PILE FOUNDATION BY-

FOUNDATIONS Foundations are structural components used to support columns and transfer loads to the underlying Soil. Foundations Shallow Deep Isolated footing Combined footing Strap footing Wall footing Raft footing Caissons Pile

PILE FOUNDATION Pile foundations are the part of a structure used to carry and transfer the load of the structure to the bearing ground located at some depth below ground surface. A pile is a slender structural member made of steel, concrete or wood. A pile is either driven into soil or formed in-situ by excavating a hole and filling it with concrete.

FUNCTION OF PILES As with other types of foundation, the purpose of a pile foundation is: To transmit a foundation load to a solid ground. To resist vertical, lateral and uplift load . Piles can be Timber Concrete Steel Composite

NECESSITY OF PILE FOUNDATION When the strata below the ground surface is very weak to support load transmitted by the structure. For the transmission of structural loads through deep water to a firm stratum. Where the soil is water-logged. When stratum of required bearing capacity is at greater depth. When the soil is highly compressible.

CAUSES OF FAILURE OF PILES Load on the pile is more than the designed load. Displacement of reinforcement during casting. Bearing pile resting on a soft strata. Improper choice of the type of pile. Insufficient reinforcement in the pile. Decay of timber piles due to attack by insects. Buckling of piles due to inadequate lateral support. Defective method adopted for driving the pile. Incorrect assessment of the bearing capacity of the pile. Lateral forces not considered in the design of piles.

FACTORS AFFECTING SELECTION OF PILES Physical properties of the soil at the site. Depth to a stratum capable of supporting the piles. Possibility of variations in the depth to a supporting stratum. Availability of materials for piles. Number of piles required. Facilities for driving piles. Comparative costs in place. Types of structures adjacent to the project.

CLASSIFICATION OF PILES Based on material Based on method of construction / installation Based on mode of transfer of loads Based on use Based on displacement of soils

CLASSIFICATION BASED ON MATERIAL Concrete Piles Steel Piles Timber Piles Composite Piles

CLASSIFICATION BASED ON METHOD OF CONSTRUCTION Driven piles Driven and cast-in-situ piles Bored and cast-in situ pile Jacked piles

CLASSIFICATION BASED ON MODE OF TRANSFER OF LOADS End bearing piles Friction/Floating piles Combined end bearing piles

CLASSIFICATION BASED ON USE Load bearing piles Compaction piles Tension piles Sheet piles Fender piles Anchor piles

CLASSIFICATION BASED ON DISPLACEMENT OF SOILS Displacement piles Non-displacement piles

LOADS APPLIED TO PILES Combinations of vertical, horizontal and moment loading may be applied at the soil surface from the overlying structure. For the majority of foundations the loads applied to the piles are primarily vertical. For piles in jetties, foundations for bridge piers, tall chimneys, and off-shore piled foundations the lateral resistance is an important consideration. H V M

PILE DRIVING METHODS Drop hammer Steam-hammer Boring Screwing Water jet

DROP HAMMER Hammer is raised by a rope or a steel cable. Then it is allowed to drop on pile cap. The weight of drop varies from 230-1800 kg. Weight depends on the shape and length of pile and the nature of the ground. Takes a lot of time.

DROP HAMMER METHOD

STEAM HAMMER A heavy hammer is dropped on to the pile through a small height but in quick succession. A steam cylinder and piston is used. Steam pressure and the rate of hammer blows are kept uniform. Steam hammers are of two types: Single Acting type Double Acting type

BORING Sometimes, piling is done by boring holes of suitable diameter to the required depth and then dropping piles in them. Generally cast-in-situ piles are laid by this method. SCREWING Screw piles and disc piles are generally driven by this method. They are driven into the ground by turning them round and round in one direction with big levers.

INSTALLATION BY BORING

WATER JETS Pile driving can also be done displacing the material at or near the foot of the pile by means of one or more water jets under pressure. Sometimes, hammer may be used to force the pile rapidly into the ground. The pressure of the jet should be sufficient to displace the soil for driving the piles quickly and satisfactorily.

ADVANTAGES OF PILE FOUNDATIONS Provides a common solution to all difficult foundation site problems. Can be used for any type of structure . Can be used in any type of soil. Now-a-days pile foundation is vastly in use instead of well and caisson foundation.

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