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Metro Munich, Line U2 North, construction lot 8 - Station Feldmaching and running tunnels

Construction Lot 8 comprises the terminal station of Line 2 North, which links the Underground and the S-Bahn networks, a siding and the lines leading towards the city. The route tunnels were driven by shotcreting using compressed air in order to avoid major groundwater lowering ln order to restrict the amount of pressure in the working chamber, the groundwater in the tertiary sands of the 2nd groundwater level was lowered. In order to avoid the involvement of private property, at first a space-saving 2-track cross-section was executed over a length of 400 m. Only then was it possible to drive 2 individual tunnels (230 m in length). Cement-bentonite injections were required from the surface in order to reduce the air permeability of the gravels. The enlargement sections with an overall excavated area of a maximum of 115 m² were split into 3 part-headings. The 2-track route section with an overall excavated area of approx. 80 m² was driven in 2 part-sections. The locks and the compressor plant were installed in the eastern blocks 1 and 2 - buildings which had previously been constructed. The lock facility comprised a 3-chamber man lock, suitable in each case for accommodating 10 persons and equipped with respiratory equipment, a 20 m long material lock and a lock for large equipment with 250 m³ volume. 11 screw compressors, capable of producing 660 m³/ min, were installed to generate compressed air. 56 m³/min was available for working air. Altogether around 140 million m³ was required for the entire air consumption As far as the air consumption is concerned, it must be observed that the reduction in July 1992 can be attributed to a blow and the cessation of work. The clear reduction as from March 1993 is the result of successful sealing measures with the shotcrete shell partly being coated with plastic mortar and partly with a 2 to 3 cm thick shotcrete layer in the crown area after the first cracks appeared there.

 

  • Country: Germany
  • Region: Bayern
  • Tunnel utilization: Traffic
  • Type of utilization: Underground, urban and rapid transit
  • Client: Landeshauptstadt München, U-Bahn-Referat
  • Consulting Engineer: U-Bahn-Referat
  • Contractor: Beton- und Monierbau GmbH, Max Bögl GmbH & Co. KG
  • Main construction method: Trenchless
  • Type of excavation: Drill-and-blast
  • Lining: Shotcrete
  • No. of tubes: 2
  • Tunnel total length: 1110 m
  • Diameter: 40 to 115 m²
  • Contract Volume: 107 mill. DM
  • Opening: 1995