Acoustic radiation during marine pile driving.

Jan. 31, 2015

AUTHORS

Per G. Reinhall and Peter H. Dahl

ABSTRACT

Pile driving in water produces extremely high sound levels in the surrounding under water environment. Sound levels as high as 220 dB re 1 μPa are not uncommon 10 m away from a steel pile as it is driven into the sediment with an impact hammer. The primary source of underwater sound originating from pile driving is associated with compression of the pile. The pile is struck and the Poisson effect produces a radial displacement motion in the pile that will propagate downward at a computed speed comparable to but less than the longitudinal wave speed in steel. It is shown, using both finite element analysis and modeling based on the parabolic wave equation, that this radial motion of the pile is responsible for the ensuing high underwater soundpressures. It is also shown that the radial motion of the pile is transmitted into the water, either directly from the pile or indirectly via the bottom sediment that is in contact with the pile. A dominant feature of the resulting sound field is an axisymmetric Mach cone with apex traveling along with the pile deformation wave front.

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http://scitation.aip.org/content/asa/journal/jasa/129/4/10.1121/1.3588091

"By reducing underwater noise from pile driving by 20 dB, implementation of MCT’s technology could potentially reduce the Zone of Influence and required marine mammal monitoring, expedite consultation processes with the Services, and minimize construction delays due to the proximity of marine mammals."
Cameron Fisher, Biological Lead, 48 North Solutions, Inc.

Hear the difference

Recorded from hydrophone deployed at 10m during subscale testing of 8" steel piles in Seattle, Washington in 2013.

You are hearing 4 strikes of a standard pile followed by 4 strikes of a Reinhall Pile™. Notice the difference.