Cyclic p-y model for pile-soil foundation interaction of offshore wind turbine in clay stratum

Offshore wind turbines suffer from cyclic loading such as wind, waves and other loads during their service period, and the stability of its pile foundation is a key issue in design. The p-y curve method is simple and fast for calculation, and it is the most commonly used method in the analysis of lateral loaded piles. In this paper, a slice model of pile-soil interaction was established and the finite element analysis was systematically carried out. The p-y curves of the full-flow failure zone of piles with different stiffness were obtained. The calculation results showed that for the same pile length, the pile diameters had an impact on the strength and stiffness of the static p-y curves. The larger the pile diameter was, the greater the stiffness shown by the p-y curve was, and the greater the ultimate soil resistance on the pile side was. Under the same cyclic amplitude, the cumulative displacement increased with the increase of pile diameter, and a unified p-y curve could be obtained after normalizing the ultimate soil resistance and cumulative displacement at the pile side by the ultimate soil resistance and pile diameter. Based on this drawing, we introduced a new mapping rule and a plastic modulus expression under the framework of bounding surface theory to build a cyclic p-y model suitable for clay stratum. Finally, the model was verified by centrifuge tests. The results show that the model can effectively simulate the response of pile foundations under cyclic loading. This study provides a new idea and method for the construction of p-y model for pile foundation of offshore wind turbines.