3. Introduction
Rapid development of infrastructures with scarcity of useful land forced engineers to
improve the properties of soil to bear the load transferred by the infrastructures.
The purpose of these techniques to increase bearing capacity and strength of soil reduce
the settlement to a considerable extent. Reduce the effects of contaminated soils.
The main goal of most soil improvement techniques used for reducing liquefaction
hazards is to avoid large increase in pore water pressure during earthquake shacking.
This can be achieved by densification of the soil and improvement of its drainage
capacity.
There are different methods like Physically, Mechanically and chemically modifications.
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5. Surface improvement
The surface improvement method enhances the bearing capacity of the ground and
prevents unequal settling by mixing, stirring and solidifying the soil from weak ground
and the cement-based solidification agent. This method cannot work from approx. 2 m
or more below the ground surface.
It does not necessitate a dedicated construction machine, this method can be applied to
construction sites of any size.
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7. Grouting
When the adhesives are injected under pressure through a pipe or boreholes into the voids of ground or in
between the structure, the process is termed as grouting.
Mixing adhesive and special material either in the soil surface or column of soil if required.
Natural soil
Waste
materials
Industrial by-
products
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9. Application of Grouting for different
outcomes:
Control of ground water during construction
Void filling to prevent excessive settlement
Strengthening adjacent foundation soils to protect them
against damage during excavation, Pile driving, etc.
Soil Strengthening to reduce lateral support requirements
Stabilization of loose sands against Liquefaction
Foundation Underpinning
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10. For gravely layers : cement base grout mixes are generally used.
For sandy gravel soil : Ultrafine grout mix can be used.
Mortar and pastes such as
cement to fill in holes or open
cracks.
Suspensions such as ultra-fine
cement to seal and strengthen
sand and joints.
Solutions such as water glass
(silicate).
Emulsions such as chemical
grout
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12. 12
The use of various grout mixes are very much
dependent on the nature of soil and gradation of
soil
N= (D15)soil / (D65)Grout
If N > 24, Grouting is considered feasible
If N < 11, Grouting is considered not feasible.
(Mitchell and Katti in 1981)
13. Jet Grouting
ultra high-pressure fluids or binders that are injected into the soils at high velocities.
These binders break up the soil structure completely and mix the soil particles in-situ to
create a homogeneous mass, which in turn solidifies.
This ground modification/ground improvement of the soil plays an important role in the
fields of foundation stability, particularly in the treatment of load bearing soils under
new and existing buildings; in the in-depth impermeabilization of water bearing soils;
in tunnel construction; and to mitigate the movement of impacted soils and
groundwater.
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15. Soil cement
Cement and other admixtures like fly ash ,blast furnace slag has been used in many
geotechnical and highway projects to stabilize the soil:
1. Shallow depth stabilization- sub-grade, sub-base and base course of highways and
embankment material.
2. Treatment of deep soils like soft soils and peaty soils.
benefits can be achieved by this process:
1. Increased strength and stiffness and better volume stability
2. Increased durability
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17. Heating
Due to heating, permanent change in soil properties are
observed and the material becomes hard and durable.
Settlements of clay under a given applied load increases with increase in temperature
The engineering properties of clay changes when it is heated to about 400°C. Heating
breaks the soil particle down to form crystal products.
Depends on the nature of soil temperature can be varied between 300°C to 1000°C.
However the safety of adjacent structures should be ensured while heating
1. Immobilization of radioactive or contaminated soil.
2. Densification and stabilization
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18. Freezing
This method is based on conversion of in-situ pore water by use of refrigeration.
Ice then acts as a cement or glue, bonding together adjacent particle or blocks of rocks
to increase their combined strength resulting in an impervious structure
Water expands about 10% by volume ,which does not itself impose any serious stresses
and strains on the soil unless the water is confined within a restricted volume.
1. Temporary underpinning
2. Temporary support for an excavation
3. Prevention of groundwater flow into excavated area
4. Temporary slope stabilization 18
19. Modification by Addition and Confinement
Techniques
The one of the method among ground improvement techniques is reinforcing the soil with
materials like steel, stainless steel, aluminum, fibers, fiber glass, nylon, polyster, polyamides
in the form of other strips or grids and Geotextiles
The Primary purpose of reinforcing a soil mass is to improve its stability, increasing its
bearing capacity and reduce Settlements and Lateral deformations.
Geotextiles and geomembranes, broadly speaking are synthetic fibres used to stabilize
structures built on soil.
Using reinforcement in the form of fibers, strips, meshes and fabric the soil can be modified
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21. Confinement Methods
The role of geosynthetic material varies in different application as it can serve as
reinforcement, separation, filtration, protection, containment, fluid transmission and
confinement of soil to improve bearing capacity.
Geocell reinforcement is a recently developed technique in the area of soil
reinforcement
It has a three dimensional, polymeric, honeycomb like structure of cells made out of
geo-grids inter connected at joints.
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22. Conclusion
Ground Improvement Techniques is a technically viable and cost effective solution for soils
which are weak in strength and treatment is to be done in order to make them suitable for
construction.
A suitable and cost effective technique for ground improvement can be designed, keeping in
view the following points:
1. Nature and type of soil
2. Intensity of loading and
3. Intended performance
Selection processes for ground improvement performs, improved analysis, and knowledge of
long term performance and understanding of effects of variability required to develop more
efficient designs.
Before selecting any ground improvement technique it is important to evaluate the cost of each
particular methods and their associated applications.
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23. References
Bruce, Donald A. An Introduction to the Deep Soil Mixing Methods as Used in Geotechnical
Applications. Publication no. FHWA-RD-99-138, U.S. Department of Transportation,
Federal Highway Administration; 2000, 135 pages
Deep soil mixing in the UK: geo-environmental research and recent applications
Land Contamination & Reclamation, 11 (1) (2003)
Welsh, J.P., & Burke, G.K. (2000), ―Advances in grouting technologyǁ, Proceedings of
GeoEng 2000. Melbourne.
Liu, J. (2003), ―Compensation grouting to reduce settlement of buildings during an adjacent
deep excavationǁ, Proc. 3rd Int.Conf. on Grouting and Ground Treatment, Geotechnical
Special Publication120, ASCE, New Orleans, Louisiana, 2: 837-844.
Varaksin, S.(1981), ―Recent development in soil improvement techniques and their
practical applicationsǁ, Solcompact Sols/Soils, Techniques Louis Menard, 15, rue des
Sablons, Paris, 38/39-1981.
https://www.youtube.com/watch?v=kvtn-27JJ1Y
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