Gentle Driving of Pile electric shaker (eGDP)

WHY

The GROW consortium is advancing the Gentle Driving of Piles (GDP) technology, an installation method designed to make offshore monopile installation both more efficient and more environmentally responsible. The technique applies a combination of a low‑frequency vertical vibration and a high‑frequency torsional vibration to the pile. This approach is considered “gentle” because it is intended to reduce radial expansions of the pile and, in that way, to significantly lower noise emissions, which are known to affect marine life. The method has already been successfully tested in sandy soils (GDP1.0) and clay (GDP1.2), and further insights have been gained through the SIMOX and VINEX projects. For instance, it was proven that GDP-driven piles have superior lateral bearing capacity compared to the piles driven by conventional vibro-hammers.

Two lab-scale and three onshore-size GDP shaker prototypes have been developed and tested to date. The first onshore prororype was able to install piles with diameters of just under 1 metre in both sand and clay, demonstrating good driveability and lateral capacity, but its energy consumption was too high. This inefficiency stemmed from the vibration actuators, which were originally designed for low‑frequency applications and were unable to deliver the required high‑frequency performance. The second prototype, developed within SIMOX, could drive piles with diameters slightly over two metres and incorporated several engineering improvements. However, it still fell short of expectations: torsional frequencies remained too low, the necessary balance between vertical and torsional power was not achieved, and overheating and other technical issues caused interruptions. These shortcomings highlighted the need for independent control of vibration parameters and more advanced engineering solutions.

The third prototype was tested within the GDP2.0 project for the same soil and pile as the previous one. This prototype had linear hydraulic actuators and its control algorithm was based on adjusting accordingly to the pile response. Within the GDP2.0 project, a larger shaker is now being developed based on multiple synchronised units, each capable of generating either low‑frequency vertical motion or high‑frequency torsion. The aforementioned tests on a 2.2‑metre‑diameter pile have shown promising performance, but they also indicated that linear hydraulic actuation may not scale effectively. For this reason, the next step is to introduce an electric actuation system, which eliminates the inefficiency and other risks associated with a hydraulic fluid, reduces the environmental impact, and simplifies offshore handling by replacing complex hydraulic hose bundles with a single power cable.

WHAT

The new eDGP project will carry out a dedicated onshore test campaign to evaluate a newly developed electric GDP shaker, which is expected to outperform the existing hydraulic system. The test will take place at the Ruijgoordweg site in Amsterdam, a location previously used for SIMOX and GDP2.0, allowing immediate access without the need for new environmental permits and enabling direct comparison with the earlier results. Existing geotechnical data and an already instrumented 2.2‑metre‑diameter, 27‑metre‑long test pile will be reused, although structural reinforcements may be required due to the higher weight and clamping forces of the electric system.

During the campaign, the team will drive the pile through sand, clay and peat layers to study pile–soil interaction across the full penetration depth, with particular attention to clay behaviour, which has not yet been thoroughly investigated. The project will test the electric shaker’s phase‑control system, collect extensive measurement data at different frequencies and amplitudes, and assess three different pile‑tip profiles. Additional activities include soil‑vibration measurements using geophones to verify noise‑reduction claims, testing polyurethane (PU) padding between tool and pile, performing extraction tests with varying settlement times, and organising a demonstration for the eGDP partners. All team members and subcontractors already have experience at this site, which reduces the operational risks.

EXPECTED RESULTS

The project is expected to generate clear, practical insights into the controllability, power transfer, and overall behaviour of the electric prototype, including how it responds to control inputs and how the pile responds as it moves through different soil layers. With the substantially higher installed power, the system should be capable of driving the pile much deeper than in earlier campaigns, enabling a full driveability assessment for the first time. The measurements collected during the test will be used to validate and further develop mathematical models describing pile-soil interaction, frequency‑response control, driveability, fatigue behaviour, soil vibration and underwater noise. Strengthening these models will enhance the scientific foundation of the GDP concept and provide the evidence needed to determine whether the electric system should be scaled up into a 4‑metre offshore‑ready tool. In doing so, the project will contribute to both industrial research and the broader fundamental understanding of vibratory pile‑installation processes.