Processes, Vol. 13, Pages 1743: Research on the Method of Determining the Loosening Circle and Sealing Depth of High-Gas Coal Bed Roadway Based on Direct Current Method

Processes doi: 10.3390/pr13061743

Authors:
Chunguang Wang
Qiang Liu
Liming Qiu
Hairui Liu
Zhenlei Li
Jintao Dang
Jun Wang

Gas extraction is the main method to reduce the gas content of a coal seam and prevent coal and gas outburst. The sealing depth is one of the key parameters affecting the sealing effect. The principle of the high-density direct current method is to lay electrodes underground, and by injecting a stable DC current into the underground medium, the potential difference is measured to calculate the apparent resistivity, which reflects the difference in electrical conductivity of the underground rock or coal body, and then inferring the physical characteristics, such as its structure, water content, or stress state. Based on the basic principle of the high-density direct current method, this study analyzed the change rule of resistivity after the secondary stress of the roadway; tested the distribution of the roadway stress field in Juji Mine; and finally, determined the sealing depth of this coal seam. The main conclusions were as follows: The resistivity of the loose crushing zone after the roadway disturbance stress corresponded to the plasticity and destruction stage of the coal body, and the resistivity was larger compared with that of the original rock stress area. The stress concentration zone corresponded to the compression stage, where the destruction of the coal and rock state was smaller, and the resistivity was smaller compared with that of the original rock stress area. The range of the loose circle of the roadway of the coal seam was 6 m, and the range of the stress concentration zone was 6–17.5 m. The range of resistivity changes of the loose crushing zone was larger, and it had a large range of resistance, which had a good effect. The resistivity of the loose broken zone varied widely and was random, while the visual resistivity of the stress concentration zone was basically the same and was stable.

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