School of Civil Engineering, Xuzhou University of Technology, Xuzhou, 221018, People's Republic of China.
School of Safety Engineering, China University of Mining and Technology, Xuzhou, 221116, People's Republic of China.
Environ Sci Pollut Res Int. 2023 Jan;30(2):4733-4743. doi: 10.1007/s11356-022-22528-5. Epub 2022 Aug 16.
The accurate division of three zones of coal spontaneous combustion in the goaf plays a vital role for coal fire prevention. Based on the O and CO volume fraction acquired from in situ test, this paper first fits the linear equation (characteristic equation) of O volume fraction with the length of the goaf. Then a cloud map of the kernel density distribution of O and CO volume fraction and the length of the goaf was drawn. According to the cloud map of CO, the distribution interval of CO volume fraction can be obtained, in which 0-100 ppm is the acceptable range, and greater than 100 ppm is the dangerous range, which can be used as a critical indicator for early warning of coal spontaneous combustion. According to the kernel density distribution cloud map of O volume fraction, there are 3 peaks of the kernel density of O volume fraction. According to the difference test, the 3 goaf lengths (characteristic lengths) corresponding to the 3 kernel density peaks are determined to be 12 m, 34 m, and 59 m, respectively. The characteristic O volume fractions are obtained by substituting characteristic lengths into the characteristic equation, which are 17.9%, 13.6%, and 8.9%. Different from the traditional dividing method, the characteristic O volume fractions and characteristic lengths divide the goaf into four areas: the heat dissipation zone, the first oxidation zone, the second oxidation zone, and the asphyxiation zone. The results of this study could refine the division of coal spontaneous combustion dangerous areas, reflect the dynamic change process of coal spontaneous combustion dangerous areas, and improve the efficiency of coal spontaneous combustion prevention.
准确划分采空区煤自燃的三个区域对预防煤炭自燃起着至关重要的作用。本文基于现场测试获取的 O 和 CO 体积分数，首先拟合 O 体积分数与采空区长度的线性方程（特征方程）。然后绘制了 O 和 CO 体积分数及采空区长度的核密度分布云图。根据 CO 的云图，可以得到 CO 体积分数的分布区间，其中 0-100ppm 为可接受范围，大于 100ppm 为危险范围，可作为煤炭自燃早期预警的临界指标。根据 O 体积分数的核密度分布云图，存在 3 个 O 体积分数的核密度峰值。根据差异检验，确定了对应于 3 个核密度峰值的 3 个采空区长度（特征长度）分别为 12m、34m 和 59m。通过将特征长度代入特征方程，得到特征 O 体积分数分别为 17.9%、13.6%和 8.9%。与传统划分方法不同，特征 O 体积分数和特征长度将采空区划分为散热区、初次氧化区、二次氧化区和窒息区四个区域。本研究结果可以细化煤炭自燃危险区域的划分，反映煤炭自燃危险区域的动态变化过程，提高煤炭自燃防治效率。
