The excursion on 08.11.2022 took the staff of the Institute of Geotechnical Engineering once again to the U2 Matzleinsdorfer Platz construction site, where we were given the opportunity to find out about the progress of construction and to inspect the excavation work for the second tunnel tube under the protection of an icing shield.

In the course of the extension of the underground line U2 in the direction of Wienerberg, the starting shaft for the two tunnel tubes is being built at Matzleinsdorfer Platz in addition to a new station. To the south of Matzleinsdorfer Platz, a 30m deep shaft was constructed for this purpose in the Triester Straße area. A second shaft was constructed north of Matzleinsdorfer Platz in the area of Margaretengürtel.

Inner-city tunnelling is always associated with extensive additional measures, which are primarily intended to reduce subsidence to a minimum. In order to improve the settlement behaviour during the mining undercutting of the belt and to secure the subsoil in advance, the tunnelling of the calotte takes place under the protection of a subsoil freezing. For this purpose, an icing shield was created by means of brine icing before the driving work began. After the construction of the two shafts and the icing shield, the driving of the tunnel tubes is currently taking place under the protection of the icing.

After a short safety briefing, our employees were welcomed by DI Hornich, DI Yoshida and Ing. Harder and led in smaller groups down the 30 m deep shaft to the icy face, where the driving work was in full swing. In this section, the heading is carried out cyclically as a spherical heading (incl. support core). The tunnel tubes are excavated in sections of about one metre. Due to the icy ground, excavation at the tunnel face is carried out using a milling machine.

Many thanks to DI Wolfgang Hornich, DI Matthias Yoshida and Ing. Daniel Harder for this exciting and extraordinary excursion to the construction site!