Foundation is often referred to as a substructure of a building. Foundations transfer the load coming from the superstructure safely to the beneath soil. Here types of foundations and their use cases are described.
We can classify foundations into two broader types-
- Shallow foundation
- Deep foundation
Shallow Foundations And Their Types
It is one, in which the breadth to depth ratio is more than two. Shallow foundations are suitable where loads coming from the structure is less or it is also preferable where firm ground strata are available at shallow depth.
The following are some types of shallow foundations.
Isolated column footing:
It is used under a single column. The shape of the column may be circular, square, rectangular or even complex like ‘L’ shaped or ‘T’ shaped. There are two subtypes of this type of footing.
In this type, the footing gets battered shape.
This type of footings resemble the shape of steps.
This type of footing is adopted when there is one column near the property line or it may be adopted when the two columns are very near each other such that separate footing is not possible.
It could also be subdivided into two types.
Rectangular combined footing
This type of footing is adopted where there are two columns are adjacent to each other and it is not possible to provide single column footing.
Trapezoidal combined footing
When one column has more load intensity on it another one has to carry a lower load then this type of foundation is provided.
This type of foundation is also known as mat foundation and these are suitable in case black cotton soil.
Steel grillage footing:
Steel grillage foundation is a type of shallow foundation. This type of foundation is most suited for steel columns. Also, steel grillage foundation construction needs skilled labor.
As per Coulomb, if for a foundation the depth to breadth ratio exceeds 2, then it may be classified as deep footing.
When firm ground strata are not available at shallow depth, the engineer may need to go deep in the ground to place the foundation. The various type of deep foundations are pile foundations, caissons, under-reamed pile foundations, fenders, precast piles etc.
Following are the types of deep foundation
Pile foundation is used where loading from the superstructure is very heavy or beneath soil has a poor bearing capacity. There are many types of pile foundations. You can get details about the pile foundation here types of pile foundation
These types of foundation are adopted for bridges. This type of footing is also known as caissons.
Other relevant articles
Types of Pile foundation used for building consruction
Types of caissons used for foundation of bridges
Geotechnical Engineering Interview Questions
You can also pursue free course on foundation engineering by NPTEL with following link.
NPTEL course on foundation engineering
Most Useful Books For Geotechnical Engineering
Frequently Asked Questions
What is a floating foundation:
A floating foundation is a type of foundation which do not impart any additional load to the soil beneath the foundation. The weight of the soil excavated to place the foundation is same or more than the weight of the building to be constructed.