CE5350 Introduction.pdf

7/21/2019 CE5350 Introduction.pdf

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CE5350Geos nthetics

&

Reinforced

Soil

Structures

NPTELVideo:GeosyntheticsandReinforcedSoilStructures

http://www.nptel.iitm.ac.in/courses/105106052/


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withsoil

in

geotechnical

constructions.

Natural:coir,

jute,

hemp,

etc.

Artificial: ol mericormetallic


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TYPES OF GEOSYNTHETICS Geotextiles

Geogrids Geonets

Geomembranes

Pre-fabricated vertical drains PVD

Geosynthetic Clay Liner (GCL)

- Geocomposites & Geo-others


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Graphical symbols proposed by IGS

letter


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Letter Symbols for

Different Functions of Geosynthetics

B Barrier (fluid)D Drainage

E Surficial Erosion Control

F FiltrationP Protection (of geomembranes)

R Reinforcement

S Separation


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FlexibleBreakwaterunitmadeof

geosyn e cs

eac

san

e

ags

inropenetgabions


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REINFORCED SOIL

Soil+reinforcement=reinforcedsoil

Reinforcement:Ancient:Treebranches,grassreeds,straw,rootsof

v g , , u

Modern: Steel,polymeric,naturalmaterials

tension

Combinedproducthasmuchbetterengineeringproperties

v u

u Reinforcedsoilconceptissimilartothatofreinforced

concrete


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Need for Retaining Walls

o as g compress ve strengt ut m te

tensile and shear strengths

repose Stee er slo es re uire lateral su ort

Purpose of the retaining walls is to provide lateral

support to the soil to make it stand at steep anglesInitialsoilposition

withsteepslope

Finalslope

at

angleofrepose

cv


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Unreinforced

Embankments

slope

9


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Reinforced Soil

m an men s

slope

Stee

reinforced

spacegained

slope

10


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Conventional

Retainin

Walls

MasonrygravityretainingwallReinforcedconcretesemigravityretaining

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Componentsofreinforcedsoilretainingwalls

layers

ac soac ng

panelsLevelling pad

-

Levelling pad is usually 150 mm thick and 300-400 mm wide

Backfill soil is select non-plastic fgranular fill

12


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Constructionofairportat

13

,

Ms/

Maccaferri India


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14Constructionof

33

m

high

embankment

at

Shillong

bypass

Road


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Brief history of MSE Walls in India

First

MSE

wall

in

mid

1980s

at

Ludhiana MostRoBs onNHAIprojectsbuiltusingthistechniques

VerycommontoseeMSEwallheightsmorethan10m

Geosyntheticsand

steel

ladders,

steel

strips,

plymeric

s r ps,anc orsys emsuse as ma er a s

Soilandflyashusedasbackfillmaterial

OneprojectcurrentlyunderwayinSikkimwithheight

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DifferentTypesofREWallsbuiltinIndia

Fullheightwalls Modularblockwalls Panelwalls

Steelmeshreinforcement Steelstripswithanchor Gabionfacings

Geogridreinforcement Polymericstripreinforcement16


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View of 2-tier Wall from Krishna River17


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Topviewofthecompleted4tierwall18


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Viewof

the

additional

parking

space

gainedatthetopofthehill

19


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Bituminous wearing course

Base course

TSub-base course

Subgrade soil

Thickness of the pavement (T) depends on the

s reng o su gra e so , ra c oa ng, es gn e,

properties of layers


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WBM material

WBM

GSB

WBM & GSB Layers in a flexible pavement


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T ical Granular sub-base GSB la er in a flexible avement


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aggregatelayergeotextileseparator

subgrade

soil

Prevents the intermixing,

prevents piping, strength of

aggregate is preserved


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Drainagefunctionofageotextilelayer

ingressofwaterintopavementlayers

flowofwaterflowofwater

ra n

Thick geotextile with good drainage properties is

used at interface


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FiltrationFunction

Geotextilelayeractingas

a

filter

Watercomingoutleavingbehind

the

fine

soil

particles

intact


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Conceptual representation of filtration phenomenon

Larger particles have

arger n er-par c e

space

Filter layer(s)

Flow

direction

Base soil

Pore pressure dissipation through soil


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Simpleexplanationofthefilter

Tea filter should allow the

passage of liquid tea whileretaining the tea powder

If the openings in the filter are

large, tea powder will flowroug , w c s un es ra e

If the filter openings are too,

through freely, which is also notdesirable


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Geogrid reinforced pavement construction

wrinkles in the geosynthetic


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BackDumpingAggregate

Minimum cover of 150 to 200 mm soil above geosynthetic


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Geocell reinforcedflexiblepavement


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Compact the Aggregate

using suitable compaction equipment.


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Cover system

GL GL

as e e -up n ayers

with alternate soil layers

Liner system


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Barrier concept in landfills (Gartung 1996)


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typesofgeosynthetics

yp ca crosssec ono a an w eren ypeso geosyn e cs


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Hindustan Zinc Factory, Visakhapatnam


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Embankment was constructed using the granules

o zeros e m xe w murum so


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reinforcement used to maintain steep slopes


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Linin of the surface with HDPE eomembrane


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Spreading the geomembrane layer down the slope (notice

the joints along the slope and not across the slope)


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Rolls of geomembranes ready to be rolled on the landfill slopes


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Leak testin of eomembrane seams


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ATNSCB

House

lost

into

sea

due

to

coastal

erosion

in

May

2012


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Dee ulle s formedonhi hwa slo esb rainwater

inducederosion noticethefinesilty soilwhichishighly

susceptibleto

erosion


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ew o e an a er cover ng w vege a on


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Use of coir mat to

promote vegetation

growth to preventsurface erosion

54/48Geosynthetics - Introduction


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UseofstonefilledropenetgabionsforshorelinestabilizationatSwami

ara n emp e, a , u ara

55/48Geosynthetics - Introduction


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ComponentsoftheGrassPlant(Hall1992)


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InnovativeuseofgeogridsforshoreprotectionatNavi Mumbai


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S . No. Topic Approx. no. o c asses1 Introduction to course and different types

of geosynthetics & applications

3

2 Principles, concepts and reinforcement 4

Mechanism

3 Types of polymers and manufacture of

geosynthetics

2

4 Determination of ro erties of 7

geosynthetics

5 Design of road bases and earth beds using

geosynthetics

5

7 Design of reinforced soil embankments 6

8 Soft ground improvement using PVDs &

other geosynthetics

3

pp ca ons o geosyn e cs n an s

10 Case studies & summary of course 2Total 41

CE5350 Introduction.pdf

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