U.S. Department of Transportation Publication No. FHWA NHI-07-071 Federal Highway Administration June 2008 NHI Course No. 132036__________________________________ Earth Retaining Structures Reference Manual

National Highway Institute

NOTICE The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect policy of the Department of Transportation. This report does not constitute a

standard, specification, or regulation. The United States Government does not endorse products or manufacturers. Trade or manufacturer's names appear herein only

because they are considered essential to the objective of this document.

Technical Report Documentation Page 1. REPORT NO. FHWA-NHI-07-071

2. GOVERNMENT ACCESSION NO.

3. RECIPIENT'S CATALOG NO.

5. REPORT DATE

June 2008

4. TITLE AND SUBTITLE Earth Retaining Structures

6. PERFORMING ORGANIZATION CODE

7. AUTHOR(S) Burak F. Tanyu, Ph.D. and Paul J. Sabatini, P.E., Ph.D, and Ryan R. Berg, P.E.

8. PERFORMING ORGANIZATION REPORT NO.

10. WORK UNIT NO.

9. PERFORMING ORGANIZATION NAME AND ADDRESS Ryan R. Berg & Associates, Inc. 2190 Leyland Alcove Woodbury, MN 55125

11. CONTRACT OR GRANT NO. DTFH61-06-D-00019 13. TYPE OF REPORT & PERIOD COVERED

12. SPONSORING AGENCY NAME AND ADDRESS National Highway Institute Federal Highway Administration U.S. Department of Transportation Washington, D.C.

14. SPONSORING AGENCY CODE

15. SUPPLEMENTARY NOTES This manual is the updated version of FHWA NHI-99-025 manual prepared by Parsons Brinckerhoff Quade & Douglas, Inc., authored by G. A. Munfakh, N. C. Samtani, R. J. Castelli, and J. Wang. This updated version presents design procedures for walls, except in-situ reinforced walls, using the load and resistance factor design (LRFD) method. FHWA COTR Louisa M. Ward FHWA Technical Consultants J. DiMaggio, B. Siel, and D. Alzamora. 16. ABSTRACT This is the reference manual for FHWA NHI course No. 132036 on Earth Retaining Structures. Detailed information on subsurface investigation, soil and rock property design parameter selection, lateral earth pressures for wall system design, and load and resistance factor design (LRFD) for retaining walls are provided. Wall types discussed include gravity and semi-gravity walls, modular gravity walls, MSE walls, nongravity cantilever walls and anchored walls, and in-situ reinforced walls. Information on wall system feasibility and selection, construction materials and methods, cost information, design and performance information, and required elements of construction inspection are presented for each wall type. Different contracting approaches for the various wall systems are also discussed. 17. KEY WORDS lateral earth pressures, LRFD, gravity and semi-gravity walls, modular gravity walls, mechanically stabilized earth walls, sheet pile walls, soldier pile and lagging walls, slurry walls, tangent/secant walls, anchored walls, soil nailing, micropiles, wall selection, and contracting approaches.

18. DISTRIBUTION STATEMENT No restrictions.

19. SECURITY CLASSIF. Unclassified

20. SECURITY CLASSIF. Unclassified

21. NO. OF PAGES 764

22. PRICE

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SI CONVERSION FACTORS APPROXIMATE CONVERSIONS FROM SI UNITS

Symbol When You Know Multiply By To Find Symbol

LENGTH mm m m km

millimeters meters meters

kilometers

0.039 3.28 1.09 0.621

inches feet

yards miles

in ft yd mi

AREA mm2 m2 m2 ha

km2

square millimeters square meters square meters

hectares square kilometers

0.0016 10.764 1.195 2.47 0.386

square inches square feet

square yards acres

square miles

in2 ft2 yd2 ac mi2

VOLUME ml l

m3 m3

millimeters liters

cubic meters cubic meters

0.034 0.264 35.71 1.307

fluid ounces gallons

cubic feet cubic yards

fl oz gal ft3 yd3

MASS g

kg tonnes

grams kilograms

tonnes

0.035 2.202 1.103

ounces pounds

tons

oz lb

tons TEMPERATURE

EC Celsius 1.8 C + 32 Fahrenheit EF WEIGHT DENSITY

kN/m3 kilonewton / cubic meter 6.36 poundforce / cubic foot pcf FORCE and PRESSURE or STRESS

N kN kPa kPa

newtons kilonewtons kilopascals kilopascals

0.225 225

0.145 20.9

poundforce poundforce

poundforce / square inch poundforce / square foot

lbf lbf psi psf

PREFACE This document is the update of the 1999 NHI course manual for NHI Course 13236 Module 6, Earth Retaining Structures. This document has been written to provide up-to-date information on earth retaining systems currently being constructed in the United States for highway applications. Earth retaining systems discussed in this manual include:

Rigid gravity and semi-gravity walls; Prefabricated modular gravity walls; Mechanically stabilized earth (MSE) walls; Non-gravity cantilevered and anchored walls including sheet-pile walls, soldier

beam and lagging walls, slurry walls, tangent and secant pile walls, soil mixed walls, and jet-grouted walls; and

In-situ reinforced walls including soil nail walls and micropile walls. This document is a synthesis of practical information on selection, construction, design, cost, and construction inspection for these wall systems. In addition, information on subsurface investigation, soil and rock design parameter selection, and lateral earth pressure evaluation applied specifically to wall systems, and LRFD methods for retaining walls is provided. The design procedures presented in this manual are consistent with the AASHTO LRFD Bridge Design Specifications (AASHTO, 2007). Significant portions of this manual are based on the following FHWA references:

Mechanically Stabilized Earth Walls and Reinforced Soil Slopes Design and Construction Guidelines, by V. Elias, B.R. Christopher and R.R. Berg, FHWA NHI-00-043.

Design and Construction Monitoring of Soil Nail Walls, by R. J. Byrne, D. Cotton, J.Porterfield, C. Wolschlag and G. Ueblacker, FHWA-SA-96-069.

Earth Retaining Systems, Geotechnical Engineering Circular No. 2, by P.J. Sabatini, V. Elias, G.R. Schmertmann, and R. Bonaparte, FHWA- SA-96-038.

Ground Anchors and Anchored Systems, Geotechnical Engineering Circular No. 4, by P.J. Sabatini, D. Pass, and R.C. Bachus, FHWA- SA-99-015.

Evaluation of Soil and Rock Properties, Geotechnical Engineering Circular No. 5, by P.J. Sabatini, R.C. Bachus, P.W. Mayne, J.A. Schneider, and T.E. Zettler, FHWA- IF-02-034.

Soil Nail Walls, Geotechnical Engineering Circular No. 7, by C.A. Lazarte, V. Elias, R.D. Espinoza, and P.J. Sabatini, FHWA-IF-03-017.

Subsurface Investigations, by. P.W. Mayne, B.R. Christopher, and J. DeJong, FHA NHI-01-031.

The authors recognize the efforts of Barry Siel, Daniel Alzamora, and Jerry A. DiMaggio who served as FHWA Technical Consultants for this work.

The authors further acknowledge the efforts of the following individuals who provided valuable technical input during the development of this manual.

Craig Actis FHWA Resource Center Tom Armour DBM Contractors Donald Bruce Geosystems, L.P. Barry Christopher Christopher Consultants James Collin The Collin Group Dave Davis Northstar Vinyl Inc. Leo Fontaine Connecticut DOT Jeff Horsfall Wisconsin DOT Scott Ludlow Earth Exploration Inc. Steve Maxwell Wisconsin DOT Peter Osborn FHWA Bruce Pfister Wisconsin DOT Ray Poletto Mueser Rutledge Consulting Engineers Dan Priest Contech Construction Products Tom Richards Nicholson Construction Company Ray Sandiford - Port Authority of New York and New Jersey Brian Sweeney - Haley & Aldrich, Inc. Trevor Wang Colorado DOT Rob Wendt North American Steel Sheet Piling Association Joe Wiedemann Berkel and Company Contractors John Wolosick Hayward Baker, Inc. David Yang Ratio, Inc.

