Division of spontaneous combustion risk zones in coal mine gob areas using gas kernel density distribution

doi:10.16265/j.cnki.issn1003-3033.2025.12.1445

Abstract

Abstract:

To prevent coal spontaneous combustion disasters in the gob area and precisely delineate hazardous zones, the variation patterns of CO and O₂ volume fractions along the gob length were statistically analyzed based on field measurements. Critical warning threshold ranges for spontaneous combustion were established and a gob hazard zoning method based on gas volume fraction kernel density was proposed. The results demonstrate that O₂ volume fraction exhibits a linear variation with distinct stages, and the variation rate before the inflection point is lower than that after the point. The CO volume fraction follows a quadratic polynomial variation. The kernel densities of both CO and O₂ volume fractions decrease with increasing gob length. Their highest kernel density distributions occur within 0-10m and 0-30m, respectively. O₂ volume fraction is more stable before the inflection point but exhibits greater fluctuation afterward. The average upper and lower acceptable limits for O₂ volume fraction before and after the inflection point are 3.3% and 6.3%, respectively. The critical CO and O₂ volume fraction values for hazard zoning based on kernel density are 0.009% and 15.1%, which divides the gob area into four quadrants and three risk levels (safe, potentially hazardous, and hazardous).

Key words: coal spontaneous combustion, gob hazardous zone, coal fire early warning, kernel density, statistical characteristics

CLC Number:

X936

GUO Qing, REN Wanxing, WANG Shengcheng, WANG Hao. Division of spontaneous combustion risk zones in coal mine gob areas using gas kernel density distribution[J]. China Safety Science Journal, 2025, 35(12): 96-102.

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支架	变化方程	可接受区间/%
30号	y=18.96-0.111 5x,x<30	$L{\|}_{{l}_{1}}^{{l}_{2}}$=3.1
30号	y=23.65-0.245 1x,x>30	$L{\|}_{l{\text{'}}_{1}}^{l{\text{'}}_{2}}$=5.6
45号	y=19.18-0.151 8x,x<30	$L{\|}_{{l}_{1}}^{{l}_{2}}$=5.8
45号	y=20.73-0.195 4x,x>30	$L{\|}_{l{\text{'}}_{1}}^{l{\text{'}}_{2}}$=6.4
60号	y=18.91-0.116 5x,x<30	$L{\|}_{{l}_{1}}^{{l}_{2}}$=3.5
60号	y=20.27-0.178 8x,x>30	$L{\|}_{l{\text{'}}_{1}}^{l{\text{'}}_{2}}$=6.9
75号	y=18.96-0.138 7x,x<30	$L{\|}_{{l}_{1}}^{{l}_{2}}$=3.1
75号	y=16.81-0.106 1x,x>30	$L{\|}_{l{\text{'}}_{1}}^{l{\text{'}}_{2}}$=6.1

支架编号	O₂体积分数指标对应分界点/m
支架编号	15%	5%
30	35.5	76.1
45	27.5	80.5
60	33.6	85.4
75	28.6	111.3