Paierdorf ventilation facility - design and construction of a complex structure in challenging ground conditions / Das Lüftungsbauwerk Paierdorf - Planung und Herstellung eines komplexen Untertagebauwerks in anspruchsvollen Gebirgsverhältnissen

The Paierdorf ventilation facility is a part and a preparatory contract for the Koralm Tunnel KAT 3 contract, and is situated approximately 3.7 km from the western portal. It consists of a vertical 120 m deep shaft, an 88 m long expanded section of the south tunnel, access tunnel/TBM entry cavern, an approximately 100 m section in the north tunnel and a ventilation tunnel having a length of around 93 m. The shaft, the access tunnel and the top heading of the south tunnel had already been constructed during the extended exploratory programme of the Koralm Tunnel. The TBM entry cavern, the segment of the north tunnel as well as the section in the south tunnel and the ventilation tunnel were then added in 2012. The ventilation tunnel crosses over the south tunnel with a minimal separation of 2.8 m and connects to the vertical shaft.
This geometrical arrangement results in complex geometry of the underground structure and complex geotechnical interaction between the parts. This paper concentrates on the prediction of system behaviour in the design phase with 2D and 3D numerical calculations and the comparison of predicted with observed behaviour during construction.