2. Contents:
-Introduction
-Uses of pile
-Selection of type of pile
-Types of pile
-Pile spacing
-Group of piles
-Efficiency of group of pile
-Pile hammer
-Micro piling
-Causes of failure of piles
2
3. A pile is a slender structural member made of steel, concrete, wood or
composite material.
When the depth of foundation is more then the width of foundation
,then it is termed as deep foundation.
The deep foundations are classified as below:
Pile foundation Cofferdams Caissons
Pile foundations are used extensively for the support of buildings,
bridges, and other structures to safely transfer structural loads to the
ground and to avoid excess settlement or lateral movement. They are
very effective in transferring structural loads through weak or
compressible soil layers into the more competent soils and rocks
below.
3
4. 4
1: The load of super structure is heavy and its distribution
is uneven.
2: The top soil has poor bearing capacity.
3: Subsoil water level is high so that pumping of water
from the open trenches for the shallow foundation is
difficult and uneconomical.
4: large fluctuation in subsoil water level.
5: structure is situated near river bed, where there is
danger of scouring action of water.
6: the top soil is of expansive nature.
SITUATIONS WHERE A PILE FOUNDATION IS NEEDED
7. FACTORS AFFECTING THE
SELECTION OF TYPE OF PILES
• Nature of structure
• Loading conditions
• Availability of funds
• Availability of materials and equipments
• Types of soil and its properties
• Ground water table
• Self weight of pile
• Durability of pile
• Cost of pile
• Maintenance cost
• Length of pile required
• Number of piles required
• Facilities available for pile driving
• Presence of acids and other materials in the soil that would injure the pile
7
8. Classification of Piles
Based on the function
1. End bearing Pile
2. Friction Pile
3. Compaction Pile
4. Tension Pile
5. Anchor Pile
6. Fender Pile
7. Batter Pile
8. Sheet Pile
Based on the material & composition
1. Concrete Pile
2. Timber Pile
3. Steel Pile
4. Composite Pile: Concrete & Timber, Concrete & Steel
Based on the method of installation
1. Driven Pile
2. Cast-in-situ Pile
3.Driven and cast- in- situ Pile
8
9. End bearing piles
• If the piles are driven into the ground until a
hard stratum is reached and the piles act as
a pillars supporting the super structure and
transmitting the load to the hard ground.
11. Friction pile
• When loose soil extended to a great depth, pile are
driven up to a such a depth that frictional resistance
developed at the sides of the piles equals the load
coming on the piles.
12.
13. 13
• Compaction piles are used to compact loose granular
soil, thus increasing their bearing capacity. The
compaction piles themselves don’t carry load. The pile
tube, driven to compact the soil, is gradually taken out
and sand is filled in its place thus forming a ‘sand pile’.
COMPACTION PILE
14. 14
• Tension piles or uplift piles- Anchor down the
structure subjected to uplift due to hydrostatic
pressure or due to overturning moment.
TENSION PILE
15. 15
• Fender piles- Used to Protect water front structures against
the impact from ships or other floating objects.
• Sheet piles- Used as impervious cutoff to reduce seepage
and uplift under hydraulic structures.
• Batter piles- Used to resist large horizontal or inclined
forces.
• Anchor piles- Provide anchorage against horizontal pull
from sheet piles or other pulling forces.
20. 1. PRE CAST CONCRETE PILE
• PRE-CAST CONCRETE PILES
• The precast concrete piles are generally used for maximum design load of
about 80 tonnes. They must be reinforced to withstand handling stresses.
• They require space for casting and storage, more time to set and curing
before installation and heavy machine are required for handling purpose
and driving.
• These piles require heavy pile driving machinery which is mechanically
operated.
• The size of pile may vary from 30cm to 50cm in cross-sectional dimension,
and up to 20m length or more in length.
• Reinforcement may include longitudinal steel bars of 20mm to 40mm in
diameter, 4 to 8 nos. with lateral tie 5 to 10mm wire spaced at 10cm c/c for
top and bottom 1m length and 30cm c/c for the middle length.
• A cast steel shoe, properly secured to pile by mild steel straps, is provided
at its lower end. Toe protect the pile and help in penetrating into hard
strata during driving. 20
24. 24
PROCEDURE FOR FORMING PRECAST CONCRETE PILES
• The form work of required space is prepared. Usually metal forms are used
for mass manufacture. The inner sides of the form is coated with either
soap solution so that soil does not adhere to the side.
