Introduction, uses, selection of pile, types of piles, pile cap and pile shoe, pile driving methods, micro piling, causes of failures of piles, Heaving of piles

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PREPARED BY : ASST. PROF. VATSAL D. PATEL
MAHATMA GANDHI INSTITUTE OF
TECHNICAL EDUCATION &
RESEARCH CENTRE, NAVSARI.

2. A pile is a slender structural member mad of steel, concrete, wood
or composite material.
A pile is either driven into the soil or formed in-site by excavating a hole
and filling it with concrete.
In case, the strata of good bearing capacity is not available near the ground,
the foundation of the structure has to be taken deep with the purpose of
attaining a bearing stratum which is suitable in all aspects.
The most common forms of deep foundations are:
1. Pile foundation
2. Cassions or well foundations
3. cofferdams

3. The load of the superstructure is heavy and its distribution is uneven.
The top soil has poor bearing capacity.
The subsoil water is high so that pumping of water from the open trenches
for the shallow foundation is difficult and uneconomical.
There is large fluctuation in subsoil water level.
Where timbering to the trenches is difficult and costly.
The structure is situated on the sea shore or river bed, where there is danger
in scouring action of water.
Canal or deep drainage lines exist near the foundation,
The top soil is of expensive nature.
Piles are used for the limit foundation of transmission towers, off-shore
platforms which are subjected to uplift forces.

4. 1. Nature of structure
2. Loading condition
3. Availability of funds
4. Availability of materials and equipments
5. Type of soil and its properties
6. Ground water table
7. Self weight of pile
8. Durability of pile
9. Cost of pile
10. Maintenance cost
11. Length of pile required

5. 12. Number of pile required
13. Case study of adjacent building
14. Facilities available for pile driving
15. Difficulties in pile driving
16. Adaptability to varying length
17. Presence of acids and other material in the soil that would injure the pile
18. Erosion of soil near the structure

6. 12. Number of pile required
13. Case study of adjacent building
14. Facilities available for pile driving
15. Difficulties in pile driving
16. Adaptability to varying length
17. Presence of acids and other material in the soil that would injure the pile
18. Erosion of soil near the structure

7. For the structures on the land, the driven and cast-in place piles are usually
the cheapest for moderate loadings and unhampered site conditions.
For the foundations of wharf- structures and jetties on sea shore, the driven
piles or driven and cast-in –place cased piles are preferred.
In case of piling is to be done very near to some existing structure,
open ended tube piles or H-piles may work out to good choice.
Piles used to support marine structures or structure above open water should
precast type.
The jacked piles are suitable for under-pinning existing structures.
For heavy structure, large diameter bored piles are the most economical
type.

8. If the subsoil consists of silt on alluvium for appreciable depth, the pile will
act as friction pile.
In case the ground is very weak or loose and it is intended to use cast-in-situ
pile, casting will be required to prevent the inflow of soil into the pile hole.
In adverse condition, where the ground water flow is strong, pile with
permanent casing should be used. Alternatively, precast piles may be used.
In case the soil strata is comparatively firm uncased cast-in-situ piles
or precast pile may be selected.
For reducing the length of pile in the firm strata, pedestal pile will be more
effective.
In situation where it is necessary that the pile should penetrate into rock for
some depth, H-piles may work out to be good selection.
In case the soil is firm clay, drilled piles with or without enlarged base, may
work out to be a economical choice.

9. In situation where there is possibility of the soil being chemically
aggressive, high quality precast concrete piles should be selected.
Timber piles may work out to be economical if they are used for the
foundation of timber trestles structures with moderate loads or If the piles
are to be used for protecting concrete docks, etc.
Timber piles are not suitable from marine conditions as they are likely to
be affected by borers or insects.

10. While selecting a particular type of pile, the cost of pile, cost of driving,
cost of maintenance of pile and availability of fund should given due
consideration.

11. 1. End bearing pile
2. Friction pile
3. Compaction pile
4. Tension pile
5. Anchor pile
6. Fender pile
7. Better pile
8. Sheet pile

12. These piles penetrate through the soft soil and their bottoms or tips rest on a
hard stratum.
These piles act as columns.
The soft material surrounding the pile provides some lateral support.

