Tunnel–ground interaction analysis: discrete beam–spring vs. continuous FE model

For the purpose of studying the soil–tunnel structure interaction, a number of two-dimensional linear numerical analyses has been performed with the aid of the software package ANSYS. The present study employs both discrete beam–spring and continuous FE models, in order to estimate their ability to simulate the soil–structure interaction effects. Since these effects are particularly pronounced during seismic events, the main attention has been focused on dynamic analyses. The earthquake loading is simulated under pure shear conditions and determined by the one-dimensional free-field ground response analysis using the code EERA. Results obtained by simplified dynamic analyses are compared with state-of-practice closed-form elastic solutions and significant factors influencing the tunnel–ground interaction are evaluated. In addition, with the author’s aim to develop more realistic and relevant models, effects of initial static conditions are also considered in the analyses.