HOLE EXPANSION METHOD OF UNDERGROUND DIGGED HOLE

摘要

PROBLEM TO BE SOLVED: To avoid to give large rotation force and pulling force to a drill pipe by digging a small hole by using a drill pipe and then expanding the hole by using an impact machine on which a steel pipe is attached at a rear end thereof and which is operated by compressed air. ;SOLUTION: An opening cutter 11 is attached integrally by a rib 13 on outer periphery of an impact machine 10 which is an impact excavator which is operated by pressurized air movement and is like a circular column. First, a hole 2 having a small diameter is drilled from a ground surface on one side to a ground surface on the other side by using a drill pipe 1. Next, an impact machine 10 to which a steel pipe 12 having a smaller outside diameter than an outside diameter of an opening cutter 11 is connected is attached to a tip of the drill pipe 1 on the other ground surface. The impact machine 10 which is operated by compressed air or oil pressure is pulled in an arrow 5 direction while it is operated by the drill pipe 1. Earth and sand which is crushed in impact drilling by the opening cutter 11 advances into the steel pipe 12 from the inside of a cylinder of the opening cutter 11 and is recovered at a tail end of the steel pipe 12. Consequently, it is possible to form a curved pipe passage in the ground without giving unreasonable force and pulling force to the drill pipe.;COPYRIGHT: (C)1998,JPO