Centrifuge modeling of seismic loading on a tunnel crossing saturated sand deposits with different relative densities

In this study, two centrifuge shaking table tests were conducted to investigate the seismic response of a shield tunnel crossing saturated sand deposits with different relative densities under bidirectional seismic excitation. The Fujian sand was used to prepare the sand deposits, and the model tunnel was made of plexiglass. The circumferential joint and bolted joint connections in the model tunnel were comprehensively considered. The experimental results highlighted the dynamic response of the tunnel lining near the soil interface. The extent of tunnel uplift and pore pressure accumulation was found to be larger in the loose sand. The acceleration responses observed in the dense and loose sand deposits differed. The bending moments in the tunnel lining exhibited noticeable oscillations at the tunnel shoulder and haunch. The shear deformation of the circumferential joint was prominent at the tunnel shoulder and haunch, while the normal displacement of the circumferential joint was prominent at the tunnel crown and invert. Thus, the seismic deformation mechanism of the tunnel crossing sand deposits with different densities was analyzed.