FHWA NHI-07-071 i June 2008 Earth Retaining Structures

TABLE OF CONTENTS

CHAPTER 1 INTRODUCTION....................................................................................................................... 1-1 1.1 PURPOSE AND SCOPE.............................................................................................................. 1-1 1.2 HISTORY OF EARTH RETAINING SYSTEMS ....................................................................... 1-2 1.3 CLASSIFICATION OF EARTH RETAINING STRUCTURES................................................. 1-4

1.3.1 Classification by Load Support Mechanism ................................................................... 1-5 1.3.2 Classification by Construction Concept.......................................................................... 1-5 1.3.3 Classification by System Rigidity................................................................................... 1-7 1.3.4 Temporary and Permanent Wall Applications................................................................ 1-7

1.4 ORGANIZATION OF THE MANUAL....................................................................................... 1-8 1.5 PRIMARY REFERENCES FOR THIS MANUAL ..................................................................... 1-9

CHAPTER 2 EVALUATION OF GEOTECHNICAL PARAMETERS FOR EARTH RETAINING

SYSTEMS.................................................................................................................................... 2-1 2.1 INTRODUCTION ........................................................................................................................ 2-1 2.2 PLANNING A SUBSURFACE INVESTIGATION AND LABORATORY TESTING

PROGRAM .................................................................................................................... 2-2 2.2.1 General .......................................................................................................................... 2-2 2.2.2 Identify Data Needs and Review Available Information................................................ 2-2 2.2.3 Developing a Site Investigation Program ....................................................................... 2-4 2.2.4 Sampling Methods .......................................................................................................... 2-9 2.2.5 Developing a Laboratory Testing Program....................................................................2-11

2.3 FUNDAMENTAL CONCEPTS OF SHEAR STRENGTH ........................................................2-13 2.3.1 General .........................................................................................................................2-13 2.3.2 Drained Versus Undrained Loading ..............................................................................2-13 2.3.3 Drained Stress-Strain-Strength Behavior.......................................................................2-14 2.3.4 Undrained Stress-Strain-Strength Behavior...................................................................2-17 2.3.5 Effective Stress Parameters ...........................................................................................2-18 2.3.6 Total Stress Parameters..................................................................................................2-18

2.4 LABORATORY INDEX TESTS ................................................................................................2-19 2.4.1 General .........................................................................................................................2-19 2.4.2 Moisture Content ...........................................................................................................2-19 2.4.3 Unit Weight ...................................................................................................................2-20 2.4.4 Atterberg Limits.............................................................................................................2-20 2.4.5 Particle Size Distribution ...............................................................................................2-21 2.4.6 Laboratory Classification...............................................................................................2-22 2.4.7 Specific Gravity .............................................................................................................2-22 2.4.8 Organic Content.............................................................................................................2-22

2.5 PARAMETERS FOR BACKFILL SOILS ..................................................................................2-23 2.5.1 General .........................................................................................................................2-23 2.5.2 Classification of Backfill Soils ......................................................................................2-23 2.5.3 Unit Weight ...................................................................................................................2-24 2.5.4 Backfill Shear Strength Parameters ...............................................................................2-25 2.5.5 Electrochemical Parameters of Backfill Soils................................................................2-26 2.5.6 Placement and Compaction of Backfill Soils ................................................................2-26

FHWA NHI-07-071 ii June 2008 Earth Retaining Structures

2.5.7 Backfill Soil Permeability..............................................................................................2-30 2.5.8 Filtration Requirements .................................................................................................2-31 2.5.9 Other Backfill Materials ................................................................................................2-34

2.6 PARAMETERS FOR IN-SITU SOILS .......................................................................................2-37 2.6.1 General .........................................................................................................................2-37 2.6.2 Stratigraphy ...................................................................................................................2-37 2.6.3 Unit Weight ...................................................................................................................2-38 2.6.4 Shear Strength Parameters .............................................................................................2-39 2.6.5 Consolidation Parameters ..............................................................................................2-44 2.6.6 Electrochemical Parameters...........................................................................................2-53 2.6.7 Permeability...................................................................................................................2-53

2.7 ROCK PARAMETERS ...............................................................................................................2-56 2.7.1 General .........................................................................................................................2-56 2.7.2 Rock Mass Classification...............................................................................................2-56 2.7.3 Compressive Strength of Intact Rock ............................................................................2-69 2.7.4 Smooth Discontinuity ....................................................................................................2-71 2.7.5 Rough Discontinuity......................................................................................................2-72 2.7.6 Infillings.........................................................................................................................2-72 2.7.7 Shear Strength of Fractured Rock Masses .....................................................................2-73 2.7.8 Permeability...................................................................................................................2-77

CHAPTER 3 LATERAL EARTH AND WATER PRESSURES................................................................... 3-1

3.1 INTRODUCTION ........................................................................................................................ 3-1 3.2 EARTH PRESSURE THEORY ................................................................................................... 3-2

3.2.1 Active and Passive Earth Pressures ................................................................................ 3-2 3.2.2 At-Rest Earth Pressure.................................................................................................... 3-5 3.2.3 Rankine Earth Pressure Theory ...................................................................................... 3-6 3.2.4 Coulomb Earth Pressure Theory..................................................................................... 3-8 3.2.5 Effect of Wall Friction on Earth Pressures ..................................................................... 3-8 3.2.6 Equivalent Fluid Pressure ..............................................................................................3-11

3.3 TEMPORARY CONDITIONS....................................................................................................3-13 3.3.1 General .........................................................................................................................3-13 3.3.2 Softening........................................................................................................................3-13 3.3.3 Tension Cracks ..............................................................................................................3-14 3.3.4 Soil Fabric......................................................................................................................3-15

3.4 PERMANENT CONDITIONS....................................................................................................3-16 3.5 INFLUENCE OF MOVEMENT ON EARTH PRESSURES......................................................3-17

3.5.1 General .........................................................................................................................3-17 3.5.2 Magnitude of Movement Needed to Mobilize Limit Pressures .....................................3-17 3.5.3 Flexibility of the Wall....................................................................................................3-18 3.5.4 Influence of Movement on Soil Properties ....................................................................3-18

3.6 DESIGN EARTH AND WATER PRESSURES .........................................................................3-21 3.6.1 Wall Friction and Adhesion...........................................................................................3-21 3.6.2 Earth Pressure Coefficients............................................................................................3-22 3.6.3 Theoretical Earth Pressures in Stratified Soils...............................................................3-27 3.6.4 Semi Empirical Earth Pressure Diagrams......................................................................3-28

FHWA NHI-07-071 iii June 2008 Earth Retaining Structures

3.6.5 Design Water Pressures .................................................................................................3-32 3.7 EARTH PRESSURE FROM SURCHARGE LOADS ................................................................3-36

3.7.1 General .........................................................................................................................3-36 3.7.2 Uniform Surcharge Loads..............................................................................................3-36

3.8 EARTH PRESSURES DUE TO COMPACTION.......................................................................3-37 3.9 EARTH PRESSURES RESULTING FROM SILO EFFECT.....................................................3-40 3.10 EARTH PRESSURES RESULTING FROM SEISMIC FORCES .............................................3-41

3.10.1 General .........................................................................................................................3-41 3.10.2 Seismic Earth Pressures .................................................................................................3-41 3.10.3 Displacement Approach.................................................................................................3-46

3.11 LATERAL EARTH PRESSURES IN COHESIVE BACKFILLS..............................................3-47 3.12 LOADS FROM JOINTED ROCK MASSES ..............................................................................3-49 3.13 EXAMPLE PROBLEMS.............................................................................................................3-49

