Numerical Evaluation of Seismic Performance of Concrete Tunnels Considering Concrete Liner Parameters

Abstract

The tunnel form concrete system is a new industrial construction method to facilitate construction management and reduce construction time and related financial risks. Unlike conventional framed structures, this system does not have columns and beams. However, the wall and slab elements resist lateral and gravity loads. One of the most important factors producing axial forces, shear forces, and bending moments in concrete tunnels is earthquakes. Tunnels are inherently stronger than structures on the ground. Earthquake damage in different regions of the world has highlighted the importance of creating dynamic loads in the design of concrete tunnels. This study aims to numerically evaluate the seismic performance of concrete tunnels considering soil-structure interaction. The main innovation of this research is the comparison of numerical results with analytical methods and results. According to studies, although analytical methods may provide responses, often the responses are too long and difficult or it is impossible to measure the dynamic load in tunnels accurately. As a result, numerical methods are used to investigate the seismic performance of concrete tunnels by considering soil-structure interaction. To implement numerical methods, FLAC3D software is used to model the behavior of structures built in rock and soil. The main advantage of numerical methods over analytical methods is the continuous concrete liner. According to the results, increasing the bending moment deformation modulus leads to a decrease in the axial force in the concrete tunnel liner. Subsequently, strengthening the thickness of the tunnel concrete liner leads to an increase in the bending moment. Finally, increasing the number of concrete liner pieces leads to a decrease in the maximum axial force and shear force.