Advanced prediction method of borehole acoustic detection in tunnels based on azimuth orientation and synthetic aperture imaging

In response to the demand for fine-scale detection of potential water-bearing structures in underground engineering, this paper proposes an acoustic forward prediction method based on azimuthal detection and synthetic aperture imaging. By integrating directional receiving technology with signal coherence enhancement algorithms, this method overcomes the resolution limitations of traditional geophysical approaches in confined borehole environments, enabling precise localization and imaging of concealed geological targets. Results demonstrate that the proposed technique effectively quantifies the azimuth of targets relative to the borehole axis. Furthermore, the synthetic aperture imaging framework integrates sparse sensor array signals via virtual beamforming, significantly strengthening the energy of weak reflected signals and achieving sub-meter anomaly detection. The method exhibits high azimuthal resolution and strong anti-interference capability, demonstrating superior performance in the fine characterization of deep-seated rock fractures and small-scale discontinuities. Theoretical modeling and numerical simulations validate the feasibility and engineering applicability of the method. This study provides a novel technical approach for forward geological forecasting, offering critical support for the prevention of water inrush ahead of the tunnel face and the optimization of support design.