Seismic Response of Tunnels Under Effect of Overburden Depth Using Simplified Pseudo-Static Analysis
Authors:   Civil Engineering Programme, Department of Civil Engineering, Faculty of Engineering, Universiti Pertahanan Nasional Malaysia Kem Sungai Besi, 57000, Kuala Lumpur, Malaysia, Fazully Faizzuan , Che Osmi Siti Khadijah ,   Civil Engineering Programme, Department of Civil Engineering, Faculty of Engineering, Universiti Pertahanan Nasional Malaysia Kem Sungai Besi, 57000, Kuala Lumpur, Malaysia, Othman Maidiana ,   Civil Engineering Programme, Department of Civil Engineering, Faculty of Engineering, Universiti Pertahanan Nasional Malaysia Kem Sungai Besi, 57000, Kuala Lumpur, Malaysia, Hafizi Nursyafikah ,   Civil Engineering Programme, Department of Civil Engineering, Faculty of Engineering, Universiti Pertahanan Nasional Malaysia Kem Sungai Besi, 57000, Kuala Lumpur, Malaysia
Published: January 2025

Earthquakes are one of the natural occurrences that can lead to massive disasters, either on structures or infrastructure. The seismic response and performance of underground infrastructure such as tunnels against earthquake vibrations is predictably severe due to the complex interaction between tunnels and the surrounding soil, especially one embedded in poor soil material properties. In view of this, previous experiences of tunnel damages
subjected to earthquake loads have been reported in the literature. Thus, rigorous analysis is necessary to provide indepth knowledge and understanding of the seismic response of tunnels which beneficial to engineering practitioners in especially in early design stage in order to avoid the future risk of tunnel damage and failure during an unpredictable earthquake event. The aim of this study is to investigate the effect of overburden depth on seismic response of tunnels using the simplified pseudo-static analysis, while simultaneously to emphasize the shortcoming of conventional closed-form solution. This study presents a two-dimensional (2D) simplified pseudo-static analysis of soil-tunnel model embeded at 10m and 20m overburden depth subjected to increasing levels of seismic intensity at the transverse direction of tunnel axis. The numerical investigation was performed using the finite element program PLAXIS 2D. The circular shaped tunnel lining are assumed to be elastic, while the soil is considered as homogeneous, and isotropic in plane strain condition. Considering the complex soil-tunnel interaction, the tunnel lining and soil interface is assumed as no-slip condition. The numerical result of pseudo-static analyses were compared with the conventional closed-form Wang‘s analytical solution to verify the reliability of the obtained results. The results denoted that the tunnel embedded at 10m overburden depth experienced considerable seismic-induced deformation and structural forces than tunnel buried at 20m depth. The deformation and seismic induced structural forces of tunnel increased with increment on the magnitude of earthquake loadings. Thus, it can be concluded that the shallow tunnel suffered more damages compared to the tunnel embedded at deeper depth. Overburden depth of tunnel plays a significant role in modifying the seismic response of tunnel apart of the imposed magnitude of earthquake loadings. The conventional closed-form analytical method tends to overestimate the seismic response of tunnel compared to numerical pseudo-static analysis.