3.13.1 Example Problem 1........................................................................................................3-50 3.13.2 Example Problem 2........................................................................................................3-51 3.13.3 Example Problem 3........................................................................................................3-52

CHAPTER 4 LOAD RESISTANCE FACTOR DESIGN FOR EARTH RETAINING SYSTEMS........... 4-1

4.1 INTRODUCTION ........................................................................................................................ 4-1 4.2 CONCEPT OF LIMIT STATES................................................................................................... 4-2 4.3 COMMON LIMIT STATES IN ERS DESIGN............................................................................ 4-3 4.4 LOAD COMBINATIONS IN LIMIT STATES ........................................................................... 4-3 4.5 EVALUATION OF RESISTANCE FACTORS........................................................................... 4-4

CHAPTER 5 CAST-IN-PLACE (CIP) GRAVITY AND SEMI-GRAVITY WALLS................................. 5-1

5.1 INTRODUCTION ........................................................................................................................ 5-1 5.2 TYPES OF SEMI-GRAVITY CIP WALLS................................................................................. 5-3

5.2.1 Cantilever........................................................................................................................ 5-3 5.2.2 Counterfort Walls ........................................................................................................... 5-5 5.2.3 Buttress Walls................................................................................................................. 5-6 5.2.4 Other CIP Semi-Gravity Walls ....................................................................................... 5-6

5.3 WALL CONSTRUCTION ........................................................................................................... 5-8 5.4 COST ........................................................................................................................................ 5-9 5.5 WALL DESIGN ..........................................................................................................................5-10

5.5.1 Steps 1, 2, and 3.............................................................................................................5-10 5.5.2 Step 4 Select Base Dimension ....................................................................................5-12 5.5.3 Step 5 Select Lateral Earth Pressure Distribution .......................................................5-12 5.5.4 Step 6 Evaluate Factored Loads..................................................................................5-13 5.5.5 Step 7 - Evaluate Bearing Resistance ............................................................................5-17 5.5.6 Step 8 Check Eccentricity...........................................................................................5-19 5.5.8 Step 10 Evaluate Overall Stability..............................................................................5-21 5.5.9 Step 11 Estimate Maximum Lateral Wall Movement, Tilt, and Wall Settlement at the

Service I Limit State........................................................................................5-21 5.5.10 Step 12 Design Wall Drainage Systems .....................................................................5-23

5.6 CONSTRUCTION INSPECTION...............................................................................................5-29

FHWA NHI-07-071 iv June 2008 Earth Retaining Structures

CHAPTER 6 MODULAR GRAVITY WALLS .............................................................................................. 6-1 6.1 INTRODUCTION ........................................................................................................................ 6-1 6.2 CRIB WALLS .............................................................................................................................. 6-4

6.2.1 General .......................................................................................................................... 6-4 6.2.2 Wall Construction........................................................................................................... 6-4 6.2.3 Materials ......................................................................................................................... 6-6 6.2.4 Cost .......................................................................................................................... 6-7

6.3 CONCRETE MODULE WALLS................................................................................................. 6-8 6.3.1 General .......................................................................................................................... 6-8 6.3.2 Wall Construction........................................................................................................... 6-8 6.3.3 Materials ........................................................................................................................6-11 6.3.4 Cost .........................................................................................................................6-11

6.4 GABION WALLS .......................................................................................................................6-12 6.4.1 General .........................................................................................................................6-12 6.4.2 Wall Construction..........................................................................................................6-13 6.4.3 Materials ........................................................................................................................6-14 6.4.4 Cost .........................................................................................................................6-17

6.5 BIN WALLS................................................................................................................................6-17 6.5.1 General .........................................................................................................................6-17 6.5.2 Wall Construction..........................................................................................................6-18 6.5.3 Materials ........................................................................................................................6-23 6.5.4 Cost .........................................................................................................................6-23

6.6 MODULAR GRAVITY WALL DESIGN ..................................................................................6-23 6.6.1 General .........................................................................................................................6-23 6.6.2 Lateral Earth Pressures ..................................................................................................6-25 6.6.3 Sliding .........................................................................................................................6-25 6.6.4 Limiting Eccentricity .....................................................................................................6-27 6.6.5 Bearing Resistance.........................................................................................................6-28 6.6.6 Structural Capacity of Wall Modules ............................................................................6-29 6.6.7 Lateral and Vertical Displacements at the Service Limit State......................................6-29 6.6.8 Overall Stability at the Service Limit State ...................................................................6-29 6.6.9 Gabion Walls .................................................................................................................6-30

6.7 EXAMPLE PROBLEM...............................................................................................................6-30 6.8 CONSTRUCTION INSPECTION...............................................................................................6-34 6.9 T-WALLS....................................................................................................................................6-36

6.9.1 Overview .......................................................................................................................6-36 6.9.2 T-Wall Construction ......................................................................................................6-38 6.9.3 T-Wall Cost ...................................................................................................................6-38 6.9.4 T-Wall Design ...............................................................................................................6-38

CHAPTER 7 MECHANICALLY STABILIZED EARTH WALLS ............................................................. 7-1

7.1 INTRODUCTION ........................................................................................................................ 7-1 7.2 PRINCIPAL COMPONENTS OF MSE WALLS ........................................................................ 7-2 7.3 APPLICATIONS OF MSE WALLS ............................................................................................ 7-5 7.4 MATERIALS FOR MSE WALLS ............................................................................................... 7-9

7.4.1 Backfill Material ............................................................................................................. 7-9

FHWA NHI-07-071 v June 2008 Earth Retaining Structures

7.4.2 Reinforcing Elements ....................................................................................................7-12 7.4.3 Wall Facing Elements....................................................................................................7-15

7.5 MSE WALL CONSTRUCTION .................................................................................................7-19 7.5.1 Construction of MSE Walls with Precast Facings .........................................................7-21 7.5.2 Construction of MSE Walls with Flexible Facings .......................................................7-22 7.5.3 Backfill Placement and Compaction..............................................................................7-25

7.6 MSE WALL COST......................................................................................................................7-27 7.7 CONSTRUCTION INSPECTION OF MSE WALLS.................................................................7-29 7.8 MSE WALL DESIGN .................................................................................................................7-32

7.8.1 Initial Design Steps (Steps 1 through 3) ........................................................................7-35 7.8.2 Strength Limit States External Stability (Steps 4 through 8) ......................................7-36 7.8.3 Strength Limit States Internal Stability (Steps 9 through 13) .....................................7-48 7.8.4 Service Limit States (Steps 14 and 15) ..........................................................................7-69 7.8.5 Design of Wall Drainage Systems (Step 16) .................................................................7-72 7.8.6 Additional Design Considerations .................................................................................7-74

7.9 MSE WALL EXAMPLE PROBLEM .........................................................................................7-76 7.9.1 Problem Statement.........................................................................................................7-76 7.9.2 Solution of the Problem .................................................................................................7-77

CHAPTER 8 NONGRAVITY CANTILEVERED AND ANCHORED WALLS......................................... 8-1

8.1 INTRODUCTION ........................................................................................................................ 8-1 8.2 SHEET PILE WALLS.................................................................................................................. 8-4

8.2.1 General .......................................................................................................................... 8-4 8.2.2 Wall Construction........................................................................................................... 8-7 8.2.3 Cost .........................................................................................................................8-12 8.2.4 Construction Inspection .................................................................................................8-12

8.3 SOLDIER PILE AND LAGGING WALLS................................................................................8-13 8.3.1 General .........................................................................................................................8-13 8.3.2 Wall Construction..........................................................................................................8-17 8.3.3 Cost .........................................................................................................................8-19 8.3.4 Construction Inspection .................................................................................................8-19

