Prediction of offshore impact pile driving noise using numerical and analytical approach

Abstract

Noise generated by offshore impact pile driving can radiate into and propagate through the air, water, and sediment. Predicting noise levels around the support structures at sea is required to estimate the effects of the noise on marine life. We have been investigated acoustic impact using our previously verified coupled Finite Element (Commercial FE code Abaqus) and Monterey Miami Parabolic Equation (2D MMPE) models [J. Acoust. Soc. Am. 131(4), 3392 (2012) and J. Acoust. Soc. Am. 133, 3419 (2013)]. A simple analytical model for the impact pile driving noise is developed to reduce computation cost and modeling effort when compared to the numerical model. In the present study, we are developing a Matlab based analytical model to calculate the Receive Levels (RL) in water. This analytical model solves simplified Donnell’s equation, i.e., governing equation for the thin cylindrical shell using the modal superposition approach assuming azimuthal symmetry. It solves the Helmholtz or Kirchhoff integral equation to evaluate the acoustic pressure field. We will compare the results of the coupled FE-MMPE numerical model and the Matlab based analytical model and discuss their advantages and disadvantages. [Work sponsored by the Link Foundation Ocean Engineering and Instrumentation Ph.D. Fellowship program.]