深部开采动力扰动下底板应力演化及裂隙扩展机制

Crack propagation mechanisms and stress evolution of floor under dynamic disturbance in deep coal mining

深部开采地应力增高及动力灾害增多驱动岩体裂隙扩展导致底板突水事故频发,使得研究动力扰动下裂隙扩展机制具有指导意义。根据弹性理论推导分析了顶板动力扰动对底板应力的影响,模拟计算了动力扰动下底板应力及位移演化规律,基于卸荷岩体理论分阶段研究了动力扰动下端部效应区及卸荷作用下突水通道发育区的裂隙扩展机制,结合岩体渗流特征分析了高承压水压力下裂隙的渗透作用,并进行了工程验证。结果表明：随动力扰动强度增加,端部效应区应力非线性增长;动力扰动强度越大,卸荷起点越高,越易满足裂隙扩展的临界应力;动力扰动强度决定了底板裂隙的扩展及渗透作用机制,当突水通道发育区渗透率突变增加的岩层深度大于隔水层厚度时将诱发底板突水。

Inrush accidents are easily and frequently caused under high geostress and rising of dynamic disasters which induce crack propagation of rock mass in deep coal mining. So it is important to study the crack propagation mechanisms under dynamic disturbance. According to the elastic theory, the influences of dynamic disturbance of roof on stress of floor are analyzed. The evolution of stress and displacement under dynamic disturbance is simulated. Based on the unloading rock mass mechanics, the propagation mechanisms of cracks in the bottom effect zone under dynamic disturbance and inrush channel development zone under unloading are studied by stages, and the penetration effect of cracks is explored based on the seepage characteristics of rock mass under confined water pressure, and then engineering verifications are carried out. The results show that with the increasing dynamic disturbance intensity, the stress in the bottom effect zone increases nonlinearly. The larger the dynamic disturbance intensity, the higher the starting points of stress unloading, and it easily meets the critical stress of instability propagation of cracks. The dynamic disturbance intensity determines crack propagation and seepage mechanisms, and when the stratum depth of permeability suddenly increased in the inrush channel development zone is larger than the thickness of aquiclude, water inrush of floor will be induced.