The deterioration of the tunnel progressed, so a large-scale renewal construction and a large-scale repair construction became necessary. A repaired tunnel has been decided by the lining soundness. Evaluation method of the lining soundness is decided by the crack density. Lining reinforcement is conducted in a tunnel of the condition of mentioning.
The tunnel where the lining soundness is V-III-2
A tunnel constructed by a method supported by a sheet pile, which is a weatherable rock type and has a lining integrity degree III-1
Serpentinite, tuff, tuff breccia, phyllite, black schist, green schist, shale, mudstone, rhyolite, slate, green tuff, wathered granite, shirasu, loam, silt, talus deposit and gravel call the rock type which tends to weather. When the former construction data was confirmed, the rock which tends to weather found out that a strange document of lining concrete moves forward with weathering of a rock. The former construction data was confirmed and the geological feature heaving of the bottom tends to generate was investigated. The geological feature by which you assume that an invert of mudstone and tuff should be installed accounted for 90%. The geological features in which an invert should be installed are clay rocks (tertiary mudstone and tuff and a serpentine, etc.) and crystalline schist weathered and solfataric soil. Tunnels with remarkable deterioration of the lining soundness are tunnels where inversion is not installed in the geology where deterioration is predicted.
Construction began in Japanese expressway tunnel since 1963, and the total extension exceeded 1,643 km. The construction method of the tunnel was mainstream until 1988 by the timbering support method, then switched to NATM. (Figure 1.)
In Japanese expressway tunnel, more than 30 years after completion, there are 360 tunnels constructed with the timbering support method and 515 tunnels constructed with NATM. The deterioration of the tunnel progressed, so a large-scale renewal construction and a large-scale repair construction became necessary.