深部硬岩开挖卸荷的动态响应机理研究

The project focuses on the dynamic unloading process of deep underground excavation in the hard rock, which will be comprehensively investigated by the theoretical analyses, laboratory experiments, numerical simulations and field tests. Based on the elastodynamics and the method of mathematical physics, the dynamic unloading mechanism will be demonstrated by a mathematical physics model, which can describe both the time-varying stress and displacement responses of the surrounding rock and the unloading disturbance features in the far field. In addition, the true triaxial unloading tests under different unloading rates will be conducted to explore the damage mechanics behavior and the fracturing mechanism by the measurement of the real-time dynamic response, crack propagation and acoustic emission characteristics. A numerical simulation model will then be implemented to reproduce the surrounding rock failure characteristics and the far-field unloading waveform under different unloading conditions. Furthermore, the dynamic stress path evolution of the deep rock mass under the influence of excavation will be obtained, and the energy feedback characteristic and storage-release mechanism will be investigated. Finally, the field tests will be carried out and a comparison between the theoretical analyses, the numerical simulations and the test results will be conduted to reveal the dynamic response mechanism of the excavation unloading disturbance in the deep hard rock. Therefore, the project will provide theoretical basis for the disaster control in the deep rock engineering, the shape design of the deep engineering, and the optimization of the support pattern and the excavation method.

本项目针对深部硬岩矿山工程的动态卸荷过程，综合运用理论分析、室内实验测试、数值仿真和现场试验等手段进行了研究。首先，基于弹性动力学和数学物理方法等理论，构建动态开挖卸载的数学物理模型，同时反映工作面围岩应力和位移的时程变化和远场卸荷扰动的波形特征；在此基础上开展考虑不同卸载速率的高应力岩石真三轴卸载试验，实时监测岩石的动力响应、裂纹扩展和声发射特征，揭示高应力动态卸载下岩石的破坏力学特性和破裂机理；结合深部岩体开挖卸荷数值模拟实验，再现不同卸荷工况下的围岩破坏特征和卸荷扰动效应，获得采动影响下深部岩体的动态应力路径演化规律，阐明开挖过程的能量反馈特征和储存-释放机制；最后进行现场试验,将试验结果与理论分析和数值模拟对比分析，从而揭示深部硬岩开挖卸荷的动态响应机理。本项目将为深部岩体工程的灾害控制、工程断面形状设计、支护方式和开挖方式优选等提供理论依据。

深部岩体在开挖过程中，不仅要承受高地应力，还受到开挖卸荷等动力扰动的作用，这种卸荷扰动使得深部围岩表现出与浅部岩体不同的力学特性。然而，现有研究主要关注的是深部岩体开挖前后应力状态的改变对围岩力学特性的影响，较少关注卸荷过程的影响。基于此，本项目综合运用理论分析、数值模拟和室内试验等研究手段，对深部高应力硬岩的动态开挖卸荷过程进行了深入研究。主要研究工作和结果如下：（1）研究了深部高应力硬岩巷道开挖卸荷的动态响应机理，建立了巷道动态开挖卸荷的数学物理模型，分析了卸载速率、卸载路径、地应力水平、侧压力系数和巷道截面形状的影响；结果表明，高地应力的快速卸荷会激起显著的动态效应，非线性卸荷引起的动态响应大于线性卸荷引起的；研究结果能够为深部巷道开挖设计提供理论依据。（2）研究了深部巷道在含结构面岩体中开挖引起的围岩破坏机理，分析了结构面参数和侧压力系数的影响；研究结果为深部巷道在含非连续结构面岩体中的开挖设计提供了科学指导。（3）在深部诱导致裂的指导思想下，研究了非爆开挖卸荷下高应力硬岩的力学特点和破裂机理，分析了掘进速度、开挖高度和预裂隙的影响；结果表明，可以通过调整掘进速度、控制开挖高度和添加预裂隙等方法诱导高应力岩体破裂，从而实现非爆机械化连续开采的科学设想。（4）开展了高应力硬岩的真三轴卸载试验，分析了试样高宽比和中间主应力的影响；结果表明，随着试样高宽比的减小和中间主应力的增加，试样破坏模式由剪切破坏向板裂化破坏转变，这揭示了深部开挖工程中板裂化岩爆的发生机理。（5）研究了开挖卸荷扰动和爆破扰动对邻近巷道的作用机理，分析了卸载速率、爆破波参数和地应力的影响，提出了深部巷道动态破坏的判断准则；研究结果从能量演化的角度揭示了深部巷道的动态破坏机理，为深部巷道的动力支护设计提供了理论依据。