Role of Textiles in Soil Erosion Control

Submitted to :

Prof. AlagiruSamy

Submitted by:Ashutosh Shukla

Erosion is a natural process in which soil and rock material is loosened and removed by the action of water, wind, and ice

The problem of soil movement due to erosive forces by moving water and/or wind as well as by seeping water is called soil erosion.

Soil erosion and sediment controls are measures which are used to reduce the amount of soil particles that are carried off of a land area and deposited in receiving water.

Soil Erosion

Geological erosion• Includes soil-forming as well as soil-removing, has

contributed to the formation of soils and their distribution on the surface of the earth.

Man-made erosion• Includes the breakdown of soil aggregates and the

increased removal of organic and mineral particles; it is caused by clearing, grading, or otherwise altering the land. Erosion of soils that occurs at construction sites

Classification

Introduction to the types of erosion

Sheet erosion Occurs when thin layers of the top soil are moved by the force of the runoff water, leaving the surface uniformly erodedRill erosion Caused by runoff water when it creates small, linear depressions in the soil surfaceGully erosion Large, wide channels carved by running water

Coarse fragments:- are easily identified- not many erosion issues

Fine earth portion:- harder to identify- has higher erosion potential

Know your soils

Soil Reinforcement & Errosion control using Geosynthetics

Geosynthetics :

The membranes used in contact with or within soil are termed as geosynthetics.

They are used in subgrade stabilization, soil reinforcement, surface erosion control, subsurface drainage etc. Generally Polymer based - Polypropylene, Polyester, PVC, Polyamide, Polyethylene

The ASTM (1994) defines geotextiles as permeable textile materials used in contact with soil, rock, earth or any other geotechnical related material as an integral part of civil engineering project, structure, or system.

Geotextile

• Soil Reinforcement by Geotextiles

The structural stability of the soil is greatly improved by the tensile strength of the geosynthetic material. This concept is similar to that of reinforcing concrete with steel.

Reinforcement function of geotextiles

Soil is a structure with high compression strength but with low tensile strength. Geotextiles being high tensile strength materials are ideal to increase soil quality and soil structural stability Geotextile increase load bearing capacity of soil through tensile mechanism.

Erosion Control Mechanism and Role of Geotextiles

Erosion is caused by a group of physical and chemical processes by which the soil or rock material is loosened, detached, and transported

the geo-textile protects soil surfaces from the tractive forces of moving water or wind and rainfall erosion

Geotextiles are also used for temporary protection against erosion on newly seeded slopes. After the slope has been seeded, the geotextile is anchored to the slope holding the soil and seed in-place until the seeds germinate and vegetative cover is established

Vegetation can form the best erosion control, but this is often difficult to establish. The use of hydroseeding or seed impregnated fabric can be an effective method to

establish vegetation.

Condition of river bank with and without geotextiles

Application of erosion control mat(Vishakhapatnam, A.P.)

Different Textile Structures Used For Soil Reinforcement

Methods to use textile structures for soil reinforcement Geosynthetics Geotextile wrap-around revetments (GWRs) Fibre reinforced sands

Geosynthetic Structures used for soil reinforcement

Biaxially

oriented process

nets (BOP)

Erosion control meshes

Erosion control

blankets (ECBs)

Geogrids

Biaxially oriented process netsManufactured from polypropylene or

polyethylene resinsExtremely versatile in that

composition, strength, elongation, aperture size and shape, colour and ultraviolet stability

Can easily be designed into the product for specific site requirements

BOP nets have proven to be so adaptable they are being used to create more complex product

Installation of these products is less labor intensive

Biaxially oriented process

nets (BOP)

Erosion control meshes

Erosion control

blankets (ECBs)

Geogrids

Erosion control meshes

A step up from BOP nettings are woven polypropylene geotextile erosion control meshes.

Twisted fibre erosion control meshes.Theses high strength polypropylene meshes

protect the soil surface from water and wind erosion while accelerating vegetative development.

Used for fostering vegetation on geosynthetically reinforced steepened slopes

Biaxially oriented process

nets (BOP)

Erosion control meshes

Erosion control

blankets (ECBs)

Geogrids

l-2-m wide biodegradableComposed of straw, excelsior, cotton,

coconut, polypropylene or blends thereof.Contain UV stabilizers for controlled

degradationApplications for the wide variety of

blankets range from protection of gradual to steep slopes to low or moderately flowing channels

Erosion control blankets (ECBs)

Biaxially oriented process

nets (BOP)

Erosion control meshes

Erosion control

blankets (ECBs)

Geogrids

GeogridsThese are plastic materials formed into a very open grid like

configuration with very large apertures.bridge abutments to be constructed where the sill beam rests directly on

the Geosynthetic Reinforced Soil (GRS) block.Grid made up of PVA works in textile grid applications to withstand

high alkali environments and especially the combination of lime and cement stabilizers

PVA grids in cohesive soils where there appears to be a synergistic effect resulting in higher strength and higher resistance to pull out failure

Use of Synthetic Geogrids for Erosion

Control of Natural Existing Slopes

Reinforced embankment of unstable foundation soil

: Geogrids to avoid reflective cracking in pavements

TERMs versus PERMs At this point an important distinction must be presented regarding the intended use of E &

SC materials. For many installations vegetation alone will provide adequate long term erosion

protection. Getting vegetation established requires a variety of techniques. Materials of a temporary

nature which facilitate vegetative establishment, then degrade, may be termed TERMs (temporary erosion and re-vegetation materials).

