THEORY OF STRUCTURES
Presented by: SHARIQUE
B.Arch 3rd yr
• Retaining walls are used to retain earth or
other materials which have the tendency to
slide and repose at a particular inclination.
• They provide lateral support to the earthfill,
embankments or other materials in order to
hold them in a vertical position.
• Retaining walls also have application in
buildings and bridges such as basement,
foundation wall, bridge abutment etc.
The primary geotechnical concern in design and installation of
retaining walls is that the retained material is attempting to move
forward and down slope due to gravity.
This creates soil pressure behind the wall, which can be analysed
based on the angle of internal friction (φ) and the cohesive strength (c)
of the material and the amount of allowable movement of the wall.
This pressure is smallest at the top and increases toward the bottom
in a manner similar to hydraulic pressure, and tends to push the wall
forward and overturn it.
Groundwater behind the wall that is not dissipated by a drainage
system causes an additional horizontal hydraulic pressure on the wall.
1.GRAVITY RETAINING WALL
• A gravity wall is made of plain concrete or brick masonry.
• The stability of the wall is maintained by its weight.
• It is generally made up to a height of 3 m of wall.
2.CANTILEVER RETAINING WALL
• It consists of a vertical wall, heal slab
and a toe slab which act as cantilever
• Its stability is maintained by the
weight of the retaining wall and the
weight of the earth on the base of the
• It is generally made when the height
of the earth on the base is in the
range of 3 m to 8 m.
WALL height of retaining wall is more than 6-8m, it is
• When the
economical to tie the vertical wall with the heel slab by counter
forts at some spacing.
• The counterforts act as tension members to support the vertical
wall and reduces bending moment in it.
• It also provides support to heel slab.
• Generally, counterforts are spaced at approximately one-third of
the height of wall.
4. BUTTRESS RETAINING WALL
• It is similar to counter fort wall except that the vertical wall
is tied with the toe of the retaining wall at some spacing.
• It acts as a compression member to support the vertical wall
and reduces bending moment in it.
5. 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; and
6. Their joints are less apt to deform during driving
6. BRIDGE RETAINING WALL
• Its behaviour is similar to that of the basement or
• The bridge superstructure induces horizontal as well as
vertical loads that alter the normal cantilever behaviour.
7.MECHANICALLY STABILISED EARTH
• Mechanically stabilized earth or MSE is soil constructed with
artificial reinforcing. It can be used for retaining walls, bridge
abutments, dams, seawalls, and dikes.
• Although the basic principles of MSE has been used throughout
history, MSE was developed in its current form in the 1960s.
• The reinforcing elements used can vary but include steel and
• Mechanically stabilized earth (MSE) retaining walls
combine geosynthetic-reinforced earth layers (such as
geogrids) and a fascia of geocell, wire mesh or concrete
blocks to create high-strength, versatile earth retention
• The geogrid reinforces the soil while the fascia protects the
• The versatility of MSE walls makes them suitable for a
variety of applications, from road structures to golf
REINFORMENT IN MSE
• The reinforcement materials of MSE can vary.
• Originally, long steel strips 50 to 120 mm (2 to 5 in)
wide were used as reinforcement. These strips are
sometimes ribbed, although not always, to provide
• Steel grids or meshes are also used as
• Several types of geosynthetics can be used including
geogrids and geotextiles. The reinforcing
geosynthetics can be made of high density
polyethylene, polyester, and polypropylene.
EARTH PRESSURE ON RETAINING
Earth pressure may be calculated at the vertical section going
through the heel of the wall.
This is under the constraint that heel is propotional in such a way
that line AC makes an angle less than or equal to n with vertical.
Advantages of retaining walls
• A retaining wall provides advantages such as
▫ preventing damage by soil falling or
▫ sliding away from a foundation.
▫ This can preserve ground area on the property or
even add to it.
DISADVANTAGES OF RETAINING
• Vertical Cracks
▫ Vertical cracks may form in retaining walls.
▫ Some retaining walls begin developing vertical cracks, such as in
poured concrete. This is often due to excessive pressure or wide
changes in temperature. In order to prevent these vertical cracks,
provide plenty of good drainage, which can often be expensive to
• Failing Foundation
▫ Brick retaining walls often fail under pressure.
▫ Retaining walls need extensive drainage resources to prevent
moisture, but they also require a strong foundation. Some
retaining walls will not be able to retain high amounts of pressure
from soil, such as bricks walls. This often results in crumbling
bricks or a failing foundation.
▫ Termites are sometimes found in timber retaining walls.
▫ Retaining walls also can attract termites to your property, as is
often the case when timber is used as a retaining wall. Termites
can nest inside rotting timber and near molded areas. Correcting
this problem can be expensive, if you have to use termite
monitoring and treatment devices.
