Types And Functions Of Geosynthetics.pdf 2r5b5h

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Dr.G.Venkatappa Rao

Geosynthetics • Construction Material – compare with cement & steel • Is a Technology - Engineering with Geosynthetics • Process of development • Technology groups involved – Polymer, Textile Civil 27 July 2016

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Historical - Roads • Use of coconut leaf mattresses in Kerala in road construction • Dragging a bogged down vehicle using leaves, brushes etc • Cordruoy roads using tree trunks packed next to one another and levelling with gravel for traffic in forest areas • Natural erosion control by vegetation – turfing, trees etc 27 July 2016

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Geosynthetics • Modern civil engineering construction materials • Modify/Improve soil/geologic material behaviour • Developed/Synthesized for specific function or application in construction • More than 1billion sq m annual use

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GEOSYNTHETICS • They generally replace scarce raw material resources like steel/cement/aggregates • They are good alternatives to conventional designs • They are, sometimes, the only means of construction • They can be rapidly installed • They can revitalise textile industries ??? 27 July 2016

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What Are Geosynthetics? A planar, polymeric (synthetic or natural) material used in with soil/rock and/or any other geotechnical material, for Filtration, Drainage, Separation, Reinforcement, Protection, Sealing and Packing.

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Geosynthetics –The wide variety • Geotextiles –Woven, non-woven Filter fabrics • Geogrids • Geomembranes • Geocomposites • Geonets, Geofibres,mesh mattings, Geopipes

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What Are Geotextiles and Related Products ? Geotextile A planar, permeable, polymeric (synthetic or natural) textile material, which may be nonwoven, knitted or woven, used in with soil/rock and/or any other geotechnical material in civil engineering applications.

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Continuous filament extrusion (after American Hoechst Corp.) 27 July 2016

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Flat Loom 27 July 2016

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Woven or Knitted Geotextiles

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Scanning electron micrographs of (2X1) twill weave monofilament fabric Geosynthetics - Introduction

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Woven geotextile

Scanning electron micrographs at interlacement point of woven fabric 27 July 2016

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A nonwoven geotextile in the form of a manufactured sheet, web or batt of directionally or randomly orientated fibres, filaments or other elements, mechanically and/or thermally and/or chemically bonded. Nonwovens are used in Filtration, Drainage, Separation, Protection and/or Erosion Control applications. 27 July 2016

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(Protection)

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The needle punching process (after American Hoechst Corp.) 27 July 2016

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Typical barbed needle (after American Hoechst Corp.) 27 July 2016

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Basic principles of needle punching process 27 July 2016

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Non-woven Geotextile

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Scanned electron micrographs of spun bonded fabric with different amplification

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B 27 July 2016

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C 27 July 2016

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Geogrids A planar, polymeric structure consisting of a regular open network of integrally connected tensile elements, which may be linked by extrusion, bonding or interlacing, whose openings are larger than the constituents, used in with soil/rock and/or any other geotechnical material in civil engineering applications.

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Geogrid Manufacture 27 July 2016

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Uniaxial Geogrid

Uniaxial Geogrid 27 July 2016

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Geogrid Biaxial 27 July 2016

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Extruded Geogrids

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Woven or Welded Geogrids

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Geonet • A planar, polymeric structure consisting of a regular DENSE network, whose constituent elements are linked by knots or extrusions and whose openings are much larger than the constituents, used in with soil rock and /or any other geotechnical material in civil engineering applications (IGS)

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Geonet 27 July 2016

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Geomembrane

• A planar relatively impermeable, polymeric (synthetic or natural) sheet used in with soil/rock and/or any other geotechnical material in civil engineering applications

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Geomembrane 





 

A planar, relatively impermeable, polymeric (synthetic) sheet with a minimum thickness of 1.0 mm. In landfill applications they are usually manufactured of HDPE with a thickness of > 1.0 mm, in > 2.5 mm. The surface can be smooth, profiled or textured and can be of importance for the shear behaviour. 27 July 2016

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Geocomposites

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Manufacture of GCLsCont’d

Adhesive mixed with clay 27 July 2016

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Geomat A three-dimensional, permeable, polymeric structure, made of bonded filaments, used to reinforce roots of grass and small plants and extend the erosion control limits of vegetation for permanent erosion control applications.

