Abstract
With mining depths increasing, coal and gas outburst disasters are becoming more and more serious and complicated, which directly restricts the production efficiency of coal mines. In order to study the rules of energy dissipation during the occurrence of a coal and gas outburst based on the occurrence mechanisms, a simulation experiment of a coal and gas outburst with a ground stress of 16 MPa and a gas pressure of 0.5 MPa was carried out using a self‐developed large‐scale coal and gas outburst simulation experimental system. A quantitative analysis was given based on the energy model. The results showed the following: (1) In the process of the coal and gas outburst, the main energy source originated from the elastic potential energy of the coal body and the gas internal energy. The main energy loss was used for coal crushing and throwing. (2) The outburst coal sample in this experiment had a mass of 18.094 kg, and the relative outburst intensity was 1.21%. Additionally, the farthest throwing distance of the outburst coal samples was 3.3 m away from the outburst hole wall. The distribution of the outburst coal sample decreased along the roadway, and the proportion of the coal sample grain size in each area first decreased and then increased with the decrease of the grain size. The coal samples with a grain size less than 0.2 mm after the outburst accounted for 6.34% of the mass of the total coal samples. (3) The elastic potential energy of the coal body accounted for 0.34% of the total outburst energy, while the gas internal energy accounted for 99.66%. It was verified that gas internal energy was the key energy source for the coal and gas outburst, and this internal energy was two orders of magnitude more than the elastic potential energy, playing a leading role in the outburst process. After the outburst initiation, most of the energy was consumed in coal crushing, which was in the same order of magnitude as the gas internal energy. Moreover, the energy losses due to friction, vibration, and sound during the outburst process comprised no more than 10% of the total energy. The research results can provide certain guidance for clarifying the mechanism of a coal and gas outburst and the quantitative analysis of outburst energy.
Highlights
A coal and gas outburst is an extremely complex gas dynamic phenomenon during which a large amount of pulverized coal is suddenly ejected from a mining face into a roadway or stope in a very short time, accompanied by large amounts of gas, which can destroy underground equipment
Eoretical research on coal and gas outburst energy has been undertaken for a long time, and rich results have been achieved, but most of these results only provide qualitative and simplified models, lacking support for highly similar simulation experimental data or verification with practical outburst cases. ere is relatively little quantitative research on coal and outburst energy. erefore, it is of great significance to establish an accurate and practical energy condition model of a coal and gas outburst and conduct indepth quantitative research with experimental data obtained by large-scale coal and gas outburst simulation experiments in order to reveal the energy conversion mechanism in an outburst process under multifield coupling conditions and to quantify the occurrence conditions and criteria for a coal and gas outburst
A similar simulation experiment was carried out using a self-developed large-scale coal and gas outburst simulation experimental system, followed with a quantitative analysis of energy dissipation in the outburst process, realizing the main conclusions as follows: (1) In the process of the coal and gas outburst, the main energy source existed in the form of coal elastic potential energy and coal gas internal energy. e main energy loss existed in the form of coal crushing work and coal throwing work
Summary
A coal and gas outburst is an extremely complex gas dynamic phenomenon during which a large amount of pulverized coal is suddenly ejected from a mining face into a roadway or stope in a very short time, accompanied by large amounts of gas, which can destroy underground equipment. Xu and Jiang [15] studied the rules of energy dissipation in the process of a coal and gas outburst, and they found that a peak value of gas expansion energy was released at the initial releasing moment of the gas from the coal seam after it was damaged by ground stress. Erefore, it is of great significance to establish an accurate and practical energy condition model of a coal and gas outburst and conduct indepth quantitative research with experimental data obtained by large-scale coal and gas outburst simulation experiments in order to reveal the energy conversion mechanism in an outburst process under multifield coupling conditions and to quantify the occurrence conditions and criteria for a coal and gas outburst Eoretical research on coal and gas outburst energy has been undertaken for a long time, and rich results have been achieved, but most of these results only provide qualitative and simplified models, lacking support for highly similar simulation experimental data or verification with practical outburst cases. ere is relatively little quantitative research on coal and outburst energy. erefore, it is of great significance to establish an accurate and practical energy condition model of a coal and gas outburst and conduct indepth quantitative research with experimental data obtained by large-scale coal and gas outburst simulation experiments in order to reveal the energy conversion mechanism in an outburst process under multifield coupling conditions and to quantify the occurrence conditions and criteria for a coal and gas outburst
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