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R. Lackner, Ch. Hellmich, H.A. Mang:
"Synthesis of Constitutive Modelling and On-line Measurements for the Analysis of NATM Tunnels";
in: "Proceedings of the 3rd Congress of the Croation Society of Mechanics", P. Marovic (ed.); Croatian Society of Mechanics, Zagreb, 2000, 53 - 66.

This paper contains recent results of numerical analyses of shotcrete shells of tunnels driven according to the New Austrian Tunnelling method (NATM). These analyses are based on a {\em hybrid method}, combining realistic material modelling of shotcrete and 3D {\em in-situ} displacement measurements. Hereby, histories of displacement fields are determined from the {\em in-situ} measurements by suitable interpolation functions. They are prescribed on the outer boundary of the mechanical model of the tunnel shell. In order to obtain realistic stress states in the shell, a material model for shotcrete accounting for the changing stiffness and strength (aging) as well as for inelastic material response such as creep, shrinkage, and cracking and crushing of shotcrete is employed. On the basis of the obtained stress state, the level of loading of the shell is estimated. It amounts to 0\% for the unloaded shell and to 100 \% if the material is loaded up to the (actual) compressive strength. The efficiency of the proposed hybrid method is illustrated by means of numerical analysis of the Sieberg tunnel in Lower Austria. This tunnel constitutes a part of the high capacity railway line between Vienna and Salzburg.

Keywords: tunnel, NATM, shotcrete, hybrid method, measurements