• The reinforcement cage, as per design, is placed in the form, maintaining
proper cover all around. Cast steel shoe is also placed, and is secured to the
reinforcement with the help of mild steel straps.
• Concrete is then placed in the form and well vibrated with the help of form
vibrators. Mix of concrete 1:2:4 with maximum size of aggregate equal to
19mm.
• When the pile is driven into soil it is subjected to impact stress at its head.
• Remove the form after three days. But the piles are kept in same place for
7days. The piles are then shifted to curing tank where concrete is allowed
to mature for at least 4weeks before being driven.
• Maturing period can be reduced if, raped hardening cement is used instead
of normal Portland cement.
25. 25
ADVANTAGE OF PRECAST CONCRETE PILES:
• The piles are manufactured in the factory. Hence proper control can be
exercised over the composition and design of these piles.
• The position of reinforcement in the pile cannot be disturbed.
• Large numbers of piles are manufactured at a time in the factory or any
other place, cost of manufacturing will be less.
• These piles can be driven under water. If the soil water contain more
sulphate. Thus pre-cast concrete piles have added advantage in such
circumstance.
• These piles provide highly resistant to biological and chemical action of
the subsoil.
DISADVANTAGE OF PRECAST CONCRETE PILES:
• These piles are very heavy.
• They require equipment for handling and transporting purpose.
• The length of the pile is restricted since it depends upon the transport
facilities.
• It is very difficult to increase the length of the pile, previously estimated
on the basis of bore
• holes.
28. Cast-in-situ concrete piles
• In this type of concrete piles, a bore is dug into the
ground by inserting. This bore is then filled with
cement concrete after placing reinforcement, if any.
29. RAYMOND PILE
• (RAYMOND STANDARD CONCRETE PILE) is used primarily as a friction
pipe. It is uniform heavy taper of 1in30 result in short piles for equal
driving resistance or higher driving resistance for equal lengths, than piles
of lesser or no taper.
• Length of piles varies from 6 to 12m. diameter of piles vary from 40 to
60cm at top and 20 to 30 at bottom.
• The shell is driven into the ground with a collapsible steel core in it having
the same taper.
• When the pile is driven to desired depth the core is mechanically
collapsed and withdrawn, leaving the shell inside the ground.
• Shell is inspected internally by using the flash or drop light.
• Shell is gradually filled with concrete up to the top.
29
32. 32
• This pile is of uniform diameter, best example on non-taper
pile.
• It used extra steel casing heavy gauge in driving pile.
• Steel casing with central core is driven into ground.
• After reaching the desired depth, core is withdrawn and
shell is placed in casing.
• After that concrete is placed in the shell, by gradually
compacting it, and withdrawing steel casing.
• These piles are used in place where the driving soil is very
hard and it is designed to kept water tight before filling the
concrete in shell.
MAC-ARTHUR PILES
33. MAC-ARTHUR PILES
shaped into a series of parallel
ridges and grooves so as to give
added rigidity and strength.
33
35. 35
BSP-BASE DRIVEN PILES
• This pile consist of a
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.
36. 36
SWAGE PILES
• 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.
38. 38
BUTTON BOTTOM PILES
• 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.
40. Uncased cast in situ concrete piles
• These piles are comparatively cheap, as no casing will
be left in the ground. But, great skill is required in this
case to achieve the desired results.
• The common types of uncased cast in situ concrete
piles are:
1. Simplex piles
2. Franki piles
3. Vibro piles
4. Pedestal piles
5. Pressure piles
40
41. 41
• 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.
SIMPLEX PILES
43. 43
FRANKI PILES
• 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.
46. 46
VIBRO PILES
• 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.
47. 47
PRESSURE PILES
• 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
48. 48
PEDESTAL PILES
• 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.
49. 49
Cast-in-Place Concrete Piles
Among the advantages of cast-in-place concrete piles are the
following:
1. The lightweight shells may be handled and driven easily.
2. Variations in length do not present a serious problem. The
length of a shell may be increased or decreased easily.
3. The shells may be slipped in short lengths and assembled at
the job.
4. Excess reinforcing, to resist stresses caused by handling only,
is eliminated.
5. The danger of breaking a pile while driving is eliminated.
45
6. Additional piles may be provided quickly if they are needed.
50. 50
Cast-in-Place Concrete Piles
Among the disadvantages of cast-in-place concrete piles
are the following:
1. A slight movement of the earth around an un-
reinforced pile may break it.
2. An uplifting force, acting on the shaft of an uncased and
unreinforced pile, may cause it to fail in tension.
