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Experimental Research on Mechanical Properties of Rocklike Specimens Containing Single Cracks of Different Inclination Angles under Uniaxial Compression

The effect of crack inclination angle on strength, failure mode, failure process, law of crack initiation and propagation is studied by uniaxial compression test on rocklike specimens with single pre-existing cracks of different inclination angles. It has been found that the stress-strain curve of the cracked specimen goes through five stages: compressive densification stage, stable linear elastic stage, crack extension stage, strain softening stage and residual strength stage, which is similar to the intact sample. The peak compressive strength of the cracked sample changes as a V-shaped curve with the increase of the crack inclination angle, and the minimum peak compressive strength is at the angle of 45° and the maximum compressive strength at angle 0° or 90°. The crack initiation angle decreases gradually with the increase of the crack inclination angle; on the contrary, the initiation speed and stable propagation speed of the crack increase with the crack inclination angle. The crack starts to expand with the increasing load gradually. The crack extension is stable and not obvious at first, when the load reaches a certain value, the crack expands quickly until the cracked specimen is broken completely.