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Tunnel Allach, Munich

The construction of the main contract "Tunnel Allach" began on 1.10.1990. As preliminary measure in spring 1990 in the rail section of the Federal Railway (DB) main track the walls and bottom anchoring for the future building pit were made. Afterwards the three rail tracks could be laid on 60 m long auxiliary bridges from the bridge equipment yard of the Federal Railway. They were spanned over the later opened building pit without columns. Due to these preliminary measures the further building pit and tunnel works below the rail tracks could be executed independent of the railway service. The tunnel was made in 9 open building pits which are between 110 and 220 m long. The different construction phases of a building pit are as follows:

  • The building pit was constructed by sheet pi les down to 16 m depth.
  • Excavation down to the groundwater and execution of the grout anchors.
  • Excavation below the water down to a depth of 13 m.
  • Sealing of the building pit at the bottom with an approx. 1.20 m thick below water concrete layer; due to the enormous uplift the concrete layer had to be anchored down in the soil. Therefore grouted piles (about 10.50 m long) had previously to be inserted by vibration equipment of 4/4 m.
  • Pumping of the groundwater from the building pit and execution of the building.

The water pumped out of the singular building pits was locally infiltrated again in the ground. For this purpose infiltration wells were made when the infiltration basin for the surface water made for future tunnel operation was not sufficient. Within the single building pits the tunnel with a total width of 34.60 m was made in 10 m long sections of concrete B 25/B 35 (WU). The construction joints are to be found in the respective externa1 walls above the average groundwater level, i.e. bottom and external walls had to be concreted within one step. The centre wall and ceiling were constructed apart. Between the single sections there are flexible joint tapes with vulcanized plate strips and grouting facilities. All joints are additionally secured by outlying joint tapes. Thus the entire tunnel construction is watertight and due to its own weight founded with safety against uplift. Because of reasons of protection against fire the concrete cover of the reinforcement for tunnel ceiling and walls were raised to 65 mm. This cover contains an object reinforcement of hot-dip galvanized reinforced steel mesh. Because of the lightning technique in the tunnel concrete roadways are constructed, because of the noise in the ramp area drain-asphalt roadways are used.

Construction tunnel Allach

Total length of the construction: L 400m – tunnel length: 1,030 m - ramps: 200 and 170 m width of road: 2 x 14.00 m (3-lanes 3.50 m each, 2.50 m emergency lane) clear width between the external tunnel walls: 2 x 16.10 m clear height: 4.80 m construction width: 34.60 m two-cell reinforced concrete frame, safe against uplift by own weight (white sump, ceiling and road sealing)

Construction of tunnel pits wall sheeting: with sheet piles and grout anchors, 1 layer (regular construction). Overlapping bore pile walls, cofferdam (special construction). Ramp sectors along 100 m length heavy weight base plate.

 

  • Country: Germany
  • Region: Bavaria
  • Tunnel utilization: Traffic
  • Type of utilization: Road tunne
  • Client: Federal Republic of Germany, Ministry of Traffic
  • Main construction method: Open
  • Type of excavation: Cut-and-cover
  • Lining: Concrete formwork
  • No. of tubes: 1
  • Tunnel total length: 1400 m
  • Contract Volume: 162 Mio. DM
  • Construction start/end: 1990 till 1995
  • Opening: 1995