foundation methods, foundation types, foundation construction process, all type of fundation details, foundation assessment of settlement , raft foundation , mat foundation

1. Chapter- one
Construction of basic components of a building
by k.karthikeyan

2. Foundations:
A foundation is that part of the structure which is
in direct contact with the ground. It transfers the
load of the structure to the soil below so as to
avoid over loading of the soil beneath
It prevents the differential settlement by evenly
loading the sub-strata
It provides a level surface for building operation
It also increases stability of structure by tacking the
structure deep into the ground

3. Foundation

4. Foundations
Foundation are generally built of
Bricks
Stones
Concrete
Steel
Timber etc…
The selection of material and type of
foundation depends upon the type of structure
and the nature of underlying soil.

5. Foundation:

6. Foundation:
Foundation is the lowest part of a structure which
provides a base for the super structure proper.
This term includes the portion of the structure
below the ground level as well as the artificial
arrangement of concrete block, pile, raft grillage,
etc…
Foundation provided to transmit the loads on the
structure including the dead weight of the
structure itself to the soil below

7. Purpose of foundation:
It is often misunderstood that the foundation is
provided to support the load of the structure. In
fact it is a device to transmit the load of the
structure to the soil below
To distribute the weight of the structure over large
area so as to avoid over – loading of the soil beneath
To load the sub-stratum evenly and thus prevent
unequal settlement
To provide a level surface for building operation
To take the structure deep into the ground and thus
increase its stability, preventing overturning

8. Types of foundation
Foundation can be broadly classified into two
types
Shallow foundation
Deep foundation

9. Shallow foundation:
This is the most common type of foundation and
can be laid using open excavation by allowing
natural slopes on all sides.
This type of foundation is practicable for a depth
up to 5m and is normally convenient above the
water table.
The base of the structure is enlarged or spread to
provide individual support. Sines spread foundation
are constructed in open excavation, therefore
they are termed as open foundation

10. Shallow foundation:

11. Shallow foundation:

12. Shallow foundation
This type of foundation is provided for structures of
moderate height built on sufficient firm dry ground.
The various typed of shallow foundation.
Spread footing
Combined footing
Grillage foundation
Mat or raft foundation

13. Spread footing
The base of the member transmitting load to the soil
is wider so as to distribute the load over wider area.
Broadly speaking, all type of foundation mentioned
above can be covered under the term spread.
Type of spread footing
Wall footing
Isolated footing
Inverted arch footing
Continuous footing
Cantilever footing

14. Spread footing

15. Wall footing
It consists of several courses of brick. The lowest course
being usually twice the breadth of the wall above.
The increased base width of the wall is achieved by
providing 5cm (1/2 brick length)offsets on either side of
the wall.
The depth of each course is usually 10cm(thickness of
one brick). In some case, however the bottom courses
are made 20cm(depth of two brick) deep
The footing of various wall thickness have been 90cm,
80cm, 70cm etc..
In case of footing for stone walls, the size of offset is
slightly more than that of the brick wall footing

16. Wall footing
A bed of lean concrete of uniform thickness is first
spread over the entire length of the wall
The depth of the lean concrete bed is normally not
more than 15 cm and its projection on either side of
the wall base varies between 10 to 15 cm

17. Isolated footing
They are used to support individual. They can be either of
stepped type or have projection in the concrete base.
Incase of heavy loaded columns, e steel reinforcement is
provided in both the direction in concrete bed. Generally,
15 cm offset is provided on all sides of concrete bed.
In case of brick masonry columns, an offset of 5cm is
provided on all the four sides in regular layers.
The footing of concrete columns may be a slab, stepped
or sloped type

18. Isolated footing

19. Isolated footing

20. Inverted arch footing
This type of construction is used on soft soils to reduce the
depth of foundation.
Load above an opening are transmitted from supporting
wall through inverted arches to the soil.
In this type of footing the end column must be stable
enough to resist the outward pressure caused by the arch
action
This type of foundation used to be provided for multistoried
building in olden times. However with the advent of
reinforced cement concrete construction practice
One of the drawbacks in this type of construction is that the
end column must be strong enough to resist the outward
pressure caused by the earth action.

