Evaluation of the Mechanical Response of Tunnel Lining Induced by Reverse Faulting Using Numerical Simulations

Underground structures are inseparable components of public transportation and infrastructure networks that are vulnerable to interaction with fault rupture. To address some of the practical concerns, a series of 3D nonlinear finite element models were conducted and the effects of the tunnel cross-section shape, surcharge loads, and faulting angle on the mechanical response of linings were widely investigated. The geological aspect of the problem was also considered by modeling a fault line in both parallel and perpendicular positions to the tunnel cross-section. Axial forces, bending moments, and rotation of tunnels subjected to reverse faulting in different vertical fault throws were recorded and discussed. The outcomes from the numerical simulations elaborated that developed axial forces in the lining parallel to the fault line may differ by more than 200% by changing the tunnel shape from a circular shape to a horseshoe or square structure. The ratio of forces induced by the faulting to the static loads of lining ranged from 1.5 to 6 times based on the tunnel shape, the rigidity of the tunnel as well as the dimension of the tunnel. It can be inferred from the results that the response of tunnels subjected to fault dislocation depends on various parameters that should be considered by verified numerical simulations to predict precise responses for proposing practical solutions.