Influence of soil parameters on the seismic response of offshore wind turbines in liquefiable soils

The goal of this study is to investigate the effect of model parameters on the behaviour of offshore wind turbines in liquefiable soils under earthquake loading. Numerical analyses were conducted using an advanced soil constitutive model for liquefaction behaviour, the P2PSand model, available in FLAC3D. A previous study was chosen from the literature to verify the created numerical model, comparing pore water pressure in the soil and horizontal displacement of the monopile. The results indicate that the model can accurately predict both soil and pile behaviour. After validation, a new model was created to assess the effect of liquefiable soil parameters. Three soils were selected for comparison: Ottawa sand, Karlsruhe fine sand, and standard cyclic resistance field (SCRF) sand. Calibration of the model parameters for these soils is well-documented in the literature. A single earthquake record was applied to the model base, and the responses of free-field ground acceleration at the surface, superstructure (tower) acceleration, and pile head rotation were compared. Results showed that offshore wind turbine response in liquefiable soils is strongly influenced by soil parameters. Particularly, the parameters of SCRF sand led to higher ground and tower accelerations, resulting in greater monopile head rotations.