Practical countermeasures for road tunnels against collapse of lining caused by earthquake

Abstract

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.