Table Of ContentD
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Embankment construction projects on very soft soil often give rise to si Design and Performance
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displacement estimations, stability analyses, monitoring, and various
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other aspects involved. Extensive attention is furthermore paid to the t o
application of geosynthetics as a tool to improve the stability of soft soils S f E
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Márcio de Souza S. Almeida &
Maria Esther Soares Marques
Almeida Marques cover FINAL.indd 1 13-08-13 15:45
Design and Performance of Embankments
on Very Soft Soils
TThhiiss ppaaggee iinntteennttiioonnaallllyy lleefftt bbllaannkk
Design and Performance of
Embankments on Very Soft Soils
Márcio de Souza S. Almeida
Graduate School of Engineering,Federal University of Rio de
Janeiro,Rio de Janeiro,Brazil
Maria Esther Soares Marques
Department of Fortification and Construction Engineering,
Military Institute of Engineering,Rio de Janeiro,Brazil
‘DesignandPerformanceofEmbankmentsonVerySoftSoils’
CRCPress/Balkema,Taylor&FrancisGroup,aninformabusiness
©2013Taylor&FrancisGroup,London,UK
OriginallypublishedinPortugueseas‘AterrossobreSolosMoles’
©2009OficinadeTextos,EditoraSignerLtda,SãoPaulo,Brazil
Englishedition‘DesignandPerformanceofEmbankmentsonVerySoftSoils’
CRCPress/Balkema,Taylor&FrancisGroup,aninformabusiness
©2013Taylor&FrancisGroup,London,UK
Allrightsreserved
TypesetbyMPSLimited,Chennai,India
PrintedandBoundbyCPIGroup(UK)Ltd,Croydon,CR04YY
Allrightsreserved.Nopartofthispublicationortheinformationcontained
hereinmaybereproduced,storedinaretrievalsystem,ortransmittedinany
formorbyanymeans,electronic,mechanical,byphotocopying,recordingor
otherwise,withoutwrittenpriorpermissionfromthepublisher.
Althoughallcareistakentoensureintegrityandthequalityofthispublication
andtheinformationherein,noresponsibilityisassumedbythepublishersnor
theauthorforanydamagetothepropertyorpersonsasaresultofoperation
oruseofthispublicationand/ortheinformationcontainedherein.
Appliedfor
Publishedby: CRCPress/Balkema
P.O.Box11320,2301EH,Leiden,TheNetherlands
e-mail:[email protected]
www.crcpress.com–www.taylorandfrancis.com
ISBN:978-0-415-65779-2(Hbk)
ISBN:978-0-203-65779-9(eBook PDF)
To Maria,Adriana and Leandro for their continued
support over the years.
Márcio
To my family and students.
Esther
TThhiiss ppaaggee iinntteennttiioonnaallllyy lleefftt bbllaannkk
Table of contents
Preface xi
Abouttheauthors xiii
Acknowledgements xv
Listofsymbols xvii
Introduction xxvii
1 Constructionmethodsofembankmentsonsoftsoils 1
1.1 Replacementofsoftsoilsanddisplacementfills 1
1.1.1 Replacementofsoftsoils 1
1.1.2 Displacementfills 3
1.2 Conventionalembankmentwithtemporarysurcharge 5
1.3 Embankmentsbuiltinstages,embankmentswithlateralbermsand
reinforcedembankments 6
1.4 Embankmentonverticaldrains 6
1.5 Lightweightfills 7
1.6 Embankmentsonpile-likeelements 9
1.7 Constructionmethodologiesforharborworks 9
1.8 Finalremarks 12
2 Siteinvestigation 15
2.1 Preliminaryinvestigations 15
2.1.1 Borings 15
2.1.2 Characterization 17
2.2 Complementaryinvestigations 18
2.2.1 Insitutests 19
2.2.2 Laboratorytests 19
2.3 Vanetests 21
2.3.1 Equipmentandprocedures 21
2.3.2 Undrainedstrength 21
2.3.3 Claysensitivity 22
2.3.4 Stresshistory 24
2.3.5 Clayanisotropy 24
2.3.6 Testcorrection 25
2.4 Piezoconetest 26
2.4.1 Equipmentandprocedures 26
