Keller installed 20 pcs of jet grouting columns with diameters of 1,5 m, 1,6 m and 2,0 m and lengths varying from 3 to 16 meters in clay.
All columns was installed from within the basement and every third column was established in full contact with bedrock 16 meters below the foundations.
The compressive strength requirement of the columns was 8 MPa.

Underpinning of existing building

The project

STØ Entreprenør had the contract with rehabilitating existing buildings and setting up new ones in and around Bernt Ankers gate 6 in Oslo.
Keller was hired to underpin all load bearing walls in one of the existing buildings. The building was underpinned to avoid future settlements.
Every third column under the walls was established down in full contact with bedrock.

The challenge

The challenge in this project was mainly the tight space for the setup of our equipment and the high volume of backflow spoil that had to be treated during production.

The solution

Keller established around 20 pcs of Ø1,5 m, Ø1,6 m and Ø2,0 m jet grouting columns with lengths up to 16 meters for the longest ones that was established in contact with bedrock.
The old foundations were core drilled through to be able to get the center of the columns as close to the walls as possible. The columns were then established down in the clay from the desired level and in good connection with the foundation.
Due to the ground conditions, the columns had to be pre-jetted with water to be able to reach the strength and diameter requirements.
The compressive strength requirement of the columns was 8 MPa.

Project facts

Owner(s)

Olav Thon Eiendomsselskap

Keller business unit(s)

Keller Geoteknikk AS
Keller Grundbau Ges.mbH

Main contractor(s)

STØ Entreprenør AS

Engineer(s)

Project Manager Carl Fredrik Elverhøi