| 摘要 |
PROBLEM TO BE SOLVED: To provide a protective structural body capable of reducing projection to an inner surface side from a lining inner face of an existing tunnel, simplifying a structure, enabling the quick construction work, and ensuring clearance limit. SOLUTION: A thin segment 7 forming a protective face material of the lining inner surface is composed of a metallic frame 13 composed of main beams 14 and joint beams 15, and a metallic face material 18 hung over in the axial direction of the tunnel to cover the inside of the lining inner surface, having a thickness less than that of the metallic frame 13, or a face material of a combined structure formed by the metallic face material and concrete. The main beams 14 and the joint beams 15 are provided with segment joints 16 and ring joints 21 respectively formed of recessed parts and projecting parts.
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