2.
Retaining Walls
A retaining wall is a wall
built to support or
prevent the advance of a
mass of earth or water.
More beautifying form
of negative drainage
correction.
3. What is a Retaining Wall
A retaining wall is generally defined as a vertical wall that holds back earth.
Uses of Retaining Wall
A retaining wall for roadside embankments
A retaining wall can separate older roads from highways
A house retaining wall for the garage
A retaining wall helps keep river banks from eroding
A retaining wall to keep earth from stairwells and driveways
Retaining Wall Construction
Some retaining wall construction types are:
A concrete retaining wall
An interlocking block retaining wall
A Wood retaining wall
An Insulated Concrete Form retaining wall or ICF retaining wall
After the retaining wall construction is complete,
The retaining wall is then backfilled on one side only.
Backfilling on one side of the retaining wall creates an extreme amount of pressure.
This pressure comes from the weight of the earth and the moisture in the soil.
This pressure can result in cracks and water seepage in the retaining wall.
Some of those effects are:
Green slime
Efflorescence
Mineral deposits
Rust from wall tie
Freeze and thaw cycles also creates extra stress on a retaining wall.
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6. Reinforced earth wall structures are a system whereby mesh layers are
introduced into the soil backfill as a reinforcement to provide stability.
The system can use mesh, gabions, concrete block or panels as a facing.
The types of mesh reinforcement selected can be geogrid (polymer mesh),
woven wire hexagonal steel mesh (same as rock netting), welded wire steel
mesh or steel strap/ladder systems.
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8. Crib Walls.
Crib walls are made up of interlocking individual boxes made from timber or
pre-cast concrete.
The boxes are then filled with crushed stone or other coarse granular materials
to create a freedraining
structure. There are two basic types of crib wall:
- Timber, and
- Reinforced pre-cast concrete.
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9. Gabion walls.
Gabions are multi-celled, welded wire or rectangular wire mesh boxes, which are
then rock filled,
and used for construction of erosion control structures and to stabilize steep
slopes. Their
applications include,
- Retaining walls,
- Bridge abutments,
-Wing walls,
- Culvert headwalls,
- Outlet aprons,
- Shore and beach protection walls, and
- Temporary check dams- dams.
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10. A crane is lifting a wall form to cast this reinforced-retaining wall.
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11. The first MSE wall built in Florida was for Metro-Rail’s Medley Yard. The first step was to build
this temporary soldier pile and lagging wall to retain the Hialeah Expressway (NW 74th Street).
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13. Soil Nailing
~ steel rods placed into holes drilled into the walls
and grouted
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14. Geofabrics
~ used for reinforcement, separation, filtration and
drainage in roads, retaining walls, embankments…
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Geofabrics used on Pacific Highway
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15. Typical Safety Factors
Type of Design
Safety
Factor
Probability of
Failure
Earthworks
1.3-1.5
1/500
Retaining
structures
1.5-2.0
1/1500
Foundations 2.0-3.0
1/5000
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16. Polymeric reinforcement
use of geo-textile made from synthetic polymers
using polyethylene, polyamides, polyester,
polypropylene; woven, non-woven or
extruded bi-axial or uni-axial grids, sheets,
etc, for reinforced fill/soil walls.
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17. Mechanically Stabilized Earth (MSE) Walls.
These walls are among the most economical, and most commonly constructed.
Contrary to other types, the MSE walls are supported by the soil, and not the
other way around.
They are supported by selected fills (granular) and held together by
reinforcements, which can be either metallic strips or plastic meshes.
The MSE Categories.
A) Panel Walls,
B) Concrete Block Walls, and
C) Temporary Earth Walls.
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18. A typical MSE wall provides the advantage of cheaper walls
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19. Sheet Pile Walls.
Used to build continuous walls for waterfront structures and for temporary
construction wall heights > 6 m if used with anchors.
Can be made of steel, plastics, wood, pre-cast concrete.
The advantages of using steel sheet-piling:
1. Provides higher resistance to driving stresses;
2. Is of an overall lighter weight;
3. Can be reused on several projects.
4. Provides a long service life above or below the water table
5. Easy to adapt the pile length by either welding or bolting .
6. Their joints are less apt to deform during driving.
This bridge is being widened, and the traffic is maintained with this temporary sheeting.
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20. Sheet Piles
~ resist lateral earth pressures
~ used in excavations, waterfront structures, ..
~ interlocking sections
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