Failure Mechanical Characteristics of Rock with Different Hole Shapes

Due to the role of geological structure, the underground rock contains a large number of holes. In order to study the influence of the hole on the mechanical characteristics of the rock failure, the numerical simulation analysis of the intact rock and the rock with three shapes holes(circle, square, triangle) are carried out by using PFC2D. The results show that the rock strength varies with the shape of the hole. Circular holes have the least impact on strength and triangles have the greatest impact. At the same time, different holes shapes have different failure morphology, the intact rock sample forms a penetrating fracture zone inclined by 60°. For the circular hole, forms a through-fracture zone along the upper left and lower right corners. The square hole sample forms an "X"-shaped fracture zone along the four corners. For the triangular holes sample, the damage occurs first at the two positions of the left and right foot of the hole, and then the fracture zone is formed along the upper right corner and the two feet of the sample. Finally, theoretical analysis of stress distribution characteristics around the rock with circular holes is carried out. The compressive stress concentration occurs on the left and right sides of the circular hole, the tensile stress concentration occurs at the top and bottom boundary of the hole. And the tensile crack occurs at the top and bottom of the hole, tensile and shear mixed cracks appear on the left and right sides of the hole from numerical simulation. The crack distribution of numerical simulation is consistent with the theoretical stress analysis results.