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Transcript
Materials&
Installation Techniques for
Retaining Wall
Contents
• What is retaining wall?
• Types of retaining wall.
• Design consideration
• Wall Material
• Installation Techniques
What is Retaining Wall?
• A retaining wall is a structure designed and constructed to resist the lateral pressure of soil when there is a desired change in ground elevation that exceeds the angle of repose of the soil.
• Retaining walls are structures designed to restrain soil to unnatural slopes. They are used to bound soils between two different elevations.
Cont…
• It is either constructed for Engineering purpose or for Aesthetic purpose.
• It is used in the area of undesirable slope.
• It is constructed to resist the lateral pressure of soil.
Pictures of
Retaining Wall
Types of Retaining Wall
Gravity Cantilevered Sheet Piling
Bored Piling Anchored
Gravity Wall
• Gravity walls depends on their masses to resist pressure of soil.
Anchored Wall
Cantilevered Wall
Piling Wall
Design Consideration
A gravity retaining wall must have sufficient weight and width so that it does not overturn.
The wall must also be able to hold together as a unit in order to function.
The wall must be stable with respect to both the external forces that might cause it to fall and the internal forces that might cause it to lose its shape and/or deformed.
WALL MATERIALS
Selection of wall material:
Purpose of wall either for Engineering or for aesthetic.
It should has low environmental impact.
Can withstand forces of nature without compromising the environment.
Cont…
It should be economical.
Choice of the client.
Availability of material in that area.
Materials such as stones and some woods can be reused.
Various Wall Materials: Railroad ties
Cont…
• Railroad ties are least expensive wall material
• Ties provide gray to dark brown color to wall
• They blend well with the naturalistic theme
But
• Availability of good quality ties is limited since the late 1980’s
• Ties requires a great deal of sorting to match dimensions.
Railroad Tiesused as retaining wall
Landscape Timber:
Landscape Timber:
• Timbers are good but costly substitute of ties.
• They are manufactured to consistent length and dimensions.
• Mostly 6-inch x 6-inch or 8-inch x 8-inch dimensions and 6-8 ft length.
• They also have consistent wall texture and color.
• Timbers weight is slightly less than the Ties.
Timbers in landscaping
Segmental Wall Unit
Segmental Wall Unit:
• They are similar in surface area to concrete.
• These Wall units comes in variety of forms and shapes.
• They provide an attractive and consistent wall surface.
• Wall units can be heavy(30-80 lb per unit).
• Installation requires careful layout and base course preparation.
• Their cost is from mid to slightly high range.
Segmental Wall unit in landscaping
Dry-Laid Stone
Dry-Laid Stone:
• It is considered as the classic wall material.
• This natural wall material is installed without mortar between the stones.
• It is considered as highly aesthetic wall material.
• Stone wall can be constructed of random or regular thickness and with a variety of stones.
• Requires intensive labor for preparation and installing.
Dry-laid Stone in
landscaping
Gabions
Gabion:
• Gabion is derived form Italian word gabion meaning “big cage”.
• A heavy duty rectangular wire basket placed in position and filled with stones.
• Different aesthetic effects can be produced by varying the size of the stones.
• Presence of wire basket is always be a detraction.
• The cost is in the lower range.
Use of gabion in landscaping
Alternative Materials:
• Man is always looking for more and better.
• Other than above discussed material there are few more materials.
• Such as old concrete paving, old tyres etc.
Installation Techniquesof
Retaining Wall
Wall Layout:
• Prior to construction identify the location of wall.
• Placing stakes and straight lines.
• Also identify the location of stairs & corners.
• This will guide the rough trenching necessary.
Excavation:
• Excavation is required where the wall is to be construct.
• Topsoil is excavated from an area 2ft in front and 2ft behind the entire wall alignment.
• Excavated to a depth which is lower than the desired finished depth.
Base Preparation:
• Base material is 6inch deep & 12inch wider than the wall material as shown in fig.
• The bottom or base of the trench should be level from end to end.
• Fill the trench with crushed stones (¾-1inch) for draining purpose.
• Level the base material and compact using compactor.
Flowable Fill:
• A stable alternative to compacted granular base material is Flowable fill.
• To install it excavate the trench minimum of 24inch wide & 12inch deep.
• Flowable fill should be liquid enough to seek its own level without finishing.
Grade Beams:
• It is required where the soil is highly unstable.
• Construction starts with excavation and pouring the piers in the location.
• Under the alignment of footing, excavates and place minimum 2inch of sand.
Landscape Fabric:
• Certain wall material have open joints to allow backfill material to pass.
• To reduce it landscape fabric is placed behind the compacted fill.
• But it is not suggested mostly because it increase the hydrostatic pressure.
Wall Height & Stabilization:
• As the height of wall increases it potential of failure also increases.
• To prevent this failure typical measures are used including:Placing the buttresses in front of timber walls.
Installing the wall anchors.
Terracing.
Thank you
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