2.4.2 Correctionofconeresistance 26
viii Table of contents
2.4.3 Preliminarysoilclassification 27
2.4.4 Undrainedstrength(S ) 27
u
2.4.5 Stresshistory 29
2.4.6 Coefficientofconsolidation 31
2.5 T-bartest 33
2.6 Soilsamplingforlaboratorytests 33
2.7 Oedometerconsolidationtests 34
2.7.1 Otherconsolidationtests 35
2.7.2 Samplequality 35
2.8 Triaxialtests 38
2.9 Finalremarks 38
3 Geotechnicalpropertiesofverysoftsoils:RiodeJaneirosoftclays 41
3.1 Overallbehaviorofverysoftsoils:Camclaymodels 41
3.1.1 Stressandstrainvariables 41
3.1.2 Modelparameters 42
3.1.3 Yieldconditions 45
3.2 IndexpropertiesofsomeRiodeJaneiroclays 47
3.3 Compressibilityandstresshistory 49
3.3.1 Compressibility 49
3.3.2 Overconsolidationratio(OCR) 50
3.4 Hydraulicconductivityandcoefficientofconsolidation 50
3.5 Soilstrength 52
3.5.1 Undrainedstrength–laboratoryandinsitudata 52
3.5.2 Effectivestrengthparameters 54
3.6 Deformationdata 55
3.7 Viscousbehavior 56
3.7.1 Strainrateduringshearing 56
3.7.2 Strainrateduringconstantloadingoedometertests 56
3.8 Fieldstudies 58
3.8.1 EmbankmentI 58
3.8.2 EmbankmentII 59
4 Predictionofsettlementsandhorizontaldisplacements 63
4.1 Typesofsettlements 63
4.1.1 Immediatesettlement 64
4.1.2 Primaryconsolidationsettlements 64
4.1.3 Secondarycompressionsettlement 72
4.2 Stagedembankmentsettlements 76
4.3 Predictionofhorizontaldisplacements 79
4.4 Finalremarks 82
5 Accelerationofsettlements:useofverticaldrainsandsurcharge 83
5.1 Embankmentsonverticaldrains 83
5.2 Verticaldrains 84
5.2.1 Theoreticalsolutions 84
5.2.2 Consolidationwithpurelyradialdrainage 85
5.2.3 DiameterofinfluenceandequivalentdiameterofPVDs 86
Table of contents ix
5.2.4 Consolidationwithcombinedradialandverticaldrainage 87
5.2.5 InfluenceofsmearinPVDperformance 88
5.2.6 Influenceofmandrelsizeonsoildisturbance 88
5.2.7 Parametersforconsiderationofdisturbance(smear) 89
5.2.8 Theeffectofwellresistance 91
5.2.9 SpecificationofPVD 92
5.2.10 Sequenceforradialdrainagecalculations 92
5.3 Designofthehorizontaldrainageblanket 93
5.4 Useoftemporarysurcharge 95
5.4.1 Useofsurchargewithandwithoutverticaldrains 96
5.4.2 Vacuumpreloading 97
5.4.3 Useofsurchargetominimizesecondarycompression
settlements 99
5.5 Finalremarks 100
6 Stabilityofunreinforcedandreinforcedembankments 103
6.1 Designparameters 103
6.1.1 Undrainedstrengthofclay 103
6.1.2 Embankmentstrength 104
6.1.3 Geosyntheticreinforcementparameters 106
6.2 Failuremodesofembankmentsonsoftsoils 111
6.3 Foundationfailure:Criticalheightofembankment 111
6.4 Globalstabilityanalysisofunreinforcedembankments 112
6.4.1 Circularfailuresurfaces 112
6.4.2 Non-circularfailuresurfaces 113
6.5 Reinforcedembankments 115
6.5.1 Effectsofreinforcement 115
6.5.2 Foundationfailure 116
6.5.3 Failureduetolateralslidingofembankment 116
6.5.4 Globalfailure 118
6.5.5 Definitionoftensileforceinreinforcement 118
6.6 Stabilityanalysisofstageconstructedembankments 120
6.6.1 Conceptualaspects 120
6.6.2 Undrainedstrengthoftheclayforstagedconstruction 120
6.6.3 Illustrationofstabilityanalysisofstagedconstruction 122
6.6.4 Considerationsonthestabilityanalysisforstaged
constructedembankments 124
6.7 Sequenceforstabilityanalysisofembankmentsonsoftsoils 124
6.7.1 Unreinforcedembankments 124
6.7.2 Reinforcedembankments 125
6.7.3 Reinforcedembankmentbuiltinstages 126
6.8 Finalremarks 126
7 Embankmentsonpile-likeelements 127
7.1 Piledembankmentswithgeosyntheticplatform 129
7.1.1 Theworkingplatformsettlementandoverallembankment
behavior 130
