Dynamic and Static Analysis of Circular Tunnel with Special Focus on the Hydro-Mechanical Coupling Behavior of Soil

One of the most important parts of a tunnel are the supporting systems, which must be sufficiently resistant to loads during the life of the structure. Critical loads on the tunnel support system are ground and water loads, that are usually calculated separately by analytical methods.These loads have coupled hydro-mechanical behavior in the materials around the tunnel and their effects on the structure should be considered as a connection phenomenon. Therefore, in this study, using two-dimensional finite difference method in FLAC software, a static design of the tunnel was performed, in which the water was initially considered only as the pore pressure, and subsequently, static analysis was carried out completely in the form of coupling. One of the twin tunnels of Tabriz Metro Line 1 was used as a case study. For these two states, axial force and bending moment were evaluated and compared. In order to investigate the tunnel behavior under dynamic load, the real Duzce earthquake at the MCE level was selected. The axial force and bending moment in pure dynamic state and hydrodynamic coupling using Byron behavioral model were evaluated. The results showed that in the static coupled design, higher axial force of about 27% and lower bending moment of about 36% were obtained compared to the no-coupled mode. Also in the dynamic coupled design, more axial force and lower bending moment, about 25% and 66% respectively, were seen. Therefore, it can be concluded that it is best to use this state of structural loading for the detailed design of reinforced concrete structures.