BY GASHAW HAILE (LECTURER AT WOLKITE UNIVERSISTY)

1. CHAPTER 3
LATERAL EARTH PRESSURE
Gashaw H.(wku2022) 1

2. What Is a Retaining Wall?
Retaining walls are rigid wall structures that supporting soil
laterally help so that it can maintain the surface of the ground at
different elevations on either side of the structure. If there is no
retaining wall support, the soil at a higher elevation would tend to
move down till it acquires its natural, stable configuration.
Consequently, the soil that is now retained at a steeper slope than it can
sustain by virtue of its shear strength exerts a force on the retaining wall.
Retaining Walls are broadly classified as follows
1. Gravity Retaining Wall
2. Cantilever Retaining Wall
3. Counterfort Retaining Wall
4. Buttress Retaining Wall
5. Crib Retaining Wall
6. Gabion Retaining Wall
7. Sheet Pile Retaining Wall
8. Anchored Earth Retaining Wall
9. Diaphragm Retaining Wall
10. Reinforced Retaining Earth Wall
3.1.1 Retaining walls
Gashaw H.(wku2022) 2

3. 1. Gravity Retaining Wall
Gravity Retaining wall assures its stability by its own weight. These
walls are majorly designed to eliminate the overturning effect of
the lateral earth pressure and do not induce tensile stresses within
the section.
Gravity retaining walls are suitable for the low height and are not
economical for large heights. It can be made from stone, bricks,
mass concrete, and precast concrete blocks.
Gashaw H.(wku2022) 3

4. 2. Cantilever Retaining Wall
Its section is of trapezoidal shape with a base width
between 0.3 and 0.5 H, where H is the height of the
wall and the top width is between 0.2m to 0.3m.
In the case of a concrete gravity retaining wall, a top
width of 0.3 m is recommended for the proper
placement of concrete.
Gashaw H.(wku2022) 4

5. Reinforced concrete cantilever types of retaining wall are
recommended for heights up to 7 m. This type of wall has a
vertical stem monolithic with the base.
A slender section can be used in this retaining wall the tensile
stresses within the stem and the base is resisted by steel
reinforcement.
3. Counterfort Retaining Wall
Counterfort retaining walls are used for height more than 6m. Its stem
provided act as slab spanning between the counterfort supports. The
distance between support is about 2/3 H but should not be less than 2.5 m.
Gashaw H.(wku2022) 5

6. 4. Buttress Retaining Wall
A buttress wall is a form of counterfort wall. These types of retaining walls
are built on the face of the wall and not within the backfill. Buttress walls
are not too popular because of their buttressed shape exposed outside
which consumes space and spoils the appearance.
Gashaw H.(wku2022) 6

7. 5. Crib Retaining Wall
The crib wall is shown in the figure. Crib walls consist of a series of boxes
made from timber, precast concrete, or steel members, which are filled with
granular soils. It acts as a gravity wall with the advantage of a quick
erection.
Crib walls can withstand large displacement of soil due to its flexible nature. It
is usually fitted so that its face has a batter of 1 in 6. The width of the wall varies
from 0.5 to 1.0 H and is suitable for walls up to a height of about 7.0 m. Note that
the crib wall should not be subjected to surcharge loadings.
Gashaw H.(wku2022) 7

8. 6. Gabion Retaining Wall
These retaining walls are constructed from rectangular metal cages or
baskets. A gabion wall is made from a square grid of steel fabric,
generally, 5 mm in diameter and spaced 75 mm apart.
The gabion baskets are usually 2 m long and 1 m in cross-section. Each
basket is provided with center diaphragm divides into two equal 1 m 1 m
sections and adds stability.
At the time of making stone-filled baskets are secured together with steel
wire of 2.5 mm diameter. The base width of the gabion wall is about 0.5H.
A typical wall is shown in the figure. A good-looking face can be provided
by slightly stepping back each succeeding layer.
Gashaw H.(wku2022) 8

