Year

2023

Season

Summer

Paper Type

Master's Thesis

College

College of Computing, Engineering & Construction

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Engineering

NACO controlled Corporate Body

University of North Florida. School of Engineering

Committee Chairperson

Raphael Crowley, Ph.D., P.E

Second Advisor

Ryan Shamet, Ph.D.

Rights Statement

http://rightsstatements.org/vocab/InC/1.0/

Third Advisor

James Gelsleichter, Ph.D.

Department Chair

Alan Harris, Ph. D.

College Dean

William Klosermeyer, Ph.D.

Abstract

In recent years, the potential impact on marine organisms of sound waves generated by pile driving has become a growing concern. Previous research in this field has predominantly relied upon single-strike averages to analyze underwater sound data. However, it was unclear from these analyses if or how much attenuation may vary during typical pile drives. This study involved collecting sound data from multiple locations during a given pile driving operation at the same time and used these data to analyze sound decay from each hammer blow individually. In addition to this, computational fluid dynamics (CFD) was used to better understand the components that may influence attenuation variability. The results reveal that each hammer blow exhibits a unique sound decay curve characterized by a distinct sound attenuation coefficient. Interestingly, these coefficients demonstrate variability within a drive event. Several potential factors contributing to these variations are identified, including the type of pile, variation in geotechnical conditions, hammer cushion, pile cushion, and channel properties. However, despite the variability observed in attenuation coefficients from one blow to another, an apparent relationship was consistently observed between source-level and attenuation – thereby providing additional basis for a previously proposed empirical model for predicting underwater attenuation. This emphasizes the need for further research in establishing exactly whether source level influences sound attenuation or if mode stripping variation is governed by additional sound attenuation.

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