Effect of Irradiation Spacing on Fracturing of Hard Rocks Using an Open-Ended Microwave Antenna

Microwave-assisted mechanical breakage of hard rocks is a promising alternative to drill and blast, especially in areas with stringent environmental protection regulations. Past research focused on numerical and laboratory studies on the change in the physical and mechanical properties of rocks, primarily using multi-mode microwave cavities. For the research using open-ended microwave applicators in fracturing large pieces of rocks, the 3D damage zone of one irradiation can be characterized. However, those research falls short in examining the interaction between different irradiations, i.e. how does the distance between two irradiations affect the interaction between the fractures? Using a customized open-ended microwave antenna and large rock blocks, this paper experimentally investigates the fracture interactions between two irradiations when different irradiation spacings are adopted. From the test results, the optimal irradiation spacing is determined. The finding of the paper provides a fundamental basis for the design of the irradiation pattern when the technique is commercially used in the field.