Numerical analysis of the fluid–structure interaction characteristics of a pontoon submerged floating tunnel

This study is intended to elucidate the mechanisms underlying fluid–structure interactions (FSIs) for a pontoon submerged floating tunnel (PSFT). To this end, a shear stress transport k-ω turbulence model was used to analyze the hydrodynamic force of the PSFT tube under the flow load. The finite element method was then used to predict the horizontal displacement of the PSFT tube under hydrodynamic action. In the calculation, the buoyancy of the PSFT pontoons was represented by an equivalent spring tension, and the fixed constraint was adopted at the shore wall of the tunnel tube. The FSI calculation results indicated that, when the flow load was larger, the pressure fluctuations of the flow field around the PSFT tube were stronger, resulting in greater dynamic effects on the horizontal direction of each tube segment. The smallest and largest deformations of the tunnel segment were observed at the mid-span and near the shore wall, respectively. It was also found that the barbell-shaped PSFT tube cross section may lead to intensify the pressure fluctuations near the tunnel tube as the flow load was increased. It is recommended that the appropriate number of pontoons and tunnel tube reinforcement can reduce the deformation of the PSFT.