A pile is basically a long cylinder of a strong material such as concrete that is pushed into the ground to act as a steady support for structures built on top of it. Pile foundations are used in the following situations:  When there is a layer of weak soil at the surface. This layer cannot support the weight of the building, so the loads of the building have to bypass this layer and be transferred to the layer of stronger soil or rock that is below the weak layer.  When a building has very heavy, concentrated loads, such as in a high rise structure, bridge, or water tank.

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Pile Foundation
A pile is basically a long cylinder of a strong material such as concrete that is pushed into the
ground to act as a steady support for structures built on top of it.
Pile foundations are used in the following situations:
 When there is a layer of weak soil at the surface. This layer cannot support the weight of
the building, so the loads of the building have to bypass this layer and be transferred to
the layer of stronger soil or rock that is below the weak layer.
 When a building has very heavy, concentrated loads, such as in a high rise structure,
bridge, or water tank.
Pile foundations are capable of taking higher loads than spread footings.
Figure: Pile Foundation

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Figure: Bearing Pile and Friction Pile
Figure: Sheet Pile
Figure: Anchor Pile, Fender Pile, Batter Pile

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Timber Piles (Load ≤ 20 ton normally, lower end pointed)
Timber Piles: Transmission of load through timber piles takes place by the frictional resistance
of the ground and the pile surface. Timber piles prove economical hit supporting light structures
to be located in compressive soils constantly saturated with water. The timber piles are made
from timber obtained from trees like sal, teak, deodar, babul, Khair etc.
Advantages:
 Economical and available in market.
 Can be driven rapidly.
 Elastic (for lateral forces).
 Do not need heavy machinery.
Disadvantages:
 Restricted Length.
 Low bearing capacity.
 Susceptible to GWT (Dry &Wet season).
 Decay by salt water/attack by insect.
 Can be injured during drive.
Figure: Timber Pile And Lower Part of Timber pole

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Steel Piles:
Advantages:
 Normally 30 ft length is available. If exceeds welded at the joint.
 Produce very small soil displacement
 Penetrate through a rock or through hard substratum.
Disadvantages:
 Since corrosion is the main problem for steel, so required to coat with coal tar or some
other types to prevent corrosion.
Other types of steel piles are:
 Pipe piles (like steel pipe)
 Screw piles (may be hollow or solid, helix or screw base)
 Disc piles (disc at bottom to increase bearing area, inserted in sandy soil by water jets)

Figure: Pipe Piles, Screw Piles, Disc Piles
Concrete Pile
Advantages:
 Durable (independent of GWL)
 Could be of any length, size, shape.
 No. of piles required is less due to greater bearing power.
 No corrosion.
 Materials available.

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Disadvantages:
 Cost > timber piles
 Must be reinforced to withstand handling stress
 Elaborate technical supervision and heavy driving machine required
 For precast, require space and carrying cost.
Pre-cast piles (Driven Piles):
Pre means before & cast means made. So precast pile refers to a pile that has made before it is
being used.
Figure: Pre-cast Piles
Types of
Concrete Pile
Pre-cast piles
(Driven Piles)
Cast-in-situ piles
(Bored Piles)
Prestressed
concrete piles

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Why andWhere?
 Pre cast pile isusedforextraheavyweightstructure becauseitcanensure full strengthby
propermaintaining.
 It can be usedunderwater.
Figure: Pre-cast Pile
Shape:
 Circular
 Square
 Octagonal
Figure: Octagonal, Circular, Square Piles

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 Construction Step by Step:
1. Polythene Layer and Shuttering
2. Clear Cover
3. Reinforcement

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4. Shoe
5. Concreting
6. Vibrating

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7. Leveling
8. Curing
Advantages:
 They can be cast will before the commencement of the work resulting in rapid
progress of work.
 Their construction can be wellsupervised and any defect detected can be rectified
before use.
 The reinforcement remain in their proper position and do not get displace.
 They can be drive under water.
 They can be loaded soon of they have been driven to the desire depth.

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Disadvantages:
 They are heavy and great difficulties experienced for their handling and transporting
 They are subjected to the driving after the concrete has fully set. This may result in
unsound construction.
 Pre-cast pile cannot be long.
 Pre-cast pile shake that can harm other structure.
Piles are driven in the ground by the following method:
 By drop hammer.
 By steamhammer.
 By water jet.
 By boring