| 摘要 |
PROBLEM TO BE SOLVED: To provide a device and a method, which enable a passenger or a vehicle to safely pass through a tunnel even during the widening of the existing tunnel. SOLUTION: A high-strength protector with strength high enough to bear a rock fall, and a low-strength protector which does not give consideration to strength are used. The high-strength protector is a short passage which surrounds an upper section and a wall surface and covers only a widened and bored place of the tunnel. The low-strength protector is a short passage which surrounds an upper section and a wall surface and has a length equivalent to the approximately overall length of the tunnel. The high-strength protector is arranged astride the outer periphery of the low-strength protector. The high-strength protector is advanced accompanied by the advance of the widened and bored place of the tunnel. COPYRIGHT: (C)2009,JPO&INPIT |
