Detection of Old Mine Workings over a Part of Jharia Coal Field, India using Electrical Resistivity Tomography

ABSTRACT Old mine workings, mainly hidden galleries, goafs, shafts etc may pose a great threat to the local environment and also for future mine development. The present study mainly deals with delineation and mapping of old mine workings over Tikmani-Gareriya section, a part of east Basuria colliery, Jharia coal field, India using state-of-the-art 64 electrodes and 61 channel FlashRES-Universal electrical resistivity tomography (ERT). ERT data have been acquired along a line at 5m electrode spacing covering total profile length of 315m using Wenner, Schlumberger, Gradient and Dipole-Dipole arrays over a known old mine working. Further joint inversion of all combined arrays has also been carried out using 2.5D resistivity inversion program to combine the relative advantage of all arrays for producing superior results. The acquired data have been analysed using four different thresholds for all arrays with quality factors 15, 10, 5, and 1; each with 60mA current. 2D inverse resistivity models generated using Joint inversion of all combined arrays with quality factor 5 provides best result for delineation of coal pillars, galleries and goafs followed by Gradient, Schlumberger, Dipole-Dipole and Wenner arrays with same quality factor. Coal pillars have been identified with relatively high resistivity anomaly whereas galleries and goaf have been delineated with relatively low resistivity anomaly. The estimated range of resistivity variation of coal pillars have been well corroborated with published results. The results prove the efficacy of the ERT technique for detection of old mine workings.