Substructure or foundation is a part of the structure, usually placed below the ground surface and transfers the load to the underlying soil or rock.
If different parts of a structure are subjected to different settlement. This is known as differential settlement.
Different amount of settlement within same structure is known as differential settlement.
Differential settlement in a structure is more undesirable than the total settlement or uniform settlement. Because it causes more damage to the structure as compared to the uniform overall settlement of the structure.
Limitation on uniform total settlement
To limit the settlement it is necessary
- To transfer the load of structure at a layer which is strong enough in bearing capacity.
- To spread the load over a sufficiently large area to minimize the bearing pressure.
Two essential requirements of foundation design
Two essential requirements of foundation design are
- Total settlement should be limited to small amount.
- Elimination of differential settlement as nearly as possible.