Effects of bottom shear stresses on the wave-induced dynamic response in a porous seabed: PORO-WSSI (shear) model

When ocean waves propagate over the sea floor, dynamic wave pressures and bottom shear stresses exert on the surface of seabed. The bottom shear stresses provide a horizontal loading in the wave-seabed interaction system, while dynamic wave pressures provide a vertical loading in the system. However, the bottom shear stresses have been ignored in most previous studies in the past. In this study, the effects of the bottom shear stresses on the dynamic response in a seabed of finite thickness under wave loading will be examined, based on Biot's dynamic poro-elastic theory. In the model, an "u-p" approximation will be adopted instead of quasi-static model that have been used in most previous studies. Numerical results indicate that the bottom shear stresses has certain influences on the wave-induced seabed dynamic response. Furthermore, wave and soil characteristics have considerable influences on the relative difference of seabed response between the previous model (without shear stresses) and the present model (with shear stresses). As shown in the parametric study, the relative differences between two models could up to 10% of p0, depending on the amplitude of bottom shear stresses.