Pavement design: Past, present, future, where is the … RILEM Interna.onal Conference on Mechanisms of Cracking and Debonding in Pavements (MCD2016) Pavement design: Past, present,

8thRILEMInterna.onalConferenceonMechanismsofCrackingandDebondinginPavements(MCD2016)

Pavement design: Past, present, future, where is the crack?

LaurentPorot

Workshop:Newapproachestoaddresspavementfailuremorerealis.callyinasphal.cpavementdesignmethods


• Aboutpavementengineering• Pavementdesignapproaches• Conclusions

DC to Richmond Road in 1919 – from the Asphalt Institute


Pavement engineering


Aim of pavement, why to design?

•  Theaimofpavementistoensureasafereliablejourneyforgoodsandpeoplewhateverthecondi.ons

RoadServiceability

PavementStructure

?Aneedtoconnect

4/99


Pavement design principle

•  Op.misetechnicallyandeconomicallywithvariousconstraints!!!!!

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Materials,structuretypeMaterialquality,localresources

Founda.onSoil,watertable

TrafficAADT,load,designlife,reliability

ClimateRainfall,High/

LowTemperature,

frost

ServicelevelSafety,

maintenance,reliability

Strain/Stressanalysis

Subbase

Baselayers

Toplayers


Pavement design mechanism

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• Boussinescq(1866)•  Infinitelayer•  Independentofmaterialcharacteris.cs

Stressσz/q0Stress spreadσz

Z/a

σz/q0

a

q0

interfaceboundorunbound

H1,E1,n1

Soil,En,nn

H2,E2,n2

E l a s . cmaterial

Loadq,radiusa

Hσt

σz

Material,E1,n1

Soil,E2,n2

• Hogg(1938)&Westegaard(1926)•  2layers•  Materialdependent(S.ffness)

•  Burmister(1943)•  Mul.layers•  LinearElas.cTheory•  Isotropic&horizontallyinfinitelayers

Wherearethecracks?


Analy=cal approach

Structure Material

εt<εadm

Loadmodel  EquivalentStandardAxleLoad

5msa

εadmµdef

Log(ε/ε6)=-bLog(N/106)

Modelling

Radius,Pressure

E2,H2,ν2

E1,H1,ν1

E3,H3,ν3

E4,H4,ν4

Andinterfaceboundingcondi.ons

  Typeofstructure

  Typeofmaterials

ε z

εt

σt ou ε t

σt ou

7/99

Wherearethecracks?


AASHTO Method (1993)

•  EmpiricalapproachbasedontheAASHOroadtest(endof50’s)

•  Standardaxleload8t•  Introduc.onof

•  PresentServiceabilityIndexPSI•  StructuralNumberSN•  Reliabilityfactor

• Usinggeneralregressionequa.onornomograph

8/99

[ ]8.07-log(MR)2.32

)1(109440.0

5.12.4log0.20-1)log(SN9.36S Z )Log(W

19.5

0R18 ×+

++

−Δ

++×+×=

SN

PSI

Wherearethecracks?


Bri=sh method

•  Empiricalapproach•  TRL1132from1982&TRL850from1997•  DMRBVolume7Sec.on2

•  Standardaxleload8t• Basedon

•  Conceptoflonglifepavementfor«indeterminatelife»•  Failurefromtopcrackingnotfromfa.gue

• Materialproper.es•  Modulus@20°C,5Hz

• Usingspecificchart

9/99

Wherearethecracks?


MEPDG philosophy

10/99

•  ToreplaceAASHTO1993focusmoreonperformances

• Progressiveapproachwithaccuracyofdata

Level3

Bydefaultdesign,User-selectedvalues

Level2

ClosetoAASHTO1993,User-selectedvaluesfromdatabase,Modulusassessedthroughbinder

Level1

Dynamicmodulusmastercurve,Sitespecifictrafficspectrum,Fielddeflexion

Wherearethecracks?


Shell Pavement Design Method

•  Longhistory•  From1963withdesigncharts•  1973withBISARand1978withSPDM

• BasedonBurmistermodel•  Materialmodel(BANDS)•  Structuremodel(BISAR)•  Climatecondi.onsandtrafficspectrum(SPDM)•  Thickness,rumng,overlaydesign(SPDM)

• Keyfeatures•  Healingfactor,layerbonding•  Noreliabilityfactor

11/99

Wherearethecracks?


