Tunnel maintenance in Japan

Recent maintenance technology and typical deformation cases of Japanese railway tunnels are presented in this paper. Inspection of tunnel lining is divided into primary inspection and secondary inspection. New technology of non-destructive inspection which is in the process of practicable inspection to make this automatic is introduced. Repair and reinforce methods of deformation tunnels are divided into: (a) countermeasures against earth pressure; (b) countermeasures for deteriorate lining; (c) countermeasures against leakage of water and frost damage; and (d) countermeasures against spalling. Moreover, three cases concerning recent typical deformation of Japanese railway tunnels are shown; one of them is the Tukayama tunnel concerning countermeasures against plastic earth pressure and the others are the Fukuoka tunnel and the Rebunhama tunnel concerning an accident caused by spalling of tunnel lining.