Vibration Control of the Submerged Floating Tunnel under Combined effect of Internal Wave and Ocean Current

For investigating vibration control of the Submerged Floating Tunnel (abbreviated to 'SFT') under combined effect of internal wave and ocean current on the basis of inherent characteristics of structure itself and combined loads, the tunnel tube is modeled on a beam with a superposition of simple and rigid beams, that is, the vibration shape is approximated by the combination of a flexural sine mode and a rigid body mode. By establishing combined fluid field in stable stratified ocean, the free vibrations other than the forced vibrations of the SFT induced by combined loads are controlled to achieve the goal of vibration control. Finally, the verification of vibration control measure is conducted by the dynamic response of a proposed project of SFT. The results show that the measure presented in this paper is effective, and the optimal stiffness coefficient of tension leg for vibration control is determined by load period of combined effect of internal wave and ocean current, only several preceding odd multiples of environmental load period to half of vibration period of the SFT should be considered in analyzing the dynamic response because of smaller vibration amplitudes. The conclusions in this paper provide useful discussions for vibration control analysis of the SFT and meaningful references for the study of the complicated periodical ocean environment loads around the SFTs and even other ocean strait-crossing engineering structures.