Research on the coupled hazardous zones of coal self-ignition and CH4 blast in goaf during upward mining

During upward mining in coal mines, the gas in the lower goaf can flow to the upper goaf along the through fractures between the coal seams, which affects the distribution of the flow field such as the oxygen concentration and the gas concentration in the upper goaf. This paper explores the changes in the distribution regularity of the self-ignition zone in the goaf and the region coupled with the gas explosion range by comparing it with single-seam mining, taking the upward mining of a coal mine in Shanxi Province as an example. In this study, PFC2D software is used to simulate the range and voidage ratio of the first through fissure between close coal seams during up-mining. Then the distribution laws which of self-ignition zones and CH4 explosion ranges in the goaf under the two types of mining methods were compared and analysed using Fluent. Finally, according to the degree of overlapping between the self-ignition zone and CH4 explosion range, the distribution law of the two hazardous coexistence zones in the goaf was analysed. The research results are important for rapid identification and prevention of the above disaster areas.