8.4 SLURRY WALLS .......................................................................................................................8-20 8.4.1 General .........................................................................................................................8-20 8.4.2 Slurry Wall Types..........................................................................................................8-23 8.4.3 Wall Construction..........................................................................................................8-26 8.4.4 Cost .........................................................................................................................8-34 8.4.5 Construction Inspection .................................................................................................8-34

8.5 TANGENT/SECANT PILE WALLS ..........................................................................................8-37 8.5.1 General .........................................................................................................................8-37 8.5.2 Wall Construction..........................................................................................................8-39 8.5.3 Cost .........................................................................................................................8-40 8.5.4 Construction Inspection .................................................................................................8-40

8.6 JET GROUTED WALLS ............................................................................................................8-42 8.6.1 General .........................................................................................................................8-42 8.6.2 Wall Construction..........................................................................................................8-45 8.6.3 Cost .........................................................................................................................8-54

FHWA NHI-07-071 vi June 2008 Earth Retaining Structures

8.6.4 Construction Inspection .................................................................................................8-54 8.7 DEEP MIXING METHOD (DMM) WALLS..............................................................................8-57

8.7.1 General .........................................................................................................................8-57 8.7.2 Wall Construction..........................................................................................................8-60 8.7.3 Cost .........................................................................................................................8-64 8.7.4 Construction Inspection .................................................................................................8-64

8.8 GROUND ANCHORS ................................................................................................................8-67 8.8.1 General .........................................................................................................................8-67 8.8.2 Wall Construction..........................................................................................................8-68 8.8.3 Load Testing of Ground Anchors ..................................................................................8-76 8.8.4 Cost .........................................................................................................................8-84 8.8.5 Construction Inspection .................................................................................................8-84

8.9 DESIGN OF FLEXIBLE NONGRAVITY CANTILEVERED WALLS....................................8-86 8.9.1 Sheet Pile and Soldier Pile and Lagging Walls..............................................................8-86 8.9.2 Design Steps for Flexible Nongravity Cantilevered Walls ............................................8-87

8.10 ANCHORED BULK HEAD (DEADMAN ANCHOR) WALLS ...............................................8-95 8.10.1 Overview .......................................................................................................................8-95 8.10.2 Free Earth Support.........................................................................................................8-96 8.10.3 Fixed Earth Support .......................................................................................................8-97 8.10.4 Deadman Anchor Systems...........................................................................................8-102

8.11 ANCHORED WALL DESIGN .................................................................................................8-102 8.11.1 Step 3: Select Corrosion Protection of Ground Anchors .............................................8-106 8.11.2 Step 4: Select Earth Pressure Diagram ........................................................................8-114 8.11.3 Step 5: Evaluate Factored Loads..................................................................................8-118 8.11.4 Step 6: Evaluate Individual Anchor Loads and Subgrade Reaction Force ..................8-118 8.11.5 Step 7: Evaluate Anchor Inclination ............................................................................8-122 8.11.6 Step 8: Select Tendon Type and Check Tensile Resistance.........................................8-122 8.11.7 Step 9: Evaluate Anchor Bond Length ........................................................................8-124 8.11.8 Step 10: Evaluate Factored Bending Moment and Flexural Resistance of Wall .........8-127 8.11.9 Step 11: Evaluate Bearing Resistance of Vertical Wall Element.................................8-131 8.11.10 Step 12: Evaluate Overall Stability of Anchored Wall at Service Limit State.............8-132 8.11.11 Step 13: Estimate Maximum Lateral Wall Movements and Settlements at the Service

Limit State .....................................................................................................8-135 8.12 DESIGN OF STIFF CANTILEVERED AND ANCHORED WALLS.....................................8-137

8.12.1 General .......................................................................................................................8-137 8.12.2 Soil-Structure Interaction analysis Methods ................................................................8-140 8.12.3 Slurry Walls .................................................................................................................8-151 8.12.4 Tangent and Secant Pile Walls ....................................................................................8-152 8.12.5 Jet Grouted Walls ........................................................................................................8-153 8.12.6 DMM Walls .................................................................................................................8-156

8.13 DRAINAGE SYSTEMS FOR CUT WALLS ...........................................................................8-160 CHAPTER 9 IN-SITU REINFORCED WALLS ............................................................................................ 9-1

9.1 INTRODUCTION ........................................................................................................................ 9-1 9.2 SOIL NAIL WALLS .................................................................................................................... 9-1

9.2.1 General .......................................................................................................................... 9-1

FHWA NHI-07-071 vii June 2008 Earth Retaining Structures

9.2.2 Feasibility of Soil Nails .................................................................................................. 9-3 9.2.3 Construction Materials and Methods .............................................................................9-13 9.2.4 Soil Nail Corrosion Protection.......................................................................................9-30 9.2.5 Cost .........................................................................................................................9-34 9.2.6 Design Concepts for Soil Nails......................................................................................9-35 9.2.7 Design of Soil Nail Walls ..............................................................................................9-72 9.2.8 Soil Nail Load Testing.................................................................................................9-101 9.2.9 Construction Inspection of Soil Nail Walls .................................................................9-106

9.3 MICROPILE WALLS ...............................................................................................................9-108 9.3.1 Introduction .................................................................................................................9-108 9.3.2 Construction Materials and Methods ...........................................................................9-109 9.3.3 Micropile Wall Design ................................................................................................9-112 9.3.4 Load Testing ................................................................................................................9-114 9.3.5 Construction Inspection ...............................................................................................9-115

CHAPTER 10 WALL SELECTION .................................................................................................................10-1

10.1 INTRODUCTION .......................................................................................................................10-1 10.2 STEP 1: IDENTIFY NEED FOR AN EARTH RETAINING SYSTEM ....................................10-1 10.3 STEP 2: IDENTIFY SITE CONSTRAINTS AND PROJECT REQUIREMENTS ....................10-2 10.4 STEP 3: EVALUATE PROJECT REQUIREMENTS AGAINST FACTORS AFFECTING

WALL SELECTION .....................................................................................................10-3 10.5 STEP 4: EVALUATE WALL ALTERNATIVES AGAINST WALL SELECTION FACTORS10-5

10.5.1 General .........................................................................................................................10-5 10.5.2 Selection Issues for Cut Wall Systems ..........................................................................10-5 10.5.3 Selection Issues for Fill Wall Systems...........................................................................10-6 10.5.4 Wall System Alternatives Evaluation ............................................................................10-6

10.6 STEP 5: SELECT AN ACCEPTABLE WALL TYPE..............................................................10-14 10.7 WALL SELECTION EXAMPLE..............................................................................................10-14 10.8 HYBRID WALL SYSTEMS.....................................................................................................10-19

10.8.1 General .......................................................................................................................10-19 10.8.2 Compatibility of Deformations....................................................................................10-19 10.8.3 Overall Stability of Hybrid Systems ............................................................................10-21 10.8.4 Example Hybrid Systems.............................................................................................10-23

CHAPTER 11 CONTRACTING APPROACHES...........................................................................................11-1

11.1 INTRODUCTION .......................................................................................................................11-1 11.2 METHOD CONTRACTING APPROACH.................................................................................11-2

11.2.1 Introduction ...................................................................................................................11-2 11.2.2 Contract Documents for Method Approach...................................................................11-3

11.3 PERFORMANCE CONTRACTING APPROACH ....................................................................11-8 11.3.1 Introduction ...................................................................................................................11-8 11.3.2 Implementing Performance Contracting Approach .......................................................11-8 11.3.3 Contract Documents for Performance Approach.........................................................11-10 11.3.4 Review and Approval ..................................................................................................11-12

11.4 CONTRACTOR DESIGN/BUILD APPROACH......................................................................11-12 11.5 RECOMMENDATIONS ...........................................................................................................11-13

FHWA NHI-07-071 viii June 2008 Earth Retaining Structures

11.6 SPECIFICATION RESOURCES ..............................................................................................11-14 CHAPTER 12 REFERENCES...........................................................................................................................12-1 APPENIDX STUDENT EXERCISES AND SOLUTIONS ..............................................................................A-1

