Powerpoint presenta

1. TYPES OF FOUNDATION

2. TYPES OF FOUNDATION
a) Shallow Foundation System
i) Spread Foundation
ii) Mat / Raft Foundation
b) Deep Foundation System
i) Pile iii) Diaphragham wall
ii) Pile walls iv) Caissons

3. SHALLOW FOUNDATION
Advantages
a) Cost (affordable)
b) Construction Procedure (simple)]
c) Material (mostly concrete)
d) Labour (doesn’t need expertise)

4. SPREAD FOOTING FOUNDATION
 Also known as a footer or footing
 It’s an enlargement at the bottom of a column/
bearing wall that spreads the applied
structural loads over a sufficiently large soil
area.
 Each column & each bearing wall has its own
spread footing, so each structure may include
dozens of individual footings.

5. SPREAD FOUNDATION

6.  The foundation consists of concrete slabs
located under each structural column and a
continuous slab under load-bearing walls.
 For the spread foundation system the
structural load is literally spread out over a
broad area under the building
 Most common type of foundation used due
to their low cost & ease of construction.
 Most often used in small to medium size
structure with moderate to good soil condition.

7.  Spread footings may be built in different
shapes & sizes to accommodate individual
needs such as the following:
a) Square Spread Footings / Square Footings
b) Rectangular Spread Footings
c) Circular Spread Footings
d) Continuous Spread Footings
e) Combined Footings
f) Ring Spread Footings

8. a) Square Spread Footings / Pad Foundation
- support a single centrally located column
- use concrete mix 1:2:4 and reinforcement
- the reinforcement in both axes are to
resist/carry tension loads.

9. PAD FOUNDATION

10. b) Rectangular Spread Footings
- Useful when obstructions prevent
construction of a square footing with a
sufficiently large base area and when
large moment loads are present

11. c) Circular Spread Footings
- are round in plan view
- most frequently used as foundation for
light standards, flagpoles and power
transmission lines.

12. d)Continuous Spread Footings / Strip
Foundation
- Used to support bearing walls

13. e) Combined Footings
- support more than one column
- useful when columns are located too close
together for each to have its own footing

14. f) Ring Spread Footings
- continuous footings that have been wrapped into a
circle
- commonly used to support the walls above-ground
circular storage tanks.
- The contents of these tanks are spread evenly
across the total base area and this weight is probably
greater that the tank itself
- Therefore the geotechnical analyses of tanks usually
treat them as circular foundations with diameters
equal to the diameter of the tank.

15. Ring Spread Footings

16. RAFT FOUNDATION
 A foundation system in which essentially the
entire building is placed on a large continuous
footing.
 It is a flat concrete slab, heavily reinforced
with steel, which carries the downward loads
of the individual columns or walls.
Raft foundations are used to spread the load
from a structure over a large area, normally
the entire area of the structure.

17. MAT/RAFT FOUNDATION

18. It is normally consists of a concrete slab
which extends over the entire loaded area.
 It may be stiffened by ribs or beams
incorporated into the foundation.
Raft foundations have the advantage of
reducing differential settlements as the
concrete slab resists differential movements
between loading positions.
They are often needed on soft or loose soils
with low bearing capacity as they can
spread the loads over a larger area.

19. Mat Foundation often considered to be
used when dealing with the following
conditions:
a) The structural loads are so high or the soil
condition so poor that spread footings would
be exceptionally large. As a general rule of
thumb, if spread footings would cover more
than 50% of the building footprint area, a mat
or some type of deep foundation will usually
be more economical.

20. b) The soil is very erratic & prone to
excessive differential settlements. The
structure continuity and flexural strength of
a mat will bridge over these irregularities.
The same is true of mats on highly
expansive soils prone to differential heaves.
c) The structural loads are erratic and thus
increase the likelihood of excessive
differential settlements. Again, the
structural continuity and flexural strength
of the mat will absorb these irregularities.

21. d) The lateral loads are not uniformly
distributed through the structure and thus
may cause differential horizontal
movements in spread footings and pile caps.
The continuity of a mat will resist such
movement.
e)The uplift loads are larger than spread
footings can accommodate. The greater
weight and continuity of a mat may provide
sufficient resistance.

22. f) The bottom of the structure is located below
the groundwater table, so waterproofing is
an important concern. Because mats are
monolithic, they are much easier to
waterproof. The weight of the mat also
helps resist hydrostatic uplift forces from
the groundwater.

23. DEEP FOUNDATION
Extend several dozen feet below the
building
a) Piles
b) Piers
c) Caissons
d) Compensated Foundation

24. PILES?????
 A slender, structural member
consisting steel or concrete or timber.
 It is installed in the ground to transfer
the structural loads to soils at some
significant depth below the base of the
structure.

