高应力下卸荷及动力扰动作用诱发断裂滑移型岩爆机理和预警研究

The stress state on the fault can be changed due to the excavation unloading and dynamic disturbance in deep rock engineering, leading to fault reactivation and fault slip rockburst. In this project, true triaxial loading-unloading test and dynamic disturbance test will be conducted on granite joint, and influences of intermediate principal stress, unloading rate, amplitude and frequency of dynamic loading on the failure modes, shear strength, stress drop and energy release will be investigated. Moment tensor analysis on AE events will be performed to illuminate the type and sequence of micro-fractures in asperities of joint, and its influence on the macro-failure. Scanning electron microscope and thin section observation will be used to study the crack distribution on the fault surface and its relation with mineral types after shear failure. The mechanism of fault slip rockburst induced by unloading and dynamic disturbance will be revealed by these macro and micro methods. A new joint shear strength model which considers the effect of intermediate principal stress will be proposed based on the experimental data. The new model as well as the calculation formulas of seismic radiation energy and moment magnitude during fault slip will be coded in FLAC3D, and the numerical analysis method of fault slip rockburst will be developed. The variation of acoustic emission parameters, especially the AE b-value and the temporal and spatial fractal dimensions with shear time and stress level will be analyzed in detail, and a prediction method of fault slip rockburst will be proposed based on the numerical simulation and AE monitoring.

深部岩体工程中，开挖卸荷或爆破扰动会改变结构面上的应力状态而导致其活化，从而诱发断裂滑移型岩爆。本项目通过对含结构面的花岗岩开展真三轴加卸荷试验和动力扰动试验，研究中间主应力、卸荷速率、动力扰动幅值和频率等对结构面破坏模式、剪切强度、峰后应力降和能量释放量的影响；采用矩张量对定位的声发射事件分析，阐明起伏体内微破裂的种类、起裂顺序和对宏观失稳的影响，通过扫描电镜和岩石薄片显微观察对破坏后的断层面取样观察，分析断层面裂纹分布与矿物类型的关系，揭示卸荷和动力扰动诱发断裂滑移型岩爆的内在机制。根据试验数据，建立考虑中间主应力效应的峰值剪切强度模型，基于FLAC3D和地震学原理，将新模型以及地震辐射能、矩震级等表征岩爆强度的参数程序化，建立断裂滑移型岩爆的数值分析方法；总结分析声发射b值、时空分形维数等参数随结构面突然错动失稳的前兆特征规律，构建基于声发射监测和数值仿真的断裂滑移型岩爆预警方法。

本项目以深部隧洞施工过程中频繁发生的滑移型岩爆为研究对象，以室内试验为主要研究手段，研究了低频扰动和高速率冲击扰动作用对结构面滑移失稳的影响，探讨了扰动作用影响下滑移型岩爆的发生机制；采用直剪试验揭示了温度对花岗岩结构面峰值剪切强度、峰后应力降、粘滑幅值和粗糙度劣化程度的影响特点；采用宏观粗糙度表征、细观显微镜观察、声发射、DEM模拟等多手段结合、多角度揭示了高应力下硬岩结构面宏细观损伤特点，探讨了细观损伤对宏观动力学失稳的影响；分析了岩石II型应力应变曲线的发生机制和影响因素，为将II型曲线应用于岩爆等动力灾害的评估提供了理论支持。在国际权威期刊发表高水平SCI收录论文16篇（一作或通讯作者11篇）、授权发明专利1项，入选山东省省级人才工程项目1项，在国内外岩石力学学术会议上做报告6次，培养硕士研究生7名、博士研究生2名，硕士毕业生获得校级优秀学位论文1项。