Visualization test and numerical simulations of 2D blasting crack propagation

Drilling and blasting, characterized by their efficiency, ubiquity, and cost-effectiveness, have emerged as predominant techniques in rock excavation; however, they are accompanied by enormous destructive power. Accurately controlling the blasting energy and achieving the directional fracture of a rock mass have become common problems in the field. A two-dimensional blasting (2D blasting) technique was proposed that utilizes the characteristic that the tensile strength of a rock mass is significantly lower than its compressive strength. After blasting, only a 2D crack surface is generated along the predetermined direction, eliminating the damage to the reserved rock mass caused by conventional blasting. However, the interior of a natural rock mass is a "black box”, and the process of crack propagation is difficult to capture, resulting in an unclear 2D blasting mechanism. To this end, a single-hole polymethyl methacrylate (PMMA) test piece was used to conduct a 2D blasting experiment with the help of a high-speed camera to capture the dynamic crack propagation process and the digital image correlation (DIC) method to analyze the evolution law of surface strain on the test piece. On this basis, a three-dimensional (3D) finite element model was established based on the progressive failure theory to simulate the stress, strain, damage, and displacement evolution process of the model under 2D blasting. The simulation results were consistent with the experimental results. The research results reveal the 2D blasting mechanism and provide theoretical support for the application of 2D blasting technology in the field of rock excavation.