TUNNEL CONSTRUCTION METHOD AND SHIELD MACHINE FOR USE THEREIN

PROBLEM TO BE SOLVED: To provide a tunnel construction method which facilitates reaming and contraction of a cross section of a tunnel to shorten a construction period and reduce construction costs, and to provide a shield machine for use in the method. SOLUTION: The shield machine is provided with a cylindrical skin plate 4 forming a peripheral portion thereof, a cutter 2 arranged on a front portion of the skin plate 4, for excavating a standard shaft, and a copy cutter 3 for excavating a reamed shaft. The cutter 2 has the rod-shaped copy cutter 3 mounted therein in a manner protrudable in a direction orthogonal to an excavating direction. The shield machine 1 is comprised of a plurality of pressing jacks 9 circumferentially arranged inside a rear portion of the skin plate 4, a reaming member 5 which forms part of the skin plate 4 in a manner protrudable in a reaming direction of the reamed shaft, a tail plate 7 which forms part of the skin plate 4, for sliding in the excavating direction, and a reaming skin plate 6 which is arranged on a rear portion of the machine, for forming a shielded reamed section. COPYRIGHT: (C)2005,JPO&NCIPI