三轴压缩煤岩破裂过程中声发射时空演化规律

利用MTS815岩石力学实验系统，开展不同围压（3.2、9.6、16.0、22.4 MPa）下煤岩的三轴压缩声发射定位实验，研究煤岩破裂过程中AE(Acoustic Emission)时序特征、能量释放与空间演化规律。实验发现：静水围压阶段，AE信号主要产〖JP2〗生于中前期，声发射源主要是裂隙的压密、摩擦与滑移，其强弱与试件的原生裂隙、孔隙的发育程度密切相关；施加轴压阶段，煤岩声发射时空演化过程与应力应变曲线具有良好的对应关系，在产生初始损伤、屈服及破坏时，AE特征均会产生明显的突变。AE时序参数、能量释放与定位信息的综合分析表明，煤岩破坏前兆点的应力强度百分比为92%~98%，均处于屈服点后的不稳定裂纹扩展阶段。同时，实验揭示了煤岩破裂过程中声发射的围压效应，并发现AE时空定位演化较好地对应了破裂事件从单一到复杂、从无序到有序的演化过程。

Space-time evolution rules of acoustic emission locations under triaxial compression

To study AE space time evolution rules and energy releasing characteristics during deformation and failure process of coal，a series of triaxial compression tests were carried out by MTS815 rock mechanics test system at different confining pressures，i.e.3.2，9.6，16.0 and 22.4 MPa.The test results find out that，during hydrostatic confining pressure phase，AE signals mainly occurre at the preliminary and medium stage and closely related to the native fissures and pores，and originated mainly from compaction，friction and slip of the fissures；during the stage of axial compression，the space time evolution corresponds well to the stress strain curves.The characteristics of acoustic emission are significant when the specimen initially damaged，yield and destroyed.Based on the analysis of AE time series parameters，energy release and the location points，it is found out the ratio of stress at coal failure precursor to peak stress is from 92% to 98%.The experiment also reveales the confining pressure effects of AE during the failure process of coal.Meanwhile，AE space time evolution corresponds well to evolution process of fracture events which emergs from single to complex and from disorder to order.