Active Earth Pressure Calculation Lateral Load Distribution Due to Strip Load Sliding Resistance MSE Wall Design External Stability MSE Wall Internal Stability Corrosion Calculation Apparent Earth Pressure Diagrams Single-Tier Anchored Soldier Beam and Lagging Wall Design of a Two-Tier Anchored Soldier Pile and Lagging Wall Lateral Wall Movement Soil Nail Wall Design Fill Wall Selection Cut Wall Selection

FHWA NHI-07-071 ix June 2008 Earth Retaining Structures

LIST OF TABLES

Table 2-1 Summary of Information Needs and Testing Considerations for Fill and Cut Wall Applications ....... 2-3 Table 2-2 Sources of Historical Site Data ............................................................................................................ 2-5 Table 2-3 In-Situ Testing Methods Used in Soil .................................................................................................. 2-8 Table 2-4 Sampling Guidelines (after WFLHD, 2004) .......................................................................................2-12 Table 2-5 Typical Properties of Compacted Soils (after NAVFAC, 1986).........................................................2-27 Table 2-6 Unconfined Compressive Strength of Particles for Rockfill Grades in Figure 2-4 .............................2-28 Table 2-7 Range of Dry Densities for Lightweight Fills (after Elias et al., 2006)...............................................2-35 Table 2-8 Correlation between N and g of Granular Soils (after Bowles, 1988).................................................2-38 Table 2-9 Correlation between N and g of Cohesive Soils (after Bowles, 1988) ................................................2-38 Table 2-10 Relationship between SPT N Value and Internal Friction angle of Granular Soils (after AASHTO

LRFD, 2007) .......................................................................................................................................2-45 Table 2-11 Summary of Correlations for Cc (after Holtz and Kovacs, 1981) .......................................................2-48 Table 2-12 Casagrande Method to Evaluate p ....................................................................................................2-50 Table 2-13 Description of Geological Mapping Terms.........................................................................................2-59 Table 2-14 Rock Material Strengths......................................................................................................................2-60 Table 2-15 Weathering Grades..............................................................................................................................2-60 Table 2-16 Rock Quality Description Based on Rqd ............................................................................................2-61 Table 2-17 Csir Classification of Jointed Rock Mass............................................................................................2-64 Table 2-18 Typical Ranges of Friction angles for a Variety of Rock Types .........................................................2-71 Table 2-19 Permeability of Typical Rocks and Soils (after Wyllie and Mah, 1998).............................................2-79 Table 3-1 Typical Values for Equivalent Fluid Unit Weight of Soils (after AASHTO, 2007) ...........................3-12 Table 3-2 Wall Friction and Adhesion for Dissimilar Materials (after NAVFAC, 1986) ...................................3-22 Table 3-3 Lateral Earth and Hydrostatic Pressures at Various Depths for Example 1 ........................................3-50 Table 3-4 Computation of Lateral Earth Pressures Due to Line Load.................................................................3-54 Table 4-1 Load Combinations and Load Factors (AASHTO, 2007).................................................................... 4-5 Table 4-2 Load Factors for Permanent Loads, P (modified after AASHTO, 2007) ............................................ 4-6 Table 4-3 Values of Resistance Factors Corresponding to Different Values of Factor of Safety and Dead to Live Load Ratios for DC = 1.25 and LL = 1.75 ................................................................................... 4-8 Table 5-1 Design Steps for Gravity and Semi-Gravity Walls .............................................................................5-11 Table 5-2 Suggested Gradation for Backfill for Cantilever Semi-Gravity and Gravity Retaining Walls............5-12 Table 5-3 Inspector Responsibilities for a Typical CIP Gravity and Semi Gravity Wall Project........................5-30 Table 6-1 Typical Height-Thickness Relationship for Bin Walls (after Contech) ..............................................6-18 Table 6-2 Inspector Responsibilities for a Typical Modular Gravity Wall Project .............................................6-34 Table 7-1 Summary of Reinforcement and Face Panel Details for Selected MSE Wall Systems (after Elias et al., 2004)........................................................................................................................................... 7-3 Table 7-2 Recommended Limits of Electrochemical Properties for Select Backfills When Using Steel

Reinforcement .....................................................................................................................................7-10 Table 7-3 Recommended Limits of Electrochemical Properties for Select Backfills When Using Geosynthetic Reinforcements .............................................................................................................7-11 Table 7-4 MSE Wall Field Inspection Checklist .................................................................................................7-30

FHWA NHI-07-071 x June 2008 Earth Retaining Structures

Table 7-5 Design Steps for MSE Walls...............................................................................................................7-34 Table 7-6 Minimum Embedment Requirements for MSE Walls (after AASHTO, 2007)...................................7-36 Table 7-7 Typical Values for a (after AASHTO, 2007) ......................................................................................7-58 Table 7-8 Resistance Factors for Tensile Resistance (after AASHTO, 2007).....................................................7-62 Table 7-9 Installation Damage Reduction Factors (after Elias, 2000).................................................................7-67 Table 7-10 Creep Reduction Factors (RFCR) .......................................................................................................7-67 Table 7-11 Aging Reduction Factors (RFD) for PET............................................................................................7-68 Table 7-12 Relationship between Joint Width and Limiting Differential Settlements for MSE Precast Panels (after Elias et al., 2001) .......................................................................................................................7-71 Table 7-13 Equivalent Height of Soil for Vehicular Loading (after AASHTO, 2007) .........................................7-79 Table 7-14 Summary of Unfactored Vertical Loads and Moment Arms for Design Example..............................7-80 Table 7-15 Summary of Unfactored Horizontal Loads and Moment Arms for Design Example .........................7-80 Table 7-16 Load Factors and Load Combinations.................................................................................................7-80 Table 7-17 Factored Vertical Loads and Moments ...............................................................................................7-81 Table 7-18 Factored Horizontal Loads and Moments ...........................................................................................7-81 Table 7-19 Summary for Eccentricity Check ........................................................................................................7-81 Table 7-20 Summary for Checking Bearing Resistance........................................................................................7-84 Table 8-1 Inspector Responsibilities for a Typical Sheet Pile Wall Project ........................................................8-12 Table 8-2 Inspector Responsibilities for a Typical Soldier Pile and Lagging Wall Project ................................8-19 Table 8-3 Inspector Responsibilities for a Typical Slurry Wall Project ..............................................................8-35 Table 8-4 Inspector Responsibilities for a Typical Tangent/Secant Pile Wall Project ........................................8-41 Table 8-5 Inspector Responsibilities for a Typical Jet-Grouted Wall Project .....................................................8-56 Table 8-6 Inspector Responsibilities for Typical DMM Walls............................................................................8-65 Table 8-7 Example of QA/QC Testing Program for DMM Walls ......................................................................8-66 Table 8-8 Load Schedule and Observation Periods for Extended Creep Test for Permanent Anchor ................8-79 Table 8-9 Inspector Responsibilities for Ground Anchors and Anchored Walls.................................................8-85 Table 8-10 Design Steps for Flexible Nongravity Cantilevered Walls..................................................................8-88 Table 8-11 Recommended Thickness of Wood Lagging (after Goldberg et al., 1976).........................................8-94 Table 8-12 Bending Moments for Facing Design (AASHTO, 2007)....................................................................8-95 Table 8-13 Design Steps for Anchored Walls .....................................................................................................8-105 Table 8-14 Criteria for Electrochemical Properties of Soils for Ground Anchor Applications (after Cheney, 1988)..........................................................................................................................8-113 Table 8-15 Properties of Prestressing Steel Bars (ASTM A722) ........................................................................8-123 Table 8-16 Properties of 0.6 in. Diameter Prestressing Steel Strands (ASTM A416, Grade 270) ......................8-123 Table 8-17 Guidance Relationship between Tendon Size and Trumpet Opening Size (after Sabatini et al., 1999) ................................................................................................................8-124 Table 8-18 Presumptive (Nominal) Bond Stress for Ground/Grout Interface Along Anchor Bond Zone (after PTI, 1996)................................................................................................................................8-128 Table 8-19 Cutoff Functions and Watertightness of Excavation Walls (after ASCE, 1997)...............................8-148 Table 8-20 Summary of System Variables and their Impact on Basic Design Elements ....................................8-154 Table 8-21 Typical Range of Jet Grouting Parameters and Jet-Grouted Soil Properties (adapted from Kauschinger and Welsh, 1989) ..................................................................................8-155 Table 8-22 Range of Typical Soilcrete Strengths (Three Fluid System) (after Elias et al., 2006) ......................8-156 Table 8-23 Typical Improved Engineering Characteristics of Soils Treated with DMM (Wet Mix) (after Elias et al., 2006) .....................................................................................................................8-157

