CONSTRUCTION
TECHNOLOGY &
maintenance
CEM 417
SOURCES FROM slide:
MOHD AMIZAN MOHAMD
MOHD FADZIL ARSHAD
SITI RASHIDAH MOHD NASIR
FKA, UiTM Shah Alam.
WEEK 2
Stages for construction
1.
2.
3.
4.
Building
Retaining walls, Drainage
Road, Highway, Bridges
Airports, Offshore/Marine structure
RETAINING
WALLS
WEEK 2
At the end of week 2 lectures, student will be
able to :
- Identify the different types of retaining
walls and their respective functions.
(CO1; CO3)
RETAINING WALL
function – to
retain soil at a slope
which is greater than it
would naturally assume,
usually at a vertical or
near vertical position
 Basic

Retaining wall failure at the Shin-Kang Dam
DESIGN OF RETAINING WALL



1.
2.
3.
4.
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:
Overturning of the wall does not occur
Forward sliding does not occur
Materials used are suitable
The subsoil is not overloaded
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


Failure of retaining wall (dam) due to water pressure..
TYPES OF WALLS
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Mass retaining walls
Cantilever walls
Counterfort retaining
walls
Precast concrete
retaining walls
Precast concrete cribretaining walls
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 semiengineering 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

TYPICAL EXAMPLE OF MASS RETAINING
WALLS
BRICK MASS RETAINING WALL
Brick retaining
wall
Stone retaining wall
TYPICAL EXAMPLE OF MASS RETAINING
WALLS
MASS CONCRETE RETAINING WALL WITH
STONE FACINGS
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 prestressing techniques
 Any durable facing material can be applied to the
surface to improve appearance of the wall

Cantilever wall

Two basic forms:A base with a large heel
 A cantilever with a large toe

Cantilever T
Cantilever L
CANTILEVER WALLS
COUNTERFORT RETAINING WALLS
Can be constructed of reinforced or prestressed
concrete
 Suitable for over 4.5 m
 Triangular beams placed at suitable centres
behind the stem and above the base to enable the
stem and base to act as slab spanning
horizontally over or under the counterforts

PRECAST CONCRETE RETAINING WALL



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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
APPLICATION
PRECAST CONCRETE RETAINING WALLS
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.

SUBSOIL
DRAINAGE
At the end of week this lecture, student
will be able to :
- Identify the functions of various
subsoil drainage system. (CO1; CO3)
DRAINAGE
Effluent- can be defined as that which flows out. In
building drainage terms, there are three main forms of
effluent:
1. Subsoil water – water collected by means of
special drains from the earth primarily to lower
the water table level I the subsoil –clean, no need
to treat.
2. Surface water –effluent collected from the
surfaces such as roofs, paved areas- clean
3. Foul or soil water –effluent contaminated by
domestic or trade waste and require treatment
SOURCE OF WATER
BUILDING REGULATION C2
-RESISTANCE TO MOISTURE
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Subsoil drainage shall be provided if it is needed to avoid:
The passage of ground moisture to the interior of the
building

Damage to the fabric of the building
Needed for sites with a high water table (level at which
water occurs naturally below the ground)
Objective of subsoil drainage – to lower the water table to a
level such that it will not rise to within 0.25 m of the lowest
floor of a building
Advantages – improve the stability of the ground, lowering
the humidity of the site and improve its horticultural
properties

The water collected by a subsoil drainage system
has to be conveyed to a suitable outfall such as a
river , lake or surface water drain and sewer.
THE IDEAL SITE
TYPICAL SUBSOIL DRAINAGE DETAILS
MATERIALS OF SUBSOIL DRAINAGE
Porous - absorb water through their walls and thus keep
out fine particles of soil or silt
 Perforated – Holes in pipe of different pattern which
allow water to enter into the pipe and channels to a
collection points and discharged into the designated
outlet.

SUITABLE PIPES
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Perforated clayware – BS EN 295-5
Porous concrete – BS 5911:part 114
Clayware field pipes – BS 1196
Profiled and slotted polypropylene or uPVC –
BS 4962
Perforated uPVC – BS 4660
POLYETHYLENE PIPE
PERFORATED PIPE
Perforated pipes for footing drains
& ABS pipe for downspout drains
Subsoil drainage
SUBSOIL DRAINAGE SYSTEMS

The layout of subsoils drains will
depend on whether it is necessary to
drain the whole site or if it is only
the substructure of the building
which needs to be protected
MODEL OF SUBSOIL DRAINAGE
Subsoil drainage systems and drains


The pipes are arranged in a pattern to cover as much of the site as is
necessary
Water will naturally flow towards the easy passage provided by the drainage
runs
HERRINGBONE DRAINAGE
MOAT DRAINAGE
OUTFALL TO STREAM OR RIVER
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
The system is terminated at a suitable outfall such as a river, stream or surface
water sewer
In cases, permission must be obtained before discharging a subsoil system