The behavior of underground structures under seismic effects is more influenced by the displacement of the soil-structure environment than by the inertial forces resulting from ground motion accelerations. During an earthquake, underground structures tend to follow the displacements occurring in the surrounding soil. Therefore, displacement-based design approaches should be adopted in the design of underground structures. During an earthquake, tunnels undergo axial and bending deformations in the longitudinal direction (parallel to the tunnel axis) due to the propagation of seismic waves, while in the transverse direction, they are subjected to ovaling/racking deformations, particularly due to vertically propagating S-waves. Within the scope of this study, seismic analyses were conducted for circular-section TBM tunnels. Numerical analyses were carried out using the Plaxis 2D software. Displacement values obtained from two different calculation approaches were applied to the model, and resulting ovaling deformation values, bending moments, and axial forces in the tunnel lining were obtained. The results from the two different analysis methods are presented comparatively.