Abstract
The early warning models for coal and gas outburst have become increasingly more important and have gained more attention in the mining industry in an effort to further improve mine safety. In the warning process, however, the theoretical models do not always work in a timely manner largely due to the delayed capture of the real time parameters. Based on the evolving mechanism of gas outburst, the gas emission is considered a dominant factor in this work because its data is attainable in real time and clearly characterizes the entire outburst process. In order to characterize and distinguish the variation of the gas emission during an outburst and normal mining activity, a total of four statistical methods were employed to quantify the variation of gas emission: the moving average, the deviation ratio, the dispersion ratio, and the fluctuation ratio. Also, the Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE) are also included to demonstrate the accuracy of the deep learning model for predicting the variation of gas emission. Developed from these six indicators, the multi-factor fuzzy comprehensive evaluation model forms the outburst early warning system by calculating the combined index of the difference among the indicators. The accuracy of the early warning system is examined in the case study of the “3.25” gas outburst hazard in Shigang Coal Mine. The results show advantages of the comprehensive evaluation model established from the six characteristic indicators when predicting an outburst.
Highlights
In 2020, China’s coal consumption accounted for 56.8% of the domestic primary energy consumption (National Bureau of Statistics China, 2021)
By comparing and analyzing the time series of the gas emission quantity, it is found that the gas emission quantity changes abnormally on the eve of coal and gas outburst, which is consistent with the occurrence law of coal and gas outburst
According to the analysis of the coal and gas outburst evolution process, a coal and gas outburst early warning index based on the combination of statistical indicators of the gas emission and deep learning indicators is proposed, which includes the moving average, the deviation ratio, the dispersion ratio, the fluctuation ratio, Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE)
Summary
In 2020, China’s coal consumption accounted for 56.8% of the domestic primary energy consumption (National Bureau of Statistics China, 2021). The obtained loss values RSME and MAPE, combined with the moving average, the deviation, the dispersion and the volatility of gas emission time series can comprehensively reflect the abnormal changes of gas emission before the outburst accident. This indicates that abnormal changes in gas emission quantity before the outburst has led to a decrease in the accuracy of the model. Analysis of Early Warning Results of Each Indicator System The gas emission quantity data of Shigang Coal Mine during the normal production from 19 March to 20 March is used to calculate the statistical indicators, the deep learning indicators and the comprehensive indicators to conduct the early warning. By comparing and analyzing the time series of the gas emission quantity, it is found that the gas emission quantity changes abnormally on the eve of coal and gas outburst, which is consistent with the occurrence law of coal and gas outburst
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