Response of a porous seabed to water waves over permeable submerged breakwaters with Bragg reflection

An integrated model is developed for the investigation of wave motion and seabed response around multiple permeable submerged breakwaters subject to different levels of Bragg reflection. In this study, the Volume-Averaged Reynolds-Averaged NavierStokes (VARANS) equations are used to describe the non-linear interaction between waves and permeable structures, while Biots u-p approximation theory is adopted for predicting the wave-induced seabed response. The numerical results show that the reflection coefficient is highly dependent on the wave period and the configuration/number of arrayed breakwaters. Wave motion and its induced seabed response (in terms of pore fluid pressure, vertical effective stress and liquefaction potential) around breakwaters can be largely changed due to Bragg reflection and energy dissipation of permeable structures. With the same incident wave conditions, the maximum liquefaction area decreases in size with an increasing soil permeability or degree of saturation.