There are several types of retaining walls used to resist lateral soil pressure, including: 1) Gravity retaining walls which rely on mass to resist sliding and overturning forces. 2) Piling retaining walls which extend below grade for support. 3) Cantilever retaining walls which use soil placed over a horizontal section for stability. 4) Anchored walls which use cables driven into the soil to counteract horizontal forces. Many walls combine types, such as piling walls using anchors to reduce embedment. Wall design considers stability, structural strength, and adjacent impacts. Stability depends on factors of safety against sliding, overturning, bearing failure, and surrounding soil slope failure.

1. EARTH RETAINING STRUCTURES &
TYPES OF RETAINING WALL

2. Earth Retaining Structures
Any wall that sustains significant lateral soil pressure is a retaining wall.
However, the term is usually used with reference to a cantilever retaining wall,
which is a freestanding wall without lateral support at its top.
The range of its dimensions establishes some different categories for the retaining
structure .
 Short Retaining Walls
 Tall Retaining Walls

3. Earth Retaining Structures
 Short Retaining Walls:
Vertical walls up to about 3m in height are usually built, these consists of a
concrete or masonry wall of uniform thickness.
 Tall Retaining Walls:
As the wall height increase the overturning moment increases sharply with the
increase in height of the wall. For very tall walls one modification used is to taper
the wall thickness. This permits the development of a reasonable cross section for
the high bending stress at the base without an excessive amount of concrete.

4. RETAINING WALLS
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.
The design of the wall must:
 Resist sliding along its base.
 Resist overturning.
 Not exceed the bearing capacity of the soil beneath the base.
 Avoid excessive settlement.
 Built structurally strong to resist failure from the build up of internal stresses
produced by external forces.

5. Types Of Retaining Walls
GRAVITY RETAINING WALLS:
They rely on the mass of the wall structure for stability. The wall mass must be
sufficient to counteract sliding and overturning forces from the retained soil.
These systems can use stone, concrete or other heavy Material. These are he
most common type of retaining walls.
In most cases the slope behind the wall needs to be temporarily removed during
construction. For mechanically stabilized earth walls, the reinforcing often
extends horizontally into the embankment about as far as the exposed wall face
is tall.

7. Types Of Retaining Walls
PILING RETAINING WALLS:
Piling retaining walls have structures that extend significantly below grade to
provide support to counteract horizontal forces from the retained soils.
Typically two thirds of the structure height is embedded below grade. These
are some of the most expensive types of retaining walls but they do allow
construction with very little removal of soil behind the wall.
CANTILEVER RETAINING WALLS:
Have a large effective mass due to the soil placed over a horizontal section of the
wall. These walls are typically constructed of cast-in-place, reinforced
concrete. Cantilever walls are relatively expensive due to the work required to
build concrete forms, install reinforcing, pour concrete, and provide joints
between pours.

9. Types Of Retaining Walls
ANCHORED WALLS:
Anchored (or tieback) retaining walls use cables driven horizontally into the soil
to counteract opposing horizontal forces from the retained soils. The anchors,
which typically pull horizontal plates or sheets against the soil, can be soil
nails, tieback cables, or screw anchors. The soil behind the wall does not need
to be removed during construction.
Combination:
Many retaining walls use a combination of the above types. For example, many
piling walls use anchors to reduce embedment depth and structure strength.

12. Design Considerations
In the design of retaining walls, the following aspects need to be investigated.
 The stability of soil around the wall
 The stability of retaining wall itself
 The structural strength of the wall
 Damage to adjacent structures due to wall construction.

13. Stability Of Retaining Wall
The stability of a retaining structure and the wall contained by it is
determined by computing factors of safety (or stability factors), which
may be defined in general terms as
Fs = Moments or forces aiding stability / moments or forces causing
instability
 Sliding of the wall outwards from the retaining soil
 Overturning of the retaining wall
 Foundation bearing failure
 Larger scale slope or other failure in the surrounding soil