| 摘要 |
PROBLEM TO BE SOLVED: To perform the secondary concrete placement with good workability at a low cost by providing a cushioning material at the inner side of the main body of a ring-shaped tube and providing a member performing the control of the occurrence of wrinkles which occur at the time of expansion of tube main body between those stated above. SOLUTION: A movable formwork 53 is installed inside a segment 51 of a shield tunnel. A tube 1 is arranged inside the movable formwork 53, the tube 1 is expanded and the gaps are clogged. A closed space formed by the segment 51, movable formwork 53, existing secondary placed concrete and tube 1 is filled up with fresh concrete and solidified to form the secondary placed concrete. The tube 1 is provided with a cushioning material 5 at the inner side of a ring-shaped tube main body 3. An inducing joint material 7 is placed between the tube 1 and the cushioning material 5, and the occurrence of wrinkles which occur at the inner side of the tube 1 during tube expansion is controlled. In this way, a closed space can be formed only by installing the tube 1 and expanding it, and thus the placement of the secondary concrete can be easily performed.
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