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Local News and Developments from AMT
THE ENTRANCE - NSW
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Platipus anchors have been used in remediation
of part of The Entrance sea wall. The work was commissioned
by Council to prevent further deterioration in the wall. Sixty-two
type BO8TC galvanised anchors were used on the project with
a driven depth of 9m.
The loads achieved were variable due to the poor condition of
the soil and other aspects of the site. The area immediately
adjacent to where work was undertaken had previously been the
old roadway and site of the original retaining wall restraints
and other old construction work. In addition to encountering
poor soil at various parts of the works, the installers also
experienced difficulty with voids in the soil and buried objects,
old construction debris, etc. Nevertheless, despite these difficulties,
nearly all anchors still achieved their designed ultimate point
load of 160kN and where they did not extra anchors were able
to be immediately installed.
A particularly challenging aspect of the project was the
need to install the anchors without putting any additional
load on the wall that would precipitate its collapse. The
use of a barge to carry the installation equipment was considered
but was problematic due to the considerable variation of the
water depth at the work site as a result of tides (when the
tide was out the sea floor would be exposed, when it was in
the water would be one to two metres deep). The cost of using
a barge would also have greatly increased installation costs.
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The picture above shows the process used. The excavator has an extended
arm that allows it to drive the anchors "backwards" through
holes cut in the capping beam of the wall and into the earth behind
it. Note the steel "trestle" sections used to distribute the
weight of the excavator across the width of the promenade. As the excavator
moved along the wall, these steel sections were moved from behind as
it passed by and placed in front of the machine. A portable scaffolding
system was set up for the installer to stand on and direct the excavator
operator. In the picture the installer is aligning the moil of the excavator
with the drive rod shank so that the anchor can be hammered into position.
From this vantage point the installer could also monitor and adjust
both the drive rod and anchor rod during installation.
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The picture below provides another, perhaps clearer, view
of the excavator set-up and the trestle used to distribute
its weight.
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Another advantage of the Platipus system for this project
was the ability to proof load each anchor immediately upon
installation.
The picture at left shows the installers checking the in-line
load cell readings as the anchors are being stressed (the
stressing jack can be seen sitting on the sea wall at the
lower right hand corner of the picture).
Given the wide variation in soil conditions it was imperative
that the precise load achieved at each anchor point be determined.
Any shortfall in meeting the required load could then be immediately
remedied by installation of an additional anchor at an appropriate
position on the wall.
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WOLLONGONG NSW
Platipus anchors were used to anchor sheetpile at the Wollongong Sewerage Treatment Plant, which is being
upgraded as part of the Illawarra wastewater strategy works. AMT was approached after conventional grouted
strand anchors failed during the installation phase. 64 type BO8TC anchors were used to achieve loads of between
140kN to 260kN in very difficult soil conditions, including highly saturated soil and compacted fill.
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Anchor Testing at Wollongong Sewerage Treatment Plant.
Two anchors were site tested prior to work being undertaken. The picture above shows the type BO6TC anchor being
driven into a depth of 8 metres. This anchor achieved a load of 180kN at this location (see picture). The other
test anchor, a BO8TC, achieved 200kN in saturated sandy/clayey soil.
Site testing is not invariably essential. At times a geotechnical report interpreted by someone experienced with
our anchors will suffice to make a reasonable estimate of the types of loads that the anchors will achieve on a
site. However, soil conditions on this site were highly variable including areas that were almost waterlogged
and areas where the previous use of the site as a dump meant there was uncertainty as to the composition of the
soil. In these circumstances a site test of the anchors is strongly recommended.
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At left is a view of the first phase of installation.
An attempt had been made earlier to install 3 conventional grouted strand anchors but this had failed. Platipus
anchors were then used because of their speed of installation and their ability to immediately be proof loaded
and carry loads.
Potential liquidated damages were a concern for the builders when
Platipus installers commenced work. Being able to quickly tell
precisely what load the anchors were holding proved a definite
advantage in retrieving the situation. Directly after installation
the anchors were proof loaded and it was immediately obvious where
additional anchor points would be necessary to achieve the designer’s
required loading. It was then a simple matter to position any
additional anchors accordingly. The picture below shows installers
stressing the anchors and checking loads achieved on the in-line
load cell.
