The background for the assignment from the University of Oslo (UiO) was that the building had been settling, and there was concern that further settlement could cause irreparable damage. Settlement measurements were being carried out quarterly to monitor the progression.
As part of the investigation into possible underpinning solutions, available historical materials were reviewed to understand how the building had originally been founded. Detailed drawings and descriptions from the construction period (1898–1904) showed that the building was supported by approximately 2,300 wooden piles, each about 10 meters long, embedded in a 1.2-meter-thick foundation slab. A trial excavation conducted in 2020 uncovered the slab and confirmed that the wooden piles were still surrounded by groundwater, which is essential since exposure above the groundwater level could lead to rot and reduced bearing capacity.
The proposed solution in the report involved steel core piles to bedrock, connected with concrete beams (cross-section 0.9 m × 0.9 m) slotted into the existing foundation slab. All piling work was planned to be carried out within the basement to avoid interference with the existing timber piles and the technical room located outside the building.
By placing new beams within the existing slab, the basement space could be largely preserved. Other alternatives are considered, and recommendations for future phases were provided.
Alternative solutions for refounding the building.