Research On Blind Ore Body Detection Around Holes With Hole And Cross-hole Gradient IP Method

As an important part of in-hole electrical exploration, hole and cross-hole gradient IP methodshave got wide use in resource prospecting and engineering geological investigation etc. withgood results. Based on3D finite element numerical simulation of IP method, we applied holeand cross-hole gradient IP simulation to theoretical models and analyzed the law of anomalies,which has guiding significance for blind ore body detection to some extent.We introduced the theory and field work of hole and cross-hole gradient IP methods, builtthe geo-electrical models according to measured data, calculated the apparent resistivity andapparent polarizability of different models with3D finite element numerical simulationprogram and equivalent resistivity method, plotted the hole and in-hole geo-electrical sectionsand analyzed the relationship between anomaly and blind ore body. Conclusions can be drawnfrom analysis of the anomaly law of different models with hole and cross-hole gradient IPmethods. Firstly, apparent polarizability has a better reflection of anomaly than apparentresistivity does. Unlike the apparent resistivity, Surface topography and tunnel almost have noinfluence on apparent polarizability. Thus, we can take apparent polarizability as the mainparameter in hole and cross-hole gradient IP methods and apparent resistivity as thesubordinate one. Secondly, the smaller the distance from the measured hole to the anomaly is,the lager the anomaly amplitude is and the better the detection effect is. Besides, the smallerthe distance from the power supply hole to the anomaly is, the lager the anomaly amplitude is.From the apparent resistivity and apparent polarizability analysis of different holes, we cantell the position of anomaly relative to holes and its extension direction.From data processing and results analysis of cross-hole gradient IP method at a mine inGansu province, we can see that the hole and cross-hole gradient IP methods do have effect inblind ore body detection around holes and can provide reference for blind ore body detectionin tunnels.