Evaluation of wave force acting on Submerged Floating Tunnels

The purpose of this study is to investigate the wave force characteristics acting on the Submerged Floating Tunnel (SFT). When the wave force acting on a large size structure is estimated such as ships and floating platforms, the diffraction theory based on the velocity potential is often used because the inertial force is dominant for the wave force evaluation. If the structural size is rather small and the drag term cannot be neglected, on the other hand, the empirical equation known as Morison’s equation is widely used. SFT is a completely submerged structure and the size of that may differ from a small one for pipeline to a large one for highway or railroad system. It is obvious that an appropriate evaluation of wave force is essential for predicting the dynamic response due to wave. In this study, the wave force was evaluated based on the diffraction theory by Boundary Element Method first, and the effects of the size and the shape of SFT on the wave force are discussed. Second, the Morison’s equation which can estimate both drag and inertial forces was applied to evaluate the role of drag force. Those results were compared with experimental results and the findings through those studies are introduced.