Presently, considering the magnitude of infrastructure projects with special emphasis on transportation, modelling of tunnel has gained huge significance. In analysis of Tunnels, one of the major objectives is to figure out whether it is stable for effective use for the given design and whether the construction process is adequate. In the present study NATM is used for excavation of tunnel. Initially the modelling of tunnel is carried out for two-dimensional plain strain analysis ‘2D’ as well as ‘3D’ and a comparison is done for analysis of construction stage. Further two shapes of tunnel are compared viz. ‘Circular’ and ‘Square’ for its displacements due to stress, axial force and bending. Having established the practical relevance for 3D over that of 2D, analysis for varying diameter is carried out for 3D problem only. Knowing that the Circular shape is rendered more structurally stable, further study is carried out considering only the ‘Circular’ shape for two different diameters of practical significance. The simulation/modelling is performed using MIDAS GTS Nx. Finite Element Analysis (FEA/FEM) is deployed. The parametric study undertaken is that of changing values of coefficient of Lateral earth pressure ‘K0’. Six different values of ‘K0’ are considered. The Shape and Size of the structure is altered. The study can be used by Tunnel Engineers to approach real world problems based on taking informed decisions of stress deformations to render the structure ‘safe’.