MSE Wall Design. MSE Wall as a Gravity Wall An MSE wall is a gravity wall.An MSE wall is a gravity wall. Heavy walls are good

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<ul><li>Slide 1</li></ul> <p>MSE Wall Design Slide 2 MSE Wall as a Gravity Wall An MSE wall is a gravity wall.An MSE wall is a gravity wall. Heavy walls are good Slide 3 External Stability Bearing resistanceBearing resistance SettlementSettlement SlidingSliding OverturningOverturning Overall StabilityOverall Stability Slide 4 External Stability Bearing Slide 5 Bearing Failure Slide 6 External Stability Settlement Slide 7 1.2-7 Flexibility of Wall Systems TYPE OF FACING LIMIT OF DIFFERENTIAL SETTLEMENT CIP Gravity Wall 1/500 2 In. in 100 Ft. Welded Wire Facing 1/50 2 Ft. in 100 Ft. 5 x 5 Panels with Joints 1/100 1 Ft. in 100 Ft. 5 x 10 Panels with Joints 1/200 6 In. in 100 Ft. Modular Block Walls 1/200 6 In. in 100 Ft. Full Height Facing Panels 1/500 2 In. in 100 Ft. Slide 8 External Stability Sliding Slide 9 Sliding Failure Slide 10 External Stability Overturning Slide 11 Overall Stability Slide 12 Forces Water Pressure Earth Pressure Surcharge Earthquake Slide 13 Forces Back Slope Surcharge Slide 14 Forces Surcharge Slide 15 Drainage If the wall backfill fills with water .If the wall backfill fills with water . Weight of soil increases Weight of soil increases Shear strength of backfill decreases Shear strength of backfill decreases Pressures on the wall increase Pressures on the wall increase Greater tendency for fill to settle Greater tendency for fill to settle Potential for movement of soils as water exits wall or slope. Potential for movement of soils as water exits wall or slope. Buoyancy needs to be considered Buoyancy needs to be considered Appropriate drainage systems are critical !!Appropriate drainage systems are critical !! Slide 16 Drainage System Installation Slide 17 Why Care about Drainage? An example Slide 18 20 5 Slide 19 5 H w =20 LATERAL EARTH PRESSURES H=25 Slide 20 Design Concepts Topic 2 Internal Stability Design of MSE Walls Slide 21 What is a Failure Surface ?? Geosynthetic Reinforced Wall H L Active Zone Resistant Zone Potential Failure Surface Soil Reinforcement Reinforced Soil Mass Metal Reinforced Wall Slide 22 How do Reinforcements Hold Up the Wall ? L Soil Reinforcement Active Force Resistant Length, L e Active Length, L a Slide 23 Internal Stability Reinforcement Failure Modes Pull outPull out Reinforcement tensile strengthReinforcement tensile strength ConnectionConnection Slide 24 Internal Stability Reinforcement Failure Modes CORROSION/DEGRADATION STEEL REINFORCEMENTSTEEL REINFORCEMENT Area of steel is increased to account for the anticipated corrosion loss over the design life Area of steel is increased to account for the anticipated corrosion loss over the design life GEOSYNTHETIC REINFORCEMENTGEOSYNTHETIC REINFORCEMENT Ultimate tensile strength increased to account for strength loss due to installation damage, creep, and durability Ultimate tensile strength increased to account for strength loss due to installation damage, creep, and durability Slide 25 The internal stability of this wall seems OK! Compare the internal stability of the Design MSE wall and the As-Built MSE WallCompare the internal stability of the Design MSE wall and the As-Built MSE Wall Design Checks Slide 26 Continuous Geogrid Reinforcement H = 20 ft L = 20 ft 2 1 Section Backfill Medium sand with 15% (max) non- plastic fines at 95% compaction Spacing 18 Chimney Drain 4 ft 3 ft 3 1 Turf reinforcement mat, topsoil, and seedDesign Slide 27 H = 25 ft L = 20 ft 1.5 1 PlanSection L = 15 ft Backfill Medium sand with 35% plastic fines at 95% compaction Spacing 36 Geogrid Reinforcement Note: Geogrid Coverage = 50% 2 ft 2 1 As-Built Slide 28 Durability MSE WallsMSE Walls Corrosion of steel reinforcement Corrosion of steel reinforcement Degradation of geosynthetic reinforcement Degradation of geosynthetic reinforcement Durability of the facing Durability of the facing Slide 29 1.2-29 MSE Facing Durability </p>