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  • Nebraska Transportation Center

    Report SPR-P1 (09) P320 Final Report

    Inspectors Manual for Mechanically Stabilized Earth Walls

    This report was funded in part through grant[s] from the Federal Highway Administration [and Federal Transit Administration], U.S. Department of Transportation. The views and opinions of the authors [or agency] expressed herein do not necessarily state or reflect those of the U. S. Department of Transportation.

    Nebraska Transportation Center262 WHIT2200 Vine StreetLincoln, NE 68583-0851(402) 472-1975

    26-1114-0023-001

    2009

    Wayne Jensen, Ph.D. Associate Professor The Charles W. Durham School of Architectural Engineering & Construction University of Nebraska-Lincoln

  • Inspectors Manual for Mechanically Stabilized Earth Walls

    Wayne Jensen, Ph.D. Associate Professor Durham School of Architectural Engineering and Construction University of Nebraska-Lincoln

    A Report Research Sponsored by

    Nebraska Department of Roads

    Nebraska Transportation Center

    June, 2009

  • ii

    Technical Report Documentation Page 1. Report No. SPR-P1(09) P320

    2. Government Accession No.

    3. Recipient's Catalog No.

    4. Title and Subtitle Inspectors Manual for Mechanically Stabilized Earth Walls

    5. Report Date June, 2010

    6. Performing Organization Code

    7. Author(s) Wayne Jensen

    8. Performing Organization Report No. SPR-P1(09) P320

    9. Performing Organization Name and Address University of Nebraska- Lincoln College of Engineering and Technology Lincoln, NE 68503

    10. Work Unit No. (TRAIS)

    11. Contract or Grant No.

    12. Sponsoring Agency Name and Address Nebraska Department of Roads 1500 Hwy. 2 Lincoln, NE 68502

    13. Type of Report and Period Covered July, 2008-June, 2009

    14. Sponsoring Agency Code MATC TRB RiP No. 17018

    15. Supplementary Notes

    16. Abstract The scope of the project is to develop a condition rating system, creation of an inspector's manual to reference during inspection or address any training for inspectors at the district level. The research project will develop a MSE wall condition rating system and incorporate this system into the database being developed and create training and reference manuals.

    17. Key Words Soil stabilization, Condition surveys, Mechanically stabilized earth, Manuals, Training, Referencing, Databases

    18. Distribution Statement

    19. Security Classif. (of this report) Unclassified

    20. Security Classif. (of this page) Unclassified

    21. No. of Pages 36

    22. Price

  • iii

    Disclaimer

    As the Nebraska Department of Roads did not require a final report for this research, a

    PowerPoint presentation was adapted for publishing a final report.

  • Glossary

    Coping

    Thecopingisusedatthetopofthewallpanelstoprovideanaestheticfinishtothewalltop.Copingcanbecastinplaceorprefabricated.Geotextile Fabric(Filter)

    Geotextile fabric(filter)isusedtocoverthebacksideofthejointsbetweenwallpanels.Fabrickeepssoilfrommovingthroughthejointswhileallowinganyexcesswatertodrain.BasePad

    Thebasepad(levelingpad)isanonreinforcedconcretepadusedtoprovidealevel,consistentsurfaceattheproperelevation.RandomBackfill

    RandombackfillismaterialderivedfromexcavationduringconstructionoftheMSEwall.SelectBackfill

    Selectbackfillisfillthatmeetsgradation,corrosion,unitweight,internalfrictionangleand/orotherrequirementsforaspecificMSEwall.Reinforcement

    Soilreinforcementholdsthewallfaceinpositionandreinforcesthesoildirectlybehindthepanels.Soilreinforcementcanbestrips,grids,ormesh.Reinforcementcanbemadeofsteel(inextensible)orpolymers(extensible).Spacers

    Wallpanelspacersaretypicallyribbedelastomericorpolymericpads.Theyareinsertedbetweenpanelstomitigatepaneltopanelcontactandensure properspacing.Properspacingkeepsthepanelsfromhavingpointcontactandspallingtheconcrete.Somewallsareconstructedwithoutspacers.WallFacingPanels

    Wallfacingpanelsareusedtoholdthesoilinplace behind thefaceofthewall.Panelsaretypicallyconcretebuttheycanbemetal,wood,block,meshorothermaterials.

    1

  • LocatingtheDesiredWall

    MSEWallIDNumberingConvention

    1. 2. 3. 4.

    M008018215L

    1.Indicatesthetypeofwallpresent.MindicatesaMSEwall,whileRindicatesaretainingorgravitywall.2Indicatesthehighwaynumberassociatedwithaspecificwall.TheMSEwall(s)form(s)onelateralboundaryofthishighway.Fourspacesareprovided.Ifthehighwaynumberisa2digitnumber,addtwo0asplaceholdersbeforethehighwaynumber(asillustratedaboveforI80).3.ThesefivedigitsindicatetheReferencePostlocationclosesttothecenterofthewall.4.Thelastdigitisusedtodesignatewhichsideofthehighwaythewallislocatedonwhentheinspectorisfacinginthedirectionofascendingreferenceposts.

    2

  • TherearemanydifferencescenarioswhereMSEorretainingwallsarepresent.Thefollowingexamplesdescribesomeofthemostcommonscenarios.InstructionsonhowtoassignIDnumberstospecificwallsareshownforeachscenario.

