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Zürich, Switzerland

Rudolf A.,ILF Consulting Engineers AG | Kienzler T.,Engineering services
Underground - The Way to the Future: Proceedings of the World Tunnel Congress, WTC 2013 | Year: 2013

The meteorological pressure difference between tunnel portals is an important parameter for ventilation designs. If tunnel portals are not too far away, it is possible to measure the pressure difference directly. However, with augmenting tunnel length, the use of pressure tubes and a differential pressure measurement becomes increasingly difficult, because the influence of the local variations of the air inside the tunnel on the measured overall pressure difference is difficult to compensate. In these cases, it is necessary to measure the absolute pressures at the portals with a precision sufficient to provide useful pressure differences for the ventilation design. The present paper describes a measurement installation which has been used in the longest tunnel with directional traffic in Switzerland, the 9.2 km long Seelisbergtunnel. In this project, the required precision of the measured pressure difference was 10 Pa as this was the preliminary estimated value. The present paper informs about the technique used, the problems encountered and the results. © 2013 Taylor & Francis Group. Source

Marcher T.,ILF Consulting Engineers ZT GmbH | John M.,JTC John Tunnel Consult | Hohberg J.-M.,IUB Engineering Ltd. | Fellner D.,Axpo Power AG | And 2 more authors.
Underground - The Way to the Future: Proceedings of the World Tunnel Congress, WTC 2013 | Year: 2013

A 1,000 MW pumped-storage plant is under construction at altitudes between 1,600 and 2,400m in the Glarner Alps of Switzerland, around 90 km south-east of Zurich. The machine and the transformer caverns are situated in Quintner Limestone with an overburden of 400 to 500 m. The 150 m long machine cavern has a height of 53 m and a width of approximately 30 m. The distance between both caverns was increased to 59 m to avoid overlapping plastic zones following the evaluation of geological conditions of the pilot tunnel. During construction it was found that geological conditions are more complex than expected, resulting in displacements varying to a large degree. That was why the design was reviewed by comparing the prognosis with the actual behaviour during excavation of the heading. The rock bolting system with regard to pattern and length was adjusted based on the results of numerical back analyses including sensitivity studies of the rock mass parameters. Additional 3D computations were performed to take account of the numerous intersecting galleries. During excavation of benches, additional rock bolting was provided in specific areas, where deformations continued over some time. © 2013 Taylor & Francis Group. Source

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