Innovative foundation method for urban area

In built-up areas, driving foundation piles is often not an option. Vibrations and noise pollution are out of the question there. Therefore, the piles here are usually drilled. Two years ago, a new foundation method was introduced, the pressing of precast concrete foundation piles. An increasing number of projects are now being founded with this.

Nowadays, much construction takes place in urban areas. Contractors are faced with the government's requirement to limit nuisance, including when installing the foundation. Piling prefabricated foundation piles is not possible here. The only suitable method is to drill or screw foundation piles. But in doing so, the contractor often has no control over the quality. "That is usually difficult to assess afterwards," says Tahl Tekofsky, technical-commercial consultant at Drukpaal.nl. "The sometimes weak Dutch soil and the presence of groundwater can affect the pouring of a pile. In addition, with most drilling methods there is a risk for employees of contact with possible contaminated soil."

Printing method
To prevent this, Drukpaal.nl, part of the IJB Group, introduced a simple but innovative method in the Netherlands two years ago. Here, high-quality prefabricated piles are pushed into the ground by a hydraulically driven foundation machine. Usually square piles with diameters of 290, 320 or 250 mm and of various lengths. This is done completely quietly and vibration-free. Also, this method is 100% soil displacement and without contact risk with contaminated soil. Pressing is not only better quality, with 15 to 20 piles per day it is also faster and price competitive compared to drilling. The pressure method has been a reliable solution in Asia for decades. Tekofsky therefore considers it an excellent alternative to drilling or screwing. 

New foundation method, pressing precast concrete foundation piles.

Special hydraulic foundation machine
A specially developed hydraulic foundation machine is used to press the precast foundation piles into the ground. This contains a pressure unit that grips the concrete pile with clamps and then pushes it into the ground in strokes of about two meters. From three meters above ground level, the machine can no longer grip the pile. To still get the pile to the correct depth, a pusher is placed on top that brings the pile up to the intended level. During pressing, each pile is test loaded and a record is made. Afterwards, Drukpaal.nl reports the measured compression force against the depth for each pile. In this way the resistance, and thus also the allowable load, is measured. You can then be sure that each pile can deliver the required load.

St. Sebastiaansbrug Delft
Tekofsky: "Until now, we have worked mostly for larger apartment complexes and utility buildings. Now we are working for the first time on an infrastructure project, the new Sint Sebastiaansbrug in downtown Delft. Our method was chosen because it is low-noise and low-vibration, and financially interesting." A pile foundation is required for the ramps on the north and south sides of the bridge. There will be large masses of soil on top, rising slowly from 4 to 8 meters to the highest point of the bridge. Streetcar tracks, bicycle and pedestrian paths and an asphalt road will be built on top of this. The ramps will therefore be founded on a pile mattress of 400 piles. "Here we are going to press 21 to 22 m long square piles with a diameter of 290 mm. A project that literally and figuratively has quite a lot going for it!" said Tekofsky.