Fundamental study on the parametric excitation characteristics of Submerged Floating Tunnel

This paper deals with the characteristics of the parametric excitation, which is one of the dynamic instability phenomena, of Submerged Floating Tunnel. In this study, it is assumed that the structure is moored by some tension legs and located in the water between seabed and water surface. The parametric excitation is caused by the time tension force of tension legs. The time-varying tension force arises when some dynamic loads such as regular waves act on the floating body and the body moves in the water. The analytical studies are carried out to confirm the possibility of the occurrnce of unstable motions by introducing Mathieu-type equations in this study and effects of tension leg arrangements, viscous damping, quadratic damping and external forces on the parametric excitation characteristics are investigated in particular.