Study On The Influence Of Sand Seabed Characteristics On Wave Load Of Single Pile

With the continuous development of offshore engineering,a large number of offshore structures have been constructed in the offshore area.For marine structures,it is inevitable to suffer from a variety of complex marine dynamic loads.In the process of interaction between wave and structure,wave load is often the control load of structure design.However,in the past studies,the seabed was regarded as a rigid and impermeable solid,and the effect of sandy seabed on wave energy dissipation was ignored.Therefore,in this paper,according to different wave conditions(wave height,period,water depth)and seabed characteristics(porosity,particle diameter,seabed thickness),the influence of wave load on single pile is studied,so as to analyze the dissipation mechanism of sand seabed soil on wave energy,and then reveal the influence of wave parameters and seabed characteristics on wave load on single pile in sand seabed.In this paper,the effect of sandy seabed characteristics on wave load on single pile is studied by combining physical model test with numerical simulation.Due to the limitation of test conditions,it is not possible to analyze each influencing parameter one by one.Considering the characteristics of sandy seabed,N-S equation,standard k-?turbulence model and nonlinear Forchheimer equation are adopted to describe the pore flow in sandy seabed.A three-dimensional numerical model of wave-seabed-single pile interaction is established to study the influence law of each parameter on wave load on a single pile.(1)The interaction between waves and structures is simulated by flume test.Five different seabed soils are changed and the same thickness is fixed.The variation law of wave load on single pile under different porosity and particle diameter conditions is studied.The test found that the existence of seabed characteristics has certain influence on the wave load on a single pile.The rationality and accuracy of the model are verified by comparing the newly-built numerical model with flume test data.(2)Based on the new numerical model,by changing the wave height,period,water depth,other conditions are consistent,the influence of different single wave conditions on the wave load of single pile is analyzed.Based on the analysis of the curve of wave force variation with wave parameters and the curve of wave force time history of single pile,it is found that with the increase of wave height and period,the wave load of single pile increases gradually,and the wave forms of wave height and period time history curve are sharp and compact;with the increase of water depth,the wave load of single pile decreases gradually,and the time history The waveform of the curve is very regular and smooth.(3)By changing the porosity,particle diameter and seabed thickness,the wave load curve of single pile with the characteristics of sandy seabed and the maximum wave force curve of single pile with the characteristics of sandy seabed are studied.It is found that the effect of porosity on the wave load of single pile is very obvious,which increases first,then decreases,and then increases.When porosity = 0.8,the wave force of single pile is the smallest;with the increase of particle diameter and seabed thickness,the wave load of single pile decreases gradually.In the study of the influence of the sand seabed particle diameter on the wave load on a single pile,the wave force on a single pile is fitted by a formula,and the fitting results are more suitable to the numerical simulation results.