FHWA NHI-07-071 xi June 2008 Earth Retaining Structures

Table 9-1 Criteria for Assessing Ground Corrosion Potential.............................................................................9-31 Table 9-2 Recommendations for Minimum Levels of Corrosion Protection for Soil Nails ................................9-33 Table 9-3 Estimated Ultimate Bond Strength of Soil Nails in Soil and Rock (after Elias and Juran, 1991) .......9-47 Table 9-4 Factors CF (after Lazarte, 2003) ..........................................................................................................9-56 Table 9-5 Values of (h/H)i and C As Functions of Soil Conditions ...................................................................9-68 Table 9-6 Design Steps for Soil Nail Walls.........................................................................................................9-72 Table 9-7 Minimum Recommended Factors of Safety for the Design of Soil Nail Walls Using the ASD Method (after Lazarte, 2003) ..............................................................................................................9-73 Table 9-8 Variable Parameters Used in Design Charts (Lazarte et al., 2003) .....................................................9-87 Table 9-9 Threaded Bar Properties......................................................................................................................9-90 Table 9-10 Welded Wire Mesh Dimensions (after WRI, 2001) ............................................................................9-94 Table 9-11 Headed-Stud Dimensions (Metric and English Units) (after Byrne et al., 1996) ................................9-96 Table 9-12 Facing Resistance for Various Failure Modes (after Lazarte et al., 2003) ..........................................9-98 Table 9-13 Soil Nail Load Test Types.................................................................................................................9-102 Table 9-14 Inspector Responsibilities for a Typical Soil Nail Wall ....................................................................9-106 Table 9-15 Inspector Responsibilities for a Typical Micropile Wall Project ......................................................9-115 Table 10-1 Wall Selection Factors ........................................................................................................................10-4 Table 10-2 Summary of Evaluation Factors for Cut Walls (after Sabatini et al., 1997)........................................10-7 Table 10-3 Summary of Evaluation Factors for Fill Walls (after Sabatini et al., 1997) ........................................10-8 Table 10-4 Summary of Cut Wall Costs..............................................................................................................10-15 Table 10-5 Summary of Fill Wall Costs..............................................................................................................10-15 Table 10-6 Initial Rating of Each Wall Selection Factor for Each Wall Alternative...........................................10-18 Table 10-7 Wall Selection Matrix and Total Score of Each Wall Alternative ....................................................10-20

Table 11-1 Identified Sources for Wall Specifications........................................................................................11-15

FHWA NHI-07-071 xii June 2008 Earth Retaining Structures

FHWA NHI-07-071 xiii June 2008 Earth Retaining Structures

LIST OF FIGURES

Figure 1-1 Schematic of a Retaining Wall and Common Terminology .............................................................. 1-1 Figure 1-2 Variety of Retaining Walls (after ORourke and Jones, 1990) .......................................................... 1-3 Figure 1-3 Classification of Earth Retaining Systems (after ORourke and Jones, 1990)................................... 1-6 Figure 2-1 Boring Layout for Anchored Wall ..................................................................................................... 2-6 Figure 2-2 Drained Stress-Strain Behavior.........................................................................................................2-16 Figure 2-3 Mohr-Coulomb Failure Criteria........................................................................................................2-16 Figure 2-4 Typical Ranges of Friction angle for Rockfills, Gravels, and Sands (after Terzaghi et al., 1996)....2-28 Figure 2-5 Correlation between Drained Friction angle and the Dry Unit Weight, Relative Density, and Soil

Classification (after NAVFAC, 1986) ..............................................................................................2-29 Figure 2-6 Example Shear Strength Property Evaluation for Clayey Backfill ...................................................2-30 Figure 2-7 Classification Chart for Swelling Potential (after Seed et al., 1962) ................................................2-36 Figure 2-8 Test Data from Triaxial Compression Test with Pore Pressure Measurements ................................2-40 Figure 2-9 Plasticity Based VST Correction Factors..........................................................................................2-41 Figure 2-10 Relationship between and PI (after Terzaghi et al., 1996) ...........................................................2-43 Figure 2-11 Residual Friction angles for Clayey Soils (after Stark and Eid, 1994) .............................................2-43 Figure 2-12 Friction Angle of Cohesionless Soils (a) from Uncorrected SPT N Values (modified after Peck,

Hanson, and Thornburn 1974) and (b) As a Function of Normalized Overburden (modified after Schmertmann, 1975).........................................................................................................................2-45

Figure 2-13 Correlation of with Normalized CPT qt Data in Clean Sands ......................................................2-46 Figure 2-14 Definition of Cc, Cr, Cs, and p (Sabatini et al., 2002) ...................................................................2-47 Figure 2-15 Illustration of Casagrande Method to Evaluate Preconsolidation Stress...........................................2-50 Figure 2-16 Evaluation of C ...............................................................................................................................2-53 Figure 2-17 Range of Hydraulic Conductivity Values Based on Soil Type (after Holtz and Kovacs, 1981).......2-55 Figure 2-18 Range of Hydraulic Conductivity Based on Grain Size (after Geosyntec, 1991) .............................2-56 Figure 2-19 Illustration of Geological Mapping Terms (after Wyllie, 1999, Foundations on Rock, Figure 4.4b, p. 101, E&Fn Spon) ..........................................................................................................................2-57 Figure 2-20 List of Parameters and Categories Describing Rock Mass Characteristics (after Wyllie, 1999) ......2-58 Figure 2-21 Calculation of Core Recovery and ROD...........................................................................................2-62 Figure 2-22 General Chart for GSI Estimates from Geological Observations (after Marinos et al., 2004)..........2-67 Figure 2-23 GSI Estimates for Heterogeneous Rock Masses (after Marinos et al., 2004) ...................................2-68 Figure 2-24 Point Load Strength Test Equipment ................................................................................................2-70 Figure 2-25 Definition of Joint Roughness Coefficient, JRC (after Barton, 1973) ..............................................2-74 Figure 2-26 Simplified Division of Filled Discontinuities into Displaced, and Normally Consolidated and

Overconsolidated Categories (after Wyllie, 1999)............................................................................2-75 Figure 2-27 RocLab Window to Select Uniaxial Compressive Strength of Intact Rock......................................2-76 Figure 2-28 RocLab Window to Select GSI.........................................................................................................2-77 Figure 2-29 RocLab Window to Select mi Value.................................................................................................2-78 Figure 2-30 Shear Strength Parameters for Weathered Shale Using RocLab Software .......................................2-79 Figure 2-31 Influence of Joint Openings and Joint Spacing on the Permeability of Rocks (after Hoek and Bray, 1977) .............................................................................................................2-80 Figure 3-1 Magnitudes and Patterns of Movement to Develop Lateral Earth Pressures (after Sabatini et al., 1997)................................................................................................................. 3-3 Figure 3-2 Mobilization of Rankine Active and Passive Horizontal Pressures for a Smooth Retaining Wall .... 3-4

