Theoretical Research On Key Parameters Of Structure Selection About Submerged Floating Tunnel

The Submerged Floating Tunnel(SFT for short)is a new symbolization of crossing tunnel conception,which is used to cross rivers,lakes,bays,straits or other appropritate waterways.This type of tunnel is not constructed in the middle of formation or through formation.It is encompassed with water,which is quite different from the traditional tunnels.The mechanical principle of SFT is keeping balance between the self-gravity and the buoyancy force with the aid of a specialized,which can achieve the purpose of making SFT floating in given depth below free surface.The merits of the innovative traffic structure as: The total length of an SFT is obviously shorter than anyother ordinary submarine tunnel;Unaffected by extreme weather conditions;The site selection of SFT is in high degree of freedom;Protecting natural landscapes in greatest extent;High economic benefit and proper construction costs.These will make SFT play an increasingly role in the construction of connecting structures between the islands and the mainland,the bay crossing channels and the offshore buildings.The Submerged Floating Tunnel is becoming a new research subject in the tunnel profession because of the highly potential application values in the future engineering.The concrete tasks were accomplished in each part as follows:1.This dissertation summarized the loding types in the water environment where the submerged floating tunnel sufferd from,and classified the various loads which effectd on the SFT.2.This part simply introduced the theory of wave,emphatically analyzed the calculating method of the wave force and current force which act on the SFT,and consider the situation which the wave force combined with current force effecting on the SFT,and obtained the current force of SFT with steady flow theory.3.The principle of fluid-structure interaction was introduced in detail,and the theory of the fluid motion equations and turbulence models were also described detailedly,which were used to analysis the nature of fluid motion and get a clear understanding about it.4.By using the finite element software,the simple calculate 2D finite element model of SFT was established.Utilizing the principle of fluid-structure interaction,the ambient environment of the SFT's pipe section were analyzed to find out distribution laws of the flow field and the pressure field in 8 different kinds of pipe section form,then studied and summarized the results carefully.5.The simple calculate 3D finite element model of SFT,by using the finite element software,was established.According to the results of the former analysis,three pipe section forms was chosen to be analyzed about displacement distribution and stress-strain distribution of SFT in changing three key parameters which were ocean current,depth of suspension and type of cross section.Then,the suitable type of section forms could be found by studied and researched these results,at the same time,it would provide a little reference about designing and engineering construction of SFT in the future.