In the excavation unit recovery mannered null shielded cylinder of the shielded

摘要

PROBLEM TO BE SOLVED: To provide a shield machine constituted by assembling an excavation unit 2 having a cutter head 22 for excavating the ground in front of a shield cylinder on the shield cylinder 1, forming the excavation unit to have a bulkhead 21 to be internally fitted into a ring body 16 fixed at the inner periphery of a front part of the shield cylinder, supporting the cutter head for contracting its diameter to size of inside diameter of the ring body or less on the bulkhead, and removing a stopper 23 for fixation of the bulkhead 21 to recover the excavation unit by letting the bulkhead leave toward the back of the ring body and improve workability in the work for recovering the excavation unit.;SOLUTION: In this shield machine, a driving source 25 for letting the cutter head 22 advance and retreat in the forward and backward directions is mounted on the bulkhead 21. A recessed part 16b which is recessed outward in the radial direction and in which an outer end part in the radial direction of the cutter head 22 is fitted by letting the cutter head 22 retreat for the bulkhead 21 while diameter of the cutter head 22 is contracted and then extending the diameter of the cutter head 22 is formed at the inner periphery of a front end part of the ring body 16.;COPYRIGHT: (C)2009,JPO&INPIT