Experiences with Hydro-Sound Measurements during Pile Driving - Past, Today and Future- Dr. M. A. Bellmann, P. Remmers, H. Holst, S. Gündert und M. Müller Itap GmbH Institute of technical and applied physics Oldenburg, Germany Bellmann et al. Seite 1
1. Motivations Experiences with Pile-Driving Activities 2000-2010 FINO 3 R&D Alpha ventus R&D UFOplan (round robin) R&D Test piles OWF BALTIC StUK3 Schall 1/2/3.. R&D Several OWFs in Europe mostly without Noise Mitigation Systems (NMS) Past 2011 2013 ESRA (round robin) R&D OFT1 R&D OWF BW II R&D + StUK3 OWF Meerwind SO StUK3 OWF NSO StUK3 HSD OWF LA R&D BORA OMK I R&D OWF Global Tech I R&D + StUK3 OWF DanTysk StUK3 OWF BALTIC II StUK3 OWF Riffgat StUK3 Several substations + test piles StUK3 Today Bellmann et al. Seite 2
2. The Past Common Practice / Influencing Factors Most pile-driving activities without Noise Mitigation Systems NMS only used in R&D projects Pile diameter < 4 m Influencing factors on hydro sound (without NMS): Pile diameter (ø) Blow energy Water (not between 20m and 40m) / penetration depth Bellmann et al. Seite 3
Level /db re 1 µpa 1. Motivation 2. Past 3. Today 4. Summary 5. Outlook (Future) 2. The Past SEL vs. Blow Energy / Penetration Depth Penetration / m Soft-start Blow Energy / kj Time Bellmann et al. Seite 4
Level /db re 1 µpa 1. Motivation 2. Past 3. Today 4. Summary 5. Outlook (Future) 2. The Past Hydro-Sound vs. Pile Diameter (measurements) 220 210 200 190 180 170 160 150 140 Measured SEL 50 @ 750m Measured L Peak @ 750m Mean regression Mean regression +5dB Mean regression -5dB 130 0 1 2 3 4 5 6 7 8 Diameter /m Difference SEL 5 SEL 50 2,5 db Bellmann et al. Seite 5
3. Today Common Practice / Influencing Factors NMS are requested for all noisy activities Pile diameter up to 6 m Influencing factors on hydro sound: Pile diameter(ø) Blow energy Water (not between 20m and 40m) / penetration depth Methode: pre- or post-piling Sediment layer ( ground coupling ) Other factors? Are these parameters indenpent from each other? Bellmann et al. Seite 6
Level / db re 1 µpa 1. Motivation 2. Past 3. Today 4. Summary 5. Outlook (Future) 3. Today SEL vs. Hammer Type / Blow Energy / Pile Diameter 10 db Monopile ø 6,0 m Tripod ø 2,5 m Monopile ø 6,0 m Jacket ø 2,4 m Monopile ø 6,0 m Jacket ø 2,0 m Spectral distribution of reference will have significant influence on noise reduction by using NMS 20 40 80 160 315 630 1250 2500 5000 10000 20000 Center Frequency / Hz Bellmann et al. Seite 7
Noise Mitigation System (metal) tube with foam Firehose System (Menck) BeKa-Shell (Weyres) Noise Mitigation Screen (IHC) 3. Today Overview: Noise Mitigation Systems Big Bubble Curtain BBC (HTL, Weyres) unguided Little Bubble Curtain ulbc (HTL) guided Little Bubble Curtain glbc (Weyres) Small Bubble Curtain - SBC (Menck) double BBC (HTL, Weyres) Hydro Sound Damper (HSD) Kofferdam (Thomsen) 1. Motivation 2. Past 3. Today 4. Summary 5. Outlook (Future) Tested variations air flow (yes/no) internal bubble curtain, air flow internal bubble curtain, air flow hose configuration, air flow, hose length, air flow air flow hose configuration, air flow distance between two hoses, distance of rings, HSD material Bellmann et al. Seite 8
3. Today Test Locations for a BBC under Offshore-Conditions FINO 3 1 Pile Messmast NordseeOst 1 Pile OWF Borkum West II 38 Tripods OWF Meerwind SüdOst up to 80 Monopiles + substation (Jacket) OWF Nordsee Ost up to 48 WEA Jackets + substation (Jacket) OWF DanTysk up to 80 Monopiles OWF Global Tech I up to 80 WEA Tripods OWF BALTIC II (Baltic Sea) up to 80 Monopiles/Jackets Substation several Jackets 2 BBC manufactors currently available on market > 15 BBC system configurations are tested! Bellmann et al. Seite 9
