The realistic assessment of the load-bearing capacity of shotcrete linings becomes necessary a) for early and large deformations in deep tunnels, b) for single lined permanent shotcrete supports and c) for the assessment of the load-bearing capacity of shotcrete structures subsequently stressed by nearby tunnel excavations. The nowadays used linear-elastic models of primary linings using a hypothetical shotcrete stiffness are not accurate enough.

This contribution presents a more detailed determination of the load-bearing capacity of the primary shotcrete lining. It captures the time-dependence of the loading history and of the shotcrete properties. The capability of this approach is shown by the back analysis of a deep tunnel section with an advanced shotcrete material model. The material parameters of the young shotcrete have been calibrated based on uniaxial tests on specimens gained during construction. The back analysis presented here combines the advanced material model with a new testing approach.