Preface for special issue on local scour and soil liquefaction around offshore windfarm foundations

The offshore wind industry has been Hourishing globally over the past few decades because of the increasing demand for renewable energy.Different types of foundations have been adopted,including monopiles,gravity・based structures,tripods,jackets,and pile groups for traditional offshore wind-farm foundations,as well as drag-embedment anchors(DEAs)with associated subsea structures(i.e.,tensioners,clump weights,and chains)for foundations of floating windfarms.Local scour and liquefaction issues are significant to the security of offshore windfarm foundations and foundation stability(Guan et al.,2019;Whitehouse et al.,2011;Zhu et al.,2018).