Power Point Presentation on Pile Foundation Subjected to Vertical Load.

1. Analysis of Vertically Loaded Pile Foundation
Presented By
Monojit Mondal
M.Tech in Structural Engineering
National Institute of Technical Teachers Training & Research
Kolkata
Guided By
Dr. T. K. Dey
Assistant Professor
Dept of Civil Engineering

2.  Foundation
 Classification of Foundation
 Shallow Foundation
 Deep Foundation
 Pile Foundation
 Definition of Pile Foundation.
 Advantages and Use.
 Classification
 Load Transfer Mechanism.
 Capacity of Single Pile.
 Capacity of Group Pile.
 Conclusion
 References
Outline of Presentation

3. Foundation
 Most Important part of the
structure.
 Lower most structural element.
 Transmit loads from super
structure to the underlying soil.
Foundation

4. Classification of Foundation
Foundation
Shallow
Foundation
Deep
Foundation
Isolated
Footing
Combined
Footing
Strap
Footing
Mat/Raft
Foundation
Pile
Foundation
Well/Caisson
Foundation

5. Shallow Foundation:
 When foundation placed at relatively shallow depth.
 Load of superstructure is transferred on the soil
Classification of Foundation
Isolated
Footing
Combined Footing Strap Footing

6. Classification of Foundation
Deep Foundation:
 When foundation placed at relatively large depth.
 Load of superstructure is transferred into the soil.

7. Pile Foundation
Pile is a structural
element which is
driven or drilled
into the ground to
transmit the load
coming from the
superstructure into
the soil.

8. 1. Provide a common solution to all difficult foundation problem.
2. Can be used for any type of structure.
3. Can be used in any type of soil.
Advantages of Pile Foundation
1. The load coming from the structure is very high & the
distribution of the load on soil is uneven.
2. Top soil has poor bearing capacity.
3. Water table may rise or fall appreciably.
4. Not possible to maintain foundation trench in dry condition by
pumping.
5. Soil is compressible.
6. Soil is water logged.
7. Soil is of made up type.
Use of Pile Foundation
Pile Foundation

9. Classification of Pile Foundation
A. Based on Materials
1. TIMBER PILE :
 Made from tree trunks
 Well seasoned.
 Straight and free from all defects.
 Usually available length will be 4 to 6m.
 Used where good bearing stratum is
available at a relatively shallow depth.
2. CONCRETE PILE :
 Either precast or cast in-situ.
 Precast piles are generally short lengths.
 Cast-in-situ piles are of variable length with
adequate.
Timber Pile

10. 3. STEEL PILE :
 Usually of rolled sections or thick pipe sections.
 These piles are also used to support open excavations
and to provide seepage barrier.
4. COMPOSITE PILE :
 Two different materials like concrete and steel.
 Mainly used where a part of the pile is permanently
under water.
 The part of the pile which will be under water can be
made of untreated timber and the other part can be of
concrete.
Classification of Pile Foundation
A. Based on Materials

11. Classification of Pile Foundation
B. Based on Method of Installation :
1. DRIVEN PILE :
 The piles are driven into the soil by the impact of a
hammer.
 Also known as Displacement Pile.

12. 2. DRIVEN CAST-IN-SITU PILE :
 A kind of driven pile.
 Steel casing is driven into the ground with a shoe at bottom.
 Filled up the hole by concrete, and the casing is gradually
lifted up as the concrete is poured.
Classification of Pile Foundation
B. Based on Method of Installation :

13. 3. BORED PILE :
 Concrete is poured into prebored holes.
 Also known as Replacement Pile.
 Three type –
a) Small Diameter – up to 600mm
b) Large Diameter – more than 600mm
c) Under reamed – one or more bulbs of larger diameter
than that of the shaft of pile.
Classification of Pile Foundation
B. Based on Method of Installation :

14. Classification of Pile Foundation
1. BEARING PILES:
These piles transfer the
load primarily by bearing
resistance developed at the
toe.
2. FRICTION PILES:
These piles transfer the
load primarily by skin friction
developed along their surface
C. Based on Mode of Function :

15. Classification of Pile Foundation
B. Based on Mode of Function :
3. TENSION PILE:
These piles are also called as
uplift piles. Generally it can be used to
anchor down the structures which are
subjected to uplift pressure due to
hydrostatic force.
4. ANCHOR PILES:
These piles are generally used to
provide anchorage against horizontal pull
from sheet piling.
Anchor Pile

16. 5. COMPACTION PILES:
These piles are used to compact loose granular soil to increase
its bearing capacity. Compaction piles do not carry load and hence
they can be of weaker material. Sand piles can be used as compaction
pile.
Classification of Pile Foundation
B. Based on Mode of Function :
Compaction Pile

17. Classification of Pile Foundation
B. Based on Mode of Function :
6. FENDER PILES and DOLPHIN PILES:
Fender piles and dolphins are used to protect water front
structure from impact of any floating object or ships.

