Untersuchungen und Maßnahmen zur Reduzierung des versinterungsbedingten Wartungsaufwandes am Saukopftunnel

The Saukopftunnel breaks through the mountain ridge of the Odenwald main ridge below the Saukopf (348m above sea level) in a length of 2,714m with overburdens of 10m to 180m. Because of the existing geology as well as the present hydro geological conditions the first 1950m were carried out drained with open invert and the remaining 765m sealed with invert arch. Although no indications of a possible risk of scale deposit were found within the scope of the project phase with non-weathered granodiorit and underground water which was poor of lime, very thick deposits appeared already early in the drainage system. These deposits required a flushing each four to six weeks. The target of the examinations at the drainage system of the Saukopftunnel was to test if a reduction of the extreme tendency of scale deposit could be made possible by suitable measures. On the basis of the promising results of the examination structural measures to modify the drainage system were proposed which were expected to considerably reduce the great scope of maintenance at the Saukopftunnel by a comparative small expenditure. The effects of the reconstruction at the drainage system show a visible improved scale deposit reaction so that a maintenance interval of three to four months could be observed after the opening of the Saukopftunnel. In comparison with the year 1998 a reduction of the maintenance works caused by scale deposit of 77% could be achieved by the examinations and the modification of the tunnel drainages. In all more attention has to be given to the drainages in the future than it is the case today. The drainage is an important factor for the operation of a tunnel. This is why the drainage has to be included in the entire construction of a tunnel and cannot be treated as a minor appendage anymore.