Bau des Tunnels im Zuge der B 260 Umgehung Fachbach - Bad Ems

Work on the B 260 Fachbach to Bad Ems bypass also included a 1,540 metre-long section of tunnel, which was constructed using the open-trench method. The tunnel lies on the lower slopes of the 250 metre-high Malberg hill, which has a gradient of up to 45° in places. In order to calculate slope stability and design the shotcrete and prestressed ground-anchor support system the planning engineers first re-calculated the soil parameters and then used an engineering approach to limit the height of any possible fracture bodies. All slope movements were also monitored by means of an extensive ground survey programme. Some parts of the valley-side tunnel wall were not embanked and the outer lining has been left exposed. The significant horizontal forces acting in this area have to be transferred from the slope through the floor of the tunnel structure, a process which is made more difficult by the presence of a PE membrane. To remedy this, a series of pusher cams was installed beneath floor level.