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Modern  GROUND IMPROVEMENT TECHNIQUES FOR HIGHWAYS Modern  GROUND IMPROVEMENT TECHNIQUES FOR HIGHWAYS

Modern GROUND IMPROVEMENT TECHNIQUES FOR HIGHWAYS - PowerPoint Presentation

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Modern GROUND IMPROVEMENT TECHNIQUES FOR HIGHWAYS - PPT Presentation

PRESENTED BY ARCHANA MALLICK 7 TH SEMCIVIL INTRODUCTION T ransportation contributes to the economicindustrialsocial and cultural development of any country Transportation by road or highways is the only mode which could give maximum service to one and all ID: 562315

soil ground vibro improvement ground soil improvement vibro drains compaction process vertical nailing water piers soils vibrator column typically

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Slide1

Modern GROUND IMPROVEMENT TECHNIQUES FOR HIGHWAYS

PRESENTED BY

ARCHANA MALLICK

7

TH

SEM,CIVILSlide2

INTRODUCTION

T

ransportation contributes to the economic,industrial,social and cultural development of any country.

Transportation

by road or highways is the only mode which could give maximum service to one and all.

When the soil on a project site cannot support the loads, ground improvement to increase strength, reduce compressibility, and enhance performance under applied loadings may be required.

The field of ground improvement techniques has been recognized as an important and rapidly expanding one.

Various methods are discussed below:Slide3

METHODS FOR GROUND IMPROVEMENT

1. VERTICAL DRAINS

2

. SOIL NAILING

3

. STONE COLUMNS

4

. VIBRO COMPACTION

5

. DYNAMIC COMPACTION

6

. VIBRO PIERSSlide4

VERTICAL DRAINS

These consist of a column of pervious material placed in cylindrical vertical holes at sufficiently close spaces.

All drains should be connected at the ground surface to a drainage blanket.

Vertical drains accelerate consolidation by facilitating drainage of pore water.

Vertical drains are laid out in rows, staggered, or aligned to form patterns of equilateral triangles or squares.

Two types of drains are discussed belowSlide5

SAND DRAINS

A sand drain is a simple process, employing a column of at least 10 inches in width

augered

into ground to be surcharged and consolidated.

The column is then filled with sand and connected to a free-draining blanket of granular soil. Slide6

WICK DRAINS

A wick drain is usually about, 4 inches wide, 1/8-inch thick which acts as a high-permeability conduit for water to flow out of the soil and to the surface.

M

ost common application of wick drains is for accelerating the settlement rate of compressible soils.Slide7

SOIL NAILING

This ground reinforcement process uses steel tendons which are drilled and grouted into the soil to create a composite mass.

A

shotcrete

facing is typically applied

.

Soil Nailing is an in situ technique for reinforcing, stabilizing and retaining excavations and deep cuts.

Soil nailing is not practical in:

Soft, plastic clays

Organics/Peat

Fills (rubble, cinder, ash, etc.)

Slide8

APPLYING SHOTCRETE

HOLES DRILLED THROUGH MACHINESSlide9

SOIL NAILINGSlide10

STONE COLUMNS

A

lso known as

vibro

-replacement or

vibro

-displacement, is a ground improvement process where vertical columns of compacted aggregate are formed through the soils to be improved.

The vibrator first penetrates to the required depth by vibration and air or water jetting or by vibration alone.

Gravel is then added at the tip of the vibrator and progressive raising and

repenetration of the vibrator results in the gravel being pushed into the surrounding soil.

The soil-column matrix results in an overall mass having a high shear strength and a low compressibility.Slide11

STONE COLUMNSSlide12
Slide13

VIBRO COMPACTION

It is a ground improvement process for

densifying

loose sands to create stable foundation soils.

The action of the vibrator, usually accompanied by water jetting, reduces the inter-granular forces between the soil particles, allowing them to move into a denser configuration, typically achieving a relative density of 70 to 85 percent.

Compaction is achieved above and below the water table.Slide14

PROCESS OF VIBRO COMPACTIONSlide15

DYNAMIC COMPACTION

Dynamic Compaction is the dropping of heavy weights on the ground surface to

densify

soils at depth.

It involves the repeated dropping of large steel tampers by means of crawler cranes.

Tampers typically range from 6 to 20 tons and are dropped from heights of about 40 to 80 feet. Slide16

MACHINE WITH TAMPER

COMPACTION BY TAMPERSlide17

VIBRO PIERS

Vibro

Piers, also known as aggregate piers, are typically installed to intermediate depths of 5 to 20 feet for the support of new loads.

Vibro

Piers are quick to install and very effective at reinforcing the surrounding soil.

Typical

Vibro

Pier construction begins with pre-drilling a full-depth hole with a diameter that is equal to the final pier design diameter.

For soils in which the pre-drilled hole will not stay open, the bottom feed process can be used to avoid the need

for casing.Slide18

BOTTOM FEED PROCESS

AGGREGATE INTRODUCED THROUGH PREDRILLED HOLESSlide19

CONCLUSION

Though the term Ground Improvement has been familiar to Civil Engineers, the design approach is still empirical, mostly based on past experience.

The

Importance of Ground Improvement is

immeasurable

. Ground stability is a vital part of any construction

project.

Method adopted to be applied on the field should be according to site condition and economical.

Application of Ground Improvement Techniques is not only cheaper but also reduce the construction time significantly.

Ground improvement technique also plays a vital role in the development of our mother land by 2020.Slide20

REFERENCES

K.R.Arora

, (2005)"

Soil Mechanics and

Foundation

Engineering", Standard Publishers Distributors, Delhi.

www.haywardbaker.com

.

TerraSystems

(Geotechnical Contracting Firm) .www.google.com Rembco Geotechnical Contractors Inc.Slide21

THANK YOU