砂岩单轴压缩破坏的临界慢化特征

为了从临界慢化的角度研究岩体破裂失稳产生的声发射信号特征，进行了砂岩单轴压缩实验。基于临界慢化原理，对砂岩单轴压缩破坏产生的声发射信号进行了处理分析，结果表明:在整个加载过程中，砂岩破坏产生的声发射信号呈现出明显的阶段性特征；不同的窗口长度、滞后步长对于表征砂岩破坏临界慢化临界点的自相关系数及方差的波动稳定性有影响；可以将砂岩加载破坏过程中产生的声发射计数自相关系数、方差的突然增大作为砂岩破坏的前兆特征，相对于自相关系数而言，方差更具明显性，且前兆点无论是在时间上还是应力上都达到了总时间及应力峰值的80%以上，具有较好的时效性。

Critical slowing characteristics of sandstone under uniaxial compres-sion failure

In order to study the characteristics of acoustic emission of rock burst failure in the perspective of critical slowing,the experiment of sandstone uniaxial compression was carried out.Based on the theory of critical slowing,the acoustic emission signals generated by uniaxial compression failure of sandstone were analyzed.The results show that the acoustic emission signals produced by sandstone destruction can reflect the obvious characteristics of the stage during the whole loading process.Different window lengths and lagging steps have effects on the volatility stability of the autocorrelation coefficient and the variance of the critical slowing point of sandstone failure.The sudden increases of the autocorrelation coefficient and the variance can be used as the precursor of sandstone damage.Compared with the autocorrelation coefficient,the variance is more obvious in the early warning,and the precursor point reaches more than 80% on the total time and the peak stress,with a good timeliness.