| 摘要 |
PROBLEM TO BE SOLVED: To certainly receive a propulsion reaction force of a propulsion jack, corresponding respectively to a lining part for a large-diameter tunnel and a lining part for a small-diameter tunnel that is smaller in the outer diameter than the inner diameter of the lining part for the large-diameter tunnel respectively constructed at a tunnel excavating wall when a tunnel is constructed with a shield machine that is propelled with the propulsion reaction force of the propulsion jack taken at the end face of a segment. SOLUTION: A plurality of arm members are turnably hinged at their ends at specified intervals in the circumferential direction to toruslike fixing plates 2, 3 provided integrally at the inside of a skin plate 1 of a shield machine, and a propulsion jack 4 is supported at the front end of each of the arm members and the arm members are turned by operation of a driving jack for turning. On an occasion of lining a small-diameter tunnel, the arm members are turned toward the inside and the propulsion jack 4 is made to face a small- diameter segment B1, and on an occasion of lining a large-diameter tunnel, the arm members are turned toward the outside and the propulsion jack is made to face the large-diameter segment A1.
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