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Abstract In view of characteristics of static and dynamic uniaxial compression，such as mining rock pillar，the influence of initial mesoscopic damage level under uniaxial static compression on mechanical properties of rock specimen with a single fissure under subsequent uniaxial dynamic compression and the energy dissipation mechanism are simulated by particle flow code. Minor influence of initial damage level under static uniaxial compression on patterns of stress-strain curves of rock specimens which are under dynamic uniaxial compression subsequently is observed. The damage at pre-peak and the crack coalescence at post-peak for damaged rock specimens behave in obvious progressions and jumps. Lower strength of specimens is presented with the increase of initial damage. But the subsequent dynamic compression suggests the strength increases drastically compared with one due to initial damage. The normal and tangential fracture stresses of crack tip are reduced slightly with the increase of initial damage. And the normal fracture stress is reduced but the tangential stress increases sharply with the increase of fissure dip angle. The final macroscopic fracture mode of specimens under subsequent dynamic compression does not change around initial damage level. However，more microcracks and stronger damage localization are observed with the increase of initial damage. The energy dissipation is closely related to the mesoscopic damage evolution of rock mass. The stronger the initial damage of rock mass is，the less energy is absorbed to reach the peak failure，but more energy is dissipated at post-peak. The more dissipation energy and stored elastic strain energy at peak strength are，the stronger damage fracture at post-peak is with the increase of fissure dip angle.
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Received: 12 December 2012
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2013, Vol. 32 
