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基于声发射幅频分布的大理岩岩爆试验研究

Experimental study on rockburst test of marble based on acoustic emission amplitude-frequency distribution

  • 摘要: 为了对岩爆前后声发射信号在幅值、主频方面的分布规律进行对比分析研究,探究大理岩在岩爆破坏阶段产生的声发射信号本质特征以及大理岩岩爆破坏产生的内在规律,采用三向加载和单面卸载的方式模拟岩石的应力状态变化过程,将大理岩制成标准的试件并开展了2例岩爆模拟试验,采集了试验过程中的三向应力时程曲线和声发射信号,通过分析三向应力时程曲线将岩爆试验过程划分为加载初期、加卸载阶段和岩爆阶段3大阶段,并对比分析了不同试验阶段内的声发射信号在幅值和主频方面的分布规律,同时提出了声发射信号在幅值-主频平面内分布密度的概念,分析了岩爆前后声发射信号在幅值-主频平面内的分布规律,得到了不同试验阶段声发射信号在幅值-主频平面内的密度最大位置,研究了大理岩发生岩爆的内部破坏规律。研究结果表明:大理岩发生破坏的声发射本征固有频率在以90 kHz和270 kHz为中心的2个频率带中,不随加载应力的变化而发生变化;不同阶段的幅值-频率分布规律有明显区别,岩爆阶段的声发射事件密度最大处对应的主频不小于加载阶段,岩爆阶段出现声发射最高幅值,岩爆阶段的声发射平均主频在200 kHz以上,岩爆阶段的声发射最高幅值和平均主频均大于加载阶段,表明了岩爆阶段岩石发生了更加剧烈的破坏。

     

    Abstract: In order to carry out comparative analysis on the distribution of amplitude and main frequency of acoustic emission signals before and after rockburst, and to explore the essential characteristics of acoustic emission signals generated by marble in the rock burst stage and the inherent law of rock burst, this paper employed the three-way loading and one-way unloading methods to simulate the stress state change process of rock. Two marble rock burst simulation experiments were carried out on standard specimens. Three-dimensional stress time curve and acoustic emission signal were collected during the experiment. The rockburst experiment process was divided into three stages:initial loading stage,loading and unloading stage and rockburst stage by analyzing the three-way stress time-history curve, and the amplitude and frequency of the acoustic emission signal in different experimental stages were compared and analyzed.In terms of the distribution law, the concept of density distribution of acoustic emission signals in the amplitude-frequency plane was proposed. The distribution law of acoustic emission signals in the amplitude-main frequency plane before and after rock burst was analyzed.The internal destruction law of rockburst occurred in marble was studied when the density of the transmitted signal was the highest in the amplitude-main frequency plane. The results show that the intrinsic natural frequencies of acoustic emission of marble failure do not change with the change of loading stress in the two frequency bands centered at 90 kHz and 270 kHz, and the distribution law of amplitude-frequency in different stages has obvious difference.The highest frequency of acoustic emission events in the rockburst stage is not less than that in the loading stages, and the highest amplitude of acoustic emission occurs in the rockburst stage. The average main frequency of AE in rockburst stage is more than 200 kHz, and the maximum amplitude and average main frequency of AE in rockburst stage are larger than those in loading stage, which indicates that the rock in the rockburst stage has undergone more severe damage.

     

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