In order to assess the dynamic performance of a submerged floating tunnel (SFT) subject to flow-induced vibration (FIV) conditions in a practical engineering application, a one-way fluid–structure interaction (FSI) model consisting of multi-scale hydrodynamic solvers combined with the finite element method (FEM) is established. A typical long, large aspect ratio SFT is modeled by coupling tube, joint, and mooring components. The SFT is simulated in the time domain under currents, waves, and extreme events. FIV of SFTs with different cross-section shapes is investigated by analyzing each structure's natural frequencies, hydraulic loading frequency, and dominant modes. The results show that FIV of the SFT tube is dominated by wave conditions. The excitation of the SFT's first dominant mode by a large wave height and period should be avoided. Standing and traveling wave patterns and multi-mode response are observed during extreme events. The hydrodynamic forcing and structural dynamic response of the SFT can be effectively reduced by adopting a parametric cross-section.

Submerged floating tunnel (SFT) is a new type of promising traffic structure for the crossing of strait, ocean and fjord. This paper used a CFD method to investigate the hydrodynamic response of a 2D coupled tube-mooring system SFT under regular wave impacts. The influence of some key parameters was discussed, including submerged depth, buoyancy weight ratio (BWR), inclined mooring angle (IMA), mooring stiffness, mooring system arrangement, mooring pre-tension distribution andwave conditions. The results showthat themotion amplitudes and external forces of the SFT decrease with increasing submerged depth, but the SFT motion responses increase with increasing wave height and IMA. The influence of wave period is complicated, and the resonance of the SFT system must be avoided. Reasonable range of BWR exist, which leads to less motion response and more structural stability. Pre-tension distribution is not a key factor, and the mooring arrangement lacking vertical lines is not recommended. The influence factors on dynamic response was investigated, which provides references for the engineering practice.