Boundary Determination of Concealed Structure Region Based on Electromagnetic Tomography

To further explore the root cause of the high roof collapse phenomenon of the 1303 working face, the high-precision tunnel detection of the 1303 working face was carried out by electromagnetic wave fixed point method, and three sets of structural perspective anomaly zones were obtained. Finally, three sets of concealed structures existed in front of the 1303 working face, respectively, coal seam fracture zone or interlayer fault, the affected area of the FJ₁₇ fault extension and the FJ₂₅ fault extension affected area. Combined with the current advancing position of the working face, it is revealed that the root cause of large area roof caving in the roof of the working face between 92^# support and 123^# support is the reflection of FJ₁₇ fault extending into the working face.