Experimental Study on the Fracture Characteristics of Hole-Crack in Rock-like Material under Biaxial Compression

Abstract

Using experimental methods to study the influence of hole and cracks on the mechanical properties and fracture characteristics of rock-like mortar materials under biaxial compression conditions. The double crack specimens with hole depths from 0–100 mm are prefabricated to study the strength and deformation characteristics of the specimens under different lateral loads σ2 = 0–6 MPa. The evolution process of secondary crack initiation, development, and connection of the hole-crack specimens are recorded. The results show that: (1) One type of rock mortar test material is prepared, and its main physical and mechanical parameters are all within the range of sandstone, which can effectively simulate the stress deformation characteristics of sandstone. (2) When the depth of the holes in cracked samples exceeds 50% of the length, the strength and deformation of the samples undergo a sudden change. When the depth of the hole in the crack specimen increases from 40 mm to 60 mm, the peak stress decreases most significantly. Moreover, the maximum values of the strain value at peak strength and lateral strain both occur at a hole depth of 60 mm. (3) When the cracked specimen contains through-holes, the failure mode is composite fracture and shear composite fracture. When the depth of the hole is different, the fracture forms include tension composite fracture, shear composite fracture, and composite fracture.