In situ measurement of water accumulation in overlying goaf of coal mine-a transient electromagnetic-based study

Abstract

Water accumulation detection in mining areas is the primary technical means for preventing mine water disasters. To study the distribution of water accumulation in the goafs of the Xingnong coal mine in Jixi, the present paper systematically analysed the water accumulation regularities in the goafs based on the applied and theoretical studies using transient electromagnetic (TEM) methods for the detection of goaf water accumulation characteristics. Because of the high sensitivity of transient electromagnets to low resistance and water, the water body distribution in the goafs is determined by the exhibition of low resistance by the water bodies. Furthermore, the water-bearing anomalies are located depending on the conductivity difference among media. The analysis of the in situ measurements for the Xingwang coal mine revealed four water-rich goaf anomalous zones within the detection area, of which one was located in the shallower part and three were located in the deeper part. The water-retention capacity of the fault zones was analysed, with more reliable degree of control attained by analysing a fault with a large throw. A broad area of highly distinct low-resistance anomalies appeared in the vicinity of the fault. The suspicious water-containing anomalies were verified through field drilling experiment, proving the reliability of TEM in detecting the water distribution in the coal mine goafs.