TABLE OF CONTENTS (Continued)2.4APPLICATIONSOFGROUNDANCHORS162.4.1 Highway Retaining Walls.162.4.2Slope and Landslide Stabilization..172.4.3TiedownStructuresCHAPTER3SITEINVESTIGATIONANDTESTING..193.1 INTRODUCTION...193.2FIELDRECONNAISSANCE.193.3SUBSURFACEINVESTIGATION..203.3.1General..203.3.2Soil and Rock Stratigraphy.213.3.3.22Groundwater3.4LABORATORYSOILANDROCKTESTING223.4.1.22General3.4.2.23Classification and Index Properties3.4.3.23Shear Strength..233.4.4Consolidation.3.4.5 Electrochemical Criteria..243.5INSITUSOILANDROCKTESTING.24CHAPTER4BASICPRINCIPLESOFANCHOREDSYSTEMDESIGN..264.1GENERALDESIGNCONCEPTSFORANCHOREDWALLS.264.2FAILUREMECHANISMSOFANCHOREDSYSTEMS...284.2.1..28General4.2.2FailureMechanismsof theGroundAnchor284.2.3Failure of Soldier Beams.314.2.4.Failure ofLagging.324.3SELECTIONOFSOILSHEARSTRENGTHPARAMETERSFORDESIGN.......334.3.1General.334.3.2Drained Shear Strength of Granular Soils..334.3.3Undrained Shear Strengthof Normally Consolidated Clay.33iv
TABLE OF CONTENTS (Continued) iv 2.4 APPLICATIONS OF GROUND ANCHORS.16 2.4.1 Highway Retaining Walls.16 2.4.2 Slope and Landslide Stabilization.17 2.4.3 Tiedown Structures.17 CHAPTER 3 SITE INVESTIGATION AND TESTING.19 3.1 INTRODUCTION .19 3.2 FIELD RECONNAISSANCE.19 3.3 SUBSURFACE INVESTIGATION.20 3.3.1 General.20 3.3.2 Soil and Rock Stratigraphy.21 3.3.3 Groundwater.22 3.4 LABORATORY SOIL AND ROCK TESTING.22 3.4.1 General.22 3.4.2 Classification and Index Properties.23 3.4.3 Shear Strength.23 3.4.4 Consolidation.23 3.4.5 Electrochemical Criteria.24 3.5 IN SITU SOIL AND ROCK TESTING.24 CHAPTER 4 BASIC PRINCIPLES OF ANCHORED SYSTEM DESIGN .26 4.1 GENERAL DESIGN CONCEPTS FOR ANCHORED WALLS .26 4.2 FAILURE MECHANISMS OF ANCHORED SYSTEMS.28 4.2.1 General.28 4.2.2 Failure Mechanisms of the Ground Anchor.28 4.2.3 Failure of Soldier Beams .31 4.2.4. Failure of Lagging.32 4.3 SELECTION OF SOIL SHEAR STRENGTH PARAMETERS FOR DESIGN .33 4.3.1 General.33 4.3.2 Drained Shear Strength of Granular Soils.33 4.3.3 Undrained Shear Strength of Normally Consolidated Clay.33
TABLE OF CONTENTS (Continued).344.3.4UndrainedShearStrengthofOverconsolidatedClay4.3.5Drained ShearStrengthofOverconsolidated Clay...344.4EARTHPRESSURES..364.4.1General.364.4.2ActiveandPassiveEarthPressure..364.4.3Earth Pressure at Rest.414.4.4InfluenceofMovement onEarthPressure41CHAPTER5DESIGNOFANCHOREDSYSTEMS.465.1INTRODUCTION.465.2EVALUATIONOFEARTHPRESSURESFORWALLDESIGN....475.2.1Introduction475.2.2Background.48.495.2.3Terzaghiand PeckApparentEarthPressureDiagrams5.2.4RecommendedApparent EarthPressureDiagramfor Sands..505.2.5Recommended Apparent Earth Pressure Diagram for Stiff to Hard Fissured.52Clays5.2.6Recommended Apparent EarthPressureDiagramforSoft toMediumClays575.2.7...60Loading Diagrams for Stratified Soil Profiles..605.2.8Sliding Wedge Analysis Method.5.2.9.62WaterPressures5.2.10 Earth Pressures Due To Surface Loads.645.2.10.1..64Uniform Surcharge Loads..645.2.10.2PointLoads,LineLoads.andStripLoads.5.3GROUNDANCHORDESIGN.655.3.1..65Introduction5.3.2 Location of Critical Potential Failure Surface..655.3.3Calculation of Ground Anchor Loads from Apparent Earth Pressure Diagrams ......655.3.4DesignoftheUnbonded Length..675.3.5..68CompressionAnchors.5.3.6Design of the Anchor Bond Length.69V
