RD piles in soft and quick clay on Kløfta, North of Oslo

SSAB delivered 1000 m RD220/12.5 piles in lengths of 6 and 12 m to Entreprenørservice AS and their project on Kløfta – 6 km north of Oslo. The project is an extension in connection to an existing warehouse. The size of the extension will be 46 x 94 m and 22 m high and act as an automatic storage for paint cans. The robotics and the weight of the cans is the dimensioning factor for the foundation work in the project. Risk for damages on existing building during the piling work was high.

The ground consists of a 3 m layer of dry clay crust, 9-17 m of soft to medium clay and a bottom layer of quick clay down to bedrock at 20 to 37 m. There was also a risk for the bedrock to be inclined. Groundwater table was approx. 3 m below the terrain. The very characteristic “Romeriks mjele” was also located at the site. This is a silt layer bright in color that were deposited after a huge flood event during the last ice age 9 100 years ago.

RD piles with lengths from 19 to 41 m were installed in the areas where most of weight should be placed. They were also used closest to the existing building. Main reasons why Entreprenørservice AS chose the RD pile solution from SSAB was to avoid disturbance and damages to the neighboring building. The piles were also designed to withstand earthquake forces and to absorb the tensile forces. RD piles are installed by drilling and are especially suitable for difficult ground and environmental conditions. Steel grade of the piles was S550J2H. Most of the piles were delivered as ready-made pile elements with threaded heads.

The piling contractor - Entreprenørservice AS had an unusual drilling project when drilling 12 m pile elements very close to an existing building. Dag Haug from Entreprenørservice AS explains that it is possible to drill up to 0.6 m from an existing wall. JM Norge Entrepenør is the main contractor for the project.