Mechanical response of highway tunnels under fault dislocation and a combined anti-dislocation technology: a case study of the Tianshan-Shengli Tunnel

Active faults are widely distributed in China, posing a significant threat to the safe operation of tunnels. Current research on anti-dislocation technologies for tunnels has predominantly focused on either articulated designs or over-excavation individually, with limited studies investigating the tunnel response and anti-dislocation performance under the combined effect of both. Therefore, based on a highway tunnel crossing an active fault, the deformation and failure characteristics of the tunnel subjected to fault dislocation are first revealed. Subsequently, following a segmented prevention strategy, a combined anti-dislocation scheme integrating over-excavation and articulated designs is proposed. Finally, the influence of this combined technology on the tunnel response and its disaster mitigation effect are investigated. The results indicate that under fault dislocation, the tunnel lining exhibits an S-shaped bending deformation along the longitudinal direction. Lining failure initiates at the fault plane and then propagates outward, primarily manifesting as shear-bending failure. It is recommended that critical prevention measures be adopted within approximately 30 m on both sides of the fault plane, while general anti-dislocation measures should be applied within a zone of approximately 70 m on each side. A specific combined anti-dislocation scheme is proposed, detailing the structural configurations of the measures. The combined technology effectively reduces the severity of lining deformation, improves the lining’s stress state, and consequently mitigates lining failure, demonstrating good disaster mitigation effects. This combined anti-dislocation technology has been successfully implemented in the engineering project, providing a reference for the anti-dislocation design of tunnels traversing active faults.