高应力下瞬态开挖诱发岩体损伤机制及其演化规律

Stress unloading induced by deep excavation is the main inducing factor leading to the surrounding rock damage, and the dynamic evolution law of damage is of vital significance to reveal the mechanism of deep geological disasters. With combined measurements such as multi-dimensional and multi-scale experiments, theoretical analysis and numerical simulation, this project makes in-depth research on the damage mechanism of deep rocks induced by excavation and macro-microscopic characterization of dynamic damage evolution. Firstly, based on theoretical and experimental studies on surrounding rock damage induced by drilling and blasting excavation in deep tunnels, the formation mechanism of excavation damage zone under transient unloading will be revealed, and a theoretical model of surrounding rock damage zone induced by transient unloading in high stress conditions can be established. Then, with the digital image correlation and micro-CT scanning technology, the stress redistribution and the displacement evolution characteristics of surrounding rocks will be investigated, and a criterion for rock mass damage based on the displacement field characteristics can be developed, which can precisely reveal the damage evolution the of the surrounding rocks under transient unloading. Furthermore, a series of dynamic tests of damaged rock mass will be conducted under dynamic disturbance conditions, to study the superimposed damage evolution mechanism of surrounding rocks under high stress and strong disturbance. According to the theoretical models and the numerical simulation results, a quantitative analysis method of the distribution characteristics of the deep excavation damaged zone will be proposed, which can be used to optimize the support design. The research results can provide theoretical support for the deep rock engineering design and stability evaluation.

开挖卸荷是深部围岩结构损伤的主要诱因，而岩体损伤的动态演化机制是揭示深部地质灾害致灾机理的关键因素。本项目基于多维多尺度试验、结合理论分析和数值模拟，针对高应力下瞬态开挖诱发围岩损伤机理、损伤动态演化的宏微观表征等进行深入研究。通过试验模拟深埋洞室钻爆法瞬态开挖所导致的围岩损伤，揭示围岩开挖损伤区形成的力学机制，建立高应力下瞬态卸荷诱发围岩损伤力学模型。基于数字图像相关和X射线微米CT扫描技术，研究洞室开挖围岩应力重分布特征与位移场演化规律，建立基于表面位移场特征的岩体损伤判据，准确揭示瞬态卸荷作用下围岩损伤的动态演化规律。进一步开展动力扰动下损伤围岩动力学响应试验，研究高应力强扰动条件下围岩损伤区叠加损伤演化机制。提出高应力瞬态开挖下围岩损伤区分布特征的定量分析方法，并根据理论模型及数值计算探讨开挖卸荷及动力扰动下深部岩体稳定性。研究成果将为深部岩体工程设计及稳定性评价提供理论支撑。

开挖卸荷是深部围岩结构损伤的主要诱因，而岩体损伤的动态演化机制是揭示深部地质灾害致灾机理的关键因素。本项目基于多维多尺度试验、结合理论分析和数值模拟，针对高应力下瞬态开挖诱发围岩损伤机理、损伤动态演化的宏微观表征等进行深入研究。首先开展了系列的动力学测试获得了不同类别岩石材料的动态响应（压缩、拉伸以及断裂）特征，厘清了动态荷载下材料的损伤以及破坏机理。项目组还发展了模拟脆性材料动态裂纹扩展的非连续变形分析以及离散元分析方法，同时，基于动力学实验的相关结果发展了考虑岩石材料强度等率相关性的破坏准则，为揭示瞬态开挖卸荷后隧道围岩开挖损伤区（EDZ）形成和演化的微观机制提供了工具以及更为真实的分析方法。之后，借助自主研发的模拟硐室掌子面开挖瞬态卸荷的试验系统，系统的研究了不同应力条件下单隧道、多隧道瞬态开挖卸荷后围岩的动态响应（位移、应力振动速度等）规律。最后，利用该实验系统开展了物理模型实验，探讨了瞬态卸荷条件下围岩的损伤和破坏演化特征。研究成果将为深部岩体工程设计及稳定性评价提供理论支撑。