Analysis of tunnel behaviour under seismic loads: the role of soil constitutive assumptions

In this paper a set of 2D FEM analyses of tunnel behaviour during seismic loading is presented using a traditional and a more advanced numerical approaches. The numerical analyses, carried out under plane strain conditions, are aimed at establishing the relevance of the different constitutive assumptions on the computed ground deformation and loads acting in the transversal section of the tunnel lining during the seismic wave propagation. The behaviour of the soil is described, in one case, by a linear visco-elastic model, and, in a second case, by a plasticity model capable of describing early development of non-linearity, memory of stress history, anisotropy and the effects of structure and its degradation with plastic straining. Special emphasis is given to the description of the calibration procedure for the material parameters and the initialisation of state variables in correlation to the geotechnical characterization of the soil deposit.