13. When loose soil extends to a great depth, piles are driven up to such a depth
that frictional resistance developed at the sides of the piles equal the load
coming on the piles.
Friction piles are used when a hard stratum is available at greater depth. The
total frictional resistance can be increased in following ways:
By increasing the length of pile
By increasing the diameter of pile
By making the surface of the pile rough
By placing the piles closely
By grouping the piles.

14. When piles are driven in loose granular soil with aim of increasing the
bearing capacity of soil, the piles are termed as compaction plies.
These piles themselves do not carry any load.

15. These piles anchor down the structure subjected to uplift due to hydrostatic
pressure or due to overturning moment.
It is also called uplift pile.
Turning
force
Friction
force

16. Anchor piles provide anchorage against horizontal pull from sheet piling or
other pulling force.
Fender piles are used to protect water front structures against impact from
ships or other floating objects.
Better piles are used to resist large horizontal forces or inclined forces.
Sheet piles are used as bulk heads or as impervious cutoff to reduce seepage
and uplift under hydraulic structures.

17. Timber piles
Steel piles
Concrete piles
Composite piles

18. Timber piles are made of-tree trunks driven with small end as a point. 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 the top a steel plate is fixed.
They have small bearing capacity and are not permanent unless treated.

19. Economical where timber is easily available.
Can be driven rapidly & as such saves time.
Because of elasticity, timber piles are recommended for sites subjected to
unusual lateral forces e.g. ship, ferry terminals.
Do not need heavy machinery and elaborate technical supervision.
Being light, they can be easily handled.
They can be easily withdrawn if needed.

20. This pile cannot take heavy loads and are unsuitable for use as end
bearing pile.
Liable to decay or deteriorate by salt water/insects.
Restricted length. It is rather difficult to procure piles in required size
and length.
It is difficult or rather impossible to drive these piles into hard stratum.

21. Steel piles are usually of rolled H-sections or thick pipe sections.
These piles are used to withstand large impact stresses and where less
distribution from driving is desired.
Steel sheet piles and H-piles are generally used to support the open
excavation and to provide seepage barrier.

22. Concrete piles are either precast or cast in situ.
Precast piles are cast and cured at the casting site and then transported to
the site for installation.
These piles are adequately reinforced to with stand handling stresses
along with working stresses.
Precast piles are normally suitable for short lengths.
Cast-in-situ piles are constructed by drilling hole in the ground and then
filling the hole by concrete after placing the reinforcement.

23. Pre-cast piles are those which are manufactured in factory or at a place
away from construction site, and then driven into the ground at the place
required.
These piles require heavy pile driving machinery.
Precast piles may be square, octagonal or circular in cross section, and
may be tapered or parallel sided longitudinally.

24. The size of pile may vary from 30cm to 50cm in cross sectional
dimension, and up to 20m or more in length.
The reinforcement may consists of longitudinal steel bars of 20mm to
40mm in diameter, 4 to 8 nos. with ties of 6 to 10 mm diameter at
100mm c/c spacing for top and bottom 1m length and 300mm c/c
spacing for middle length.
A concrete cover of at least 50mm is provided.
The grade of concrete should be M20.

25. 1. The formwork for the pile is prepared and it is coated with soap
solution or oil to prevent adhesion.
2. The cage of reinforcement is prepared as per design and this cage is
then placed in the formwork. A concrete cover of at least 50mm is
provided.
3. A concrete grade M20 is prepared with proportion 1:1.5:3. The size
of coarse aggregate varies from 10mm to 25mm.
4. The concrete is laid in the formwork and well compacted using
vibrators.
5. The forms are removed after 3days and the piles are kept in the same
position for about 7 days or so.
6. The piles are then shifted to a curing tank and after a period of about
three or four weeks, they become ready for use.

26. They will be cast well before the commencement of the work resulting in
rapid execution of work.
The position of reinforcement in pile is not disturbed from its original
position.
They can driven under water.
The piles can be loaded soon after they have been driven to desire depth.
Any numbers of piles can be manufactured at a convenient place and this
may prove to be economical.
These piles are highly resistant to biological and chemical actions of the
subsoil.

