回采工作面煤自燃气体演化规律及危险区域划分

Spontaneous combustion gas evolution law and dangerous zone division of coal in stope face

  • 摘要: 气体信息特征是解读采空区煤自燃不同状态特性的关键参数,如何在复杂的环境中获取气体变化规律及掌握其内在关联是构建煤自燃防治技术体系的关键。提出了利用小波变换分析工作面不同区域CO和O2体积分数在不同时间尺度下的演化规律,得到其演化过程、周期性分布以及2种气体之间的相关性等,以评价不同区域对煤自燃的灵敏度和相关性。研究结果表明:工作面CO和O2体积分数的变化具有多时间尺度效应,且在不同的时间尺度下均体现了一定的周期性,其中,同一区域内2种气体在较高时间尺度下的主周期分布相近,在较小时间尺度下主周期有显著差异。CO和O2体积分数的小波系数震荡特征体现了气体原始体积分数的波动过程,第一主周期下小波系数拟合方程的初振幅和初相位差反映了不同区域与煤自燃的相关性,其中采空区气体信息对煤自燃的相关度最高,高抽巷的相关度最低;以采空区与煤自燃的相关度为基准,得到采空区、上隅角袋子墙内、上隅角袋子墙外和高抽巷与煤自燃的相对相关度分别为1、0.16、0.12和0.09。根据相关度结合煤自燃"三带"分布,提出了精准划分煤自燃危险区域的构想。

     

    Abstract: The characteristics of gas information are fundamental parameters for comprehending the various states of coal spontaneous combustion in the gob. Understanding the gas change law and its intrinsic correlation in a complex environment is crucial for establishing a coal spontaneous combustion prevention and control technological system. This study employs wavelet transform to analyze the multiscale evolution law of CO and O2 volume fractions in different areas of the working face. The aim is to investigate the evolution process, periodic distribution, and correlation between the two kinds of gases in different regions. This analysis evaluates the sensitivity and correlation of different areas to coal spontaneous combustion. The findings suggest that the CO and O2 volume fractions at the working face exhibit multiscale effects and demonstrate a certain periodicity at different time scales. The main period distribution of the two kinds of gases in the same area is similar at higher time scales, whereas a significant difference exists in the main period at smaller time scales. The oscillation characteristics of CO and O2 volume fraction wavelet coefficients reflect the fluctuation process of the original volume fraction of the gases. The initial amplitude and initial phase difference of the wavelet coefficient fitting equation under the first principal period reflect the correlation between different regions and coal spontaneous combustion. The gas information in the gob has the highest correlation with coal spontaneous combustion, while the high extraction roadway exhibits the lowest correlation.Based on the correlation between the goaf and spontaneous coal combustion as the benchmark, the relative correlations of spontaneous coal combustion in the goaf, inside the bag wall at the upper corner, outside the bag wall at the upper corner, and in the high drainage roadway were 1, 0.16, 0.12 and 0.09, respectively. Furthermore, based on the correlation degree and the distribution of the "three zones" of coal spontaneous combustion, the study proposes the concept of accurately dividing the risk area of coal spontaneous combustion.

     

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