The document discusses different types of foundations used to transmit the load of a building to the underlying soil. It describes shallow foundations such as wall footings, isolated column footings, and combined footings. Deep foundations including pile foundations, well foundations using caissons and cofferdams, are also summarized. Specific foundation types are defined, like mat/raft foundations used for soft soils, and grillage foundations for supporting high-rise steel structures.

1. FOUNDATION

2. FOUNDATION
 Lowermost part of a building which transmits
the load of building to the underlying earth.

3. Major functions of the foundation
 It distribute non-uniform load of the superstructure
evenly on the subsoil hence it minimize chances of
differential settlement.
 It provides stability against scouring flood water.
 It provides stability against sliding.
 It provides a level surface for the construction of
the superstructure

4. TYPES OF FOUNDATION

5. WALL FOOTING/SPREAD
FOOTING
Footing provided under a
wall.
light load- simple footing is
provided.
Heavy load- stepped
footing is provided.

6. ISOLATED FOOTING/COLUMN FOOTING
It is used to support isolated columns
Size of footing is very large- stepped or sloped
foundation
Reinforced cement concrete footing is provided for
heavy loads.
Load transmitted through the foundation to soil should
be less than bearing capacity of soil.

9. COMBINED FOOTING
 It is constructed for two or more column
 Isolated footings of individual column overlaps or
when external column is situated near the boundary.
 Footing: Rectangular or trapezoidal.

10.  Rectangular footing
 provided when load
acting on two
columns are almost
equal.
 Trapezoidal footing
 Provided when load
acting on the column is
very high
 When one of the
column is very close to
the boundary.

11. Rectangular footing
Trapezoidal footing

12. MAT /RAFT /FLAT FOUNDATION
 It is a concrete slab which cover the entire area
below the building.
 Column loads are heavy.therfor reinforced concrete
slabs are provided
 Mat foundation are used
 When Soil is soft clay or made up land
 Highly compressible soil to reduce settlement.
 It can face large settlement without causing any
harm to the super structure.

13. Raft Foundation

15. Raft Foundation

19. Foundation for Steel columns- Grillage foundation
High rise Buildings are built with steel columns encased
in concrete. Such columns carry heavy load and hence,
they need special foundation to spread the load over a
large area of soil. Grillage foundation is one such
foundation. It consists of one or more tiers of I section
steel beams as shown in figure. The top tier consists of
fewer but large sized steel beams while the lower tier
consists of large number but smaller sized steel beams.
The column load is transmitted to the top tier through a
base plate. The steel beams are not painted but they are
encased in concrete with a minimum cover of 100mm
beyond the edges

20. 1 .PILE FOUNDATION
 The top soil is not capable of taking the load
even at 3m depth.Then we go for pile
foundation.Loads taken to a lower level by means
of long vertical member made up of timber, steel,
concrete.
Deep Foundation

21. PILE FOUNDATION
A pile is a slender column made of
wood,concrete or steel. A plie is either
driven into the soil or formed in situ by
cutting a core in the dround and then
filling with concrete.A group of piles are
provided up to the required depth and are
capped with RCC slab.The structure is built
over the pile cap.Piles transfer the load to
the soil by friction or by direct bearing.In
case of direct bearing,the piles are taken
up to the hard strata

23. Classification of Piles according to method of load
transfer
 Bearing pile
 Friction piles
Bearing piles rest on hard strata and transfer the load by direct bearing.
Such piles are preferred, if hard layer is available at reasonable depth.
Friction Piles transfer the load by friction between the soil and pile. This
type of pile is preferred if hard strata is not available even at considerable
depth. The frictional resistance is assessed before deciding the length of
the pile. The surface of such piles is made rough to increase the skin friction
so as to reduce the required length,

24. Based on material
 Wooden or Timber pile
 Concrete pile
 Steel piles
 Composite piles
 Sand piles

25. Concrete piles
 Precast concrete piles
 Cast-in-situ piles

26. Pre-cast concrete piles
 Are reinforced with steel and
manufactured in factories
 Square section , Circular, and
Octagonal sections with chamfered
corners
 crossectional dimension of piles –
25cm to 60cm
 Length of piles – 3 to 30m
 At lower end, shoes are provided.
 Shoes of 20cm depth and 15cm
width

27. Advantages
 Piles can driven under water also.
High resistance to biological action of the soil.
Disadvantage
They need more time to manfacture
 They are heavy to handle.

28. Cast in situ piles
 Cast at the place where they have to function by
driving a casing into an excavated hole
 Filling up the casing with concrete.
 If the hole is filled with plain concrete only, it is
known as Pressure pile.

29. Cast in situ piles
The load carrying capacity of concrete piles may be
increased by inserting reinforcement caging in the bored
hole and by providing one or two under reams. This is
followed by concreting. Such piles are known as under-
reamed piles. These piles are provided at regular intervals
of 2-3m and then capping beam is provided over them.

30. Pressure pile & Under – reamed pile
Under –reamed pile

31. Timber Piles
• Seasoned wooden piles
• Square or circular piles
• Cross-sectional dimension 20 to 40cm
• length 20 times the cross sectional dimension
• Bottom is sharpened and provided with Iron Shoe
• To avoid decay, the top of wooden piles should be below water
table since wooden piles should not be subjected to alternate
wet and dry conditions .Hence, they are preferred for positions
below water table .The portions above water table are built with
concrete.
• Cheap and can be driven Easily
• Load carrying capacity low
• Likely to be damaged while being driven into the soil.

32. TIMBER PILES

33. Composite Piles
Composite piles may be timber and concrete or steel and
concrete.

35. Steel Piles
Tube

36. I section or H section
Steel Piles

37. Steel Piles
Box - section

38. Cross section of steel piles

39. STEEL PILES :
A steel pile may be rolled steel I-section , or a box
type fabricated section or a tube.
These piles are used as bearing piles .
If tube or box section is used , the soil inside the section is
driven out by compressed air and concrete is filled .
They are commonly used for columns very close to the existing
structures , as they disturb the soil least.

40. Sand Piles :
These piles are formed by boring a hole of the required
diameter and then filling it with sand .
The sand is rammed until it doesn’t escape or settle.
The top of the sand pile is fitted with concrete to prevent the
movement of sand at the top.
Diameter of sand pile is 30 cm and the length is 12 times the
diameter.
It can take loads up to 1000 kN/m2 or 10000 t/m2
They are economical .
They should not be used in earthquake prone regions.

41. Pile caps are provided over a group of piles as shown in figure.
They are usually a concrete platform to provide a platform to
build the structure over them.
The pile cap distributes the load evenly to all piles
The pile should project at least 10cm inside the cap
Pile caps provided to single piles also protects the head of the
pile,
PILE CAPS

42. PILE SHOES
Theory from test
book

43. Pile Driving and Load test on
piles

44. Well foundation

45. Well Foundation
Well foundations are required in areas surrounded by
water, Such foundations are usually required for
foundations of bridge pier,
A cofferdam is a temporary structure built around a
construction site to remove water and make the
construction area reasonably dry.
Caisson is a watertight chamber in which underwater
construction work can be done. After the work is
completed, the caisson becomes a permanent part of
the construction work.

46. Caissons

47. Open Caissons

48. STEINING

49. Box caisson

50. Box Caisson

51. Box Caissons
They are open at top and closed at the bottom.
They are made up of timber, RCC or steel.
They are built on land and then floated to the site and
sunk
Before sinking the box caisson, the bearing surface is
levelled by sand filling
The caisson is sunk by filling with sand or gravel.
The top of the caisson is then plugged.

52. Pneumatic Caissons