Foundation and it's types

                                       foundation

A foundation (or, more commonly, foundations) is the element of an architectural structure which connects it to the ground, and transfers loads from the structure to the ground. Foundations are generally considered either shallow or deep.Foundation engineering is the application of soil mechanics and rock mechanics (Geo technical engineering) in the design of foundation elements of structures

types of foundation

1)shallow foundation:- 

 Shallow foundations are also called spread footings or open footings. The 'open' refers to the fact that the foundations are made by first excavating all the earth till the bottom of the footing, and then constructing the footing. During the early stages of work, the entire footing is visible to the eye, and is therefore called an open foundation. The idea is that each footing takes the concentrated load of the column and spreads it out over a large area, so that the actual weight on the soil does not exceed the safe bearing capacity of the soil.

2)strip footings:-

Strip footings are commonly found in load-bearing masonry construction, and act as a long strip that supports the weight of an entire wall.  These are used where the building loads are carried by entire walls rather than isolated columns, such as in older buildings made of masonry.

3)Raft Foundations:-

Raft Foundations, also called Mat Foundations, are most often used when basements are to be constructed. In a raft, the entire basement floor slab acts as the foundation; the weight of the building is spread evenly over the entire footprint of the building. It is called a raft because the building is like a vessel that 'floats' in a sea of soil.

Mat Foundations are used where the soil is week, and therefore building loads have to be spread over a large area, or where columns are closely spaced, which means that if individual footings were used, they would touch each other.

4)PILE FOUNDATIONS:-

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.