Seismic response of fluid–structure interaction of undersea tunnel during bidirectional earthquake

• The viscoelastic artificial boundary, seepage and dynamic liquid pressure are considered.
• The rock mass is considered as a saturated porous medium.
• The seismic response of the undersea tunnel is determined by considering both horizontal and vertical ground motion.
• The time history curve of the displacement, acceleration and principal stress of the lining key point are analyzed.

In this study, the seismic response of the fluid–structure interaction (FSI) of an undersea tunnel in a broken fault zone during a bidirectional earthquake is examined. An undersea tunnel FSI model that accounts for the effects of the viscoelastic artificial boundary, seepage, and dynamic liquid pressure, and considers the rock mass as a saturated porous medium, is created through finite element analysis software ADINA. The seismic response of the undersea tunnel is determined by considering both horizontal and vertical ground motion and analyzing the time history curve of the displacement, acceleration, and principal stress of the lining key point. Numerical results show that (1) the maximum displacement, acceleration, and tensile stress of the lining structure are all present in the vault area; (2) the time history curves of the displacement, acceleration, and principal stress of the key points follow a similar variation law; (3) the vertical displacement of the lining structure is greater than its horizontal displacement; and (4) tensile areas generally appear in the vault and inverted arch, but the hance is in the compression state.