Dynamic Responses And Vibration Control Analysis Of The Submerged Floating Tunnel Under Combined Effect Of Internal Wave And Ocean Current

Submerged Floating Tunnel(SFT) is an innovative transportation solution in waterway crossings. In some special water areas such as deep-sea, ultra-long haul water area and environmentally sensitive area, it can effectively solve the environmental problems, lower the project costs and be born with superior anti-vibration characteristics. Although no SFT has been built all over the world, its design conception has become an pretty attractive technology option competing with traditional transportation modes(as cross-sea bridge, immersed tunnel or seabed tunnel). As an innovation technique, closed SFT tube is suspended in water with the buoyancy of water and anchored to the seabed with tension leg system, which makes SFT own unique advantages among marine structural engineering.The combined force of two typical loads(internal wave and ocean current) under the marine environment is considered for this new structure, dynamic characteristics and mechanical behavior of the SFT under combined load is investigated, and its vibration response and control based on proposed engineering is analyzed, the details as follows:(1)Stratified ocean internal wave flow field is established based on potential flow theory of function, to which ocean current flow field is superimposed to form a combined field. The joint force under internal wave and ocean current is considered with Morison formula to establish the nonlinear oscillation mathematical-physical model of tunnel-fluid interaction. Corresponding vibration differential equation are solved numerically by Galerkin method to study multimodal dynamic response behaviors of SFT under the combined effect of internal wave and ocean current and the single effect of ocean current.(2)According to dynamic response characteristic of SFT proposed project under the joint effect, effective damping measure is put forward with the inherent properties of tunnel itself and combined load. Firstly, beam mode of the tunnel tube is built, the tunnel tube is modeled as a beam with a superposition of simple and rigid beams, whose vibration shape is approximated by the combination of a flexural sine mode and a rigid body mode. Then, the relationship between tunnel structure and combined load is established, controlling the free vibrations other than the forced vibrations of the SFT induced by the internal wave and ocean current loads to achieve the goal of vibration control. Finally, the effectiveness of the damping measure is verified and evaluated by analyzing the vibration response of SFT proposed project, and reference suggestions are made for the structure design of SFT.