Water-bearing geological structure is a serious threat to coalmine safety. This research focuses on detecting water-bearing geological structure by transient electromagnetic method. First, we introduce the principle of mining transient electromagnetic method, and then explain the technique of Finite Different Time Domain using in the transient electromagnetic method. Based on Maxwell equations, we derive the difference equations of electromagnetic field and study the responses of water-bearing geological structure using FDTD. Moreover, we establish the relationship between receiving electromagnetic field and geological information. The typical coal geological model of goaf-water is chosen to do the numerical simulation. Besides, we verify the availability of the method by numerical simulation using coal geological model. Finally, we use the method in the coalmine which is located in Linfen city in Shanxi province in China, and the detecting result is verified by drilling.

Although many geophysical techniques have been used to detect the disaster geological anomalous body in the Huaibei coal mine company, there are still many mining disasters happening. The main reason is that the coal seam is rich of water in Huaibei coal areas. If the ground water connects with tunnels, it will cause the flood to collapse the coal seam. However, these dangerous geological bodies usually are very hided from the viewpoint of traditional electromagnetic and seismic methods. Due to the great difference of permittivity between the water-bearing rock and the surrounding rock, the high frequency electromagnetic wave can be received by a Ground Penetrating Radar (GPR) to detect the water-bearing rocks. Hence, we try to employ the high frequency electromagnetic wave to detect the water-bearing rock, which frequently results in a coal mining disaster. Firstly, the numerical simulations based on the theory research and its` effectivity analysis are done. Then, the method is used for the coal mine of Huaibei Company. Finally, the comparison between the detected results and the geological drilling information indicates the detection effectiveness of the GPR (Ground Penetrating Radar) in the coal mine tunnel.

Based on the characteristics of mine goafs, the geo-electrical models are established. In order to study the response characteristics of goaf by transient electromagnetic method, we have performed three-dimensional numerical simulations in three cases, geo-electrical model of mine geology without goaf, geo-electrical model of mine geology with low resistivity goaf and geo-electrical model of mine geology with high resistivity goaf. Moreover, the physical experiments have also been performed for the above three cases. Furthermore, we compare numeral simulation results and physical experiment results. Finally, we obtain the conclusion that although the response of high resistivity goafs is weaker than that of low resistivity, its response characters still can indicate the existing of goaf. Hence, above work actually signifies that shallow high resistivity goafs can be detected in a reliable way by transient electromagnetic method.