Underwater Sound Modelling and Sound Mapping in Vibratory Pile Driving

The installation of foundation piles for offshore wind turbines using traditional hydraulic impact hammers raises concerns about the impact of underwater noise on marine life. To address this issue, the offshore wind industry investigates the use of alternative driving techniques, such as vibratory pile installation, to reduce sound levels and expedite installation. This paper discusses a method for modelling underwater sound generated in vibratory piling and presents sound maps of broadband sound levels. The complete model comprises sub-models, including the generation of the source field and the propagation of the sound in range-dependent shallow water environments. The sound source model utilizes a non-linear three-dimensional pile–soil-water modelling framework tailored for vibratory pile installation in layered media, capturing the coupled pile-soil-water interaction at the source. The sound propagation model employed for generating sound maps is a normal mode model, designed to simulate propagation loss in range-dependent acousto-elastic half-spaces of varying bathymetry. The paper concludes with the theoretical case study of underwater noise emission from vibratory pile installation in the North Sea. Numerical simulations with the adopted modelling framework can be used by marine biologists to assess the environmental impact of underwater sound on marine species.