Identification of Coal and Gas Outburst-Hazardous Zones by Electric Potential Inversion During Mining Process in Deep Coal Seam

Experimental Test and Field Observations of an Electric Potential Monitoring Device for Dynamic Hazards during Mining Activities

“…According to the above analysis, the EP signals can be generated in the mining process of coal seam, and the response characteristics of EP signals are closely related to the stress state and damage evolution process of coal and rock mass. The EP signals have the response characteristics of the strength rising to a high value for coal and rock dynamic disaster hazards (i.e., mining stress anomaly or coal cannon phenomenon), which can reflect the loading and damaging state of specimen, and reveal the hazard degree of the coal and rock dynamic disasters [9,10]. Therefore, through monitoring the EP signals inside the coal seam during mining activities, it is possible to identify the abnormal response characteristics, monitor and forecast the coal and rock dynamic hazards, which are prevented and controlled by taking targeted measures.…”

“…On the other hand, the process of EP monitoring is simple, requiring only the construction of ordinary boreholes with a small workload and negligible impact on production, which is similar to "non-destructive monitoring". The EP monitoring system can push the electrodes to the specified borehole depth through the pushing device, which can test the EP signals of the same borehole with different borehole depths in real time and continuously at high frequency, and realize the location monitoring of the EP spatial distribution law [10].…”

“…However, coal mass is a material with significant inhomogeneity and anisotropy, which makes it difficult to accurately monitor the failure and its precursor information of the coal body using traditional mechanical methods [7,8]. Previous studies show that the deformation and rupture process of a coal body can generate significant electric potential (EP) signals, and the EP response is closely related to the damage evolution process and stress state of the coal body [9,10]. Studying the EP response characteristics of a coal body during damage and failure processes can indirectly monitor the damage evolution process of a coal body and identify the precursor information of instability and failure of coal and rock mass [11].…”

The Calculation of Inelastic Zone Width of Coal Pillar in Highwall Mining With Backfill

“…RMSE, SSE, and R2 of fitting curves in each relationship formula show that RMSE and SSE are less than 0.05 and 0.03, respectively, and the R2 is greater than 0.87. Therefore (Li et al, 2021d;Kong et al, 2021;Shen et al, 2021;Kong et al, 2022;Niu et al, 2022), it can be explained that the fitted relationship formula has a high degree of fit with the experimental data and has a basis for use. Therefore, substituting Eqs 39-41 into Eq.…”

“…The reason why such a problem occurs is believed to be caused by two aspects. The first aspect may be that the model established in this study is based on the physical and mechanical parameters and other relevant parameters of the Antaibao open-pit mine 11 # coal obtained after average calculation and relevant treatment, while the numerical simulation is calculated directly based on the original parameters, which leads to the result of the numerical calculation is larger than that of numerical simulation; another (He et al, 2022;Niu et al, 2022;Yang et al, 2022) aspect may be that the grid density limits the numerical simulation, making it impossible to calculate the inelastic zone with a width of less than 0.35 m (in the numerical simulation, the grid width at the coal pillar is 0.35 m). Moreover Wu et al, 2022), it also leads to the result of numerical calculation being larger than that of numerical simulation.…”