Application of a new shotcrete constitutive model to the numerical analysis of a tunnel excavation

Numerical analyses are performed on a routine basis in practical geotechnical engineering to assess the deformation behaviour of tunnels - in particular, for near-surface tunnels - in soils where the influence on existing infrastructure (such as buildings, deep foundations and adjacent tunnels) has to be evaluated. In addition, it becomes increasingly common to use results from numerical analysis as basis for designing the support measures for the tunnel. When doing so, the strongly nonlinear material behaviour of shotcrete - namely, the increase of stiffness and strength with time - should be taken into account, in particular when the excavated cross-section is subdivided into several construction stages involving temporary shotcrete structures with high stress concentrations near corners. In this paper, a new constitutive model for shotcrete is applied in the numerical analysis of a complex underground railway station. It could be shown that significant differences in lining stresses are obtained when employing the newly developed constitutive model for shotcrete. However, the overall deformation behaviour is not significantly influenced by the shotcrete model.