Nonlinear Response of Tunnels under Coseismic Displacement Induced by Strike-Slip Fault

Abstract

In addition to seismic waves, coseismic displacement is also generated during earthquake events, which decreases gradually away from the seismogenic fault and may bring damages to tunnels in the area. This study aims to investigate the nonlinear response of tunnels under coseismic displacement induced by strike-slip fault. First, a method for applying coseismic displacement on the finite-element model (FEM) is developed by converting the displacement into equivalent nodal forces applied on the element nodes. Then, the nonlinear response of the tunnel under coseismic displacement is numerically investigated, considering the influence of the angle of the tunnel axis with respect to the fault trace, the epicentral distance, and the earthquake magnitude. The numerical results show that the tunnel might suffers tensile damages under coseismic displacement induced by the strike-slip fault, which indicates the coseismic displacement, as one kind of earthquake loads, should also be considered in seismic analysis for tunnels. Moreover, some other conclusions can be drawn: (1) The tensile deformation of the tunnel increases first and then decreases, as the tunnel axis changes from being perpendicular to the fault trace to being parallel to the fault trace, which is converse for the shear deformation; (2) the damage degree on the tunnel lining increases first and then decreases while the epicentral distance increases; (3) with an increasing earthquake magnitude, the tunnel damage increases dramatically. This study offers an insight into further research on tunnel response under coseismic displacement.