Underwater Noise in Offshore Impact Piling Including Pile-Soil Contact Relaxation

As the trend shifts toward the installation of larger foundation piles for offshore wind farms, which are associated with lower frequency excitations, accurately predicting the resulting sound and vibrations requires a precise characterization of soil behaviour and pile-soil interaction. In addition to noise emissions caused by pile installation, substrate-borne vibrations are particularly perceptible to various marine biota. Both seabed vibrations and underwater noise raise concerns about ecological impacts, emphasizing the need for predictive models that accurately represent the interactions between pile, soil, and seawater. This paper examines the effects of the inclusion of the pile-soil contact mechanism during impact pile driving both in the underwater soundand the seabed vibrations. The pile-soil mechanism condition is modelled by the introduction of linear springs at thepile-soil interface allowing for relative displacement to develop between the soil and the pile. A case study is conducted to explore the implications of the contact mechanism, focusing on the two key outputs: the noise levels in thesurrounding fluid and particle motion within the substrate. Sensitivity analysis is performed to evaluate how variations in contact conditions during impact piling influence these critical metrics.