Balfour Beatty drills 13k holes in Devil's Punchbowl project
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London – Balfour Beatty has selected eight Atlas Copco LCD 1500 hydraulic core drills, for drilling around 13,000 holes in the walls and floors of the twin road tunnels for the Highways Agency A3 Hindhead Tunnel project. At 1.8km long, the tunnels running beneath the Devils Punchbowl, will be the UK’s longest non-estuarial tunnels.
The holes in the tunnel shot-crete walls needed to be 40mm diameter, 150 mm deep and drilled every 750 mm at an upward angle using rigs mounted on the concrete shutter units.
The holes in the tunnel floor needed to be 137mm diameter and 220mm deep, drilled vertically every 2 metres using a portable drill rig. Both sets of holes are needed to ensure total stability of the automatic concrete shutter units when forming the concrete tunnel lining sections in-situ.
The LCD 1500 hydraulic core drills chosen for the job were two per shutter, each powered by an Atlas Copco 3 phase electric, 20 litres/minute hydraulic power pack.
“The drilling rate, reliability and robustness of the Atlas Copco [equipment] are far better than the electric core drills being used initially and has saved us a lot of time,” said Dave Carver, tunnel agent for the project. “When you have thousands of holes to drill, time saved on every hole and lack of breakdowns soon adds up.”