27. These piles are heavy. Therefore they require special equipment for
handling and transportation.
If sufficient care is not taken, these piles may break during transport or
driving.
They require heavy pile driving equipment.
Extra reinforcement is require to bear handling and driving stresses.
Hence these piles are costly.
The length of the pile is restricted since it is depends upon the transport
facilities.
It is difficult to increase the length of the pile previously estimated on the
basis of bore holes.
If the pile is found to be too long during driving, it is difficult and
uneconomical to cut the pile.

28. The Raymond standard pile is used primarily as a friction pile.
It is provided with uniform taper of 1 in 30 resulting in shorter piles.
The length of pile vary from 6 to 12m. The diameter of piles vary from
40 to 60 cm at the top and 20 to 30 at the bottom.
the shell is driven into the ground with a collapsible steel mandrel or
core in it having the same paper.
The shell is gradually filled with concrete up to the top.

29. Mac Arthur is a pile of uniform diameter using the corrugated steel shell
which remains in place as in Raymond piles.
A heavy steel casing with a core is driven into the ground.
When the desired depth is reached the core is withdrawn and a
corrugated steel shell is placed in the casing.
Concrete is placed in the shell by gradually compacting it and
withdrawing the steel casing.

30. This pile consists of helically welded shell of steel plate. A concrete plug
is provided at the bottom of the shell.
Driving Is done by allowing pile hammer to fall on the concrete plug.
The casing is driving to the desired depth and then it is filled with
concrete

31. Swage piles are used with advantage in some soils where the driving is
very hard or where it is desired to leave water tight shell, for some time
before filling the concrete.
In the first stage a steel shell is placed on a precast concrete plug and a
steel core which is not long enough to reach the plug is inserted in the
plug.
In the second stage the pipe is driven over the plug until the core reaches
the plug the pipe is swaged out by the taper of the plug thus forming a
water tight joint.
In the third stage the pipe is driven to a specified depth.
In the fourth stage after the pipe was reached the desired depth the core
is removed and the pipe is filled with concrete.

32. These piles are used in locations where increase in the end bearing area
is desired. The pile uses a concrete plug of shape of button.
There piles have been used up to lengths of about 23 m and for loads up
to 50 tonnes.
In the 1st stage a steel pipe with 12mm thick walls is set on the concrete
button. The concrete button has a diameter about 25mm larger than the
pipe.
In the 2nd stage the pipe and button are driven to a specified depth.
In the 3rd stage a corrugated steel shell is inserted in the pipe resting on
the button.
In the 4th stage the casing is withdrawn leaving the button in place and
the shell is filled with concrete. Reinforcement may be used if
necessary.

33. Advantages:
These piles are cheap as no casing will be left in the ground.
Special handling equipment is not required.
Concrete is not liable to damage from driving.
Cutting of excess lengths is not required .
Storage space not required.
Disadvantages:
Great skill is required.
It is likely to be damaged from subsoil pressure and ground movements
which result from pile driving and obstruction in ground.

34. Simplex piles can be driven through soft or hard soils.
In this type of piles a steel tube fitted with a cast iron shoe is driven into the
ground up to the desired depth.
Reinforcement if necessary is put inside the tube concrete is then poured
into the tube and the tube is slowly withdrawn concrete being tamped
leaving behind the cast iron shoe.

35. In this type of pile a plug of dry concrete gravel is formed on the ground by
heavy removable pipe shell.
A diesel operated drop hammer of 20 to 30 KN weight is driven on the
concrete plug.
When the tube has reduced the desired depth the tube is held in position by
cables and the hammer is applied to the concrete plug forcing it down and
outward.
In the next stage the shaft is formed by introducing successive charges of
concrete ramming each in turn and withdrawn the casing gradually about
300mm at a time.
The pile diameter in franki piles vary from 50cm to 60cm while the
enlarged base may have a diameter of about 90cm.
The pile has a load carrying capacity of 60 to 90 tonnes.

36. These pile are used where the ground is soft thus offering little frictional
resistance to the flow of concrete. Both standard and expanded piles are
formed by the vibro-process.
These piles are formed by driven a steel tube and shoe filling with concrete
and withdrawing the steel tube.
Standard vibro piles are made in size of 35,45,50cm diameter for loads of
60 to 70 tonnes.
A steel tube fitted with a cast iron shoe is driven in the ground by 2 to 2.5
tonnes hammer operated by steam or compressed air delivering up to 40
blow per minute with a stroke of about 1.4m.

