• 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, embankment or other
materials in order to hold them in a
Gravity retaining wall
Cantilever retaining wall
Counterfort retaining wall
Buttress retaining wall
GRAVITY RETAINING WALL
• Made of plain concrete or brick masonry.
• Stability of wall is maintained by its weight.
• Generally made up to a height of 3m of wall.
CANTILEVER RETAINING WALL
• Consists of a vertical wall, heal
slab & toe slab which act as
• Stability maintained by weight of
retaining wall & weight of earth
on the base of retaining wall.
• Height ranges from 3m to 8m.
COUNTERFORT RETAINING WALL
• Height ranges from 6m to 8m.
• More economical to tie the vertical wall with the heel slab by counterforts at
• Acts as tension member to support vertical wall & reduces bending moment.
• Supports the heel slab & reduces bending moment.
• Spacing: 1/3rd the height of wall.
• Stability maintained by weight of earth on base & by self-weight.
• More widely used as it is hidden beneath the retained materials.
• Has a clean, uncluttered face for more efficient use of space in front of wall.
BUTTRESS RETAINING WALL
• Similar to the counterfort wall.
• Vertical wall is tied with toe of retaining wall at some spacing.
• Acts as compression member to support vertical wall & reduces its bending
• Supports toe slab & reduces its bending moment.
• Spacing: 1/3rd the height of the wall.
• Buttress as compression member is more economical than a tension
• Restrained at the bottom by
basement floor slab & at the top by
the first floor slab.
• Subjected to:
Lateral earth pressure exerted by
Vertical load from superstructure.
• Lateral support is provided by
basement floor & first floor slabs.
• Behaviour similar to basement or
• Superstructure induces horizontal &
vertical loads that alter the normal
FORCES ON RETAINING WALLS
• Weight of soil above foundation base
• Earth pressure
• Surcharge i.e., forces due to loads on earth surface
• Soil reactions on footing
• Friction on footing due to sliding
• A concrete retaining
• An interlocking block
• A Wood retaining wall
• An Insulated Concrete
Form retaining wall or
ICF retaining wall
• The field of slope stability encompasses the analysis of static and dynamic
stability of slopes of earth and rock-fill dams, slopes of other types of
embankments, excavated slopes, and natural slopes in soil and soft rock.
SIMPLE SLOPE SLIP SECTION
SLOPE WITH ERODING RIVER & SWIMMING
• If the forces available to resist movement are
greater than the forces driving movement, the
slope is considered stable.
• Factor of safety=Forces resisting movement /Forces
• In earthquake-prone areas, the analysis is typically
run for static conditions and pseudo-static
conditions, where the seismic forces from an
earthquake are assumed to add static loads to the
• METHOD OF SLICES
• BISHOP’S METHOD
• SARMA METHOD
• LORIMER'S METHOD
METHOD OF SLICES
• Method for analysing the stability of a slope in two dimensions.
• The sliding mass above the failure surface is divided into a number of slices.
• The forces acting on each slice are obtained by considering the mechanical
equilibrium for the slices.
• Proposed by Alan W. Bishop.
• Method for calculating the stability of slopes.
• An extension of the Method of Slices.
• By making some simplifying assumptions, the problem becomes statically
determinate and suitable for hand calculations.
• Forces on the sides of each slice are horizontal
• The method has been shown to produce factor of safety values within a few
percent of the "correct" values.
• c’= effective cohesion
• ’= angle of internal friction
• b= width of slice
• w= weight of each slice
• u= water pressure at base of each slice
• Proposed by Sarawa K. Sarma
• A Limit equilibrium technique used to assess the stability of slopes under
• May also be used for static conditions if the value of the horizontal load is
taken as zero.
• Can analyse a wide range of slope failures as it may accommodate a multiwedge failure mechanism and therefore it is not restricted to planar or
circular failure surfaces.
• May provide information about the factor of safety or about the critical
acceleration required to cause collapse.
• Developed in the 1930s by Gerhardt
• A technique for evaluating slope stability
in cohesive soils.
• Differs from Bishop's Method in that it uses
a clothoid slip surface in place of a
• This mode of failure was determined
experimentally to account for effects of
A CLOTHOID OR EULER SPIRAL
• Also called Mechanically Stabilized
Earth or MSE.
• Soil constructed with artificial
• Can be used for retaining
walls, bridge abutments, dams, sea
walls, and dikes.
• MSE walls stabilize unstable slopes and retain the soil on steep slopes and
under crest loads.
• The wall face is often of precast, segmental blocks, panels or geocells that
can tolerate some differential movement.
• The walls are infilled with granular soil, with or without reinforcement, while
retaining the backfill soil.
• Reinforced walls utilize horizontal layers typically of geogrids.
• The reinforced soil mass, along with the facing, forms the wall.
• In many types of MSE’s, each vertical fascia row is inset, thereby providing
individual cells that can be infilled with topsoil and planted with vegetation
to create a green wall.
• Ease of installation.
• Quick construction.
• Do not require formwork or curing and each
layer is structurally sound as it is
laid, reducing the need for
support, scaffolding or cranes.
• Do not require additional work on the
• Retain sufficient flexibility to withstand large
deformations without loss of structural
integrity, and have high seismic load
• Polymeric products used to solve civil
• Includes eight main product categories:
geotextiles, geogrids, geonets, geomembranes,
liners, geofoam, geocells and geocomposites.
• Suitable for use in the ground where high levels
of durability are required.
• Can also be used in exposed applications.
• Available in a wide range of forms and
materials, each to suit a slightly different end
• Geosynthetic material used to reinforce soils.
• Used to reinforce retaining walls, as well as
subbases or subsoils below roads or structures.
• Soil pulls apart under tension. Compared to
soil, geogrids are strong in tension.
• Transfer forces to a larger area of soil.
• Made of polymer materials, such
as polyester, polyethylene or polyproylene.
• Woven or knitted from yarns, heat-welded from
strips of material, or produced by punching a
regular pattern of holes in sheets of
material, then stretched into a grid.
• Also called Cellular Confinement Systems.
• Used in construction for erosion
control, soil stabilization on flat ground and
steep slopes, channel protection, and
structural reinforcement for load support
and earth retention.
• Typically made with ultrasonicallywelded high-density polyethylene (HDPE)
or Novel Polymeric Alloy strips that are
• Creates a stiff mattress or slab to distribute
the load over a wider area.
• Reduces punching of soft soil.
• Increases shear resistance and bearing
• Decreases deformation.