The document describes how soil reinforcement works. Tensile elements are placed in the soil to improve its strength and stability. When pressure is applied, it causes strain on the reinforcement elements, creating tensile loads that resist soil movement. This provides greater shear strength than soil alone. The reinforcement interacts frictionally with the soil to resist shear stresses, transferring loads from the soil. If tensile or pull-out failures occur, the stability is examined. Common reinforcement materials include strips, sheets, grids and geosynthetics made of polymers, steel or natural materials.

1. How is it done?
• Soil is reinforced by placing tensile elements in the soil
to improve its natural strength and stability.
• This is accomplished by comprising reinforcement
elements with surfaces in the aggregate and sub-base of
soil mass.
• When pressure is applied on the soil mass, it causes a
strain on the reinforcement, creating a tensile load
which can now resist soil movement and provide
additional support.
• By doing this, soil is reinforced and provides much
greater shear strength than the soil mass alone.

2. Load Transfer Mechanism
• The flexible reinforcement interacts
frictionally with the soil resisting the
shear stresses in the soil mass.
• The shear stress at the interface of the
soil and the pressure generates strains
in the reinforcement and a tensile force
is mobilised in the reinforcement.
• If this tensile force exceeds the tensile
capacity of the reinforcement, rupture
failure occurs – Tensile failure.
• If deformations are high or if the
interface is smooth, it is likely that a
slip occurs between the soil and
reinforcement – Pull-out Failure.
• For stability, Tensile failure and Pull-
out failure to be examined
stresses are transferred from the soil to the
reinforcement by the friction and/or passive
resistance

3. Principle
• If a vertical stress (σv) is applied on a soil element, it undergoes a
vertical compression (σv) associated with lateral deformation (σh).
• If a reinforcement is added to the soil in the form of horizontal
layers, the soil element will be restrained against lateral
deformation as it acted by a lateral force.
• These forces induce an increase of confining pressure in the soil in
the direction parallel to the reinforcement, thus restricting the
lateral strains of the soil

4. Experimental Demonstration on Principle of Mechanically
Stabilised Soil

5. Materials andTypes of soil reinforcement
There are 3 main materials which are commonly used in the
construction of reinforced soil:
• Soil or fill matrix
• Reinforcement or anchor system
• Geo-synthetics
1.Soil or fill matrix
• The shear properties of soil can be enhanced as theoretically any
soils from earth can be used. Usually the soil used is well graded
cohesionless or good cohesive frictional soils, however in many
instances pure cohesive soils have been successfully used.

6. • There are a few advantages
from using cohesionless soil:
- They are stable
- Free draining
- Not susceptible to frost
- Relatively noncorrosive
to reinforcing elements
• However, the main
disadvantage is the cost, as a
convenient compromise
between the benefits from
cohesionless soils and
economic advantages from
cohesive soils makes cohesive
frictional soils to be preferred.

7. 2.Reinforcement or anchor system
• A wide range of materials such as steel, glass, concrete,
fibre, wood, aluminium, rubber and thermoplastics can
be utilised as reinforcing agents. These reinforcements
can have the structural forms of strips, anchors, planks,
material chain, rope or a combination of these.
1) Strips:
• They can be comprised of copper, polymers, aluminium,
glass fibre or bamboo. Galvanised or coated steel strips
are paired with either plain or with projects to increase
the friction between reinforcement and fill.
These are flexible linear elements,
having their thickness less than their
breadth.

8. 2)Sheet:
This reinforcement may be formed from fabric or
metals such as galvanised steel sheet and
expanded metals.
3)Grids:
Grids are also used as reinforcements. They
consist of steel (in the form of plain or galvanised
weld mesh/ expanded metal).

9. 3.Geosynthetics
• Geosynthetics refers to man made product’s, they are flexible in nature
and planar (sheet like).
• These materials are manufactured from synthetic polymers and
sometimes of natural materials.
• These are vital in the engineering field as they are used as filters,
drains, reinforcements, barriers and have erosion control applications.
• Geotextiles are a permeable synthetic textile material; this is generally
produced from polyester or polypropylene polymers.
• These are used to increase the overall soil strength, stability, prevent
erosion and aid in drainage.
• A range of geotextiles can be produced using various manufacturing
processes and different polymers, they can be woven or non-woven.
1)Woven geotextiles are made by interlacing 2 or more fibres (at
right angles).
2)Non-woven are produced by mechanical bonding or needle punching.

10. Thank you