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lslisberg Tunnel- A4

The lslisberg Tunnel consists of two parallel road tunnels on the A4 national highway near Zurich in Switzerland, which is the longest underground section of the Zurich West Bypass. The tunnel comprises the west and east tubes each with 11.8 m external diameter and an excavated cross-section of 100 m². The two tunnel bores run 25 m apart with varying overburden ranging from 20 to 111 m. The machine for the lslisberg Tunnel's west tube began excavation work in April 2004. Characteristic rock formations along the route are sweet water molasse, chalky silt stones with intermittent clay and sand deposits as well as fine sandstones, which could be tackled without any problem using a simple shield TBM. The tunnel was provided with a sealed lining consisting of 5 + 1 reinforced concrete segments to secure the excavation. The 2 m long ring segments were installed parallel to the drive protected by the TBM's tail skin. The lining has an internal diameter of 11 m, the segmental ring external diameter amounts to 11.60 m. Driving the west tube with a length of 4,680 m ran according to schedule with average weekly rates of advance amounting to 100 m. After 54 weeks of single shift operation the TBM reached the previously excavated crown at the south portal on April 21st, 2005. Subsequently the cutterhead was dismantled in the southern pre-cut and the trailers pulled back through the tunnel. Then the TBM was assembled to drive the 4,666 m long east tube. Here too the site crew attained weekly peak rates of up to 112 m. On July 12th, 2006 the breakthrough of the east tube was celebrated following less than a year's excavation work. The tunnelling machine comprised the cutterhead, the shield and the 160m long back-up structure. The tunnelling installation possessed a total weight of 2,000 t. The cutterhead was fitted with 69 roller bits (17” diameter). The rock was loosened by rotating the cutterhead and transported to the belt conveyor by means of buckets. The excavated material was carried via conveyor over the back-up installation, transferred to the tunnel belt conveyor and was then passed through the tunnel to reach the rail loading point. The thrusting force of max. 51,700 kN required for the excavation was produced by driving jacks, which were supported on the segmental ring last installed. Following a 2 m advance the driving jacks were retracted and the segments placed protected by the shield. Beneath the shield the annular space in the floor area was filled with mortar and elsewhere with pearl gravel. The prefabricated utility duct elements were installed below the trailers and filled up at the sides with stabilising excavated material. The east tube's inner furnishing work commenced at the same time as the east tube excavation. This included the seal, the inner vault, the intermediate ceiling as well as the road building operations.

 

 

  • Country: Switzerland
  • Region: Zurich Bypass
  • Tunnel utilization: Traffic
  • Type of utilization: Road Tunnel
  • Client: Baudirektion Kanton Zürich, Foundation Engineering Office, Construction and Value Retention
  • Consulting Engineer: Ingenieurgemeinschaft N4. 1 .6- Amt: Pöyry Infra AG, Dr. Vollenweider AG, Ernst Winkler +Partner AG
  • Contractor: JV lsllsbergtunnel (IBT), Marti Tunnelbau AG/Ed. Züblln AG/Marti AG Bauunternehmung
  • Main construction method: Trenchless
  • Type of excavation: Shield machine
  • Lining: Reinforced concrete segments
  • No. of tubes: 2
  • Tunnel total length: 9,346 m
  • Contract Volume: 500 mill. CHF (roughly 344.76 mill. Euro)
  • Construction start/end: 2003 till 2007
  • Opening: April 21st, 2005 (breakthrough, western tube), July 12th, 2006 (breakthrough, eastern tube)