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Mangfall, Mühlthal, Hachingen galleries

The Water Supply Department ot the "Stadtwerke München", in a long term project, is replacing its over 100 year old free-flow water pipes from the Mangfall Valley by a new gradient pressure pipe in the mining method. The first 10 km, the sections known as the Mangfall Gallery and the Mühlthal Gallery, of the approximately 30 km long project have been completed and have become operational by a temporary connection to the existing system. The last approximately 2.4 km long section, the Hachinger Gallery, will be turned over to the client in 2000. The galleries are lying deep in the tertiary strata. In the Mangfall/Mühlthal Galleries, these are tertiary sands, clays, silt and marl as well as, in part, very hard tertiary conglomerates. In the Hachinger Gallery, mainly tertiary marl and sands have been encountered. The tunnels have been driven with a Lovat TBM. This TBM is capable of driving as an open shield with a conveyor system, as a shield operating with an earth pressure flap and a conveyor system, and also in the classical earth-pressure-balance operation with a screw conveyor. This TBM was suitable for all geological and hydrological formations to be expected. The shield was 3.40 m in diameter. The gallery is lined with reinforced concrete segments, 18 cm thick and 1 m long, each ring consisting of 6 segments. In the Hachinger Gallery, the segments were reinforced with steel fibres. The segments, which are all of nearly the same form, were made in a special production process. They are bolted in the ring direction and connected by dowels in the longitudinal direction. The annular space was filled with grout. Because of the uncomplicated operation of the TBM and the simple segments, very good driving results could be obtained. The contractual average output of 25 m/working day was achieved. The clear internal diameter was 2.90 m. ln the completed galleries, steel pipes DN 1800 and DN 2200 were installed and welded together. The gap between the steel pipes and the segments was filled with a hydraulic binding filler. The steel pipes were internally lined with concrete mortar. In a full scale test, pipe installation, back stowing with insulation and concrete mortar lining were tested. The shafts, up to 50 m in depth, were constructed in a combination of drilled piles and shotcrete method.

 

  • Country: Germany
  • Region: Bayern
  • Tunnel utilization: Utilities
  • Type of utilization: Water
  • Client: Stadtwerke München
  • Contractor: Bilfinger + Berger Bau AG
  • Main construction method: Trenchless
  • Type of excavation: Shield machine (SM)
  • Lining: Reinforced concrete segmants
  • No. of tubes: 1
  • Tunnel total length: 591 m, 4833 m, 3994 m
  • Diameter: outer diameter 3.40 m, inner diameter 2.90 m