Detection of Top Coal by Conductively-Guided Borehole Radar Waves: Results from Numerical Modelling

摘要: Damage to the tops of coal seams caused by incorrect blast stand-off distances is a serious issue in Australian industry, costing equivalent about one open cut mine for every 10 operating mines lost coal. To date, no effective and economically-sound techniques have been found map characterize seam structures environment. We propose use conductively-guided borehole radar (BHR) waves real-time prediction during blast-hole drilling. The method uses conventional with dipole antenna, which can image sideways around borehole, electrically coupled conductive wire or steel drill-rod induce guided wave along axial drill-rod. ahead BHR becomes part radiating antenna. travels end drill-bit where some its energy reflected back, while remainder radiates from drill bit. radiated will be geological discontinuities such as top seam, recorded BHR. In this paper, numerical modeling used investigate feasibility affecting factors guided-BHR-wave-based approach predicting It demonstrated that conductivity overburden most important factor our ability see bit; could prediction; theoretical error less than cm forward-looking capability 4-6m achieved based on modelling results.