Numerical simulation of the time-domain seismic wave evolution characteristics for advanced geological detection in tunnels

The identification of adverse geological bodies in front of the tunnel excavation face is essential to allow precautionary measures to be taken for safer tunnel construction. Currently, the interpretation of seismic data in tunnels relies more on experience, which is the result of a lack of understanding of the seismic wave propagation mechanism in tunnels. Therefore, on the basis of the finite element method of seismic waves in two-phase media, we investigated the time-domain evolution characteristics of seismic waves in tunnel spaces with two typical adverse geological bodies, namely, water-bearing fracture zones and lithological interfaces. The results show that under the combined influence of solid–solid and solid–fluid phase reflections, the propagation complexity of the seismic wave significantly increases, and the obvious diffraction phenomenon caused by the tunnel face plays a promoting role. The amplitude attenuation of the waves obtained from the self-defined factor is exponentially related to the propagation time, which is influenced by the energy difference of the wave itself and the degree of wave cross talk in the propagation process. This study can provide theoretical guidance for the technological development and field application of tunnel geological detection.