ABSTRACT
The Kawabe Daiichi tunnel has one traffic lane in each direction, with an evacuation tunnel 4.50 meters in diameter nearby. In this project, the current tunnels will be remodeled to a twin tunnel system, by enlarging the evacuation tunnel for use as a new in-bound road tunnel, keeping it open 24 hours a day. The new tunnel will be full-face bored using a blasting technique. The cutting face used for enlarging the tunnel’s width has a hemi-spherical shape. For weak ground, the support will be structured in the shape of a ring and the cross section be closed early to maintain tunnel stability mechanically. Lining concrete to be used will be medium fluidity. The concrete is placed automatically with the use of a computer controlled and compacted with a form vibrator, to make the placed concrete uniform and to maximize the automation of lining construction.
