Study On Dynamic Response Of Seabed Under Waves Based On DEM-PFV Coupling Method

The stability of nearshore/offshore structures will be affected by wave loads.The deformation,softening and liquefaction of the seabed under the action of cyclic wave will result in loss of the self-bearing capacity,which endangers the safety of the structure.Based on the open-sourced discretization method software Yade,DEM-PFV coupled model is established by coupling discrete element method(DEM)and porescale finite volume method(PFV),and the simulation of wave action in the model is improved.By loading the wave pressure on the surface of the seabed,the liquefaction of the seabed with different soil properties under the action of regular wave and irregular wave is simulated.The main conclusions and achievements of the study are as follows:(1)A DEM-PFV model was established by using the discrete element method(DEM)in the solid phase and coupled with PFV in the liquid phase based on the opensource DEM software Yade.The dynamic response of porous seabed under wave is analyzed.(2)The established numerical model is verified by comparison with the experimental data,analytical data and numerical results.Sensitivity analysis of selected representative particle size in the model shows that properly increasing the particle size(less than 1/6 of the minimum dimension of the model)will take no effect on the simulation results.Furthermore,the decrease of the number of particles will effectively improve the computational efficiency.(3)Under the action of regular wave,the influences of the porosity and elastic modulus of seabed on pore-pressure and liquefaction of seabed are considered,and the dynamic changes of seabed soils are analyzed,such as porosity and total kinetic energy of particles and so on.The results show that the liquefaction resistance of sandy seabed soils under regular wave can be effectively enhanced by decreasing the porosity and increasing the elastic modulus.The processes of consolidation,compaction and liquefaction on the seabed under wave actions are explored.(4)The pore-water pressure changes and liquefaction of seabed with different porosities and elastic modulus are analyzed under the action of irregular waves,and the dynamic responses of seabed soils are analyzed.It is consistent with the results of regular wave that the liquefaction resistance of sandy seabed can be effectively enhanced by decreasing the porosity and increasing the elastic modulus.And compared with the regular wave,the irregular wave has a greater influence on the stability of the seabed soils due to the appearance of wave pressure large value.