The characteristics of the two-component grout on the stress-state in segmental lining

In this work, the effective influence of the mechanical characteristics of the filling material on the safety factors of the support system is analyzed. Through an extensive parametric analysis, developed by adopting proven analytical methods, on 243 different cases of tunnels excavated using a TBM in a soil mass, at different depths and with different excavation radii, it was possible to identify the conditions in which the safety factors can be effectively low. In all these cases, therefore, it is necessary to intervene on the mechanical characteristics of the filling material, requiring elastic modules and strengths such as to guarantee higher values of the safety factors, avoiding risks on the possible failure of the concrete that makes up the segmental lining and of the same filling material that connects the support system to the tunnel wall.