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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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Presentation on theme: "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."— Presentation transcript:

1 MSE Wall Design

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

3 External Stability Bearing resistanceBearing resistance SettlementSettlement SlidingSliding OverturningOverturning Overall StabilityOverall Stability

4 External Stability Bearing

5 Bearing Failure

6 External Stability Settlement

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 ¾ Joints 1/100 1 Ft. in 100 Ft. 5 x 10 Panels with ¾ 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.

8 External Stability Sliding

9 Sliding Failure

10 External Stability Overturning

11 Overall Stability

12 Forces Water Pressure Earth Pressure Surcharge Earthquake

13 Forces Back Slope Surcharge

14 Forces Surcharge

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 !!

16 Drainage System Installation

17 Why Care about Drainage? An example…

18 20 5

19 5 H w =20 LATERAL EARTH PRESSURES H=25

20 Design Concepts Topic 2 Internal Stability Design of MSE Walls

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

22 How do Reinforcements Hold Up the Wall ? L Soil Reinforcement Active Force Resistant Length, L e Active Length, L a

23 Internal Stability Reinforcement Failure Modes Pull outPull out Reinforcement tensile strengthReinforcement tensile strength ConnectionConnection

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

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

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

27 H = 25 ft L = 20 ft 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

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

29 MSE Facing Durability


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