The Dynamic Response And Corrosion Fatigue Research Of The Tethers Of The Submerged Floating Tunnel

With the continuous development of economy and the deepening of communication,how to quickly and safely cross the rivers,lakes and seas has become more and more concerned.At present,the bridge is still the main form of the span structure,but because of its high demand for the terrain on both sides of the river,the bridge cannot be implemented in some steep places.Immersed tube tunnel is another kind of span structure.Although it has low requirements on both sides of the Strait,the tunnel is embedded in the sea floor,so it has high requirements for water depth and seabed soil quality.And it does not have extensive practicability.As a new type of traffic structure,submerged floating tunnel has attracted more and more experts' attention because of its good economy and applicability.Due to the complexity and uncertainty of underwater environment,the stability and safety of submerged floating tunnel are the problems that need to be solved urgently.On the basis of consulting a large number of domestic and foreign literatures,the parameter response,corrosion fatigue and other aspects of the anchorage structurecable are analyzed in this paper.The main contents are as follows:(1)Making comparative analysis of the submerged floating tunnel in different forms and different cable layout.Combined with the actual sea state of Qiongzhou Strait,the anchor type with inclined cable of submerged floating tunnel is finally chosen.(2)The vibratory response of cable is simulated and analyzed.Under the same condition of the parameter excitation,when the flow velocity is 4m/s,the vibration amplitude of the cable reaches the maximum value;at the same flow rate,when the parametric excitation frequency is 2 times of the natural frequency of the cable,the vibration response amplitude of the cable is the largest.(3)By using the method of Palmgren-Miner linear cumulative damage and S-N curve to assess the life of cable,with structural dynamic equations combined with tunnel-cable coupling model,the stress amplitude of cable is calculated.Fatigue corrosion life of cable is evaluated by the model of multi stage fatigue corrosion.The calculation results show that when the cable begins to corrosion,it will start to fatigue in a very short time,which will greatly shorten the fatigue life of cable.(4)The main mechanical properties of the new material CFRP(Carbon Fiber Reinforced Polymer)and its application in the field of submerged floating tunnels are discussed,and the vibration of CFRP cable and steel cable is compared combined with the vibration equation of cable.Without considering the damping,steel cable has more excellent performance on vibration amplitude and vibration frequency,after considering the damping,the vibration amplitude of CFRP cable decreases rapidly,lower than the cable,but the vibration frequency is higher than that of steel cables.