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This
project was to perform remedial works to seize the active settlement
of raft foundation of Desalination units at Al-Jubail, Saudi Arabia.
The channels carrying water around and below raft foundation were
severely damaged and cracked making an easy access to the flowing
water, which led to erosion of subsurface soil causing the raft
foundation to settle. This problem has caused the Desalination unit
non-operational and affected the production and supply of water. The
space above the raft foundation is very congested and very difficult
for normal civil works to be carried out, so an efficient solution
of mini piling the raft foundation using small specialized compact
equipment was undertaken.
The subsurface geotechnical conditions below the raft foundation
were investigated and a steel cased pile of 150mm diameter with an
estimated working load capacity of 13 tons was chosen for a pile
test, to record the load/settlement characteristics of pile and to
check its load carrying capacity. Due to very loose sand below the
raft, the pile had to be a frictional pile and the depth of pile had
to be around 10m to rest its end on a dense/firm supporting strata.
After detailed study of the situation, having performed load
calculations, and a pile test, a final design of mini piling system
of 308 piles for each desalination unit was executed.
For closing the gap already present between the evaporator base and
the columns, neoprene elastomeric bearing pads were placed so as to
ensure uniform distribution of loads and smooth functioning of unit.
For installation of these bearing pads, the beams of the evaporator
base were lifted using our steel frame and hydraulic jacks. After
lifting the structure, the bearing pads of appropriate thickness
were placed at these locations and slowly the beams of the
evaporator base were lowered. This process was repeated till all the
existing gaps were filled.
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