Combination of the new and patented clamping ring system as an assembly level for the statically relevant reinforcement structure in connection with spacers from BAG Bauartikel GmbH.
The tension ring system represents a precise installation level in the tunnel cross-section. Each installed ring is precisely measured on the mountain side with the help of a tunnel measurement system. In this way, the reinforcement is installed in the exact position and does not lead to under or overlay on the air side.
A self-supporting reinforcement structure is also created. In contrast to other assembly methods, e.g. With the help of supporting arches, the formwork carriage does not have to push the reinforcement into the desired position over the air-side spacers during set-up.
The precisely dimensioned reinforcement position also reduces the number of spacers to be installed. Thus, in consultation with the company Spannring GmbH and the client, BAG Bauartikel developed a spacer concept that represented a combination of the special spacers “Kreuzfix” with steel spring clips and the new special spacer “Wippe”.
Since every spacer penetrates the concrete cover, a technically sensible spacer should always be selected so that it secures the concrete cover and has the least possible formwork contact.
These claims were guaranteed by using the “Kreuzfix” spacer in the elms. Thanks to its unique shape, the “Kreuzfix” spacer has very little formwork contact and the in-situ concrete has a very good circulation.
The special spacer “seesaw” was used in the tunnel ridge. This spacer offers the advantages of a surface spacer in that it removes the reinforcement side using 2 bars and on the formwork side, comparable to a single spacer, only stands against the formwork at certain points. This also ensures that the spacer with in-situ concrete extends around the area.
By combining the tension ring system as a reinforcement gauge and the air-side spacer concept from BAG Bauartikel GmbH, approx. 9 km of inner shell on the H33 project, Brenner Base Tunnel, in Austria, was concreted without any problems. None of the concreted blocks had areas in need of renovation with regard to the concrete cover. Defects in the concrete surface, often caused by spacers, were also not visible.
Thus the overall concept of the tension ring system in connection with the special spacers from BAG Bauartikel GmbH was convincing and a complete success.