Abstract
Results of investigation of the acoustic emission frequency spectra in sandstone, dolomite and marble samples under uniaxial incremental compressive load are presented. The measurements of AE peak hold spectra within each incremental loading cycle in frequency range from 100 Hz-100 kHz, and averaged over 30 s interval spectra in the range from 5 kHz to 100 kHz, were made. It was found that for nonhomogeneous rocks i.e. sandstone and dolomite the dominant frequency bands shifted towards higher frequencies with the increase of load. Prior to failure of these samples, the increase of low frequency components was observed. For the marble (carrare) which has more homogeneous structure the spectra were less differentiated and their evolution less pronounced. The results obtained support the hypothesis of stress concentration on limits of the defects in regions of eventual failure planes. The observed increase of low frequency components could be used in practice in the prediction of failure of heterogeneous rocks.References
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