| Rock tunnels are generally considered to be strong structures against earthquakes
compared to surface structures. In recent years in Japan, however, several severe damages such
as the collapse of lining have occurred due to direct earthquakes. For road tunnel owners and
users, such damage is unacceptable and countermeasures are required. On the other hand, due to
budgetary constraints, it is impossible to take large-scale measures for all tunnels. The authors
therefore have reviewed the severe tunnel damage by earthquake, conducted dynamic measurement
in actual tunnels, and examined effective countermeasures against large earthquake through
laboratory test and numerical analysis. As a result, ground conditions that are prone to be affected
by the earthquake are proposed. It is also proposed that reinforcing bar in permanent lining concrete
is effective to avoid collapse of a large mass of lining concrete. |
