Structural Response Of Submerged Floating Tunnel Section Under The Action Of Wave-Flow Coupling

In recent years,with the development of science and society,the scope of human activities is more and more extensive,and people’s demand for transportation is also growing.The construction of underwater tunnels is also gradually developing from flat rivers to gullied bays and straits.The traditional construction methods of underwater tunnels are facing great challenges.As an optimal cross sea traffic structure,Submerged Floating Tunnel(SFT)has great potential in application.This article is supported by the Ministry of Transport’s scientific and technological project “Preliminary study on Key Technologies of deep-sea Submerged Floating Tunnel”,the structural dynamic response of SFT pipe section is studied,and the model test and numerical simulation are compared,and the following conclusions and results are preliminarily obtained:1)An overview of the loads on SFT in water,and a summary of their classification.Various wave theories are introduced in detail,and their application scope is analyzed to some extent;the effects of water flow on SFT are analyzed and the calculation theory is determined.2)Numerical simulation.At different wave heights,as the wave height increases,the extreme value of the flow field pressure and the displacement of the tube section increase with the continuous increase of the wave height,and with the increase of the wave height,the wave pressure on the tube section and the The effect of displacement gradually increases;the maximum stress point of the SFT pipe section under the same conditions mainly occurs at the junction of the pipe section and the anchor cable;at different water flow rates,the displacement extreme value of the SFT pipe section gradually increases with the increase of the water flow rate,and The displacement is linearly correlated with the change of water flow velocity.When the water depth is set in different pipe sections,the displacement extreme value of the SFT pipe section gradually decreases with the increase of the water depth of the pipe section.When the water depth of the pipe section is greater than 25 m,the displacement extreme value is larger.The decrease of the amplitude,that is,the displacement of the SFT pipe section becomes less and less affected by the wave height as the pipe section depth increases.3)Model test.Under the action of pure flow.The pressure of the SFT pipe section increases with the increase of the water flow velocity,but from the pressure distribution on the pipe section,it can be seen that the flow velocity has little effect on the pipe section pressure.The pipe section pressure is mainly controlled by the set water depth of the pipe section;under pure wave.The pressure at the measuring point of the frontal wave surface increases with the increase of the wave height,and the extreme value difference of the frontal surface pressure of the pipe section increases with the increase of the wave period,but as the water depth of the pipe section is continuously deepened,the pressure of the wave on the frontal surface of the pipe section The effect of γgradually decreases;the maximum value of six degrees of freedom increases with the increase of wave height,but with the increase of water depth,the maximum value of six degrees of freedom decreases continuously;under the effect of wave-current coupling.The pressure at the measuring point of the frontal wave surface increases with the increase of the wave height.The larger the flow velocity of the wave,the smaller the pressure of the frontal wave surface.As the water depth increases,the maximum value of the six degrees of freedom decreases continuously,and as the flow velocity increases,the displacement of the pipe section tends to increase.4)Through the research on the response of the SFT structure under the coupling of wave and current in the model test,the fitting obtained the regression function of the reasonable setting of the water depth of the SFT section with the maximum pressure difference of the section and the maximum displacement of the section And from this calculation,the minimum set water depth of the pipe section model under different allowable pressure extreme value differences and different displacement maximum control indexes is obtained.5)On the whole,the research results of the structural response of the SFT section under the wave coupling show that the numerical simulation and model test under other conditions are certain,the pressure and displacement of the pipe section increase with the increase of the wave height Large;the displacement of the pipe section increases with the increase of the water flow velocity,and decreases with the deepening of the water depth set in the pipe section,and the movement of the pipe section displacement in the lateral direction is more significant.In general,numerical simulation and model tests show the same change law.