Retaining wall, earth retaining structure, function, active earth pressure , passive earth pressure, types of wall and design consideration. #Puneet chhonker Mo.7455006961

1. ASSIGNMENT - 14
BUILDING CONST. IV
TOPIC : RETANING WALL
SUBMITTED BY:SUBMITTED TO:
->PUNEET CHHONKER
->B.ARCH 3rd YR , 5th SEM.
-> Ar. SURJEET SINGH

2. CONTENT
SR.NO. TITLE.
1. Retainingwall:
2. EARTH RETAINING STRUCTUR
3. FUNCTION
4. ACTIVE EARTH PRESSURE
5. PASSIVE EARTH PRESSURE
6. Design consideration
7. Factors which designer need to take account
8. Types of walls
9. Mass retaining walls
10. Cantilever Walls
11. Counterfort Retaining Walls:
12. Precast concrete retaining wall:

3. Retainingwall:
Retaining walls are structure used to retain soil, rock or other materials in a vertical condition.
Hence they provide a lateral support to vertical slopes of soil that would otherwise collapse into a more
natural shape.
Most common materials used for retaining walls are:
- Wood sheets;
- Steel and plastic interlocking sheets;
- Reinforced concrete sheets;
- Precast concrete elements (crib walls and block walls);
- Closely spaced in-situ soil-cement piles;
-- Wire-mesh boxes (gabions);
- Anchors into the soil or rock mass (soil nailing).
• Earth retaining structure can be classified to 2 types:
A) Externally Stabilized Systems
i) In- Situ Walls
ii) Gravity Walls
B) Internally Stabilized Systems
i) Reinforced Soils
ii) In-Site Reinforcement
EARTH RETAINING STRUCTURE
FUNCTION
To retain the soil at a slope that is greater than it would naturally assume, usually at a vertical or near
vertical position.
It is a structure that holds back soil from a building or structure. Retaining walls prevent down slope
movement and provide support for vertical or near- vertical grade changes. Concrete retaining
walls can serve aesthetic and landscape design functions as well.

4. The effect of 2 forms of earth pressure need to be considered during the process of
designing the retaining wall that is:
a) Active Earth Pressure
“ It is the pressure that at all times are tending to move or overturn the retainingwall”
a) Passive Earth Pressure
“It is reactionary pressures that will react in
the form of a resistance to movement of the wall.
ACTIVE EARTH PRESSURE
It is composed of the earth wedge being retained together with any hydrostatic pressure
causedby the presence of groundwater.
This pressure can be reduced by:
i) The use of subsoil drainage behind thewall
ii) Inserting drainage openings called weep holes through the thickness of the stem to enable
the water to drain away.
PASSIVE EARTH PRESSURE
• This pressure build up in front of the toe to resist the movement of the wall if it tries
to move forward.
• This pressure can be increased by enlargingthe depth of the toe or by forming a rib on the
underside of the base.
EFFECT

5. Retaining walls are structures constructed for the purpose of
retaining earth or other materials like coal, ore, water etc.
• It may also be defined as a wall provided to maintain
ground at two
different levels. Provisions of retaining walls become
necessary in the
construction of hill roads, embankments, bridge
abutment, basement in
buildings, water reservoir, in preventive measures
against soil erosion, in
landscaping etc.
•The material retained by the wall is generally known as backfill. The backfill
may be horizontal i.e., levelled with the top of wall or it may be inclined at
certain angle to the top.
•The inclined fill is also known as surcharge. Besides loads due to retained
material, the retaining wall may also be subjected to surcharged load (due
to automobile, rail road etc.) acting directly on the wall as well as on the
backfill.
•The retaining wall should be stable enough to resist all type of forces acting
on it.
Retaining walls have primary function of retaining soils at an angle
in excess of the soil’s nature angle of repose.
Walls within the design height range are designed to provide the
necessary resistance by either their own mass or by the principles of
leverage.
Design consideration:
1. Overturning of the wall does not occur
2. Forward sliding does not occur
3. Materials used are suitable
4. The subsoil is not overloaded

