THE BEHAVIOR OF RIGID TUNNELS IN HARD GROUND DURING AN EARTHQUAKE AND DEVELOPMENT OF AN ASEISIMIC DESIGN METHOD

Even when a tunnel is built in hard ground, examination of earthquake resistance in the axial direction must be made if the tunnel has high rigidity, and it is also necessary in the transverse direction if the upper part of the tunnel enters soft ground. The authors identified these necessity analytically. Then, we proposed that the “effective ground displacement” characteristic of hard ground should be taken into consideration, and a method of structural countermesures in hard ground. Finally, we showed an example of application in an actual tunnel.