Study on the Seismic Response of Long and Large Tunnel under Non-Uniform Excitations

In recent years, the underground tunnel engineering has developed rapidly, moving towards long, large, deep, new and complex structures. The seismic design of the tunnel should consider not only the conventional consistent excitation, but also the response of the non-uniform seismic excitation to the tunnel. Taking the actual Yellow River tunnel project as an example, the non-uniform seismic excitation analysis method is used to study the lateral and longitudinal seismic responses of the super-large tunnel, and the deformation characteristics of the top, bottom and waist of the tunnel are analysed. The study found that the longitudinal deformation and mechanical behavior of long tunnels are characterized by non-uniformity, inhomogeneity and asymmetry. Under the non-uniform excitation, the maximum response displacement of the top, bottom and waist of the tunnel section is larger than the displacement under the uniform action. Therefore, during the design of long tunnels, longitudinal seismic deformation should be emphasized, and the study of non-uniform load effect should be strengthened.