Development of holistic prognosis models using exploration techniques and seismic prediction

As part of the Brenner Base Tunnel project, the currently running Tulfes‐Pfons construction lot includes a stretch of the exploratory tunnel (ET), which has a length of 15 km and is being bored by a gripper TBM. During this tunnelling work, a diverse and broad set of exploration techniques is being used. Although it is an exploratory tunnel, the tunnel is subject to the same constraints as a performance heading. The choice of exploration techniques was made with regard of the capability to smoothly integrate them into regular tunnelling in order to not create further downtime. The exploration techniques are useful for the current ET but also to produce a forecast for the subsequent main tunnels (MT). The geological investigation is undertaken by face and peripheral mapping as well as by percussion drilling ahead of the machine. The geotechnical exploration is carried out by analysing the TBM parameters and the system behaviour, and analysing the percussion drilling. The exploration concept is completed with the geophysical reflection seismic method. All these exploration methods have different sensitivities, exploration ranges and directions, strengths and weaknesses, so they complement one another. This paper assesses the exploration techniques based on the experience until now. A case study of one fault zone is presented to show how the different exploration methods interact and contribute to a holistic prognosis model.