21. Inverted arch footing

22. Continues footing
In this type of footing a single continuous R.C. slab is
provided as foundation of two or three or more columns
in a row.
This types of footing is suitable at location liable to
earthquake activities.
This also prevent differential settlement in the structure.
In order to have better stability in the deeper beam is
constructed in between the column

23. Continues footing

24. Cantilever footing or strap
Strap footing consists of two or more individual footings
connected by a beam called a strap. Its also called as
cantilever footing or pump handle foundation
This type of footing may be used where the distance
between the columns is so great that a combined
trapezoidal footing become quite narrow with high
bending moments.
The strap beam does not remain in contact with the soil,
so a strap does not transfer any pressure to the soil
however, because the strap is infinitely stiff, hence it
serves to transfer column loads on to the soil with equal
and uniform soil pressure under both footing

25. Cantilever footing:

26. Cantilever footing

27. Combined footing
 A combined footing supports tow or more columns in row. The
combined footing can be rectangular in shape if both the columns
carry equal loads, or can be trapezoidal if there are space limitation
and they carry unequal loads generally, they are constructed of
reinforced concrete. In the design of footing
When the columns are very near to each other so that their footings
overlap.
 When the bearing capacity of the soil is less, requiring more area
under individual footing.
When the end column is near a property line so that its footing
cannot spread in that direction.
 Combined columns footing are the footing which connects two
columns and if we connect more than two columns it's called
continuous footing.
The combined footing is of three types. They are
•Rectangular combined footing
•Trapezoidal combined footing

28. Combined footing

29. Combined footing

30. Grillage foundation
This type of footing is used to transmit heavy loads from
steel columns to the soils having low bearings power. This
type of arrangement avoids deep excavation and
provides necessary area at the base to reduce the
intensity of pressure.
Grillage footing is made up of rolled steel joists known as
grillage beam provided in single or double tiers.
In double tire arrangement the top tire is laid
perpendicular to the bottom one.
The grillage beams of each tier are held in position by
20mm diameter. Spacer bars or 25mm diameter Pipe
separators

31. Grillage footing
Generally a minimum clearance of 8 cm is kept between the
grillage beam so as to provide facility for placing concrete.
The distance between the flanges of grillage beam should
not be more than one and half to two times the flange width
so that the concrete filling acts monolithically with the beam
A minimum cover of 10 cm is provided on the outer sides of
the external beam as well as above the upper flange of the
top tier
In case of lower beam, the concrete cover under the beam
should ne more than 15 to 20 cm
The concrete filling keeps the joists in position and prevent
them from corrosion

32. Grillage footing

33. Mat or raft foundation:
A raft foundation is a combined footing that covers the entire
area beneath a structure and supports all the columns.
Raft foundation is actually a thick concrete slab resting on a
large area of soil reinforced with steel, supporting columns or
walls and transfer loads from the structure to the soil. Usually,
mat foundation is spread over the entire area of the structure it
is supporting
When the allowable soil pressure is low or the structure loads
are heavy, the use of spread footing would cover more than
half of the building area, and it may prove more economical to
use raft-foundation. They are also used where the soil mass
contains compressible lenses so that the differential settlement
would be difficult to control.

34. Mat or raft foundation
The raft tends to bridge over the erratic deposits and eliminates
the possibility of differential settlement.
Raft tends to bridge over the differential settlement.
Raft foundation is also used to reduce settlement above highly
compressible soils by making the weight of structure and raft
approximately equal to the weight of soil excavated.
A raft may undergo large settlement without causing harmful
differential settlement. For this reason, almost double the
settlement of the permitted for footing is acceptable for raft
Usually when hard soil is not available within 1.5 to 2.5m, a raft
foundation is adopted. The raft is composed of reinforced
concrete beams with a relatively thin slab underneath.

35. Raft or mat foundation

36. Raft or mat foundation

37. Raft and mat foundation

38. Raft or mat foundation

39. Raft foundation:

40. DEEP FOUNDATION
These foundations carry loads from a
structure through weak compressible soil or
fills onto the stronger and less compressible
soils or rocks at depth. These foundations are
in general used as basements, buoyancy
rafts, Caissons:, cylinders, shaft and piles.

