Research On Bucket Foundation With Large-capacity Of Offshore Wind Power In Deep Water

Offshore wind power has the advantages of high wind speed,being close to the load center and not occupying land resources.At present,the development trend of offshore wind power is to increase the capacity of single wind turbine and move from offshore to deep sea.The fixed foundation of offshore wind power has been greatly developed in recent years,but it is still mainly concentrared in offshore shallow water.Applicable to the offshore wind power foundation and supporting construction technology in the deep water(30m to 50 m water depth),and adapt to the development trend of largecapacity units,becoming the only way for the development of wind power.Compared with the fixed foundation in shallow offshore waters,the fixed foundation in deep offshore waters faces more complex sea conditions and larger size.Compared with the shallow water area,the loads such as waves and currents in the deep offshore waters area have a greater impact on the foundation,resulting in poor safety and stability of the fixed foundation in deep waters,and difficult design and construction,and high cost.How to make the foundation run safely and reliably in deep waters,while controlling the cost and construction difficulty,has become the research purpose of this thesis.To solve the above problems,the new bucket foundation—composite single bucket foundation is proposed in this paper,and research on the design,static and dynamic aspects of the new bucket foundation are carried out,and verified its feasibility from the perspective of force.Specifically,it includes the following aspects:(1)Research on basic structure and design method of composite single bucket foundation.The basic composition and structure of a new type of offshore wind power foundation structure with bucket foundation,which is developed for deep-water largecapacity units are introduced,and the basic situation of the external forces acting on the foundation structure is analyzed.Through the methods of structural mechanics and soil mechanics and referring to relevant design codes and regulations,the design method of composite single bucket foundation is prosed.Based on the above design method,the basic structure design of a sea area wind power project was carried out.(2)Optimization of composite single bucket foundation.Combining the deep sea environment and geological conditions of actual engineering,aiming at structural safety,stability,applicability and economy.The finite element static calculation is carried out for different structural shapes by using ABAQUS finite element software,the stress state,displacement state and structural stability performance of different structural shapes are analyzed.Finally,the suitable deep-sea large capacity offshore wind turbine foundation is obtained by optimizing different structural parts.(3)Dynamic characteristics and fatigue analysis of composite single bucket foundation.Analyze the dynamic characteristics of the new bucket foundation offshore wind power foundation.The finite element models of the basement and foundation,tower tube and superstructure are established,the self-vibration characteristics of the structure are analyzed,and the resonance of the structure is checked.Considering the coupling effect of wind,wave,current and load,the dynamic calculation of offshore wind turbine is carried out,the force mechanism and working state of the fan are analyzed.The dynamic response characteristics and the structural dynamic safety were evaluated.The fatigue analysis of the steel structure joints was carried out by the hot spot stress method,and the structural fatigue strength and service life were systematically evaluated.