Study And Application Of Integrated Numerical Model For Wave-Seabed-Structure Interaction

In order to exploit marine resources,a large number of marine structures have been built on the offshore coast in recent years.Seabed structures will be impacted by environmental loads such as extreme waves and typhoons during the service period.Whether marine structures can withstand the test of these environmental loads is an engineering problem worth studying.It is worthy to study whether if the marine structures can sustain the impact of these environmental loads.Based on this,the paper established a one-way integrated numerical model for wave-seabed-structure,then the numerical model is applied to study the dynamic response characteristics of the second breakwater in the West Port of Yantai Port and the single pile(full diameter)offshore wind turbines and offshore launching platform under wave loads.The main results are as follows:1.In this study,a one-way integrated numerical model for wave-seabed-structure interaction is established through the integrated wave model(Ola Flow)and the soil dynamic response model(ABAQUS).In this new model,the generation and the propagation of ocean waves as well as the seepage flow in the porous medium are controlled by Ola Flow;meanwhile,the wave-induced dynamic response of porous seabed and marine structures is governed by ABAQUS.The numerical model established in this paper has been extensively validated using analytical solutions and wave flume experiments.The conformity of the numerical results and the experimental results indicates that the established integrated model is rather reliable.2.To establish a simplified model,the soil dynamic response sub-model in the numerical model was simplified,and the Contact Friction Theory was substituted into the numerical model.The simplified model is used to study the sliding of structures under wave loads,which further expands the functions of the wave-seabed-structure integrated numerical model.Taking the composite breakwater tank test as a typical case,the simplified model is used to study the residual horizontal displacement of the caisson under the impact of wave forces.3.The established wave-seabed-structure integrated numerical model is used to study the stability of the second breakwater and its seabed foundation in the West Port of Yantai Port under the most extreme wave loads in 50 years.The result shows that the breakwater can still be functional under extreme wave conditions:(1)The breakwater caisson is able to resist the impact of wave force,the maximum shaking amplitude of the top of the caisson is about 4cm.(2)The breakwater has sufficient capacity to resist wave overflow,and the average overflow of the breakwater is about 6L/(s?m).It is concluded that the second breakwater in the West Port of Yantai Pors till maintained a strong service capacity under the most extreme wave conditions in 50 years.4.The numerical model is further extended to a three-dimensional form,and the wind load is embedded in the established numerical model.The numerical model is used to study the dynamic response of the offshore wind turbine and its seabed foundation under extreme wave and wind loads.It is concluded that: Under the action of extreme wind and wave loads,residual horizontal displacement of the top of the wind turbine reaches 0.4m,the the maximum inclination angle of the wind turbine is about 0.8°,and the transient liquefaction zones appear in the seabed around the wind turbine and.Since the maximum inclination of the wind turbine is less than 10°,the wind turbine can still be considered functional.The established wave-seabed-structure integrated numerical model is further applied to study the stability of the offshore launching platform and its seabed foundation under ordinary wave loads.It is concluded that: The maximum shaking amplitude of the top of the platform is about 4cm,and there is no obvious residual displacement.It indicates that the offshore launching platform is stable under ordinary wave loads.