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Wehrhahn Line Düsseldorf, Section 2, Underpinning the Kaufhof store at Königsallee

The regional capital of Düsseldorf is producing the so-called core section, the Wehrhahn Line, in the form of an underground urban railway route in order to improve public commuter transportation. The new 3.5 km long urban railway route with 6 underground stations and 2 stations on the surface runs underground from the Bilk S-Bahnhof to the Wehrhahn S-Bahnhof and by and large follows the Elisabeth/ Kasernenstraße and Schadowstraße/ Am Wehrhahn roads. Contract section 2 involves continuing the roughwork for the Heinrich-Helne-Allee Metro Station. A considerable part of this scheme concerns underpinning the Kaufhof store building on the Königsallee, which is landmarked. On the basis of a special proposal the station is being produced by mining means in conjunction with subsoil freezing. The frozen zone fulfils both a static and a sealing function during the construction period. Horizontal freezing pipes are bored around the subsequent excavated cross-section to establish this frozen zone. After setting up the freezing pipes the cylinder-shaped, roughly 2.50 m thick ice zone is produced during a freezing phase, first of all for the central part then for the side sections. The freezing process is undertaken by aggregates with a total freezing rate of approx. 1,200 kW. A 30 % watery salt solution with a temperature of – 35° C is pumped through the freezing pipes as the freezing agent. The drive by mining means subsequently takes place in a number of construction phases for a 3-part tunnel cross-section. Compensation grouting is undertaken to protect the Kaufhof from harmful deformations. A precision height control system (level gauges) with 152 individual sensors was installed in the premises in the basement of the Kaufhof for monitoring purposes during the driving operations. Prisms on the Kaufhof's outer façades round off the technical surveillance of the construction activities. The ground freezing procedure will first be deactivated once the station's inner shell has been installed and the structure attached to the tunnel tube ensuring it is watertight.

 

  • Country: Germany
  • Region: Düsseldorf, North Rhine Westphalia
  • Tunnel utilization: Traffic
  • Type of utilization: Underground, urban and rapid transit
  • Client: City of Düsseldorf
  • Consulting Engineer: Max Bögl (Design)/Ing. Büro Vössing GmbH (Execution)
  • Contractor: Max Bögl Bauunternehmung GmbH & Co. KG/Wayss & Freytag Ingenieurbau AG, Central Division, based in Düsseldorf
  • Main construction method: Trenchless
  • Type of excavation: Drill-and-blast
  • Lining: Shotcrete
  • No. of tubes: 1
  • Tunnel total length: 123 m (Heinrich-Heine-AIIee Station)
  • Contract Volume: 71 mill. Euro net. (roughwork)
  • Construction start/end: 2008 till 2013