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Coal Mine Inclined Shaft Advanced Detection Method and Physical Model Test Based on Shield Cutterhead Moving Array Electrodes

Using tunnel boring machine (TBM) to construct inclined shafts in coal mines has become the main way for large-scale coal mines to enter deep mining faces. However, some engineering disasters such as water in rush and rock burst will occur when TBM crosses the aquifer and weak broken rock strata. For the sake of efficient tunneling and advanced optimization of the safety plan and supporting measures, it is critically important to detect the anomalous geological conditions in front of the driving face during the service of TBM. Based on the bore-tunneling electrical ahead monitoring (BEAM) system, this paper proposes a coal mine inclined shaft advanced detection method based on shield cutterhead moving array electrodes. First, as the BEAM system cannot image owing to its low utilization rate on spatial distribution information, a diversified excitation and measurement mode with the cutters on the cutterhead as the exciting electrode and measuring electrode is proposed to provide a calculation condition for inversion imaging of the geological condition in front of the driving face. Then, in order to improve the speed of inversion imaging, a virtual grounding electrode equivalent model is proposed to replace the original guard electrode model. Finally, in order to verify the effectiveness of the method, the influence of the virtual grounding electrode on the inversion results at different positions is studied through a physical model test and a numerical inversion test. The results show that the method can better reflect the position of anomalous body.