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水力发电学报 ›› 2019, Vol. 38 ›› Issue (7): 110-120.doi: 10.11660/slfdxb.20190711

• • 上一篇    

基于声发射技术的含裂纹石膏试件破坏分析

  

  • 出版日期:2019-07-25 发布日期:2019-07-25

Failure analysis of pre-cracked specimen based on acoustic emission technique

  • Online:2019-07-25 Published:2019-07-25

摘要: 受压条件下岩体破坏规律是岩石力学的重点课题之一。本文采用含裂纹石膏试件模拟天然裂隙岩体,分别对不含预制裂纹,含0°、30°、45°、60°、90°预制裂纹的石膏试件进行单轴压缩试验,运用声发射和波速监测技术研究其破坏特性和损伤机制。对声发射信号进行了频谱分析,揭示了石膏材料主频在500 kHz以下,而噪声信号主频在500 kHz以上的特点,基于此进行了去噪;设定参数HPS评价声发射强度,把预制裂纹试件的破坏模式归类为3类:压碎(0°)、压剪(30°、45°、60°)和劈裂(90°及无裂纹);提出利用多元回归分析改进声发射时差定位算法,取得了良好的定位效果;采用纵横波波速监测方法,形象地展示了石膏试件裂纹扩展时的声波波速动态演化过程。本文为基于声发射与波速监测技术的岩体受压破坏规律研究提供了一次有意义的探索。

关键词: acoustic emission, prefabricated crack, wave velocity, plane location, spectrum analysis, uniaxial compression

Abstract: To examine the failure characteristics and internal damage mechanism of the natural rock mass with cracks, this study conducts uniaxial compression tests on the specimens of gypsum material with the prefabricated cracks of oblique angles of 0?, 30?, 45?, 60? and 90? and with no pre-crack. Acoustic emission (AE) technology is used to measure sound signals and monitor full failure process and changes in sound waves. Spectral analysis of AE signals shows that the dominant frequencies detected during the specimen failure is lower than 500 kHz, while the noise is dominated by frequencies higher than this threshold. Hence, the noise can be removed reliably. An AE parameter, namely hits per second (HPS), is used to evaluate AE intensity. The failure modes of the specimens are divided into three categories: crushing (0?), compression-shear (30?, 45? and 60?), and splitting (90? and no pre-crack). Multiple regression analysis is used to improve the AE time-difference-of-arrivals (TDOA) location algorithm, achieving satisfactory results in locating internal failure points.

Key words: acoustic emission, prefabricated crack, wave velocity, plane location, spectrum analysis, uniaxial compression

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