INTRODUCTION OF REINFORCED EARTH:-
Reinforced Earth structure consists of compacted soil mass within which reinforcing elements are embedded. The reinforcing elements or membranes might be either in the form of geo textile usually in the form of horizontal strips.
The main job of the reinforcement is to provide strength to the soil to take the tensional forces. By means of friction, reinforcing elements develops strength to provide reinforcement to take the tensile forces. Friction will be developed between the compacted soil layers and the reinforcing elements, due to which tensile forces can be handled.
Henry Vidal developed the modern day version of reinforced earth structures in France in 1968. This technique is held and jointly was developed by this sceintist along with “REINFORCED EARTH” company. The company name is having the same name as that of the concept, but should not be confused with the original name.
PRINCIPLES OF REINFORCED EARTH:-
The basic principles of using reinforcing materials in soil mass is, just very similar to that of using steel in concrete as a reinforcement.
- Membranes are used to provide reinforcements.
- Reinforcing membranes takes up the tensile forces.
- Reinforcing elements provide tensile strength in the earth mass where shear stresses are generated.
- Provision of membrane leads to redistribution of stresses internally within each of the membrane encapsulated layers.
- The reinforced Earth structure principle is essentially based in the mobilization of interfacial shearing resistance between soil and reinforcement.
Reinforced earth wall:-
The main application of reinforced earth structure is the reinforced earth wall. It consists of:-
- Wall facing elements.
- Reinforcing elements.
- Compacted backfill/earthfill.
Wall facing elements:-
Wall facing elements are provided at the free boundary of the reinforced Earth structure, So as to ensure that the soil is contained. These substances should be strong enough to hold the soil mass. These wall facing elements are usually made up of glass, fibers, plastic, aluminium, steel, or reinforced concrete, etc. They require a small reinforced concrete Foundation.
The reinforcing elements might consist of the following:-
- Galvanized steel strips
- Galvanised Steel rods
- Other metals Strips
The soils used in the compacted backfill must be predominantly coarse in size specifically saying 90% of the soil must retain in 63 micron sieves. First layer of the soil is placed on the ground level and then reinforcement layers are added and again soil layer is placed, like this consecutively each layers are placed up to the height of the wall. It is very necessary to ensure that the soil is adequately drained to prevent it from becoming saturated.
ADVANTAGES OF REINFORCED EARTH:-
- They are highly flexible and hence they can with stand deformations or settlements.
- Since they are flexible they can also which stand the earthquake forces.
- There are quite economical as compared to the conventional structures of masonry or concrete.
- They can be easily transported, and hence it can increase the speed of construction.
- Reinforced earth structures can be constructed in stages.
- Reinforcing elements are available in various sizes and shapes.
APPLICATION OF REINFORCED EARTH:-
Various applications of using reinforcement for tensile forces in soils are as follows:-
- Use in Bridge works
- Root file system
- Waterways structure
- Underground structures.