小浪底细砂岩单轴压缩声发射特征研究

采用岩石伺服试验机和声发射仪，对小浪底三叠系细砂岩进行单轴压缩声发射试验。基于试验结果，将试样变形过程划分为压密、弹性、塑性和破坏四个阶段，分析了不同阶段试样声发射幅值、峰值频率、振铃计数和能量的变化特征，在此基础上对比分析了试样声发射ｂ值以及累计振铃计数的演化规律，得出了岩石的破坏时间前兆特征。研究结果表明:压密和弹性阶段试样声发射幅值、振铃计数和能量处于较低水平、峰值频率频带数量依次增多；塑性阶段试样幅值增大、振铃计数与能量上升且整体处于较高水平、峰值频率数值增大且呈现多频带化，临近破坏阶段试样产生大量100ｄＢ的高幅值信号，振铃计数与能量持续急增，峰值频率降低，频带减少；声发射ｂ值的变化规律可以间接反映岩体内部微裂隙萌生、扩展的演化特征。

Uniaxial Compression Acoustic Emission Characteristics of Fine Sandstone at Xiaolangdi

Uniaxial compression acoustic emission test of Triassic fine sandstone at Xiaolangdi was carried out by using rock servo testing machine and acoustic emission instrument.Based on test results from the samples,the deformation process is divided into pressure,elasticity,plasticity and damage four phases.The different stages of acoustic emission peak amplitude,frequency,sample ringing counts and energy characteristics was analyzed based on the analysis of the acoustic emission sample b value and the cumulative ringing count the evolution law of the damage time precursory characteristics of the rock are proposed.The results are as follows.Acoustic emission amplitude,ringing count and energy are at a low level,and the number of peak frequency bands increases successively at the compaction and elastic stage.In the plastic stage,the sample amplitude increases,the ringing count and energy rise and the whole is at a high level,the peak frequency value increases and presents multi-frequency band.Near the failure stage,the sample generates a large number of 100 dB high-amplitude signals,the ringing count and energy continue to increase sharply,the peak frequency decreases and the frequency band decreases.The variation law of AE b value can indirectly reflect the evolution characteristics of the initiation and expansion of micro-fractures in rock mass.