BBT is an extremely complex tunnel system. Besides the two main tubes and the exploratory tunnel, there are many connecting branches, side elements and emergency stops plus four lateral access tunnels. BBT main tubes run for about 64km (55km Brenner Base Tunnel and 9km Innsbruck bypass), making it one of the longest underground railway stretches in the world. This exceptional infrastructure represents a true engineering challenge because of its intrinsic geometrical complexity and the extreme variability of encountered rock masses. We supported the client during the selection process of the most effective TBM – the reliability of this choice guaranteed by our Digital Project Hard Rock tool to perform a statistical evaluation of the problem (based on Monte Carlo algorithm).
The design need for a collapsible backfilling brought SYSTRA SWS to review the state of the art. Expanded clay was identified as the most promising solution. Mechanical characterisation and its applicability were not well developed at that time and SYSTRA SWS set up a research project to provide the best possible solution to our clients’ needs.