MSE Precast Panel
• Reinforced Earth retaining walls are coherent gravity
structures consisting of alternating layers of granular
backfill and high-strength, inextensible discrete steel strip
soil reinforcement with a modular precast concrete facing.
• They are used extensively in highway projects for retaining
walls and bridge abutments, in seawalls, dams, bulk storage
facilities, and in supporting various types of railway transit.
Retained Earth – MSE Precast Panel
• Retained Earth retaining walls are coherent gravity
structures consisting of alternating layers of granular
backfill and high-strength, inextensible, highadherence welded wire bar mat soil reinforcement with
a modular precast concrete facing.
• They are used extensively in highway projects for
retaining walls and bridge abutments, in seawalls,
dams, bulk storage facilities, and in supporting various
types of railway transit.
Terratrel– MSE Wire Faced
• Terratrel is a wire-faced MSE wall system that combines the
technology of Reinforced Earth and Retained Earth with the
economy of wire facing.
• The system provides a cost-effective alternative for wall
applications where aesthetics are not critical, a temporary
retaining structure is required or differential and overall
settlement exceeds the limits for a one-stage precast panel
• The Terratrel system can be designed to utilize discrete steel
strip, welded wire bar mat or high-tenacity polyester based
geostrap soil reinforcements.
GeoMega– MSE Precast Panel
• GeoMega retaining walls are coherent gravity structures
consisting of alternating layers of granular backfill and a hightenacity polyester based geostrap soil reinforcement with a
modular precast concrete facing.
• The Omega strip consists of high tenacity polyester fibers
encased in a polyethylene sheath which makes it ideal for use in
the construction of walls in where sea water or other chemically
aggressive environments preclude the use of galvanized steel soil
Piano Wall – MSE Precast Retaining
Wall with Traffic Barrier
• Piano Wall is a MSE wall system which combines the
technology of a Reinforced Earth retaining wall topped with an
integral traffic barrier in a single engineered unit.
• This unique solution was developed for projects that require a
Jersey-type traffic barrier atop a five- to ten-foot high
Reinforced Earth retaining wall.
• It is ideal for projects requiring low-height grade separations
adjacent to bi-level roadways.
TechWall - Precast
• TechWall is a full height panel which combines a
precast counterfort and wall facing into one unit.
• When the traditional design advantages and benefits of
a typical counterfort retaining wall are recommended
due to items such as a severe right-of-way restriction,
large utility conflict, construction in cut conditions, and
roadway widening TechWall is an effective solution
which encompasses the quality and efficiency of precast
Fanwall - Noisewall /
• Fanwall is a precast modular permanent barrier wall system
which can be a freestanding trapezoidal structure or where
right-of-way is minimal, a post and panel alternative is
• A unique, rotatable and interlocking connection system and
limitless architectural finishes makes Fanwall extremely
• This engineered barrier wall system is available for nearly
every noise or security problem found in the transportation,
utility, industrial, and commercial markets.
RE/Tension - Precast
• RE/Tension consists of integral precast box attached to the
back of a standard MSE wall facing panel, the box serves as a
form for a cast-in-place concrete counterfort.
• This system is ideally suited for retaining walls with right-ofway constraints, large utility conflicts and full or partial rock
• Since the facing is comprised of standard MSE wall panels the
RE/Tension system can be easily combined with a Reinforced
Earth retaining wall within the same structure, while
maintaining an identical aesthetic appearance.
ADVANTAGES OF MECHANICALLY
STABILISED RETAINING WALLS
The use of heavy equipment is reduced.
More land is available for construction.
Faster construction than traditional concrete walls.
Do not require specialized labor.
Reduces the need for wall finishing.
Less site prep is needed.
Can be built in confined areas or areas where a concrete wall is almost
impossible to be constructed.
Reduces the need for additional land acquisition process.
Mechanically Stabilized Earth walls are susceptible to elastic deformation.
High seismic load resistance.
MSE walls can be used as tall structures, exceeding more than 60 feet of wall
Can be combined with other products.
Various shapes and forms can be made.
Excavation works for footings are reduced.
Can be built on poor soil areas.
DISADVANTAGES OF MSE
• Require a relatively large space behind the wall or outward face to
obtain enoughwall width for internal and external stability.
• MSEW require select granular fill. (At sites where there is a lack of
granular soils,the cost of importing suitable fill material may render
the system uneconomical).
• Requirements for RSS are typically less restrictive.
• Suitable design criteria are required to address corrosion of steel
reinforcingelements, deterioration of certain types of exposed facing
elements such asgeosynthetics by ultra violet rays, and potential
degradation of polymer reinforcementin the ground.
• Since design and construction practice of all reinforced systems are
still evolving,specifications and contracting practices have not been