Geotechnical design calculations for offshore wind turbine monopile foundations are often conducted using a 1D Winkler model, where the soil-structure interaction under lateral loading is modelled with empirical soil reaction curves (p-y curves). This methodology has been used extensively throughout the geotechnical engineering community but has proven to be somewhat inadequate when modelling a realistic response for the large diameter monopiles used as support for offshore wind turbines. A sensitivity study is presented in this paper to assess the use of PISA (Pile Soil Analysis) springs for monopile design in comparison to traditional p-y curves, which have been derived empirically for much slender piles. The sensitivity study considers typical North Sea soil and loading conditions applied to a recent monopile design. It is observed that PISA springs are stiffer than standard p-y curves, design results and method limitations are discussed in the paper.
Guillaume Melin, Martin U. Østergaard, Søren P. H. Sørensen and Evelina Vaitkune
Keywords: monopile, pile foundation, offshore wind, PISA, sensitivity study
Publisher: DFI