9. 7. Sheet Pile Retaining Wall
Sheet pile retaining walls are constructed from a series of interlocking
piles individually driven into the foundation soil. Nowadays, modern sheet
piles are constructed from steel, timber, or precast concrete sections are
also used.
Sometimes, a Cantilever sheet pile walls are held in the ground by the
active and passive pressures that act on its lower part.
Gashaw H.(wku2022) 9

10. 8. Anchored Earth Retaining Wall
These types of retaining walls are fixed at the base and
are supported by a row or two rows of ties or struts
placed near its top.
Gashaw H.(wku2022) 10

11. 9. Diaphragm Retaining Wall
Diaphragm walls can be of a reinforced concrete wall or sheet pile
wall. It includes a vertical concrete reinforced concrete slab fixed in
position. Wall is held in position by the passive and active pressures
acting on its lower portion.
What is a diaphragm wall used for?
Diaphragm walls are underground structural elements commonly
used as retention systems and permanent foundation walls. They
can also be used as groundwater barriers.
Gashaw H.(wku2022) 11

12. 10. Reinforced Earth Retaining Wall
In this retaining wall, the use of reinforcement to strengthen the soil has
been known for centuries. In the past straws are used to strengthen
unburnt bricks and fascine mattresses have been used to strengthen soft
soil deposits prior to road construction.
The main phenomenon working in reinforced earth walls is that a mass of
soil can be given tensile strength in a specific direction if the lengths of a
material capable of carrying tension are embedded within it in the required
direction. Reinforced earth has been used in many geotechnical
applications.
Gashaw H.(wku2022) 12

13. Gashaw H.(wku2022) 13

14. Gashaw H.(wku2022) 14

15. 3.2 Earth pressure theories
Ko=1-sinФ’ ====> At rest earth pressure coeff.
Ka=
1−𝑠𝑖𝑛ϕ′
1+𝑠𝑖𝑛ϕ′
==⇒ 𝐴𝑐𝑡𝑖𝑣𝑒 𝑒𝑎𝑟𝑡ℎ 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑐𝑜𝑒𝑓𝑓. . (𝑓𝑜𝑟 ℎ𝑜𝑟𝑖𝑧. 𝑏𝑎𝑐𝑘 𝑓𝑖𝑙𝑙)
Kp=
1+𝑠𝑖𝑛ϕ′
1−𝑠𝑖𝑛ϕ′
==⇒ 𝑃𝑎𝑠𝑠𝑖𝑣𝑒 𝑒𝑎𝑟𝑡ℎ 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑐𝑜𝑒𝑓𝑓. . (𝑓𝑜𝑟 ℎ𝑜𝑟𝑖𝑧. 𝑏𝑎𝑐𝑘 𝑓𝑖𝑙𝑙)
3.1.4 E𝑎𝑟𝑡ℎ 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡𝑠.
Gashaw H.(wku2022) 15

16. Rankine’s Active earth pressure for horizontal back fill ground
 Granular material
Gashaw H.(wku2022) 16

17. Gashaw H.(wku2022) 17

18. Gashaw H.(wku2022) 18

19.  Rankine’s Active earth pressure for horizontal back fill
 Cohesive material
 Tension cracks and unsupported excavation
Gashaw H.(wku2022) 19

20. Gashaw H.(wku2022) 20

21. Gashaw H.(wku2022) 21

22. Gashaw H.(wku2022) 22

23. Earth pressure for Inclined back fill
Rankine’s
Coulomb’s
Gashaw H.(wku2022) 23

24.  Rankine’s Active earth pressure for Inclined back fill
Gashaw H.(wku2022) 24

25.  Coulomb’s Active earth pressure for Inclined back fill
Gashaw H.(wku2022) 25

26. Gashaw H.(wku2022) 26

27. Gashaw H.(wku2022) 27
B

28.  PROCEDURE
Gashaw H.(wku2022) 28

29. Gashaw H.(wku2022) 29

30. Gashaw H.(wku2022) 30

31. Gashaw H.(wku2022) 31

32. Gashaw H.(wku2022) 32

33. Gashaw H.(wku2022) 33

34. THANK YOU
Gashaw H.(wku2022) 34