Investigation in Effect of Flaw Angle and Length on Mechanical Behavior of Composite Samples Under Uniaxial Compression

In the uniaxial compression test of flawed rock samples, the samples are usually composed of a single type of rock, and research on flawed composite rock samples is limited. In order to explore the influence of flaw geometry on the mechanical behavior of composite rock mass, two kinds of rock‐like materials, A and B, with large differences in mechanical properties, were selected. The composite rock‐like samples with different flaw angles and lengths were prepared, uniaxial compression test and numerical simulation were conducted, and their strength, cracking and stress field distribution characteristics were analyzed. The results show that (1) the geometry of flaws has an influence on the strength and failure mode of composite samples, but the influence of flaw angle is greater than that of flaw length. (2) The difference in mechanical properties of materials on both sides of the composite sample leads to the development of cracks on side A earlier than those on side B. As the flaw angle increases, the position of crack expansion and aggregation gradually moves back, and the crack initiation is more difficult. (3) Flaws cause stress concentration, which is higher on side A due to differences in mechanical properties. As a result, cracks propagate earlier on side A than on side B. With increasing flaw angle, stress concentration at peak load decreases, delaying crack initiation and enhancing strength.