De Vos, Leen4; Frigaard, Peter1; De Rouck, Julien4
1 Department of Civil Engineering, The Faculty of Engineering and Science, Aalborg University, VBN2 Coastal Engineering Research Group, The Faculty of Engineering and Science, Aalborg University, VBN3 Division of Water and Soil, The Faculty of Engineering and Science, Aalborg University, VBN4 unknown
During the last decade, several offshore wind-farms were built and offshore wind energy promises to be a suitable alternative to provide green energy. However, there are still some engineering challenges in placing the foundations of offshore wind turbines. For example, wave run-up and wave impacts cause unexpected damage to boat landing facilities and platforms. To assess the forces due to wave run-up, the distribution of run-up around the pile and the maximum run-up height need to be known. This article describes a physical model study of the run-up heights and run-up distribution on two shapes of foundations for offshore wind turbines, including both regular and irregular waves. The influence of wave steepness, wave height and water depth on run-up is investigated. The measured run-up values are compared with applicable theories and previous experimental studies predicting run-up on a circular pile. The results show that the shape of the foundation substantially affects the maximum run-up level, increasing the expected run-up value. A new relationship between the wave climate (regular and irregular waves) and the run-up is suggested. For this, the velocity stagnation head theory is adjusted and second order Stokes equations are used to calculate the wave kinematics in the crest. The variation of the run-up around the pile is measured and it is found that the position with the lowest run-up level is located under 135°, while the run-up at that position amounts to approximately 40% to 50% of the maximum run-up.
Coastal Engineering, 2007, Vol 54, Issue 1, p. 17-29
Wave Run-Up; Cylindrical Monopile; Conical Monopile; Offshore Wind Turbines; Foundation Physical Model; Spatial Distribution