A COUPLED MODELLING APPROACH FOR THE FAST COMPUTATION OF UNDERWATER NOISE RADIATION FROM OFFSHORE PILE DRIVING

Abstract

This paper presents a computationally efficient modelling approach for the prediction of underwater noise radiation from offshore pile driving. A near-source module is adopted to capture the interaction between the pile, fluid and soil, which is based on a previously developed semi-analytical vibro-acoustic model. This module primarily aims at modelling the sound generation and propagation in the vicinity of the monopile. The Green's tensor for an axisymmetric ring source in a horizontally stratified acousto-elastic half-space emitting both compressional and shear waves is derived using the normal modes and branch line integrations. The boundary integral equations are then formulated based on the reciprocity theorem, which forms the mathematical basis of the far-from-source module for the propagation of the wave field at large radial distances. The complete noise prediction model comprises the two modules, which are coupled through the boundary integral formulation with the input obtained from the near-source module. Model predictions are benchmarked against measurement data from an offshore installation campaign.