Experimental Modeling of the Seismic Behavior of Offshore Wind Turbines Supported by Gravity-Based Foundation on Liquefiable Soils

Abstract

The increasing global energy demand, depletion of fossil fuel resources, and the ongoing climate crisis have accelerated the transition toward renewable energy sources. Among these, wind energy— particularly offshore wind—has experienced rapid growth due to its high energy potential and low carbon emissions. This study investigates the seismic behaviour of a 5 MW offshore wind turbine supported by a gravity-based foundation resting on liquefiable soil. A 1/75 scale model of the turbine was developed and tested on a shake table within a laminar box to replicate marine and seismic conditions. The experimental setup included five accelerometers, two pore water pressure transducers, and a potentiometer located on the soil surface, as well as an accelerometer on the nacelle of the turbine to monitor structural response. The results revealed notable ground amplification effects and further amplification at the turbine’s nacelle, indicating dynamic interaction between the soil and the structure. The turbine exhibited rotational motion along all three axes during seismic loading. Significant increases in pore water pressure were observed, with localized instances of liquefaction. Following the shaking, the excess pore pressures gradually dissipated, returning to initial levels. These findings contribute to a better understanding of the seismic performance of offshore wind turbines supported by gravity-based foundations in liquefiable soils.