Effects of Roadway Undulations on Response Characteristics of Mine DC Resistivity and Their Correction

Undulations in mine roadway roofs and floors distort the current field of the mine DC method and displace sounding point positions, thereby distorting the apparent-resistivity pseudosections and degrading the accuracy of geological interpretation. To address this problem, we establish V-shaped and inverted-V-shaped undulating roadway geoelectric models using the finite-element method based on full-space DC electric-field theory. We perform forward simulations in homogeneous and layered media to investigate how roadway cavities and undulations affect detection results and response characteristics. We then apply a combined correction approach using orthogonal projection and a ratio method. The numerical simulations indicate that a funnel-shaped spurious high-resistivity anomaly appears beneath the trough of the V-shaped roadway, and a vertical, column-shaped spurious low-resistivity anomaly appears beneath the crest of the inverted-V-shaped roadway. After combined correction of the undulating-roadway models with inclinations of 5° and 15°, these spurious anomalies are markedly weakened, and the spatial positions and electrical characteristics of the anomalous-body responses agree more closely with the values prescribed in the geoelectric models. Application of the method to the return airway of panel 23501 at Shaanxi Shanmei Chenghe Mining Co., Ltd. Dongjiahe Coal Mine Branch (Dongjiahe Coal Mine) shows that the low-resistivity anomaly near 630 m is significantly weakened after combined correction. Analysis of the roadway-floor elevation, borehole water-inflow, and grouting data suggests that roadway undulation may be one of the important factors responsible for this low-resistivity anomaly. This method provides a feasible approach for correcting mine DC resistivity data acquired under undulating roadway conditions.