Deep foundation and floating foundation (shallow). Building construction.

1. Building construction

3. Purpose
• Distribute the load
• Make the bearing surface uniform
• Prevent movement
• Increase stability
Ground Level
Super-structure
foundation
Distribute building load to the ground

4. Size and depth of a foundation is
determined by:
Structure and size of
building it supports
 Nature and bearing
capacity of the ground
supporting it

5. The two basic
types of
foundations:
Shallow Deep

6. Deep Foundation

8. Definition
It extends down through unsuitable or unstable
soil to transfer building loads to a more
appropriate bearing stratum of rock or dense
sands and gravels.
Unlike shallow
foundations, deep
foundations
distribute the load of
into the ground
vertically rather than
laterally.

9. Cases
• Weak soils near the surface
• Loads very high
• Soil stratum is not strong or stable
Example: Petronas Twin Towers in Malaysia

10. The Two Principal
Types of Deep
Foundations:
Pile Caisson
Pile

11. Pile Foundation

12. Definition
A system of end bearing or friction piles, pile
caps and tie beams for transferring building
loads down to a suitable bearing

13. Types
Piles may be of treated
timber poles but for large
buildings, steel H
sections, concrete filled
pipes, or precast
reinforced or prestressed
concrete are more
common.
Timber H-Sections Pipe Piles Precast Concrete

14. Cases
• Stratum of required bearing capacity is at
greater depth
• Steep slopes
• Compressible soil
• Water-logged soil
• Soil of made-up type
Slope

15. Advantages
• Can be used for any
type of structure and
in any type of soil.
• Can be precast
• Can be used in places
where it is advisable
not to drill holes
Disadvantages
• Must be reinforced
to withstand stresses
• Requires heavy
equipment for
handling and driving.
• Foundations of
adjacent structures
are likely to be
affected due to the
vibrations

16. Process and Machinery
Piles are driven into the earth by a pile driver,
composed of a tall framework supporting
machinery for lifting the pile in position before
driving, a driving hammer, and vertical rails or
leads for guiding the hammer

17. Pile driver
For driving piles into the ground

18. Driving Hammer

19. Drilling rig
Creates holes in the earth sub-surface

20. Classification of
Pile Foundation
Based on Function
End-Bearing Piles Friction Piles

21. End-Bearing Pile
Depends principally on
the bearing resistance
of soil or rock beneath
their feet for support.

22. Friction Bearing Pile
Depend principally on the
frictional resistance of a
surrounding earth mass for
support.

23. Caisson Foundation

24. Definition
Formed by boring with a large auger or
excavating by hand a shaft in the earth to a
suitable bearing stratum and filling the shaft
with concrete
Auger

25. Crane
Crane for filling caisson

26. Cases
• Suitable for underwater
foundation where the
foundation should be
extended up to or below the
river bed to obtain stability
• Often used when
constructing bridge piers and
other such foundations

27. Advantages
• Extended to large
depths
• Cost is relatively less
• There is direct and
easy passage to reach
the bottom of
caisson so any
obstruction can
easily be removed.
Disadvantages
• Precautions should
be taken, otherwise
it may lead to fatal
accidents.
• Labor cost is high.
• If obstacles like
boulders or logs are
encountered, then
progress becomes
slow.

28. A temporary casing may be required to seal out
water, sand or loose fill from the shaft during
excavation

29. The base of a
caisson may be
enlarged into a
bell shape to
increase its
bearing area and
resist uplift from
soil expansion.
The bell may be
excavated by hand
or be formed by a
bucket
attachment to an
earth auger that
has a set of
retractable blades
Some caissons
are drilled into a
stratum of solid
rock in order to
gain additional
frictional support

30. Floating Foundation (Shallow)

31. Definition
• Does not use footings
• Support on soft soil
• Consists of a stiff reinforced concrete slab
• Distributes the load by columns to the soil
Why is it called
“floating”?
Because it
"floats" on the
soil.

32. Cases
• Often seen in warmer climates
Why?
 Ground freezing and thawing is less of a
concern
No need for heat ducting underneath the floor
• Common in garage floors and mobile home
slabs

33. Process
Install reinforced steel
rods or heavy wire mesh
(to prevent floor from
cracking and breaking)
Pour concrete

34. Advantages
• Termites are not a
problem
• Inexpensive
• Moisture barrier
• For areas with lower
load bearing
capacities
Disadvantages
• Expansion not
possible
• Lack of underground
access
• Exposes the building
to flood damage in
even moderate rains