Shaking table tests of offshore wind turbine systems with a suction bucket foundation in sandy seabed subject to earthquake and wind loads

With the rapid development of offshore wind power industries in China, a significant proportion of existing and planned offshore wind farms are located near seismically active zones with liquefaction potential. Seismic liquefaction threaten the safety of suction bucket foundations supported offshore wind turbines. The shaking table tests for sandy seabed - suction bucket - offshore wind turbine system were carried out under combined wind and earthquake loads. The response of the ground and structure under seismic and wind loads was investigated carefully. The effects of wind load, seismic load, and drainage holes in the top cover of the suction bucket on the dynamic response of this system were obtained. Test results indicate that the increase of peak acceleration results in the increase of seabed, turbine response, excess pore water pressure and wind turbine's rotation. The influence of 2 Hz sine wave on offshore wind turbines is greater than that of 4 Hz. The tilt of the wind turbine under the combined action of wind and earthquake is greater than that under the action of wind load or earthquake alone. Top drainage of the bucket foundation will reduce the seismic capacity of the suction bucket foundation. The research can provide reference for the seismic design of suction buckets for offshore wind turbines.