Hybrid methods for shotcrete and segmental linings tunnel shells – Combining displacement and rotation measurements with computational multiscale mechanics

This contribution highlights recent developments in the analysis and monitoring of tunnel linings based on so-called hybrid methods. In this context, the word ”hybrid“ refers to a suitable combination of measurement data from geotechnical monitoring, with advanced simulation tools of engineering mechanics. The first part of this contribution refers to the New Austrian Tunneling Method (NATM), where monitoring during construction includes daily measurements of the 3D displacement vectors of ”measurement points“ installed in ”measurement cross-sections“. Shell theory-informed spatial and temporal interpolation of the displacements between the aforementioned ”grid points“, allows for reconstructing the evolution of the displacement and strain fields throughout the tunnel shell. Feeding these fields into realistic thermo-chemo-mechanical, potentially multiscale, models for the chemically hardening and creeping shotcrete, allows for the determination of the lining stresses over time. The latter give access to corresponding safety indicators or utilization degrees considering the evolving strength of shotcrete; and they also allow for quantifying the traction forces acting from the rock mass, on the exterior boundary of the tunnel lining. The second part of this contribution refers to the first steps towards the hybrid analysis of segmental lining, as installed in mechanized tunnelling. Relative rotation angles, as measured, in the course of a full-scale test, in the joints between adjacent segments of a segmental ring, are prescribed on a structural mechanics model based on analytical solutions from circular arch theory. © 2018, Wilhelm Ernst and Sohn. All rights reserved.