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Abstract Experiments on granite under uniaxial compression at high temperatures of 25 ℃–850 ℃ and after high temperature 25 ℃–1 200 ℃ were conducted；and the fracture surfaces were observed by scanning electron microscope (SEM) to study the effect of temperature on rockburst proneness. The results show that：(1) Two critical temperatures are found when the rockburst proneness index of samples changes with temperature from 25 ℃ to 850 ℃. The first is from 150 ℃ to 250 ℃；and the second is between 500 ℃ and 600 ℃. The rockburst proneness index increases substantially from the room temperature to the first critical temperature，and it decreases little between the first and the second critical temperatures；above the second critical temperature，it decreases largely. (2) While the samples are refrigerated after high temperature，the rockburst proneness index decreases generally with the temperature increases. The rockburst proneness is strong from 25 ℃ to 200 ℃；it is moderate between 200 ℃ and 800 ℃；above 800℃，it becomes weak. (3) Effective impact energy index and residual energy index are reasonable while the other three indices are unsuitable for incomprehensive information. (4) Four typical stress-strain curves were analyzed to get the relation with the rockburst proneness，and the corresponding relation among the heating mode，the temperature stage and these curves. (5) Based on the macroscopic and microcosmic characteristics of failure samples，it is indicated that the failure mechanism in turn is tension failure，tension-shear failure and shear failure as the rockburst proneness lowers，and it has the tendency that transforms from brittle fracture mechanism at low temperature to ductile fracture mechanism at high temperature.
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Received: 11 January 2010
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