1. State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University, Chongqing　 400044,China; 2. China Coal Research Institute, Beijing　 100013,China; 3. Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan　 430071,China; 4. Department of Earth Sciences, U-niversity of Cambridge,Cambridge　 CB2 3EQ, United Kingdom

为了研究砂岩蠕变过程声发射信号的统计特征,在实验室条件下进行了砂岩的长期和阶梯加载蠕变试验,并采集了全过程声发射信号。利用直方统计和最大似然估计分别分析了声发射能量统计特征,并对破裂断面进行了三维激光扫描重构,结果表明:长期与阶梯加载蠕变具有相似的声发射信号形貌,但是阶梯加载蠕变声发射率明显大于长期蠕变结果;长期蠕变和阶梯加载蠕变所产生的声发射信号的能量概率密度都满足幂律分布,且利用直方统计与最大似然估计两种方法都得到相似的幂律指数,可信度较高。蠕变的幂律指数不同于已有的单轴压缩结果而更接近于地震幂律指数结果;相较单轴压缩的较光滑破裂面,蠕变破坏面光滑度欠缺并伴有阶梯状断痕,和包含弹性-损伤混合纤维的纤维束模型的假设与结果相吻合。

In order to investigate the statistical characteristics of acoustic emission (AE) of sandstone during uniaxial creep,the AE signals have been captured both in long-time and step loading creep tests. Histogram analysis and maxi- mum likelihood method were used to study the statistical characteristics of AE absolute energy respectively. The results show that the AE jerks of long-time and step loading creep tests have similar shape,but the AE rate of step loading was higher than that of long-time test;Both the probability density functions ( PDF) of long-time and step loading creep tests satisfied the power law well,and the exponents came from histogram analysis and maximum likelihood method were very similar. These exponents were much closer to the earthquake results than to the exponent of uniaxial com- pression. Unlike the smooth fracture surfaces of sandstone sample in uniaxial compression,the fracture surfaces in- duced by creep were much coarser and with stepped fractures. These results agreed with the assumptions and results of fiber bundle model with time dependence fiber elements.

重庆市自然科学基金资助项目(cstc2015jcyjA90011)；国家科技重大专项资助项目(2016ZX05045001-005)；国家自然科学基金资助项目(51574150)；

Jiang Deyi,He Yi,Ouyang Zhenhua,et al. Acoustic emission energy statistical properties of sandstone during uniaxial creep and its fracture surfaces morphology[J]. Journal of China Coal Society,2017,42(6):1436-1442.