ABSTRACT
Factors such as global warming contribute to noticeable fluctuations in groundwater levels significantly affecting the stability and safety of underground structures. In an earthquake scenario, sand deposits prone to liquefaction experience a sudden increase in pore water pressure during strong ground motion, leading to significant soil layer deformations. This increase in excess pore water pressure can cause uplift or floatation of the structure compromising the safety, structural integrity and stability of the underground structures, such as large vehicular tunnels, metro stations etc. Therefore, studying shallow rectangular tunnel embedded in saturated sand prone to liquefaction and subjected to changes in groundwater level under seismic loading is critical. This study focuses on the numerical analysis of a shallow rectangular tunnel under plane strain condition using PLAXIS 2D software. The advanced constitutive model PM4Sand, capable of capturing the nonlinearity of the soil in a solid-fluid coupled analysis, is employed. The uplift displacements of the substructure embedded in Hostun sand are analysed by varying the groundwater level, width of the tunnel and the aspect ratio (H/B), which is the height-to-width ratio of the rectangular tunnel. The (H/B) ratios are assumed to be 0.3, 0.5, and 1. The results obtained provide insights into optimizing tunnel design to mitigate risks associated with liquefaction and seismic loading. Hence, this study aims to provide a comprehensive understanding of the interactions between soil and tunnel in liquefiable conditions, ultimately contributing to the design of safer and more resilient tunnels.
