Uniaxial Compression Study on Mechanical Properties of Artificial Rock Specimens with Cross-Flaws

Uniaxial compression tests have been performed on artificial rock specimens weaken by feathered with cross-flaws. The effects of the angle alpha between the primary joint plane and the loading direction, the angle beta between the primary joint plane and the secondary joint plane, the length of the primary joint plane, the length of the secondary joint plane, and the number of secondary joint planes on the mechanical behaviors of artificial rock specimens have been studied. Research results show: (1) For artificial rock specimens with two intersecting joint planes of equal length, the uniaxial compressive strength (UCS) is generally higher when the primary and the secondary joint planes are more symmetrically distributed on both sides of the loading direction. This is mainly due to a shear failure being less likely to occur in this configuration. When the angle beta between the primary joint plane and the secondary joint plane remains constant, the UCS of specimens is lowest when the primary joint plane is perpendicular to the loading direction. (2) When the model specimen contains two joint planes and the angle alpha is the same, the change of the UCS with angle beta from 0 degrees to 90 degrees is the same for artificial rock specimens with different lengths of the secondary joint plane. When the angle alpha and the angle beta both remain unchanged, the UCS of the artificial rock specimen decreases with increasing length of the secondary joint plane. (3) When the model specimen contains varied (or equal) lengths of joint planes, the UCS of the specimen decreases with increasing number of secondary joint planes. The UCS does not change substantially when the number of secondary joint planes exceeds 4.