Auberg Tunnel: Design and Dimensioning of UnreinforcedConstruction Joints between Invert and Vault

At the Auberg Tunnel in Bavaria, Germany, the connection reinforcement between the tunnel invert and the vault constructed later above it was skipped (Fig. 1). The arrangement of an unreinforced construction joint offers constructional and structural advantages compared to the design with connection reinforcement. This has a positive effect on the construction time and costs, but also influences the load-bearing behaviour of the structure, since the full moment-bearing effect of the reinforced concrete cross-section is no longer available in the joint area. The moment transferred depends on the normal forces, which are simultaneously present. In order to be able to assess the effects of dispensing with the reinforcement, the load-bearing behaviour in the joint was modelled using a spring model in the static calculations for the Auberg Tunnel [1]. This simulates the stresses and deformations occurring in the joint in accordance with the current standards and thus allows realistic statements about the distribution of the internal forces and moments in the entire structure.