• Keller installed an interlocking pile wall consisting of 139 pcs Ø406 casings and 11 pcs of drilled strand anchors to support the pile wall.
• Steel Core Piles Ø150mm were drilled as the foundation for a future bridge that will be used to transport materials from the main tunnel.
• Deep Soil Mixing was used to secure an area with sensitive clay / quick clay.
The project
Keller has been contracted by HAB Constructions to execute an interlocked pile wall in conjunction to a side tunnel for the new Fornebubanen.
The works will prepare for access to transport materials out from the main tunnel during the construction period. The works were finished in a 3 weeks period.
The challenge
The challenge in this project was mainly all the drilling in hard bedrock with large casing diameter in addition to challenging injection works.
The solution
The solution in the project was to mobilize our Comacchio MC40 drilling rig to secure a good progress.
The casings were installed in lengths of about 8-10m and all casings were installed minimum 2 m into bedrock with a special drilling bit adapted to hard bedrock. All casings were installed with interlock and were injected through an injection channel in the interlock.
After the injection, all casings were filled with concrete. The steel core piles were installed with Ø219 casings and Ø150 mm cores with both compression and tension piles. In addition, 11 pcs of strand anchors were installed to support the pile wall.
To secure an area with sensitive clay/quick clay, Dry Deep Soil Mixing was also used.