3. The bottom of pile may not be symmetrical.
51. 51
•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.
TIMBER PILE
52. TIMBER PILES
Advantages:
• The more popular lengths and sizes are available on
short notice.
• They are economical in cost.
• They are handled easily, with little danger of breakage.
• They can be cut off to any desired length after they are
driven.
• They can be pulled easily in the event removal is
necessary.
52
53. 53
Disadvantages:
1. It may be difficult to obtain piles sufficiently long and
straight for some projects.
2. It may be difficult or impossible to drive them into
hard formations.
3. It is difficult to splice them to increase their lengths.
4. While they are satisfactory when used as friction
piles, they are not suitable for use as end-bearing piles
under heavy loads.
5. The length of life may be short unless the piles are
treated with a preservative.
55. 55
Steel piles are useful where driving conditions are
difficult and other types of piles are not suitable. Usually
used for building and bridge foundations.
The piles are in form of I, H sections and steel pipe piles.
They can be used for:
1. Foundation piles
2. Sheet piles
3. Superstructure columns
STEEL PILE
56. 56
• Steel I and H Piles
Steel H piles are similar to I-beam except that
the cross-section is generally heavier and the
flange width and beam height is nearly the same.
57. Steel Piles
Advantages:
High axial working capacity. Wide variety of sizes. Easy on-
site modifications. Fairly easy to drive, minimal soil
displacement, good penetration through hard materials (with
shoe).
Disadvantages:
High cost, difficulty in delivery, relatively higher corrosion,
noisy driving.
57
59. • Piles of two different materials are driven one
over the other, so as to enable them to act
together to perform the function of a single pile.
• This type of composite pile is used with the
object of achieving economy in the cost of piling
work.
Composite Piles
61. 61
Sand piles:
These piles are formed by making holes in the ground
and then filling them with sand. If sand is kept
confined, it possesses great crushing strength and becomes
incompressible.
A bore hole of required diameter, then filled with sand and it is
well rammed. The top of sand pile is filled with concrete to
prevent the sand ejecting upwards due to lateral pressure.
62. 62
Classification based on method of
installation
Driven piles:
These piles are driven into the ground by applying blows with a heavy
hammer on their tops.
Timber, steel and precast concrete piles are installed by driving, which
may be driven into position either vertically or at an inclination.
Driven and cast-in-situ piles:
These piles are formed by driving a casing with a closed bottom end into
the soil.
The casing is later filled with concrete.
The casing may or may not be withdrawn, it is called uncased pile, and if
not withdrawn, it is called cased pile.
63. 63
Bored and cast-in-situ piles:
These piles are formed by excavating a hole into the ground
and then filling it with concrete.
Screw piles:
These piles are screwed into soil.
Jacked piles:
These piles jacked into the ground by applying a downward
force with the help of a hydraulic jack.
65. NON - LOAD BEARING
PILES
This piles are used to function as the separating members
below
ground level and they are generally not designed to take any
vertical load.
This piles are also known as the sheet piles.
The materials used for the construction of non load bearing
piles are,
i. Timber sheet piles
ii. Steel sheet piles
iii. Concrete sheet piles
65
66. SHEET PILES
Sheet piles are thin piles, made of plates
of concrete, timber or steel, driven into the
ground for either separating members or
for stopping seepage of water. They are
not meant for carrying any vertical load.
Therefore, sheet piles are also termed as
non-load bearing piles.
66
67. 67
SHEET PILES
• Sheet piles are never used to provide vertical support
but mostly used to act as retaining walls. They
are used for the following purposes:
o To construct retaining walls in docks, and other
marine works.
o To protect erosion of river banks.
o To retain the sides of foundation trenches.
o To confine the soil to increase its bearing capacity.
o To protect the foundation of structures from erosion
by river or sea.
o To isolate foundations from adjacent soils.
70. SHEET PILES
1.Concrete
sheet piles:
Concrete sheet piles are
reinforced, precast units. The
width of each unit may vary
from 50 cm to 60 cm and
thickness varies from 2 cm
to 6 cm.
The reinforcement is in
the form of vertical bars and
hoops. 70
71. 2. Steel sheet pile:
Steel sheet piles are most commonly used.
They are trough shaped and when the piles are
interlocked with alternate once reversed.
They are generally made from steel sheets 20 to
30 cm wide and 4 to 5 m long.
