Jute geo textile as a slope stabiliser

Jute Geo Textile As a Slope Stabilizer

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Geotextiles- more aptly Geosynthetics –belong to the class of Technical Textiles under GEOTECH category.

Geotextiles are generically of two

varieties—one variety is made of synthetic polymers (petrochemical derivatives) and the other of natural fibres (such as jute, coir)

Geotextiles are intended to improve engineering performance of soil on or in which it is laid

What Are Geotextiles?

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Jute Geotextiles

Jute Geotextiles (JGT)-as the name suggests –is made of bast fibres of jute plants—a renewable agri-resource under cultivation in the Ganga-Brahmaputra delta for centuries. Presently under cultivation in other areas/countries as well

The British were the first to discover the potential of jute fibre for flexible packaging (sacks) after elaborate tests

The features of jute fibre conform to technical requirements of geotextiles, besides its added advantage of being eco-concordant, abundant availability, and industry-expertise to make customized JGT

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High moisture absorbing capacity

Excellent drapability (the best of all GTs)

High modulus of elasticity

Low extension-at-break

High roughness co-efficient

Excellent spinnability

Bio-degradability with mulching & soil-nourishing properties

Annually renewable resource with abundant availability

Economical &

Eco-friendly

Advantages of JGT

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JGT matches its man-made counterpart in the three basic functions of a geo textile. They are Separation, Filtration, Drainage. Besides,

Along-plane drainage capability (i.e. transmissivity ) of JGT is higher than its man-

made counterpart.

Fineness of jute fiber enables manufacture of JGT according to the specified

porometric features

High Roughness Co-efficient of jute ensures better load transference & confining

action on soil

JGT has far greater water absorbency than all other GTs –a quality which enables

sustained release of the absorbed water, thus creating a congenial micro-climate

for better growth of vegetation

JGT – Basic Functions

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Civil engineering Applications of JGT

Strengthening of road by improving CBR

Slope management

Protection of river bank against erosion

Stabilizing embankments

Prevention of railway track settlement

Consolidation of soft soil

Control of surface soil detachment

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Slope Management with JGT

Roads built on high embankments and slopes at construction sites require

preventive measures to control erosion of slope surface.

Slopes erode due to: Detachment of top soil by K E of rain drops Flow of rain water (surface run-off) Severe wind

Surface soil erosion can be controlled by reducing the velocity of surface run-off

& entrapping detached soil particles.

Wind-induced soil erosion can be controlled by suitable JGT- cover

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Slope Management with JGT

Remedial Concept

• Universal Hydrological Equation in its simplest form states precipitation surface flow + through flow ( sub-surface flow ) + storage.

• If through-flow and on-land storage can be increased, surface run- off gets reduced.

• Through-flow depends on hydraulic conductivity of the soil. Storage can be facilitated by creating micro-barriers on the slope. Such micro-barriers also decrease the velocity of surface flow.

• JGT is the ideal material that fulfills the requirements, besides facilitating fast growth of vegetation on its bio-degradation as a result of its mulching properties and by increasing the hydraulic conductivity of soil.

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Soil Erosion Process on a Slope

RAIN

- - - -- - - - -

XC

belt of no erosion

FLOWactive erosion

deposition of sediments

D

ad

bb’e

c’ c

material in suspension

overland flow

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Installation of JGT on slope

Direction of laying

Jute Geotextile

Fixing nail

Graded slope

Grass plant

Toe anchor(150 mm x 150mm)

150

Shoulder anchor(150 mm x 150mm)

150 mm

50 mm

Fixing nail(II Gauge wire)

+

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Role of JGT in Filter-cake formation in soil

FILTER CAKE FORMATION IN SOIL

IS AN OPTIMAL STATE OF SOIL CONSOLIDATION

TRIGGERING GRADUAL DEVELOPMENT OF EFFECTIVE STRESS WITHIN A SOIL MASS, THUS ENABLING IT TO BEAR GREATER LOAD.

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Effect of vegetation

The surface vegetation prevents the direct impact of water droplets to the surface of soil.

Leafs of the large trees stores rain water for some time and after wetting a large surface area, a reduced amount of water is getting to the soil surface.

Stems and shoots roughen and loosen the ground to enable water to

infiltrate more easily.

Finally it reinforces the slope by binding the loose soil with it’s root network

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Durability of JGT

Loss of strength of JGT after a year is NOT a drawback – for, by that time, JGT provides a self-sustaining sub-grade for most soils.

The gain in strength of the sub-grade compensates the loss of strength of JGT within the same time frame

With the passage of time dependence on JGT for soil stability continues to decrease

However there is need to ensure JGT-durability ranging from 2 to 4 years (depending on the application-type) by special treatment. Eco-friendly durability treatments have been developed by IIT, KgP & IJIRA

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Bio-degradability of JGT: a Technical Disadvantage?

The answer is NO. Optimal consolidation (development of effective stress) is seen to take place within the effective life of JGT

N.B. Effective life of JGT may be enhanced by specially developed eco-friendly water-repellent treatment

(developed by IIT Kgp & IJIRA

Necessity of JGT or, for that matter, of any GT ceases after filter-cake formation.

Bio-degradability of JGT is thus not a technical disadvantage. Additionally JGT lends environmental advantage to the construction

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Some Photographs showing application of JGT for Stabilization of Slope

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NH-3, GUNA BYPASS, M.P.

LAYING OF JUTE GEOTEXTILE ON AN EMBAKMENT

Fig 1

Fig 2

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SLOPE COVERED WITH VEGETATION

LAYING OF JUTE GEOTEXTILE AFTER DRESSING OF SLOPE

HILL SLOPE GUWAHATI-SHILLONG ROAD AT SONAPUR

Fig 3

Fig 4

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Fig 7. Leveling of the damaged road with earth

Fig 5. Condition of Damaged Road

Fig 8.Finished road after 7 years of construction

Fig 6. Laying of JGT over sand

Kakinada Port Area, Andhra Pradesh

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BRIDGE APPROACH ON R.MUNDESHWARI, West Bengal

SLOPE COVERED WITH VEGETATIONON THE SLOPE NEAR A BRIDGE

Fig 9

Fig 10

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Conclusion

• JGT is an effective technical facilitator in building stronger and stable slopes with the added advantage of lending eco-concordance by reducing carbon footprint & ensuring overall economy.

• Jute plays a significant role in national economy as a major

FE earner & one of the largest employers of work-force in India

JGT JUSTIFIABLY DESERVES MORE ATTENTION & SUPPORT…… 20

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