深部高瓦斯冲击危险煤层灾变演化规律研究

The dynamic disasters which occur in coal seam with high gas and bursting danger in deep coal mine have the characteristics of complexity and diversity. The control of gas pressure on bursting potential is the main reason for the transformation of dynamic disasters. The project takes special briquette with different bursting potential ranks as the experimental object, applying self-manufactured solid-gas coupling experimental device to test mechanical properties and bursting potential indexes under gas pressure constancy and sudden drawdown before and after gas drainage. The intensity recovery rate represents the influence of gas pressure changing on the mechanical properties quantitatively. It evaluates the sensitivity of the bursting potential index to the changing of gas pressure by the sensitivity identification model. It also determines the gas pressure threshold for the transformation between bursting potential ranks. A damage and degradation model representing bursting potential of coal samples is established under gas pressure. The mining effect is simulated by controlling the triaxial loading path and it is established that mathematical model for gas pressure-strain-gas permeability based on different mining stress condition. Based on the gas pressure and the different mining stress condition, the instability type and its transformation mechanism is revealed. And the critical threshold of gas pressure (content) is determined, establishing the intrinsic connection between gas pressure (content) and the risk of dynamic disaster. The research results provide a scientific basis for the prediction and prevention of dynamic disaster before and after gas drainage in deep coal seam with high gas and bursting potential.

深部高瓦斯冲击危险煤层动力灾害的发生形式具有复杂性和多样性。瓦斯压力对煤样冲击性能的控制是动力灾害形式发生转化的主要原因。项目以研制的具有不同冲击危险等级的型煤为实验对象，采用自制的煤岩固-气耦合实验装置，在抽采前后瓦斯压力恒定与骤降两种工况下实测煤样强度参数与冲击倾向性指标，利用强度恢复率定量表征瓦斯压力对煤样力学性能的影响作用；采用敏感度识别模型评价冲击倾向性指标对瓦斯压力变化的敏感性；确定冲击倾向性等级跃迁的瓦斯压力阈值；建立瓦斯压力作用下煤样冲击性能损伤劣化模型；利用控制三轴加载路径的方式模拟采动效应，建立不同采动应力状态下瓦斯压力-应变-瓦斯渗透率的数学模型，基于瓦斯压力与不同采动应力状态揭示煤样失稳形式及其转化机理，确定瓦斯压力（含量）的临界阈值,建立瓦斯压力（含量）与动力灾害发生危险性的内在联系。研究成果为深部高瓦斯冲击危险煤层瓦斯抽采前后动力灾害的预测与防治提供科学依据。

深部高瓦斯冲击危险煤层动力灾害的发生形式具有复杂性和多样性，瓦斯压力对煤样冲击性能的影响和控制是动力灾害形式发生转化的主要原因，研究瓦斯作用下煤样冲击性能的变化规律是探索高瓦斯冲击危险矿井动力灾害转化机制的前提基础。项目在瓦斯压力作用下实测了煤样强度参数与冲击倾向性指标，分析了含瓦斯煤样破坏形式与破坏特征的演化规律，研究了冲击倾向性指标对瓦斯压力变化的敏感性，分析了不同瓦斯压力下煤样加载过程中聚能和耗能规律；确定了使不同冲击倾向性煤样冲击性能弱化或消失的瓦斯压力阈值；建立了瓦斯压力作用下煤样冲击性能损伤劣化模型。项目研制了多功能固气耦合试验系统与冲击倾向性型煤配置方法，为研究含瓦斯煤冲击倾向性演化规律提供了实验基础；研发了软弱煤岩层应力连续监测技术与成套装备，实现了原岩应力的长时间连续监测与三维采动应力的监测，填补了高瓦斯软弱煤层中应力测试的技术空白，为研究矿井复合动力灾害发生的应力条件提供了重要支撑；研究表明，瓦斯压力作用下，煤样破坏形式由脆性弹射的冲击破坏向剥离掉落的塑性破坏转变，煤体吸附瓦斯后对其强度产生了软化作用，强度软化和宏观破坏形态的变化说明了煤样失稳形式的转变。基于对强冲击倾向性、弱冲击倾向性型煤的冲击倾向性指标的测试，结果表明随着瓦斯压力增加，煤样峰后振铃次数和能量占比逐渐增加，发生冲击破坏的能力减弱，确定了煤样冲击倾向性跃迁的瓦斯压力阈值，建立了瓦斯压力与冲击倾向性指标的数学拟合关系，初步揭示了高瓦斯冲击危险煤岩灾变转化机制。研究成果为深部高瓦斯冲击危险煤层动力灾害预测与防治提供了研究基础，具有良好的推广应用前景。