Analysis Of Stability And Towing Motion Characteristics Of Composite Bucket Foundation

Composite bucket foundation is a new type of offshore wind turbine foundation,which can be prefabricated on land,integrated installation,save the offshore operation time,reduce the production,transportation and installation costs.Towing by air flotation is a key technology reflecting the advantages of composite bucket foundation structure.It is necessary to study its stability and towing motion characteristics in depth.In this paper,model test and numerical simulation are the main research methods.A comprehensive and systematic study on stability and towing characteristics of composite bucket foundation is carried out as described next.(1)Model tests were carried out to study the stability law of composite bucket foundations,and the stability law of composite bucket foundations under pitch natural period and eccentric load at different draft depths and ballasts was analyzed.The results were verified with Moses.The calculated results were in good agreement with the experimental data within 10%.(2)Model tests were carried out to study the towing motion characteristics of composite bucket foundation.The effects of draft depth,speed and ballast of composite bucket foundation on the towing force,air pressure and motion characteristics of the foundation were analyzed.Compared with the experimental results by Moses numerical simulation,the results show that the dragging force calculated by Moses is in good agreement with the experimental data,and the corrected air pressure agrees well with the experimental data.(3)The hydrodynamic characteristics is an important manifestation of the wave resistance of composite bucket foundation.In order to study its hydrodynamic characteristics,a basic frequency domain response model with different wave periods and wave direction is established.The hydrodynamic characteristics such as RAO,additional mass coefficient,radiation damping coefficient and exciting force(moment),which compose the hydrodynamic database of composite bucket foundation,related to wave periods are analyzed.(4)In order to predict the motion characteristics of composite bucket foundation in actual sea conditions,a prototype composite bucket foundation model under different wave loads is established,which can provide technical guidance for composite bucket foundation towing.