When the Going Gets Tough: Completely Reliable Sealings are Required

One must be able to completely rely on the efficiency of sealing systems, especially when the going gets tough. With the Katzenberg Tunnel railway project the going really did get tough.

The Katzenberg Tunnel is a railway project on the new and upgraded rail line between Karlsruhe and Basel. The two parallel, single-track tubes, which are designed for train speeds up to 250 km/h, are located between Bad Bellingen and Efringen-Kirchen. They are intended to increase the capacity and maximum train speed of the so-called Rhine Valley Railway. With a length of 9,385 m, this tunnel will be the third longest in Germany when it is opened at the end of 2012.

Investigative geological drillings have shown that the Katzenberg Tunnel runs through mainly soft rock strata such as clay, marl, limestone and sandstone formations which are highly rugged and form up to four groundwater storeys in several areas. The tunnel is situated below the mountain water level over its entire length.

Given these complicated geological conditions leaks had to be expected which could, already when planning the two tubbing tubes and a total of 18 mining crosscuts, have impeded the construction progress and affect the building structure– resulting in hardly predictable follow-up costs due to the large dimensions of such a project. Where predictable and manageable, as with the crosscut connections into which the connecting galleries between the main tubes enter, measures against water loads had already been conceived in accordance with the standard rules of engineering sciences, i.e. injection tube systems had been installed at these “interfaces”. However, leakages could alsooccurspontaneously, for instance after crack formations, in which case nobody could know in advance whether, when and where these might occur. In such an event it would have been essential to react quickly and to eliminate these leaks reliably and safely.

For sealing such cracks, the ARGE Katzenbergtunnel relied on the long-standing experience of WEBAC and commissioned us with the supply of suitable injection systems which – not only when the going gets tough – would ensure reliable sealings.

The WEBAC injection methods, which have been certified by the MPA Braunschweig material testing institute, proved their efficiency and reliability on site. WEBAC_® 1405 was used for the actual sealing process. Thanks to its excellent adhesion and flexibility,which considerably exceeds even the very high requirements stipulated in EN 1504-5, the injection resin WEBAC_® 1405, which has been tested and approved in accordance with ZTV-ING/RiLi SIB, is the ideal solution for this purpose.

The special epoxy putty WEBAC_® 4525 did the trick on the mostly wet substrates offering little stability and was successfully used as a safe and quickly stress-resistant patching to prepare and support the injection work. Thus, WEBAC is helping to ensure that the Katzenberg Tunnel can be put into operation as scheduled at the end of 2012, providing more safety and comfort to rail passengers travelling between Freiburg and the Swiss border.