ABSTRACT
All the underground infrastructures require important financial investment and if they are not adequately maintained could produce more costly and extensive repairs of tunnels. The standardisation of maintenance strategy usually foreseen for serviceability and safety reasons can reduce the life cycle maintenance cost ensuring the requested level of structural safety.
In the first part an integrated process starting from the preparation phase and using an integrated approach with traditional inspection in field and digital inspection developed to define the tunnel status assessment applying statistical analysis and numerical evaluations is described.
In the second part the selection of the most effective maintenance methods using a standardized workflow is explained to reduce the maintenance costs and to guarantee tunnel safety maximizing the quality of the tunnel repairs in presence of structural degradation. Different methods commonly applied in Switzerland are summarised and particularly the applied “Standard Construction Method” of Rhaetian Railways (UNESCO World Heritage Sites) is described.
