| 摘要 |
PROBLEM TO BE SOLVED: To provide an outer form for a tunnel entrance for securing the entrance of high strength with simple construction by forming the outer peripheral shape of a crown part of the entrance without performing trowel leveling even if applying vibration with a vibrator. SOLUTION: This outer form for the tunnel entrance is provided with an outer sheathing board 5 formed in curved shape along the outer peripheral surface of the tunnel entrance 3, and an outer frame 6 framed on the outer peripheral surface of the outer sheathing board 5. A large number of openable/closable concrete placing windows 19 different in the circumferential positions are provided at the parts, almost corresponding to the crown part of the tunnel entrance 3, of the outer sheathing board 5. COPYRIGHT: (C)2004,JPO
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