Modeling of vibrations induced in tunnels: a 2.5D FEM-PML approach

The simulation and study of problems related with vibrations induced by railway traffic in tunnels is a difficult and complex task. The semi-indefined character of the domain surrounding the tunnel associated to the 3-dimensional characteristics of the problem are the major causes of that complexity. An efficient and accurate solution for the simulation of the dynamic behavior of very long structures, i.e., railways or tunnels, is proposed by using 2.5D techniques in the context of the finite elements method, and adopting PML’s for the treatment of the boundaries due to the truncation of the finite elements mesh. Since the resource to 2.5D FEM-PML approach is not very usual, the equations of the 2.5D PML are derived, highlighting the compatibility with the 2.5D FEM. After that brief presentation of the model, a range of validation examples are depicted, showing the accuracy of the model. Finally, a parametric study is presented in order to evaluate the influence of some tunnel and ground properties in the vibrations assessed at the ground surface.