A Self-Learning Manual - Institution of Engineers Mauritius

A Self-Learning Manual
Mastering Different Fields of Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU
bearing capacity than open-ended piles as close-ended piles prevent soil
from entering the piles and force them around the pile tip leading to a
higher stress state in this region.
7. Why are sleeves often installed inside the lower part of open-ended
driven piles? (MP1)
In marine piles, open-ended piles are more often used than close-ended
piles to enhance longer length of piles installed. This is essential to provide
better lateral resistance against berthing loads and other lateral loads in
marine structures.
To enhance longer length of driven piles installed, sleeves can be
employed inside the lower part of open-ended driven piles. The sleeves
lead to improved drivability with more soil entering the pile to from soil plug.
The longer is the sleeves, the higher is the plugged length. This is because
there is higher stress release experienced by soils flowing past the
sleeves.
8. What is the significance of reinforced concrete infill in marine
piling system of steel tubular pile with reinforced concrete infill?
(MP3)
Reinforced concrete is designed to fill the void space inside the steel
tubular piles from pile cap to a certain distance below seabed. As
mentioned earlier, steel tubular piles above seabed level is assumed in
design to be completely corroded when approaching the end of design life.
As such, loads from pile caps are transferred directly to reinforced concrete
infill instead of steel tubular piles. The load transfer path below seabed
level is as follows: loads from reinforced concrete infill are transferred to
steel tubular piles through frictional forces between reinforced concrete
infill and steel piles. Therefore, mobilization of frictional forces between
reinforced concrete infill and steel piles is essential to ensure that the piling
system functions properly.
9. Can soil plug be removed in marine piling system of steel tubular
pile with reinforced concrete infill?
During initial driving process, open-ended steel piles are driven through the
soils at their bases. However, shaft friction will gradually develop between
the steel piles and soils inside piles at some time after pile driving. The
hitting action of driving hammers induces forces to the soil and later it
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