In order to verify size effect on acoustic emission characteristics of rock under uniaxial compression, the acoustic emission experiments with 7 kinds of height specimens were carried out, including uniaxial compression, uniaxial cyclical compression and uniaxial increasing cyclical compression. The results show that rock's acoustic emission characteristics under uniaxial compression have three stages. At first, the velocity of acoustic emission decreases slowly with the increase of compressing force. Then the velocity of acoustic emission increases stably with the increase of compressing force. Last the velocity of acoustic emission increases sharply when the compressing force is close to rock's peak strength. Under uniaxial cyclical compression, rock's acoustic emission at each cyclical loading decreases slowly with the increase of cyclical time. The uniaxial increasing cyclical compression shows that rock's acoustic emission increases greatly when the load surpasses the previous load and the acoustic emission increases very slightly when the load is less than the previous load. Generally, the influence of size effect on rock's acoustic emission is obvious. However, it is greatly affected by many factors and difficult to guarantee quantity accuracy of acoustic emission.
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