Contactless control of suspended loads for offshore installations: Proof of concept using magnetic interaction

Current offshore wind turbine installation and positioning methods require mechanical equipment attached on the lifted components and human intervention. The present paper studies the development of a contactless motion compensation technique by investigating a magnetically controlled pendulum. The technique involves the interaction of a...

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...

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

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...

Influence of the seabed conditions on the near-and far-field propagation of noise in impact piling

The prediction of underwater noise and the assessment of the influencing factors on noise transmission are significant for the control and mitigation of the noise generated by offshore pile driving. This paper presents a coupled two-step approach for modelling the underwater noise from offshore pile driving, with the focus being placed on...

Installation of large-diameter monopiles: Introducing wave dispersion and non-local soil reaction

During the last decade the offshore wind industry grew ceaselessly and engineering challenges continuously arose in that area. Installation of foundation piles, known as monopiles, is one of the most critical phases in the construction of offshore wind farms. Prior to installation a drivability study is performed, by means of pile driving...

Study of the sound escape with the use of an air bubble curtain in offshore pile driving

Underwater noise pollution generated by offshore pile driving has raised serious concerns over the ecological impact on marine life. To comply with the strict governmental regulations on the threshold levels of underwater noise, bubble curtains are usually applied in practice. This paper examines the effectiveness of an air bubble curtain...

A coupled modelling approach for the fast computation of underwater noise radiation from offshore pile driving

This paper presents a computationally efficient modelling approach for the prediction of underwater noise radiation from offshore pile driving. A near-source module is adopted to capture the interaction between the pile, fluid and soil, which is based on a previously developed semi-analytical vibro-acoustic model. This module primarily aims...

Underwater Noise Generated By Offshore Pile Driving: A Pile-Soil-Water Vibroacoustic Model Based On A Mode Matching Method

In this paper, a pile-water-soil model is developed for the prediction of sound generated due to impact piling. The complete model consists of two modules: i) a near-source module aiming at the accurate description of the pile-water-soil interaction together with the sound generation and propagation in the vicinity of the pile; and ii) a far...

Dynamic soil stiffness for foundation piles: Capturing 3D continuum effects in an effective, non-local 1D model

A method is presented to accurately capture the 3D interaction phenomena of a foundation pile embedded in soil, in a computationally efficient non-local 1D model. It is shown how to extract the global stiffness kernels from simulations with the 3D inhomogeneous continuum, and implement them in a 1D non-local Winkler-type model that can...

Effective soil-stiffness validation: Shaker excitation of an in-situ monopile foundation

In an attempt to decrease the modelling uncertainty associated with the soil-structure interaction of large-diameter monopile foundations, a hydraulic shaker was used to excite a real-sized, in-situ monopile foundation in stiff, sandy soil in a near-shore wind farm. The response in terms of natural frequency and damping of a pile-only system...

Initial results of a study into the estimation of the development of frequency lock-in for offshore structures subjected to ice loading

Ice-induced vibrations have to be considered in design of vertically sided offshore structures subjected to loading by sea ice, such as offshore wind turbines and oil- and gas platforms. The interaction between ice and structure may result in high global peak loads and the occurring structural vibrations can contribute significantly to the...

Effective stiffness method for rigid monopile foundations of offshore wind turbines and in-situ validation

It is widely accepted that the initial stiffness derived with the p-y methodology as prescribed by the American Petroleum Institute does not capture the true small-strain stiffness for rigidly behaving piles. We present an alternative method, capturing the 3D effects in the soil-pile interaction, in which the soil is characterized with in-situ...

The Effect of Stress Wave Dispersion on the Drivability Analysis of Large-Diameter Monopiles

Due to the increasing need for energy from renewable resources, a large number of offshore wind farms are planned to be constructed in the near future. Despite the plethora of available foundation concepts for offshore wind turbines, the monopile foundation is the most widely adopted concept in practice. To predict the installation process for a...

A method for identification of an effective Winkler foundation for largediameter offshore wind turbine support structures based on in-situ measured small-strain soil response and 3D modelling

A procedure is presented for the derivation of an effective small-strain soil stiffness governing the soil– structure interaction of large-diameter monopiles. As a first step, geophysical measurements are used to estimate the depth-dependent shear modulus G of the soil stratum. The second step is to use this modulus and an estimated Poisson’s...

Structure-Borne Wave Radiation by Impact and Vibratory Piling in Offshore Installations: From Sound Prediction to Auditory Damage

Anthropogenic noise emission in the marine environment is a key issue nowadays and has drawn the attention of regulatory bodies in various nations. In particular, the noise generated during the installation of foundation piles for the offshore wind industry is considered to be harmful for aquatic species. A reliable prediction of the underwater...

Assessing the small-strain soil stiffness for offshore wind turbines based on in situ seismic measurements

In this contribution, in situ seismic measurements are used to derive the small-strain shear modulus of soil as input for two soil-structure interaction (SSI) models to assess the initial soil stiffness for offshore wind turbine foundations. This stiffness has a defining influence on the first natural frequency of offshore wind turbines (OWTs),...