| 摘要 |
PROBLEM TO BE SOLVED: To provide a construction method capable of being safely executed on a geological defective land without requiring the installation of a temporary invert and the early execution of a main invert. SOLUTION: When an upper half 10 having an approximately semicircular cross section having fixed length along the tunnel axial direction is excavated, a timbering 12 is installed, and reinforcing materials 16 are driven towards a lower section from an upper half disk 14. The reinforcing materials 16 are penetrated to the upper half disk 14 and a ground in a prearranged section forming the main invert, and driven so that front ends reach a ground 20 on the underside of the main invert. When such reinforcing materials 16 are driven and mounted to the upper half disk 14, the reinforcing materials 16 are penetrated to the upper half disk 14 and driven so that the front ends reach the ground 10 on the underside of the main invert before a lower half 22 is excavated, and a dummy invert section 24 in which the upper half disk 14 is sewn to the ground 20 on the underside of the main invert is formed. Subsequently, the lower half 22 is excavated. |
