Numerical determination of equivalent damping parameters for a finite element model to predict the underwater noise due to offshore pile driving

Invited paper

Kristof Heitmann

University of Technology Hamburg

Monday 1 june, 2015, 16:20 - 16:40

0.2 Berlin (90)

Due to the massive construction of offshore wind parks in the German North Sea, an increasing attention has been directed to underwater noise. In particular, to protect marine life, limiting values for the sound pressure level during construction have been introduced by the German authorities. State of the art for the erection of the wind turbines is impact pile driving. Hence, a reliable prediction technique for the noise due to pile driving with an impact hammer becomes increasingly important. At present, different numerical methods are under development for these forecasts. The most common technique used to calculate the sound pressure in the area close the pile is the finite element method. In several publications, an equivalent damping in the embedded part of the pile is chosen to take the losses, e.g. the plasticity of the soil, into account. In this contribution, a method to determine the equivalent damping with the “Wave Equation Analysis of Pile Driving” (WEAP) is shown. During a drivability study performed with WEAP, the Rayleigh damping coefficients are extracted. Finally, these coefficients are validated by comparing modelling results based on the finite element method (FEM) with measured data.

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