三维动静组合荷载含瓦斯煤破坏机理及其瞬变声电信号特征研究

During the pregnancy and occurrence of coal and gas outburst, the deep coal seam has usually suffered the state of high overburden pressure and high gas pressure before being subjected to dynamic loads such as blasting vibration and excavation disturbance. This reveals that the occurrence of outburst is a typical three-dimensional coupled static-dynamic loading issue with high stress, high gas pressure, high temperature and dynamic disturbance. The dynamic characteristics of coal and rock mass have been widely investigated in the engineering research, but there are few studies pay attention to the influence of static-dynamic load properties and gas parameters comprehensively in the field of coal and rock dynamic disaster prevention. This project intends to design and realizes the SHPB impact test on gas-bearing coal under the three-dimensional coupled static-dynamic load, by comprehensively considering the influence of tri-axial stress, gas pressure and dynamic loading rate. The dynamic constitutive model of gas-bearing coal damage will be developed and used to deduce the regular pattern of energy accumulation, coal damage, and energy dissipation. Then, the precursor characteristics of gas outburst will be obtained according to changes of transient acoustic emission and the electrical signal resulting from the destruction of gas-bearing coal, and the mechanism of impact of methane gas on transient acoustic emission and electrical signal characteristics will also be studied. Moreover, the influence of charging and discharging of gas and the change of molecular structure of coal before and after the application of load will be studied by means of infrared spectrum analysis, and the microscopic mechanism of the damage of coal will be revealed. The project will provide the theoretical basis and technical support for the research on the mechanism and the prediction of coal and rock dynamic disaster.

在煤与瓦斯突出孕育和发生过程中，深部煤岩体在承受爆破震动、开挖扰动等动荷载作用前，通常已处于高应力和高瓦斯共同作用状态，深部突出实际是“三高一扰动”条件下煤岩体的三维动静组合加载问题。煤岩体的动力学特性一直是工程研究的重点，但在动力灾害防治领域兼顾动静荷载属性和瓦斯参量影响的研究较少。本课题拟通过综合考虑三向应力、瓦斯压力和动态加载速率等致突相关因素的影响，设计并实现含瓦斯煤的三维动静组合荷载霍布金森压杆冲击试验，以获取组合荷载破坏本构模型，推演动静组合荷载下含瓦斯煤的能量蓄积、损伤破坏和能量耗散规律；根据含瓦斯煤破坏产生瞬变声电信号的变化来研究突出的前兆特征，探究瓦斯对煤体动力学特性和瞬变声电信号特征的影响机理；利用红外光谱分析手段研究充放瓦斯和施加动载前后煤体的分子结构变化，揭示突出煤体损伤破坏的微观机制。课题将为含瓦斯煤岩动力灾害机理和灾害预测研究提供理论基础和技术支撑。

在煤与瓦斯突出孕育和发生过程中，深部煤岩体在承受爆破震动、开挖扰动等动荷载作用前，通常已处于高静应力和高瓦斯共同作用状态，深部突出实际是“三高一扰动”条件下煤岩体的多维动静组合加载问题。本项目兼顾动静荷载属性和瓦斯参量的影响，采取理论分析、实验测试、数值模拟和现场验证相结合的方法开展含瓦斯煤岩动态破坏特性研究：通过设计改进的霍布金森压杆（SHPB）冲击和落锤冲击加载试验装置，对含瓦斯煤开展三维动静组合荷载动态冲击测试；获取含瓦斯煤受三向应力、瓦斯压力和动态加载速率共同作用下的动态应力-应变特征，分析轴压、围压、瓦斯压力和应变率对煤岩强度、变形模量、能量吸收等的影响，得出含瓦斯煤的能量蓄积、损伤破坏和能量耗散规律，揭示瓦斯对含瓦斯煤样动态破坏特征的影响作用；构建含瓦斯煤的动态破坏本构模型，形成一种含瓦斯煤动态破坏的数值模拟分析方法；分析冲击破碎后煤体的粒度分形特征，利用红外光谱分析手段研究充放瓦斯和施加动载前后煤体的分子结构变化，探究瓦斯对煤体力学特性的微观影响机制；在实验室和瓦斯原始赋存煤体现场采集了煤体动态破坏过程中产生的声电信号，分析煤体破坏附加效应信号强度大小、波动形式、持续时间和频谱特征的变化，证实瓦斯煤体动态破坏和声电信号特征的影响作用。项目研究获取了含瓦斯煤岩动态冲击破坏的基础参数和变化特征，为含瓦斯煤岩动力灾害机理和灾害预测研究提供理论基础和技术支撑。