单轴加载作用下花岗闪长斑岩声发射特性与破坏前兆研究

Acoustic emission characteristics and failure precursors of granodiorite porphyry under uniaxial loading

准确判别岩石产生的失稳破坏是当前研究的热点。本文通过花岗闪长斑岩试样单轴加载声发射试验,分析其受载作用下失稳破坏全过程声发射的幅值、振铃计数率和b值变化特征。由试验结果可知:振铃计数率与b值的整体变化趋势具有高度相似性,均能反映岩石承载作用下其内部新裂缝的产生、发育、贯穿直至失稳破坏的变化规律。进一步发现,当加载应力达到其峰值强度的80%~90%时,不仅振铃计数率进入大幅度反复振荡的非稳定期,且声发射b值的峰值后“断崖式”回落中出现“波动中值”,此现象可作为岩石失稳破坏前的判据。研究成果可为岩体变形破坏预测预警提供理论依据。

It is a hot spot to distinguish the instability failure of rock accurately.Based on the uniaxial loading acoustic emission test of granodiorite porphyry samples,the variation characteristics of acoustic emission amplitude,ringing count rate and b value in the whole process of instability failure under load are analyzed in this paper.It can be seen from the test results that the overall change trend of ringing count rate and b value is highly similar,which can reflect the change law of the generation,development,penetration and instability failure of new cracks in the rock under the bearing action.It is further found that when the loading stress reaches 80%-90%of its peak strength,not only the ringing count rate enters the unstable period of large-scale repeated oscillation,but also the“fluctuation median”appears in the“cliff type”decline after the peak of acoustic emission b value,which can be used as a criterion before rock instability failure.The research results can provide a theoretical basis for the prediction and early warning of rock mass deformation and failure.