Seismic Analysis of the Surface in the Presence of Underground Lined Tunnel Subjected to vertical incident P/SV & SH-Waves: A Comparative Study.

In this paper, the seismic response of the surface in the presence of a circular underground lined tunnel subjected to vertical incident P/SV and SH-waves were obtained. In this regard, the three-dimensional (3D) finite element method (FEM) approach in the framework of ABAQUS numerical software was used for preparing the model. At first, a brief presentation of FEM formulation as well as solving a validation example was carried out. Then, by considering some key parameters such as tunnel depth, and the impedance ratio of the lining, the response of the ground surface was sensitized. In the following, a comparative study was performed between the responses of 3D-FEM and 2D half-plane boundary element method (2D-BEM). The results showed that the mentioned parameters are very effective in the formation of different patterns of ground motion. Furthermore, a slight increase of amplitudes is observed in the responses of the 3D approach compared to 2D modeling. The results of the present study can be used to complete the accuracy of existing seismic codes around the subject of micro-zonation of the site in the presence of subsurface openings as well.