Study on the tunnel shape and soil-lining interaction influencing the lining behavior under seismic loading

The response of tunnels subjected to seismic loading is a complex mechanism and depends not only on the seismic nature but also on tunnel structure and surrounding soil properties. The individual behavior of circular, rectangular, and sub-rectangular tunnels subjected to seismic loadings has already been studied in the literature. In the present research, two case scenarios of circular, rectangular tunnels and four sub-rectangular shaped tunnels, with similar cross-section areas, were adopted to perform a comprehensive numerical investigation. The purpose of the study was to determine the mechanical behavior of tunnels of different shapes, depending upon seismic conditions. Analyses were performed by considering the influence of soil-lining interaction, soil parameters, and lining thickness, as well as lining rigidity. Computations were performed for no-slip and full-slip conditions. The results indicate that the tunnel shape design is of great importance when regarding the mechanical behavior of the surrounding soil. This concerns no-slip as well as full-slip soil-lining interaction, especially when the lining is subjected to seismic loading. Moreover, it is shown that changes in incremental bending moments for circular, rectangular and sub-rectangular tunnels that depend upon the soil-lining interaction conditions differ significantly.