Skip navigation

Dölzschen and Coschütz Tunnels

The Dölzschen and Coschütz Tunnels were produced on the south-western periphery of Dresden as part of the A 17 federal motorway from Dresden to Prague. Both tunnels consist of 2 parallel running tubes each with an excavated cross-section of some 150 m², which are linked by cross-passages at 300 m intervals. The 2 tunnels were produced by trenchless means largely by drill+blast by the NATM. The ground that was penetrated mainly consisted of syenite of weathering categories I to IV, a magmatic irruptive rock, which was to be found partly fragmented with completely separated, smooth fissures to some extent comprising harnisch and in some parts as widely spaced and incompletely separated high strength rock. The tunnels' maximum overburden amounts to some 40 m. The inner shell's standard cross-section has a width of roughly 15.40 m and a height of around 11.00 m and is provided with a pressure water retentive membrane seal. The maximum water pressure height for the Coschütz Tunnel is attained some 38 m above the tunnel floor. In this sector, a deeper and thicker base invert was created for static reasons. A special challenge in the case of the Coschütz Tunnel had to be met when undercutting a brewery with hop silos that were prone to Settlements and a brew house. Various measures were undertaken to minimise the Settlements during excavation such as adjusting the blasting parameters, an umbrella shield in the crown area, reinforced face support, grouting and crown base piling. The 2 tunnels are linked to one another by means of the Weißeritz Valley Bridge. The south portal of the Dölzschen Tunnel forms a unit with the bridge abutment. Here the tunnel meets a perpendicular rock wall some 70 m high, which was secured using tensioning bolts on account of the rock mechanical situation. The edge of the excavation was additionally supported with rock bolts on a permanent basis in order to prevent any asymmetrical load on the portal block and provided with a yielding intermediate layer between the outer and inner shell. It was also essential to ensure that the Begerburg perched on a ledge above the rock wall was not jeopardised by blasting operations. As a consequence, the ledge on which the historic building is situated was secured in advance using rock bolts.

 

  • Country: Germany
  • Region: Saxony
  • Tunnel utilization: Traffic
  • Type of utilization: Road tunnel
  • Client: Federal Republic of Germany, Land of Saxony
  • Consulting Engineer: Schüßler Plan, Prof. Dr.-lng. Dieter Kirschke
  • Test engineer: Prof. B. MaidI
  • Construction monitoring: Bung Beratende Ingenieure
  • Contractor: Walter Bau-AG
  • Main construction method: Trenchless
  • Type of excavation: Drill-and-blast
  • Lining: Shotcrete
  • No. of tubes: 2
  • Tunnel total length: Dölzschen Tunnel: eastern tube 1,082 m, western tube 1,052 m; CoschützTunnel: eastern tube 2,306 m western tube 2,338 m
  • Cross-section: 150 m²
  • Contract Volume: approx. € 126 million
  • Construction start/end: May 2000 to December 2004
  • Opening: 2004