The influence of contact relaxation on underwater noise emission and seabed vibrations due to offshore vibratory pile installation

Abstract

The growing interest in offshore wind leads to an increasing number of wind farms planned to be constructed in the coming years. Installation of these piles often causes high underwater noise levels that harm aquatic life. State-of-the-art models have problems predicting the noise and seabed vibrations from vibratory pile driving. A significant reason for that is the modeling of the sediment and its interaction with the driven pile. In principle, linear vibroacoustic models assume perfect contact between pile and soil, i.e., no pile slip. In this study, this pile-soil interface condition is relaxed, and a slip condition is implemented that allows vertical motion of the pile relative to the soil. First, a model is developed which employs contact spring elements between the pile and the soil, allowing the former to move relative to the latter in the vertical direction. The developed model is then verified against a finite element software. Second, a parametric study is conducted to investigate the effect of the interface conditions on the emitted wave field. The results show that the noise generation mechanism depends strongly on the interface conditions. Third, this study concludes that models developed to predict noise emission from impact pile driving are not directly suitable for vibratory pile driving since the pile-soil interaction becomes essential for noise generation in the latter case.

Ground Vibration Response to Vibratory Sheet Pile Driving and Extraction

“…However, the practical application of this approach is often limited. One critical factor is that driving piles into the ground generates vibrations that may potentially damage surrounding buildings and cause discomfort to nearby residents [4][5][6][7].…”

A multi-physics approach for modelling noise mitigation using an air-bubble curtain in impact pile driving

“…The change in the installation method can significantly alter the characteristics of the radiated wave field (Dahl et al, 2015;Tsouvalas and Metrikine, 2016b;Tsouvalas, 2020). Furthermore, the non-linear conditions at the pile-soil interface can have a substantial impact on the dynamic response of the pile and the wave field in the surrounding medium (Molenkamp et al, 2023;Tsetas et al, 2023).Various noise mitigation systems have been employed to block noise transmission in seawater, e.g., the air-bubble curtain system, the hydro-sound damper system, the noise mitigation screen and resonator-based noise mitigation systems (Lee et al, 2014;Verfuß, 2014;. The efficiency Hydro-Sound-Damper system (HSD) has been examined through measurements and offshore tests as shown in Elmer et al (2012); Bruns et al (2014), which indicates the significant influence of the soil conditions on the sound emsission and the effectiveness of the system.…”