3. Today Tested BBC System Configurations Single, Double, Triple Big Bubble Curtain (BBC, DBBC, TBBC) BBC hose (ø): 75-100 mm Total hose length (total): 1.000 m < L < 3.000 m single BBC length: 400 m < L < 1.000 m Hole size (ø): 1-2 mm Hole distance: 20-60 cm BBC radius: 70-160 m Air flow: 0,075-0,43 m 3 /(min*m) BBC air feed-in: one- / double-sided Water depth: 20-40 m Ballast: Ballast chain inside/outside BBC laying: pre- / post-laying with / without pressure Bellmann et al. Seite 10
Influencing parameters 3. Today BBC: Influencing Factors on Noise Reduction Hose configuration (hole size + distance, ballast, diameter) Distance between two BBC hoses (for Double / Triple BBC) used air flow (Diameter - ø 4 )! Probably influencing parameters Water depth / pressure of air flow (?) Ground coupling (?) Bathemetry, weather conditions (wave height, wind, ) (?) Partly technical problems or not optimised system configuration reduce noise reduction! Currently running research project: technical optimisation and enhancement of noise reduction of the BBC Bellmann et al. Seite 11
3. Today Insertion Loss of tested NMS (1/2) Optimal system configuration for each NMS No. Noise Mitigation System ΔSEL [db] 1 Single Big Bubble Curtain - BBC (> 0,3 m 3 /(min*m), small holes and distance, ballast outside hose) 2 Double Big Bubble Curtain - DBBC (> 0,3 m 3 /(min*m), ballast outside hose, two separated BBC) 3 Small Bubble Curtain SBC (ΔSEL depends significantly on used air) 4 Hydro Sound Damper (ΔSEL depends significantly on used no./size of elements) 5 Noise Mitigation Screen NMS (ΔSEL depends significantly on distance between tubes) 6 Kofferdam (ΔSEL depends significantly on function of sealing lip) 10 13 15 14 17 18 (5) 14 8 13 5-7 (Riffgat: 10 18?) problems < 10 no problems 20 Insertion Loss: ΔL peak ΔSEL Bellmann et al. Seite 12
3. Today Insertion Loss of tested NMS (2/2) SEL reduction (1/3 octave) / db re 1 m Pa Highest energy input from Pile Driving Center Frequency / Hz Increasing sensitivity of marine mammels Bellmann et al. Seite 13
4. Summary (1/2) Past (and Today) Pile-driving noise depends on: Pile diameter Blow energy Water depth (no influence LAT -20 m -50 m) pre-/post-piling (partly) distance Sediment layer ( ground coupling ) Probably used hammer type (?) No NMS or NMS only tested on single foundations (R&D) Bellmann et al. Seite 14
4. Summary (2/2) Today NMS are needed for all pile-driving activities Several NMS are available (prototypes) Only few NMS applicable during normal construction process Only some influencing factors for noise reduction of several NMS are well known Noise reduction (in best available system configuration ): with one NMS: ΔSEL 10 db; ΔL Peak 10 db State-of-the-art for NMS is currently not available Pile Diameter up to 6.0 m will need more than one NMS/methode to fulfil the German Limiting Values! Bellmann et al. Seite 15
5. Outlook Future Combinations of NMS/methode for large foundation structures (e.g. Monopiles with ø 6 m,. ) to fulfil the German limiting values (?) State-of-the-Art regarding NMS available within the next months (?) E.g.: List of currently optimised system configurations for each tested NMS included measured noise reduction (?) Other foundation installation methods needed (?) Bellmann et al. Seite 16
Quelle: ESRa Kunte Quelle: Trianel Lang Quelle: ESRa Kunte Thanks to: BMU / PTJ (government) all OWF operators all NMS manufactures all companies during construction process my colleagues Quelle: ESRa Kunte Quelle: ESRa Kunte Quelle: Trianel Berlin, Lang Oct. 30 th /31 st 2013 Bellmann et al. Seite 17 Quelle: Trianel Quelle: Lang ESRa Kunte
Thank you for your attention! Source: F. Wilke, RWE Bellmann et al. Seite 18
3. Today SEL vs. Blow Energy / Ground Coupling Ground Coupling + Blow Energy @ OWF London Array F05 F04 Bellmann et al. Seite 19