Abstract: As one type of green energy, offshore wind power has been paid more and more attention. There are extensive research focused on local scour of the monopile foundation. In this paper, a model of offshore wind turbine system with different scour depths is established. The static and dynamic analysis of the model is carried out. Results are in good agreement with the previous scouring model test. As the increase of scour depth, the maximum horizontal displacement, the maximum horizontal stress and the maximum bending moment values of the support system increase gradually. When the scour depth is twice the pile diameter, the maximum horizontal displacement, stress and bending moment are increased by 3.61%, 12.7% and 10.3% respectively, comparing to those under the condition without local scour. The natural frequency of the system decreases with increase of scour depth, and frequencies of high order are more susceptible. Scour around pile foundation has a significant impact on dynamic characteristics of system. The horizontal displacement at the top of the tower constantly increases with scour depth. The influence of scour on the bearing performance of the supporting system must be considered in the design of offshore wind turbines.

Key words: local scour, monopile foundation, scour depth, P-y curves, dynamic response