Analytical study on seismic response of subsea tunnels in a multi-layered seabed subjected to P- and SV-waves

The safety of subsea tunnels during earthquakes is a crucial issue for tunnel design. This study aims to derive an analytical solution to determine the seismic response of a subsea tunnel in a multi-layered seabed subjected to P- and SV-waves with normal and oblique incidences. Subsequently, the analytical solution is validated by comparing it with existing closed-form solutions and numerical solutions for specific cases. Lastly, parametric analyses are conducted. The results highlight the importance of seawater and pore water to the seismic behavior of subsea tunnels. As the seawater depth increases, the internal forces in tunnel lining generally increase when subjected to P-waves. The seismic response of subsea tunnels is insensitive to the permeability of surrounding ground but is significantly influenced by the porosity of surrounding ground. The increase in the incident angle of seismic waves brings an increase in the internal forces in the tunnel lining. The analytical solution may be used for the preliminary seismic design of subsea tunnels.