深部开采复杂条件下煤层氧化特性研究

The phenomenon of coal oxidation and spontaneous combustion often occurred under high pressure, high temperature, high pore pressure and high intensity disturbance in the process of deep coal mining. In addition, there are many prominent problems in deep mining at present, such as the inaccuracy of forecasting techniques on coal spontaneous combustion, the difficulties in early identification and the lag of theoretical research on coal spontaneous combustion in deepen coal mining and so on. The current study makes an attempt to explore the microstructure evolution, infiltration, adsorption characteristics and endothermic, exothermic in the process of coal oxidation under different temperature, different oxygen pressure and different mining condition, to reveal the properties of deep coal oxidation, and the law between the description of the internal fissures of coal body structure changes and adsorbed oxygen under the parameters of oxygen permeability characteristics. The coal oxidation and its gas derived law under high-pressure different temperature and conventional temperature are compared. Based on the influence caused by the variation of oxygen, temperature and stress on coal oxidation, the study establishes the model of coal-oxygen interaction under coupling conditions of coal oxidation reaction-temperature- stress. Drawing on this, the study makes a theoretical analysis on the oxidation characteristics of deep mining coal seam, thus lay the theoretical foundation for the effective prevention of coal spontaneous combustion and forecasting techniques in the multiple and complex coupling conditions.

针对深部开采过程中煤层赋存的高地应力、高温、高孔隙压力及高强度扰动作用下频繁引发的煤氧化自燃现象，但又基于目前早期判识困难、预测不准和深井煤自燃理论研究滞后等突出问题。开展一系列不同温度变化、不同氧气压力和不同采动条件下，煤体氧化过程中微观结构的变化、氧气渗透、吸氧特性和吸热放热规律等试验研究，揭示深部煤体氧化特性和以氧气渗透特征参量宏观描述采动煤体内部孔隙结构变化与吸氧渗透之间规律，对比变压变温与常规升温氧化条件下煤体氧化特性和氧化产物衍生规律的差异，并基于氧气、温度、应力的变化对煤氧化反应产生作用，及煤的氧化反应反作用于氧气、温度、应力改变的实验基础上，建立煤体氧化反应-温度-应力的耦合条件下煤-氧作用模型。在此基础上，理论分析深井开采煤层的氧化自燃特性，为有效防治在多重复杂条件耦合下煤自燃预测及防治技术奠定理论基础。

针对深部开采过程中煤层赋存的高地应力、高温、高孔隙压力及高强度扰动作用下频繁引发的煤氧化自燃现象，但又基于目前早期判识困难、预测不准和深井煤自燃理论研究滞后等突出问题。本项目开展一系列不同温度环境、不同赋存应力条件下，采动卸荷后煤体氧化过程与特性，及煤体氧化孔隙裂隙微观结构变化的研究，分析了深部煤体氧化特性和以氧气渗透特征参量宏观描述采动煤体内部孔隙结构变化与吸氧渗透之间规律。获得了不同温度环境、不同赋存应力条件下煤样氧化规律，指出煤体初期氧化难易程度与赋存应力、煤体强度之间存在着临界阀值，随着埋深的增大，地应力增高，采动后的煤层氧化难易程度不断升高；当地应力达到一定程度后，煤样随地应力的增高，采动后的煤层氧化难易程度又降低。建立了煤体氧化难易程度与煤层赋存应力环境和煤体强度之间的关系式，即：σO=kσst，当k=1.136时，煤层赋存的应力环境采动后最易于氧化；当k<1.136时，k值越小，煤层赋存的应力环境采动后越难于氧化，当k>1.136时，k值越大，表明煤层赋存的应力环境采动后越难于氧化。获得了施加不同初始应力煤样的煤氧复合作用均比原始煤样强烈，表明受载煤样采动后，其更易于与氧气发生氧化反应，更容易自燃发火；建立了煤氧化至自燃的历经时间T与环境温度、氧化放热、应力之间关系，揭示了煤氧化产热/产气造成煤体中的微孔发生坍塌而影响氧化现象。在此基础上，理论分析深井开采煤层的氧化自燃特性，为有效防治在多重复杂条件耦合下煤自燃预测及防治技术奠定理论基础。