41. PILE FOUNDATION
the pile foundation is a construction supported on pile.
A pile is an element of construction composed of
timber, concrete or steel or combination of them
Pile foundation may be define as a column support type
of foundation which may be cast insitu or precast .
The lode of the structure is transmitted by the pile to the
hard stratum bellow or it is resisted by the friction
developed on the side of piles

42. Pile foundation

43. CLASSIFICATION OF PILE
CLASSIFICATION BASED ON THE FUNCTION
CLASSIFICATION BASED ON THE MATERIAL AND
COMPOSITION
CLASSIFICTION BASED ON THE FUNCTION
BEARING PILE
FRICTION PILE
COMPANIED END BEARING AND FRICTION PILE
COMPACTION PILE
UPLIFT PILE
BATTER PILE

44. CLASSIFICATION BASED ON THE MATERIAL AND
COMPOSITION
CEMENT CONCRETE PILE
PRE-CAST CONCRETE PILE
CAST IN SITU CONCRETE PILE
UNDER REAM PILE FOUNDATION
PIER FOUNDATION
STEEL PILE
WELL FOUNDATION OR CAISSONS
TIMBER PILE

45. BEARING PILE
These pile penetrate through the soft soil and their bottoms
or tips rest on a hard stratum.
The soft ground through which the piles pass also gives
some lateral support and this increases the load carrying
capacity of the bearing piles. These piles act as columns.

46. Friction pile
When loose soil extends to a great depth, pile are
driven up to such a depth that friction resistance
developed at the side of the piles equal the load
coming on the piles. The total friction resistance of
piles is obtained by multiplying frictional resistance
of soil with the area of pile in contact with the soil
 By increasing the diameter of the pile
By driving the pile to a grater depth
By making the surface of the pile rough
By placing the pile closely
By grouping the pile

47. COMPANIED END BEARING AND
FRICTION PILE
Transfer the superimposed load both through side
friction as well as end bearing pile

48. Compaction pile
They are used to compact loose granular soils in
order to increase their bearing capacity. These
piles themselves do not carry any load.

49. PILE

50. Timber piles are prepared from trunks of trees. They may
be circular or square they are 30 to 50 cm in diameter with
a length not exceeding 20 times its top width
At the bottom a cast-iron shoe is provided and at the top,
a steel plate is fixed.
Timber pile

51. TIMBER PILE

52. Steel pile
TYPE OF STEEL PILE
•H-PILE
•Box pile
•Tube pile
THE ADVANTAGE OF STEEL PILE
•These piles can easily withstand the stresses due to driving
•These piles can be easily lengthened by welding and can also be cut off easily
•These piles can resist lateral force in a better way
•The bearing capacity of these piles is comparatively high
•These piles can take up impact stresses and can resist lateral force
THE DISADVANTAGE OF STEEL PILE
•The only disadvantage of steel pile is their corrosion

53. Steel pile

54. These piles are manufactured in factory. they may be
tapered or parallel sided.
They may be square octagonal or round in shape
The precast concrete piles are generally used for a
maximum design load of about 80 tones
They may be reinforced to withstand handling stresses
The concrete in the pile should be controlled concrete
and should correspond to M200
PRE-CAST CONCRETE PILES

55. PRE –CAST CONCRETE PILES

56. Pre-cast concrete pile

57. PRE –CAST CONCRETE PILES

58. In this type a bore is dug into the ground by inserting a
casing. This bore is then filled with cement concrete after
placing reinforcement
They may be either cased cast in-situ concrete pile or
uncased cast in-situ concrete pile depending upon
weather the casing is kept in position or is withdrawn
afterwards
CAST IN-SITU CONCRETE PILE

59. CAST IN-SITU CONCRETE PILE

60. CAST IN-SITU CONCRETE PILE

61. UNDER-REAM PILE FOUNDATION

62. PIER FOUNDATION

63. PIER FOUNDATION

64. PIER FOUNDATION

65. Pier foundation

66. Well foundation

67. Well foundation

68. Well foundation

69. FOUNDATION FAILURE