18. Load Transfer Mechanism
The load on pile is gradually increased to a maximum value at the
ground surface before failure known as Ultimate Load capacity of pile. In
which part of the load is carried by the skin friction developed along the
shaft and part by the soil below the tip of the pile.
Load Transfer Mechanism in Pile

19. Load Transfer Mechanism
Now the load QU at the ground surface is gradually
increased,
 maximum frictional resistance along the shaft will be
mobilized when the relative displacement between the
soil and the pile is about 5 – 10mm irrespective of pile
size and length L. However,
 the maximum point resistance will not be mobilized
until the pile tip has moved about 10 to 25% of the pile
diameter (width).
 The lower limit applied to driven pile and upper limit
to bored pile.
At ultimate load
Q(z=0) = Qu. Thus Q1 = QUS and Q2 = QUP

20. Capacity of Single Pile
As per IS 2911(Part1/Sec2,3,)
QUP
QUS
QU
The ultimate bearing capacity of a pile
may be estimated approximately by
 Using a static formulae
 Using a dynamic pile formulae using the
data obtained during driving the pile.
 By conducting an initial load test on a
trial pile tested to its ultimate level.
Pile Capacity by Static Formula :
QU=QUP+QUS
Where,
QU = Ultimate Capacity of Pile
QUP= Ultimate Load Carrying Capacity of Pile Tip
QUS= Ultimate Frictional Resistance

21. 1. PILES IN GRANULAR SOILS :
As per Annex-B, Clause B-1, of IS 2911(Part1/Sec2) : 2010,
capacity of pile is given by –
Pile Capacity by Static Formula
Capacity of Single Pile
As per IS 2911(Part1/Sec2)
QUP
QUS
QU
Where ,
AP = C/S area of pile tip in sq.m
PD = Effective overburden pressure at pile tip in kN/sq.m
(At a depth 15D for φ ≤ 30 and 20D for φ≥ 40)
γ = Effective unit weight of soil at pile tip in kN/cu.m
D = Diameter of pile shaft in m
Ki = Co-efficient lateral earth pressure of ith layer
δi = Angle of wall friction between pile and soil for
ith layer.
Asi= Surface area of pile shaft in the ith layer.
Nq = Bearing capacity factor obtain from Fig 1 of the code
Nγ = Bearing capacity factor obtain from IS 6403
1
1
( ) tan
2
n
u P D q i Di i si
i
Q A P N DN K P A 

   

22. 2. PILES IN COHESIVE SOILS :
As per Annex-B, Clause B-2, of IS 2911(Part1/Sec2) : 2010,
capacity of pile is given by –
Pile Capacity by Static Formula
Capacity of Single Pile
As per IS 2911(Part1/Sec2)
QUP
QUS
QU
Where ,
AP = C/S area of pile tip in sq.m
Nc =Bearing capacity factor (taken as 9)
Cp= Avg cohesion at pile tip in kN/sq.m
αi = Adhesion factor obtain from Fig 2 of the code
Ci= Avg cohesion for ith layer in kN/sq.m
Asi= Surface area of pile shaft in the ith layer.
1
n
u P c P i i si
i
Q A N C C A

  

23. 3. USE OF STATIC CONE PENETRATION DATA :
As per Annex-B, Clause B-3, of IS 2911(Part1/Sec2) : 2010,
capacity of pile is given by –
Pile Capacity by Static Formula
Capacity of Single Pile
As per IS 2911(Part1/Sec2)
qU
QU
Where ,
qU = Ultimate end bearing resistant in kN/sq.m
qc0 = Avg static cone resistance over a depth of 2D
below the pile tip in kN/sq.m
qc1 = Min static cone resistance over a depth of 2D
below the pile tip in kN/sq.m
qc2 = Avg static cone resistance over a depth of 8D
the pile tip in kN/sq.m
8D
2D
0 1
2
2
2
c c
c
u
q q
q
q




24. 4. USE OF STANDARD PENETRATION TEST DATA :
As per Annex-B, Clause B-4, of IS 2911(Part1/Sec2) : 2010,
capacity of pile is given by –
Pile Capacity by Static Formula
Capacity of Single Pile
As per IS 2911(Part1/Sec2)
QU
QU
Where ,
QU = Ultimate end bearing resistant in kN
N = Avg N value at pile tip
L= Length of pile
B = Diameter or minimum width of pile.
AP = C/S area of pile tip
AS = Surface area of pile shaft.
N = Avg N value along the shaft
N
N
Cut off
_
In that case end bearing resistance should not exceed 130NAP
_
13
0.50
s
u P
NAL
Q N A
B
 