71
72. Different types of steel sheet piles are:
1. Arch web steel sheet pile.
2. Built up steel sheet pile.
3. Z-type steel sheet pile.
4. Corrugated steel sheet pile.
5. Deep arch web steel sheet pile.
6. Universal joint steel sheet pile.
72
76. These piles are successfully 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 is a 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 reamed pile
varies from 20cm to 50cm and that of bulb varies from 2
to 3 times the diameter of pile.
Under reamed piles
76
77.
78. METHOD OF CONSTRUCTION
-The equipment for the construction of pile consists of
auger boring guide, spiral auger with extension road,
under-reamer with bucket and concreting funnel etc.
-The auger should be rotated slowly with a constant
downward pressure and taken out when it is full with soil.
-The holes for casting pile in the ground may be bored by
using hand augers.
-For deeper borings , the length of the auger can be
increased by adding suitable extension rods or pipes.
-In sites where the sub soil water table is high, bentonite
slurry are used to retain the sides of the bore hole against
collapse.
-After the pile holes are ready for concreting , the
reinforcement cages are lowered in the holes and
concrete is poured by the use of funnel.
82. PILE SPACING
• The spacing of pile is the center to center distance between two
successive piles.
• The factors to be considered while deciding the pile spacing are as
follows:
1. The nature of soil through which the pile is driven.
2. The obstruction during pile driving
3. The type of pile
4. The depth of penetration
5. The area of cross section of the pile
6. The centre to centre distance of piles in a group
7. The manner in which the pile supports the load
8. The material of pile
82
83. GROUP OF PILES
• Sometimes the piles are arranged in
close- spaced groups. When the
piles are driven to the required
depth, their tops are cutoff a same
level and then the pile cap is
provided.
• In case of single pile small
pressure is developed in the
surrounding soil. And in case of
group piles, the pressure
developed surrounding the
individual piles will overlap
laterally and the pressure in the
overlapping zone will be sufficient 83
84.
85. EFFICIENCY OF GROUP OF PILE
The efficiency of a pile group is taken as the ratio of the
load carrying capacity of the pile group to the sum of the
load carrying capacities of the individual piles.
It is determined by two methods:
•converse Labbore equation.
•Field rule.
86. 86
Converse –labarre Equation:
Where,
n1= number of piles in row
n2= number of rows
D= diameter of pile
d= spacing of pile
Feld’s rule:-
According to this rule the value of each pile is reduced by one-sixteenth
on account of the effect of nearest pile in each diagonal or straight row
of which the particular pile is a member.
88. PILE ACCESSORIES
In case of Wooden Piles, Steel Piles, Pre-cast Concrete Piles, to
protect the top and bottom of the Pile while driving into the
ground and to facilitate easy Pile driving certain accessories are
required as under:
1. Pile Cap
2. Pile Shoe
88
89. PILE CAP REINFORCEMENT
• In case of driven pile, piles are driven in to the ground by
applying blows of a heavy hammer on their tops. Thus to
protect the top of the pile cap is provided.
• Pile caps carrying very heavy point loads tend to produce
high tensile stresses at the pile cap.
• Reinforcement is thus designed to provide:
– Resistance to tensile bending forces in the bottom of the cap
– Resistance to vertical shear
89
90. PILE SHOE
• While driving wooden or steel pile by hammer the
bottom end of the pile gets damaged causing
difficulty in driving.
• Therefore, a pile shoe is fitted at the bottom end of the
pile to protect the pile and to facilitate easy pile
driving.
• Pile shoe are made of cast iron, steel iron.
90
91. Various Types of Pile Shoe
1. Square Pile Shoe
2. Wedge shape Shoe
3. Round Pile Shoe
4. Steel Trap shoe
5. Socket Type pile shoe
6.Closed end shoe for pipe pile.
91
93. PILE DRIVING
The operation of inserting a pile into the ground is known as pile
driving.
Piles are commonly driven by means of a hammer supported by a
crane or a special device known as a Pile Driver.
The various methods of pile driving are:
1. Hammer driving
2. Vibratory pile driver
3. Water jetting & hammering
4. Partial Angering method
93
94. 94
1. Hammer driving:- For hammer driving following equipment's are
used.
1. Pile frame
2. Pile hammer
3. Leads
4. Winches
5. Miscellaneous equipment's
Hammers adopted for driving the pile are of the following
types:
1. Drop hammer
2. Single acting hammer
3. Double acting hammer
4. Diesel hammer
5. Vibratory hammer.
95. 95
1. Pile frame:-
• Pile driver with crawler mounted crane rig commonly
used for pile driving. The hammer between guided
between two parallel steel channels known as leads.
