The effect of geometry on the structural analysis in the circular and square formed underground stations

Metro lines, which are one of the indispensable parts of transportation nowadays, provide great convenience for users. As a result of population growth and migration, the investments made in this direction are increasing also in our country. Stations, tunnels, shafts, and outlet structures to be constructed within the scope of project processes are designed by determining the functional requirements. Station designs are made in line with the expropriation needs of the region, architectural and electromechanical requirements, therefore, structures with different geometries may emerge in this context. In this study, the structural behaviors of two underground station structures in the form of a circle and a square with the equivalent cross-sectional area and same height, which can meet the same functional requirements, are compared. Two station structures with the same ground conditions and excavation depth, but different geometry, were dimensioned with similar openings in the plan plane. The pre-sized station structures were modeled using the Plaxis 3D software, and the structural system behavior of two different structures was investigated. The displacement and internal force values of both structures in static and dynamic conditions were examined. The analysis results of the structures modelled using finite element method have revealed that the displacement and internal force values in the static and dynamic stage of the station structure with circular geometry can be less than the square formed station structure due to the arching effect.