A Comparison of Surface-to-Coal Mine Roadway TEM and Surface TEM Responses to Water-Enriched Bodies

Abstract

The surface transient electromagnetic method (TEM) is a geophysical technology normally used in detecting water-enriched zones. However, with an increase of mining depth, the accuracy and reliability of surface detection is gradually reduced, and surface TEM cannot meet the requirements of highprecision detection for coal mine production safety. In this study, surface-to-coal mine roadway TEM is proposed to detect water-enriched zones in coal mines. The resolution of this method in detecting targets, however, is still unknown. Based on a 1-D layered model, the surface-to-coal mine roadway TEM response is numerically simulated using the finite-difference time-domain method (FDTD). The results show that the surface-to-coal mine roadway TEM has higher resolution of the target above the underground receiving point and weaker resolution of the target below the receiving point. 3-D geo-electric models for typical waterenriched zones such as a water-filled mining goaf, a water-filled fault and a water-filled collapse column are established. The surface-to-coal mine roadway TEM responses are numerically simulated and compared with the surface TEM responses. The results show that for the goaf model, the surface-to-coal mine roadway TEM response is more sensitive than the surface TEM response. For fault and collapse column models, the surface-to-coal mine roadway response is more sensitive than surface response in the early delay stage but less sensitive in the late delay stage. The present study provides theoretical support for device selection and for data processing interpretation in actual work.INDEX TERMS Transient electromagnetic method, borehole, surface-to-coal mine roadway, water-enriched zones, numerical modeling.

Application of Computer Simulation Method in Deep Underground Engineering of Complicated Geological Condition

“…Wu [15] used the FDS numerical simulation method to study the changes in mine tunnels at different temperatures, and their research was highly consistent with the measured results. Chang [16] combined the FDTD numerical simulation method with the TEM method to detect the water-rich regions around a mine roadway. The main problem that directly affects engineering safety is the large displacement of the roadway and the difficulty of supporting it.…”

Fine Detection and Analysis of Hidden Karst in Wellsite with Quasi-Three-Dimensional TDEM Based on Lateral Constraint

“…At present, a large number of scholars have made detailed discussions and studies on the formation mechanism of karst geological bodies [3,4], but how to accurately identify karst caves, underground rivers, cracks, and other hidden karst geological bodies is still a hot issue. Geophysical exploration is an economical, rapid, nondestructive, and efficient means, among which high-density electrical method, geological radar method, audio magnetotelluric method, time domain electromagnetic method, and surface nuclear magnetic resonance method are widely used in the detection of adverse geological bodies (karst caves, underground rivers, cracks, underground goaf, faults, and geological disaster investigation) [5][6][7][8][9][10][11]. With the digitization and intellectualization of instruments and the development of processing and interpretation technology, the scope of geological problems that can be solved is constantly expanding [12][13][14][15].…”

“…For solving the minimum value of the objective function in the lateral constraint quasi-three-dimensional inversion, the Gaussian-Newton method is used to solve equation (5).…”

A surface-tunnel frequency domain electromagnetic method for mineral exploration in Tajikistan area

“…For instance, this approach has been utilized with the SOTEM system (Su et al, 2010;Xue et al, 2013;Xue et al, 2021;Xue et al, 2022;Chen et al, 2015), they move both the transmitter and receiver to the underground tunnel and successfully improve the signal produced by the water-bearing fault. Chang et al (2019) get the Surface-to-Coal Mine Roadway TEM Responses to Water-Enriched Bodies. While, in this paper, we propose a new EM observation system called the Surface-Tunnel Frequency Domain Electromagnetic (FDEM) method, aimed at enhancing the EM signal from deeper mineral targets.…”