Research on the Fracture Properties and Mechanism of Carbon Dioxide Blasting Based on Rock-like Materials

Abstract

Liquid carbon dioxide blasting technology has a wide range of applications and is characterized by sound fracturing effects, low vibration hazards, and high safety. In order to investigate the characteristics and mechanism of CO2 phase change rock breaking, liquid CO2 blasting tests on rock-like specimens were carried out in this paper. The results show that 130 MPa is the threshold value at which a CO2 blasting system moves from dynamic tensile stress damage to dynamic pressure stress damage. When blasting pressures of 100 MPa and 70 MPa are used, the lumpiness ratio of the fragments does not change much as the strength of the rock changes, so a suitable blasting pressure should be chosen to improve the blasting effect. Under the impact of blast stress and high-pressure gas flow, cracks develop to form a rough failure surface.

Blasting Fragmentation Study Using 3D Image Analysis of a Hard Rock Mine

“…In the PortaMetrics particle size distribution curves, the values measured in the field were different for each blasting performed. Despite the small differences in each of the blasting designs, some deviations could be accounted for, such as the drilling operating conditions [8], explosive energy control [8][9][10], geomechanical characteristics of the rock massif [10], experimental errors of the image sampler, errors in the delineation of the rock limits and, consequently, of the size of the fragments, and errors of the FMAI algorithm.…”

“…The programmed release and control of explosive energy during blasting is performed by adjusting the departure angle at the detonation of the explosive charge. This angle is determined by the relationship between the burden and spacing; consequently, the explosive energy and the level of fragmentation of the rocks are controlled by adjusting these parameters [7,8]. Additionally, the hole diameter determines the mesh size (burden x spacing); therefore, for holes with smaller diameters, smaller spacings generate smaller fragment sizes than blasts with larger hole diameters and spacings.…”