25. PILES

26. PILES FOUNDATION IS USED WHEN:
 The soil near the surface doesn’t have
sufficient bearing capacity (weak) to support
the structural loads.
 The estimated settlement of the soil exceeds
tolerable limits
 Differential settlement due to soil variability
or non-uniform structural loads is excessive
 Excavations to construct a shallow foundation
on a firm soil are difficult or expensive.

27. LOAD CAN BE TRANSFERRED BY PILE
TO THE GROUND BY 2 WAY THAT IS:
a) End Bearing Piles OR
- Pile will transmit load into the firm soil layer
of the ground such as rock, gravel, very
dense sand
b) Friction Piles
- Pile transmit the load from the structure to
the penetrable soil by means of skin friction
or cohession between the soil & the
embedded surface of the pile.

28. There 2 type of End Bearing Piles That is Preformed
Timber Pile & In-Site-Reinforced Concrete Pile

29. Friction Pile May Be Used To Support DownWard Load

30. TYPES OF PILES
a) Concrete Piles
i) Cast-In-Place Concrete Piles
ii) Precast Concrete Piles
iii) Drilled Shafts
b) Steel Piles
I) H-Piles ii) Cylindrical iii) Tapered
c) Timber Piles
d) Composite Piles

31. CAST IN PLACE CONCRETE PILES
i. Formed by driving a cylindrical steel shell
into the ground to the desired depth and
cavity of shell is filled with fluid concrete.
ii. The steel shell doesn’t contribute to the load
transfer capacity of the pile.
iii. It’s purpose is to open a hole in a ground and
keep it open to facilitate the construction of
concrete pile. (same function as formwork)
iv. Vigilant quality control & good construction
practice are necessary to ensure the integrity
of cast-in-place piles.

32. Among the advantages of Cast-In-Place
Concrete are as follows:
 Can sustain hard driving
 Resistant to marine organism
 Easily inspected
 Length can be changed easily
 Easy to handle and ship

33. PRECAST CONCRETE PILES
i. Usually have square/circular/octagonal
cross sections.
ii. Fabricated in a construction yard from
reinforced or pre-stressed concrete.
iii. Disadvantages of this pile are problems in
transporting long piles, cutting and
lengthening.
iv. It has higher capacity than timber piles.

34. STEEL PILES
i. It comes in various shapes & sizes
ii. Steel H-Piles are rolled steel sections
iii. Steel pipe piles are seamless pipes that can
be welded to yield lengths up to 70m.
iv. They are usually driven with open ends into
the soil.
v. A conical tip is used where the piles have to
penetrate boulders & rocks.
vi. However it needs to be treated before
embedded in corrosive environment.

35. TIMBER PILES
i. Have been used since ancient times
ii. Length of timber piles depends on types
of trees used to harvest the piles,
iii. Common length are 12m
iv. It is susceptible to termites, marine
organisms and rot within zones exposed
to seasonal changes.
v. Eventhough it’s cheaper but it has low
capacity and can’t take hard driving.

36. TYPES OF PILE CHOSEN DEPENDS
ON FOLLOWING FACTORS:
a) What type of pile is readily available
b) Location & type of structure (magnitude
of loading)
c) Ground Condition (soil type)
d) Cost
e) Durability

37. TYPES OF PILE CONSTRUCTION
a) Displacement Piles
- It cause the soil to be displaced radially as
well as vertically as pile shaft is driven or
jacked into the ground.
b) Non Displacement Piles
- It cause the soil to be removed and the
resulting hole filled with concrete or a pre
cast concrete pile is dropped into the hole
and grouted in.

38. Displacement Pile

39. Replacement Pile / Non Displacement Pile

40. TYPES OF DISPLACEMENT PILES:
 Can be classified into different types base
on how they are constructed and how they
are inserted.
 There are 3 types as follows:
a) Totally Preformed Displacement Piles
(precast concrete or steel pile)
a) Driven & Cast-In-Place Displacement Pile
b) Helical Cast-In-Place Displacement Piles

41. a) Totally Preformed Displacement Piles
- Precast Concrete or Steel Pile
b) Driven & Cast-In-Place Displacement Pile
- This type of pile can be of 2 forms.
- The first involves driving a temporary steel
tube with a closed end into the ground to
form a void in the soil which is then filled
with concrete as the tube is withdrawn.
- The second type is the same except the steel
tube is left in place to form a permanent
casing.

42. c) Helical Cast-In-Place Displacement Piles
- This type of construction is performed using
a special type of auger.
- The soil is however compacted, not removed
as the auger is screwed into the ground.
- The auger is carried on a hollow stem which
can be filled with concrete, so when the
required depth has been reached concrete can
be pumped down the stem & the auger
slowly unscrewed leaving the pile cast in
place.

