CREG TBMs accepted for Dubai stormwater tunnel

The 11.05m-diameter EPB machines underwent factory acceptance in July. They will have a main drive rated for 4,200kW and at 100m-long, will weigh some 1,500t.

The project is being constructed by a joint venture of Porr and Six Construct. It is scheduled to be finished ahead of Expo 2020 Dubai, in October of that year. A total of more than 600 international experts are currently involved in the project. The contract value is around EUR 300M (USD 350M).

The DTSWS is a 10.4km-long tunnel that will transport groundwater and stormwater runoff from the 135km2 Dubai World Central area – the new ‘airport city’ – and adjacent communities, in total spanning around 245km2. The tunnel will have a 10m inner diameter and will run at a depth of 30 to 40m. Additionally, four 20m-diameter shafts will be sunk to a depth of 45m, four connecting adits between the drop shafts and the tunnel, and 2x385m DN 3000 pipe-jacked tunnels.

The tunnel will be driven through the Barzaman and Fars formations. The Barzaman formation consists of conglomerate, calcisiltite and calcilutite and the Fars formation consists mostly of mudstone and calcilutite. 
“Soil investigations were performed as part of the preliminary design by Dubai Municipality along the alignment of the tunnel as well as additional soil investigations after the award of contract by the JV,” says Chris Ashton, tunnel manager at Porr.

The tunnel will be lined with 350mm-thick steel fibre reinforced concrete segments in an 8+0 arrangement. There will be universal rings with double tapered segments.

Porr CEO Karl-Heinz Strauss said: “Two starting shafts have already been excavated and NATM works have began to build the underground starter caverns for the later tunnel boring machine assembly. The Factory Acceptance tests of TBMs have been successfully completed and the machines are expected mid-October in UAE. Until the time of TBM start-up, the JV will work on segment production.”