REMOVING-RECOVERING METHOD OF DOUBLE-WALLED PIPE DRILLING DEVICE AND REMOVING-RECOVERING METHOD OF DOUBLE-WALLED PIPE DRILLING DEVICE USED FOR ITS METHOD

摘要

PROBLEM TO BE SOLVED: To provide a removing-recovering technology of a double-walled pipe drilling device capable of easily removing and recovering an outer member such as an outer bit and an outer pipe remaining in a drilled hole from the drilled hole, after taking out an inner member such as an inner bit and an inner rod from the drilled hole, by finishing expected excavation work. SOLUTION: A protective pipe 6 is inserted inside the outer member such as the outer bit 4 and the outer pipe 2 remaining in the drilled hole 5 after taking out the inner member such as the inner bit and the inner rod from the drilled hole by finishing excavation by the double-walled pipe drilling device for arranging the outer bit in an outer peripheral part of the inner bit. The outer member is removed and recovered from the drilled hole 5 in a state of downward pressing the protective pipe 6 by making fluid pressure act on a blocking-up part upper surface such as a blocking-up member 7 for blocking up an opening of its protective pipe 6. COPYRIGHT: (C)2007,JPO&INPIT