The drive for the new, parallel tube for the Schluechtern rail tunnel in Germany has been completed with the breakthrough of Wirth’s dual-mode TBM.
The existing Schluechtern tube, on the Frankfurt-Fulda section of the network, was built in 1914.
The 10.24m diameter TBM was launched in April 2007 and holed through in March, having bored the new 9m i.d. tunnel, built of 2m long rings, at a distance of 50m-70m from the existing tube.
The shield excavated the new, 3995m, long tunnel through alternating strata of sandstone and clay.
Equipped with 71 discs plus 268 rippers and teeth, it has a cutterhead torque of 6800kNm in open mode and 20,300kNm in closed mode. Thrust in the different modes are 17,750kN and 24,800kN, respectively.
Following installation of track, electrical and signalling equipment, rail services will switch from the existing 3576m long, twin-track tunnel over to the new tube. During that phase the new tube will also carry twin tracks but eventually both tunnels will be converted to single track operation.
The refurbishment project, which constitute Phase 2 of the project, will also see the old tunnel lengthened by 60m to be 3636m long. In addition, the base of the tunnel is to be excavated up to 2m for construction of a stabilising slab and the new, reinforced concrete inner lining.
The new rail tunnel and refurbishment of the older tube are being undertaken in a US$258M project by the network infrastructure company, DB Netz.
The client is beginning a similar new build and refurbishment project at the Kaiser Wilhelm tunnel (see p13).
Breakthrough
