深部硬岩岩爆发生机理及协同预警关键点识别研究

In deep hardrock mine, the challenge is existed for rockburst, such as the unclear occurrence mechanism, difficult identification of early-warning key points, unreliable criterion and poor effect. In this study, the aim is to investigate the occurrence mechanism of rockburst and establish an initial system of synergetic early warning using several methods. The main research work includes: (1) Using the CT technique and microseismic mornitoring system, the microstructure instability of rock under loading and unloading is detected to analyze the evolution laws and characteristic of microseismic events. Based on this, the nonlinear dynamics theory and statistical methods are used to build the universal evolution model and the characterization parameters. (2) Based on the coal or rock burst failure imaging system and the high-speed imaging system, The discriminative model and criterion of stress-energy in the process of disaster will be explored to clarify the stress-energy mechanism of rockburst. (3) the dynamic Bayesian self-adaptive modeling method are used to establish the dynamic adaptive model for the evolution of rockburst. The time-stress-energy-instability nonlinear dynamic evolution model will be built for the early warning of rockburst. The aim is to distinguish the main control factors and disaster inducing factors of rockburst. A rockburst hazard potential mode will be created. According to the field monitoring and the laboratory experiment, the feature of particle vibration velocity and disaster inducing potential will be analyzed for recognizing the early-warning key points based on several methods, the graded method of early warning will be presented. The field monitoring data is used to verify and optimize the established early-warning model and form the initial intact system of synergetic early warning of rockburst.

深部硬岩岩爆存在发生机理不明确、预警关键点难识别、判据不可靠及效果差等难题。本研究以探明其发生机理及实现多手段协同预警初步体系为目的，主要开展以下工作：(1)基于CT 技术和微震测试系统，采用非线性动力学和统计学方法，分析加卸载岩石细观结构失稳微震事件演化规律及特征，构建具有普适意义的演化模型并进行参数表征；(2)基于煤岩冲击破坏图像系统及高速成像系统，探讨岩爆演化过程应力-能量判别模型和准则，揭示应力-能量发生机理；(3)采用动态贝叶斯网络自适应建模方法，建立岩爆演化动态适应性模型，构建岩爆的时间-应力-能量-失稳非线性动力学演化预警模型，找出主控因素，进行致灾因子识别，创建岩爆致灾潜能模式；开展现场和室内试验，分析岩体的质点振动速度特征及其致灾潜能，进行多手段协同预警关键点识别，提出预警等级划分方法。利用现场实测数据，对预警模型进行校验和优化，形成较为完善的岩爆多手段协同预警体系雏形。

针对目前深部硬岩岩爆存在失稳前兆信息表征困难，发生机理不明确、预警关键点难识别、判据不可靠及效果差等难题，本研究开展理论分析与试验研究。. 本研究发现声发射空间分维随应力水平的增大呈线性减小；以声发射累积能量、时间为表征，得到了破裂面时-空-能演化模型。基于CT图像对试件进行三维重构，建立了应力-裂纹分形维数值的系统熵模型，描述了岩石裂纹扩展演化规律；以裂纹的长度、面积及其分形维数参数对岩石裂纹演化失稳过程进行表征，构建的裂纹生长因子模型具有混沌特征。. 对硬岩变形破坏过程和特征进行分析，以马克斯韦尔体并联弹塑脆性体损伤分支，构建的弹性-损伤-塑性本构模型符合硬岩破坏特征。以系统刚度、岩石聚集静态能与裂纹扩展能量、峰值应力应变与弹性模量关系为失稳判据，构建了“应力-能量-刚度-损伤”岩石断裂破坏的多准则体系。对深井硬岩岩爆的应力-能量发生机理进行阐述，认为硬岩处于高度的集中应力状态和储存有大量可释放的应变能时会孕育发生岩爆。. 确定相对平静期在峰值应力88%至98%之间。将临近强度极限的b值下降作为预警前兆；破裂前红外热像出现“升-降-升-降”的异常现象，认为平均温度由上升到降低转折点是预警点，由下降到上升的转折点为关键预警点，在85.2%至89%峰值强度区间，破坏时平均温度升高约2℃；AE主频熵值出现“震荡-上升-剧烈下降”的现象，将熵值极大值作为预警点；分别将循环加卸载响应比值降低至1的点和切线模量斜率减小的拐点作为预警关键点；根据TDF变化，以75%，83.3%和91.7%应力值将预警划分为红黄蓝三个等级；在MS活动率下降和累计视体积急剧增加后，将相对平静期的开始作为预警关键点。基于现场数据建立贝叶斯预警模型判断岩爆发生概率，准确率为94%；建立模糊元预警模型对预警进行分类。以上述方法为基础，建立预警试验系统，实现多手段监测协同预警。