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

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.