2003 Volume 13 Pages 247-252
The Kanaya tunnel in the New Tomei Expressway employed the TBM pilot-tunneling method is under construction. These tunnels with large cross sectional area, in general, cause large deformation at the foot of top heading due to the stress concentration. In particular, the zone where the overburden depth is about 300m in mudstone layer demonstrates excessive displacement more than 100mm without convergence tendency. Considering the restriction of excessive internal and foot displacement and the reinforcement of the surrounding ground, the high tensigle strength bolts instead of rock bolts are introduced on the circumferential arrangement.
This paper describes the results and applications of the high tensile strength bolts as the countermeasures for the excessive displacement.