Underwater Mach wave radiation from impact pile driving: Theory and observation

Reinhall, Per G.; Dahl, Peter H.

doi:10.1121/1.3614540

Cited by 109 publications

(111 citation statements)

References 6 publications

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“…For offshore wind turbines this can be achieved by selecting other foundation types, such as gravity-based foundations, or alternative installation procedures (Koschinski & Lüdemann 2014). Modification of the pile-driving procedure itself is another alternative, and systems that prevent generation of the supersonic wave in the pile, which is a main source of noise in the water (Reinhall & Dahl 2011), are under development. The second method is to reduce the sound energy propagated into the surrounding environment.…”

Section: Introductionmentioning

confidence: 99%

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Dähne¹,

Tougaard²,

Carstensen³

et al. 2017

Mar. Ecol. Prog. Ser.

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Effects of constructing the DanTysk offshore wind farm (German Bight, 80 turbines, 6 m diameter foundations) were studied by passive acoustic monitoring of pile-driving noise and harbour porpoise Phocoena phocoena echolocation. An acoustic deterrence device (seal scarer) was used to protect porpoises from hearing loss and bubble curtains were used to attenuate the pile-driving noise. Porpoise occurrence, quantified by echolocation signals, decreased when the seal scarer was engaged, during pile driving and up to 5 h after pile driving stopped. This effect extended out to 12 km, less than the 18−25 km reported from other pile drivings performed without bubble curtains. The bubble curtains thus effectively reduced the temporary habitat loss and risk of hearing loss. The 2 bubble curtains each attenuated the noise by between 7 and 10 dB, when used separately, and 12 dB when used together. Attenuation was most pronounced above 1 kHz, where the pile-driving noise at larger distances was comparable to or lower than ambient noise. This suggests that noise regulation should be based on frequency-weighted sound levels in addition to broadband levels, to assure that mitigation measures are effective in reducing impact on animals and not only in fulfilling legal requirements. The strong reaction to the seal scarer raises concern that it may surpass the reactions to the pile-driving noise itself, when operating with bubble curtains, and calls for a re-evaluation of the specifications of seal scarer sounds.

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Section: Introductionmentioning

confidence: 99%

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Dähne¹,

Tougaard²,

Carstensen³

et al. 2017

Mar. Ecol. Prog. Ser.

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“…Vibrations of impacted poles lead to high immission levels in the water column and sound pulses reach very long distances 3 . Numerical models have been developed and measurements have been performed to assess underwater noise levels during piling [4][5][6][7][8] . Injury and behavioral changes in marine animals have been reported, even at large distances from the piling location [9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Airborne sound propagation over sea during offshore wind farm piling

Renterghem¹,

Botteldooren²,

Dekoninck³

2014

The Journal of the Acoustical Society of America

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Offshore piling for wind farm construction has attracted a lot of attention in recent years due to the extremely high noise emission levels associated with such operations. While underwater noise levels were shown to be harmful for the marine biology, the propagation of airborne piling noise over sea has not been studied in detail before. In this study, detailed numerical calculations have been performed with the Green's Function Parabolic Equation (GFPE) method to estimate noise levels up to a distance of 10 km. Measured noise emission levels during piling of pinpiles for a jacket-foundation wind turbine were assessed and used together with combinations of the sea surface state and idealized vertical sound speed profiles (downwind sound propagation). Effective impedances were found and used to represent non-flat sea surfaces at low-wind sea states 2, 3, and 4. Calculations show that scattering by a rough sea surface, which decreases sound pressure levels, exceeds refractive effects, which increase sound pressure levels under downwind conditions. This suggests that the presence of wind, even when blowing downwind to potential receivers, is beneficial to increase the attenuation of piling sound over the sea. A fully flat sea surface therefore represents a worst-case scenario.

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“…This leads to a difference in the Mach cone apex angle from a solid steel cylinder in the current experiment compared to the thin-walled steel piles in Ref. 1.…”

Section: Theory: Mach Cone Formationmentioning

confidence: 90%

“…Hydrophone arrays have been used to demonstrate Mach cone formation from submerged steel piles (roughly 0.75 m diameter hollow cylinders with a wall thickness of 25.4 mm) when they are driven into the ground for civil construction. 1,2 These impulsive wave fronts are of concern for marine mammals and fish. 3 In the current study, full-field videos of Mach cones in water were obtained using an optical technique called refracto-vibrometry.…”

Section: Introductionmentioning

confidence: 99%

Optical imaging of propagating Mach cones in water using refracto-vibrometry

Huber

2017

The Journal of the Acoustical Society of America

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Refracto-vibrometry was used to optically image propagating Mach cones in water. These Mach cones were produced by ultrasonic longitudinal and shear waves traveling through submerged 12.7 mm diameter metal cylinders. Full-field videos of the propagating wave fronts were obtained using refracto-vibrometry. A laser Doppler vibrometer, directed at a retroreflective surface, sampled time-varying water density at numerous scan points. Wave speeds were determined from the Mach cone apex angles; the measured longitudinal and shear wave speeds in steel (6060 ± 170 m/s and 3310 ± 110 m/s, respectively) and beryllium (12 400 ± 700 m/s and 8100 ± 500 m/s) agreed with published values.

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Underwater Mach wave radiation from impact pile driving: Theory and observation

Cited by 109 publications

References 6 publications

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Bubble curtains attenuate noise from offshore wind farm construction and reduce temporary habitat loss for harbour porpoises

Airborne sound propagation over sea during offshore wind farm piling

Optical imaging of propagating Mach cones in water using refracto-vibrometry

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