Hydrodynamic investigation on the submerged tunnel suspended from a fixed platform using SPH method

In this paper, the coupled dynamic motion characteristics of a tunnel element suspended from a platform have been studied at a 1:50 scaled model by using the weakly compressible Smoothed Particle Hydrodynamic (WCSPH) method. The corresponding numerical model was validated with the experimental published data of the motion characteristics of the tunnel suspended from a fixed platform, and the case of a floating structure with its mooring lines. Multiple linear wave conditions and different sinking depths of the submerged were involved in the numerical model for tunnel dynamic response and cable behavior investigation. Effects of the mooring system, the wave parameters, the tunnel sinking depth and its mooring configurations were studied. The numerical results were arranged to inform about the dynamic characteristics and mooring behavior for different case studies. The results indicate that the tunnel motions decrease with the increment of the tunnel sinking depth and decrease with the decreasing mooring angle. The natural periods of the tunnel-platform system play key roles in the wave condition impacts on the tunnel motions. It was found that the additional mooring system anchoring the tunnel to seabed played a specific role in reducing the tunnel motions in roll and sway, the motion amplitude of the tunnel in heave is mainly controlled by the suspension cables, particularly when subjected to lower sinking depth and longer period waves.