An underground reservoir was to be constructed at Doha in Qatar. Simsima lime stone is present at the bottom. When the reservoir is empty, there will be uplift at the bottom but this will change to downward load when it is full. The rock at the bottom had high bearing capacity to resist downward load. But uplift had to be resisted by piles or anchors. The reservoir has a size of 120mx80m. Shrinkage and creep of concrete coupled with thermal contraction imposed a horizontal movement of 26mm on the extreme piles. So, piles have to accommodate this as well. This unique situation needed a unique solution. The solution was to provide piles with flexible high tensile strands to take tension. An annular space near the head of the pile would facilitate horizontal movement as well. Compression load was directly passed on to the raft bearing on rock.
Subjects: Tension piles, high tensile strands, simsima lime stone, horizontal movement
Author: Dr. Ir Chandramohan P. V., President (technical) and Ravi Kishore, General Manager
Publisher: DFI