The client, Berlin-based IB Vogt, is a developer of renewable energy projects with a focus on photovoltaic schemes worldwide.
The photovoltaic panels are designed to cover a very large, 3m-deep water retention basin. They are placed on lattice beams, and then mounted on the pile head in a grid of 6m by 12m. Poor ground conditions have made deep foundations a necessity and the decision was taken to use Centrum precast piles. The precast piles serve as a base for mounting, a 3m-high standing column and as the deep foundation element.
Before starting installation on site, some product development and additional soil investigations were carried out due to high demands for accuracy of the pile installation. They had to be installed at +/- 50mm horizontally and +/- 30mmvertically.
In the pile head, a M42 threaded sleeve - provided through Pfeifer Bautechnik - is centrally positioned to allow quick assembly of the beam connection. The transition piece between pile head and beam provides the necessary tolerance. Additional cone penetration tests were carried out by Fugro to give certainty about pile ‘drivability’ and the ability to reach the planned pile toe depths and secure the vertical tolerance.
Aarsleff said that the team on site, consisting of the project manager Rainer Scharrel and his rig operators and banksmen, met all expectations with regards to accuracy, quality, speed and health and safety standards. The two Junttan rigs – a PMx22 with a SHK5 hammer and PM25 with a HHK7 hammer – were chosen as being ideally suited for the task.
Peter Wardinghus, managing director at Aarsleff Grundbau, said: “Our experience with this project has been very positive, especially the very partner-like and professional cooperation with the client and his consultants. The suitability of the pile system has received a strong confirmation and more opportunities to plan, design and deliver smart ground engineering solutions within the renewable energy segment are in sight.”