Three-dimensional (3D) tunnel geological
advance prediction methods currently face several challenges: (1) The
arrangement of shot and geophone points is complex and nonlinear, preventing
the use of directional filtering techniques to extract reflected waves in the
advance direction, which results in a low signal-to-noise ratio (SNR); (2) the direct wave arrival is unsuitable for
estimating the surrounding rock velocity; and (3) geophones are positioned on
the tunnel walls, far from the tunnel face, leading to low illumination energy
for the target body in the forward direction, which decreases the accuracy of
anomaly imaging. To enable true 3D fine detection and imaging of unfavorable
geological bodies in the tunnel advance direction, the author proposes a 3D
seismic advance prediction method for tunnels with wide illumination and high
SNR. A 3D symmetric observation system (STSP) is designed, and its advantages
are evaluated through numerical simulation, illumination analysis, and 3D
reverse time migration method. Results from the analysis of irregular karst
cave and weak interlayer models highlight the following advantages of STSP: (1)
The shot points in 3D STSP are arranged linearly, which facilitates extracting
reflected waves in the advance direction via directional filtering, resulting
in high data SNR. (2) In terms of illumination energy and range of the target
layer, 3D STSP outperforms 3D true reflection tomography (TRT). (3) 3D STSP
provides high offset imaging accuracy, whereas TRT shows insufficient accuracy
in imaging the inclination and trend of geological bodies.
XIAO Yulan
. Three-Dimensional Seismic Advance
Prediction Method for Tunnels With Wide Illumination
and High Signal-to-Noise Ratio[J]. Tunnel Construction, 2025
, 45(4)
: 782
-794
.
DOI: 10.3973/j.issn.2096-4498.2025.04.012