TABLE OF CONTENTS (Continued) v 4.3.4 Undrained Shear Strength of Overconsolidated Clay.34 4.3.5 Drained Shear Strength of Overconsolidated Clay.34 4.4 EARTH PRESSURES .36 4.4.1 General.36 4.4.2 Active and Passive Earth Pressure.36 4.4.3 Earth Pressure at Rest.41 4.4.4 Influence of Movement on Earth Pressure.41 CHAPTER 5 DESIGN OF ANCHORED SYSTEMS.46 5.1 INTRODUCTION .46 5.2 EVALUATION OF EARTH PRESSURES FOR WALL DESIGN.47 5.2.1 Introduction.47 5.2.2 Background .48 5.2.3 Terzaghi and Peck Apparent Earth Pressure Diagrams.49 5.2.4 Recommended Apparent Earth Pressure Diagram for Sands.50 5.2.5 Recommended Apparent Earth Pressure Diagram for Stiff to Hard Fissured Clays.52 5.2.6 Recommended Apparent Earth Pressure Diagram for Soft to Medium Clays .57 5.2.7 Loading Diagrams for Stratified Soil Profiles.60 5.2.8 Sliding Wedge Analysis Method.60 5.2.9 Water Pressures.62 5.2.10 Earth Pressures Due To Surface Loads.64 5.2.10.1 Uniform Surcharge Loads.64 5.2.10.2 Point Loads, Line Loads, and Strip Loads.64 5.3 GROUND ANCHOR DESIGN .65 5.3.1 Introduction.65 5.3.2 Location of Critical Potential Failure Surface.65 5.3.3 Calculation of Ground Anchor Loads from Apparent Earth Pressure Diagrams.65 5.3.4 Design of the Unbonded Length.67 5.3.5 Compression Anchors.68 5.3.6 Design of the Anchor Bond Length.69
TABLE OFCONTENTS (Continued)5.3.7SpacingRequirements forGroundAnchors.75..775.3.8Selection of Prestressing Steel Element5.4WALLDESIGNBASEDONLATERALPRESSURES.785.4.1 Design of Soldier Beams and Sheet-Piles.78..815.4.2Design of Lagging for Temporary Support..835.4.3Design of Wales and Permanent Facing5.5LATERALCAPACITYOFEMBEDDEDPORTIONOFWALL.845.5.1.84General.5.5.2EvaluationofUltimatePassiveResistance...845.5.2.1Soldier Beam and Lagging Walls.845.5.2.2ContinuousWalls.865.5.3Depthof PenetrationbelowExcavation....86..875.5.4ComparisonofWang-ReeseandBromsMethodforCompetent Soils.5.6AXIALCAPACITYOFWALI..885.6.1..88Introduction5.6.2..89Axial Load Evaluation5.6.3Axial Capacity Design of Driven Soldier Beams.905.6.3.1General...905.6.3.2..90Effective Stress Analysis for Driven Soldier Beams.5.6.3.3Total Stress Analysis forDriven Soldier Beams in Clays..92.935.6.4Axial Capacity Design Of Drilled-in Soldier Beams5.6.4.1General...935.6.4.2..93Cohesionless Soils..5.6.4.3.94Cohesive Soils5.6.4.4Design Issues for Concrete Backfill of Predrilled Soldier Beam Holes...95...965.7ANCHOREDSLOPESANDLANDSLIDESTABILIZATIONSYSTEMS.5.7.1General.965.7.2Design Concepts..965.7.3Limit Equilibrium Calculations..975.7.3.1OverallApproach97vi
