling method for producing a large-diameter hole in rock with extendable drill stem and indirect compressed-air flushing

摘要

The invention relates to a drilling method with indirect compressed-air flushing for producing a large-diameter hole (2, 65) in rock with a drill head (10) which is driven via an extendable drill stem by a drilling machine (1) set up outside the borehole and receives the cuttings/air mixture via a receiving opening (14, 99). The object of the invention is to provide a method of the generic category mentioned at the beginning with which the cuttings, even in hard rock, can be removed from considerable drilling depths during the drilling sequence without conveying members susceptible to wear and without the aid of electrical power, control or signal lines next to the drill stem and without additional steps of the method. This object is achieved according to the invention in that longitudinally displaceable packing (6) is inflated on a drill pipe (5) near the drill head (10) under the action of the compressed flushing air, is set against the borehole wall (23) and, by alternate release and re-application of the pressure of the flushing air, is shifted into a position advancing in the drilling direction (arrow 75) and is set against the borehole wall (23) again. <IMAGE>