A3 - dual carriageway link between London and Portsmouth 6.5km new road, 1.77km in bored tunnel...
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Transcript of A3 - dual carriageway link between London and Portsmouth 6.5km new road, 1.77km in bored tunnel...
• A3 - dual carriageway link between London and Portsmouth
• 6.5km new road, 1.77km in bored tunnel• £371 million• Construction started January 2007• Project finish date 2012
Construction Overview• Twin Bore 2 lane Tunnel
• Tunnel Length – 1.2 miles
• Depth – Varies between 20 – 60m
• 7.3m wide 2 lane carriageway
• Estimated Earth Excavation – 300,000 cubic metres
• Longest non-estuarial crossing in England
Solution Adopted• Slope Stability
• Soil Nails
• Geogrid Reinforcement
• Minimising Visual Impact
• Soil Pouches
• Place Soil and Vegetation
• Hydroseed Spray
Solution Adopted continued…..
• Structural Reinforcement for Tunnel Face
• Rock Nails/Bolts
• Short
• Concrete Grout
• Ground Anchors
• Long
• High Tensile Steel
Solution Adopted continued…..
Sprayed Concrete Lining (SCL)
• Roof Supporting Spiles
• Primary sprayed concrete shell
• Waterproofing Membrane
• Reinforcement Steel
• Cast Concrete lining• Shotcrete• 200mm thick
Alternative Methods• New Austrian Tunneling Method (NATM)
• Tunnel Boring Machines (TBM) • New Tunnel PLS (Pre-Lining Support)