Tunnel support trail section additional strength manner

摘要

PURPOSE: To improve workability by mounting an auger to the boom of a running base machine through a leader, connecting a down-the-hole-hammer received in a casing steel pipe to the auger, and inserting the steel pipe into the natural ground while drilling with the hammer. CONSTITUTION: The boom 2 of a backhoe 1 is operated so as to move the lower end of a leader 12 up to the leg part of a steel support 5. Next, the built-in hole 9 of a casing steel pipe P is drilled by means of a diameter spreading bit 21 on the lower end of a down-the-hole-hammer main body 20. In this case, the bit 21 efficiently drills by a hit by compressed air of an auger speed reducer 40, rotation of the speed reducer 40, and pushing action by a feed motor 15 provided on the leader 12. After pressing the pipe P in the hole 9 keeping pace with drilling, the interior of the pipe P and the gap outside the pipe P are filled with quick hardening grout, and after hardening, it exhibits fixed strength as a supporting pile 50. Hereby, the support is prevented from sinking or the like, and can be executed safely and quickly.