Design and construction of the Thames Water Lee Tunnel Shafts, London: Part 2. Construction of the shaft base plugs, slipformed inner lining and annulus infill

摘要

Thames Water has initiated the Thames Tideway Tunnels programme as a key component of the upgrade of London's combined sewer and storm water system of wastewater disposal. The first section to be constructed is the 6.9km long, 7.2m internal diameter, Lee Tunnel between Beckton Sewage Treatment Works and Abbey Mills Pumping Station complex. The Lee Tunnel will intercept the storm flows currently discharging to the River Lee via the outfall at Abbey Mills. The project requires four shafts, the largest and deepest ever to be built in London. Three of the shafts are sited at Beckton and the fourth at Abbey Mills. Diaphragm wall depths range from 84m to 98m and finished internal diameters from 20m to 38m. Each shaft has a primary reinforced concrete lining formed of diaphragm walls and a secondary fibre reinforced concrete lining formed by slipformed shutters. The paper describes the unique technical challenges posed by the four shafts and the solutions adopted. The installation of the diaphragm walls which form the primary lining for the four deep shafts is described in Part 1 of the paper. The design and construction of the secondary lining of the first shaft to be completed (the Beckton Overflow Shaft) is described in Part 2.