On seismic protection of wind turbine foundations founded on liquefiable soils

Abstract

Wind turbine structures can be susceptible to damage from earthquake loading due to large overturning moments at the foundation level. As the wind energy market expands to seismically active parts of the world, it becomes important to evaluate the seismic behaviour of these structures. Especially, earthquake-induced liquefaction can be important when wind farms are located on sites with marginal soil conditions such as loose, saturated sands or non-plastic silts. Reduction of stiffness during liquefaction can cause excessive foundation settlement and/or rotation. Thus, suitable mitigation methods should be investigated. This paper discusses the seismic behaviour of the wind turbine on liquefiable soil and the effectiveness of the stone column-based liquefaction mitigation method. Two geotechnical centrifuge tests were conducted with and without stone columns for a model wind turbine on a circular raft foundation. The results show that stone columns can significantly reduce both the settlement and rotation of the raft.