岩石三轴卸围压破裂失稳的声发射前兆基础实验研究

Abstract: The disasters such as roof falling，rock burst , coal and gas outburst etc. are closely related with the rock mass ruptue instability, which is induced by the stress field disturbing during underground mining and excavating process. Because the majority of underground rock mass is under triaxial compressive state, the basic experimental study on acoustic emission precursor and forcast of rock rupture instability under triaxial compression and unloading confining pressure is of important meanings both in theory and practice to forecast the rupture instability of rock mass with acoustic emission monitoring technology so to prevent the disasters thereby. Based on the reasonable acoustic emission experiment method study of rock rupture instability under triaxial compression, MT815 servo-controlled rock mechanical test system will be used to take out the acoustic emission experiments of rock rupture instability under triaxial compression and unloading confining pressure for typical sedimentary rocks. The inter-relationship between the rock damage evoluting process and the acoustic emission characterization parameters will be revealed and the acoustic emission precursor of rock rupture instability under triaxial compression and unloading confining pressure will be analyzed according to the experiment results. Non-linear dynamics and discrete wavelet transform analysis methods will be used to analyze the catastrophe characteristics of the acoustic emission time(strain) sequence of rock damage and failure process, and the quantitative forecasting method of rock rupture instability under triaxial compression and unloading confining pressure will be studied using acoustic emission parameters ,so to provide the foundation for using the acoustic emission monitoring technology to forecast rock mass rupture instability reasonably.

摘要：冒顶、冲击地压、煤与瓦斯突出等灾害事故均与矿山采掘过程中应力场扰动所诱发的岩体破裂失稳密切相关。由于矿山井下绝大多数岩石处于三轴压缩状态，开展岩石三轴压缩及三轴卸围压破裂失稳的声发射前兆及预测研究，对于采用声发射监测技术预测岩体破裂失稳从而预防相关灾害事故的发生具有重要理论及实际意义。本项目在研究合理三轴压缩声发射实验方法的基础上，采用MTS815岩石伺服试验系统进行矿山典型沉积岩石三轴压缩及三轴卸围压声发射试验，揭示岩石损伤破坏演化过程与声发射表征参数间的内在关系，分析岩石三轴压缩及三轴卸围压破裂失稳的声发射前兆。采用非线性动力学及离散小波变换方法分析岩石损伤破坏声发射参数的时间（应变）序列突变特征，研究采用声发射参数定量预测岩石三轴压缩及三轴卸围压破裂失稳的方法，为采用声发射监测技术合理预测岩体破裂失稳提供基础。

开展三轴卸围压条件下岩石破裂失稳机理、声发射前兆特征及预测研究，对于采用声发射监测技术预测岩体破裂失稳、防止灾害事故发生具有重要理论及实际意义。论文在研究合理三轴压缩声发射实验方法的基础上，采用MTS815岩石伺服试验系统对煤矿沉积岩石进行三轴压缩及三轴卸围压声发射试验，探讨岩石卸围压损伤破坏的力学机理、能量演化规律及分形特征，揭示岩石损伤破坏演化过程与声发射表征参量之间的内在关系，探讨岩石三轴卸围压破坏的声发射前兆，研究采用声发射前兆特征预测岩石三轴卸围压破坏的方法。.针对声发射检波器放置在三轴室外壁无法接收到全面可靠声发射信号的弊端，研制了高围压三轴声发射实验压头，并对MTS815岩石伺服试验系统的通讯传输接口进行改装，实现了声发射信号由三轴室内部向外部的正常传输，确定了合理的三轴压缩声发射实验方法。.根据煤、砂岩、灰岩的常规三轴压缩及三轴卸围压试验结果，分析了岩石在不同卸荷初始围压、不同卸围压速率下的变形破坏特征、强度特征、破碎岩样表面裂纹及破碎块度的分形特征，探讨了常规三轴压缩及三轴卸围压等不同应力路径对岩样力学参数的影响。.通过分析不同卸荷初始围压、不同卸围压速率下岩石卸围压破坏过程的能量演化规律，以能反映岩石破坏本质的耗散能为状态变量分析岩石三轴卸围压损伤演化特征及突变特征，并与常规三轴压缩时岩样的损伤特征进行了对比分析。.根据岩石在不同卸荷初始围压、不同卸围压速率等不同影响因素下的三轴卸围压破坏声发射特征，揭示了煤、砂岩、灰岩三轴卸围压损伤破坏演化过程与声发射各表征参数之间的内在关系，以声发射参数为损伤变量分析了岩石的损伤破坏特征。.基于声发射时间序列的分形与混沌特征，得到了能够反映岩石卸荷失稳破裂的前兆判据，如频谱特征、关联维数、HURST指数、混沌分叉特征等，提出了基于EMA的岩石破裂失稳多源联合分级预测方法。