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Abstract The laboratory tests are made for studying characteristics of acoustic emission(AE) of granite from Linyi in Shandong province at 20℃ to 800℃ using hydraulic-pressure servo testing system MTS810 and acoustic emission instrument AE21C. The relationship between ringdown count rate of granite and time as well as the relationship between AE parameters and stress-strain curves due to uniaxial compression loading are analyzed under different temperatures. Studies have shown that ringdown count rate rises and AE activity becomes more frequent with temperature increases both in the processes of heating and loading. AE parameters are quite different at and after the high temperature，of which AE parameters after high temperature are significantly lower than that at high temperature；and internal cracks are fewer resulting in that mechanical properties at high temperature are superior to that after high temperature. Ringdown cumulative count of granite at high temperature is higher than that after high temperature；especially at 800 ℃ when there is more than a doubled difference. The high temperature causes a significant increase in energy and accelerating the energy dissipation. The granite specimens showed brittle failure such as splitting and shear failure which did not appear strong ductile failure. The strength of the rock decreases and macroscopic cracks increase due to energy dissipation and elastic energy release which eventually cause deformation and failure of granite.
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Received: 23 May 2012
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2013, Vol. 32 
