Abstract: Jiangsu offshore belongs to the South Yellow Sea, which is the most concentrated area of offshore wind farms in China. At present, it accounts for about 70%?75% of the total installed capacity of China. The overburden layer thickness in this area is very large, soils along the pile length depth (generally 40?60 m) are mainly silty sand, silt and silty clay, especially the easily liquefied silty sand silt layer at the depth of 20 m below the mud surface. The South Yellow Sea is also an earthquake activity area in China. Therefore, the seismic liquefaction characteristics of the horizontal site of offshore wind farm in this area are studied. Firstly, based on the statistical characteristics of drilling data of 50 sites in an offshore wind farm in the South Yellow Sea, the generalized formation model is established. The soil dynamic parameters are calibrated based on dynamic triaxial test and resonance column test, and three ground motions are inversed (EL-Centro, Northridge and Kobe), and the peak ground acceleration (PGA) near the surface is adjusted to 0.05g, 0.10g, 0.20g and 0.40g respectively, and the site liquefaction is researched. The characteristics of excess pore pressure ratio, total settlement and layered settlement under earthquakes are analyzed. It is found that the strata in this area are liquefiable soils, the excess pore pressure ratio of each layer is less than 1.0 when input PGA is 0.05g, and the total settlement is about 1 cm. When input PGA is 0.10g and 0.20g, only the surface layer (within 12 m) is completely liquefied, and the total settlement is 10 and 17 cm respectively. When input PGA is 0.40g, the 20 m strata below the mud surface are completely liquefied, and the total settlement is about 30 cm. Under different earthquakes, the settlement of surface soil (12 m) accounts for the largest proportion (more than 95% when PGA is 0.10g and 0.20g). Therefore, the liquefaction characteristics of offshore wind farm under earthquakes should be considered for turbine pile foundation.

Key words: offshore wind turbine, South Yellow Sea, earthquake, liquefaction analysis, ground settlement