TABLE OF CONTENTS (Continued) vi 5.3.7 Spacing Requirements for Ground Anchors.75 5.3.8 Selection of Prestressing Steel Element .77 5.4 WALL DESIGN BASED ON LATERAL PRESSURES .78 5.4.1 Design of Soldier Beams and Sheet-Piles.78 5.4.2 Design of Lagging for Temporary Support .81 5.4.3 Design of Wales and Permanent Facing .83 5.5 LATERAL CAPACITY OF EMBEDDED PORTION OF WALL.84 5.5.1 General.84 5.5.2 Evaluation of Ultimate Passive Resistance .84 5.5.2.1 Soldier Beam and Lagging Walls .84 5.5.2.2 Continuous Walls.86 5.5.3 Depth of Penetration below Excavation.86 5.5.4 Comparison of Wang-Reese and Broms Method for Competent Soils.87 5.6 AXIAL CAPACITY OF WALL.88 5.6.1 Introduction.88 5.6.2 Axial Load Evaluation.89 5.6.3 Axial Capacity Design of Driven Soldier Beams.90 5.6.3.1 General.90 5.6.3.2 Effective Stress Analysis for Driven Soldier Beams.90 5.6.3.3 Total Stress Analysis for Driven Soldier Beams in Clays.92 5.6.4 Axial Capacity Design Of Drilled-in Soldier Beams.93 5.6.4.1 General.93 5.6.4.2 Cohesionless Soils.93 5.6.4.3 Cohesive Soils .94 5.6.4.4 Design Issues for Concrete Backfill of Predrilled Soldier Beam Holes.95 5.7 ANCHORED SLOPES AND LANDSLIDE STABILIZATION SYSTEMS.96 5.7.1 General.96 5.7.2 Design Concepts.96 5.7.3 Limit Equilibrium Calculations.97 5.7.3.1 Overall Approach.97
TABLE OF CONTENTS (Continued)5.7.3.2.98Method 1 Analysis5.7.3.3.100Method2Analysis5.7.4Modeling Lateral Wall Resistance in Limit Equilibrium Analyses.1015.7.5Comparison of Methods to Evaluate Required Earth Load in Homogeneous.102Soils.1055.8GROUNDMASSSTABILITY5.8.1...105Introduction...1055.8.2Basal Stability.5.8.2.1.105General..1055.8.2.2Evaluation of Bottom Heave Potential in Soft to Medium Clays..1075.8.3Extermal Stability5.8.3.1107Introduction5.8.3.2Evaluation of External Stability Using Limit Equilibrium.108..1095.9TIEDOWNDESIGN..5.9.1 Introduction.1095.9.2UpliftCapacityof RockTiedownAnchors..109..1105.9.3UpliftCapacityof SoilTiedownAnchors5.9.4Design of Tiedown Anchors to Resist Hydrostatic Uplift..1125.10SEISMICDESIGN..113.1135.10.1Introduction5.10.2 Internal Stability Using Pseudo-Static Theory...1135.10.2.1.113Lateral EarthPressure5.10.2.2Wall Design Consideration1165.10.2.3.117Liquefaction.5.10.3 Extermal Stability.1175.10.3.1117Pseudo-Static Analysis5.10.3.2Seismic Deformation Analysis..118价.1195.11 OTHERDESIGNISSUES1195.11.1 Wall and Ground Movements.5.11.2 Drainage Systems for Anchored Walls and Slopes120vii
TABLE OF CONTENTS (Continued) vii 5.7.3.2 Method 1 Analysis.98 5.7.3.3 Method 2 Analysis.100 5.7.4 Modeling Lateral Wall Resistance in Limit Equilibrium Analyses.101 5.7.5 Comparison of Methods to Evaluate Required Earth Load in Homogeneous Soils .102 5.8 GROUND MASS STABILITY.105 5.8.1 Introduction.105 5.8.2 Basal Stability.105 5.8.2.1 General.105 5.8.2.2 Evaluation of Bottom Heave Potential in Soft to Medium Clays .105 5.8.3 External Stability.107 5.8.3.1 Introduction.107 5.8.3.2 Evaluation of External Stability Using Limit Equilibrium.108 5.9 TIEDOWN DESIGN .109 5.9.1 Introduction.109 5.9.2 Uplift Capacity of Rock Tiedown Anchors.109 5.9.3 Uplift Capacity of Soil Tiedown Anchors.110 5.9.4 