The Tunnel Oberau, with a length of 2.9 km, forms the core of the local bypass of Oberau. Between the two massifs Kirchbichl and Muhlberg, the tunnel is situated in the valley of the Gie ss enbach in alluvial gravel with only a small overlap underneath settlement-sensitive buildings. In this paper, the measures in the tunnel to minimize the settlements of the buildings during the shotcrete excavations are described. Basis for this planning were extensive 3D-FE-calculations. Furthermore, under two buildings a compensation grouting measure was carried out, in order to compensate the occurring settlements. This paper describes how the required time and the amount of injection material (grout) could be reduced during the compensation grouting in highly permeable gravel.
