Displacement Response Of The Submerged Floating Tunnel Tube Under Dynamic Loads

The submerged floating tunnel(SFT)has provided a new traffic method for water crossing.It maintains its balance and stability by a combined effect of deadweight,buoyancy and anchoring system.As a economy and eco-friendly structure,the SFT has attracted many researchers from different countries since its conception was raised.Because of the complex underwater environment,there are still many questions of the SFT need to be solved.In this paper,a conceptual design of the SFT with a “V” type of anchorage structure was proposed,which mainly involved joint structure design,anchor system layout design,and so on.The new concept design can overcome the shortcomings of traditional anchor structure,make full use of the material of anchorage structure,increase the structure span,and make it easier to abutment and installation of the pipes of SFT underwater.It can provide reference for SFT design and construction in the future.Then,for investigating the displacement response of the SFT tube under dynamic loads,the dynamic model of SFT tube due to moving loads of constant intervals is established and is simplified as an elastically supported beam with two springs and dampings at each end.By using the Galerkin method,the displacement equation at the mid-span section of SFT can be solved,and the time-displacement response can also be gained by numerical simulation.The influence of anchor stiffness,moving loads and internals on SFT tube can be known by analyzing the simulation results.The results indicate that the anchor stiffness plays a significant role in influencing the SFT tube's displacement.And internals and velocities of moving loads can also have a great impact on the SFT tube's mid-span displacement.Moreover,the displacement response of the SFT tube under impact loads is studied by simplifying the model as an elastically supported beam with uniform supporting spacings.The influence of anchor stiffness,impact mass and impact velocity is studied by same analysis method.The present results indicate that the value of the anchor stiffness influence SFT's displacement,but this effect is limited.What's more,the impact mass and impact velocity also affect SFT's intermediate displacement obviously.