Study on Anomaly Characteristics of In-Advance DC Detection of Water-Accumulating Gob in Abandoned Mines

According to the principle and grading standards of DC electric in-advance detection, the paper analyzed the geophysical characteristics of gob in abandoned coal mines, summed up the verified characteristics of DC electric anomalies in advanced detection of goaf water. The results showed that water-accumulating gob of abandoned mines is commonly characterized by low resistivity, the anomaly bigger than 2 δ (δ is square deviation) is disastrous anomaly; although the old workings full of water in abandoned mines have low resistivity, the amplitude and anomalies is not the same, there are some differences, the workings not fully filled with water have relatively low resistivity; water-accumulating gob near roof and floor sometimes have abnormal response of low resistivity because of infiltration of fractures. There exists interpretation ambiguity for advanced electric detection.