A foundation (footing) provides a critical interface between a structure and ground beneath it; Its basic function being to transfer the loads through the structure to the supporting rock/soil. It the main part of the building on which the load of the whole structure transmits and it is properly designed.
Types of Foundation:
The various type of structural Foundation are grouped into two categories
It transmits structural load to the soil strata at the relatively small depth. As an approximate criteria terzaghi (1943) define shallow foundation as one which is laid at depth Df not exceeding with B of footing
i.e Df/ B < 1
A shallow may be defined as one in which the embedment depth of the footing is less than its characteristics.
When the ration between Df(Depth of footing) / B (Width) greater 1 but less than 15 is moderately deep. Deep foundation such as pile foundation have Df/B ratio greater than 15.
Compression of Shallow & Deep Foundation
|Constructed in open excavation||Mostly buried in soil|
|Disturbance of soil is minimum||Disturbance of soil extend to large extent|
|Economical structure||Costly structure|
|Load is directed to the soil||Load is supported partially by friction resistance & rest by bearing at the base of foundation|