Microwave-assisted breakage of basalt: A viewpoint on analyzing the thermal and mechanical behavior of rock

Microwave-assisted breakage of rock has gained widespread popularity in the field of mining and geotechnical engineering. However, the breakage mechanism of rock is not clearly explained due to the involvement of complex multiphysics coupling issues. To study the thermal and mechanical behavior of basalt rock under the microwave irradiation, a coupled electromagnetic-thermal-mechanical mathematical model was established to analyze the heating process and explain the breakage mechanism. The results showed that in the energy conversion stage of the electric field, an inhomogeneous electric field distribution was observed in the cavity and basalt rock, which further resulted in the generation of a temperature gradient in the sample due to the dielectric losses of rock. This phenomenon can be demonstrated in the coupled electromagnetic-thermal model. The simulation results indicated that internal compression and external tension are the main causes of the fracture or blast of basalt rock. The experimental failure position of basalt was in line with the generation of the maximum thermal stress and strain in the simulation. The experimental and simulated results demonstrated synergistic stress and strain damage in the breakage process. The outcomes of this study can provide some scientific guidelines for the application of microwave-assisted breakage of rock. •Microwave heating progress for basalt was visualized and quantitatively studied.•Microwave-induced thermal energy in basalt is verified by simulation and experiments.•Heterogeneous thermal distribution led to the generation of thermal stress within basalt.•Stress distribution in basalt was internally compressed and externally tensioned.•Synergistic stress and strain damage was proposed to explain basalt breakage.