Welcome! You are not logged in. [login]

NS-VIP project

Numerical simulation of the installation of vibratory and impact driven piles

This is the website of the NS-VIP project (numerical simulation of the installation of vibratory and impact driven piles) on the vibratory installation of monopiles as an alternative to impact driving. Main aim of the project is the numerical simulation of the vibratory and impact driven pile installation process and subsequent load tests including validation of the simulations with field test results to generalise the findings for locations with different soil conditions and pile diameters. The NS-VIP project is in close cooperation with the VIBRO project in Cuxhaven (Germany) run by RWE Innogy and co-financed by the Carbon Trust Offshore Wind Accelerator (UK).

The NS-VIP project is a collaboration of three industrial partners, i.e. RWE, IHC and Deltares, which work together in a research program initiated and supported by FLOW (Far and Large Offshore Wind). FLOW is a research program consisting of thirteen Dutch companies and research institutes working together on innovation to achieve cost reduction for offshore wind energy. The knowledge and experience with offshore wind farms, located far offshore and in deep water, is quite limited worldwide. FLOW has the aim to increase the reliability of these types of wind farms, to accelerate their development, to lower the riscs, and to significantly contribute to the reduction of costs for offshore wind energy with more than 20%.

More information about the VIBRO project can be found at:
Visit the news site about the VIBRO project

More information about FLOW (Far and Large Offshore Wind) can be found at:
Visit the website of FLOW

More information about NS-VIP? Lars Beuth or Vahid Galavi

Project summary

A consortium of energy utilities, contractors, consultants and universities has initiated a research project (VIBRO project) to investigate the feasibility of using vibratory installation of monopiles to their full installation depth for offshore wind turbines instead of impact driven installation methods. Up to now the certifying bodies require impact driving at least over the last part of the installation due to the uncertainty about the capacity of vibratory installed monopiles. The consortium is performing field tests in a sandpit in Cuxhaven comparing the behaviour of both types of installation methods in particular the lateral capacity and stiffness (eigenfrequency). Cone penetration tests (CPT) are performed before and after installation to assess the installation effects. The soil profile at the test site at Cuxhaven consists of medium dense sand, with silty inclusions overlaying a dense sand layer.

In the VIBRO project this translation is foreseen to be done by comparing CPTs before and after installation. It is expected that the difference in installation effects in layers with different initial cone resistances can be assessed with these CPTs at increasing distance. This is a very useful approach especially for practical applications and codes of practice. However, more insight is required into the effects of the installation methods in sands with different initial densities and the underlying processes.

Current knowledge on the differences between vibrated and impact-driven piles is limited to the axial capacity. It is observed that the ratio between the capacity of vibratory piles versus impact driven piles is less than 1.0 for dense sands and larger than 1.0 for loose sands. Based on this experience it can be concluded that the initial density plays an important role at least for the axial capacity ratio. For lateral capacity and lateral system stiffness this dependency is unknown but will be addressed in the NS-VIP project. Therefore the question arises “How to generalize results of the VIBRO project to sites with other initial densities?”

The aim of the FLOW (Far and Large Offshore Wind) project “NS-VIP” is to develop a numerical modelling tool which combines different existing models into a single tool which can model the installation process of vibratory and impact driven piles and captures the interaction of the pile structure under lateral loading. The model will be validated using the measurement data of the Cuxhaven test site of the VIBRO project. A key deliverable of the NS-VIP project is a database which specifies the resulting lateral capacity depending on the pile diameter, installation method and initial soil density.