Earth retaining structures are used to support soil and structures where there are differences in ground elevation. There are two main types: gravity walls, which rely on their own weight for stability, and embedded walls, which rely on passive earth pressure and anchors. Gravity walls include mass concrete walls, reinforced concrete cantilever walls, counterfort walls, crib walls, and gabion walls. Cantilever walls are the most common reinforced concrete wall for heights up to 7 meters. Counterfort walls provide greater stability for taller walls over 7 meters. Embedded walls include sheet pile walls made of steel, timber, or concrete, and diaphragm walls which are reinforced concrete walls installed like sheet pile walls.

1. Earth Retaining Structures

2. Why we need earth retaining structures
• to support the soil and structures to maintain a difference in
elevation of the ground surface

3. Earth Retaining
Structures
Gravity Walls
(Relying on gravity
for stability)
Embedded Walls
(Relying on passive earth pressure
and anchors for stability)

4. Gravity Walls
• Mass construction gravity walls
• Reinforced concrete walls
Cantilever Wall
Counter front Wall
• Cribs Wall
• Gabion Wall

5. Mass construction gravity wall
• built in mass concrete or cemented precast concrete blocks,
bricks, stone, etc.
• depends on its weight for the stability.
• Generally used for low walls and become uneconomical for
high walls

7. Reinforced Concrete walls
Cantilever Walls
• Has a vertical, or inclined, stem monolithic with a base
• Suitable for heights up to about 7 m
• Slenderness is possible as the
tensile stresses within its stem
and base are resisted by steel
reinforcement
• Most common type of walls due
to economy and ease of
construction
.

9. Counter Front Walls
• For larger heights (> 7m), cantilever walls may not be
economical as large bending moments are developed at
the base of the stem.
• Economy can be achieved by providing counterforts walls.
• Counterforts act as tension stiffeners & connect wall slab and
base to reduce bending moment and shearing stresses

10. • Can be used for heights greater than 6 m
• Counterforts space -0.6H but not less than 2.5 m due to the
construction considerations.
• The footer, counterfort and retaining wall should be tied to
one another with steel r/f

11. Buttressed Wall
• where counterforts are built on the face of the
wall (not in the back fill).
• Buttresses add incredible strength to the wall
system.
• Economical foe heights greater than 7m.
• Situations which demand this type
of wall usually have tremendous
loads which bear against the walls.
• Buttress may be useful but, due to
the exposed buttresses - can
become unsightly & not very
popular

13. Approximate dimensions for various
components

15. Cribb Walls
• Consist of series of pens (prefabricated
timber, precast
concrete or steel members) which are
filled with granular soil.
• Advantages - quick erection and, can
bear large differential
settlements (due to its flexible nature).
• Width - 0.5H to 1.0H ; Height - up to
about 6.5 m

17. Gabion Walls
• It is a cuboid metal cages or baskets made up from a square
grid of steel fabric ( 5 mm in dia. & spacing - 75 mm)
• These baskets - 2 m long & 1 m2 in cross section
• A central diaphragm - divides it into two equal 1 m3 sections &
adds stability.
• Base - about 0.5H

19. • suitable for gravity walls where rock fill
material are available
• Applications - erosion protection of banks
of rivers, retaining
walls along roads and highways, etc

20. Failure modes for gravity retaining walls
1. Gravity Retaining walls

22. Embedded Walls
• Rely on the passive resistance of the soil in front of the lower part of
the wall to provide the stability
• Anchors or props, if incorporated, provides additional support

23. • fail by either deep-seated failure, rotation at the base, rotation about
the anchor or prop, failure of the anchor, bending of the wall, or
seepage induced failure

24. Sheet Pile Walls
• Constructed to retain earth, water or any other fill material;
thinner in section.
• Most of the modern sheet pile walls are made of steel (but timber
or precast concrete sections also in use)

25. Diaphragm Walls
• Can be classed either as a reinforced concrete wall or as a sheet
pile wall .
• It consists of a vertical r/f concrete slab fixed in position in the
same manner as a sheet pile in that the lower section is held in
place by the active & passive earth pressure

27. Thank You !