Abstract
In pure geology, displacement and direction of faults are important concerns. On the other hand, forconstruction and maintenance of tunnels, the conditions of fractured rock and fault clay caused by faultsare taken seriously. However these faults often bring trouble to tunnel construction, since they have extensivescale, secondary faults, and form wide fractured zones in many cases. In such cases, if possible theyare kept away from the tunnel route and if the route crosses them unavoidably it is often difficult toexcavate through them.
In this paper, we will first describe the outline of the problems in survey, design, construction, andmaintenance of railway tunnels in fractured zones. Next, we will report the examples of the geological surveysfor the Rokko Tunnel and the Shin-Kanmon Tunnel. The former crosses many faults in the Rokkomountains and the latter crosses the fractured zone under the straits of Kanmon. We also will report theexample of the seismic prospecting for the Shin-Sasago Tunnel in order to foresee where the tunnel crossesthe fractured zone.
In addition, we will describe the construction methods to excavate through the fractured zone for theRokko Tunnel and Shin-Kanmon Tunnel. The Mukaiyama Tunnel was constructed by NATM, and thegreater convergence of the tunnel section was measured in the fractured zone even though rock bolts wereadded.
At last, we will report the case in which the Inatori Tunnel was damaged by a seismic fault.
