Dynamic Response of an Offshore Pile, a Poro-Elastic Seabed and Seawater due to Water Waves

Abstract

In this study, a coupled model is developed to address the dynamic response of an offshore pile to linear water waves. In the coupled model, the pile and the seabed are treated as a saturated poro-elastic medium described by Biot’s dynamic theory, while the seawater is considered as a conventional acoustic medium. To establish the coupled model, boundary element formulations for saturated porous media are derived for the pile and the seabed, respectively, and the acoustic boundary element formulation is constructed for the seawater. The coupled boundary element model is obtained using these three boundary element formulations as well as the continuity conditions along the interfaces between the pile, the seabed and the seawater. In the model, linear water waves are considered as an external load and its load is evaluated via the wave function expansion method. Numerical results shows that increment of the modulus ratio between the pile and the seabed can reduce the horizontal displacement of the pile and the pore pressure of the seabed around the pile. Also, the maximum pore pressure of the seabed usually occurs at the upper part of the seabed around the pile.