Wave radiation from vibratory and impact pile driving in a layered acousto-elastic medium

Wave radiation from vibratory and impact pile driving in a layered acousto-elastic medium

Tsouvalas, A.
Metrikine, A.

Civil Engineering and Geosciences

Structural Engineering

2014-06-30

A steel monopile is the most common foundation type of a wind turbine installed offshore and is driven into place with the help of vibratory or impact hammers. Underwater noise generated during the installation of steel monopiles has recently received considerable attention from international environmental organizations and regulatory bodies in various nations. Collected data regarding underwater noise measurements indicate that pile driving operations, especially when impact hammers are used, can be potentially harmful for the marine ecosystem. In this paper, a linear semi-analytical model is developed for the study of the vibroacoustic behaviour of a coupled pile-soil-water system. The hammer is substituted by an external force applied at the head of the pile. The pile is described by a thin shell theory, whereas both soil and water are modelled as threedimensional continua. The solution is based on the dynamic sub-structuring technique. The total system is divided into two subsystems namely, the shell structure and the soil-fluid medium. The response of each sub-domain is expressed as a summation over a complete set of eigenfunctions. The orthogonality of the shell modes in vacuo and the bi-orthogonality of the acoustoelastic modes is utilized in order to meet the displacement compatibility and the force equilibrium at the interface of the two sub-systems. With the developed model, the wave radiation due to vibratory and impact pile driving is analysed. The influence of soil elasticity and soil stratification on the dynamics of the coupled system is examined. In addition, the energy launched by the hammer into the water and into the soil is investigated for both excitation types in order to highlight the main differences in the generated wave field.

vibroacoustics
pile driving
underwater noise
soil-fluid interface
Scholte waves
dynamics of shells

http://resolver.tudelft.nl/uuid:18650dd0-1cbf-4001-8e1b-3510dd6dadad

University of Porto, Faculty of Engineering, Department of Civil Engineering

978-972-752-165-4

EURODYN 2014: Proceedings of the 9th International Conference on Structural Dynamics, Porto, Portugal, 30 June - 2 July 2014

Institutional Repository

conference paper

(c) 2014 The Author(s)