This document discusses pile foundations and provides classifications and details regarding pile types, requirements, construction, testing, and load determination. It defines a pile foundation as a deep foundation system that uses slender columns (piles) made of materials like concrete or steel to transfer structural loads into soil. Piles can be classified based on construction method (driven, bored), material (wood, steel, concrete), and load transfer mechanism (end bearing, friction, combined). Key factors requiring pile foundations and details regarding pile spacing, installation, concreting, and testing methods are also summarized.

1. PILE FOUNDATION

2. TYPES OF FOUNDATION
1) Shallow Foundation
Eg : Single footing, Strap footing, Raft foundation etc.
2) Deep Foundation
Eg: Pile foundation, Well foundation, Pier foundation etc.

3. WHAT IS PILE FOUNDATION…?
• A Pile foundation is a kind of deep foundation, can be defined as a slender column
or long cylinder made of materials such as concrete or steel which are used to
support the structure and transfer the load at desired depth either by end bearing
or skin friction

4. REQUIREMENT OF PILE FOUNDATION
1. The upper strata is very weak and compressible
2. Irregular structure having chances of differential settlement
3. Resist horizontal forces in addition to vertical load. Earth pressure for earth
retaining structure and high wind and seismic forces for tall structures.
4. Foundation soil is susceptible to Erosion and Scour
5. Suitable for transmission tower, Off-shore platform which are subjected to uplift
6. Expansive soil (Black cotton soil) which swells and shrinks as water content
changes, Piles are used to transmit the load below active zone.

5. CLASSIFICATION OF PILES
• BROAD CALSSIFICATION
• DRIVEN (DISPLACEMENT PILES)
• BORED (NON DISPLACEMENT PILE)
• ON THE BASIS OF MATERIAL
• TIMBER
• STEEL
• PCC
• RCC
• PSC
• COMPOSITE

6. CLASSIFICATION OF PILES
Method of construction
Driven precast piles- Driven in Soil by applying blows of heavy
Hammer on the top
Driven cast in situ piles- Driving a casing with closed bottom end, later
filled with concrete. Casing may or may not be withdrawn.
Bored precast piles- A bore is excavated inside soil and a pile
casted in yard put into it.
Bored cast in situ piles – Excavating a bore into ground and filling it
with concrete.

7. CLASSIFICATION OF PILES
Mode of load transmission
1. End bearing piles
Transmit the load through their bottom tip to a hard strata
2. Friction piles
Transmit the load through skin friction between pile surface and surrounding soil
3. Combined End Bearing and Friction pile
Transfer the Load by both skin friction and end bearing.

8. CLASSIFICATION OF PILES...CONTD
• SECTIONAL AREA
• CIRCULAR
• SQUARE
• TUBULAR
• OCTAGONAL
• H-SECTION
• SIZE
• MICRO (MINI) PILES (<150 mm)
• SMALL DIAMETER PILE (>150 mm < 600 mm)
• LARGE DIAMETER PILE (>600 mm)

9. SELECTION OF TYPE OF PILE:
DRIVEN OR CAST-IN-SITU ?
• Availability of Space : Driven Piles require large areas and head room since it
needs larger and heavier driving rigs
• Proximity to Structures : driving cause vibrations in ground which may cause
damage to nearby structures
• Reliability : Precast driven piles ensure good quality of material, uniform section
of piles
 Cast in situ piles can be formed to any desired length and no cutting of pile or
addition to length required

10. SPACINGOF PILES
Minimum Centre-to-centre distance between piles
Shall be governed by
1. Practical aspects for installing the piles,
2. Diameter of pile, and
3. Nature of load transfer to the soil and possible reduction in the
capacity of group of piles thereby

11. SPACING…contd
FOR END BEARING PILES
• Pile founded on Hard strata and deriving the capacity mainly from end bearing,
Minimum spacing 2.5D
• 2.0 D for piles resting on rock
FOR FRICTION PILES
• Sufficiently apart to avoid overlapping zones of soil
• Not less than 3 D
MAX SPACING 4 D

12. INSTALLATION OF PILE…

13. TREMIE CONCRETING
• Minimum cement content not less than 400 kg/cum and slump between 150-180 mm
• The tremie should be water tight and a hopper attached to its head by a water tight
connection.
• Tremie pipe should have minimum dia of 200 mm for pile dia more than 600 mm.
• A steel plate or ball shall be placed at bottom of hopper and the hopper is filled with
concrete. The first charge of concrete sent by removal of this plate and ball.
• The tremie should always be kept full of concrete and should always remain inside
concrete.