Design of Tiedown Anchors to Resist Hydrostatic Uplift.112 5.10 SEISMIC DESIGN.113 5.10.1 Introduction.113 5.10.2 Internal Stability Using Pseudo-Static Theory.113 5.10.2.1 Lateral Earth Pressure.113 5.10.2.2 Wall Design Considerations.116 5.10.2.3 Liquefaction.117 5.10.3 External Stability.117 5.10.3.1 Pseudo-Static Analysis.117 5.10.3.2 Seismic Deformation Analysis.118 5.11 OTHER DESIGN ISSUES.119 5.11.1 Wall and Ground Movements.119 5.11.2 Drainage Systems for Anchored Walls and Slopes.120
TABLE OF CONTENTS (Continued)1215.11.3 Wall System Appurtenances.1225.11.4 Resisting the Upper Anchor Test Load1225.11.5 Anchored Walls forFill ApplicationsCHAPTER6CORROSIONCONSIDERATIONSINDESIGN1246.1 INTRODUCTION.1246.2CORROSIONANDEFFECTSONGROUNDANCHORS.....124.1246.2.1 Mechanismof Metallic Corrosion1246.2.2Types of CorrosionforPrestressing Steel.6.3CORROSIONPROTECTIONOFGROUNDANCHORS..1266.3.1 RequirementsofCorrosionProtectionSystems...126.1266.3.2Design of Corrosion Protection Systems6.3.2.1.126General6.3.2.2.131Anchorage Protection6.3.2.3.132Unbonded Tendon Length Protection.6.3.2.4132Tendon Bond Length Protection.6.3.2.5.132Protection Against Stray Currents.6.3.2.6CorrosionProtectionofAnchorsforStructuresSubjecttoHydrostaticUplift..133..1336.4SELECTIONOFCORROSIONPROTECTIONLEVEL.1336.4.1General.1336.4.2Service Life of the Anchored Structure6.4.3..133Aggressivity of the Ground Environment...1356.4.4ConsequencesofFailureoftheAnchored System.6.4.5 Cost for a Higher Level of Protection1356.5CORROSIONOFSTRUCTURALSTEEL,CEMENTGROUT,ANDCONCRETE.135.1356.5.1Corrosion and Protection of Steel Soldier Beams and Sheet Piles.6.5.2Degradation and Protection of Cement Grout and Concrete136vili
TABLE OF CONTENTS (Continued) viii 5.11.3 Wall System Appurtenances.121 5.11.4 Resisting the Upper Anchor Test Load .122 5.11.5 Anchored Walls for Fill Applications.122 CHAPTER 6 CORROSION CONSIDERATIONS IN DESIGN.124 6.1 INTRODUCTION .124 6.2 CORROSION AND EFFECTS ON GROUND ANCHORS.124 6.2.1 Mechanism of Metallic Corrosion.124 6.2.2 Types of Corrosion for Prestressing Steel.124 6.3 CORROSION PROTECTION OF GROUND ANCHORS .126 6.3.1 Requirements of Corrosion Protection Systems.126 6.3.2 Design of Corrosion Protection Systems.126 6.3.2.1 General.126 6.3.2.2 Anchorage Protection.131 6.3.2.3 Unbonded Tendon Length Protection.132 6.3.2.4 Tendon Bond Length Protection.132 6.3.2.5 Protection Against Stray Currents.132 6.3.2.6 Corrosion Protection of Anchors for Structures Subject to Hydrostatic Uplift .133 6.4 SELECTION OF CORROSION PROTECTION LEVEL.133 6.4.1 General.133 6.4.2 Service Life of the Anchored Structure .133 6.4.3 Aggressivity of the Ground Environment.133 6.4.4 Consequences of Failure of the Anchored System.135 6.4.5 Cost for a Higher Level of Protection.135 6.5 CORROSION OF STRUCTURAL STEEL, CEMENT GROUT, AND CONCRETE.135 6.5.1 Corrosion and Protection of Steel Soldier Beams and Sheet Piles.135 6.5.2 Degradation and Protection of Cement Grout and Concrete.136