Calculations of Axial Pile Capacity under Sustained Cyclic Loading for Offshore Wind Turbine Foundations

In the paper, a finite element analysis procedure is proposed for the calculation of axial pile capacity under sustained cyclic loading for offshore wind turbine foundations. In the numerical simulation, an undrained elastic-plastic model considering the cyclic degradation of clayey soils is adopted, and this model is obtained from data analysis on a series of static and cyclic undrained triaxial tests of saturated soft clay. Based on this model, a number of numerical simulations are conducted by a commercially available finite element software at different cyclic load levels. The ultimate axial bearing capacity and axial stiffness of single pile resisting axial cyclic load calculated by the finite element analysis have a good consistency with the model tests data in Poulos (1979), which verifies the reasonability and reliability of the proposed numerical procedure. Afterwards, the axial bearing capacities of pile foundation of Shanghai Donghai-bridge offshore wind farm under cyclic load are studied with the application of the proposed numerical method. The proposed method will serve as a useful tool for engineering design.