Research On Model Selection And Numerical Simulation Of Key Parameters Of Tension Legs In Submerged Floating Tunnel

Submerged Floating Tunnel(SFT)in English is a new form of underwater traffic.With the rapid development of society today,traditional cross-water traffic modes such as subsea tunnels,immersed tunnels and cross-sea bridges Although it has been used for a long time,in some special cases,such as over long distances crossing waters,when the seabed terrain is undulating and the geological conditions are not suitable for use,a new path is needed.SFT is a new type proposed based on this consideration.The new transportation structure has become a hotspot of research in various countries.In addition to the need for special research on the upper pipe type and joints of the suspended tunnel,its supporting type is also of great significance to the success of the project.In this paper,based on the investigation of relevant literature of submerged tunnel tension legs,a numerical analysis method is used to comprehensively consider the selection of tension leg layout and several key parameters to study the mechanical response of tension legs under different working conditions.The main research work of the thesis includes the following aspects.(1)Briefly introduces three typical structural layout forms of tension legs: A,W,M,sorts out the types of loads that the submerged tunnel is exposed to under the marine environment,introduces the calculation theory and formulas related to the ocean current force and wave force of the tunnel structure,which are numerical values The simulation calculation provides the corresponding theoretical basis.(2)Considering the main calculation parameters such as tension leg arrangement form,number of tension legs n,anchor cable arrangement angle θ(angle with vertical direction)and ocean current velocity v,the numerical calculation conditions were determined according to the orthogonal combination method,and the numerical simulation software ABAQUS was used Carry out simulation calculations to obtain the static response of single-section independent submerged tunnel structure and tension leg anchor cable under the action of steady ocean current.The stress and tension of the tension leg and the displacement and deformation of the tunnel tube are used as evaluation indicators to study the reasonable tension leg configuration and parameters.(3)Considering that ocean current load may excite the submerged tunnel structure and cause resonance effects,on the existing tension leg layout schemes,dynamic analysis and calculations are carried out for the three layout types at 20° and 30°inclination structures,and the submerged tunnel is compared and analyzed Multiple vibration modes and their natural frequencies;and analyzes the dynamic loading effect of the tube at different inclination and different flow rates,and conducts in-depth research on the layout and related parameters of the tension leg.The ideal layout scheme of the tension leg support system and the recommended values of key layout parameters derived from the research in this paper have certain reference value for the construction design that may be implemented in the future.