Foundation is a basic part of any construction. it is made at the start of any construction .it is help the structure to transmit the structural load to the soil. in construction, there are different types according to the soil quality and surface of the earth.
so here I am going to discuss the foundation in construction, types of foundation and their uses in construction, the importance of foundation, the purpose of the foundation, and the process of the foundation, these are all basic knowledge for anyone, especially for civil engineers and if you are preparing for the interview this article will help you lots.
What is the foundation in construction?
Definition: it is defined as the enlargement of the base of any column and wall for transmitting the load of the structure to the soil is called the foundation. it the main element of any structure .without the foundation a structure will be unstable and can be fall.
In other words, the foundation is the main supporting component of any building structure. It is the lowest part of any structure which transmits the load to the supporting soil. The purpose of the foundation is to distribute the weight of the structure over a large area of soil.
Why is a foundation provided?
As we know the foundation is the main important part of any building and it should fulfill the same objectives
- Distribute the weight of the structure over the large area of soil
- Avoid the unequal settlement
- Prevent the lateral movement of the structure
- Increase the structural stability
Types of foundations in construction
Foundations are made in different types according to the surface of the earth as well as the capacity of soil .so foundations are classified into two main categories.
- Shallow foundation
- Deep foundation
Shallow foundation: a shallow foundation is a type of foundation in which the depth of the foundation is equal to or less than its width. it is situated below the lowest part of the structure.
These foundations are constructed where the soil layer is at shallow depth ( up to 1.5m ) and capable of supporting structural loads.
And according to the soil bearing capacity shallow foundations further classify into some categories
- Spread footing
- Combined footings
- Mat or raft foundation
- Isolated spread footing
- Cantilever or strap footing
Spread footings: for the wider area we used to construct spread floors which consist of a wide base of foundation for transmitting the structural load to the soil over the large surface or wider area.
Combined footings: this is provided to two columns which may be either rectangular or trapezoidal .it is consist of a common footing. that’s why it is called combined footings.
Raft foundation: raft foundation consists of a dense reinforced concrete slab that covers the total bottom area of any structure. it is provided in the soil with low bearing capacity where structural loads are heavy. for reinforcement, we use steel bars to provide good strength to the foundation.
The mat or raft foundation is economical when:-
- These types of foundations are used for low-bearing capacity soil
- These are for heavyweight structures
- It is recommended when compressed soil such as soft clay
Isolated spread footing: this is one of the simplest and most worldwide popular foundations. It is mostly used to support a single column.
At some points, it will be economical when
- The weight of the structure is comparatively less.
- Columns are not usually closely positioned
- The load carrying capacity of the soil is higher at shallow depth
There are the following types of isolated spread footing
- Single pad footing for a column
- Stepped footing
- Sloped footing
- Wall footing without step
- Stepped footing for walls
- Grillage foundation
Cantilever or strap footing: this type of footing is similar to the combined footings. It is economical when:-
- The column is located near the property line and its dimension is restricted.
- The column is constructed closer to each other.
Deep foundation: in this type of foundation the depth is much greater than its width. This foundation is placed at a deeper depth below the ground level.
Here also according to the earth’s surface, deep foundations are classified into some categories
- Pile foundation
- Cofferdams
- Caisson foundation
Pile foundation: in this type of foundation we used a slender member of wood or concrete or steel to insert into the ground for transmitting the load to the structure. The load is transferred to strong stratum friction .so here pile foundations are also classified into some categories according to the function and materials
Classification based on function
- Bearing piles
- Friction piles
- Sheet piles
- Anchor piles
- Batter piles
- Fender piles
- Compaction piles
Classification based on materials
- Timber piles
- Concrete piles
- Steel piles
When to use pile foundation
- When the groundwater table is high
- Heavy and un-uniform loads from the structure are imposed
- Other types of foundations are costlier or not feasible
- When the soil at shallow depth is compressible
- When the location of the structure is near the river bed or seashore etc
- When there is a canal or deep drainage system near the structure
Cofferdams: a cofferdam is a temporary structure that excludes the water from a given site and enables the construction on a dry surface .in this types different types of materials are used for making it so its also classified into some categories based on the materials.
- Earthen cofferdam
- Rock fill cofferdam
- Single walled cofferdam
- Double walled cofferdam
- Crib cofferdam
- Cellular cofferdam
Caisson foundation: caisson is a watertight structure made of wood, steel, or reinforced concrete that excavates for the foundation of bridges, piers, etc.
Types of caisson foundation
- Open caisson
- Box caisson
- Pneumatic caisson
FAQ
Ques :-1. What is the type of foundation?
Ans: shallow ad deep.
Ques:-2.what is the purpose of foundation?
Ans: to keep the structure stable.
Ques:-3.what is the standard size of the foundation?
Ans: the average minimum thickness of the foundation should be 200mm. the strength of the concrete used for the unreinforced footing strips should be 15MPa.
Ques:4. What foundation type is best for the house
Ans: which is made of concrete.
Ques: 5. How much thickness should a slab foundation
And: it should be 4” to 6”
Ques:6. What is the minimum depth of foundation?
Ans: as per IS:1904 it should be at least 50cm below the natural ground level
Ques:-7. What is the difference between foundation and footing?
Ans: the foundation is a structure that transfers the load from the superstructure to the soil, while footing is the foundation that is in contact with the earth.
