U-Stadtbahn Essen, Nordstrecke-Baulos 34
Construction lot 34 is a part of the eighth part-section of the Rhine-Ruhr urban railway, construction section Essen. It represents the continuation of the northern section in Altenessen, connecting up with lot 32/33. The construction section begins in the south to the north of the Altenessen Bahnhof underground station and ends in the north to the south of the A 42 motorway bridge. It is roughly 2.5 km long. By and large, the soil encountered comprises silts and coarse silts as well as marl. At some points, the tunnel completely runs through the marl, at others, only its lower part is located in marl. The groundwater level is some 4 m below the surface and must not be lowered. The tunnel tubes are driven by means of a hydro-shield (diameter 8.33 m, weight 600 t and thrusting force of 56,000 kN) segmental lining. A large cross-section was chosen to enable the station platforms and the control rooms to be located in the tunnel tubes. This has the advantage that there is no need for enlargements nor for the stations to be built using compressed air. First of all, the eastern tunnel tube has to be driven from the starting shaft in the south to link up with lot 33. There, the shield jacket is left in the ground to form part of the support. The “guts” are then relocated and set up in the new shield jacket in the starting shaft for driving the western tunnel. In spite of comparable soil formations (geology and hydrology, undercutting buildings, etc.) to lot 32/33, a hydro-shield is being used for lot 34 instead of an EPB shield for technical reasons and due to the separation technology, which has made great advances compared with 1986. For the first time, a so-called centre cutter in the form of a micro tunnelling machine - 1.20 m diameter - is being incorporated, which has its own flushing system and which cuts the soil independent of the main cutting wheel and also transfers the muck to the exit port on its own. The micro machine runs at approx. 12 rpm and greatly contributes to relieving the central section. Tests carried out show that the torque when operating without the centre cutter is some 56 % higher than when it is used. Similar values were registered for the contact pressure of the cutting wheel, which are some 50 % higher when the centre cutter is not used. In contrast to lot 32/33, where a two-shell construction method - comprising extruded and steel fibre reinforced concrete - has been selected for the running section, a monocoque segmental lining is to be used for the large tube for construction lot 34. For an approx. 100 m long test section within construction lot 34, the tunnel lining will comprise steel fibre reinforced concrete segments.
- Country: Germany
- Region: Nordrhein-Westfalen
- Tunnel utilization: Traffic
- Type of utilization: Underground, urban and rapid transit
- Client: Stadt Essen, U-Bahnbauamt
- Main construction method: Trenchless
- Type of excavation: Shield machine (SM)
- Lining: Reinforced concrete segments
- No. of tubes: 2
- Tunnel total length: 2 x 2404 m
- Outer diameter: 8.33 m ≙ 54.47 m²
- Inner diameter: 7.27 m ≙ 41.50 m²
- Contract Volume: (Raw Construction) 301 mill. DM
- Construction start/end: 25. 10. 1990 till 30. 4. 1997