Retaining Walls Lecture
Transcript of Retaining Walls Lecture
RETAINING WALLS
Retaining Walls Walls built to resist the pressure of liquids,
earth filling, sand or other granular materials filled behind it after it is built.
commonly required in the construction of hill roads, dams, abutments and wing walls of bridges.
Wall may be constructed of dry stone masonry, stone masonry,brick or concrete, depending on the type of material to be retained, site conditions and height of wall.
Design Principles Basically concerned with the lateral pressure of the retained
soil and any subsoil water.
Designed to ensure that Overturning does not occur Sliding does not occur Soil on which wall rests is not overloaded Materials used in construction is not overloaded.
Factors that can cause the collapse of retaining walls:
Presence of water at rear of retaining wall which adds to the pressure exerted by soil. Soil on which wall rests is overloaded Materials used in construction are overloaded. Unsuitability of design of retaining wall
Preventive measures that can be done:
Water at rear of retaining wall need to be removed efficiently. Proper design of retaining wall is important so as to ensure soil and materials used are not overloaded Avoid any earthworks done on site where earth is retained.
Types Of Retaining Walls
Mass Retaining Wall Cantilever Retaining Wall
Large toe Large heel
Counterfort Retaining Wall
Precast Retaining Wall
1.Mass Retaining Wall
Sometimes called gravity retaining wall Economic to height of 1.8 m Can be constructed of semi engineering bricks or mass
concrete Natural stone suitable for height up to 1 m high but
generally used as facing materials for walls 1 m high and above
Diagram of Mass Retaining Wall
2. Cantilever Retaining Wall
2 forms – Large heel - offers better resistance to overturning as
base is projecting partly in front and partly behind the wall.
large toe - design is adopted when it is not possible to excavate behind wall.
Usually of reinforced concrete and works on the
principle of leverage Has economic height range of 1.2 m to 6 m
Diagram of Cantilever Retaining Wall Large Heel Large Toe
3. Counterfort Retaining Wall (also known as Buttress Retaining Wall)
Can be constructed of reinforced and prestressed concrete
Suitable for walls of height over 4.5 m Counterforts are triangular beams placed at suitable
centres behind the stem and above the base Termed as buttress if the counterforts are placed in
front exposed to view
Diagram of Counterfort Retaining Wall.
4. Precast Retaining Wall
Manufactured from high grade precast concrete Erected as permanent retaining wall or free standing
to act as dividing wall Advantages
Reduction in construction time since curing period is eliminated
Costly formwork can be eliminated Time required to erect and dismantle formwork
can be eliminated
Diagram of Precast Retaining Wall1. Anda-Crib precast retaining wall
2. Marley precast retaining wall
Importance Of Drainage At Retaining Wall Necessary since water will
cause pressure at rear of wall Water will reduce strength of
soil Water will reduce frictional
force between base and soil thus reduces strength of wall
There are 2 methods of drainage
subsoil drain behind wall Weep holes in wall and
drainage channel at front of wall
Drainage At Retaining Wall
WEEP HOLES
WEEP HOLES
DRAINAGE CHANNEL
Drainage At Retaining Wall
Thank You Hope you have enjoyed the
lecture