Damage and failure analysis of twin tunnels with cross passages subjected to strike-slip faulting

• The cross passage leads to the tunnels being more vulnerable to faulting. • The cross passage is under compression and twisted during faulting. • Stress level and cross passage location affect the structure’s behaviors. Many transportation tunnels are twin tunnels with cross passages. Plenty of research has investigated the responses of a single tunnel under fault deformation. However, few studies have paid attention to the behaviors of twin tunnels with cross passages in the fault zones. The study conducts three-dimensional numerical modeling to analyze the damage and failure of twin tunnels with cross passages subjected to strike-slip faulting. The responses of twin tunnels with and without a cross passage are compared. Besides, some influence factors are discussed, such as lateral stress coefficient, location of the cross passage, and length of the cross passage. The results show that the cross passage has great effects on twin tunnels’ behaviors. The cross passage leads to the twin tunnels being more vulnerable to fault deformation. The connection section of tunnels and the cross passage rather than the fault plane sections is the most dangerous section, where both peak compressive and tensile damage are induced. The cross passage is under compression and twisted during faulting. A larger lateral stress coefficient leads to more severe damage to the tunnels and the cross passage. Both the tunnels and the cross passage become safer when the cross passage is located out of the fault. The length of the cross passage has limited effects on the behaviors of structures.