For Toyo Corporation Japan and Boskalis Marine Services Netherlands, Dieseko has carried out tests at the Ishikari Bay in Japan for installing and removing anchor piles using our vibration technology. In the long term, a wind farm with floating wind turbines will be built in this location. Piles were driven into the seabed while working 70m subsea. In future these anchors will connect floating wind turbines to the seabed.

The tests have successfully been carried out with our ICE 250NF vibratory hammer equipped with two 350TC hydraulic clamps and driven by an ICE 1600 stage-V powerpack. This single hammer can generate a centrifugal force of 5374kN (548T) at 23Hz.

After the tests Boskalis Marine Services showed their appreciation about working with the Dieseko equipment, crew and project team :“It was great to work with the Dieseko team during the tendering stage, the project preparations as well as during the offshore execution. From day 1 of the project preparations they were clear in communicating and managing expectations, leading to good results for the project, which was under significant time pressure. The Dieseko team expanded as the project evolved, however they’ve kept the same contact person involved from the very start. Because of that there are less surprises during the project execution. The offshore crew was experienced, so they could quickly mobilize the equipment and perform small repair works if necessary. Last but definitely not least, the vibro hammer worked in line with our expectations, leading to a successful offshore campaign.”

In the test, the pile was driven and extracted two times, once to 25m and then to 32m penetration depth. The soil conditions were favorable, weak sandy soil proved no challenge for the 250M. The driving time was well under 10 minutes.

The piling frame was lifted on the level seafloor, the weight and dimensions of the frame were such that there was no need to further anchor it into the seabed. For this foundation type verticality of the pile is also less critical than is the case for Mono Piles that need to ensure that the turbine itself is vertical as well.

The hydraulic hoses were managed by the hose reel, the hammer and reel were operated from a control cabin also supplied by Dieseko, ensuring a good overview over equipment performance.

As you can see in the pictures, the pile was lifted in place with a lifting tool and deposited in the frame. Unfortunately, the 250MU was unavailable, otherwise the client could also have opted for an upending vibratory hammer to perform this function. Dieseko’s upending vibro’s can upend, position and drive piles in an uninterrupted workflow.

The purpose of the tests was to research which method to use for future commercial use for a complete floating wind field. The developer wanted to gain experience with the vibrating method and test the vertical pile capacity. Together Boskalis and Dieseko were able to prove the concept and show that compared to an impact hammering method, working with a (upending) vibratory hammer saves several steps in the process, has faster installation times, increases safety, and reduces underwater noise emissions.

This project proved that the vibrating method should be considered as first choice for the installation of anchor piles for floating wind turbines. Please get in touch with our team to see how we can help you get started!