Numerical study of segmental tunnel lining behavior during mechanized tunneling

During mechanized tunneling, the surrounding soil and the tunnel lining undergo a continuous changing of their state of stress and strain before reaching an equilibrium condition when the front of excavation is far enough not to induce any further effect. The impact of the construction process on the lining behavior has been investigated in this work by numerical modelling. The influence of several aspects was considered, such as the grouting pressure, the grout consolidation, the shield tapering, the segmental layout of the lining and the jacking forces. The numerical results are shown in the paper and discussed also in the light of measurements recorded during tunnel construction for a metro line.