UACE2017 Proceedings: Prognosis of underwater pile driving noise for submerged skirt piles of jacket structures

• Session:
  Underwater Noise - Modelling and Measurements
• Paper:
  Prognosis of underwater pile driving noise for submerged skirt piles of jacket structures
• Author(s):
  Stephan Lippert, Marco Huisman, Marcel Ruhnau, Otto Von Estorff, Kees Van Zandwijk
• Abstract:
  Offshore pile driving noise has gathered an increasing importance during the last decade. Especially the huge number of monopiles, which are typically used as foundations for the large wind turbines, contribute to the noise emission into the water column. Beside monopiles, also jacket structures can be found in wind farms as foundations for e.g. transformer stations or service platforms. Jacket structures are further used at deeper locations, e.g. for oil and gas platforms.\nA general difference between the monopiles of wind turbines and the skirt piles that are often applied for fastening jacket structures is the identification of the critical scenario for underwater noise prognosis. For monopiles, the highest noise levels are in general observed at the final embedment depth, when the highest hammer energy is applied. At the end of piling, the monopiles still have a certain stick-out above the sea surface. In contrast, the top of skirt piles is submerged at final penetration depth. Thereby, the increasing hammer energy with penetration depth and the simultaneously decreasing free pile length in the water column make it hard to define the critical scenario from an acoustical point of view.\nIn this contribution, the measured underwater noise levels of four submerged skirt piles for a transformer station are compared to the levels that have been predicted by a comprehensive FE modelling approach before the offshore installation started. Thereby, the FE model included a careful derivation of the excitation force by the hammer as well as a detailed layered soil profile and noise mitigation measures. Based on the results from measurement and simulation, it is possible to gain a valuable insight to the development of underwater noise with increasing embedment of submerged skirt piles.
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Contact details

• Contact person:
  Dr Stephan Lippert
• e-mail:
  
• Affiliation:
  Hamburg University of Technology
• Country:
  Germany