Response of suction bucket foundation subjected to wind and earthquake loads on liquefiable sandy seabed

Abstract

Offshore wind turbines (OWTs) are now being built in seismically active regions with the implementation of net-zero emissions of carbon dioxide. Safe operation of OWTs on suction bucket foundation is severely threatened by earthquake-induced liquefaction. This research investigated the performance of the suction bucket foundation supported the OWT in the liquefiable sand under wind and earthquake loads. A series of three-dimensional numerical models were established to perform the nonlinear dynamic analysis, in which the sandy seabed was described by an advanced elastic-plastic constitutive model. Various factors affecting seismic responses of the suction bucket foundation were analyzed, including the wind loads, seismic loads, aspect ratios of suction buckets, and sand densities. The responses were evaluated in terms of accelerations, excess pore water pressure ratios, horizontal displacements, settlements, and rotations of the OWT under wind and earthquake loads. The OWT may suffer a permanent tilt to exceed the serviceability limit state of the OWT due to wind loads, earthquakes, and liquefaction. The deformation mechanism of the suction bucket foundation under wind loads and earthquakes was revealed. The rotation-based proposed design charts were given for checking the design of seismic conditions. These research results can be used in a comparative sense for the design of the OWT in seismically active areas.