局部弱化诱发回采巷道围岩整体结构失稳机理研究

The local weakening area extension of roadway surrounding rock often induces roadway whole instability, but the mechanism is not clear. The project takes the whole structure of roadway surrounding rock for research object, and selects roof, floor, chain pillars and coal as basic characteristics structure, which constitute the whole structure of roadway surrounding rock. Analyzing the whole structure relationship and load characteristics of roadway surrounding rock, physical mechanical structure model, corresponding boundary conditions and load conditions are established. Using digital speckle technique, the stress-strain relationship of coal (rock) specimens, failure mode and local weakening strain field information in loading process are determined, local weakening range and the control relationship of local weakening area expansion to basic characteristics structure stiffness weakening are established. According to the corresponding relations between the basic characteristics structure and whole structure, the whole structure stability mathematical model and the whole total stiffness matrix in the influence of local weakening are established. It takes the energy functional quadratic variation as instability criterion and is solved by developing finite element program. Analyzing The similar material experiment and the numerical simulation results, the law that the extension and evolution of local weakening area lead to local instability of roadway surrounding rock, and then induce whole instability of roadway is expounded. It reveals the whole instability mechanism of roadway surrounding rock, and provides a theoretical basis for improving stability control theory of roadway surrounding rock structure.

煤矿巷道围岩局部弱化区域扩展、延伸常诱发巷道整体失稳，但机理尚不清楚。项目以回采巷道围岩整体结构为研究对象，选定顶板、底板、护巷煤柱及煤体为基本特征结构，基本特征结构共同构成巷道围岩整体结构；分析巷道围岩整体结构关系、载荷特征，建立物理力学结构模型，确定边界条件和载荷条件；采用数字散斑技术，测定加载过程中煤(岩)试件应力-应变关系、破坏形态及局部弱化应变场信息，确定局部弱化范围，确立局部弱化区扩展对基本特征结构刚度弱化控制关系；根据巷道围岩基本特征结构与整体结构对应关系，建立局部弱化影响下巷道围岩整体结构稳定性数学模型与整体总刚度矩阵，以能量泛函二次变分为失稳判据，并开发有限元程序求解；分析巷道围岩相似材料模拟试验和数值模拟研究结果，阐明基本特征结构中局部弱化区扩展演化引发巷道围岩局部失稳，进而诱发巷道整体失稳的规律，揭示巷道围岩整体失稳机理，为完善巷道围岩结构稳定性控制理论提供理论基础。

煤矿巷道围岩局部弱化区域扩展、延伸常诱发巷道整体失稳，但机理尚不清楚。项目以回采巷道围岩整体结构为研究对象，采用数字散斑技术测定静态加载和循环加载过程中不同弱面影响下岩样试件应力-应变关系、能量转化关系、破坏形态及局部弱化应变场信息，通过相似模拟试验分析了断层弱化条件下巷道围岩受力及破坏特征，确立了局部弱化区扩展对试件、巷道围岩的弱化控制关系；利用FLAC3D二次开发，设定巷道围岩不同侧压力系数、宽高比、埋深及掘进速度条件，提取出处于弱化区域顶、底板及帮部围岩范围的弹性应变能密度和能量释放密度，利用尖点突变理论建立能量释放数学关系，确立能量二次变分为局部诱发巷道整体失稳的判据。提出局部弱化条件下巷道稳定控制思路，提出了预留泡沫混凝土变形层复合支护方法，通过数字散班采集加载条件下相似模型应变场信息，同时分析提取围岩应力变化规律，验证复合支护方法对围岩弱化区扩展抑制作用。提出“卸压效率”的概念，确定围岩应力与卸压效率之间的关系，用于复合支护结构优化。研究丰富了巷道围岩稳定性控制措施，为局部弱化条件巷道围岩稳定性控制提供了科学依据。