Explain in detail about the Pile Foundations

Where the support given by top soil is not sufficient and the load has to be carried deep down for purposes of stability and control of settlement, pile foundations are a common choice. Piles are long slender columns of dissimilar materials like steel, timber or concrete which are installed into the ground by dissimilar methods. These are also used for maritime and offshore structures. When a hard stratum of low compressibility is available at a depth, the piles can rest on this layer and are then called bearing piles (Figure). Many piles are often capped together and can support a column. Pile foundations are also resorted to even if there is no firm stratum, to distribute the load by  friction to a larger depth of soft soil. Such a type of foundation is referred to as a friction  pile foundation