The effect of pile-soil interaction on structural dynamics is investigated for a large offshore wind turbine in the hurricane-prone Western Gulf of Mexico (GOM) shallow water. The offshore wind turbine has a rotor with three 100-meter blades and a mono-tower structure. Loads on the turbine rotor and the support structure subject to a 100-year return hurricane are determined. Several types of soil are considered and modeled with a distributed spring system. The results reveal that pile-soil interaction affects dynamics of the turbine support structure significantly, but not the wind rotor dynamics. Designed with proper pile lengths, natural frequencies of the turbine structure in different soils stay outside dominant frequencies of wave energy spectra in both normal operating and hurricane sea states, but stay between blade passing frequency intervals. Hence potential resonance of the turbine support structure is not of concern. A comprehensive Campbell diagram is constructed for safe operation of the offshore turbine in different soils.
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