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Types of foundationS.Sai Teja

FOUNDATION:The foundations of the building transfer the weight of the building to the ground.They also refer to FOOTINGS.

Foundation

Shallow foundationDeep foundation

SHALLOW FOUNDATION:Shallow foundations are also called spread footings or open footings.Shallow foundations can be made in depths of as little as 3ft (1m).

DEEP FOUNDATION: Deep foundations can be made at depths of 60- 200ft (20 - 65m). Deep foundations are used for large, heavy buildings.

Deep foundations are again classified into many types. Let us consider the PILE foundation.PILE FOUNDATION:A pile is basically a long cylinder of a strong material such as concrete that is pushed into the ground so that structures can be supported on top of it.

Pile foundation:

DESIGN OF PILE FOUNDATION:

Pile foundations are used in the following situations:

Low bearing capacity of soil.When a building has very heavy, concentrated loads, such as in a high rise structure.

Non availability of proper bearing stratum at shallow depths.

Depending on their function, the different types of piles are:1. Bearing piles2. Friction piles.3. Sheet piles.4. Anchor piles.5.Batter piles.6. Friction piles.7.Compaction piles.

Compaction piles:

The piles which are driven in Granular soil, to increase the soil bearing capacity, are named as Compaction piles.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.

During the process of driving the pile into the ground, the soil becomes molded and, as a result loses some of its strength. Therefore the pile is not able to transfer the exact amount of load which it is intended to immediately after it has been driven. Usually, the soil regains some of its strength three to five months after it has been driven.

COMBINED END BEARING PILES:These piles transfer their load on to a firm stratumlocated at a considerable depth below the base of the structure.They derive most of their carrying capacity from the penetration resistance of the soil.

The load is transmitted to the soil through friction or cohesion. Sometimes, the soil surrounding the pile may adhere to the surface of the pile and causes "Negative Skin Friction" on the pile.Negative skin friction is caused by the drainage of the ground water.

Representation of End bearing and Compaction piles:

Differences between Compaction piles and End Bearing piles:A Compaction pile gets its bearing load mostly from friction, along the shaft.The End bearing pile gets its bearing load mostly form its resistance at itspile point, and normally these are very short piles.