Die Bohr‐ und Injektionsarbeiten des Bauloses SBT 1.1 – Tunnel Gloggnitz

Abstract

The Semmering Base Tunnel (SBT), which has a total length of 27.3 km, is one of the most important construction projects in the Baltic‐Adriatic railway corridor. The base tunnel crosses the foothills of the Eastern Alps and connects the two federal states of Lower Austria and Styria. Due to the complex rock conditions, extensive and novel grouting systems are used. The primary target of the grouting is to reduce the permeability of the rocks and reduce the water entry (peak water ingress in the tunnelling area up to 300 l/s), as well as to improve the rock mass strength in some parts. Based on the grouting design, specific drilling and grouting procedures with various grouting materials were developed for sealing and tempering the water‐bearing areas of Grassberg and Otterstock. Innovations include the development of a standpipe packer and a cased grouting‐pipe system with grouting valves to prevent erosion along the drilling line for use in unstable borehole conditions. The combined cement/polyurethane suspension (hybrid grout) allows an extended economical use of cement suspensions.