Centrifuge Modeling of the Seismic Response of Lining Earth-Pressure Distribution and Uplift Mechanisms for Tunnels in Sand

Earth pressure on tunnel linings is a critical mechanical factor for the design, construction, and safety assessment of tunnels. However, the impact of burial depth and seismic loading on the distribution and nonlinear variation of earth pressure remains insufficiently explored. This study presents a series of centrifuge model tests on tunnels in sand at different burial depths, comparing the distribution and variation of lining pressure under centrifuge scaling. The tests reveal how seismic loading influences earth pressure distribution, emphasizing soil-structure interaction, uplift mechanisms, and dynamic behavior at varying depths. The key findings are as follows:1) Under static loading, the lining pressure of shallow and deep-buried tunnels exhibits butterfly-shaped and tortoise-shell-shaped distributions, respectively; the largest and smallest pressures occur at the lower springline and the crown. Two code-based calculation approaches predict pressures that increase linearly with depth, whereas the measurements are nonlinear; overall, the code methods are conservative. 2) Under dynamic loading, the lining pressure redistributes: shallow-buried tunnels retain a butterfly-shaped pattern, while deep-buried tunnels develop a four-pointed-star pattern. For shallow-buried tunnels, the upper springline shows the greatest increase and the crown the least; for deep-buried tunnels, the upper shoulder exhibits the greatest increase and the waist the least. 3) Under 0.1g, 0.3g El-Centro, and 0.1g sinusoidal loads, the pressure increases at various tunnel locations. In both shallow and deep tunnels, significant pressure growth occurs at the tunnel floor and lower shoulder, respectively. Standard method calculations remain conservative. After multiple seismic events, the tunnel’s operational safety and life cycle assessment remain crucial. 4) Under a 0.3g sinusoidal load, some uplift and relative motion between soil and structure are observed. In the shallow tunnel, all sections except the waist show negative pressure growth, likely due to buoyancy uplift. In the deep tunnel, the lower shoulder exhibits negative pressure growth, while the rest show positive growth, attributed to dynamic coupling and compression.