14. TREMIE CONCRETING…CONTD
• Concreting of pile should be uninterrupted
• In case of interruption, shall be resumed within 1-2 hr. Tremie shall not be taken
out and raised and lowered time-to-time to prevent concrete to set.
• In case of withdrawal of tremie for any reason, the tremie may be inserted 60 cm
to 100 cm in old concrete and resume the concreting.
• Top of concrete should be min 600 mm above cut off level to remove all laitance
and weak concrete.

15. TREMIE CONCRETING

16. OVERLOADING
When a pile in a group, designed for a certain safe load is found, during
or after execution, to fall just short of the load required to be carried by
it, an overload up to 10 percent of the pile capacity may be allowed on
each pile.
The total overloading on the group should not, however, be more than
10 percent of the capacity of the group subject to the increase of the
load on any pile being not more than 25 percent of the allowable load
on a single pile.

19. PILE LOAD TEST
Initial Load Test – Test conducted on pile at the initial stage of project to find the
design load of pile. It is done on non working piles.
Routine Load Test – Test conducted on working pile to check its capability to
take working load without exceeding permissible settlement.

20. PILE LOAD TESTING
Purpose of Initial Load Test
 Arrive at safe load by applying FOS on ultimate load capacity
determined from tests
 To provide guidelines for setting up limits for acceptance of
routine tests
 To have a check on safe load calculated by static or dynamic
formulae

21. PILE LOAD TESTING
• Initial Test
 For small size projects ( total piles less than 1000) , a minimum of two tests
 For large projects ( piles more than 1000), a minimum of two tests for first 1000 piles
and additional one test for every additional 1000 piles and part thereof
 Initial test piles should be installed by the same technique, same type of equipment as
that proposed for working piles
 The test load in INITIAL TEST shall not be less than 2.5 times the estimated safe load
 Initial pile load test shall preferably be carried out before taking up the piling job

22. PILE LOAD TESTING
• Routine Test
• On 0.5 percent of total number piles subject to a minimum one test, can be
increased to 2% depending on nature of strata.
• Purpose
• It is carried out on a working pile with a view to check whether pile can take
the working load assigned to it
• Detection of any unusual performance contrary to the findings of initial test.
• Workmanship

23. ACCEPTANCE CRITERIA FOR ROUTINE TEST
1. The routine test shall be carried out for a test load of at least 1.5 times the working
load
2. The maximum settlement at the load being not greater than 12 mm for piles up to
600 mm dia
18 mm or 2 percent of pile dia whichlever less for piles of dia more than 600mm

24. PILE LOAD TESTING METHODS
• Maintained Load Method : applicable for both initial and routine test
• Cyclic Method : this method is used in case of initial test to find out separately
skin friction and point bearing load on single piles

25. MAINTAINED LOAD METHOD
• Pile Head should be chipped off till sound concrete met. The projecting reinforcement
cut off or bent suitably and pile head finished smooth.
• Test should be carried out by applying a series of vertical downward incremental load,
each increment being about 20 percent of safe estimated load on pile
• Each stage of loading shall be maintained till the rate of movement of the pile top is
not more than 0.2mm/h or until 2h have elapsed, whichever is earlier subject to a
minimum of 1 h
• The test load is maintained for 24 hours

26. MAINTAINED LOAD METHOD
• Vertical loading on single pile shall be continued till one of the following takes
place :
In case of Initial Load Test:
1. Applied load reaches 2.5 times the safe estimated load; or
2. Max settlement of pile exceeds a value of 10 percent of pile diameter in case of
uniform dia piles and 7.5 percent bulb dia of under-reamed piles.

27. MAINTAINED LOAD METHOD
(b) In case of routine load test :
1. Applied load reaches 1.5 times the working load ; or
2. Max settlement of pile exceeds a value of 12 mm for piles dia up to and
including 600mm and 18 mm or maximum of 2 percent of pile dia whichever is
less for piles of dia more than 600 mm.

28. SAFE LOAD INITIAL TEST
• The safe load on a single pile will be least of the following
• (A) For piles upto 600 mm dia :
• Two third of the final load at which total displacement attains a
value of 12 mm
• 50 % of the final load at which the total displacemnt equals 10 %
of the dia. of pile for uniform dia piles and 7.5 percent of bulb dia
for under-reamed piles.

29. SAFE LOAD-INITIAL TEST
FOR PILES MORE THAN 600 MM DIA :
 Two-thirds of the final load at which the total displacement attains a value
of 18mm or maximum of 2 percent pile diameter whichever is less.
 50 % of the final load at which the total displacemnt equals 10 % of the
dia. Of pile for uniform dia piles and 7.5 percent of bulb dia for under-
reamed piles.

30. LOAD SETTLEMENT CURVE
SAFE LOAD ( piles upto 600
mm dia)
Least of 2/3 P1 or ½ P2

31. THANK YOU