Structural monitoring of segmental tunnel linings: Toward safer and more resource-efficient tunnels

Shield-driven tunnels play a key role in an efficient and clean future mobility. In order to ensure their reliable operation and to allow further innovations, it is necessary to know their level of safety from a structural point of view. Only if the internal forces within the tunnel linings are known precisely, a realistic estimation of the load-bearing capacity is possible. However, this is easier said than done, as the prediction of internal forces is subjected to major uncertainties. In case of shield-driven tunnels in particular, there is still a great need for research on the prediction of internal forces. Therefore, in a current research project the authors are performing an in-situ structural monitoring on segmental tunnel linings in Frankfurt (Main) to observe the development of the internal forces. A sophisticated monitoring concept, as well as an extensive calibration and validation program, ensures reliable results. This article presents the current status of the project including the general concepts, theoretical aspects, calibration tests in the tunnel segment testing rig as well as first in situ measurement data.