Research On Anti-Vibration Performance Of A Novel Three-Tube Submerged Floating Tunnel Reinforced With FRP Rigid Truss

Submerged floating tunnels are innovative transport structures that can span long and deep waters.It has many advantages over traditional bridges and tunnels,such as the ability to cross complex terrain under the sea,the fact that it is less affected by harsh environments and that it does not affect the passage of ships.The reason for this is that the majority of the load on a submerged floating tunnel is carried by the mooring system,which has large flexibility,low mass,and low damping,and the submerged floating tunnel tube is susceptible to large vibrations in the complex offshore environment due to external loads such as waves and flows,making it impossible to meet specifications for displacement and rotation of less than ±0.3m and ±0.5°.Therefore,in order to improve the anti-vibration performance of the submerged floating tunnel,a new three-tubes submerged floating tunnel concept by FRP rigid truss is proposed in this paper.And a physical section test model of the new submerged floating tunnel is developed and compared with traditional submerged floating tunnel models for c,then the anti-vibration performance of the new submerged floating tunnel is optimised and finally the dynamic response of the full-scale new submerged floating tunnel is investigated through numerical simulations.The main research results are as follows:(1)In this paper,a conceptual model of a new submerged floating tunnel is proposed,consisting of three tube bodies and a mooring system containing a FRP rigid truss.The flexible mooring system is enhanced by the FRP rigid truss,which improves the mooring stiffness of the submerged floating tunnel and anti-vibration performance of the submerged floating tunnel.The stability of the new submerged floating tunnel is further improved by increasing the structural moment of inertia and transverse rocking resistance through the triple tube structure.(2)In order to verify the anti-vibration performance,five different physical section models of the submerged floating tunnel,including the new submerged floating tunnel,were first developed.The anti-vibration performance of the five models was compared under different wave heights,wave periods and flow velocities,and the results showed that the new submerged floating tunnel has the best anti-vibration performance,which is 4-20 times better than the conventional submerged floating tunnel.(3)In order to further improve the anti-vibration performance of the new submerged floating tunnel,the design was optimized in terms of the shape,material and number of trusses installed,and it was concluded that the installation of trapezoidal trusses,steel trusses and three trusses at the same time could further improve the anti-vibration performance of the new submerged floating tunnel.(4)Based on the three-dimensional potential flow theory,a full-scale model of the new submerged floating tunnel was established using the finite element software ABAQUS,and the dynamic response of the submerged floating tunnel under different wave flow parameters was analyzed.The results show that the new full-scale submerged floating tunnel still has a high anti-vibration performance under different wave and flow loads and meets the code allowable values.