French Pavement Design

12/


French context

• Heavystandardaxleload•  13t/axle

•  Severewinterin60s•  Importantpavementdegrada.ons

•  LCPCandthetechnicalnetwork•  Researchanddevelopmentfrombothprivateandpublic•  Fullscalepavementfacili.esinNantes

•  Tollhighwayframework•  Drivenbywholelifecyclecostop.misa.on

13/99

Earlydevelopmentofholis?cpavementdesignapproach


French method

•  Empirical-analy.calapproachbasedonanalysisofstrainandstressinamul.layermodelandfa.guelawwithfieldcalibra.on

• Materialcharacteris.csassessvialaboratorytest•  Modulus@15°C10Hz,•  Fa.gue@10°C25Hz

• Heavystandardaxleload13t• Userdefinedmethodwithcorrela.onfactors

εallow = (NE/106)b x(Eθ1/Eθ2)1/2 x 10-bδt x k4 x k5 x ε6 θ1

• UseofAlize-LCPCsooware*•  Userfriendlyfullycustomised(climate,road/airport)•  Designandoverlaydesign

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*hqp://www.itech-soo.com/alize/index.php?lang=en


Design criteria

•  Forsoilandunboundmaterialàver.calstrainontop

•  εvadm=AN-0.222 A=12000lowtraffic16000hightraffic

•  Forbituminousmaterialàhorizontalstrainattheboqom

•  εhadm=ε6(N/106)-1/b -1/baround5

•  Forhydraulicmaterialàhorizontalstrainattheboqom

•  σhadm=σ6(N/106)-1/b -1/baround12-13

15/99

Mostlyfa?guecriteria

Wherearethecracks?


Pavement design process

16/99

• Pavementdesignin5steps

3–Materials,Structuretypes,materialcharacteris.cs

1–Traffic,expressedinESAL

2–Founda?on,bearingcapacity

5–Frost/Thaw,verifica.on

FinalStructure,layers,thickness,construc.on,maintenance,...

4-Pavementdesign,usingchartsorsooware

Climate

Servicevalue

Structurevalue


Various loading configura=on

17/99

•  Standardroadaxleloading•  Axleload8.16t(18klb)•  Singletwinwheelaxle

R

d

Standardaxlemodelling(8.16t)

•  B777aircraogear•  Totalweight240-300t,13bars•  6wheelsgear


Sensi=ve analysis

18/99

Referencecase:

PF2

11GB2

12GB2

300truck/day20years

Unboundlayers:

PF2

11GB2

12GB2

300truck/day1year2months

Thicknessvaria.on

PF2

11GB2

10GB2

300truck/day11years

Weakfounda.on

PF1

11GB2

12GB2300truck/day10years

Debonding


Russian Pavement Design

19/


Russian context

• Oneoftheworldlargestcountry•  Variousclimatezonesfromcoldtosubtropical• Wideroadnetwork

•  Longhistoricalscien.ficbackground•  MADI(Московскийавтомобильнодорожныйгосударственный)

researchfacili.es•  Overlastdecadesmanyinnova.onsintroduced•  PartnershipswithLCPCbackin70s

20/99


Russian method

• Analy.calapproachinODN218.046.01(ГОСУДАРСТВЕННАЯСЛУЖБАДОРОЖНОГОХОЗЯЙСТВАМИНИСТЕРСТВАТРАНСПОРТАРОССИЙСКОЙФЕДЕРАЦИИ)

•  Mechanicaldesignand•  Freeze/thawresistance

• Materialcharacteris.csassessvialaboratorytest•  Specificjobmixformula,strengthat0°C,20°C,60°C•  Assump.onforothercharacteris.cs

• Differentclimatezones•  Trafficwith

•  differentstandardaxleloadupto115kN•  Numberofdaysperyeardependingonclimatezone

• Useofnomographsorsooware

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Design process

• Roadcategoryandtrafficclass•  5roadcategorieswithreliabilityfrom0.7to0.98•  Standardaxleloaddependsonroadcategoryandproject•  Totaltrafficfor70to205daysdependingclimatezones

• Mechanicalcalcula.on•  Totalpavementstrength,allowedtotaldeflexionlayerbylayer

•  Maximalstrengthonsubgradelayer(at20°C)•  Fa.gueresistanceofboundmaterials(stress)

•  Freeze/thawcalcula.on•  Totalfreezedepthdependingonclimatezone

22/99


Design criteria

•  Totalequivalenttrafficloading

•  Totalpavementstrength•  UseofnomographK=Ei/Ei-1•  Asphaltconcrete2000to3200MPa

• Maximalstrengthonthesubgrade•  2-layermodelwith•  Useofnomograph

•  Fa.gueresistance•  Useoftotalpavementstrength

•  Freezeresistance•  Freezedepth,useofdeepsandlayer

23/99

Wherearethecracks?


Conclusion

24/

Cut&FoldErikJohannsonh6p://www.erikjohanssonphoto.com/


Conclusion

•  Trendtowardsmoreanaly.calpavementdesignvs.empirical

• CommonfeaturesusingBurmistermul.-layermodel•  Elas.clinearmodelandfa.guelaw

• Wherearethecracks?•  Fa.gueresistanceaddressedinpavementdesign•  Debondingcanbeassessed•  Thermalcracking(lowtemperature)addressedwithasphaltmixdesign

• MoremodelinPavementManagementSystem•  HDM4,…

25/99

8thRILEMInterna.onalConferenceonMechanismsofCrackingandDebondinginPavements(MCD2016)Dimensionnement mécanique page 26

Wherearethecracks?

Documents

Pavement design: Past, present, future, where is the … RILEM Interna.onal Conference on Mechanisms of Cracking and Debonding in Pavements (MCD2016) Pavement design: Past, present,