Semnan University Press Journal of Transportation Infrastructure Engineering 2423-5350 5 4 2019 12 22 Numerical study on interaction of normal fault with underground tunnels Numerical study on interaction of normal fault with underground tunnels 1 12 4043 10.22075/jtie.2019.18738.1416 FA Sadegh Ghavami School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran Alireza Saeedi Azizkandi School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran Mohammad Hasan Baziar School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran Hamid Jahanbakhsh Dept. of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran Journal Article 2019 09 19 In many cases, tunnels that are considered critical underground infrastructure for urban transportation are built in high seismicity areas and active fault zones. Fault displacements during earthquakes may interact with sub-surface structures leading destructions. Recent earthquakes, such as the 1999 earthquakes in Turkey and Taiwan, revealed that by avoiding construction in the fault zone, the structures are not completely safe for fault threats. Therefore, it is necessary to evaluate the interaction mechanism between structures and fault rupture for effective design to reduce the hazards associated with surface faulting. Verified finite element modeling is used in this study to investigate normal fault-tunnel interaction. The effect of different parameters such as horizontal tunnel distance relative to rupture path in free field condition, tunnel depth, tunnel rigidity, and fault angle on fault–tunnel interaction are studied. The results indicated that the tunneling in the path of fault rupture causes a diversion of rupture path. The burial depth of the tunnel and its diameter are effective parameters in the propagation of the shear zone in the sand layer and surface deformations. With increasing the tunnel depth, the rupture path inclines more, and the shear zone is extended over a wider area. Comparison of numerical results demonstrated that surface displacement in normal fault of dip angle 45° is higher than 60°. In many cases, tunnels that are considered critical underground infrastructure for urban transportation are built in high seismicity areas and active fault zones. Fault displacements during earthquakes may interact with sub-surface structures leading destructions. Recent earthquakes, such as the 1999 earthquakes in Turkey and Taiwan, revealed that by avoiding construction in the fault zone, the structures are not completely safe for fault threats. Therefore, it is necessary to evaluate the interaction mechanism between structures and fault rupture for effective design to reduce the hazards associated with surface faulting. Verified finite element modeling is used in this study to investigate normal fault-tunnel interaction. The effect of different parameters such as horizontal tunnel distance relative to rupture path in free field condition, tunnel depth, tunnel rigidity, and fault angle on fault–tunnel interaction are studied. The results indicated that the tunneling in the path of fault rupture causes a diversion of rupture path. The burial depth of the tunnel and its diameter are effective parameters in the propagation of the shear zone in the sand layer and surface deformations. With increasing the tunnel depth, the rupture path inclines more, and the shear zone is extended over a wider area. Comparison of numerical results demonstrated that surface displacement in normal fault of dip angle 45° is higher than 60°. https://jtie.semnan.ac.ir/article_4043_376089010c1de9e5591c157893ef0575.pdf