冲击扰动下深部块系岩体滑移型岩爆的诱发机理及能量判据研究

Under high geostress, structural surfaces of blocky rock masses are often in a subcritical equilibrium state. external impact disturbance can easily trigger slip failure of structural surface, which is usually known as a slip type rock burst. Slip type rock burst can bring a large energy release，which makes it a direct threat to the safety of construction workers and engineering equipment. However, owing to the complexity of the physical mechanism, the prediction of slip type rock bursts is very difficult. With experimental and theoretical studies, this project intends to carry out research on the most urgent issues of mechanism and prediction of slip type rock bursts. Based on the self-developed test system for dynamic mechanical properties of blocky rock masses, indoor tests of blocky rock model will be carried out. Under impact disturbance, characteristics of the wave velocity spectrum and laws of energy transfer and attenuation of pendulum type waves in blocky rock masses will be studied. Relationship between shear strength and cumulative displacement along structural surfaces will be obtained. The effects of initial stress, structural surface properties and impact disturbance on the shear weakening effect, energy threshold of structural surface slip failure and rock ejection kinetic energy in the process of slip-type rock bursts are revealed. The calculation model of the slip stability of blocky rock masses is established, and, based on the calculation model, the energy criterion of the slip-type rock burst is deduced. Expected results can be used to interpret the physical mechanism of underground explosion-induced slip type rock burst and optimize design methods of deep tunnel supports. In addition, these results can provide theoretical support for deep underground protection engineering siting and safe depth calculation.

高地应力条件下块系岩体结构面往往处于亚临界平衡状态，外界冲击扰动极易诱发结构面滑移破坏发生滑移型岩爆，释放出巨大能量，直接威胁人员生命及设备安全。然而滑移型岩爆诱发机制复杂，使其预测、预报十分困难。项目针对亟待解决的岩爆机制及判据问题，通过试验与理论研究相结合的方法，借助自主研制的块系岩体动态力学性能测试试验系统，开展块体模型的室内试验，研究冲击扰动下块系岩体中慢速变形波的波速频谱特征、能量传递及衰减规律；获得结构面剪切强度和累积位移的内在关系；揭示初始地应力、结构面性质和冲击扰动对滑移型岩爆发生过程中结构面剪切弱化效应、结构面滑移失稳能量阈值及岩块弹射动能的影响机制；构建块系岩体滑移稳定性的计算模型，并据此推导滑移型岩爆的能量判据。预期成果可用于解读地下爆炸诱发滑移型岩爆的物理机制、优化深埋巷道的抗冲击支护设计方法，也能对深地下防护工程的选址、安全埋深设计提供理论支撑。

高地应力条件下块系岩体结构面往往处于亚临界平衡状态，外界冲击扰动极易诱发结构面滑移破坏发生滑移型岩爆，释放出巨大能量，直接威胁人员生命及设备安全。本项目围绕滑移型岩爆机理及诱发条件展开，利用自主研制的“块系构造岩体动态力学性能测试试验系统”进行了冲击扰动诱发滑移型岩爆的室内模拟试验，建立了冲击扰动下滑移型岩爆动力计算模型，编制了MATLAB程序进行数值计算，推导了块系岩体不可逆位移及滑移型岩爆的能量条件。得到的结论主要有：.（1）在外部冲击扰动作用下，岩块的位移和加速度均随比例距离按指数形式衰减。冲击应力波在块系岩体中传播时，传播速度远远小于连续介质中的纵波速度，能观察到加速度频谱由高频向低频转化，振动的极值频率满足定量的规范序列关系。.（2）外部冲击扰动导致岩块间的超低摩擦效应，当岩块间摩擦力小于剪切力时，块体沿着结构面运动产生不可逆的滑移运动。冲击扰动诱发的岩块间的滑移运动与岩块初始剪切应力水平密切相关。在亚临界状态，极其微弱的扰动即可诱发较大的岩块间位移，甚至产生持续性的滑移直至失稳，发生滑移型岩爆；当初始剪切力小于岩块间动摩擦强度时，瞬时冲击扰动很难诱发岩块间的动力滑移失稳，只能诱发不可逆位移。.（3）多次扰动试验表明，更大的冲击能量和水平拉力将加速位移的累积，需要更少的扰动次数能诱发滑移型岩爆。试验中没有明显证据表明冲击频率提高会促进滑移型岩爆的发生。多次扰动所需的临界能量条件更低，更容易诱发岩块的滑移失稳。.（4）滑移型岩爆产生需要满足三个条件：工程岩体中存在软弱结构面（内因），结构面上的应力条件接近临界状态（外因），动力扰动使得结构面抗剪强度降低（诱因）。.（5）通过引入无量纲参数，分析了岩块开始滑动和滑移失稳的能量条件，获得了滑移型岩爆诱发所需能量对结构面剪切强度变形特征、摩擦系数、岩块尺度等参数的依赖关系。