Abstract

Generally, it has been noted that underground structures have a consistent record of suffering much less damage thansurface facilities during earthquakes; but it is still necessar subject to earthquake loadings and to provide the appropriate m ethod for the seismic analysis of underground tunnelstructures since many types of underground structures have been and will be constructed in countries situated withinground tunnel structures are performed by using quasi-static analysis method and dynamic analysis method. Second, se ismic analyses in tunnel portals are performed by usingabove methods. The results of seismic analyses for the tunnel s tructure show that the tunnel structure conforms toground deformation and that seismic design by using the quasi-s tatic analysis method is more conservative than that byusing the dynamic analysis. The results of the dynamic FEM anal ysis for the tunnel structure show that the simplified 2-is can be adopted for seismic analysis. Finally, theresults of the dynamic FEM analysis in tunnel portals show that the force acting on the lining is largest near to thetunnel portal when an earthquake wave propagates parallel to tu nnel axis.