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The Porthkerry No.1 and No.2 Tunnels were the first in a series
of twelve to be refurbished on the Great Western Region rail
network.
Maintenance work involved the reinforcement of the tunnel lining
by casting concrete toe blocks 1.5m long at 4m centres either
side of the tunnel. The toe blocks were anchored to the brickwork
by Weldgrip Fibregrip ® Rockbolts.
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| Between opposite toe blocks on either side of the tunnel a 250mm
wide waterproofing membrane was positioned round the brickwork
before sgortcreteing a 150mm thick permanent arch strip to complete
each section. |
Two Weldgrip Fibregrip
® Rockbolts were used to secure each toe block at 750mm centres.
The rockbolts were 22mm diameter, 3m long and fitted with a standard
80kN nut and high load 150mm square plastic end plate.
They were installed into 32mm diameter holes which had been drilled
by pneumatic rotary drilling machines. |
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| Full encapsulation was achieved by spinning the rockbolts through
polyester resin. |
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Other GWR Tunnels to have used this system include:
- Box Tunnel
- Caerphilly Tunnel
- Whiteball Tunnel
- Crocket Tunnel
- Sugerlaof Tunnel
- Cogan Tunnel
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The 205m long Tytherington Tunnel was also refurbished as
part of this program.
Weldgrip Fibregrip ® Rockbolts
were used as the sole means of reinforcement into an area of
the limestone roof. These were 25mm diameter x 3m long, installed
into 32mm diameter holes and spun through polyester resin capsules.
The nut was tightened to a 150mm square high load plastic end
plate assembly.
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on our soil nails and rockbolts please click on the download
button.
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click
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Bar
& 'AT' Rockbolts
