VERSION 2.1 5/6/2019 GEOTECHNICAL DESIGN MANUAL CHAPTER 15- RETAINING STRUCTURES GEO-ENVIRONMENTAL SECTION OREGON DEPARTMENT OF TRANSPORTATION CHAPTER 15- RETAINING STRUCTURES TABLE OF CONTENTS SUMMARY OF CHANGES ............................................................................................................................... 6 15 RETAINING STRUCTURES .................................................................................................................. 7 15.1 INTRODUCTION ...........................................................................................................................................8 15.2 RETAINING WALL PRACTICES AND PROCEDURES ....................................................................................8 15.2.1 RETAINING WALL CATEGORIES AND DEFINITIONS ................................................................ 8 15.2.2 GENERAL STEPS IN A RETAINING WALL PROJECT ................................................................ 14 15.2.3 RETAINING WALL PROJECT SCHEDULE ................................................................................ 15 15.2.4 SELECTION OF RETAINING WALL SYSTEM TYPE ................................................................... 16 15.2.5 PROPRIETARY RETAINING WALL SYSTEMS .......................................................................... 19 15.2.6 NONPROPRIETARY RETAINING WALL SYSTEMS .................................................................. 19 15.2.7 UNIQUE NONPROPRIETARY WALL DESIGNS ........................................................................ 20 15.2.8 DETAILS OF CONTRACT DOCUMENTS .................................................................................. 20 15.3 DESIGN REQUIREMENTS: GENERAL WALL DESIGN ............................................................................... 25 15.3.1 DESIGN METHODS ............................................................................................................... 25 15.3.2 WALL FACING CONSIDERATIONS ......................................................................................... 25 15.3.3 WALL FACE ANGLE (BATTER) ............................................................................................... 26 15.3.4 HORIZONTAL WALL ALIGNMENT ......................................................................................... 26 15.3.5 TIERED OR SUPERIMPOSED WALLS ..................................................................................... 27 15.3.6 BACK-TO-BACK WALLS ......................................................................................................... 27 15.3.7 WALL BENCH ........................................................................................................................ 28 15.3.8 WALL BACK SLOPE ............................................................................................................... 28 15.3.9 WALL STABILITY ................................................................................................................... 28 15.3.10 LATERAL EARTH PRESSURES ............................................................................................... 28 15.3.11 COMPACTION LOADS .......................................................................................................... 30 15.3.12 CONSTRUCTION SURCHARGE LOADS ................................................................................. 31 15.3.13 SEISMIC DESIGN .................................................................................................................. 32 15.3.14 MINIMUM FOOTING EMBEDMENT .................................................................................... 32 15.3.15 FOUNDATION SETTLEMENT SERVICEABILITY CRITERIA ...................................................... 32 15.3.16 GROUNDWATER MONITORING .......................................................................................... 34 15.3.17 SEISMIC HAZARDS ............................................................................................................... 35 15.3.18 WALL SUBSURFACE DRAINAGE ........................................................................................... 35 15.3.19 UNDERGROUND UTILITIES .................................................................................................. 36 15.3.20 DESIGN LIFE ......................................................................................................................... 36 15.3.21 CORROSION PROTECTION ................................................................................................... 36 GEOTECHNICAL DESIGN MANUAL Page 2 of 132 CHAPTER 15- RETAINING STRUCTURES 15.3.22 RAILING ............................................................................................................................... 37 15.3.23 PROPRIETARY MINOR RETAINING WALL SYSTEMS ............................................................. 38 15.3.24 NONPROPRIETARY MINOR RETAINING WALL SYSTEMS ..................................................... 38 15.3.25 WALL BACKFILL TESTING AND DESIGN PROPERTIES ........................................................... 39 15.3.26 TEMPORARY SHORING AND CUT SLOPES ........................................................................... 39 15.3.27 TEMPORARY RETAINING WALLS ......................................................................................... 43 15.4 CIP CONCRETE RIGID GRAVITY WALLS ................................................................................................... 45 15.4.1 GENERAL CONSIDERATIONS ................................................................................................ 45 15.4.2 GEOTECHNICAL INVESTIGATION.......................................................................................... 45 15.4.3 WALL SELECTION CRITERIA .................................................................................................. 45 15.4.4 WALL HEIGHT, FOOTPRINT AND CONSTRUCTION EASEMENT ............................................ 45 15.4.5 DESIGN REQUIREMENTS ...................................................................................................... 46 15.4.6 CONCRETE GRAVITY RETAINING WALLS .............................................................................. 46 15.5 CIP CONCRETE SEMI-GRAVITY CANTILEVER WALLS .............................................................................. 46 15.5.1 GENERAL CONSIDERATIONS ................................................................................................ 46 15.5.2 GEOTECHNICAL INVESTIGATION.......................................................................................... 47 15.5.3 WALL SELECTION CRITERIA .................................................................................................. 47 15.5.4 WALL HEIGHT, FOOTPRINT, AND CONSTRUCTION EASEMENT ........................................... 47 15.5.5 DESIGN REQUIREMENTS ...................................................................................................... 47 15.6 MECHANICALLY STABILIZED EARTH (MSE) WALLS AND REINFORCED SLOPES ................................... 48 15.6.1 GENERAL CONSIDERATIONS ................................................................................................ 49 15.6.2 GEOTECHNICAL INVESTIGATION.......................................................................................... 49 15.6.3 WALL SELECTION CRITERIA .................................................................................................. 49 15.6.4 WALL HEIGHT, FOOTPRINT, AND CONSTRUCTION EASEMENT ........................................... 50 15.6.5 MINIMUM WALL EMBEDMENT ........................................................................................... 50 15.6.6 EXTERNAL STABILITY ANALYSIS ............................................................................................ 50 15.6.7 INTERNAL STABILITY ANALYSIS ............................................................................................ 52 15.6.8 WALL DRAINAGE .................................................................................................................. 53 15.6.9 TRAFFIC RAILING .................................................................................................................. 53 15.6.10 CORROSION ......................................................................................................................... 57 15.6.11 TWO-STAGE FACING (MSE RETAINING WALL SYSTEMS) .................................................... 57 15.6.12 (RESERVED FOR FUTURE USE)............................................................................................. 58 15.6.13 TIERED OR SUPERIMPOSED WALLS .................................................................................... 58 15.6.14 BACK-TO-BACK WALLS ........................................................................................................ 58 15.6.15 MSE AND GRS-IBS BRIDGE RETAINING WALLS ................................................................... 58 GEOTECHNICAL DESIGN MANUAL Page 3 of 132 CHAPTER 15- RETAINING STRUCTURES 15.6.16 TEMPORARY GEOTEXTILE-REINFORCED MSE WALL ........................................................... 64 15.7 PREFABRICATED MODULAR WALLS ....................................................................................................... 67 15.7.1 METAL AND PRECAST CONCRETE BIN RETAINING WALLS ................................................... 68 15.7.2 PRECAST CONCRETE CRIB RETAINING WALLS 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