采空区隐蔽火源位置的精准探测一直是煤火灾害防治的重大难题之一，也是保证灭火效果的关键所在。作为一种行之有效的火源探测技术，同位素测氡法已在多个自然发火严重矿区得到了应用。采空区氡气主要来源于煤自燃及其高温影响范围内岩体的氡气析出，因此深入研究自燃过程中煤岩介质体氡析出特性将对完善探测理论，提高采空区隐蔽火源精准定位具有重要意义。本文在分析煤岩体氡析出机理的基础上，对氧化升温过程中长焰煤及4种常见沉积岩石的氡析出规律进行了研究。结果表明，相同温度下，煤体氡气析出量随时间延长呈对数形式增加。随着温度上升，煤中氡气析出与温度之间呈现出良好的正相关关系，温度越高，氡析出量越大。受自身岩性差异影响，4种沉积岩石在整个升温过程中表现出了不同的氡析出特性。灰岩和砂岩在整个升温过程中氡析出量较小，而页岩和泥岩的氡析出量较大。根据煤岩介质体氡析出变化的特征温度，可将采空区氡气源形成划分为3个阶段：Ⅰ阶段(30~100 ℃)，受水分蒸发影响，氡气主要与煤体、页岩及泥岩等含水量较大的煤岩体氡析出有关;Ⅱ阶段(100~200 ℃)，氡气源主要来源于煤体和泥岩内部氡气的运移;Ⅲ阶段(200~300 ℃)，煤体发生热解，内部封闭孔隙空间内氡气析出是采空区氡气的主要来源。

Accurate detection of hidden fire source location in goaf has always been one of the major problems in coal fire disaster prevention and control.Surface-based radon detection technology has been successfully applied in multiple fire zones as an effective technique for detecting underground heat sources.Radon source in goaf mainly derived from coal spontaneous combustion and radon exhalation on the rock surface with the high-temperature influence.Therefore,the research on the radon exhalation characteristics of coal and rock during spontaneous combustion will be of great significance to improve the theory and the precise location of hidden fire source in goaf.Based on the analysis of radon exhalation mechanism of coal and rock,the radon activity concentrations of long-flame coal and four common sedimentary rocks during oxidation and heating are studied.The results show that at the same temperature,the radon activity concentration increases logarithmically with time.As the temperature increases,there is a good positive correlation between radon exhalation and temperature.The higher the temperature,the greater the radon exhalation.Affected by the nature of the rock,the four types of sedimentary rocks exhibit different radon exhalation characteristics during the whole process.The radon activity concentration in limestone and sandstone is relatively small,while the radon activity concentration in shale and mudstone is large.The formation of radon source in goaf can be divided into three stages according to the radon exhalation characteristics at different temperatures.In the first stage (30-100 ℃),affected by water evaporation,radon source is mainly related to the radon exhalation from coal,shale and mudstone with large moisture content.In the second stage (100-200 ℃),radon source mainly comes from the radon migration in coal and mudstone.In the third stage (200-300 ℃),the coal undergoes pyrolysis,radon exhalation from the internal closed space is the main source of radon gas in goaf.

1 煤岩介质体氡析出机理

2 煤岩体氧化升温实验

   2.1 实验装置

   2.2 实验方案

3 煤岩体氧化升温过程中氡的析出

4 关于煤岩体氡析出量的讨论

5 结论