Scattering of plane P1 waves and dynamic stress concentration by a lined tunnel in a fluid-saturated poroelastic half-space

The scattering of plane fast compressional waves (P1 waves) by a lined tunnel shallowly embedded in a poroelastic half-space is solved by indirect boundary integration equation method for a poroelastic half space. The displacement amplification on ground surface, dynamic stress concentration within the tunnel, and pore pressure fluctuation on the interface are investigated in the frequency domain, and are also compared with the results of the corresponding unlined cavity. Numerical results illustrate that the scattering of plane P1 waves around the tunnel strongly depends on the porosity of the surrounding medium, frequency and angle of the incident wave, tunnel depth. Significant amplification effect on the surface ground motion and the hoop stress in the tunnel is observed in the case of high-porosity surrounding-rock and undrained interface.