3D nonlinear dynamic Finite Element analysis of onshore wind turbines on pile foundation resting on liquefiable soils

The latest development of wind turbines in seismic areas, such as East Asia and Californian coast, has increased the importance of their seismic design. High-intensity ground motions can strongly affect serviceability of wind turbines due to earthquake-induced settlements and rotations. In the presence of loose, saturated sandy soils, liquefaction may also become a concern. In such circumstances cyclic soil behaviour needs to be carefully simulated by considering coupled u-p formulations. In this paper, the main results of fully-coupled Finite Element nonlinear dynamic 3D analyses are discussed, where a typical onshore wind turbine on a piled raft foundation resting on liquefiable soils, with piles penetrating into dense sand, is subjected to high-intensity motions triggering liquefaction. Soil behaviour was described through the constitutive model SANISAND. The numerical results were compared to those obtained through a reduced-scale model tested in the centrifuge available at University of Cambridge, thus providing useful insight on the efficacy and reliability of 3D numerical modelling of such systems, which is anticipated to become more and more common in the near future.