【摘要】 在对MTS815岩石伺服试验系统通讯传输接口进行改造的基础上,实现了将检波器置于三轴室内的三轴压缩声发射试验,克服了检波器置于三轴室外壁无法监测到全面可靠声发射信号的弊端.煤岩三轴压缩声发射试验结果表明,与单轴压缩相比,围压增强了煤岩的整体性及刚度,使压密阶段声发射活动明显减弱.声发射振铃计数及能量出现最大值的时间均稍滞后于煤岩宏观破坏时刻,说明围压不但提高了其峰值强度,而且由于围压使煤岩内部裂隙的错动滑移受到抑制,提高了其峰后承载能力.振幅反映声发射的强度,三轴压缩条件下,轴向加载初期声发射振幅较小,宏观破裂前后出现大量高振幅声发射事件,残余塑性阶段仍然有较多振幅较大的声发射事件产生.声发射撞击计数率表征裂纹扩展的次数及速率,三轴压缩声发射撞击计数试验结果表明,弹塑性阶段是煤岩裂隙萌生扩展的主要阶段.岩石三轴压缩破坏声发射特征对于深刻理解矿山井下岩体破坏机理及采用微震监测技术预防相关动力灾害事故具有重要的理论及实际指导意义.更多还原

【Abstract】 Acoustic emission( AE) tests of coal specimens under triaxial compression condition were carried out with AE detector inside the triaxial chamber based on remodelling communication interface of MTS815 rock mechanical test system,overcoming the disadvantages of being unable to monitor the comprehensive and reliable AE signals as the AE detector installed outside the triaxial chamber wall of the rock mechanical test system. Compared with uniaxial compression test,the results of AE tests of coal specimens under triaxial compression show that the integrity and stiffness of the specimens are raised by the confining pressure and the AE activities decrease significantly in the stage of compaction. The time of the AE counts and the AE energy reaching their highest values relatively lags behind the moment of the macroscopic failure of the specimens,which draws the conclusion that the confining pressure can improve not only the specimens’ peak strength but also their bearing capacity after peak stress,because the dislocating and slipping of the internal fractures are restricted by the confining pressure.Amplitude reflects the strength of AE,under triaxial compression condition,the AE amplitudes are relatively low at the initial stage of axial loading,and a large number of AE events with very high amplitudes appear around the moment of the macroscopic failure of the specimens,but there are still a lot of AE events occuring with relatively high amplitudes in the residual plastic deformation stage. The number of AE impact count rates reflects the unmber and rate of the crack propagation,test results of AE impact counts under triaxial compression show that the elastic-plastic stage is the major stage of the inside fractures’ producing and developing of coal specimens. The results of AE characteristic of rock damage failure under triaxial compression are of important theoretical and practical guiding significance for deeply understanding the failure mechanism of rock mass,and preventing the related dynamic disasters underground mines by micro seismic monitoring technology.更多还原