Tunnelling Under the Thames

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Alan Spray Ted Allen Docklands Light Railway (DLR) Woolwich Extension

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Alan Spray Ted Allen. Tunnelling Under the Thames. Docklands Light Railway (DLR) Woolwich Extension. Geological Context. Initially Alluvium, gravels and Bullhead beds Water-bearing Upper Chalk Non-Clastic Carbonate Cretaceous period Medium – wide joints - PowerPoint PPT Presentation

Transcript of Tunnelling Under the Thames

Page 1: Tunnelling Under the Thames

Alan SprayTed Allen

Docklands Light Railway (DLR) Woolwich Extension

Page 2: Tunnelling Under the Thames

• Initially Alluvium, gravels and Bullhead beds

• Water-bearing Upper Chalk• Non-Clastic Carbonate • Cretaceous period• Medium – wide joints• Large flints – non carbonate• Relative strengths

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Flint damageWater-bearing chalk

Maintenance – dry refuges

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Drilled until cutter broke

Intensive pumping - luck

Repairs to cutter Dig heading Replacements/reinforcements Welding

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Stronger cutters

Better investigation More remedial works

Build a bridge

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