FHWA NHI-07-071 xiv June 2008 Earth Retaining Structures

Figure 3-3 Limiting Active and Passive Horizontal Pressures ............................................................................ 3-4 Figure 3-4 (a) Wall Pressures for a Cohesionless Soil; and (b) Wall Pressures for Soil with a Cohesion Intercept (after Padfield and Mair, 1984)........................................................................................... 3-7 Figure 3-5 Coulomb Coefficients Ka and Kp for Sloping Wall with Wall Friction and Sloping Backfill (after NAVFAC, 1986) ...................................................................................................................... 3-9 Figure 3-6 Wall Friction on Soil Wedges (after Padfield and Mair, 1984) ........................................................3-10 Figure 3-7 Comparison of Plane and Curved (Log-Spiral) Failure Surfaces (a) Active Case and (b) Passive Case (after Sokolovski, 1954) ........................................................................................3-12 Figure 3-8 Earth Pressure Immediately after Loading (after Padfield and Mair, 1984) .....................................3-15 Figure 3-9 Effect of Wall Movement on Wall Pressures (after Canadian Foundation Engineering Manual, 1992)...................................................................................................................................3-19 Figure 3-10 Simplified Drained Stress-Displacement Relationship for a Stiff Clay (modified after Padfield and Mair, 1984) ..................................................................................................................3-20 Figure 3-11 Passive Coefficients for Sloping Wall with Wall Friction and Horizontal Backfill (Caquot and

Kerisel, 1948; NAVFAC, 1986) .......................................................................................................3-25 Figure 3-12 Passive Coefficients for Vertical Wall with Wall Friction and Sloping Backfill (Caquot and Kerisel, 1948; NAVFAC, 1986) .......................................................................................................3-26 Figure 3-13 Pressure Distribution for Stratified Soils ..........................................................................................3-27 Figure 3-14 Cross Section of Model Wall (modified after Mueller et al., 1998) .................................................3-28 Figure 3-15 Lateral Wall Movements and Earth Pressures with Excavation at First Anchor Level (Cantilever

Stage) (modified after Mueller et al., 1998)......................................................................................3-29 Figure 3-16 Lateral Wall Movements and Earth Pressures During Anchor Stressing (modified after Mueller et al., 1998)..........................................................................................................................3-30 Figure 3-17 Lateral Wall Movements and Earth Pressures with Excavation at Lower Anchor Level (modified after Mueller et al., 1998).................................................................................................3-31 Figure 3-18 Lateral Wall Movements and Earth Pressures with Excavation at Design Grade (modified after Mueller et al., 1998).................................................................................................3-31 Figure 3-19 Apparent Earth Pressure Diagram for Anchored Wall in Sand ........................................................3-33 Figure 3-20 Computation of Lateral Pressures for Static Groundwater Case.......................................................3-33 Figure 3-21 Flow Net for a Retaining Wall (after Padfield and Mair, 1984) .......................................................3-34 Figure 3-22 Gross and Net Water Pressures Across a Retaining Wall (modified after Padfield and Mair, 1984) ..................................................................................................................3-35 Figure 3-23 (a) Retaining Wall with Uniform Surcharge Load and (b) Retaining Wall with Line Loads (see Railway Tracks) and Point Loads (see Catenary Structure) ......................................................3-38 Figure 3-24 Lateral Pressure Due to Surcharge Loadings (after USS Steel Sheet-Pile Manual, 1975)................3-39 Figure 3-25 Typical Residual Earth Pressure after Compaction of Backfill Behind an Unyielding Wall (after Clough and Duncan, 1991)......................................................................................................3-40 Figure 3-26 Estimation of Silo Pressures..........................................................................................................3-42 Figure 3-27 Seismic Forces Behind a Gravity Wall .............................................................................................3-43 Figure 3-28 Effects of Seismic Coefficients and Friction angle on Seismic Active Pressure Coefficient (after Lam and Martin, 1986)............................................................................................................3-45 Figure 3-29 Example Problem 1 Geometry and Soil Conditions .........................................................................3-50 Figure 3-30 (a) Lateral Effective Earth Pressure Diagram and (b) Water Pressure Diagram...............................3-51 Figure 3-31 Pressure Diagrams for Example Problem 2 ......................................................................................3-52 Figure 3-32 Geometry of Example Problem 3 .....................................................................................................3-52 Figure 3-33 Lateral Pressure with Depth Due to Line Load.................................................................................3-54 Figure 4-1 Equations Used to Relate LRFD Resistance Factor to ASD FS (after Samtani, 2007) ..................... 4-6

FHWA NHI-07-071 xv June 2008 Earth Retaining Structures

Figure 5-1 Cast-in-Place Gravity Wall ................................................................................................................ 5-2 Figure 5-2 Cast-in-Place (CIP) Concrete Retaining Walls and Terminology (a) Cantilever Wall (Bowles, 1988); (b) Counterfort Wall; and (c) Buttress Wall (Teng, 1962) ..................................................... 5-3 Figure 5-3 Common Proportions of Cantilever Walls (after Teng, 1962)........................................................... 5-4 Figure 5-4 CIP Cantilever Retaining Wall .......................................................................................................... 5-4 Figure 5-5 Common Proportions of Counterfort Walls (after Teng, 1962)......................................................... 5-5 Figure 5-6 CIP Counterfort Wall Construction in a Cut Application .................................................................. 5-6 Figure 5-7 Other Types of Cast-in-Place (CIP) Walls: (a) Fill Wall with Limited Row, (b) Cut Wall with Limited Row, and (c) U-Wall for Depressed Roadway..................................................................... 5-7 Figure 5-8 CIP U-Wall for Depressed Roadway................................................................................................. 5-8 Figure 5-9 Strength Limit States for Rigid Gravity and Semi-Gravity Walls ....................................................5-10 Figure 5-10 CIP Abutment with Integral Wingwalls............................................................................................5-13 Figure 5-11 Typical Application of Load Factors for Eccentricity and Sliding ...................................................5-14 Figure 5-12 Typical Application of Load Factors for Bearing Resistance ...........................................................5-14 Figure 5-13 Example CIP Wall with Traffic Barrier ............................................................................................5-16 Figure 5-14 Computation of Barrier Load at Footing Level.................................................................................5-16 Figure 5-15 Loading and Eccentricity for Walls Founded on Soil .......................................................................5-18 Figure 5-16 Loading and Eccentricity for Walls Founded on Rock.....................................................................5-19 Figure 5-17 Typical Modes of Global Stability (after Bowles, 1988) ..................................................................5-22 Figure 5-18 Typical Movement of Pile Supported Cast-in-Place (CIP) Wall with Soft Foundation ...................5-23 Figure 5-19 Potential Sources of Subsurface Water.............................................................................................5-25 Figure 5-20 Typical Retaining Wall Drainage Alternatives (after Sabatini et al., 1997) .....................................5-25 Figure 5-21 Inclined Drain for Reducing Water Pressure Behind Wall (after Cedergren, 1989).........................5-26 Figure 5-22 Drains Behind Backfill in Cantilever Wall in a Cut Situation ..........................................................5-27 Figure 6-1 Modular Gravity Walls (a) Metal Bin Wall; (b) Precast Concrete Crib Wall; (c) Precast Concrete

Module Wall; and (d) Gabion Wall (after AASHTO, 2007) ............................................................. 6-1 Figure 6-2 Examples of Modular Gravity Wall Applications (after Contech, 1997) .......................................... 6-3 Figure 6-3 Crib Walls (a) Uniform Cross-Section; (b) Stepped Cross-Section; and (c) Typical Details of a

Reinforced Concrete Crib Wall (after HKGEO, 1993)...................................................................... 6-5 Figure 6-4 Setting Precast Elements for an Open Faced Crib Wall..................................................................... 6-6 Figure 6-5 Concrete Module Wall (a) Typical Section; (b) Typical Module; and (c) Precast Parapet (after

