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Mitigating Supersonic Underwater Noise
Studies of Impact and Vibratory Pile Driving in Marine Environments
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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.
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Invention/Commercialization
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Pile to Minimize Noise Transmission and Method of Pile Driving Patent Number: 8,622,658 |
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7 Jan 2014
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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.
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Marine Construction Technologies: Creating an Acoustic Barrier to Save Marine Life
Story and video feature by Clare LaFond and Conrado Tapado, posted at the UW Center for Commercialization (C4C) site. |
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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
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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.
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Modeling and visualization of the underwater sound field associated with underwater pile driving Farrell, D.M., and P.H. Dahl, "Modeling and visualization of the underwater sound field associated with underwater pile driving," J. Acoust. Soc. Am., 132, 2061, doi:10.1121/1.4755595, 2012. |
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1 Sep 2012
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As communities seek to expand and upgrade marine and transportation infrastructure, underwater noise from pile driving associated with marine construction is a significant environmental regulatory challenge. This work explores results of different transmission loss models for a site in Puget Sound and the effect of improved understanding of modeling on the extents of zones of influence. It has been observed that most of the energy associated with impact pile driving is less than about 1000 Hz. Here, analysis of the spectral content of pile driving noise is undertaken to ascertain the optimal surrogate frequency to model the broadband nature of the noise. Included is a comparison of a normal mode model, which is motivated by work presented by Reinhall and Dahl [JASA 130, 1209 (2011)], with other methods. A GIS (Geographic Information System) tool, ArcMap, is used to map the sound level over the bathymetry, which has proved to be a useful way of visualizing the impact of the noise.
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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. |
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1 Sep 2012
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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.
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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). |
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2 Jul 2012
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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). |
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2 Jul 2012
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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). |
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2 Jul 2012
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Underwater Mach wave radiation from impact pile driving: Theory and observation Reinhall, P.G., and P.H. Dahl, "Underwater Mach wave radiation from impact pile driving: Theory and observation," J. Acoust. Soc. Am., 130, 1209-1216, doi:10.1121/1.3614540, 2011 |
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1 Sep 2011
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The underwater noise from impact pile driving is studied using a finite element model for the sound generation and parabolic equation model for propagation. Results are compared with measurements using a vertical line array deployed at a marine construction site in Puget Sound. 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 after impact at supersonic speed. The predictions of vertical arrival angle associated with the Mach cone, peak pressure level as function of depth, and dominant features of the pressure timeseries compare well with corresponding field observations.
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Acoustic radiation during marine pile driving Reinhall, P.G. and P.H. Dahl, "Acoustic radiation during marine pile driving," J. Acoust. Soc. Am., 129, 2460, doi:10.1121/1.3588091, 2011. |
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1 Apr 2011
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Pile driving in water produces extremely high sound levels in the surrounding under water environment. Sound levels as high as 220 dB re 1 micro Pa 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 sound pressures. 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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Acoustic transmission loss in industrial pile driving Stockham, M.L., P.H. Dahl, and P.G. Reinhall, "Acoustic transmission loss in industrial pile driving," J. Acoust. Soc. Am., 129, 2461, doi:10.1121/1.3588094, 2011. |
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1 Apr 2011
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Industrial pile driving is a source of high-level underwater noise and new understanding of its effects on the behavior and health of marine mammals and fish has motivated numerous regulations intended to limit these effects. Of primary importance is to identify a suitable transmission loss model to predict where, given a certain source level, the noise produced by the pile driving reaches regulatory thresholds. In November 2009, data were collected from a marine construction site in the Puget Sound. Measurements at two ranges (8 and 12 m) from the pile being driven were taken using a nine hydrophone vertical line array (VLA). Concurrently, at a range of approximately 120 m, there was also a single hydrophone at a depth of 5 m (sensitive to frequencies greater than 10 kHz). By comparing the levels at the VLA to the more distant hydrophone across a number of pile strikes (each forming a identifiable short- and far-range pair), the transmission loss can be estimated. These results are in turn modeled using an approach based on the parabolic wave equation.
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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. |
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1 Apr 2011
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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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Acoustic radiation from a submerged pile during pile driving Reinhall, P.G., and P.H. Dahl, "Acoustic radiation from a submerged pile during pile driving," In Proceedings, MTS/IEEE OCEANS 2010, Seattle, 20-23 September, doi:10.1109/OCEANS.2010.5663872 (MTS/IEEE, 2010). |
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20 Sep 2010
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Pile driving with an impact hammer is inherently a transient process and can produce very high sound levels. It is shown that the underwater noise during pile driving is due to a radial expansion of the pile that propagates along the pile after impact. This structural wave produces a wave front cone in the water, and a downward moving wave that continues into the sediment. An upward moving wave front is produced in the sediment after the first reflection of the structural wave, which is subsequently transmitted into the water. This process is repeated to produce an acoustic field that consists of wave fronts with alternating positive and negative angles. Good agreement in the estimate of the angles was obtained between a finite element wave propagation model and measurements taken during a full scale pile driving study.
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Characterizing underwater noise from industrial pile driving at close range Stockham, M.L., P.H. Dahl, and P.G. Reinhall, "Characterizing underwater noise from industrial pile driving at close range," In Proceedings, MTS/IEEE OCEANS 2010, Seattle, 20-23 September, doi:10.1109/OCEANS.2010.5663899 (MTS/IEEE, 2010). |
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20 Sep 2010
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Acoustic radiation in the water surrounding a ferry terminal pile driving project has been characterized based on 1/3-octave band filtering. The pressure field at approximately 10 meters is shown to be depth dependent based on data captured using a vertical line array. Decibel measurements of underwater sound are often expressed in reference to several non-interchangeable units, a summary of the differences of these references is presented.
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Less bang, more bubbles Scientific American, Charles Q. Choi Light curtains of air may protect fish from the din of humans. The bubbles alone may not fully solve the problem. They may dampen sound traveling through the water from above, but about 10 percent of the noise from underwater pile driving would still get transmitted up from the seabed, says acoustician Peter Dahl of the University of Washington. |
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1 Sep 2011
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