Shaking table tests on deformation pattern and failure mechanism of fault-crossing tunnels in non-rupture scenario

Tunnels, as critical underground infrastructures, often intersect with faults. Field investigations have underscored the susceptibility of fault-crossing tunnels to extensive damages during earthquakes. Hence, large-scale shaking table tests are conducted to investigate the deformation pattern and failure mechanism of fault-crossing tunnels under transverse excitation, particularly in non-rupture scenarios. The dynamic behavior of the tunnel, as expected, is dominated by the surrounding strata. Acceleration responses vary notably across different regions of the fault site. The disparity increases with the increments of seismic intensity and input frequency. The tunnel section at the interface between the fault and the hanging wall manifest the strongest acceleration, where the largest strains of the tunnel and most of the lining cracks also occur, highlighting its vulnerability to seismic vibrations. The damage-induced non-linearity of the tunnel is then identified by the decreasing dominant frequency thereof. The fault-crossing tunnel exhibits unique three-dimensional shearing-torsional deformations, elucidated through the test data and an analytical model. This deformation pattern provides a better understanding of the seismic responses of fault-crossing tunnels under seismic vibrations.