PhD Project: Instability of Offshore Foundations for Wind Turbines on Deep Water

  • Madsen, Søren, (Projektdeltager)
  • Andersen, Lars Vabbersgaard, (Projektdeltager)
  • Ibsen, Lars Bo (Projektdeltager)

Beskrivelse

In the present years, there is an increased focus on offshore wind farms. The expenses related to foundations constitute about one third of the total cost of an offshore wind farm. When wind turbines are located on deeper water, the cost of the foundations will increase even further. Thus a new technology is needed to reduce the total cost of offshore wind turbines. This could be the bucket foundation, also named “suction caisson”.



The installation of the bucket foundation is initially caused by self-weight penetration. Subsequent suction is applied inside the bucket. The suction creates a pressure differential across the bucket lid, which increases the downward force on the bucket while reducing the skirt tip resistance.



The geometry of the bucket foundation is a thin shell structure. As the water depth increases, the diameter of the suction caisson also increases and the aspect ratio between the caisson diameter and the wall thickness becomes very large. Thus instability, in form of buckling, becomes a crucial issue during installation.



During installation the bucket skirt becomes partly embedded and the degree of skirt fixation increases. The effect of the lateral restraint offered by the surrounding soil on the hydrostatic buckling pressures will be investigated in this study.



Furthermore this study will hopefully result in an alternative shape/design of the suction caisson, which has a smaller risk of buckling under high pressure.

StatusAfsluttet
Effektiv start/slut dato15/12/201015/12/2013