A name truly cast in concrete
Prestressed Hollow-Core Walls RETAINING WALLS
SECURITY WALLS
ECHO PRESTRESSED HOLLOW-CORE RETAINING WALLING (EPRW®) THE CANTILEVERED
stand minor deferential settlement without
WALL SOLUTION
incurring structural damage.
This concept is a freestanding EPRW®
Gravity walling can be constructed in al-
with no lateral support at the top end of
most any situation where a rapid grade
the wall and no mechanical soil stabilisa-
change is desired. Gravity walling confines
tion. These walls cantilever loads to large
the soil or other fill material as a reinforc-
structural footings, converting horizontal
ing mass. This walling solution can also be
pressures from behind the wall to verti-
used in cut-and-fill applications.
cal pressures on the ground. The walls require rigid concrete heel-and-toe footings
INTRODUCTION A retaining wall is a structure designed and constructed to resist lateral soil pressure
which are cast below ground to resist the
GRAVITY WALL
overturning moment. This design limits
DESIGN CONSIDERATIONS
the height of the wall to 5,0m maximum. A gravity retaining wall must have sufficient weight and width to prevent ex-
THE GRAVITY WALL SOLUTION
ternal forces from overturning or shifting the wall. The wall must form an integral
when the desired change in ground elevaGravity retaining walls are constructed on
whole, ie, the individual slabs must func-
and with soil stabilised with man-made
tion as a single unit to create a wall suf-
Two basic design concepts – CANTILEVER
materials. This type of structure is able to
ficiently stable to handle the external
and GRAVITY - are used for the construc-
retain the earth behind it by virtue of its
forces that might cause it to collapse and
tion of Echo prestressed hollow-core retain-
weight. Gravity retaining walls have a de-
the internal forces that might cause it to
ing walls.
gree of flexibility that allows them to with-
lose shape.
tion exceeds the soil’s angle of repose.
01 | prestressed hollow-core walls
EXTERNAL STABILITY External stability of an EPRW® is achieved by designing to four potential external failure modes: • Global stability
: FSgl=1.5
• Base sliding
: FSsl=1.5
• Overturning
: FSot=2.0
• Bearing capacity
: FSbc=2.0
INTERNAL STABILITY Internal stability refers to the capacity of individual Echo prestressed hollow-core slabs forming a single integrated wall.
ADVANTAGES
The wall must be designed so that the individual slabs do not pull out, separate, or slide apart. This is achieved with either of the following options.
substantial
• Echo offers full turnkey retaining or se-
site labour. This wall solution is three
times faster than traditional in-situ
construction.
and reinforcing configurations can be
Grouted joints with key-formed
slab edges.
varied to suit wall height and load
Tongue-and-groove (T&G)
interlocking profiles.
Normative referee
• Openings for air conditioning ducts
SANS 207: 2011, Edition 1
and other services are easily accom-
•
Controlled factory production yields du-
The Echo Prestress retaining wall (EPRW®)
rable and aesthetically pleasing finishes.
concept, either on its own or in combina-
•
Panels can retain fill material up to 10m
tion with geogrid is as effective as more
as specified by the principal engineer.
walls; modular-block walls; or gabion basket walls.
SANS 10400-K: 2011, Edition 3 SANS 10400-H: 2012, Edition 3
modated.
walls; steel-reinforced concrete retaining
curity wall solutions.
requirements.
costly alternatives such as: cast in-situ
development
• Efficient light-weight sections. Depth
for
• Increased productivity and reduced on-
1) Echo’s standard edge profile:
2) Echo’s adapted edge profile:
land
purposes.
• Unlike retaining block walls, which are
constructed at an angle, prestressed
walls are 100% vertical, thus saving
SANS 10400-A: 2010 SANS 10400-B SANS 10400-H SANS 2001 – CC1:2007 Edition 1 BS 5896 BS 8002 BS EN 1897 BS EN 13738 SANS 1200 D SANS 2001 SANS 10100-1
Cores filled solid in the factory for 100mm
Wall heights up to 5,0m are possible with this design configuration. Add geotextile and heights of 6-7m walls are possible
SANS 10100-2 SANS 10162-1 SANS 10162-2.
