Geotechnical rock mass characterisation and classification at the Brenner Base Tunnel project – Methodology and solutions.

For the construction of the Brenner Base Tunnel with a total length of the whole tunnel system of 230 km, the geotechnical characterisation of the rock and the rock mass based on the geological mapping, the exploration and the geological models is of essential importance. The reliability of the ground prediction and consequently the effectiveness of the construction and support measures are mainly influenced by the methodology for the evaluation of the characteristic material parameters of the ground. This mainly influences the project process and the construction as well as the maintenance costs of a tunnelling project. In this paper, the applied methodology with its approaches of resolution for the improvement of the reliability of the ground prediction at the Brenner Base Tunnel project are explained in detail. Furthermore the improvements to this methodology during different project stages are shown. The paper concentrates on the implementation of the results gained from the exploratory tunnel and the influence of these results on the methodology for the improvement of ground prediction and the reduction of ground risks. In addition problems and approaches for solving these problems are explained in detail. For instance the avoidance of the double consideration of the influence of schistosity by using a rock mass classification system for rock mass parameter identification. [ABSTRACT FROM AUTHOR]