37. This type of pile are used where thin bearing stratum is reached with
reasonable depth.
The core and casing are driven together into the ground till they reach the
desired level.
The core is taken out and a charge of concrete is placed in the tube. The
core is again placed in the casing to rest on the of poured concrete.
Pressure is applied on the concrete through the core and as the same time
the casing is withdrawn.
The process is repeated till the casing is completely removed.

38. These are formed wit the help of a casing tube boring auger and compressed
air equipment. These piles are especially suitable for those congested sites
where heavy vibrations and noise are not permissible.
A hole is bored into the ground by means of an auger and as the boring
proceeds the hole is lined by a steel tube.
When the tube reaches the required depth the boring tool is withdrawn.
In the 2nd stage a layer of concrete is laid and pressure cap is provided at
the top of the tube.
The process is repeated till the pile is completed.

39. These piles are developed by C.B.R.I., Roorkee (U.P) for serving as
foundations for black cotton soils, filled up ground and other types of soils
having poor bearing capacity.
An under-reamed pile is a bored cast-in-situ concrete pile having one or
more bulbs or under-reams in its lower portion.
The bulbs or under-reams are formed by under reaming tool.
The diameter of under remed pile varies from 20 cm to 50 cm and that of
bulb varies from 2 to 3 times the diameter of pile.
The length of under reamed piles is about 3 m to 8 m.
The spacing of piles mat vary from 2m to 4m.
The under reamed piles can also be used for sandy soils with high water
table.

40. The load carrying capacity of under reamed piles can be increased by
adopting piles of larger diameter or by extending the length of piles or by
making more bulbs at the base.
A single under reamed pile has only one bulb at the bottom.
When two or more bulbs are provided at the base, it is known as multi-bulb
under reamed pile.
The vertical spacing between two bulbs varies from 1.25 to 1.50 times the
diameter of bulb.

41.  The center to center distance of successive piles is known as pile spacing.
 It has to be carefully designed by considering the following factors,
 Types of piles and Material of piles
 Length of piles
 Grouping of piles
 Load coming on piles
 Obstruction during pile driving
 Nature of soil through which piles are passing.
 The spacing between piles in a group can be assumed based on
the following:
 1- Friction piles need higher spacing than bearing piles.
 2- Minimum spacing (S) between piles is 2.5.
 3- Maximum spacing (S) between piles is 8.0.
S

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S
2
Piles
3
Piles
S
4
Piles
5
Piles
S 6
S
Piles S S
7
Piles

43.  Most pile foundations contain group of
piles instead of single pile.
 The piles forming the group of piles may be
arranged in square, rectangular, triangular or
circular as per the requirement.
 The bearing capacity of pile group may not be
necessarily equal the sum of the bearing capacity
of individual piles forming a group.

44.  The efficiency of a pile group is define as the ratio of the load carrying capacity of
the pile group to the sum of the load carrying capacities of the individual piles.
 Factors of Group Efficiency:
 The number, length, diameter, and spacing of the piles
 The load transfer mode (friction vs. bearing)
 The sequence of installation
 The soil type
 The interaction, if any, between the pile cap and the soil
 The direction of the applied load

45.  The process of forcing the piles into the ground without excavation is termed as
the pile driving.
 The piles should be driven vertically.
 However, a tolerance of eccentricity of 2% of the pile length is permissible.
 The eccentricity is measured by means of plumb bob.
 The hammer is guided between two parallel steel members known as leads.

46. Boom
Crane
Pile
Lead
Hammer
Helmet
Pile Gate
Stabbing
Points

47.  Drop hammer.
 Single acting hammer.
 Double acting hammer.
 Diesel hammer.
 Vibratory hammer.

48. 53
Driving
shoe
hammer
Drop Hammer
Hammer Guide
Pile (pre cast/cast in situ)
Soil

49.  Low operation
 Low equipment cost
 Simple

50.  A hammer (or ram or monkey) is raised
by winch and allowed to fall or drop by
gravity on the top of the pile.
 The drop hammer is provided with lugs
so that it can slide in the leads.
 A lifting eye or hook is provided to tie it
with the rope.
 The weight of drop hammer varies from
0.5 to 2 tones (5 to 20 kN).
 The height of fall may vary from 1.5 to 3
meters.
 The number of blows that can be
imparted varies from 4 to 8 per minute.