43. METHOD OF INSTALLATION
a) Dropping Weight or Drop Hammers
- commonly used method of insertion of
displacement piles
b) Diesel Hammers
- Most suitable to drive pile in non cohesive
granular soil
c) Vibratory Hammers or vibratory method of
pile driving
- very effective in driving piles through non
cohesive granular soil
c) Jacking Method Of Insertion

44. Diesel Hammer
Rapid controlled explosions can be produced by the
diesel hammer.
The explosions raise a ram which is used to drive the
pile into the ground.
Although the ram is smaller than the weight used in
the drop hammer the increased frequency of the
blows can make up for this inefficiency.
 This type of hammer is most suitable for driving
piles through non-cohesive granular soils where the
majority of the resistance is from end bearing.

45. Vibratory Method of Pile Driving
Vibratory methods can prove to be very
effective in driving piles through non cohesive
granular soils.
The vibration of the pile excites the soil grains
adjacent to the pile making the soil almost free
flowing thus significantly reducing friction
along the pile shaft.
However the large energy resulting from the
vibrations can damage equipment, noise and
vibration propagation can also result in the
settlement of nearby buildings.

46. Pile Driving Rig - raise and temporarily support the pile
that being driven and to support the pile hammer.

47. Pile Driving Rig

48. Dropping Weight / Drop Hammers
 A weight approximately half that of the
pile is raised a suitable distance in a guide
and released to strike the pile head.
 When driving a hollow pile tube the
weight usually acts on a plug at the bottom
of the pile thus reducing any excess
stresses along the length of the tube during
insertion.

49. Pile Installation Using Drop Hammer

50. Jacking Method Of Insertion
 Jacked Piles are most commonly used in
underpinning structures
 By excavating underneath a structure short
lengths of pile can be inserted and jacked
into the ground using the underside of the
existing structure as a reaction.

51. Jacking Method Of Insertion

52. NON DISPLACEMENT PILES
THERE ARE 4 TYPES THAT IS:
a) Small Diameter Cast-In-Place
b) Large Diameter Cast-In-Place
c) Partially Preformed Piles
d) Grout or Concrete Intruded Piles

53. PIERS
 It’s a vertical bridge support.
 It’s a foundation for carrying a heavy
structural load which is constructed in site
in a deep excavation.

54. Among the things to be taken in consideration
during construction of pier are as follows:
a) Drilling through wet or caving soils may
need use of temporary steel casing. May also
require the use of a tremie & a pump to
dewater the hole & place concrete. This is
more expensive and require a large diameter
hole.
b) For the purpose of reinforcing, it’s difficult
to get bars to the full depth of the pier with
the proper concrete cover in deep holes.Use
centralizes. Use large diameter bars versus
more bars.

55. c) Don’t leave holes open for any length of time
even in dry condition. Cuttings fall in or etc.
Have concrete on site and fill right after
drilling and cleaning.

56. Pier

57. Pier

58. Pier

59. Pumping Water Out Of The Hole For The Excavation
Of The Pier

60. Constructing The Pier Framing

61. Completed Pier Framing
Post Footing & Detail

62. Ramp Is Installed
Ramp Is Bolted

63. Floor Decking
Installation
Completed Pier

64. CAISSON FOUNDATION

65. WHAT IS CAISSONS?
 It’s a prefabricated hollow box or cylinder.
 It is sunk into the ground to some desired
depth and then filled with concrete thus
forming a foundation.
 Most often used in the construction of bridge
piers & other structures that require foundation
beneath rivers & other bodies of water.
This is because caissons can be floated to the
job site and sunk into place.

66. Basically it is similar in form to pile
foundation but installed using different way
used when soil of adequate bearing strength
is found below surface layers of weak
materials such as fill or peat.
It’s a form of deep foundation which are
constructed above ground level, then sunk
to
the required level by excavating or dredging
material from within the caisson.

67.  A caisson foundation consists of concrete
columns constructed in cylindrical shafts
excavated under the proposed structural
column locations
 Caissons are drilled to bedrock or deep into
the underlying strata if a geotech eng. find the
soil suitable to carry the building load.

68.  It’s created by auguring a deep hole in the
ground.
 Then, 2 or more ‘stick’ reinforcing bar are I
inserted into and run the full length of the
hole and the concrete is poured into the
caisson hole.
 The caisson foundations carry the building
loads at their lower ends, which are often
bell-shaped.

69. Caissons

70. TYPES OF CAISSONS
 Box Caissons
 Excavated Caissons
 Floating Caissons
 Open Caissons
 Pneumatic Caissons
 Sheeted Caissons

71. Reinforced Concrete Caissons

72. Caissons

73. Caisson As One Of The Elements In This Structure

74. TO BE CONTINUED, NEXT TOPIC