A foundation is an integral part of the structure that transfers the load of the superstructure to the soil. 

A foundation is the member that provides support for the structure and it is loaded. It consists of soil and rock of the earth's crust and any particular part of the structure that serves to transmit loads to rock or soil.

Foundation is the basic thing that is important for all sort of construction works all over the world.

There are two types of foundations that are: 



Requirement Criteria:- 

If the soil conditions immediately below the structure are sufficiently strong and capable of supporting the required load, then shallow spread footings can be used to transmit the load.

On the other hand, if the soil conditions are weak, then piles or piers are used to carry the loads into deeper, more suitable soil.

1. Shallow foundations:

where the depth of the footing ( Df )is generally less than the width (B) of the footing. 

Design Consideration:

Must not settle excessively.

The surface should be kept at a sufficient depth to prevent damage from environmental impacts (frost,erosion and scouring,swelling and shrinkage).

Failure to support the soil should not be the cause (Bearing capacity criterion). 

Advantages of using shallow foundations:

Material (mostly solid).

Labour (Specialization not required).

Cost (affordable).

Manufacturing process (simple).

Disadvantages of using shallow foundations:


Irregular ground surface (slope, retaining wall).

The Foundation subjected pullout, torsion, pall.

2. Deep foundations :

where the depth of the footing 
( Df ) is greater than the width (B) of the footing . 

However when we are considering large structures, which carry heavy loads, the loads are dissipated at greater depths where usually the soil bearing capacity is quite high.

Requirement for Deep Foundations:

Generally for structures with load >10 
t/㎡, we go for deep foundations. Deep foundations are used in the following cases:

  • Massive vertical load in relation to soil capacity.
  • Very weak soil or problematic soil.
  • Huge lateral loads e.g. Tower, Chimney.
  • Depth criteria.(scouring depth).
  • When there is great depth to fill.
  • Regeneration condition (expansion zone).
  • Urban areas for future large and huge construction near existing building.


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