Seismic Response Characteristics of a Biased Rock Tunnel Subjected to Obliquely Incident SV Waves

Based on the viscoelastic artificial boundary theory and the equivalent seismic load input method, this study develops a three-dimensional time-domain input method for obliquely incident SV waves; the validation of this input method was verified, and seismic response analysis was conducted on a biased rock tunnel. The results indicate that the structural seismic response under oblique wave incidence differs significantly from that under vertical incidence. With an increase in the incidence angle, the tunnel’s stress, acceleration, and damage zones all tend to concentrate toward the left arch foot and waist. At different times during the earthquake, stresses and plastic zones develop at the tunnel shoulder, along with the obliquely incident seismic wave propagation, and the stresses and plastic zones gradually concentrate in the direction facing the waves, causing damage at the tunnel foot near the earthquake source. Therefore, in tunnel structures located near the epicenter of an earthquake, the damage evolution at the foot of the tunnel facing the seismic waves should garner more attention.