TUNNEL CONSTRUCTION METHOD

PROBLEM TO BE SOLVED: To provide a tunnel construction method for constructing a tunnel having large cross section by excavating the natural ground having an enlarged width part favorably without using a segment having high yield strength as a lining body of a tunnel to be precedently constructed. SOLUTION: In this tunnel construction method for constructing the tunnel 33 having large cross section, a pair of tunnels 10A, 10B are precedently constructed at an interval in the horizontal direction, and the natural ground G in the enlarged width part between the pair of tunnels 10A and 10B is excavated to communicate the pair of tunnels 10A, 10B mutually. When excavating the natural ground G in the enlarged width part after the pair of tunnels 10A, 10B are precedently constructed, a curved pipe roof 13 having a circular arc shape for supporting the natural ground G above the enlarged width part is installed from the tunnel 10A on one side toward the tunnel 10B on the other side, and a tip of the curved pipe roof 13 is made to reach the inside of the natural ground G apart from the tunnel 10B on the other side to install the curved pipe roof 13. COPYRIGHT: (C)2009,JPO&INPIT