51.  If the hammer is raised by steam, compressed air or internal combustion, but is
allowed to fall by gravity along, it is called a single acting hammer.
 The energy of such hammer is equal to the weight of the ram times the height of
fall.
 The weight of single acting hammer is about 2 tonnes (20kN).
 The fall is about 1 meter.
 the number of blows of the hammer may vary from 50 to
60 per minute.

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Piston
Ram
Helmet
Pile

53.  The double acting hammer employs steam or air for lifting the ram and for
accelerating the downward stroke.
 The weight of the hammer is only 500 kg (5 kN) but because of accelerating effect
of steam (or air) pressure, it has an effect of a weight of 3 tonnes (30.kN).
 It operates with succession of rapid blows,the number varying from 100 to 200
blows perminute.
 For light hammers, the number of blows may be even as high as 300 per minute.
 The pile driving is very quick.
 These hammers are very useful for driving piles under water.

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55.  The total driving energy is the sum of
the impact of the ram plus the energy
delivered by explosion.
 The diesel hammer is a small, light
weight self-contained and self-acting
type, using gasoline for fuel.

57.  If the driving has to be carried out by hammer, then following factors should be take
into consideration.
 The size and weight of the pile.
 The driving resistance which has to be overcome to achieve the desired
penetration.
 The available space and head room in the site because the hammer has to be
dropped from certain height.
 The availability of cranes.
 The noise restrictions which may be in force in the locality.

58.  The ultimate load carrying capacity, or ultimate bearing capacity (Qf) of a pile is
defined as the maximum load which can be carried by a pile and at which the pile
continues to sink without further increase of load.
 The allowable load Qa is the safe load which the pile can
carry safely and is determined on the basis of
 Ultimate bearing, resistance divided by appropriate factor of safety.
 The permissible settlement,
 Overall stability of the pile foundation.
 The load carrying capacity of a pile can be determined by the following methods.
 Dynamic formulae
 Static formulae

59.  Used for precast concrete piles.
 When a pile hammer hits the pile, the total driving energy is equal to the weight
of hammer times the height of drop or stroke.
 In addition to this, in the case of double acting hammers, some energy is also
imparted by the steam pressure during the return stroke.
 The total downward energy is consumed by the work done in penetrating the pile
and by certain losses.
 The various dynamic formulae are essentially based on this assumption.

60. Engineering New Formula:
Qa = allowable load
W = weight of hammer (KG)
H = height of fall (CM)
F = factor of safety = 6
S = final set (penetration) per blow,
(Usually taken as average penetration, cm per blow for
the last 5 Blows of hammer or last 20 blows for steam
hammer.)
C = empirical constant.
= 2.5 cm for drop hammers, and
= 0.25
hammers.
For single acting steam
hammer
For drop hammer
cm for single or double acting
For double acting
hammer
a= effective area of piston (cm2)
P=mean effective steam pressure (kg/cm

61. Hiley's Formula (IS formula):
 Indian standard IS: 2911(Part I): 1964 gives the following formula based on
original expression by Hiley :
Qf = ultimate load on pile.
W = weight of hammer in kg
H = height on drop of hammer, in cm
S = penetration or set, in cm, per blow
C = total elastic compression= C1 + C2 + C3
C1,C2, C3 = temporary elastic compression of dolly and packing, pile and soil
respectively.
h = efficiency of hammer, variable from 65 percent for same double acing steam
hammers to 100 percent for drop hammers released by trigger.
b = efficiency of hammer blows (i.e. ratio of the energy after impact to striking energy of
ram).

62.  The static formulae are based on the assumption that the ultimate bearing capacity
Qf of a pile is the sum of the total ultimate skin friction Rf and total ultimate point
or end bearing resistance Rp.
As = surface area of pile upon which the skin friction acts
Ap = area of cross-section of the pile on which bearing resistance acts. For
tapered piles, Ap may be taken as the cross-sectional area at the lower one-third
of the embedded length.
rf = average unit skin friction, which may be taken equal to unit cohesion for
cohesive soils.
rp = unit point or toe resistance, which may be taken as 9c for cohesive soils.

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