Recent growing demand for wind energy has prompted the industry to evaluate the use of Offshore Wind Turbines (OWT) in deep waters where the floating wind turbines are preferable to the bottom-fixed solutions. While the movements of anchors in catenary moorings during earthquakes may not pose a significant threat to the performance of the structure, the loss of strength in sand due to liquefaction can lead to the anchor pull-out in taut or TLP moorings. This paper aims at investigating the potential use of advanced liquefaction modeling in assessment of the performance of anchor piles in taut and TLP moorings in particular for floating offshore wind turbines during the liquefaction arising from different earthquake shakings. The software FLAC3D is used to conduct the nonlinear dynamic analyses using SANISAND constitutive model for saturated sand. Excess pore pressure due to earthquake shaking and earthquake-induced displacements are estimated at various points in the soil medium containing an anchor pile model. The results show that the anchor experiences a level of upward displacement that may not lead to the anchor pull-out during liquefaction; however, the holding capacity of the anchor may reduce largely after the earthquake.
Pourya Kazemi Esfeh, Laura Govoni and Amir M. Kaynia
Keywords: Liquefaction, Anchor piles, seismic response, taut mooring, TLP mooring, floating offshore structures
Publisher: DFI