ABSTRACT
The outbound line (presently referred to as the right route of the inbound line) of Nihonzaka tunnel on Tomei expressway was burned in 1979, which damaged the tunnel lining. Seven people lost their lives, two were injured, and the fire spread to 173 vehicles. It is the worst fire disaster in the history of Japan’s expressways till date. The Damaged tunnel lining was reinforced using shotcrete. However, shotcrete deteriorates over time; thus, to prevent the falling of concrete pieces, a sheet cured via ultraviolet light was installed in 2004. However, owing to the constructed sheet, the back of sheet and tunnel lining cannot be inspected. In addition, the sheet manufacturers have no knowledge regarding damage with over time. Thus, we examined the safety of the tunnel. This study reports the investigation with the survey conducted for the safety evaluation of the tunnel. Consequently, we decided to investigate damage of the sheet, metals used for holding the sheet, adhesion of the anchor bolts, and adhesion of shotcrete and tunnel lining