Lifting hooks
Trowel finish this side
Fairface finish this side
Sub-soil drain to be built by specialist
Mo
me
Starter bars cast on site as per engineer’s design
nt
con
Grouting pockets at 200mm centres for pouring of nonshrink epoxy grout, SIKA 212 or similar approved by the principal engineer nec
tion
ach
iev ed
Foundation size according to principal engineer’s design
A TYPICAL SECTION THROUGH A VERTICAL HOLLOW-CORE RETAINING WALL
02 | prestressed hollow-core walls
HANDLING ORIENTATION
- VERTICAL A 10m high wall requires intermediate support Height of wall in m (meters)
250mm Echo wall panel
Water proofing by specialist
10.0 6.0 4.8 3.6 2.4 0
120 150 200 250 250 Wall slab depth in mm (millimeters)
ECHO PRESTRESSED HOLLOW-CORE SECURITY WALLS (EPSW®)
INTRODUCTION 150 mm
Echo security walls are not comparable
120 mm
Column flanges
with other walling products. In a class of their own, they protect high-value 120 mm Echo T&G wall
properties of strategic significance such as airports, military bases, industrial and
Fair face finish
commercial parks, mines and prisons – in fact any operation that requires over-
Wall panels are wedged and grouted into the column flange
the-top security. 50MPa concrete and prestressed steel on both sides of the
Steel column sizes are adapted to suit wall height, wind and soil conditions
Heights up to
walls. Handling orientation is horizontal and panel jointing is based on a tongueand-groove shear-key connection.
4.8 m possible
panels ensure robust and impregnable
Bolts to engineer’s specifications Base plate designed according to principal engineer 250 mm Echo solid precast base slab. Alternatavely a column base can be cast in-situ.
Natural ground level
Lifting hooks cast in base slab
50 mm river sand blinding
95% Mod AASHTO density
A TYPICAL SECTION THROUGH A HORIZONTAL HOLLOW-CORE SECURITY WALL
03 | prestressed hollow-core walls
ADVANTAGES
HANDLING ORIENTATION
• The soil quality - suitable for soil
1) This is the only precast concrete wall
conditions with a minimum 100KPa
constructed with 50MPa concrete and
bearing pressure.
reinforcing on both sides of the panels.
• Wall panels are typically 120mm or
Echo walls are virtually impregnable
150mm deep.
and cannot be scaled or broken without
• Wind resistance (Project specific).
generating considerable and detectable
• Water drainage weep holes supplied
disturbance.
by Echo.
• Typical centre-to-centre dimension
2) Speed
is 6.0m.
of
construction
beats
con-
ventional brick or in-situ methods.
• Wall accessories (razor wire; electric
wires, cameras etc).
3) Wall panels can be dismantled and re-
• Height specifications vary from 2,4m –
used because they are not grouted
4,8m with a 0,6m section below ground
but assembled with tongue-and-groove
for added security.
shear key joints instead.
04 | prestressed hollow-core walls
- HORIZONTAL
The support columns are based on a cantilevered design Height of wall in m (meters)
DESIGN CONSIDERATIONS
6.0 4.8 3.6 2.4 0
120 120 150 150 Wall slab depth in mm (millimeters)
Echo Prestress (Pty) Ltd
|
Part of the Echo Group of Companies
Hollow-Core Concrete Floors and Walls Cnr. Hytor & Chloor road, Chloorkop
|
Private Bag 1, Edleen, 1625
T: 011 589 8800
|
F: 011 589 8955
E: sales@echo.co.za
|
W: www.echo.co.za
GPS: 26 03 59.7 S 28 10 48.7 E
lasting value of choice
international prestressed Hollowcore association
Echo Prestressed reserves the right to alter any of the details contained herein without prior notice. Š Echo Prestress (Pty) Ltd 2014. Issue No1.