Cross-flow and torsion coupled dynamic response of submerged floating tunnel under the action of ocean current

Submerged floating tunnel (SFT) is a kind of long distance flexible sea structure. The dynamic behavior of SFT is bound to be affected by the action of ocean current. According to the typical cross-section of the structure, the two-dimensional plane coupled vibration equations are derived based on Lagrange equations to analyze the cross-flow and torsion coupled dynamic response of SFT in ocean current environment. Meantime, the fourth-order Runge-Kutta method is used to solve the vibration equations. Finally, the effect of some key parameters, such as the height-width ratio, eccentric throw and the current velocity are investigated. The results show that the eccentric throw and the current velocity have obvious effects on the coupled structure vibration. With the increase of the eccentric throw and current velocity, the amplitude of the coupled vibration increases. Moreover, it can guarantee the relatively small vibration amplitude in cross-flow direction and torsion, when the height-width ratio is between 0.5 and 0.6.