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Abstract Acoustic emission(AE) technique was employed to measure the AE signals of coarse-grained granite and fine-grained sandstone with prefabricated square holes or circular holes under uniaxial compression test. AE time-space evolution characteristics during failure process were studied based on simplex locating algorithm. AE activities characteristics，AE energy release rate and spatial correlation length were also analyzed. The results show that the three-dimensional location of AE events directly reflects the process of initiation，propagation and evolution of microcracks and the stress redistribution within the specimens. For specimens that the distance of prefabricated holes is same with the prefabricated hole size，located AE event are clustered in the central of specimens；and shear failure occurs in the center area of specimens. The AE activities of granite with coarse and heterogeneous grains isn?t much stronger during the whole loading phase；while the AE activates of sandstone with thin and homogeneous grains isn?t enhanced until the later period of loading. Before the failure of rock，microcracks coalescence into large scale cracks，which result in AE activates weaken and AE energy release rate increases；during this phase，many AE signals are superimposing，which induces the AE quiet period and blank area of located AE events occurred. During rock fracture process，long-range correlations are established by redistribution of stress field，which cause the spatial correlation length obviously increasing before rock failure and reach its maximum value when rock failure.
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Received: 07 May 2012
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2012, Vol. 31 
