Long-term life of tunnel structures within the transport infrastructure is expected to a return of higher investment for construction. Structure of tunnel lining can be exposed to negative influences of ground water etc., which cause degradation of used materials during this long period of time. Reduction of bearing capacity is the result, which in the critical case may cause the collapse of whole structure. Thus, it is advisable to know response of the weakened structure in order to identify the negative trends in its behaviour early and to proceed with remediation. Consequences of lining degradation can be analysed, for example, by FEM (Finite Elements Method) modelling of tunnel. Analysis of utility tunnel in Brno in Czech Republic is presented in this paper as an example. The modelling dealt with the simulation of the construction process for determining the current stress conditions around the tunnel. Further, detailed modelling of sprayed concrete lining using an advanced material model was focused on. The impact on the tunnel stability was investigated by the reduction of bearing capacity of the lining. Possible degradation of the structure was simulated by reducing the thickness of the lining and the material characteristics reduction. Determination of the limit deformations for geotechnical monitoring system can be an example of outcome from the analysis. Unfavourable development of the load bearing capacity can be recognized in early states and collapse can be prevented.

tunnel lining, degradation, FEM modelling, shotcrete model