Abstract: In this study, a case study is conducted on the Shantou Bay tunnel and a finite element model of a seawaterseabedtunnel system is established using the ABAQUS software to investigate the seismic response and damage of subsea tunnels under various seismic excitations and seawater depths. The results are summarized as follows: (1) Considering vertical SV waves only, the stress is mainly concentrated at the arch foot and shoulder and the seawater depth exerts a minimum effect on the horizontal motion of the seabed site and the subsea tunnel. (2) Considering vertical P waves only, the overlying seawater inhibits the vertical motion of the seabed site with increasing seawater depth and the stress below the arch waist of the tunnel increases considerably. (3) Considering the delayed incidence of PSV waves, the fracture energy and damage of the tunnel exert a certain superposition effect and the stress concentration at the arch foot and arch shoulder of the tunnel is obvious. When the depth of seawater is less than 20 m, the fracture energy and damage of the tunnel are small and the SV wave is dominant; furthermore, when the depth of seawater is greater than 20 m, the fracture energy and damage of the tunnel increase considerably and the P wave is dominant. Therefore, it is essential to consider the adverse effect of seawater on the seismic safety of the tunnel.

Key words: subsea tunnel, seismic response, waterseabedtunnel coupling, damage evolution, energy dissipation characteristic