25. Pile Capacity by Dynamic Formula
Capacity of Single Pile
As per IS 2911(Part1/Sec3)
As per IS 2911 (Part 1/sec 3) :2010 any established dynamic
formulae can be used to control the pile driving at site giving due
considerations to limitations of various formulae.
where,
W = weight of the driving hammer
h = height of fall of hammer
Wh = energy of hammer blow
Qu = ultimate resistance to penetration
S = pile penetration under one hammer blow
Hiley’s and Engineering News formula are
widely used for determination of pile capacity
Energy of hammer blow = Work done by pile
Basic Principle :
uWh Q s u
Wh
Q
s
or

26. HILEY’S FORMULA : The Hiley formula is expressed as
where,
R = Ratio of weight of pile to the weight of ram
s = set [final penetration of pile per blow (mm)]
C = half of the total elastic compression = ½(C1 + C2 + C3)
C1 = elastic compression of pile cap
C2 = elastic compression of pile
C3 = elastic compression of soil
Cr = coefficient of restitution
ηh = efficiency of hammer
Various coefficients are given below -
Pile Capacity by Dynamic Formula
Capacity of Single Pile
2
1
1
h r
u
Wh C R
Q
s c R
 
 
 

27. HILEY’S FORMULA : The Hiley formula is expressed as
Pile Capacity by Dynamic Formula
Capacity of Single Pile
Pile Material
Range of Driving Stress
× 100 kN/sq.m
Range of C1 (mm) ×25
Precast concrete pile
with packing inside cap
30 – 150 0.12 – 0.50
Timber pile without
cap
30 – 150 0.05 – 0.20
Steel H-pile 30 – 150 0.04 – 0.16
1. Elastic compression C1 of cap and pile head :
2. Elastic compression C2 of pile :
2
1
1
h r
u
Wh C R
Q
s c R
 
 
 
2
uQ L
C
AE


28. HILEY’S FORMULA : The Hiley formula is expressed as
Pile Capacity by Dynamic Formula
Capacity of Single Pile
3. Elastic compression C3 of soil :
The average value of C3 may be taken as 2.5 mm. [the value
ranges from 0.0 for hard soil to 5mm (0.2 inch) for resilient soils)].
4. Pile-hammer efficiency :
Hammer Type ηb
Drop 1.00
Single Acting 0.75 – 0.85
Double Acting 0.85
Diesel 1.00
2
1
1
h r
u
Wh C R
Q
s c R
 
 
 

29. HILEY’S FORMULA : The Hiley’s formula is expressed as
Pile Capacity by Dynamic Formula
Capacity of Single Pile
Material Cr
Wood pile 0.25
Compact wood cushion on
steel pile
0.32
Cast iron hammer in
concrete pile without cap
0.40
Cast iron hammer in steel
pile without cushion
0.55
5. Coefficient of restitution Cr
2
1
1
h r
u
Wh C R
Q
s c R
 
 
 

30. Pile Capacity by Dynamic Formula
Capacity of Single Pile
ENGINEERING NEWS RECORD (ENR) FORMULA :
The formula proposed by A. M. Wellington, editor of the
Engineering News, in 1886, by putting ηh=1, Cr=1 and FOS = 6 in
Hiley’s formula, is
where
Qa = allowable load in kg or kN,
W = weight of hammer in kg or kN,
h = height of fall of hammer in cm,
s = Set i.e. final penetration in cm per blow
(The set is taken as the average penetration per blow for
the last 5 blows of a drop hammer or 20 blows of a
steam hammer).
C = empirical constant = 2.5 cm for a drop hammer,
= 0.25 cm for single and double
acting hammers.
6( )
a
Wh
Q
s c



31. Capacity of Group Pile
S
D
Piles are generally constructed in groups
to support the structural loads.
Dimension of pile block is –
B = (n–1)s + D
Where,
n = No of pile
D = Diameter of pile
B = Width of pile block
S = Spacing between pile
Capacity of pile
block
Sum of individual
pile in group.
Capacity of pile group
Or

32. Pile foundation is widely used for heavily loaded structures.
It is not possible to visual inspection after construction. So
it is mandatory to require good supervision before and
during construction. Still many researches are going on
different aspects of pile foundation
Conclusion

33. References
1. IS 2911 – Part 1 (Section 2 & 3) : 2010, BIS.
2. N.N.Som & S.C.Das, “Theory and Practice of Foundation
Design”, PHI Learning Pvt. Ltd., Aug, 2013.
3. B.M.Das, “Principles of Foundation Engineering”, 4th Edition,
PWS Publishing.
4. http://nptel.ac.in/courses/105108069/7