Doublewal Corporation) .................................................................................................................... 6-9 Figure 6-6 Construction of Concrete Module Wall (a) Placement of Precast Modules; (b) Placing Fill Within the Modules; and (c) Compacting the Infill Material (after Doublewal Corp.) ................................6-10 Figure 6-7 Gabion Baskets (a) Module Without Diaphragms and (b) Module with Diaphragms......................6-13 Figure 6-8 Gabion Wall Construction (a) Filling Gabion Baskets with Stone and (b) Closing Gabion Lid for Tying ...........................................................................................................................................6-15 Figure 6-9 Typical Geometry of Type 2 Bin Wall (a) Plan, (b) Elevation and (c) Section a-a (after Contech) ..................................................................................................................................6-19 Figure 6-10 Elements of Bin Walls (a) T-Shaped Vertical Connector for Bin Wall Type 2 and (b) Channel Shaped Vertical Connector for Bin Wall Type 1(after Contech) ..................................6-20 Figure 6-11a Construction of a Bin Wall (a) Setting Preassembled Panels and (b) Filling the Completed Bins (after Contech) ..................................................................................................................................6-21 Figure 6-11b Construction of a Bin Wall (a) Setting Preassembled Panels and (b) Filling the Completed Bins (after Contech) ..................................................................................................................................6-21 Figure 6-12 Construction of Bin Walls at Curves (a) Typical Outside Corner; and (b) Typical Inside Corner (after Contech) ..................................................................................................................................6-22

FHWA NHI-07-071 xvi June 2008 Earth Retaining Structures

Figure 6-13 Bin Wall with (a) Corrugated Steel Face Panels; and (b) Precast Concrete Face Panels (after Contech) ..................................................................................................................................6-24 Figure 6-14 Earth Pressure Distribution for Modular Walls with Continuous Pressure Surfaces (Figure 3.11.5.9-1 from AASHTO, 2007) ........................................................................................6-26 Figure 6-15 Earth Pressure Distribution for Modular Walls with Irregular Pressure Surfaces (Figure 3.11.5.9-2 from AASHTO, 2007) ........................................................................................6-27 Figure 6-16 Load Distribution for Modular Wall with Footings..........................................................................6-28 Figure 6-17 Geometry and Parameters of Example Problem ...............................................................................6-31 Figure 6-18 Vertically Installed T-Wall Units (after The Neel Company, 2004).................................................6-36 Figure 6-19 Battered T-Wall Units (after The Neel Company, 2004)..................................................................6-37 Figure 7-1 Principal Components of a Mechanically Stabilized Earth Wall (after Christopher, et al., 1990)..... 7-2 Figure 7-2 Examples of MSE Wall Applications (a) Retaining Wall; (b) Access Ramp; (c) Waterfront Structure; and (d) Bridge Abutment .................................................................................................. 7-6 Figure 7-3 Examples of MSE Walls.................................................................................................................... 7-7 Figure 7-4 Metallic Reinforcements (a) Ribbed Metal Strip and (b) Welded Bar Mat ......................................7-13 Figure 7-5 Geosynthetic Reinforcements (a) Geogrid and (b) Geotextile Facing ..............................................7-14 Figure 7-6 Various Types of Wall Facing (after Wu, 1994)...............................................................................7-17 Figure 7-7 MSE Wall Surface Textures .............................................................................................................7-18 Figure 7-8 Examples of Commercially Available MBW Units (after Simac Et Al, 1996) ................................7-20 Figure 7-9 Construction of MSE Wall with Inextensible Strip Reinforcements: (a) Concrete Leveling Pad

Construction, (b) Erection of Facing Elements, (c) Placement of Reinforcements (d) Placement of Backfill, (e) Spreading of Backfill, and (f) Backfill Compaction.................................................7-23 Figure 7-10 Construction Procedures of Geotextile Retained Earth Wall with Wrap-Around Facing.................7-24 Figure 7-11 Geotextile Retained Earth Wall Details ............................................................................................7-24 Figure 7-12 Lightweight Compaction Adjacent to Wall Facing ..........................................................................7-28 Figure 7-13 Potential External Failure Mechanisms for MSE Walls ...................................................................7-33 Figure 7-14 Pressure Diagram for MSE Walls with Horizontal Backslope and Traffic Surcharge (after AASHTO, 2007) .....................................................................................................................7-37 Figure 7-15 Typical Application of Live Load Surcharge for MSE Walls (after AASHTO, 2007).....................7-38 Figure 7-16 Distribution of Stress from Concentrated Vertical Load (after AASHTO, 2007).............................7-39 Figure 7-17 Distribution of Stress from Concentrated Horizontal Loads for External and Internal Stability

Calculations (after AASHTO, 2007) ................................................................................................7-40 Figure 7-18 Pressure Diagram for MSE Walls with Sloping Backslope (after AASHTO, 2007) ........................7-42 Figure 7-19 Pressure Diagram for MSE Walls with Broken Backslope (after AASHTO, 2007).........................7-42 Figure 7-20 Calculation of Eccentricity for Horizontal Backslope with Traffic Surcharge Condition (after Elias and Christopher 1996)....................................................................................................7-44 Figure 7-21 Calculation of Eccentricity for Sloping Backslope Condition (after Elias and Christopher 1996)...7-45 Figure 7-22 Mechanisms of Internal Failure in MSE Walls (a) Tension Failure and (b) Pullout Failure (after Christopher et al., 1990)..........................................................................................................7-49 Figure 7-23 Location of Potential Failure Surface for Internal Stability Design of MSE Walls (a) Inextensible

Reinforcements and (b) Extensible Reinforcements (after Elias et al., 2001) ..................................7-50 Figure 7-24 Variation of the Coefficient of Lateral Stress Ratio (K/Ka) with Depth in a Mechanically Stabilized Earth Wall (after AASHTO, 2007) ..................................................................................7-52 Figure 7-25 Definitions of B, Sh, and Sv for (a) Metal and (b) Geosynthetic Reinforcements (after AASHTO, 2007) .....................................................................................................................7-55 Figure 7-26 Mechanisms of Pullout Resistance. (a) by Friction, (b) by Passive Resistance (after Christopher et al., 1990 and Lawson, 1992)............................................................................7-56

FHWA NHI-07-071 xvii June 2008 Earth Retaining Structures

Figure 7-27 Typical Values for F* (after AASHTO, 2007) .................................................................................7-61 Figure 7-28 Cross Section Area for Strips............................................................................................................7-64 Figure 7-29 Cross Section Area for Bars..............................................................................................................7-64 Figure 7-30 Drain Immediately Behind Concrete Facing in MSE Wall...............................................................7-73 Figure 7-31 Drain Behind the Backfill in a Wall, in a Backcut, and Fill Situation ..............................................7-73 Figure 7-32 Impervious Geomembrane Details ...................................................................................................7-74 Figure 7-33 (a) Geometry of the Problem and (b) External Forces to Be Considered in analysis........................7-77 Figure 7-34 Wall Face Panels and Spacing between Reinforcements..................................................................7-78 Figure 8-1 Primary Types of Externally Supported Structural Walls: (a) Soldier Pile and Lagging Wall; (b)

Soldier Pile and Cast-in-Place Concrete Lagging Wall; (c) Master Pile Wall; (d) Sheet Pile Wall; (e) Slurry (Diaphragm) Wall; (f) Secant Pile Wall; (g) Tangent Pile Wall; and (h) Interlocking H-Pile Wall (after Dismuke, 1991) .......................................................................... 8-2 Figure 8-2 Wall Support Systems: (a) Cantilever Wall; (b) Earth Berm Support; (c) Raker System; (d) Deadman Anchor; (e) Cross-Lot Braced Wall; and (f) Anchored Wall (after NAVFAC,