Abstract: Particle flow code was used to simulate uniaxial compression test of rock containing one closed central pre-existing fissure. The effects of fissure width, fissure length, friction coefficient and dip angle on the failure characteristics of cracked rock were analyzed. Results show that crack closure has impact on the strength and failure characteristics of cracked rocks. With the decrease of fissure length or increase of fissure's friction coefficient or the decrease of dip angle to zero or the increase of dip angle to 90°, the failure characteristic of cracked rock is more similar to that of intact rock. Extension of wing cracks and secondary cracks forms the macroscopic failure plane of rock. Mode-I fracture extension of wing cracks forms the macroscopic failure plane of rock while mode Ⅱ-Ⅰ fracture extension of secondary cracks forms the macroscopic failure plane of rock.

Key words: cracked rock, failure characteristics, closed fissure, uniaxial compression, particle flow, fracture mechanics