• Pile Driving Rigs provide basic operation of lifting the
pile, holding the pile in position, hammering it into the
ground or of pulling it out of the ground and guiding
the pile in the desired direction of movements.
• It supports the boom, the winch, mechanism, driving
hammer, the guiding leaders and a platform for
mounting the auxiliary equipment such as jet pumps,
drilling auger etc.,
97. PILE HAMMER:
1.Drop hammer:
The drop hammer in the pile driving equipment consists of
a heavy ram in between the leads. The ram is lifted up to a
certain height and released to drop on the pile. This type is
slow and therefore not in common use.
100. 2. Single acting
hammer
• In a single acting
hammer a heavy ram is
lifted up by steam or
compressed air but
dropped by its own
weight.
• The energy of a
single acting hammer
is equal to the weight of
the ram times the 100
101. 3. Double acting hammer:
The double acting hammer
employs steam or air for
lifting the ram and for
accelerating the downward
stroke.
The energy of a double
acting hammer is equal to
weight of ram or effective
pressure of 1 times the
height of fall.
101
103. 4. Diesel hammer:
• The diesel hammer is a small, light weight and highly
mobile. They use gasoline for fuel. To start the
operation, the ram is raised, and the fuel is injected. As
the ram released, the ram falls and compressed air and
fuel.
105. 105
Leads:-
• The leaders guide the pile and the hammer
during operation which extents to the entire
height of the rigs.
• In case pile driven below the rigs in to
excavations or trenches extensible leaders are
used.
• It enable hammer to deliver blow axially to pile.
106. 106
Winches:
• It is used to lift hammer & pile.
• It should be light with single drum or double drum. It
may be fitted with reverse gear system.
107. WATER JETTING AND HAMMERING
• The use of a water or
air jet to facilitate pile
driving by displacing
parts of the soil.
• Jetting is useful in
driving piles through
very dense granular
material.
107
108. 108
VIBRATORY HAMMER:
• Very effective in driving piles
through non cohesive granular
soils.
• Pile is driven by making
vibration.
• The vibration can be
produced by electrically /
hydraulically.
• Penetration rates can
approach up to 20 m/min in
moderately dense granular
soils.
• It can be used with another
109. 109
PARTIAL AUGERING METHOD:
• Inclined piles(batter pile) are usually
advanced by partial augering.
• In this technique, a power auger is used to
drill the hole for a part of the depth.
• The pile is then inserted in the hole & driven
with hammer to the required depth.
110. CAUSES OF FAILURE OF PILES
• Absence of statistical data regarding the nature of soil
strata through which the piles are to be driven.
• Actual load coming on the pile being more than the
design load.
• Bad workman ship in case of the cast-in-situ cement
concrete piles.
• Breakage due to over driving especially in case of the
timber piles.
• Buckling of piles due to removal of side support,
inadequate lateral support, etc. 110
111. CAUSES OF FAILURE OF PILE
• Lateral forces (wind, waves, currents etc.) not being taken
into the design of the pile.
• Improper choice of the type of pile.
• Improper choice of the method of driving the pile.
• Improper classification of pile.
• Insufficient reinforcement or misplacement of
reinforcement in case of the R.C.C. piles.
• Wrongful use of pile formula for determining its load
bearing capacity.
111
112. Proposed by A.M. Wellington in the following general
form;
Qa=
F;S+CͿ
WH
Where, Qa= allowable load
W= wt. of the hammer H= height of the fall
F= F.O.S, taken as ͞6͟
S= final set (penetration) C= empirical
constant
2.5 for drop hammer,&
0.25 for single and double acting
hammers.
ENGINEERING NEWS FORMULA:
113. IS: 2911 gives the following formula based on the original
expression of Hiley:
𝜼 𝒉WH 𝜼 𝒃Qd=
𝑺+𝑪/𝟐
Where, Qd= ultimate load on a pile
C= toatal elastic compression
C = C1+C2+C3, temporary elastic compression of
dolly
and packing, pile & soil respectively.
𝜼 𝒉 = efficiency of hammer
𝜼 𝒃=efficiency of hammer blow (i.e. ratio
of energy after impact to striking energy
of ram)
HILEY’S FORMULA:
114. Ultimate bearing capacity of a pile is determined by the formula
given below;
Qd= Rf + Rp= Asrf + Aprp
Where, Rf = total ultimate skin friction
Rp= total ultimate point or end bearing
resistance
As= surface area of pile upon which the
skin friction acts
Ap= area of cross section of pile on which
bearing resistance acts
rf = average skin friction
rp= unit point or toe resistance
A FOS 2.5 or 3 may be adopted for
finding the allowable load.
