The Stewart Drilling Ground Anchoring System offers a unique and versatile tool for designers and builders who are attempting to find solutions for the temporary or permanent stabilisation of natural or man made structures.
The ground anchor can be installed in virtually any type of ground to provide large concentrated forces at precise locations. They can be installed in drill holes at any angle of inclination and can be a monitored and restressed at any time.
The ground anchor transfers forces into the ground by means of a steel tendon inserted into a borehole and grouted to the surrounding material. The tendon is constructed from a number of 12.7mm or 15.2mm diameter super grade high tensile steel strands. The number of strands used is varied to suit the required anchor capacity.
| Ground
anchors can be generally categorised as soil anchors or rock anchors
although the principle of operation is the same. Stewart Drilling
Contractors Pty. Ltd. offer a range of permanent and temporary ground
anchors to suit most applications.
Soil anchors are pressure grouted anchors installed in alluvial material, soil, clays, loose or highly weathered rock. Rock anchors are similar in detail to soil anchors but with at least all the bond length located in rock. The ultimate capacity of all ground anchors is a function of the ability of the ground to accept the transfer of load from the tendon, the number of strands in the tendon and the length of the bond zone. Stewart Dilling is a fully Australian owned company which has been involved in ground and structure stabilisation for over thirty years. Using
the experience gained over this period, Stewart Drilling has designed and developed a ground anchoring system eminently suitable
for Australian conditions. All components are of Australian design
and manufacture. |
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Support of Excavations
| Many excavations require support structures and/or the stabilisation of the excavation face. The use of ground anchors in lieu of the heavy internal shoring of sheet piling, lagging, drilled piles and diaphragm walls provides unrestricted excavation areas with the consequent cost savings. |  |
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Retaining Walls
With
the increasing requirement for maximum site utilisation the demand
for restraining walls has increased. The integration of Stewart Drilling
Ground Anchoring System into the retaining wall offers the Design
and Construction Engineer a versatile tool that provides a practical
and economical solution.
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Ground Stabilisation
Any
excavated face may require stabilisation due to weathering or the
geology of the ground. The use of Stewart Drilling Ground Anchors,
by themselves or with additional treatment of the excavated face,
provides a perminent solution to stability problems. Stewart Drilling
Ground Anchor is ideally suited for the stabilisation of Railway or
Road cuttings, basements of buildings and to provide local support
fro underground excavations and mines.
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Stabilisation for uplift
Considerable
uplift forces may be experienced by boat-like structures that are
situated below the ground water level. The use of Stewart Drilling
Ground Anchors proved an efficient and cost efefctive solution to
this problem.
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Stabilisation of structures
The
stability of structures such as bridges, dams and large retaining
walls can be increased by Stewart Drilling Ground Anchors to assist
gravitational forces or counteract eccentrically loaded foundations.
The Stewart Drilling Ground Anchor can be used to transfer external
tensile forces to the ground and is suitable for securing guy wired
for towers, suspension bridges etc.
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Pile Load Test
The
testing of pile performance is now a simple matter of loading the
pile against a suitable beam held down by Stewart Drilling Ground
Anchors placed adjacent to the beam. This method is particularly suitable
for the testing of the larger capacity piles that can be constructed
by modern piling equipment.
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About Anchor Types
The Stewart
Drilling Anchor System is available in either temporary or permanent form.
the type of ground anchor used is dependant upon the particular application.
Where the long term stability of structures relies upon the performance
of the ground anchor it is necessary to use the Stewart Drilling Permanent
Ground Anchor. The design and fabrication of the Stewart Drilling Permanent
Ground Anchor provides maximum corrosion protection and ensures resistance
to deterioration for the planned life of the structure.
The Stewart Drilling Temporary Ground Anchor has a service life of up to
2 years and is suitable for the support of construction elements that do
not form part of the final structure. It is ideally suited inproviding temporary
support for all types of shoring and basement walls.
Temporary Anchor
The
Stewart Drilling Temporary Ground Anchor consists of a tendon of a
single or bundled strands. The strand can be either 12.7mm or 15.2mm
diameter supergrade high tensile steel. The number of strands per
tendon is dependant upon the required capacity of the anchor.
The Strand in the bond length is shaped length is shaped to achieve
maximum grout bond. A polythylene tube is installed over the greased
strand in the free length to provide simple corrosion protection protection.
The tendon is then placed in the drilled hole and bonded to the soil/rock
using high strength grout.
The method of drilling the hole is governed by the nature of the ground
conditions and will vary from drill and case in the alluvium to rotary
percussion in rock.
The bearing plate and anchor head is placed over the tendon onto the
structure to be retained. The bearing plate may rest directly against
the structure or on a specially prepared anchor block attached to
the structure.
When the bonding grout has achieved sufficient strength tendon
is tensioned to the predetermined load by an accurately calibrated
jack. the stressing operation may be performed in any number of increments
and is proof loaded to a tension in excess of the required load.
The force is maintained by the stressing anchorage after release of
the jack.
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Permanent Anchor
The Stewart Drilling Ground Anchor
becomes and integral component of the structure and guarantees
its overall safety. The protection against corrosion is therefore
of the utmost importance.
The
protection against corrosion to ensure longevity is the essential
difference between the permanent and the temporary anchor.
Continuous corrosion protection is provided for the Stewart
Dilling Permanent Anchor by the use of continuous thick walled
polyethylene plastic sheathing over the full length of the anchor.
In addition each strand within the free length is coated in
an anti-corrosion compound embedded inside polythylene sheathing.
The anchorage is protected by casement in high quality concrete
or anti corrosion compound.
the drill hole is subjected to a waterpressure test to check
the imperviousness of the rock. if the drill hole fails the
watertest it is sealed with waterproofing gout, redrilled and
watertested again until the drill hole is satisfactorily waterproofed.
The tendon is inserted into the drill hole and is bonded to
the rock by high strength cement grout and is tensioned to the
required force after the grout has achieved sufficient strength.
Tensioning is by accurately calibrated jack and can be carried
out in any number of stages. The tensioning force is maintained
by the anchorage after the release of the jack.
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