EXCAVATING DEVICE

PROBLEM TO BE SOLVED: To provide an excavating device capable of continuously laying down tunnels with different diameters without forming a shaft at tunnel diameter switching position. SOLUTION: A cutter, a frame, and an erector disposed on the excavating device 11 to be positioned in a ground improvement part 16 in a modified space 12 continuously formed in the tunnel 1 and used for the excavating and the assembly of a covering 2 so far are dismounted from the body part 20 of the excavating device 11. The diameter of the body part 20 is reduced by diameter reducing jacks 25A, 25B, 25C and 25D according to the diameter of the tunnel 6 to be newly constructed, and a frame 30B suitable for the reduced body part 20, a first cutter 40, and an erector 60B are disposed on the reduced body part 20 to modify the excavating device 11. The excavation of an earth 15 and the construction of the tunnel 6 are performed by the modified excavating device 11. COPYRIGHT: (C)2004,JPO