This document provides information on pile foundations, including when they are used, their functions, types, and construction methods. Pile foundations are used when the soil at shallow depths does not have adequate bearing capacity. The key points are: - Pile foundations transmit loads from structures to deeper, stronger soil layers through end bearing, friction, or both. - They are used when shallow soils cannot support heavy loads, have low bearing capacity, or experience issues like high water levels. - Piles can be made of concrete, timber, steel, or composites, and are either pre-cast or poured in place. Common types include end bearing, friction, compaction, and anchor piles.

1. Gaurang Kakadiya
Piles

2. Introduction
 Pile foundation is a type of deep foundation. It is used where foundation work
is not possible by ordinary method of open pit excavation.
 Pile foundation is one type of deep foundation. It is used where the good soil is
at higher depth (10 or 15 m) or soil having low bearing capacity. Pile is also
used for tall structures. In pile foundation load coming from the super structure
is taken by pile cap and equally distributed in no. of piles. Pile transfers this
load in to the soil.
Following are the situation in which a pile foundation are used:
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.
Function of piles
As with other types of foundations, the purpose of a pile foundations is:
 to transmit a foundation load to a solid ground
 to resist vertical, lateral and uplift load
A structure can be founded on piles if the soil immediately beneath its base does not have
adequate bearing capacity. If the results of site investigation show that the shallow soil is unstable
and weak or if the magnitude of the estimated settlement is not acceptable a pile foundation may
become considered. Further, a cost estimate may indicate that a pile foundation may be cheaper
than any other compared ground improvement costs.
In the cases of heavy constructions, it is likely that the bearing capacity of the shallow soil will
not be satisfactory, and the construction should be built on pile foundations. Piles can also be used
in normal ground conditions to resist horizontal loads. Piles are a convenient method of foundation
for works over water, such as jetties or bridge piers.
Classificationofpiles basedon function:

3. (1)End bearing piles :
These piles are used to transfer the load through water or soft soil of ground to a
suitable hard bearing stratum.
(2)Friction piles:
These piles are used to transfer loads to a depth of a friction load carrying material
by mean of a skin friction along the length of piles
(3)Compactionpiles:

4. 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’.
(4)Tensionor Uplift piles:
These piles anchor down the structure subjected to uplift due to hydrostatic pressure
or due to over-turning moment.

5. (5)Anchor piles:
These provide anchorage against the horizontal pull from sheet pulling or any other
pulling.

6. (6)Fender piles:
These are used to protect water from structure against impact from ships or other
floating objects.

8. (7)Sheetpiles:
These pile are used as a impervious cut off sheet to reduce seepage and uplift under
hydraulic structure

10. (8)Batterpile:
These piles are used to resist large horizontal or inclined forces

11. (9) Cohesionpiles:
These piles transmit most of their load to the soil through skin friction. This process
of driving such piles close to each other in groups greatly reduces the porosity and
compressibility of the soil within and around the groups. Therefore piles of this category are
sometimes called compaction piles. During the process of driving the pile into the ground,
the soil becomes moulded and, as a
CLASSIFICATION BASED ON MATERIAL AND COMPOSITION:
1. CONCRETE PILES
(a) Pre-cast
(b) Cast-in-situ
(i) Driven Piles: Cased or Uncased
(ii) Bored Piles: pressure piles, under reamed piles and bored compaction piles.
2. TIMBER PILES
3. STEELPILES
(a) H-pile
(b) Pipe pile
(c) Steel pile
4. COMPOSITEPILES
(a) Concrete and Timber
(b) Concrete and Steel

12. 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 upto 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.
PROCEDUREFOR FORMINGPRECASTCONCRETE 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.

13. DISADVANTAGE OF PRECAST CONCRETEPILES:
 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 CONCRETEPILES:
 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.
CAST-IN-SITU CONCRETE PILES:
 The cast-in-situ concrete piles are generally used for maximum design load of 75 tonnes.
 They are installed by pre-excavation, thus eliminating vibration due to handling stresses.
There are two types of cast-in-situ concrete piles:

14. (1) DRIVEN PILES (CASED OR UNCASED)
(2) BORED PILES (PRESSURE PILES, BORED COMPACTION AND UNDER-REAMED
PILES)
(1) CASED –IN-SITU CONCRETE PILES:-
 This method is practically suitable for all type of ground condition.
 Shell is driven into intimate contact with the surrounding soil and remains in place to
maintain driving resistance and protect the concrete filling during the place of other adjacent
piles.
 Cased pile can be easily cut or extended to meet the variation in shell length.
FOLLOWING ARE THE COMMONE TYPE OF CASED CAST-IN-SITU CONCRETE PILES:
(1) Raymond standard pile and step-taper pile
(2) Mc-Artuhr cased pile
(3) Swage pile
(4) Western button bottom pile
1. RAYMOND PILES:
 (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.

15.  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.
(RAYMOND STEEP TAPER CONCRETE PILE)
 This type of core driven pile is used either as an end bearing pile.
 Can be driven in any type of soil.
 The pile uses shell section in different length. The bottom most section is made of heavier
gauge and enclosed with flat steel.
 Joints between the sections of shell are screwed and connected.
 Shell are driven with a rigid core, rigid core provides high degree of penetration and
efficiently transmit the hammer energy to the bearing strata.
 The pile diameter increases at rate 2.5cm in each successive shell section.
 Pile can be drawn upto maximum depth of about 36m.
 The method of forming piles is same as of standard pile.
Mc ARTHUR CASED PILE:
 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.
 There are four stages of forming these piles.
 First stage: thin shell with steel core not easily fitted over the pre casted concrete plug is
first inserted to plug such that plug gets fixed in the shell.
 Second stage: pipe is driven over the plug till the core reaches the plug and forms water
tight joint.
 Third stage: pipe is driven upto desire depth. Driving force is applied by core on plug, Pipe
is pulled down rather than driven.
 Fourth stage: when the pipe reached to desired depth, the core is removed and the pipe is left
open for filling the concrete.
 These piles are used in place where increase in the end bearing area is needed.
 Pre casted concrete button shaped plug is fitted at end of pipe are used, as this button forms
the enlarged hole in the soil during pipe driving.
 Side friction is reduced. These piles are used upto depth of 23m, for load of about 50 tonnes.
 First stage: steel pipe having 12mm thickness and reinforced base is fitted over the concrete
plug.
 Second stage: the pipe and button driven upto desired depth.

16.  Third stage: corrugated steel shell is inserted in the pipe, resting on button. Steel plate with a
bolt hole in it is welded on the bottom of the shell, before lowering it, so that the hole may
fit over the central bolt in button.
 Nut is tightened with the help of long wrench.
 Fourth stage: casing is removed, leaving the button in place, and the shell is filled with
concrete.