Abstract
Studying the parameters of a coal and gas hole (CGOH), such as the hole shape, hole size and volume, coal quantity of CGOH, coal throw distance, calculated hole density, and gas pressure, is helpful in revealing the coal and gas outburst mechanism. In this study, we found that there were close mathematical relationships between these parameters. A nonlinear composite function relationship (CGOH parameter equation) was observed between the coal quantity, CGOH volume, and throw distance. The correctness of these relationships was verified using the Origin software. The stagnation point and inflection point of the parameter curve were obtained through the derivation of the parameter equation, and the transformation path from coal and gas outburst to coal and gas extrusion or dumping was clarified. At the same time, the equations of gas pressure, coal quantity, and throw distance are derived.
Highlights
Coal and gas outburst (CGO) is a very serious dynamic phenomenon [1,2,3]
Based on the comprehensive effect hypothesis, numerous scholars have carried out a series of CGO simulation experiments in the laboratory [4,5,6,7,8,9,10]
Yan et al [12] used different gases in CGO simulation tests, which proved that higher gas pressures and better adsorption/desorption capacities corresponded to higher outburst strength values
Summary
Coal and gas outburst (CGO) is a very serious dynamic phenomenon [1,2,3]. Many scholars have conducted research on coal and gas outbursts and unanimously agree with the hypothesis of the combined effect of coal and gas outbursts. Sobczyk [17] used different gases to carry out CGO simulation tests He reported that N2 required a higher gas pressure than CO2 to cause CGO, while the duration of CO2 outburst was longer under the same gas pressure conditions. Carried out a CGO simulation test with a self-designed device and reported that the CGO characteristics of soft coals were more pronounced than those of hard ones, the outburst strength was larger, and there was an obvious sorting phenomenon. Starting from the CGO accidents that occurred in Yunnan Province, Guizhou Province, and Sichuan Province (i.e., YGC) of China, the CGOH parameters were obtained, sorted, selected, and analysed. From 1991 to 2020, 1083 coal mine accidents occurred with 2905 deaths in LPS, as shown in Figure 2 and Table 2, of which 1749 deaths (60.2%) were caused by gas accidents.
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