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Tunnel Krämerskuppe

This is a two-track tunnel some 840 m in length which was driven by mining means. The excavated cross-section of the tunnel tube amounts to almost 140 m². Following the drive, the base invert was lined with 40 cm thick, watertight concrete, whereas the 40 cm thick inner shell of the vault fitted with a seal comprises B 25 standard concrete. The special feature about the Krämerkuppe Tunnel was that when the mined section was undertaken starting at the southern portal, the six-lane federal motorway (BAB 7 Kassel- Fulda) had to be undercut at the Reckeräder Berg over a distance of 170 m The drive below the autobahn coincided with the peak holiday period so that any hampering of the motorway traffic was undesired (e.g. a diversion) and had to be avoided at all costs. In spite of the slight overburden, which amounted to 6 m at the starting point, 9 m at the approach to the motorway and increasing to 15 m at the end of the second carriageway, a maximum settlement value of 50 mm for the roadways was determined in advance. In this particular case, the installation of pipe screens was given the green light in order to improve the surrounding ground. Through their installation, it was intended to improve the rock through advance grouting as well as facilitate the driving of the crown section through the longitudinal bearing capacity of the individual, almost horizontal bored piles. For excavating the crown (approx. 60 m²) an electrically operated road header - type DEMAG H 41 was chosen. The alternating beds of clay and sandstones could easily be cut. On account of the depth of attack of a = 75 cm, it could always be ensured that the layers of rock did not break through to the screen of pipes. The bench was driven in 10-12 m sections. The complete base invert was then installed immediately in 3-4 m lengths regressively. After the watertight concrete base had been installed, a foil seal was placed in the vault and then the vault was concreted.

 

  • Country: Germany
  • Region: Hessen
  • Tunnel utilization: Traffic
  • Type of utilization: Main-line rail
  • Client: Deutsche Bahn AG
  • Main construction method: Trenchless
  • Type of excavation: Roadheader
  • Lining: In-situ concrete formwork
  • No. of tubes: 1
  • Tunnel total length: 840 m
  • Cross-section: 140 m²
  • Contract Volume: 23 mill. DM
  • Construction start/end: 1984-1986 (2 years)
  • Opening: 1986