- What is piling?
- Auger Piles
What is piling?
Deep foundations are sometimes indicated by geotechnical engineers
when soil conditions are poor or a heavy design load needs to be
Piling makes deep foundations possible. Piles are commonly made
from reinforced concrete and steel
Standard auger piling is the most commonly used pile and is best
suited to partially saturated cohesive and residual soils. The
piles are installed by means of drilling with an auger rig.
Drilling is carried out by rotation of the drilling head and lowering
of the auger allowing it to penetrate into the soil. Once the auger
flight is full with soil it is withdrawn and spun off. This procedure
is repeated until the desired depth is reached.
Once the drilled hole has been completed, a reinforcing cage is lowered
down into position. The shaft is then filled with concrete and is vibrated
to assist compaction of the liquid concrete.
Continuous Flight Auger (CFA)
CFA is suited to saturated ground conditions where collapse and groundwater
are a problem. These piles are installed by means of a hollow continuous
flight auger, and drilled into the ground.
When the desired founding level is reached in soil or rock, cement grout
is pumped into the hollow stem of the auger. The spoil rising up the auger
ensures that soft material cannot fall into the void at the bottom of the
rock socket. This also flushes the base of the pile ensuring a clean contact
with the bedrock.
The auger is then slowly withdrawn from the ground, bringing the soil held
between its flights with it. While grout is simultaneously filling the shaft.
Once the auger has been removed from the grout-filled pile shaft, a steel
reinforcement cage is immediately lowered into the liquid grout.
Various sizes and depths are possible according to design