| 摘要 |
PROBLEM TO BE SOLVED: To provide an intermediate folding structure in a shield machine in which a front drum can be formed in a posture, in which a sharp curve tunnel can be excavated, by largely bending the front drum smoothly and surely by the simple operation of an intermediate-folding jack to a rear drum. SOLUTION: The mounting sections of intermediate jacks 5 on both sides connecting front drums and rear drums are formed at bending fulcrum sections, and the front drums are bent largely in the fixed directions to the rear drums only by elongating one intermediate folding jacks 5 without operating the intermediate folding jacks 5 on the other sides, using the intermediate folding jacks on the other sides as fulcra when the intermediate folding jacks 5 on one sides are elongated, and a sharp curve tunnel is pipe-jacked.
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