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Effects of cyclic loading and unloading rates on acoustic emission evolution and felicity effect of unstable rock mass

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Document pages: 16 pages

Abstract: Uniaxial cyclic loading and unloading compression tests with six loading rates and six unloading rates were carried out on a combined test-bed. The effects of loading rate and unloading rate on rock acoustic emission characteristics are revealed. The results show that increasing the loading and unloading rate will reduce the total acoustic emission ring in the whole process of rock deformation and failure. In the same cycle, increasing the loading rate will reduce the acoustic emission ring in the loading stage, and increasing the unloading rate will reduce the acoustic emission ring in the unloading stage. The total AE count was negatively linear with loading and unloading rates. The loading stage is the active stage of acoustic emission, and the influence of loading rate on acoustic emission characteristics is more obvious. Especially when loaing rate was greater than 2.0 kN s, brittle failure of rock specimens became noticeable. After the cyclic load reached the uniaxial compressive strength of 1 3∼1 2 times, the rock Felicity effect became more obvious. With the increase of the loading rate, the Felicity ratio decreased in the elastic stage and increased a little in the plastic stage, whereas with the increase of the unloading rate, the Felicity ratio decreased gradually in the elastic stage and remained almost the same in the plastic stage.

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