Publication Abstract

International Symposium on Frontiers in Offshore Geotechnics, (DFI)

Numerical Analysis of Offshore Wind Turbine Foundations in Dense Sand Considering Partial Drainage
S. Whyte, M. Rattley, M. Ramos Da Silva, C. M. Martin, H. J. Burd and C. Erbrich

Analysis models for the design of offshore piles and suction buckets in sandy seabed soils typically assume fully drained soil behaviour for all loading rates. However, for wind turbine support applications, the dimensions of installed foundations are tending to increase as larger generating plants are deployed. For relatively large foundations of this sort, the assumption of drained behaviour at sand sites may not be valid in all cases. This paper presents coupled flow-deformation finite element analyses (FEA) of suction bucket and monopile foundations installed in representative North Sea dense sand profiles, subjected to realistic offshore wind turbine loading conditions. The modelling study provides a means of investigating the influence of assumed soil drainage conditions and loading rates on the overall foundation response, and describes key considerations which should be included in such numerical analyses. The importance of considering cavitation pressure limits in the analyses is discussed and a simple approach is demonstrated for considering cavitation within coupled flowdeformation FEA, with an example given for lateral loading of a monopile in dense sand. It is also demonstrated that careful formulation and calibration of the adopted constitutive model is essential to ensure accurate predictions of foundation response for different loading rates, highlighting that careful consideration should be given to the features included within the constitutive model.

 article #3468; publication #1069 (IC-ISFOG21)