2D Resistivity Imaging for Delineation of Waterlogged Coal Workings in Unapproachable Underground Coal Mines to Check Inundation Hazard

Abstract

2D Resistivity Imaging survey is a relatively a new technique used for detecting old, abandoned & unapproachable waterlogged areas in underground mines in recent years. Hingir Rampur Colliery of Mahanadi Coalfields Limited (MCL) was facing problem due to presence of unapproachable underground waterlogged coal workings. Mine management was extracting coal in Seam I of Hingir Rampur seam (HR Seam) at the depth of 100 m. As they had planned to progress the workings of Seam I towards waterlogged goaves of 9 & 11 pits, they proposed to explore the status of waterlogged workings between Seam I of Hingir Rampur colliery and waterlogged goaves of 9 & 11 pits so that they could leave at least 60 m coal barrier from the waterlogged area to check inundation hazard.

For this purpose, Resistivity Imaging (RI) survey were conducted along the six profiles A, B, C, D, E and F in Hingir Rampur colliery in the proposed area for exploration of the waterlogged workings between Seam I and waterlogged goaves of 9 & 11 pits. Pole-pole array of RI survey was used in this study. Considering the indirect approach of geophysical methods, two boreholes (CMRI-31 & CMRI-32) were being drilled along the profiles D and F to confirm the RI data, which were nearer to the coal extraction site. After correlating and corroborating of borehole data with RI data, it was confirmed that strata were hard, compact and dry at 60 m from the surface and continued up to 146 m depth. Hence, it was concluded that mining can be done safely at the depths varying from 100 m to 146 m.