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The Bradway Tunnel maintenance project was part of the upgrading
of the Midland Main Line rail network, and involved replacing
a bulged area of the brickwork lining in the roof and sides.
To achieve this, a temporary support system was required to
maintain the integrity of the brickwork. Weldgrip Fibregrip
® Rockbolts were used to offer a safe support system for
the brick tunnel lining, enabling cutting out and replacement
of the bulged brick section.
A high density of rock bolts was installed in the bulged area
and placed through a polymer geogrid at 0.75m centres in a grid
pattern.
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| The Fibregrip
® Rockbolts used were 22mm diameter x 2m long, with a tensile
and shear strength of 470kN and 129kN respectively.
They were installed in 28mm diameter holes and spun through
polyester resin capsules which had a cure time of 5 minutes.
A standard 80kN nut and a 150mm diameter round high load plastic
end plate was used to tighten the bolt end assembly to the brickwork
and polymer geogrid. The rockbolts were cut back to the tunnel
lining as the bulge
was removed and the brickwork repaired. |
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| The Weldgrip Fibregrip
® Rockbolt system delivered the following advantages to the
maintenance project: |
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Bar
& 'AT' Rockbolts
Safe method of working during installation