Karlatornet (Sweden)
Engineering excellence below ground
More than 12,000 m³ of high strength concrete have been added to the 58 cast-in-place concrete piles that will carry the new Karlatornet skyscraper in Gothenburg. To master the challenging ground conditions, new smart solutions were required for the foundation building.
When finished in 2021, Karlatornet will be 245 meters high and contain 73 floors for homes, offices and hotels. So far, however, the building has not reached ground level. On the other hand, it stretches about 70 meters below ground level – through a 40–50 meter thick layer of clay, about ten meters of cohesionless soil (gravel, stones and blocks) and up to seven meters into the local bohus granite, where the foundation is anchored. The distance down to the mountain, which also leans, was a challenge. Drilled shaft piers as a foundation method is unusual in construction in Sweden, but will be used considerably more in the future as more and more tall houses are built on unstable land.
"We have worked with similar technology in Denmark earlier, though in much smaller dimensions. Here in Gothenburg, each cast-in-place pile measures two meters in diameter and is capable of carrying a load of around 4,500 tonnes individually, "said Kim Bräuner Rasmussen, Project Manager at Construction Contractor Aarsleff, who performed the foundation work on behalf of construction company Serneke.
Karlatornet will be the tallest building in the Nordic region and is part of Gothenburg's new district Karlastaden, which will consist of eight blocks of housing, offices, commerce and service. The area is being developed by Karlastaden Utveckling AB, which is owned by half of Serneke and half of the NREP (Nordic Real Estate Group).
Close collaboration between architects, contractors and material suppliers has been crucial for the successful completion of the Karlatorn's in-depth foundation. With all 58 cast-in-place pile in place, the work continues to make the bottom plate in early 2019 possible. It should be placed eight meters below ground level and be close to four meters thick.
