Chienberg Tunnel, Sissach

The 2,300-metre Chienberg Tunnel forms the core of the Sissach bypass. It was cut into the highly geologically challenging mountainside of the Tabel Jura mountain range, which posed a mining highlight on account of its extremely swellable Gipskeuper formation.

The road tunnel was constructed in the conventional manner in cross-sections of 11 to 143m2 and subject to rigorous technical and regulatory restrictions. It involved working from several starting points in the middle of a residential area, with little space in the area between the cavity and building structure in some stretches of the tunnel.

Unconsolidated rock headings with sub-sections were used to excavate the first pilot galleries with pipe umbrella support systems, drill and blast with dry drilling and a TBM heading with an open gripper machine. The demanding logistics (multifunctional steel bridge, crushing, conveyor and railway loading facilities with an interim storage facility, cement produced on site using ice instead of mixing water) that the complex project gave rise to and the constraints imposed by the subsoil and available space on site fully proved their worth.

Specialities:

  • First gallery with TBM: Ø 3.50 m
  • Conventional pipe umbrella support system: d = 168 mm, 10 km
  • AT pipe umbrella support system: d = 114 mm, 4 km
  • Micro-piles for calotte abutments: 8.2 km
  • Shaft sinking: Expanded by raise boring machine and explosives, sealed and smoothed
  • Ring closure of the interior vault: 300 m after the calotte breast
  • Cement quality: B60/50 at 80 cm vault strength
  • Removal by rail and deposit of excavated material: 500,000 t

Map

Specific figures

Contract value

CHF 153 million

Tunnel length

2,300 m (of which 1,440 mined)

Normal cross-section

113 m2