Research on Three-Dimensional Response Analysis of Submerged Floating Tunnel Cable Under Parameter-Vortex Excitation

In order to investigate the multi-directional coupled motion of the mooring cable under multi-degree-of-freedom parametric excitation, a three-dimensional coupled motion analysis model was established based on Hamilton’s principle and the Kirchhoff assumption. The analytical result was compared with the classical theoretical model of cable to verify the accuracy and reliability of the new model. The ocean current load was simplified as a uniform flow, and the motion of the upper endpoint of the cable was approximated as the motion of the tunnel body. Then, both axial and in-line parametric excitations were taken into account, and the fourth order Runge-Kutta method was employed for the solution. Lastly, the dynamic response characteristics of the cable structure in the axial, in-line and cross-flow directions were analyzed. The results show that a coupling phenomenon of mutual promotion or suppression exists between the two types of parametric excitations in both in-line and cross-flow displacement responses. Under most working conditions, compared with the single–degree-of-freedom parametric-vortex excitation, the axial and in-line parametric excitations further increase the displacement responses of the cable structure in all directions.