J. C. E. T. YAVATMALJ. C. E. T. YAVATMAL

Present By Present By Mr. Amit H. ShidurkarMr. Amit H. Shidurkar

2nd Year Civil Engg.2nd Year Civil Engg.

Department of Civil Department of Civil Engg. Engg.

A Seminar OnA Seminar On

IndexIndex• INTRODUCTIONINTRODUCTION• METHODS FOR GROUND IMPROVEMENTMETHODS FOR GROUND IMPROVEMENT• SOIL STABILIZATIONSOIL STABILIZATION• VERTICAL DRAINSVERTICAL DRAINS• SOIL NAILINGSOIL NAILING• STONE COLUMNSSTONE COLUMNS• VIBRO COMPACTIONVIBRO COMPACTION• Conclusion Conclusion • References References

INTRODUCTION Transportation - needed for the

development of the country. The main mode of transportation is

by road or highways. In the process of road

development, the alignment of road may have to be fixed through the soils which may not bear the traffic loads .

There are various techniques of ground improvement.

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METHODS FOR GROUND IMPROVEMENT

1. Soil stabilization2. Vertical drains3. Soil nailing4. Stone columns5. Vibro compaction

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SOIL STABILIZATION Improvement of stability or bearing capacity

of soil by use of controlled compaction or by the addition of suitable admixtures or stabilizers .

There are various methods of soil stabilization .

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The methods of soil stabilization are:

1. Mechanical Stabilization 2. Soil-cement Stabilization 3. Soil-lime Stabilization 4. Soil-bitumen Stabilization 5. Chemical Stabilization 6. Electrical Stabilization 7. Stabilization by grouting 8. Stabilization by geotextile and fabrics9. Reinforced earth10.Using bioenzymes

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VERTICAL DRAINS Act as free draining water channel.

surrounded by a thin filter jacket which prevents the surrounding soil from entering the core.

A vertical sand drain accelerates the rate of consolidation.

Installation of vertical sand drains is a convenient technique for stabilization of soft and compressible soil .

There are two types of vertical drains - sand drains and sand wicks.

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Fig : vertical drains

Sand drainsSand drains Typically 200-500 mm in dia. Formed by infilling sand in to a hole in the

ground. Hole formed by driving ,jetting or augering. Typical spacing 1.5 - 6.0 .

Sand wicksSand wicks Sand wicks are improved technique of sand

drains. A small diameter hole is made by driving

mandrel or by boring. Then cylindrical bag with sand is lowered

into this. 9

SOIL NAILING Earth retention structure that combines

reinforcements and shortcrete to support excavations , hillside , embankment steeping etc…

The nails must have bending stress. The tension developed in nails provides resisting forces which stabilize the soil mass.

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Fig: Soil nail11

STONE COLUMNS Done to provide adequate support for

relatively light foundation. The method consists of forming vertical

holes in ground which are filled with compacted crushed stone, gravel and sand or a mixture.

Fig : stone columns

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VIBRO COMPACTION For loose sand deposits, the density index

can be increased by vibro compaction.

This process employs a depth vibrator suspended from crane

Compaction of sand can be achieved up to distance of 2.5m from axis of vibrator.

Compaction can be carried out to significant depths up to 12m.

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Fig : vibro-compaction 15

CONCLUSIONS

While constructing highways different ground conditions are encountered. Considering all factors a suitable ground improvement technique has to be done. Ground improvement techniques have been extensively used by developed countries.

Lime stabilization is suitable for expansive soil like black cotton soils.

In bitumen stabilization optimum content of bitumen vanes from 4 to 6 % soil.

Electrical and Chemical stabilization are expensive compared to others.

Stabilization by grouting is suitable only for soils with high permeability.

Stabilization by Terra Zyme is most effective for fine grained soil.

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REFERENCES Sanjay Kr Singh & Pradeep Kr Gupta, (2002), "Critical

review of ground improvement techniques for highways", Vol 30, No: 8, Indian Highways, NewDelhi, pp. 5-13.

Gaulkar.M.P, (1999), "Construction of roads III black cotton soils", Vol 27, No: 3, Indian Highways, New Delhi, pp. 37-43.

Sharma.S.C, (1994), "Ground Improvement Techniques", Vol. 22, No: 12, Indian Highways, New Delhi, pp. 3-4.

(1994), "Application of Geogrids in Highway Engineering", Special report: 12, Indian Road Congress, New Delhi, pp. 59-61.

Biju.P.B, Kuncheria.P.Issac, (2003), "Studies Stabilization Using TerraZyme for Pavement (M.Tech Thesis Report). on Soil Subgrade"

Sharma.V.M. et.al, (2000), "Soil Nailing" ,Vol:28, No: 1, Indian Highways, New Delhi, pp. 46-52.

Arora.K.R, (2003), "Soil Mechanics and Foundation Engineering", Standard Publishers

Distributors, Delhi. 17

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