Local scour at monopile foundations of offshore wind turbines is one of the most critical structural stability issues.This article reviews the contemporary methods of scour countermeasures at monopile foundations.These methods include armouring countermeasures(e.g.,riprap protection)to enhance the anti-scour ability of the bed materials and flow-altering countermeasures(e.g.,collars and sacrificial piles)to reduce downflow or change flow patterns around the monopiles.Stability number and size-selection equations for riprap armour layers are summarised and compared.Moreover,other alternative methods to riprap are briefly introduced and presented.A typical graph of the scour depth reduction with different collar sizes and elevations under specific test conditions is summarised and compared with a plot for a pile founded on a caisson.Reduction rates for different flow-altering countermeasures,including the collar,are listed and compared.A newly developed soil improvement method,namely microbially induced calcite precipitation(MICP),is also reviewed and introduced as a scour protection method.As a popular bio-soil treatment method,MICP has a good potential as a scour countermeasure method.Bio-soil treatment methods and traditional armouring methods are defined as active and passive soil enhancement scour countermeasures,respectively.

Department of Civil and Environmental Engineering,The University of Auckland,Auckland 1010,New Zealand;State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University,Nanjing 210098,China;College of Harbor,Coastal and Offshore Engineering,Hohai University,Nanjing 210098,China;School of the Environment and Safety Engineering,Jiangsu University,Zhenjiang 212013,China

[1]Zi-hao Tang;Bruce Melville;Naresh Singhal;Asaad Shamseldin;Jin-hai Zheng;Da-wei Guan;Liang Cheng-.Countermeasures for local scour at offshore wind turbine monopile foundations:A review)[J].水科学与水工程,2022(01):15-28

monopile,armouring,riprap,downflow,monopiles,armour

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