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Click on the BBA accreditation
logo to download our BBA Certificate in Acrobat PDF format.
If you do not have Adobe Acrobat Reader you can download it
free here.
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Whitehaven harbour, Cumbria, on the North West
coast of the U.K. was constructed in the 1700’s.
Over recent years a 35 metre section of the internal harbour wall
has slumped, developing tension cracks along the causeway approximately
1.5 metres away from the harbour side.
Weldgrip Gripforce ® fiberglass
rockbolts were chosen to reinforce the ground behind the wall
and prevent further movement. |
Setting the drilling
position from the pontoon >>
The bolts used were 31/15mm (OD/ID) injection tubes 6 metres
in length.
They were installed into 120mm diameter pre-drilled holes angled
down at 15° from the horizontal.
The holes were spaced along the wall at 1 metre centres, each
row being staggered at 0.5 metre spacing. A total of 105 were
used on the project.
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Each rockbolt was fitted with 3 lantern
type centralizers, one at each end and one in the centre. A
material sock was fitted to each tube covering the centralizers
terminating at the thread end. Every threaded end assembly had
a 130mm diameter non-metallic end plate and high load GRN(glass
reinforced nylon) nut with a threaded end capacity of 200kN. |
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<< The tension
crack in the harbour wall causeway
All of the rockbolts were fully grouted using a water/cement
ratio of 0.4%. The grout was pumped through the internal bore
of each tube into the sock.
The sock was used to restrain the grout within the hole from
expanding into any breaks or voids along the reinforcement length.
Use of this system minimizes grout loss within the structure
where large voids are expected and forms a wedge locking action
in the rockbolt hole. |
The drilling operation
>>
The tubes was countersunk into the harbour wall by taking a
stone core 300-400mm deep by 152mm diameter at each rockbolt
position prior to drilling the holes.
To maintain the aesthetics of the wall structure, each stone
core was numbered and replaced in the hole from which it was
taken after the bolts were installed. All the drilling and rockbolt
installation work was carried out from a pontoon moored next
to the wall in the harbour. |
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Gripforce
®
injection
tube installed. |
The
borehole pattern
in the harbour wall |
Grout
being injection into tube. |
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If you would like to print the brochure for more information
on our soil nails and rockbolts please click on the download
button.
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click
here.
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4.2 meg |
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Bar
& 'AT' Rockbolts
Ease of installation