Advanced Detection Technology of Ground-Borehole DC Resistivity Method

A ground-borehole direct current (DC) method which supplies DC power on the ground and receives potential difference in the borehole is presented, in order to achieve long-distance, high-precision advanced detection of hidden aquifers in front of coal mine tunneling roadways. The results of the model calculation show follows: (1) The apparent resistivity abnormal curve shows the abnormal characteristics of positive and negative alternations. The alternation order of high electrical resistivity and low electrical resistivity is opposite, the alternation order of positive and negative anomalies is determined by the relative position of the ground power supply point, survey line and abnormal target. (2) The distance between the ground power supply point and the abnormal body is negatively correlated with the abnormal response amplitude, and the abnormal body size is positively correlated with the abnormal width. (3) The anomaly center position, relative line orientation and anomaly body width can be interpreted according to the apparent resistivity curve, and a fast interpretation method is proposed. (4) A ground similarity simulation is tested to verify the theoretical response results and interpretation methods. The high and low electrical resistivity response characteristics are consistent with the theoretical results, and the abnormal target information determined by the fast interpretation method is basically consistent with the actual situation. Theoretical analysis and similarity test show that the ground-borehole DC method can effectively detect the electrical anomalies on the side of the borehole, it can realize "one hole and multi-use", and provide a new geophysical exploration method for long-distance and high-precision advanced fine exploration.