Investigation of the Longitudinal Mechanical Response of Pipeline or Tunnel Under Reverse Fault Dislocation

To investigate the longitudinal mechanical response of a pipeline or tunnel under reverse fault dislocation, this paper introduces the two-parameter Pasternak model and the vertical displacement profile equation. The analytical solution for the longitudinal mechanical response of the pipe or tunnel under reverse fault dislocation is obtained by solving the differential equation. The corresponding numerical simulations and model tests have been carried out, and the analytical solutions have been verified by combining the numerical simulation results and model test data. A parametric analysis is presented in which the effects of the shear stiffness of the elastic layer, the coefficient of subgrade reaction, the dip angle, and the ratio of soil thickness to tunnel diameter are investigated. The results show that as the shear stiffness of the elastic layer G increases, the difference between the bending moment and the shear force of the tunnel near the fault trace becomes smaller, and the value of the maximum displacement increases. As the coefficient of subgrade reaction k increases, the maximum deformation location of the tunnel is closer to the fault trace, the difference between the bending moment and the shear force of the tunnel is greater, and the active length decreases. The displacement, bending moment and shear force distributions of the tunnel become closer to the footwall as the dip angle alpha increases. The increases in the ratio of soil thickness to tunnel diameter H-2/D lead to the distance of the maximum displacement position from the fault trace, the difference between the bending moment and the shear force decreases, but the active length increases.