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Despite the very poor soil conditions on site, many BO8TC type anchors still achieved loads of 240kN to 260KN at
7 to 8 metres installation depth. High tensile steel rods were used in these anchor systems to enable them to
carry those loads.
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DEE WHY, NSW
310 Platipus anchors were used on this project to anchor contiguous piles
prior to excavation for the building of a shopping arcade/office complex.
Soil at the site was coarse and granular (typical beach type soil) which,
as can be seen from the picture, was sometimes very wet.
The picture below shows anchors being stressed and loads checked by a
representative of the client.
The picture at left shows the piling supported by Platipus anchors with the load distributed across a waler.
Excavation started almost immediately the last anchor was competed.
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CANBERRA ACT
ActewAGL has been in the process of introducing Platipus anchors to its low voltage line pole staying
operations for some time now. They are convinced that using Platipus anchors offers them greater flexibility
and cost-effectiveness.
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Pole staying using conventional methods often requires the use of large concrete blocks usually buried at some
distance from the pole. In a training course for ActewAGL employees, pictured at left, a 2 tonne concrete block
has been set on a steel skid, with spikes digging into the soil, and is connected to support a steel high
voltage terminal pole.
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Pictured at left, a Platipus type BO6TC anchor was installed with six metres of M20 steel rod. Then, pictured
below, the load was transferred from the block to the Platipus anchor. This BO6 anchor at 339mm long, 206mm
wide, 91mm high and weighing less than 5kg replaced the 2 tonne block of concrete without any problem.
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Two major advantages were immediately apparent to ActewAGL:
1. The anchors are light and very portable. They can be easily moved from site to site together with the
installation equipment; and
2. There is no need to dig holes, pour concrete and wait for it to cure before the pole can be supported. The
whole operation takes about 20 minutes, from start to finish.
These advantages represent significant savings for ActewAGL. In comprehensive testing, materials and labour
costs dropped to almost half of the cost that they were previously incurring using traditional anchoring
methods.
ActewAGL were equally pleased with improvements they could make to their services and interaction with clients
by using Platipus anchors. The stays are quickly installed meaning minimal disruption to clients and public.
Also they can be installed in places where space constraints meant they could not be placed previously,
facilitating wider service provision and placement of stays in positions of optimal convenience to clients.
To the left, the anchors are being installed straight through gravel and road fill. The small excavator being used to
drive the anchor into position represents little disruption to the business operation at left and the machine
was there and gone in 30 minutes.
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The stay pictured, above-left is both situated close to the fence and has not disturbed the garden soil,
impossible to achieve using conventional systems. As a result, clients are not losing large parts of their
back yards or other living space to accommodate cumbersome anchor systems. So, as well as being in and out of
their living space quickly, ActewAGL is not ruining their living environment. Pictured at
above-right, an
anchor is being installed on the verge of parkland. Notice the minimal impact installation is having on the
trees and shrubbery.
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NARRABEEN , NSW
Builders at this site ran into trouble when the sheet piling they had installed started to collapse on
commencement of excavation work.
Platipus anchors were called for as a matter of urgency. Holes were cut in the sheet pile so that anchor heads
could be put through. The anchors were then driven into the ground using a hand-held breaker. Short lengths of
waler were used to hold back the sheet pile and distribute the load. The piling was secured and work resumed in
quick time. No one was injured.
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BRISBANE, QLD
These semi-mature trees were transplanted into the Queen St Mall. Platipus RF2 rootball fixing kits were used to
tie down the rootball of the trees to support them. The lack of guy wires in this system makes the trees more
appealing to the eye. It also removes the risk of pedestrians, in crowded places such as this, tripping over guy
wires or extruding stays and, amongst other things, taking legal action to seek compensation.
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TOONGABBIE, NSW
The road pictured at left required support for the embankment and a guard rail. Platipus BO8 type anchors were
used. Note the position of the excavator that is driving the anchors into the ground. The ability to work with
the anchors on sites where access is difficult is a feature of Platipus anchors and there are many ways in which
users can take advantage of this.
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At left, another section of the wall is shown. Following installation of the anchors, the decorative block wall
could be erected by simply interlocking the blocks, as it only had its own weight to support.
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Shown below is the installer proof loading the anchors.
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