Basically TERMs consist of degradable natural and/or synthetic components which provide temporary erosion control and facilitate vegetative establishment. These short term materials degrade leaving only vegetation for long term low to medium flow resistance.

Site conditions requiring reinforced vegetation or revetment systems will require PERMs (permanent erosion and re-vegetation materials).

Geotextile wrap-around revetments (GWRs) GWRs are sand slopes that are reinforced with a geosynthetic the material is wrapped and encapsulated with geotextiles to create a flexible revetment A layer of geotextile is first placed at the site and sand is placed on top of it to produce a GWR Loose ends of the geotextile are then folded back and inserted into the fill. A second geotextile layer is laid on top and the procedure is repeated until the layers reach to the designed height The structure resists overturning because of its weight Even it resists seaward sliding because of the geosynthetic’s tensile strength.

Advantages

They are useful for protection against waves and currents,

Other structures can be constructed directly upon them,

Total construction and life cycle costs are generally lower than those of hard structures

Recent developments obtained from small-scale model testsThe only recorded model tests involving GWR were conducted at the large wave flume at Hannover, Germany (Saathoff and Kohlhase, 1986). Model tests were performed on a three-layer geotextile structure; they were tested with waves up to 1.3m (Fig. left). The GWR structure suffered only slight deformation. Based on those model test results, a GWR was constructed at the island of Sylt in Germany

Cross section of model tests at the large wave flume in Hannover and prototype constructed in Sylt, Germany. Previous model test and prototype of wrap-around revetments

Fibre reinforced sands

Reinforcing soils using tension resisting elements is an attractive means of improving the performance of soil in a cost effective manner.

The use of random discrete flexible fibres mimics the behaviour of plant roots and gives the possibility of improving the strength and the stability of near surface soil layers

The discrete fibres are simply added and mixed randomly with soil, much like cement, lime, or other additives

Fibres some times used in combination with other admixtures such as cement and fly-ash to increase the shear strength of the soilClassificationMcGown classified soil reinforcement into two major categories1. Ideally inextensible- includes high modulus metal strips that strengthens soil

and inhibits both internal and boundary deformations. Catastrophic failure and collapse of soil can occur

2. Ideally extensible inclusions- include relatively low modulus natural and/or synthetic fibres, plant roots; and geosynthetics. provide some strengthening but more importantly they present greater extensibility

Fibres used for soil renforcement

I. Natural fibres

Coconut (coir) fibre Sisal Palm fibres JUTE Flax Bamboo Cane

II. Synthetic (man-made) Fibre

Polypropylene (PP) fibres Polyethylene (PE) fibres Glass fibres Steel fibres Polyvinyl alcohol (PVA) fibres

Applications of fibre reinforced soil

Using natural and/or synthetic fibres in geotechnical engineering is feasible in different fieldspavement layers (road construction),retaining walls,railway, embankments,protection of slopes,Soil-foundation engineering.Geogrid Applications For Reinforced Soil Slope

ProtectionProvision of Geotextiles Against Subgrade and

Embankment ErosionGeosynthetics for Highway Pavements

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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 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

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

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JGT – Basic Functions

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 30

Advantages of JGT

Conclusion

•Geotextiles, specially 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.

References

Sayyed Mahdi Hejazi, Mohammad Sheikhzadeh, Sayyed Mahdi Abtahi, Ali Zadhoush. A simple review of soil reinforcement by using natural and synthetic fibers. Construction and Building Materials 30 (2012) 100–116.

Chao-Sheng Tang*, Bin Shi, Li-Zheng Zhao. Interfacial shear strength of fiber reinforced soil. Geotextiles and Geomembranes 28 (2010) 54–62.

Fauziah Ahmad*, Farshid Bateni, Mastura Azmi. Performance evaluation of silty sand reinforced with fibres. Geotextiles and Geomembranes 28 (2010) 93–99.

Nilo Cesar Consoli a, Ma´ rcio Antoˆnio Vendruscolo, Anderson Fonini, Francisco Dalla Rosa. Fiber reinforcement effects on sand considering a wide cementation range. Geotextiles and Geomembranes 27 (2009) 196–203

Radoslaw L. Michalowski, Jan C˘ erma´. Strength anisotropy of fiber-reinforced sand. Computers and Geotechnics 29 (2002) 279–299

Ashis Mitra, Visva-Bharati University. Geotextiles and its Application in Coastal Protection and Off-shore Engineering.

Ennio M. Palmeira, Fumio Tatsuoka, Richard J. Bathurst, Peter E. Stevenson, Jorge G. Zornberg. Advances in Geosynthetics Materials and Applications for Soil Reinforcement and Environmental Protection Works. EJGE.

Kazuya Yasuharaa, Juan Recio-Molinab. Geosynthetic-wrap around revetments for shore protection. Geotextiles and Geomembranes 25 (2007) 221–232.

Chaosheng Tang, Bin Shi_, Wei Gao, Fengjun Chen, Yi Cai. Strength and mechanical behavior of short polypropylene fiber reinforced and cement stabilized clayey soil. Geotextiles and Geomembranes 25 (2007) 194–202.

Dr. Bipin J Agrawal. Geotextile: it’s application to civil engineeering – overview. National Conference on Recent Trends in Engineering & Technology.

References …..Contd…..

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