Numerical determination of equivalent damping parameters for a finite element model to predict the underwater noise due to offshore pile driving
Invited paper
University of Technology Hamburg
Monday 1 june, 2015, 16:20 - 16:40
0.2 Berlin (90)
Abstract:
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.