Simulating the response of monopile foundation of wind turbines

Undoubtedly, the foundation of a wind turbine is the key component for the safe transfer of the loads acting on the superstructure to the ground. Furthermore, the overall stiffness of the system, which is the most important factor in the design of a wind turbine, may be altered substantially by the potential compliance of the soil and the foundation. Therefore, it is evident that an efficient design of the foundation is required in order to reduce both the risk and the cost of a wind turbine. The current study is involved with the piled foundation of wind turbines, and more specifically with the response of the monopile foundation system, which is one of the most popular foundation methods, especially in the case of offshore wind turbines. To highlight some important aspects of pile design under lateral loading, the problem stated above is examined by utilizing two different methodologies/models: (a) a Winkler foundation model, and (b) a three dimensional (3D) continuous medium finite element model, while the results are compared with experimental data from the literature. The use of the Winkler approach, along with the provisions of the norms for the generation of p-y curves, leads to an overestimation of the soil-pile system stiffness. On the other hand, simple three-dimensional finite element modeling has been proven more capable of predicting the correct soil-pile stiffness. However, a more sophisticated numerical simulation could be performed to take into account the soil-pile interfaces and to incorporate a constitutive law capable to predict accurately the ultimate soil resistance.