2019_programme: UNDERWATER NOISE GENERATED BY OFFSHORE PILE DRIVING: A PILE-SOIL-WATER VIBROACOUSTIC MODEL BASED ON A MODE MATCHING METHOD
- Session: 15. Acoustics of marine renewable energy developments
Organiser(s): Robinson Stephen, Lepper Paul, Blondel Philippe
- Lecture: UNDERWATER NOISE GENERATED BY OFFSHORE PILE DRIVING: A PILE-SOIL-WATER VIBROACOUSTIC MODEL BASED ON A MODE MATCHING METHOD
Paper ID: 936
Author(s): Tsouvalas Apostolos, Peng Yaxi , Metrikine Andrei
Presenter: Peng Yaxi
Presentation type: oral
Abstract: Anthropogenic underwater noise caused by offshore pile driving has raised serious environmental concerns in recent years. Several studies have shown that the impulsive sound generated by impact piling can be harmful to marine fauna. The offshore industry strives to keep the noise levels to within acceptable limits in order to comply with the regulations. To assist the involved parties in the assessment of the noise levels to be expected during the installation phase of foundation piles, underwater noise prediction becomes essential. \nIn this paper, a pile-water-soil vibroacoustic model is developed for the prediction of underwater noise from offshore pile driving. The complete model consists of two modules: i) a near-source module capturing the pile-water-soil interaction with sound generation and propagation in the vicinity of the pile; ii) a far-from source module aiming at the propagation of the wave field at a larger distance. In the first module, the pile is modelled as a thin shell whereas the water-seabed domain as a layered acousto-elastic continuum of finite depth. The solution to the coupled problem is based on a dynamic sub-structuring, mode matching technique, which ensures the exact satisfaction of the interface conditions between the pile and the surrounding media and the full consideration of the forced equations of motion of the shell subjected to a hammer impact. In the far-from-source module, the environment is modelled as a fluid layer overlaying a layered elastic half-space. The complete wave field is represented by a finite sum of complex-valued modes and wavenumber integrations around the Ewing- Jardetzky-Press (EJP) branch cuts. A frequency-dependent soil material damping is included in order to capture an equivalent elastic representation of the proper wave attenuation in a water-saturated poroelastic seabed. Model predictions are benchmarked against available data from measurement campaigns published in the scientific literature.\n
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- Corresponding author: Ms Peng Yaxi
Affiliation: Delft University of Technology
Country: Netherlands
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