Study On Deep Water Sinking Behavior Of Offshore Wind Turbine Bucket Foundation Machine Under Wave Action

With the rapid development of offshore wind power,the forms of wind power infrastructure continue to innovate.Bucket foundation,as a new type of offshore wind power infrastructure,can achieve self-floating towing,negative pressure sinking and other advantages with good load carrying capacity,and can be rapidly promoted and applied in the field of offshore wind power.The installation of the bucket foundation machine is an efficient and economical set of offshore wind power development technology,which mainly includes onshore prefabrication,air-floating towing,water sinking,and soil sinking and other processes.Among them,the water sinking process of the bucket foundation machine is complex,and its difficulty will be significantly increased as increases of the water depth.At present,the applied water depth of bucket foundation is within 15 m.In recent years,due to the large-scale development and utilization of offshore wind energy resources,the offshore wind potential must face the development of deeper sea areas.Therefore,in order to meet the actual engineering needs and continuously improve the water sinking technology of the bucket foundation machine,this paper studies the behavior of deep water sinking the bucket foundation machine under the action of waves by using model tests and numerical simulations for30 m water depth,and the results are as follows:(1)Through the model test,the dynamic and kinematics characteristics of the bucket foundation machine under different wave heights and periods were analyzed.At each sinking stage,the sling force,pitch angle,acceleration at the fan head of the bucket foundation machine were positively related to the wave height,and increased with the increase of the period;under the same conditions,the acceleration in the X direction at the fan head was larger than Z direction acceleration.(2)Through model tests and numerical simulations,the dynamic and kinematic characteristics of the bucket foundation machine at different sinking depths were compared and analyzed.The conclusion was that the dangerous stage of the deep water sinking process of the bucket foundation machine was that the water surface just exceeded the bucket foundation cover.At this stage,the sling force,the pitch angle,and the acceleration at the fan head all increased,and basically reached the maximum value of the entire sinking process.At the same time,when the wave height exceeds 1.5m,the acceleration in the X direction exceeds the maximum allowable acceleration of the fan head by 0.20 g,and the pitch angle was within 2°.(3)Three arrangement forms with different number of slings were proposed and analyzed through numerical simulation in this paper,including three,four and five slings.In the stage of dangerous sinking,kinematics characteristics of the bucket foundation machine under the three types of arrangement forms were compared and analyzed.Under three types of sling arrangement,the tendency of the pitch angle and the acceleration in the X-direction at the fan head was basically the same as the sinking depth increased,all showing a trend of increasing first and then decreasing.At the same sinking depth,the pitch angle and the acceleration in the X direction at the fan head of the 4 slings arrangements were greater than the pitch angle and acceleration of the 3and 5 slings arrangements.The difference between the pitch angles and the X direction at the fan head of the 3 and 5 slings arrangements was small.From the perspective of safety and economy,the 3 slings arrangement was more suitable.