Foundation and Its Various TypesTweet
Foundation and Its Various Types
Superstructures are those structures which are above ground and visual like dams, bridges, buildings, roads etc. These structures apply load on the soil once they rest. Therefore, if superstructures are placed in direct contact with the soil it'll cause the soil getting overstressed and can not be ready to provide a secure support. So on allow the safe transfer of the load of structure on soil certain a part of the structure are made to be placed under the bottom .
The structure which is placed in below the bottom is named the sub-structure. Therefore, structural elements which help in connecting superstructures like bridges, buildings etc. to the bottom are referred to as foundations. the inspiration plays an important role for each structure because the safety and reliability of the structure depends highly on the inspiration .
From the superstructure to the sub-structure the load is transmitted. the inspiration helps in distributing the load to the soil in such how that the soil is in a position to face up to the load.
Types of Foundations:
1. Shallow Foundations
Foundations which helps in transmitting the load to soil at a shallow depth it's referred to as shallow foundations. A shallow foundation is employed in places where the shallow depth has the capacity to carry the structure and therefore the load that's placed thereon . within the case of shallow foundations, the ratio of the depth of foundation to the width of foundation is a smaller amount than or adequate to 1. samples of shallow foundations- spread footing and mat.
2. Deep Foundations
Foundations which help in transmitting the load to deeper soil is understood as deep foundations. When the soil at shallow depth is unable to require the load and a tough stratum is found at a bigger depth that's when deep foundations are used. just in case of deep foundations, the ratio of depth of foundation to the width of foundation is quite 1. samples of deep foundations- piles and caissons.
Given below is that the list of the varied sorts of shallow foundations:
A. Spread Footing
It is also referred to as individual column footing. The spread footing shape is usually that of the column, it are often square, rectangular or circular. ferroconcrete is employed to form it. the rationale why it's called spread footing is because it spreads the load of the structure over a particular area of the soil.
B. Strap Footing
Strap footing is when the isolated spread footings of two column is formed to attach by a beam. The beam during this case is named strap beam. No load is transferred to the soil by the strap beam because it isn't in any contact with the soil.
C. Combined Footing
Combined footing is when a selection footing is supported by two or more columns. the development of combined footing takes place when two or three columns are located on the brink of each other . just in case "> just in case the 2 columns carry equal load then the form of combined footing are going to be rectangular and in case they each carry different loads then it maybe trapezoidal in shape.
D. Continuous Footing
Strip footing is that the other name of continuous footing. For a load wall continuous footing is employed . Bricks are wont to make continuous footing. In continuous footing, the length is far longer than the width of the footing.
E. Mat or Raft Footing
Mat footing is when endless footing is in a position to hide the whole area below the structure of walls and columns. Mat footing is a cheap option if quite 50% of the building’s plan area is roofed by combined by area of isolated footing.As mat footing is structurally rigid and settles uniformly as a monolithic entity due to which the probabilities of differential settlement is a smaller amount . this sort of footing is chosen when the soil conditions is extremely erratic and therefore the structures are heavy for spread footing to carry .
What affects the depth of shallow foundations?
Thickness of top Layer: the inspiration is to be placed below the thickness of the organic matter which could contain an honest percentage of vegetables and other organic decaying matter. this is often because the soil undergoes a shift in volume by the location of external load.
Ground Freezing: Shallow foundations is suffering from ground freezing which takes place when the air temperature goes below 0◦C which results in a drop by the temperature of the soil which turns the pour water into ice. The formation of ice underground creates an upward movement of ground which is named ice lens. it's important to put the foundations below the depth of frost penetration so on avoid any damage to the structure.
Depth of volume change: thanks to alternate wetting and drying the soil can undergo volume changes, for instance within the case of black cotton soil. Therefore, in such cases the inspiration must be placed below the world of volume change.
Depth of scour: it's important to think about the depth of scour in cases where the structure is adjoining rivers or streams where the structure is faced with the scouring action of water. The depth of the inspiration should be, therefore, below the potential scour depth.
Underground utilities and defects: When the choice of depth of foundation is taken the underground facilities must be kept in mind. it's also important to think about underground defects like cavities, abandoned mines etc. also while planning for the inspiration .
Property line and adjoining structures: it's extremely important to stay in mind that the inspiration where located must not extend itself to the adjacent boundary line which may cause legal disputes. just in case a replacement foundation is to be laid near an existing structure, a minimum distance must be maintained faraway from the old structure.
Sloping ground: just in case of a sloping ground where the inspiration must be laid then the depth of foundation must be such if a line id drawn from rock bottom fringe of the inspiration at an angle of 30◦ and from a horizontal distance of 90cm then they need to not intersect.
Types of Deep Foundations:The various sorts of deep foundations depending upon mechanism to shape and its material are stated below:
Pile Foundation A long and slender structural element which is in a position to transfer the load of a structure from firm stratum to an excellent amount of depth below ground surface is named pile foundation.
Pier FoundationThe large diameter piles which may distribute the load of the structure along the entire depth of soils where it's located is named pier foundation.
Well or Caisson Foundation A large size hollow box or well which is formed to drown into the bottom so on support heavy loads are the well and caisson. they will carry sizable amount of loads. With end bearing and skin friction they transfer the load from the superstructures to the soil. These foundations are usually utilized in bridge.