Effect of dominant fractures on triaxial behavior of 3D-printed rock analogs with internal fracture networks

Internal structural defects in engineering rock masses vary in size, exhibit complex shapes, and are unevenly distributed. Dominant fractures within a rock mass often play a critical to its mechanical behavior, directly affecting the macromechanical properties and failure modes. These fractures affect the instability and failure of the surrounding rock, significantly impacting the overall stability of engineering structures. Herein, sand-powder three-dimensional (3D) printing technology was used to prepare rock-like specimens with internal fracture networks. Triaxial compression testing, post-failure fracture mapping, and fractal dimension analysis of the fracture surfaces were conducted to investigate the effects of dominant fracture angles on the strength and deformation of rocks with internal fracture networks under triaxial stress. The results indicate that the dominant fracture angle has a pronounced effect on the mechanical behavior of rock. With increasing angle, both compressive strength and elastic modulus exhibit an initial decline followed by an increase. Moreover, higher confining pressure significantly improves the compressive strength of fractured rock. This enhancement weakens as the confining pressure further increases. Moreover, with increasing confining pressure, the differences between the maximum and minimum values of elastic moduli and lateral strain ratios in fractured rock gradually decrease. Thus, the impact of the dominant fracture angle on rock mass deformation decreases with increasing confining pressure. This research elucidates the effects of dominant fracture angles on the mechanical and failure properties of complex fractured rock masses and the influence of the confining pressure on these relationships. It provides valuable theoretical insights and practical guidance for stability analyses in engineering rock masses.