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Geosynthetics – composition • • • • • • 27 July 2016

Polypropylene HDPE Polyester PVC Synthetic Rubber Natural fibres – Jute, coir Geosynthetics - Introduction 66 G V RAO

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COIR GEOTEXTILES

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Rolls of RECBs

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Geosynthetics – the functions • • • • • • 27 July 2016

Separation Drainage Filteration Reinforcement Moisture barrier Cushion

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What is Separation? Definition • A Geosynthetic placed at the interface between two dissimilar geotechnical materials functions as a Separator when it prevents these materials from mixing under the action of applied loads

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Separation function

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Separation Applications Typical Application of Geosynthetics as Separators • At sub-grade/sub-base interfaces in temporary and permanent roads • Between railroad ballast and a foundation soil • Between embankment fill and soft foundation soil 27 July 2016

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Filtration and Separation Difference between two different soil types

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Filtration and Separation

.Nonwovens

are used in Filtration, Drainage, Separation, Protection and/or Erosion Control applications. 27 July 2016

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Drainage function

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Typical Applications (1)

BUILDING DRAINAGE

GARDEN ROOF

ROAD EDGE DRAINS

HORIZONTAL ROOFING

FINDRAINS

PARKING DECKS

RETAINING WALLS

PLANTERS

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REINFORCEMENT FUNCTION

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Geostrip • A polymeric material in the form of a strip, used in with soil/rock and/or any other geotechnical material in civil engineering

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Reinforcement function

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Function vs. Geosynthetic Type Type of Geosynthetic geotextile

Separation

Reinforcement

Filtration

Drainage

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geogrid

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geonet geomembrane

geofoam geocomposite

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geosynthetic clay liner geopipe

Containment

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First Reinforced Soil Wall in India – Ludhiana, Punjab - 1986

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BS 8006 1995

The Designed Section

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segmental facing units shear key or mechanical connector geosynthetic reinforcement layer

reinforced soil

geotextile wrapped drain retained soil granular levelling pad foundation soil

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Blockwork wall in S E Asia

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800

Gravity Walls

700 600

Crib / Bin Walls

500

MSE (Metals)

400

300

MSE (Geosynthetics)

200 100 0 0

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Height of wall (m) 27 July et 2016al. 1998 Koerner

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Placement patterns for reinforcement

(a) Even spaced-even length

(c) Even spaced-even length with short facing layers

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(One that Failed)!

(b) Uneven spaced-even length

(d) Even spaced-uneven length with short facing layers

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RAO 3rd European Conference on Geosynthetics

Geosynthetic materials 10.4m Stiff uniaxial geogrid 40 and 55 kN/m

Geocell mattrace : Uniaxial stiff geogrid 80 kN/m Biaxial geogrid 30 kN/m 27 July 2016

Vertical prefabricated drains: Width 100mm, Thickness 3 mm PP filter, Tensile strength 2.2kN Discharge capacity buckled 50.10--6 m3/s

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Placing Fill on Geotextile

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Soft soils in construction - low bearing capacity - excessive rutting - compressible layers - landslides - slope failure - uneven settlements -…

soil reinforcement needed ! 27 July 2016

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Stabilization of ballast layer Ballast Sub-base geogrid

sub soil

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Hydraulic Engineering Applications     

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Waterproofing of Dams Waterproofing of Canals Reservoir Liners/Floating Covers Tunnel Waterproofing & Rehabilitation Pipe Rehabilitation & Remediation Geosynthetics - Introduction RAO

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Waterproofing of Dams 

masonry, concrete, earth and RCC dams  GM is not a structural element, its waterproofing  many dams over 50-years old often have leakage; sometimes excessive leakage - Introduction GV  methods Geosynthetics are under rapid 27 July 2016 RAO development mainly in European Alps and in China

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(Lining a Concrete Dam)

(Concrete Dam Leaking!)

Geosynthetics - Introduction G Earth V (Lined Dam: Before Rip-Rap) (Completed Concrete Dam Lining)

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LINING SYSTEMS 

Canal and Pond Lining

(Lined Pond)

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Embankment over Soft clay Embankment Fill

Beware of ditches in this area!!!

Reinforcement: Full width or localised areas

Tr

Tr Soft Clay Foundation

Reinforcement tension develops as a vector of these forces

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Silt Fence - Installation

Maintenance of Silt Fences • Inspection - physical condition, depth of soil behind fence, base pullout, fabric condition • Clean-out when half-full. • Allow soil to overtop and install additional downhill fences 27 July 2016 Geosynthetics - Introduction G V RAO

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Geosynthetic in Waste Containment

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Function vs. Geosynthetic Type Type of Geosynthetic geotextile

Separation

Reinforcement

Filtration

Drainage

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geogrid

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geonet geomembrane

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geofoam geocomposite

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geosynthetic clay liner geopipe

Barrier

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Summary Geosynthetics are bona fide engineering materials - MORTH, IRC Test methods and designs are available – BIS, ASTM, BS Basic advantage is quality control of factory manufactured products Construction Quality by rigorous CQC/CQA Field performance has been excellent

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A presentation by

Sai Master Geoenvironmental Services Private Limited

Serving the Environment

SAI MASTER ACHARYA SRI EKKIRALA BHARADWAJA

THANK YOU

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Web Sites of Geosynthetic Organizations • Geosynthetic Institute (GSI)

• International Geosynthetics Society (IGS)

• Geosynthetics Materials Association (GMA)

• International Standards Organization (ISO)

• ASTM International

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