Researchers

Peter Dahl

Senior Principal Engineer

Acoustics Department

APL-UW

Professor, Mechanical Engineering

Per Reinhall

Professor and Chair

UW Department of Mechanical Engineering

David Dall'Osto

Senior Research Scientist/Engineer

Acoustics Department

APL-UW

Dara Farrell

Predoctoral Research Associate I

Acoustics Department

APL-UW

Alexander Soloway

Research Assistant

Acoustics Department

APL-UW

Funding

WA Department of Transportation

Washington Sea Grant

Mitigating Supersonic Underwater Noise

Studies of Impact and Vibratory Pile Driving in Marine Environments

We really have two goals here: one is to study the nature of the underwater sound field as it’s generated at the pile. By that, I mean what is its direction, angular distribution, frequency content, and strength? The second goal is to study how sound propagates away from the pile.

The zone of sound that can potentially cause impact to marine mammals and how far that zone extends out from the pile-driving region is not well known.

Invention/Commercialization

Pile to Minimize Noise Transmission and Method of Pile Driving

Patent Number: 8,622,658

More Info

7 Jan 2014

A pile and method for driving a pile includes a pile having a structural outer tube, and an inner member disposed generally concentrically with the outer tube. The outer tube and inner member are fixed to a driving shoe. The pile is constructed and driven such that the pile driver impacts only the inner member. The impact loads are transmitted to the driving shoe to drive the pile into the sediment, such that the outer tube is thereby pulled into the sediment. In a particular embodiment the outer tube is formed of steel, and the inner member also comprises a steel tube. In an alternative embodiment one or both of the inner member and the outer tube are formed of an alternative material, for example, concrete. In an embodiment, the outer tube has a recess that captures a flange on the inner member. In an embodiment the outer tube is attached to the inner member with an elastic spring.

More About This Research

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Attenuation of pile driving noise using a double walled sound shield

Reinhall, P.G., and P.H. Dahl, "Attenuation of pile driving noise using a double walled sound shield," J. Acoust. Soc. Am., 132, 2034, doi:10.1121/1.4755475, 2012.

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1 Sep 2012

Pile driving in water produces high sound levels in underwater environments. The associated pressures are known to produce deleterious effects on both fish and marine mammals. We present an evaluation of the effectiveness of surrounding the pile with a double walled sound shield to decrease impact pile driving noise. Four 32 m long, 76 cm diameter piles were driven 14 m into the sediment with a vibratory hammer. A double walled sound shield was then installed around the pile, and the pile was impact driven another 3 m while sound measurements were obtained. The last 0.3 m was driven with the sound shield removed, and data were collected for the untreated pile. The sound field obtained by finite element analysis is shown to agree well with measure data. The effectiveness of the sound shield is found to be limited by the fact that an upward moving Mach wave is produced in the sediment after the first reflection of the deformation wave against the bottom end of the pile. The sound reduction obtained through the use of the sound shield, as measured 10 meters away from the pile, is shown to be approximately 12dB dB re 1 µPa.

On the Mach wave effect in impact pile driving, its observation, and its influence on tramsmission loss

Dahl, P.H., and P.G. Reinhall, "On the Mach wave effect in impact pile driving, its observation, and its influence on tramsmission loss," J. Acoust. Soc. Am., 132, 2033, doi:10.1121/1.4755474, 2012.

More Info

1 Sep 2012

Pile driving in water produces extremely high sound pressure levels in the surrounding underwater environment of order 10 kPa at ranges of order 10 m from the pile that can result in deleterious effects on both fish and marine mammals. In Reinhall and Dahl [J. Acoust. Soc. Am. 130, 1209-1216, Sep. 2011] it is shown that the dominant underwater noise from impact driving is from the Mach wave associated with the radial expansion of the pile that propagates down the pile at speeds in excess of Mach 3 with respect to the underwater sound speed. In this talk we focus on observations of the Mach wave effect made with a 5.6 m-length vertical line array, at ranges 8-15 m in waters of depth ~12.5 m. The key observation is the dominant vertical arrival angle associated with the Mach wave, ~17 deg., but other observations include: its frequency dependence, the ratio of purely waterborne energy compared with that which emerges from the sediment, and results of a mode filtering operation which also points to the same dominant angle. Finally, these observations suggest a model for transmission loss which will also be discussed.

Attenuation of noise from pile driving in water using an acoustic shield

Reinhall, P., and P. Dahl, "Attenuation of noise from pile driving in water using an acoustic shield," Proceedings, 11th European Conference on Underwater Acoustics, 2-6 July, Edinburgh, 368-375 (Institute of Acoustics, 2012).

2 Jul 2012

Observations of underwater sound from impact pile driving using a vertical line array

Dahl, P., and P. Reinhall, "Observations of underwater sound from impact pile driving using a vertical line array," Proceedings, 11th European Conference on Underwater Acoustics, 2-6 July, Edinburgh, 1340-1347 (Institute of Acoustics, 2012).

2 Jul 2012

Transmission loss and range, depth scales associated with impact pile driving

Dahl, P., P. Reinhall, and D. Farrell, "Transmission loss and range, depth scales associated with impact pile driving," Proceedings, 11th European Conference on Underwater Acoustics, 2-6 July, Edinburgh, 1860-1867 (Institute of Acoustics, 2012).

2 Jul 2012

Observations and parabolic wave modeling of underwater pile driving impact noise

Dahl, P.H., and P.G. Reinhall, "Observations and parabolic wave modeling of underwater pile driving impact noise," J. Acoust. Soc. Am., 129, 2461, doi: 10.1121/1.3588093, 2011.

More Info

1 Apr 2011

Pile driving in water produces extremely high sound levels in both surrounding air and underwater environments. In a companion work [Reinhall and Dahl] it is shown using finite element simulation that for underwater case the primary sound signal originates from a compression wave traveling down the pile at a speed in excess of Mach 3. In this work, we present measurements pile driving impact noise made from a marine construction site in Puget Sound using a vertical line array (VLA) positioned at ranges 815 m from full-scale impact pile driving. The measurements are modeled using the parabolic wave equation approach for which synthetic time series are generated (bandwidth 50-2050 Hz). The simulation is achieved by way of a phased array of point sources, representing one source traveling down the pile at supersonic speed. Pile end reflections are included and the process is repeated with both an up- and down-traveling time-delayed sources. With the field computed in this manner, excellent agreement is achieved between model and observations of peak pressure level, and the compression wave speed is also confirmed by way of arrival angle estimation using the VLA. Implications on transmission loss are also discussed.

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