Abstract Rockburst tests on specimens of large-diameter using the device developed were carried out under different loading and unloading conditions. The weight distribution and the fractal characteristics of rock fragments after rockburst,and the relationship between the rockburst intensity and the fractal characteristics were studied. The fragments from specimens of large-diameter after each test were found to have different shapes and quantities. The fragments from specimens of large-diameter have fractal characteristics. The fractal dimension of fragments from the unloading tests of low confining pressure is larger than that of high confining pressure. Accordingly,the dissipation energy required is comparatively smaller and the intensity of rockburst produced is relatively smaller. The range of rockburst decreases as the increasing of the loading rate if the confining pressure is the same. The number of fragments of large size is small if the vertical loading is small,while the fractal dimension is larger.
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Received: 20 July 2013
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