The Acoustic Emission (AE) characteristics of rock materials are affected by lithology, strength and loading conditions. It is significant for us to do some researches on AE signal frequency characteristics under different loading conditions and different stages of fracturing in order to select proper AE sensors with corresponding resonant frequencies for maximum effect through receiving AE signals. During the experiment, we used doublefrequency and double-channel AE detector developed by ourselves to catch AE signals from rock samples loaded by uniaxial compression machine; and analyzed the frequency characteristics of AE signals at different stages of fracturing. For granite samples, the results showed that there was no obvious AE signals before the relative stress achieved 70% level. Between 85% and 100% relative stress level, there were quantities of AE signals, and the main frequencies concentrated in the bands of 150-180 kHz and 30-60 kHz. For packsand samples, there were several AE signals between 5% and 30% relative stress level. Between 60% and 100% relative stress levels, the AE signals were discrete. The dominant frequency concentrated between 60 kHz and 120 kHz.
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