Publication Abstract

Proceedings - Seventh International Conference & Exhibition on Piling and Deep Foundations, 1998, Vienna, Austria, (DFI)

Jacked Steel Pipe Piles in Underpinning
Pasi Korkeakoski

There are about 400 multi-story buildings founded with wooden piles in the city center of Turku. Because of the groundwater lowering caused by various reasons, pile heads have started to be decay. Then the loss of the structural bearing capacity of old wooden piles might be fatal requiring immediate renovation of existing buildings. In Turku there are two 8-story buildings, which were founded on 350 and 420 wooden piles. The end-bearing wooden piles were so badly decayed, that other pile installation methods than jacking were out of the question. Both buildings were underpinned with about 180 jacked steel pipe piles (139, 7x10). The average length of the piles was 6.5 meter. The piles were jacked from basement through the old foundation. The allowable load of the pile varied from 170kN to 270kN. Jacking of a pile does not effect any vibrations and therefore it does not effect big risk of settlement to the underpinned building. Jacked piles are also possible to install very near of, or even inside to, the bearing structures. That will decrease cost of load transfer structures. Major cost saving will be realized also in demolition and rebuilding cost because the jacking equipment does not need so much space than other pile installation equipment.

 article #370; publication #34 (IC-1998)