Weiterentwicklung von Stauchelementen und Spritzbetonanschlüssen

Yielding elements in combination with shotcrete linings are used in Austria since 1994, replacing the previous method of leaving open gaps. The first system, used at the Galgenbergtunnel, consisted of groups of axially loaded steel pipes with manufactured local weakness. The resistance of those elements showed a pronounced oscillation during shortening. This triggered a first improvement of the elements in the late 1990ies. Those elements were called LSC (Lining Stress Controller) and subsequently successfully used on a significant number of projects around the world. Recently, the yielding elements have been further optimized aiming at easier production and lower costs. Still using steel pipes, those are filled with porous material, increasing the elements' capacity. With sequential excavation, construction joints in the shotcrete lining are necessary. Producing quality joints appears to be difficult without special connecting elements. The so produced connections are thus potential points of weakness, reducing the lining capacity. A prototype of a connecting element was developed, which can be easily produced and installed. Site tests have been successfully conducted at the tunnel Stein in Austria.