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Abstract Based on the independent development of meso-shear test equipment for coal rock and PCI–2 acoustic emission detection analysis system，acoustic emission features of sandstone with different saturation degrees of 0%，50% and 100% during shearing process are studied；and the relationship between evolution law of acoustic emission signal and cracking and extension of sandstone is discussed. The results show that acoustic emission activity is associated with the whole shearing process of sandstone. The acoustic emission activity is not obvious and acoustic emission signal is comparatively small before the shear stress peak value，but after it the acoustic emission signal leaps. With the increase of water content，the shear strength reduces，and the leap point of acoustic emission signal appears in advance successively. Under different moisture states，the peak value of acoustic emission events rate always appears lag the time that the shear stress reaches its peak. With the saturation degree of 0%，the surface crack of sandstone appears after the shear stress peak and the acoustic emission activity is the most intense；the cumulative acoustic emission events at failure is the most，that is，the cumulative damage is the biggest. But with the saturation degrees of 50% and 100% the surface crack of sandstone appears before the shear stress peak，the cumulative acoustic emission events at failure is comparatively less，and the cumulative damage is smaller.
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Received: 21 November 2011
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2012, Vol. 31 
