| 摘要 |
PROBLEM TO BE SOLVED: To prevent the lowering of execution efficiency. SOLUTION: A method for enlarging a sectional area of the existing tunnel includes a process carrying out reinforcing work of a lining layer 12 in the existing tunnel 10 from an inside surface side, a process setting a simple protector 18 for protecting vehicle traveling, a process excavating a widening section 20 of a circular arc-shaped section by adjoining to the side of the existing tunnel, a process setting a temporary holding strut 26 by connecting the widening section 20 to the existing tunnel 10 and a process setting a temporary partition wall 28 in the widening section 20. When vehicle traffic is ensured at the widening section 20 side, the protector 18 is removed, and while removing the temporary holding strut 26, a joint between the widening section 20 and the existing tunnel 10 is formed to define an enlarging tunnel section 22. |
