Results of a project testing vibratory method of pile driving have shown the method generates less noise and is up to ten times faster, compared to the impact hammering.
The project, carried out by RWE Innogy, Bilfinger Offshore, DONG Energy, EnBW, E.ON and Vattenfall under the Carbon Trust Offshore Wind Accelerator programme, involved a comparison of the conventional method of impact hammering with the vibration of steel piles in a test environment on land.
The test on land have shown that the vibratory method generates lower peak noise emissions and is up to ten times faster. Continuously present noise emissions will need to be determined on a project specific basis. The lateral bearing capacity of large diameter piles has been measured allowing an initial methodology for the prediction of vibrated pile bearing capacity to be developed, according to the companies behind the project.
Noise emissions will need to be investigated on a project specific basis to determine if the significantly reduced, but continuously present noise will have an impact on the environment under water, RWE said in a press release issued today.
In the course of the tests, it was discovered that the vibratory installation method has a major impact on the lateral load-bearing capacity of the piles. If during the installation process various parameters, such as vibratory frequencies or pile design, are controlled, similar lateral load-bearing capacities to hammered piles could be achieved.
The consortium devised a methodology that made it possible to pre-determine the load-bearing capacity of vibrated piles. RWE Innogy now plans to build on these tests and launch an additional subproject intended to investigate ways of optimising the installation methodology itself.
The findings of the research project have been made available to all project partners and the Carbon Trust Offshore Wind Accelerator.