STATIC FORMULA
115. PILE LOAD TEST
Preliminary pile design
is first carried out on
the basis of site
investigations,
laboratory soil testing,
and office study.
Pile load tests are
then carried out to
refine and finalize the
design. For these
conditions, the test
piles are generally
tested to failure.
115
116. EQUIPMENTS
Anchor Girder or Reaction Girders
Hydraulic Jack
Test Pile
Anchor Pile
Dial Gauges
Reaction Truss (in case of truss loading)
118. PROCEDURE:
• The set-up consists of two anchor piles provided with an
anchor girder or reaction girder at their top.
• The test pile is installed between the anchor piles as like
foundation pile is installed. The test pile should be at lest 3B or
2.5m clear from the anchor pile.
• The test is conducted after a rest period of 3 days after the
installation in sandy soils and period of one month in silts and
soft clays.
• The load is applied through a hydraulic jack resting on the
reaction girder or Truss. The measurement of pile movement
are taken with respect to a fixed reference mark.
• The load is applied in equal increment of about 20% of the
allowable load.
122. • Settlement should be recorded with 3 dial gauges.
• Each stage of the loading is maintained till the rate of
movement of the pile top is not more than 0.1mm per hour in
sandy soils and 0.02mm per hour in case of clayey soils as
maximum of two hours.
• Under each load increment, settlements are observed at 0.5, 1,
2, 4, 8, 12, 16, 20, 60 minutes.
• The loading should be continued up to twice the safe load or
the load at which the total settlement reaches a specified value.
• The load is removed in the same decrements at 1 hour interval
& the final rebound recorded 24 hours after the entire load has
been removed.
• Plot a graph of Load-Settlement and make a curve for loading
as well as unloading obtained from a pile load test.
124. Calculations
• Figure shows a typical Load-Settlement curve for loading as
well as unloading from a pile load test.
• For any given load, the net pile settlement (Sn ) is given by,
Sn = St- Se
Where ,
•St = Total settlement (gross settlement) Se = Elastic settlement
(rebound) Sn= net settlement
126. Micro piling:
• A micro pile is a small-diameter (typically less than 300
mm), drilled and grouted replacement pile that is typically
(up to 20% As/Ac) reinforced.
• A micro pile is constructed by drilling a borehole, placing
reinforcement, and grouting the hole. Micro piles can
withstand axial and/or lateral loads.
127. 127
HISTORICAL BACKGROUND
The use of micro piles has grown significantly since their
conception in the 195Os,
1952 - First introduced in Italy for foundation restoration
(underpinning) of WWII damaged buildings
1960’s – Widely used in Europe for underpinning old
sensitive structures
mid 70’s – First introduced in USA (New York &Boston)
1980’s – Being introduced in East Asia
128. 128
CLASSIFICATIONS OF MICRO PILE
1. Based on Design Application
2. Based on Grouting method
Based on Design Application
CASE 1 :- micro pile elements ,which are loaded directly
and where the pile reinforcement resists the majority of
the applied load.
CASE 2 :-micro pile elements circumscribes and
internally reinforces the soil to make a reinforced soil
composite that resists the applied load.
133. 133
Based on Grouting method
• The method of grouting is generally the most sensitive
construction control over grout/ground bond capacity .
Grout-to-grout capacity varies with the grouting
method.
1) Type A: Gravity Grout
2) 2) Type B: Pressure through Casing
3) 3) Type C: Single Global Post Grout
4) 4) Type D: Multiple Repeatable Post Grout
134. 134
Type A: Here the grout is placed under gravity head only
using sand-cement motors or neat cement .
Type B:
1) In this type neat cement grout is placed into the
hole as the temporary steel casing is with drawn.
2) 2) Injection pressures varies from 0.5to 1.0 MPa.
The pressure is limited to avoid fracturing of the
surrounding ground.
135. 135
Type C: This is done in two step process:
1) As of Type A
2) Prior to hardening of the primary grout, similar
grouts injected one time via a sleeve grout pipe at
pressure of at least 1.0MPa.
Type D: This is done in two step process of grouting
similar to Type C with modifications to step 2 where the
pressure is injected at a pressure of 2.0 to 8.0MPa.
