Research Of Steel-concrete Composite Bucket Foundation Structures For Offshore Wind Turbine

Maritime wind energy is an abundant, clean and renewable energy, but the Infrastructure for offshore wind turbine in which the environment is so complex that it is difficult to transport construction, and the construction cost high; in addition, how to ensure the stability and security of the offshore wind turbine infrastructure under complex loads is a hot project today. As a new-style platform foundation, bucket foundation is widely used in various marine structures facilities for the reasons that it has so many merit such as simple structure, flexible, reliable and reusable. In this paper, a new-style offshore bucket foundation was designed, and its feasibility was studied through theoretical analysis and numerical simulation. Focusing on the following issues:(1) According to the fan site choiced, the specific farms external conditions are determined. Various loads will focus on the bucket foundation during use. The loads were analyzed and the corresponding theoretical calculating methods of these loads are gived in the paper to determine work condition. Analysed the characteristics of bucket foundation and working mechanism to explain the theoretical calculating methods of bucket foundation's load-bearing characteristics. The theoretical analysis of the static stability of air float bucket foundation was introduced. Whether an air float structure is in stability can be judged by the parameter of stabilizing height. Several factors that effects suction penetration of bucket foundation were introduced, and the theoretically calculating formula of underpressure was provided. Allowable value of negative pressure changed with the inserting depth of bucket foundation. The transformation was obtained to used to guide the underpressure-control during construction period.(2) According to the basic design elements, Steel structure and Steel-concrete Composite Fucket Foundation are designed. And coMPared two programs from basic weight, cost, stability, the towing floating and suction penetration during construction, and then the steel-concrete combination program was chosen as the best one.(3) The bucket foundation that designed were numerically calculated and analyzed in ABAQUS. Checked the displacement and stress under normal operating conditions and extreme conditions, and specifically analysed the influence that acted on the bucket foundation by soil. The bucket foundation's load-bearing characteristics under monodirectional loads were numerically calculated using displacement control method, then lay the foundation of the numerical calculation of the bucket foundation's load-bearing characteristics under combined loading.(4) Evaluated the fatigue life of steel structures in the method of finite element analysis using the appropriate fatigue SN curves, to provide evidence-based theories for the design of foundation.