Installation of pile foundations by vibratory-driving - VIBRO-Project

Leitung: Prof. Dr.-Ing. Martin Achmus
Bearbeiter: Dipl.-Ing. Kirill Schmoor
Laufzeit: abgeschlossen    

Fig. 1: Comparison of the axial bearing capacity of vibrated and impact-driven piles (from Lammerz 2008).

Compared to the usual installation technique, namely installation by impact- driving, the vibratory-driving represents an alternative way for the installation of piles. Thereby the pile is subjected to vertical vibrations which were transferred to the surrounding subsoil. Due to this the normal stress of the grains decreases which also lead to decrease of the shear resistance. By applying static surcharge force the pile can be penetrated into the subsoil.

In comparison to the conventional installation technique by impact-driving less noise emission is produced. Also the installation time can usually be reduced.

Regarding the axial bearing capacity of vibrated piles several researches can be found. In general is can be observed that the axial capacity of vibrated piles is less compared to impact-driven piles. However, the reduction or the decrease in axial bearing capacity depends on the subsoil consitions (type of soil, relative density) and the parameters of the installation (frequency, static surcharge, excitation force, rate of penetration).

Within the project “VIBRO” the lateral bearing capacity of vibrated piles was investigated.  Therefore 3 lateral pile load tests with a vibrated and an impact-driven pile were conducted by a consortium of several companies like RWE Innogy, DONG Energy, EnBW, E.ON and Vattenfall  within the Carbon Trust Offshore Wind Accelerator program. The pile diameters were 4,3m where the pile lengths were 21m. The test campaign was executed in Cuxhaven. For more information the reader is referred to the official press release  and the video  by RWE Innogy.