煤岩冲击破裂过程中瞬变磁效应及红外光谱特征研究

At present, the mining depth of majority of coal mines in China is deeper than 600m. With the growing mining depth, the stress and gas pressure increase significantly, the geological conditions change abnormally, which results in more frequent occurrence of the coal and rock dynamic disasters such as rock burst and coal and gas outburst. Non-contact prediction methods such as the micro vibration, acoustic emission and electromagnetic radiation have always been the research highlights all the time, and many research results have been produced. But these disasters still cannot be predicted accurately, mainly because those monitoring indicators are easily disturbed. The above index prediction accuracy will be affected by multi-point source of vibration wave reflection or superposition, and all kinds of electromagnetic interference from numerous electrical equipments under coal mine. The piezomagnetic effect of material has been get a good application in many fields for a long time. Practice shows that the rock and coal can produce piezomagnetic effect, while using magnetic field changes to predict disasters shows less applications in the coal and rock dynamic disaster monitoring field. This topic aims to study the precursory characteristics of coal and rock dynamic disasters by using magnetic signal changes, meanwhile it studies the variation of chemical bond inside of coal molecules before and after impact failure through infrared spectrum analysis so as to explore the mechanism of the magnetic field changes. This paper will lay theoretical foundation for the researches on the mechanism of the coal and rock dynamic disasters and disaster prediction.

目前我国大部分矿井开采深度已经超过600米，高的开采深度使地应力、瓦斯压力显著增大、地质条件异常变化，从而使冲击地压、煤与瓦斯突出等煤岩动力灾害发生更为频繁。长期以来微震、声发射、电磁辐射等非接触式预测方法一直是研究的热点，产生了许多研究成果，但是灾害预测的准确率依然很低，其主要原因是监测指标容易受到干扰。井下多点震源产生振动波的反射和叠加、众多的机电设备产生的各种电磁干扰均会影响上述指标预测准确性。长期以来材料的压磁效应在许多领域得到较好的应用，实践证明岩石和煤能产生压磁效应，但是在煤岩动力灾害监测领域利用磁场变化预测灾害的应用较少。本课题利用磁场信号的变化来研究煤岩动力灾害的前兆特征，同时利用红外光谱分析手段研究煤在冲击破坏前后的分子内部化学键的变化，探究其磁场变化产生的机理。为煤岩动力灾害机理的研究和灾害预测奠定理论基础。

冲击地压、煤与瓦斯突出等煤岩动力灾害预测中微震、声发射、电磁辐射等非接触式预测方法展现出较好的应用前景，但存在指标容易受到井下机电等各种背景噪声干扰的问题，导致预测的准确率很低。材料的压磁效应在许多领域得到较好的应用，但利用磁场变化预测煤岩动力灾害的研究较少。课题开展煤岩冲击破裂过程中瞬变磁效应及红外光谱特征研究，针对煤岩动力学特性和煤岩动力灾害的前兆特征中瞬变信号特征，并利用红外光谱技术分析煤在冲击破坏前后的分子内部化学键的变化，对磁场变化信号产生机理进行了有效探索。研究成果包括：（1）通过单轴压缩、霍普金森杆（SHPB）冲击压缩、落锤冲击等力学特性测试实验，发现长径比和原生层理结构对煤岩冲击破裂强度具有重要的影响，从宏观上解释灾害发生机理；（2）采用子弹侵彻煤岩数值模拟分析HJC本构关键参数的敏感性，发现fc和ρ敏感性最大，其次是 T、B、N、Pc，提出了使用“静态损伤变量”方法定量描述瓦斯对煤体强度弱化作用，获得含瓦斯煤岩HJC本构模型参数取值范围；（3）通过灰色关联度分析了力学参数对瞬变磁信号产生的影响规律，发现瞬变磁信号包含脉冲信号成分，脉冲数与脉冲持续时间成正相关性，并提出了针对瞬变磁信号的分源去噪方法；（4）分析了1/3焦煤和气煤落锤冲击破坏红外光谱特征，发现煤岩在外力作用下发生破坏的过程中煤体分子间氢键吸收强度变化非常明显，确定煤冲击破坏过程中分子结构变化规律，提出煤破坏过程中的瞬变磁信号的微观产生机理。成果为煤岩动力灾害机理的研究和灾害预测奠定理论基础。