Experimental and numerical research on the wet-towing of wide-shallow bucket jacket foundation for offshore substation

Abstract

Offshore wind power is a kind of clean and renewable energy. In recent years, offshore wind power has been exploited more and more widely. With the hub of power collection of offshore wind farm, the offshore substation becomes an important facility for offshore wind power transmission and transformation. In this paper, the current situation of the foundation and installation mode of offshore wind farm substation are introduced, with emphasis on an integral wet-towing method based on a wide-shallow bucket jacket foundation (WSBJF). Firstly, based on the advantages of the integral installation mode of offshore wind power and the composite bucket foundation, the WSBJF of offshore substation is proposed. Secondly, the wet-towing method and the corresponding construction processes of WSBJF are elaborated, and the feasibility of the wet-towing method is verified by the indoor model experiments and numerical simulation analysis. Finally, with the help of the model experiments and numerical simulation, the effects of draft depth, wave height and wave period on foundation stability and dynamic response are investigated. The results show that it is feasible to carry out long distance wet-towing of the foundation under the condition of level 5 wind and waves. WSBJF has a certain self-floating ability, which can meet the wet-towing stability requirements without upper platform. Reducing draft depth and increasing wave height will reduce the stability of WSBJF during wet-towing. Under the premise of a certain draft depth of the foundation, when the wave period is close to the natural period of the WSBJF, the WSBJF will be rocked greatly. For example, the pitch angle of the WSBJF at 14 s wave period is 56 times that at 6 s wave period.