The Comparison of Numerical and Analytical Methods of Concrete Tunnel Seismic Performance Considering to the Interaction of Structure and Soil

One of the new methods of industrial construction is the tunnel concrete structural system which makes the issues related to the construction process easier, It also reduces construction time and financial risks. One of the most important factors that cause axial and shear forces and even bending moment in concrete tunnels is the existence of an earthquake. The purpose of the present paper is to compare numerically and analytically the seismic performance of the concrete tunnel with regard to the interaction between the soil and the structure. This research wants to say that although analytical methods may eventually reach the answer, but in most cases, either the answers are very long and difficult, or we may not be able to measure the dynamic load correctly in the tunnels. So, in order to investigate the seismic performance of the concrete tunnel, taking into account the interaction between the soil and the structure, we use numerical methods. For this purpose, using numerical methods in this treatise, we use FLAC3D software in order to model the behavior of structures built in rock and soil. The main advantage of the numerical method of the current paper compared to other analytical methods is that it shows continuous maintenance coverage. In the analyses of the present research, types of coarse-grained sandy, sandy-grained and fine-grained soils were used so that a relatively complete range of soil types was considered. In addition to these, in order to investigate the effect of density, various types of soils with high density and low density were used. Also, the number of concrete pieces with continuous concrete coating - that is, 3, 5 and 7 pieces - was checked. Here, the results showed that by increasing the modulus of deformation of the bending moment value, the amount of axial force in the tunnel's concrete cover decreased. And on the contrary, the amount of force increases. Now, if we want to show the thickness of the tunnel maintenance cover more, we will face an increase in the amount of bending moment. Finally, if we want to increase the number of concrete parts of the maintenance cover, then the amount of axial force and maximum shear force will decrease.