Hello friends welcome all of you to our blog. Today we are going to talk about Foundation. Hope you can understand easily.

What is the Foundation ?

Foundation is the lowest part of a structure below the ground level which is in direct contact with ground and transmits all the loads to the ground. Majority of structure fails due to failure of their foundation. 



       To build the foundation, we usually dig trenches in the ground, digging deeper and deeper until we come to the sub-ground, which can be compared to the topsoil used for growing plants and crops. Is more solid. When the trench is deep enough, we fill it with any strong, hard material we can find. Sometimes we pour concrete into the trench, which we first reinforce by inserting long thin round pieces of steel into the trench. When the concrete dries, the steel acts like the bones of our body, holding the foundations together. We call it reinforced concrete.


Purpose of  Foundation

1) To distribute the load of the structure over large area so as to bring down the intensity of load at its base below the safe bearing capacity (S.B.C.) of sub soil.
2) To support the structures.
3) To distribute the non-uniform load of the superstructure, uniformly to the sub-soil. 
4) To provide a level and hard surface for concreting and masonry work. 
5) To take the structure deep into the ground and thus increase its lateral stability, preventing overturning. 
6) To load the sub-stratum evenly and thus prevent unequal settlement.

             
If your question was, that what is a foundation and what is it types, then you have seen about foundation, then now let's see about the type of foundation.


Types of Foundation

There are two  types of foundation, one is shallow foundation and the second is Deep foundation.

1) Shallow Foundation

If depth of footing is less than or equal to the width of footing, it is called shallow foundation. 

D≤ B

  • Shallow foundation is provided when bearing capacity of soil is more and required bearing capacity is available at shallow depth. 
  • It is provided when load of the structure is less.
  • It is suitable when timbering to the trenches is possible.
  • It is suitable when ground Water Table (W.T.) is low. 
  • It is suitable when top layers of soil are uniform and stable.
  • It is suitable when dewatering of foundation is not required. 
  • Types of shallow foundations are, 
                         1) Spread footing 
                    2) Combined footing 
                    3) Strap footing 
                    4) Raft foundation
                    5) Grillage foundation


2) Deep Foundation 

If depth of footing is more than the width of footing, it is called deep foundation. 

D > B 

  • Deep foundation is provided when bearing capacity of soil is low or desired bearing capacity is available at more depth. 
  • It is provided when load (weight) of the structure is more. 
  • It is suitable when timbering to the trenches is costly or impossible. 
  • It is suitable when ground water table is high. It is suitable when top layers of soil are non- uniform and unstable. 
  • It is suitable when dewatering of foundation trenches is costly and difficult.
  • Types of deep foundations are,
                   1) Pile foundation 
                   2) Cassion or well foundation 
                   3) Coffer dams.