SHIELD MACHINE

摘要

PROBLEM TO BE SOLVED: To provide a shield machine capable of carrying out a long-distance excavation without replacing a cutter bit and coping with a change in the excavational situation during excavation. SOLUTION: In the shield machine provided with a rotary cutter 13 fitted with the cutter bit 12 capable of excavating the whole cross section of a shield frame, a slide bit 33 slidable in a diametral direction is mounted separately from the cutter bit 12. The slide bit 33 is positioned inward in the diametral direction in the case of the start of the excavation, and slid from an inward position in the diametral direction to an outward position to be made a new excavating bit when a cutter bit 12b on the outer periphery of the rotary cutter 13 wears away.