    Scenario1 SecondaryRoadBridgeOveraHighwayorInterstate

    Thisfigureshowsasituationwhereacountybridgepassesoveraninterstatehighway.ThecenterofbothwallsislocatedatapproximatelyRP182.15onInterstate80.Inthissituation,thewallidentificationnumberisthesame,exceptforthelastdigit(RorL),whichindicateswhetherthespecificwallistotheleftorrightwhenfacinginthedirectionofascendingRPnumbers.

    M008018215R

    RP182.15(CenterofWalls)

    M008018215L

    I80BeneathaSecondaryRoad

    DirectionofAscendingRP

    SecondaryRoad

    3

  • Scenario2 StandAloneWallAlongaHighway

    RP182.27

    Thisfigureshowsastandalonewallalongonesideofahighway.ThecenterofthewallislocatednearestRP182.27andthewallistotherightwhenfacinginthedirectionofascendingreferencepostnumbers.IfthewallwasaretainingwallinsteadofaMSEwall,thefirstcharacterwouldbeRinlieuofMandthenomenclaturewouldreadR003018227R.

    DirectionofAscendingRP

    Hwy30

    MSEWallM003018227R

    4

  • Scenario3 HighwayOveraSecondaryRoad,StreamorRailroad

    Thisfigureshowsasituationwhereahighwaypassesoverasecondaryroad,streamorrailroad.ThecenterofonewallislocatednearRP121.32(onUS136)whilethecenteroftheotherwallislocatednearRP121.34(onUS136).Inthissituation,thewallidentificationnumbercorrespondstothelocationofeachspecificwallscenterwithregardtoreferencepostsalongthenumberedhighway.RandLarenotused.Wingwalls,whichmaybeMSEorretainingwalls,areconsideredtobecomponentsofeachprimarywall.

    SecondaryRoad,StreamorRailroad

    DirectionofAscendingRP

    RP121.34(onUS136)RP121.32(onUS136)

    US136

    SecondaryRoad,StreamorRailroad

    DirectionofAscendingRP

    M013612132 M013612134

    5

  • Scenario4 TwoHighwaysCrossing

    Thisfigureshowsasituationwheretwohighwayscross.ThecenterofbothwallsislocatedatapproximatelyRP59.87onUS77.Inthissituation,theNorthSouthhighwayisthebasisforwallnomenclature.Thewallidentificationnumberisthesame,exceptforthelastdigit(RorL),whichindicateswhetherthatspecificwallistotheleftortotherightwhenfacinginthedirectionofascendingRPnumbersalongtheNorthSouthhighway.

    US77(NS)

    NE30(EW)

    DirectionofAscen

    ding

    RP

    US77

    (NS)

    RP59.87(onUS77)

    M007705987RM007705987L

    6

  • Scenario5 MultipleWallsWhereHighwaysCross/Merge

    Thisfigureshowsasituationwheretwohighwayscrossormerge.ThecenterofonesetofwallsislocatednearRP89.44onUS275.ThecenteroftheothersetofwallsislocatednearRP89.46onUS275.Inthissituation,theNorthSouthhighwayisagainthebasisforwallnomenclature.Thewallidentificationnumberwithineachsetofwallsisthesame,exceptforthelastdigit(RorL),whichindicateswhetherthatspecificwallistotheleftorrightwhenfacinginthedirectionofascendingRPnumbersalongtheNorthSouthhighway.

    RP89.44

    RP89.46

    M027508944R

    M027508946R

    M027508944L

    M0275089446L

    US 275

    (N-S)

    Hwy2(EW)

    DirectionofAscen

    ding

    RP

    7

  • RandomBackfill

    CopingWallFacing(Panels)

    GeotextileFabricFilter

    WallReinforcement(DashedLines)

    MechanicallyStabilizedSoil(SelectBackfill)

    BasePad

    OriginalSoil

    MajorComponentsofaMSEWall

    8

  • WallTilting

    Apanelwallshowingapositivetilt.

    Definition:PanelWalls:Inclinationofthewallfacefromverticalorfromitsoriginalinclination.

    ModularBlock&GravityWalls:Modularblockwallsoftenexhibitnegativetiltduetothesetbackofeachsuccessivelayerofblocks.Gravitywallsaregenerallyconstructedwithaslightnegativetilt.

    9

  • WallTilting

    PanelWalls:

    0 Asectionofortheentirewallhasfailedduetotilting.

    1 Asectionofortheentirewallisinclinedtotheextentthatseparationofpanelsisbeginningtooccurinthewallface.

    3 Asectionofortheentirewallisinclinedoutwardat10o (2inchesHorizontal:12inchesVertical)to15o (3inchesHorizontal:12inchesVertical).

    5 Asectionofortheentirewallisinclinedoutwardat5o (1inchHorizontal:12inchesVertical)to10o (2inchesHorizontal:12inchesVertical).

    7 Asectionofortheentirewallisinclinedoutwardat0o5o (1inchHorizontal:12inchesVertical).

    9 Thereisnochangeinwallinclinationfromconstructionspecifications.

    BlockWalls:

    0 Blockwallhaspositiveinclination.

    5 Blockwallisvertical(ithasnotilt).

    9 Blockwallhasnegativeinclination.

    10

  • StructuralCracking

    Separationofthecornerofaprecastpanelasaresultofstructuralcracking.

    Definition:Structuralcrackingischaracterizedbyaseparationwhichpenetratesthroughtheentiredepthofthewallface.Acrackwhichdoesnotextendthroughtheentirethicknessofthewallfaceshouldbe

    characterizedasfacialdeterioration.

    11

  • StructuralCracking

    0Morethan50%ofwallareashowsstructuralcracking.

    1 Between33 50%ofwallareashowsstructura