Underwater noise from vibratory pile driving with non-linear frictional pile–soil interaction

Vibratory offshore pile driving offers a potential solution for reducing the underwater noise generated during the installation of foundation piles compared to using impact hammers. Existing noise prediction models are specifically tailored to impact pile driving scenarios. This paper introduces a novel methodology for underwater noise predictions during vibratory pile driving. A non-linear driveability model is utilised to derive realistic non-linear interface friction forces, which are then incorporated into a noise prediction model. The study emphasises the significance of integrating a driveability analysis, revealing substantial differences from traditional models that assume perfect contact between the pile and soil. The authors argue that the proposed model provides more realistic outcomes when considering smooth driving without refusal, in contrast to traditional models designed for impact piling. The results illustrate noticeable deviations in pressure levels and seabed vibrations between the linear and presented methods at the driving frequency and its superharmonics. Furthermore, the research demonstrates that the noise field is highly sensitive to variations in system dynamics and excitation spectrum during driving, using both small- and large-diameter monopiles as examples. This research contributes to developing more effective driving techniques to reduce underwater noise pollution and facilitate sustainable offshore wind turbine installations.