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SchlossbergTunnel Dillenburg - B 277

The B 277 links the B 54 and the A 45 near Burbach with the B 49 near Aßlar. Thanks to the building of the 782 m long Schlossberg Tunnel the former two-lane urban highway B 277 to the north of the old part of Dillenburg was relocated thus relieving through traffic to the tune of 18,000 vehicles/ day. The tunnel possesses a RQ 10.5t standard cross-section and was driven by mining means over a length of 622 m. in the north 30.5 m. was produced by cut-and-cover, in the south 130 m. A 151 m long trough structure joins up towards the south. To enhance tunnel safety a 585 m long evacuation tunnel was produced by mining means from the north Portal, which is linked to the road tunnel with three cross passages. Breakdown bays are set up at both sides roughly in the middle of the tunnel, which also provides access to the evacuation tunnel. On account of the legally binding narrow curved radii as prescribed by construction legislation the inner shells of the blocks were produced in steel fibre concrete in some parts. ln addition six blocks were created in self-compacting concrete as a research project. An exhaust air centre built by mining means is set up some 50 m behind the north portal to remove the spent air from the tunnel. It is connected with a roughly 13 m high exhaust stack next to the · operations centre via an exhaust tunnel. Longitudinal ventilation which removes the spent air for standard operation and a smoke removal system in the event of fire are foreseen for the ventilation system. An intermediate ceiling with exhaust flaps that open automatically was installed to remove smoke. Coming from the north the tunnel passes through the Nanzenbach Basin, which consists of Upper Devon clay schist with intervening sandstones as well as diabase with intermediate layers of Alaun schist. This is followed by Dillenburg Saddle diabase and fine gravel, which also continue below the Schlossberg. In the south there is a connecting basin structure with Dillenburg Layers, a succession of clay schist and diabase tuffs. At the south section produced by cut-and-cover there is a 4 to 6 m thick covering layer of loamy Dill gravels, superimposed on the Dillenburg Layers. Over its entire length the tunnel is located beneath the groundwater Ievei, whereby the groundwater lies up to 20 m above the tunnel roof. As a result the tunnel had to be produced as a pressurised water resistant system over its entire length. Towards this end the mined section was provided with a cross-section with closed floor and continuous seal with a plastic waterproofing membrane. In the cut-and-cover section a rectangular crass-section was produced as a watertight concrete structure. At the start of the tunnelling scheme the pre-cuts ta the north and south of the mined tunnel were created. To maintain the flow of traffic the excavation pit for the north pre-cut was spanned by a 27 m long auxiliary bridge during the construction phase. In the south an overlapping bored pile wall was created in zones with adjacent buildings. For the other areas and for the trough section, sheet walls were set up. In the open excavation pit the tunnel cross-section and the t rough section were produced as a watertight concrete structure. In order to avoid interrupting the natural groundwater flow by the tunnel cross -section and the trough section an extensive drainage system was foreseen to ensure that the groundwater circulation was unimpeded. Towards this end a drainage layer was installed between the base of the excavation pit and the bottom plate as well as in the working areas at the side, which enable the groundwater to circulate around the structure after cutting around the piles in the overlapping bored piling wall or removal of the sheet piling.

 

  • Country: Germany
  • Region: Hesse, Lahn-Dill District
  • Tunnel utilization: Traffic
  • Type of utilization: Road Tunnel
  • Client: Federal Republic of Germany, Land of Hesse
  • Consulting Engineer: Bung AG, Gackstatter Beratende Ingenieure GmbH/Dr. P. Kündig
  • Contractor: DYWIDAG
  • Main construction method: Trenchless
  • Type of excavation: Drill-and-blast
  • Lining: Shotcrete
  • No. of tubes: 1
  • Tunnel total length: 782 m
  • Cross-section: 99 to 170 m²
  • Contract Volume: 31 mill. Euro (roughwork), 4.5 mill. Euro (Operating technology)
  • Construction start/end: 2003-2007 (42 months)
  • Opening: April 2007