Study on the Mechanical Destruction Characteristics and Crack Expansion of Test Block Containing Cross Fissures

In nature, fissures in rock mass are often distributed in the shape of X and V. In order to explore the influences of cross fissures on the mechanical failure characteristics of rock mass and crack propagation under load, rock specimens with dip angles of 30°, 60° and 90°, fracture lengths of 10 mm, 20 mm, 30 mm and 40 mm and shape of V and X were producted, respectively. The RYL-600 computer-controlled rock shear rheometer was adopted to conduct uniaxial compression tests, and the mechanical properties, crack propagation and evolution law of rock-like specimens with different crack lengths and angles were analyzed. The results show that the stress intensity of the rock mass test block with X-type and V-type fissures is obviously lower than that of the complete test block, and the stress-strain curve of the rock mass test block with cross frac fissures tures is obviously earlier entering failure state than complete test block. The angle and length of fissures can change the initiation, propagation direction and failure mode of rock mass. With the increase of fissure angle, the crack propagation of the test block with cross fissures becomes more obvious, and the area and number of surface peeling off gradually decrease.