Beam forming of the underwater sound field from impact pile driving

Dahl, Peter H.; Reinhall, Per G.

doi:10.1121/1.4807430

Cited by 12 publications

(9 citation statements)

References 11 publications

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“…In the case of pile driving, the stress wave in the pile constitutes the moving source. These observations were soon after confirmed by beam forming analysis of measured data [89,90]. The modelling approach introduced by Reinhall and Dahl [83] was subsequently adopted by other researchers [91][92][93][94][95][96][97], i.e., a FEM was employed for the sound generation and a propagation algorithm was applied for wave field predictions at larger distances.…”

Section: First Generation Models: the Fluid Approximation Of The Seabedmentioning

confidence: 92%

Underwater Noise Emission Due to Offshore Pile Installation: A Review

Tsouvalas

2020

Energies

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The growing demand for renewable energy supply stimulates a drastic increase in the deployment rate of offshore wind energy. Offshore wind power generators are usually supported by large foundation piles that are driven into the seabed with hydraulic impact hammers or vibratory devices. The pile installation process, which is key to the construction of every new wind farm, is hindered by a serious by-product: the underwater noise pollution. This paper presents a comprehensive review of the state-of-the-art computational methods to predict the underwater noise emission by the installation of foundation piles offshore including the available noise mitigation strategies. Future challenges in the field are identified under the prism of the ever-increasing size of wind turbines and the emerging pile driving technologies.

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Section: First Generation Models: the Fluid Approximation Of The Seabedmentioning

confidence: 92%

Underwater Noise Emission Due to Offshore Pile Installation: A Review

Tsouvalas

2020

Energies

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“…Distinguishing properties of the dominant underwater pressure field from impact pile driving are explained reasonably well in terms of depth 1 and angular dependence. 3 For vibratory pile driving, however, any sense of linesource spatial coherency is lost or at the very least rendered vastly more complex with effects not observable in the ensuing pressure field. There are, however, distinguishing properties in the mean-square pressure field from vibratory pile driving such as the third-octave band patterns (Fig.…”

Section: Third-octave Band Mean-square Pressure Versus Depth and mentioning

confidence: 99%

“…The latter can produce extremely high sound pressures in the surrounding underwater environment that have necessitated environmental regulations designed to protect marine life. For example, several recent studies [1][2][3][4][5] report on and analyze the high peak-pressure levels from impact pile driving generated by the coherent Mach wave effect. The underwater sound field associated with vibratory pile driving, although of lower level than impact pile driving, is also of biological concern and of regulatory consequence, and much effort is currently directed toward underwater noise monitoring during vibratory pile driving particularly when it occurs in sensitive marine habitats.…”

Section: Introductionmentioning

confidence: 99%

The underwater sound field from vibratory pile driving

Dahl

Dall’Osto

Farrell

2015

The Journal of the Acoustical Society of America

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Underwater noise from vibratory pile driving was observed using a vertical line array placed at range 16 m from the pile source (water depth 7.5 m), and using single hydrophones at range 417 m on one transect, and range 207 and 436 m on another transect running approximately parallel to a sloping shoreline. The dominant spectral features of the underwater noise are related to the frequency of the vibratory pile driving hammer (typically 15-35 Hz), producing spectral lines at intervals of this frequency. The mean-square pressure versus depth is subsequently studied in third-octave bands. Depth and frequency variations of this quantity observed at the vertical line array are well modeled by a field consisting of an incoherent sum of sources distributed over the water column. Adiabatic mode theory is used to propagate this field to greater ranges and model the observations made along the two depth-varying transects. The effect of shear in the seabed, although small, is also included. Bathymetric refraction on the transect parallel to the shoreline reduced mean-square pressure levels at the 436-m measurement site.

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“…Conversion factors in our study therefore varied by more than an order of magnitude through a piling cycle ( Figure 6) and exceeded 10% during the piling soft starts designed to minimize noise exposure at the beginning of each sequence. Previous use of the 0.5% conversion factor has been based largely upon two empirical studies (Robinson et al, 2007;Dahl & Reinhall 2013), both in shallow waters of <15 m. In each case, there were important differences in pile installation techniques that may explain why our observed conversion factors were higher when using pin piles to install jackets in deeper waters. In Robinson et al (2007) near-field measurements made during the installation of a 65 m × 2 m pile at an experimental test site reported that 0.3% of hammer energy was converted to sound with a highly linear relationship between pulse energy and hammer energy (see Figure 10 in Robinson et al [2007]).…”

Section: Variation In Piling Noise Through the Piling Sequencementioning

confidence: 88%

Balancing risks of injury and disturbance to marine mammals when pile driving at offshore windfarms

Thompson

Graham

Cheney

et al. 2020

Ecol Sol and Evidence

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1. Offshore windfarms require construction procedures that minimize impacts on protected marine mammals. Uncertainty over the efficacy of existing guidelines for mitigating near-field injury when pile-driving recently resulted in the development of alternative measures, which integrated the routine deployment of acoustic deterrent devices (ADD) into engineering installation procedures without prior monitoring by marine mammal observers. 2. We conducted research around the installation of jacket foundations at the UK's first deep-water offshore windfarm to address data gaps identified by regulators when consenting this new approach. Specifically, we aimed to (a) measure the relationship between noise levels and hammer energy to inform assessments of near-field injury zones and (b) assess the efficacy of ADDs to disperse harbour porpoises from these zones. 3. Distance from piling vessel had the biggest influence on received noise levels but, unexpectedly, received levels at any given distance were highest at low hammer energies. Modelling highlighted that this was because noise from pin pile installations was dominated by the strong negative relationship with pile penetration depth with only a weak positive relationship with hammer energy. 4. Acoustic detections of porpoises along a gradient of ADD exposure decreased in the 3-h following a 15-min ADD playback, with a 50% probability of response within 21.7 km. The minimum time to the first porpoise detection after playbacks was > 2 h for sites within 1 km of the playback. 5. Our data suggest that the current regulatory focus on maximum hammer energies needs review, and future assessments of noise exposure should also consider foundation type. Despite higher piling noise levels than predicted, responses to ADD playback suggest mitigation was sufficiently conservative. Conversely, strong responses of porpoises to ADDs resulted in far-field disturbance beyond that required to mitigate injury. We recommend that risks to marine mammals can be further minimized by (1) optimizing ADD source signals and/or deployment schedules to minimize broad-scale This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Beam forming of the underwater sound field from impact pile driving

Cited by 12 publications

References 11 publications

Underwater Noise Emission Due to Offshore Pile Installation: A Review

Underwater Noise Emission Due to Offshore Pile Installation: A Review

The underwater sound field from vibratory pile driving

Balancing risks of injury and disturbance to marine mammals when pile driving at offshore windfarms

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