- Foundation⇒ is the supporting base of a structure that transmits the load from the structure to the Natural ground and takes reaction back.
- Shallow Foundation⇒ If D/B<1, i.e if the depth of the foundation is less than the width of the foundation than foundation is considered to be Shallow.
- Spread/Pad Footing⇒ Used for single Column
- Strip Footing⇒ Used to support the wall.
- Mat/Raft Foundation⇒ It is a single slab covering the total area. If the spread footing or strip footing is covering more than 50% area and bearing capacity of the soil is low than Raft footing is used to cover the entire area. It reduces the differential settlement.
- Combined Footing⇒ these footings are usually constructed due to space limitation, and support two or more columns.
- Floating Foundation or Compensated Foundation ⇒if a raft, is placed at such a depth that the intensity of imposed loading due to structure and foundation does not exceed or become less than the initially existing pressure at the depth prior to excavation.
All the foundation should extend to a minimum depth of 50cm below the natural ground level (IS-1904) to save the foundation from the environmental effect.
Two important factors that are to be considered are
- The foundation must be stable against the shear failure of the supporting soil.
- The foundation must not settle beyond a tolerable limit to avoid damage to the structure.