煤样剪切试验微震响应小波包能谱特征

    Characteristics of Wavelet Packet Energy Spectrum by Micro-seismic Activities of Coal Samples Under Shear Tests

    • 摘要: 选取煤体试样,采用装备ESG微震监测系统的日本岛津公司生产的AG-I250KN型精密电子万能材料试验机,分析在剪切模式下,煤样强度及变形破坏特征,运用小波包能量谱理论,提取突变信号的频带能量和事件数,获得了煤样剪切条件下的应力应变曲线以及应力应变过程曲线中4个阶段的微震响应特征;在初始压密和弹性阶段,没有微震信号、频带归一化能量为0、事件数为0;在应力屈服阶段,微震信号多、频带归一化能量大、有大量事件数产生;在破坏阶段,微震信号丰富、频带归一化能量达到峰值后降低、事件数减少。分析得出煤样破裂微震信号频率响应主要集中在625~1 000 Hz。

       

      Abstract: Selecting typical coal samples and the Shimadzu AG - I250KN precision electronic universal material testing machine equipped ESG micro-seismic monitoring system, the characteristics of coal strength and deformation were analyzed under the loading mode. The frequency band energy and micro-seismic events were extracted by wavelet packet energy spectrum theory; the stress-strain curves of coal samples under shear as well as the characteristics of micro-seismic signals at four stages of the stress-strain curve were obtained. It is found out that micro-seismic signals seldom occur in the initial consolidation and the elastic stage, the frequency band energy is zero, no events produce; the micro-seismic activities instantly occur in the yielding stage, the frequency band energy increases until up to the peak at the end of the maximum compressive strength, a large number of events generate; the micro-seismic signals are rich, the normalization of frequency band energy reduces in the broken stage, the number of events is lower after arriving the peak. It shows that the frequency range of micro-seismic activities are mainly concentrated from 625 Hz to 1 000 Hz.

       

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