Builder: German Railsways, DB Netz AG, Berlin
Contractor: ED. Züblin AG, Direktion IU Tunnelbau, Stuttgart
MEVA Systems: Mammut wall formwork, standard and with trapezoidal strips, Used Mammut 350 wall formwork that was regenerated to deliver a top architectural concrete surface, Climbing scaffolds KLK 230, Folding platforms KAB 190, MEP shoring towers, Timber fillers - special forms
Engineering: MEVA Formwork Systems, Munich office
The Munich-Nuremberg-Berlin line is a major axis within the German railway network and being upgraded for high-speed traffic. North of Nuremberg where the line passes through hillside area, a second tunnel tube is being added to a tunnel built in 1844 and known under the name Burgberg tunnel. MEVA formwork is used to pour the retaining walls, concrete beams and tunnel portals at both tunnel entries, plus bridge abutments and piers close to the southern tunnel entry. The building site is narrow, the workflow complex and the schedule tight. High demands with regard to the concrete finish, inclined areas and concrete surfaces with a board pattern added to the challenges. The MEVA engineers found ways and solutions to master them all.
Abutments with a board pattern and rounded bridge piers
The base slabs for the abutments and the piers for the railway bridge over the Schwabach river at the southern tunnel entry were poured with the heavy-duty Mammut wall formwork. The system‘s 97 kN/m² allowed the 4.29 m high piers to be poured in only one cycle. The board pattern for the abutments was easily achieved with boards attached to the panel facing. Wooden fillers for the inclined lower sides of the wing walls of an abutment and the special forms for the rounded piers were supplied by MEVA’s partner Kiefer, a company specializing in the production of special forms.
Top architectural concrete surface to be achieved with rental formwork
A top architectural concrete surface was demanded for a 27.5 m long retaining wall, which is 6.10 m to 10 m high. Yet pouring had to be done not with new but with used rental formwork. Not a problem with MEVA panels and their alkus all-plastic facing. Scratches, nail holes and other damages on the facing can be repaired – even on site between the pour cycles – and the facing is like new, delivering a top concrete surface from the first to the last pour. Used Mammut 350 panels were regenerated for this job at a MEVA plant and then ganged on site to pour the wall in cycles up to 10 m wide and 2.90 m high.
„I am thrilled by the top architectural concrete surface we have achieved with the regenerated rental formwork,” says foreman Mario Thiele with a smile. He is also impressed by the stability of the Mammut 350 panels that handled the heavy loads with only few ties.
A special solution to master an unconventional pouring order
A special solution had to be found for another retaining wall. Here, the 2.38 m high concrete beam that extends horizontally over the bore piles and the concrete shell covering the front of the bore piles had to be poured before – and not after – the concrete shell below it. Hence, the conventional pouring method – climbing cycle by cycle from the bottom to the top – was not feasible. Another challenge were the enormous loads that had to be transferred from the heavy concrete beam that overlaps the bore piles and concrete shell on both sides. A heavy-duty support structure that would carry the Mammut wall formwork, serve as a working platform, transfer the loads and could be attached to the bore piles was a must and KLK 230 climbing scaffolds were the ideal solution for these requirements. In a second step, the 85 m long concrete shell was poured with an architectural concrete surface using regenerated Mammut 350 panels. The job was accomplished with 10 length cycles and 4 height cycles.
Last but not least: New tunnel portals with a „historical look“
The portals of the old and the new tunnel tubes are located side by side on either tunnel end. Built in 1844, the Burgbergtunnel is Bavaria‘s oldest railway tunnel and a listed monument whose portals must not be changed. In order to preserve the historical look at both tunnel ends, the new tunnel portals will also receive a historical look. They are poured with Mammut panels on MEP shoring towers. Trapezoidal strips on the panel facing create a joint pattern that fully resembles the brickwork of the old portals.
Fast progress in line with the schedule
Work is done both inside and outside the tunnel tube on both tunnel ends. The new tunnel tube is planned to be operational in 2017 and travel time from Munich to Berlin will then be reduced from 6 to only 4 hours.
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