This document discusses different types of foundations, including shallow and deep foundations. Shallow foundations include pad, combined, cantilever, strip, and balanced base foundations, which are placed directly below structures and transfer loads to soil. Deep foundations extend below unsuitable soil using piles, which can be displacement piles driven into the ground or bored piles excavated with a lining. Pile caps are concrete structures that connect groups of piles and provide stability and load distribution.

1. 3. FOUNDATION

2. 3.1 FOUNDATION REFERENCE
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SHALLOW FOUNDATION
- Shallow or spread foundations are employed when stable
soil adequate bearing capacity occurs relatively near to
the ground surface.
- Are placed directly below the lowest part of a
subtstructure and transfer building loads directly to the
supporting soil by vertical pressure.
- Types include pad, combined, cantilever, strip, balanced
base foundation and many more.
PAD FOUNDATION
Where soil strengths and loading
conditions permit, the simplest
foundation for a column is pad
foundation.
BALANCED BASE FOUNDATION
- May achieve a column suffi-
ciently close to the restriction
without the additional foundation
depth.
- If compared to cantilever, still
cannot gain the full advantage of
the cantilever foundation)
COMBINED FOUNDATION
As the required area under the
foundation increases it may be
better to take one line of col-
umns and make a continuous
column foundation, known as
combined column base.
CANTILEVER FOUNDATION
- Allows the column to be built
right up to the adjacent building or
boundary with the pads well within
the footprint of building.
- The combined depth of the can-
tilever beam and the bases can
make the founding level deep
Combined foundation section

3. 3.1 FOUNDATION REFERENCE
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STRIP FOUNDATION
- These are suitable for most subsoil and light structural loadings such as those encountered in low to medium rise
domestic buildings where mass concrete can be used.
- Reinforced concrete is usually required in all situation.
Footing options of strip foundation

4. DEEP FOUNDATION
Extend down through unsuitable or unstable soil to transfer
building loads to a more appropriate bearing stratum of
rock or dense sands and gravels well below the
superstructure.
PILE USED: Replacement piles, bored piles
DISPLACEMENT PILE
illustration between replacement and displacement
Simple version of constructon
Perform pile driven into ground
displacing the subsoil through
which it passes
Hole for pile shaft bored in the
ground and the resultant void
filled with reinforced or plain
in-situ concrete
- Often called bored piles since the removal of the
spoil to form the hole for the pile is always carried
out by a boring technique.
- Piles are excavated to required depth where some
piles may need lining as excavation proceeds to
avoid the risk of collapse.
- The lining is then removed as the concrete is
poured. It may only be the top few meters of soil
that are unstable, and in these circumstances the
lining need only be inserted to retain this unstable
layer.
- Used when close to existing buildings where the
allowable amount of noise or vibration is limited.
3.2 FOUNDATION ON SITE
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5. 3.2 FOUNDATION ON SITE
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Detailed bored pile construction

6. 3.2 FOUNDATION ON SITE
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PILE CAP
-Used to connect groups of the columns on top of them.
-These pile groups with the cap provide some stability to the top of the piles that, together with a system of
ground beams connecting the pile caps, will hold the tops in position.
-Provide some margin of safety if one pile has a lower than anticipated loadbearing capacity.
-The distance between the piles is important if each is to achieve its full loadbearing capacity.
-For end-bearing piles the piles should be at least twice the diameter of the pile center to center.
-The connection to the pile cap will be made by taking the reinforcement from the pile into the cap. The top
meter of the pile will be removed to expose the reinforcement and ensure the quality of the concrete at the
top of the pile.
-The cap will be cast with the top of the pile itself around 50mm into the cap to give a mechanical restraint to
the top of the pile.
-It is then common to connect the pile caps together with ground beams that also stabilize the tops of the
piles.
Pile cap arrangements used
Pile cap section