Cable conduit slabs in the “Grouft” tunnel

Evaluation of various designs

As part of the design of the Grouft tunnel project in Luxembourg, various options for slabs covering the cable conduits on both sides of the carriageway have been investigated in terms of their structural strength. In this exercise, various types of slabs consisting of reinforced concrete, steel-fiber reinforced concrete and a combination of these two materials were tested. In some cases, their edges were enclosed by a hot-dip galvanized angle plate in order to protect the edges and the contact zones. Apart from their structural strength, the cable conduit slabs were also evaluated and compared with respect to their ductility. The tests demonstrated that only the slabs with uniformly distributed rebars were able to withstand the required loads while at the same time showing only narrow crack widths.

North of the City of Luxembourg, a 3-km tunnel is currently under construction (Fig. 1). This tunnel forms part of the new “Route du Nord” section and consists of two main tubes, one of which accommodates three lanes while the other has been designed for two lanes, running at a gradient of almost 5%. Tunneling works are carried out by a consortium of contractors including Wayss & Freytag, Max Bögl, Galère, Tralux und Félix Giorgetti using both a conventional method and blasting. The tunnel connects the “Heeschdrëfferbierg” plateau in the south to the Alzette valley near Lorentzweiler in the...

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