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Abstract Through the load test of rock，different rocks are tested and the mechanical and acoustic emission(AE) characteristics of rocks are studied. Stress-strain curves，AE accumulative total number and AE rate of rock failure are gotten. And AE features including the relationships between AE and time，AE and stress are studied. This study discusses emphatically the AE quiet period of the loading processes to those rocks whose plastic deformation is obvious. In this AE quiet period，the stress increment will be diminished in unit time when stress approaches to peak value strength and it will need more time. Moreover，AE rate will be declined and AE quiet period will also appear in this stage. But for those rocks whose plastic deformation is not obvious，this AE quiet period will not appear. In addition，by fractal theory，the AE values of different stress rates especially at quiet period are calculated and analyzed. It is found that the fractal values are lower in initial loading stages and increase gradually along with stress，about at the 40% of stress rate，fractal values begin to fall down. The fractal values go down to the minimum near the peak value stress and foreshow rock failure. Furthermore，combined with indoor experiment，some problems of in-situ monitoring and prediction are discussed，It gives the theoretical basis and methods for in-situ rock mass monitoring and forecast by AE technology.
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Received: 17 October 2008
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