FEM parametric analyses of the seismic behaviour of tunnel-soil-overstructure systems.

Nowadays, the urgent need to achieve high levels of environmental sustainability motivates researchers to look at solutions to solve the environmental pollution generated by road traffic, and so to improve the quality of life. Surely, tunnels represent one solution for urban areas and so they are in continuous development. In their design it is extremely important to assess the possible damage that can occur during an earthquake to the tunnel and to the aboveground structures, to provide adequate mitigation measures. Very care must be devoted to this evaluation because the presence of tunnels close to aboveground structures may modify the response of these structures, and, at the same time, the presence of aboveground structures may modify the dynamic response of tunnels. Furthermore, the dynamic properties of the soil “involved” by the aboveground and underground structures play an important role. The present paper deals with a tunnel-soil-aboveground building system, whose studies are still very few. The focus is the evaluation of the effects of the tunnel on the seismic response of the aboveground building and vice versa; this study was performed by different parametric FEM analyses. Starting from a cross-section of the recently built underground network in Catania (Italy), involving heterogenous soils and including an aboveground building, the tunnel’s depth, the aboveground building’s position, and the seismic inputs were changed, analysing their effects in terms of lining forces on the tunnel and seismic horizontal forces on the aboveground structures.