Influence of Prefabricated Fissure Combinations on Strength and Failure Characteristics of Rock-Like Specimens under Uniaxial Compression

Abstract Owing to the uncertainty in the rock formation process, there are different forms of fissure combinations that significantly influence the stability of engineering. In this paper, the peak strength and failure characteristics of rock-like materials with four types of double prefabricated fissure combinations was investigated by combining similar material tests of the digital image correlation (DIC) techniques and discrete-element numerical method (PFC2D). With reference to the experimental observation of crack initiation and propagation, the prefabricated fissure combination effect was analyzed by varying the fissure angle and its combination type. The results indicated that the mechanical properties of the specimen with prefabricated fissures were affected by the fissure inclination angle. When the double fissure inclination angles were 45°, the total fracture length was longest and the peak strength and the proportion of dissipated energy were smallest. It can be obtained that when the fissure inclination angle reached 45°, the effect of the prefabricated fissure combination was maximum. Except for the specimens whose fissure inclination angles had 90° cracks that processed along a perpendicular direction, the cracks of other types propagated and coalesced near the lower side of the middle specimen. The research can provide guidance for controlling engineering disasters involving complex fissure combinations under natural geological conditions.