6. • Back fill: The soil placed behind a wall.
• Back fill slope: Often the back fill slopes upward from the back face of the wall. The
slope is usually expressed as a ratio of horizontal to vertical (e.g. 2:1).
• Footing (or foundation): That part of the structure below the stem that supports and
transmits vertical and horizontal forces into the soil below.
• Grade: The surface of the soil or paving; can refer to either side of the wall.
• Heel: That portion of the footing extending
behind the wall (under the retained soil).
• Retained height: The height of the earth to be
retained, generally measured upward from the
top of the footing.
• Stem: The vertical wall above the foundation.
• Surcharge: Any load placed in or on top of the
soil, either in front or behind the wall.
• Toe: That portion of footing which extends in
front of the front face of the stem (away from
the retained earth).
• Weep holes: Holes provided at the base of the
stem for drainage. Weep holes usually have
gravel or crushed rock behind the openings to
act as a sieve and prevent clogging. Poor
drainage of weep holes is the result of weep
holes becoming clogged with weeds, thereby
increasing the lateral pressure against the wall

8. Factors which designer need to take account:
• Nature and characteristics of the subsoil's
• Height of water table – the presence of
Water can create.
hydrostatic pressure, affect bearing
capacity of the subsoil
together with its shear strength, reduce
the frictional
resistance between the underside of the
foundation
• Type of wall
• Materials to be used in the construction
Types of walls:
• Mass retaining walls
• Cantilever walls
• Counterfort retaining walls
• Precast concrete retaining walls
• Precast concrete crib-retaining walls

9. Mass retaining walls:
• Sometimes called gravity walls and rely upon their own mass together with the friction on the
underside of the base to overcome the tendency to slide or overturn
• Generally only economic up to 1.8 m
• Mass walls can be constructed of semi-engineering quality bricks bedded in a 1:3 cement mortar or of
mass concrete
• Natural stone is suitable for small walls up to 1m high but generally it is used as a facing material for
walls over 1 m.
• The wall is so proportioned that the dead weight of the wall provides required stability against the
thrust exerted by the backfill including surcharge.
BRICK MASS RETAINING WALL
MASS CONCRETE RETAINING WALLWITH STONE FACINGS

10. Cantilever Walls:
• Usually of reinforced concrete and work on the principle of
leverage where the stem is designed as a cantilever fixed at the
base and the base is designed as a cantilever fixed at the stem
• Economic height range of 1.2 m to 6 m using pre-stressing
techniques
• Any durable facing material can be applied to the surface to
improve appearance of the wall.
TWO BASIC FORMS:
• A base with a large heel
• A cantilever with a large toe
CANTILEVER T
CANTILEVER L

11. Counterfort Retaining Walls:
• Can be constructed of reinforced or Prestressed concrete
• Suitable for over 4.5 m
• In this type of wall the base slab as well as the stem of the wall
span horizontally as continuous slabs between vertical brackets
known as counterforts.
• The counterforts are provided behind the wall (on the backfill
side) and are subjected to tensile forces. The spacing of the
counterforts may vary from of the height of wall. The more the
height of the wall, the closer should be the spacing of
counterforts
Precast concrete retaining wall:
• Manufactured from high-grade pre cast concrete on the cantilever principle.
• Can be erected on a foundation as permanent retaining wall or be free
standing to act as dividing wall between heaped materials which it can increase
three times the storage volume for any given area
• Other advantages- reduction in time by eliminating curing period, cost of
formwork, time to erect and dismantle the temporary forms
• Lifting holes are provided which can be utilized for fixing
if required

12. Pre cast concrete crib-retaining walls:
• Designed on the principle of mass retaining walls
• A system of pre cast concrete or treated timber components
comprising headers and stretchers which interlock to form a 3
dimensional framework or crib of pre cast concrete timber units
within which soil is retained
• Constructed with a face batter between 1:6 and 1:8
• Subsoil drainage is not required since the open face provides
adequate drainage.
~Puneet Chhonker