Volker Staal en Funderingen was the first foundation company in the Netherlands to use Rüttel Injection piles.
The piles were used as tension/bearing piles for underwater floor of the construction pit of the new RAI metro station on the Noord-Zuid line. After the construction phase, the piles need to absorb compression forces, but in the construction phase they will be subject to tensile forces.
Initially, the intention was to use in situ vibro combination piles in the pit, but to prevent vibration and noise, it was decided to use RI piles. This kind of pile is frequently used in other countries for construction pits, especially in Germany.
The piles are installed either into an already excavated pit from a temporary mobile bridge construction, a piling pontoon or from ground level.
In this case a bridge was used with a piling rig with a special fixed leader. The leader could be lowered up to 12 metres below water level. Without the need for excess lengt the piles could be installed at final depth without with a vibrator adapted for underwater work.
In the 160 meter long and between 20 en 29 meter wide construction pit for the subwaystation, a total of 550 piles were installed.
Another roughly 400 piles were installed for the adjoining tunnels on both sides of the pit. From ground level and before excavation, approximately 50 piles were vibrated with a fixed leader piling rig.
The associated noise and vibrations were kept to the minimum and, in this sensitive environment, this proved an excellent alternative to pile driving.
The RI piles had a length of up to 24 metres and were equipped with a bulge that created space in the soil during vibrating that was filled in with grout. During vibration, this grout was pumped under pressure through plastic piping along the beam to the point of the pile.