Monitoring Direct Current Resistivity During Coal Mining Process for Underground Water Detection: An Experimental Case Study

Karst water may break into coal tunnels through the rock fissures and cause severe coal mine disasters. The direct current resistivity (DCR) is sensitive to underground water and can be used to detect fissures during the coal mining process. However, the three-dimensional (3-D) measurement of the DCR is still a challenging task and has not been applied to the practical coal mining dynamic process. To bridge this research gap, this study proposes a new 3-D cross-borehole method by monitoring the DCR at multiple points to analyze the geoelectrical field evolution in the underground coal mining process. Based on the forward and inversion theoretical analysis, a DCR observation system is developed for a real unground coal mine to evaluate the cross-borehole points. The 3-D resistivity distributions at different positions in the coal mining process are calculated. The analysis result demonstrates obvious resistivity changes with the evolution of the Karst water zone during the coal mining, and the location and movement of the Karst water can be well estimated. As a result, the proposed 3-D cross-borehole method is very effective for monitoring the DCR and is able to accurately detect the underground water.