Study on Characteristics of Directional Expansion Cracking Behavior of Rock-Like Material with a Non-Circular Hole

The dilatancy test of concrete samples with non-circular holes was carried out by using a self-designed splitter. The failure load characteristics, crack propagation law and stress distribution around the holes of specimens with different hole shapes were studied. The results show that: compared with the circular hole specimens, the peak load of the elliptical hole, rectangular hole and diamond hole specimens is significantly reduced, and the load reduction ratio is 28.2% ~ 70.3%. Elliptic, rectangular and rhomboid holes all have a guiding effect on the crack initiation. The guiding effect of elliptic and rhomboid holes on the crack initiation increases with the increase of the ratio of the long and short axes (diagonal lines), while the guiding effect of rectangular holes does not change significantly with the change of the ratio of the side length. In terms of crack guiding effect, rhomboid holes are better than elliptic holes, and elliptic holes are better than rectangular holes. The change in the shape of the cavity produces the obvious tensile stress concentration phenomenon, and the degree of tensile stress concentration at the long axis of the elliptical cavity increases with the increase of the ratio of the short axis to the long axis. The degree of tensile stress concentration at the four tips of the rectangular hole decreases first and then increases with the increase of the ratio of side length. The tensile stress concentration of rhombic hole increases first and then decreases with the increase of diagonal ratio.