Fast interpretation using three-dimensional audio-frequency magnetotelluric (AMT) in goaf of hydraulic permeable coal mine

Coal mine goaf or stoping stage often face the hydraulic ponetration threat, how to predict it quickly, effectively and at low-cost becomes a difficult problem.An audio-frequency magnetotelluric (AMT) three-dimensional inversion and rapid interpretation scheme for hydraulic permeable goaf was presented and systematically discussed.The theoretical geo-electrical models were designed and the feasibility of the three-dimensional inversion of the goaf resistivity was fully discussed.The inversion interpretation results using the actually measured data have demonstrated that there is an obvious low resistive distribution in the goaf area.In some working faces, there are water-rich and low-resistance areas caused by roof fissure water conduction, and local caving zone is obviously connected with overlying aquifer.It provides a reference for the location of suspicious seepage, the monitoring of water level and inflow, and the formulation of subsequent mining planning.From the theoretical and empirical perspective, this study provides a new idea for the application of AMT method in the analysis and dynamic monitoring of the water rich state of the goaf, and the related methods can effectively improve the interpretation effect of hydraulic permeable goaf.