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

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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