A FEM-based numerical study of responses of underground openings subject to plane, cylindrical, compressive and tensile waves

A FEM-based numerical study is carried out to investigate the dynamic responses of underground openings in jointed rock masses. The heterogeneity and damage process of rocks are taken consideration in the numerical study. Effects of joint normal stiffness, joint spacing, joint orientation, amplitude of applied stress wave, cylindrical wave and tensile wave on the measured Peak Particle Velocity (PPV) around the tunnel are addressed. The simulation results show that the existence of joints has great influence on the stability of the underground tunnel. In addition, the cylindrical wave decays quickly due to both geometrical attenuation and joint reflection. The PPVs around the tunnel are highly dependent on the source location of the cylindrical wave and the wave amplitude. Furthermore, the large-amplitude tensile wave is difficult to transmit across the joints, because of the caused opening of joints. However, for the shallow buried tunnel, the reflected tensile waves from the ground surface may still lead to the instability of tunnel.