 |
| Project
Title |
Brokenberry
Quarry Rock Netting |
| Client |
South West Water |
| Consultant |
Drilltec (Northern) Ltd |
| Main Contractor |
Miller Civil Engineering
Ltd |
| Featured
Products |
Weldgrip Fibregrip
® Rockbolts, Drilling Machines & Drill Steels |
|
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The Brokenberry Quarry sewage treatment
works scheme is a South West Water project to upgrade and improve the
water quality in the highly populated summer holiday area of Torbay.
The quarry is situated to the south of the bay between
Brixham and Painton. The project was managed as a partnership between
Miller, Hyder and South West Water. Rock Netting the quarry face was part
of the first phase of redeveloping the site. The floor was excavated to
level the ground, remove the infill left after quarry operations finished,
and expose the quarry face ready for reinforcing.
The height of the walls varied between 5 to 15 metres.
The whole quarry face was netted from top to bottom using PVC coated mesh
which was held in place by Weldgrip Fibregrip
® Rockbolts. The bolts were installed into small bore diameter holes,
which were drilled using Weldgrip Gopher drilling machines. The pneumatic
rotary drilling machines were secured in purpose built frames mounted
in telescopic hoists.
Weldgrip hexagon drill steels and 27mm twin winged bits
completed the drilling system to give nominally 28-29mm hole diameters
in the medium to hard sandstone. Fibregrip
® 22m diameter 1.8 metre long polyester rockbolts were used to secure
the netting.
The bolts have tensile and shear strengths of 470kN
and 129kN respectively. A breakout nut capable of withstanding 45Nm of
torque was used to install the bolts.
This enabled each bolt to be spun to the back of the
hole through resin capsules, using the Gopher drilling machine and a spinning
adapter. Polyester slow set resin capsules were used to bond the rockbolts
into the strata. These have a cure time of approximately 5 minutes after
mixing.
The rockbolt end assemblies consisted of a 150mm diameter high load plastic
end plate and a GRN (Glass Reinforced Nylon) nut capable of withstanding
80kN of end load
The end assemblies were tightened to the wire
mesh after the resin had cured. This allowed the torque setting to be
overcome and the nut to be run up the thread.
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- 620k |
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- 360k |
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Weldgrip are also proud to have attained
BBA accreditation and ISO 9001 standards in recognition of our continuing
excellence in Geotechnical products and services. |
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