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.

Fully Coupled Simulation of Interactions Among Waves, Permeable Breakwaters and Seabeds Based on N−S Equations

Interstitial flows in breakwater cores and seabeds are a key consideration in coastal and marine engineering designs and have a direct impact on their structural safety.In this paper,a unified fully coupled model for wave−permeable breakwater−porous seabed interactions is built based on an improved N−S equation.A numerical wave flume is constructed,and numerical studies are carried out by applying the finite difference method.In combination with a physical model test,the accuracy of the numerical simulation results is verified by comparing the calculated and measured values of wave height at measurement points and the seepage pressure within the breakwater and seabed.On this basis,the characteristics of the surrounding wave field and the internal flow field of the pore structure,as well as the evolution process of the fluctuating pore water pressure inside the breakwater and seabed,are further analyzed.The spatial distribution of the maximum fluctuating pore water pressure in the breakwater is compared between two cases by considering whether the seabed is permeable,and then the effect of seabed permeability on the dynamic pore water pressure in the breakwater is clarified.This study attempts to provide a reference for breakwater design and the protection of nearby seabeds.

Wave-current-induced soil response in marine sediments

This letter presents a new analytical approximation for wave （current）-induced dynamic soil response in marine sediments. In the model, the third-order approximation for wave-current interactions is employed for the flow model, while Biot＇s dynamic poro-elastic model is used to simulate the porous flow in a seabed. The newly analytical solution is validated with the field observations. Based on the solution, effects of currents and wave-nonlinearity on soil response are examined and a parametric study will be carried out to examine the influence of currents on the liquefaction potential. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi： 10.1063/2.1301202]