The impacts of internal solitary waves on a submerged floating tunnel

Abstract

The interaction between an oceanic internal solitary wave (ISW) and a prototype submerged floating tunnel (SFT) is numerically investigated. Effect of oceanic internal solitary wave amplitude, the relative distance of the SFT to the pycnocline, cross-sectional geometry of the SFT, and the density ratio of the two fluid layers are analyzed. At a potential application site, the dynamic response of an SFT composed of a tube-joint-mooring system forced by an oceanic ISW is studied using Finite Element Method (FEM) modeling. The numerical results show that the ISW-induced force can be effectively reduced by adopting a parametric SFT cross section instead of a circle or ellipse. The influence of the relative distance of the SFT to the ISW pycnocline is crucial, and can remarkably alter the vertical force and buoyancy-weight ratio (BWR) of the SFT during ISW propagation. Large shear forces and bending moments on the SFT can occur, affecting the tension in the mooring lines, and threatening the safety and reliability of the SFT system. However, the deflections and accelerations of the SFT under the applied ISW are within structural serviceability requirements due to the low frequency of the ISW compared to the natural frequency of the SFT tube.