砂岩单轴蠕变声发射能量统计与断面形貌分析

发布时间：2018-05-18 23:43

本文选题：蠕变 + 声发射　；参考：《煤炭学报》2017年06期

【摘要】：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。
[Abstract]:In order to study the statistical characteristics of acoustic emission (AE) signals in sandstone creep process, long-term and step loading creep tests of sandstone were carried out under laboratory conditions, and acoustic emission signals were collected from the whole process. The statistical characteristics of acoustic emission (AE) energy are analyzed by means of straight square statistics and maximum likelihood estimation, and the 3D laser scanning reconstruction of the fracture section is carried out. The results show that the long-term creep has the same shape as the stepped creep. However, the acoustic emissivity of step loading is obviously higher than that of long term creep, and the energy probability density of acoustic emission signals generated by long term creep and step loading creep both satisfy the power law distribution. The power law exponents are obtained by using the methods of direct square statistics and maximum likelihood estimation, and the reliability is high. The power law exponent of creep is closer to the result of seismic power law exponent than that of uniaxial compression, and the smoothness of creep failure surface is less than that of uniaxial compression, and the creep failure surface is accompanied by ladder fracture mark. The hypothesis of the fiber bundle model with elastic-damage mixed fibers is in agreement with the results.
【作者单位】：重庆大学煤矿灾害动力学与控制国家重点实验室;煤炭科学技术研究院有限公司;中国科学院武汉岩土力学研究所;剑桥大学地球科学系;
【基金】：重庆市自然科学基金资助项目(cstc2015jcyj A90011) 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)
【分类号】：TD315

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