受约束动载破坏含瓦斯煤的电磁信号蠕变特征

Electromagnetic radiation technology is an important method for predicting coal and gas outburst. Acquiring accurate electromagnetic data is of importance to improve the prediction accuracy. Previous studies show that the electromagnetic characteristics are largely related to the deformation and rupture process of coal, and the confining pressure, the existence of gas and the loading rate also have impacts on coal and rock fracture characteristics. Due to the erosion effect of gas, coal become "soften" and brittle weaken. The electromagnetic signals in the impact damage process become more "peaceful". The electromagnetic signal appears creep phenomenon. Considering the coal and gas outburst characteristics, this project will apply damage to containing gas and confining pressure coalby Hopkinson pressure bar, and capture transient electromagnetic signals by ZDKT-1 transient magnetic field test system. The creep characteristics of electromagnetic signals will be simulated for the condition of disaster strikes, and explore its influencing factors. The shock compression constitutive model of containing gas and confining pressure coal will also be established. Numerical simulation will be used to analyze the instantaneous fracture instability characteristic of containing gas coal. The relationship between changes in the molecular structure of coal and injury severity and energy by infrared spectroscopy will be studied, and the microscopic mechanisms of the creep characteristics of electromagnetic signals will be analyzed. This study is helpful to improve the electromagnetic signals disaster prediction mechanism and its basic data. Moreover, it can provide evidence for estimating damage energy by the changes of molecular structure of coal.

电磁辐射技术是煤与瓦斯突出的重要预测方法，掌握准确的灾害电磁信号特征是预测的关键。研究表明，电磁特征与煤岩变形破裂过程密切相关，围压、瓦斯和加载速率均对煤岩破裂特性有较大影响。瓦斯对煤体的蚀损效应使煤体“变软”、脆性降低，导致其冲击破裂电磁信号变得比较“平和”，即出现电磁信号“蠕变现象”。结合灾害特征，本项目利用霍普金森冲击压杆对受约束含瓦斯煤进行冲击破坏，同时利用瞬变磁振系统捕捉该过程的电磁信号，模拟研究灾害发生时煤体瞬间破裂失稳的特性及破裂电磁信号的“蠕变特征”，探究其影响因素。建立受约束含瓦斯煤动载破坏的本构模型，数值模拟辅助分析含瓦斯煤瞬间破裂失稳特性。利用红外光谱技术，定量研究瓦斯对煤体分子结构、破裂失稳特性及破裂电磁信号“蠕变特征”的影响，并建立分子结构变化与损伤程度及能量的关系。本研究有利于完善突出灾害的电磁信号预测机理，也能为利用煤分子结构变化反演损伤能量提供依据。

电磁辐射技术是煤与瓦斯突出的重要预测方法，掌握准确的灾害电磁信号特征是预测的关键。研究表明，电磁特征与煤岩变形破裂过程密切相关，围压、瓦斯和加载速率均对煤岩破裂特性有较大影响。瓦斯对煤体的蚀损效应使煤体“变软”、脆性降低，导致其冲击破裂电磁信号变得比较“平和”，即出现电磁信号“蠕变现象”。课题开展受约束含瓦斯煤冲击破坏及电磁信号特征相关研究，研究成果包括：（1）建立含瓦斯煤动载破坏的本构模型，研究了被动围压、瓦斯和冲击速度对煤岩动态破碎特征的影响特征，分析受约束含瓦斯煤冲击破坏的动态过程及试件应力分布变化，研究了冲击速度、瓦斯对煤岩动态力学性质及破坏过程的影响；（2）利用分形理论，研究了煤动载破坏后粉煤粒度分布特征的影响，建立粒度分布特征与冲击能量、电磁信号特征等关系，探寻粉煤粒度分形、电磁信号特征反演损伤能量、破坏程度的规律；（3）现场了测试受约束含瓦斯煤在冲击破裂过程中的电磁信号特征，并进一步该过程中出现的电磁辐射及微震信号特征间的相关性；（4）提出了一种基于总体经验模态分解和频域约束独立成分分析的去噪方法，该方法可有效处理现场电磁信号模态混叠问题。（5）建立了适宜评价煤岩冲击脆性的指标，可描述煤岩材料在冲击载荷作用下的脆性特征。研究成果有利于完善煤与瓦斯突出灾害的电磁信号预测机理。