Full-Space Apparent Resistivity Rapid Imaging Based on Point-Source Attenuation Fields for Roof Water-Hazard Monitoring in Coal Mining

Mining disturbances can promote roof separation, fracture propagation, strata collapse, and water-conducting fracture-zone development, increasing roof water-hazard risk. Conventional apparent-resistivity pseudosection imaging is useful for rapid display; however, restricted electrode deployment limits effective coverage and representation of anomaly position and spatial continuity. Time-lapse resistivity inversion can characterize progressive fracture development, but representation of discontinuous anomalies caused by rupture, fracture connection, or collapse can be affected by inversion model constraints. To address these limitations, this study proposes a full-space apparent-resistivity rapid imaging method based on point-source attenuation fields. Each current electrode is regarded as a point current source, and potential attenuation with distance is used to construct attenuation curves, map responses to target-region grids, fuse multi-source estimates, and extract representative apparent-resistivity values. Numerical simulations and a scaled physical model experiment show that the method improves the spatial continuity of electrical anomaly responses and provides a more direct representation of abrupt electrical changes. Field application indicates that the method can identify mining-related electrical anomalies in roofs and anomalous ranges potentially associated with fracture development. The maximum vertical extent of the electrical anomaly was approximately 37 m, which was broadly consistent with the empirical estimate of approximately 40 m. The proposed approach provides an efficient geoelectrical monitoring tool for roof water-hazard identification and fracture-zone delineation in coal mining.