Abstract: The essence of microwave-weakening rocks is thermal destruction. Accurately understanding the temperature distribution characteristics of rocks under microwave irradiation is of great importance for indicating the extent and degree of microwave weakening of rocks. In this paper, the numerical model was first calibrated through experiments, and then the temperature distribution characteristics of granite under microwave surface irradiation were studied using the calibrated numerical model. The influence of irradiation distance, tilt angle, and antenna type on the temperature distribution characteristics (surface maximum temperature rise, shape and size of the high-temperature zone and the influence zone) of rocks was also discussed. The research results show that the surface temperature rise of rocks is symmetrical around the center point and gradually decreases from the center to the edge, and the surface maximum temperature rise of rocks decreases with the increase of irradiation distance and rock tilt angle. The surface maximum temperature rise of microwave-treated rock using the converging waveguide antenna irradiation is 1.35 times that of the standard waveguide antenna, but it gradually decreases as the irradiation distance increases and ultimately lower than that of the standard waveguide antenna. The high-temperature zone on the rock surface is approximately circular when the irradiation distance and tilt angle are zero, and the shape of the high-temperature zone changes with the change of irradiation distance, tilt angle, and antenna type. The surface size and depth of the high-temperature zone are negatively correlated with the irradiation distance and tilt angle and the cross-sectional size of the high-temperature zone decreases gradually with depth until it disappears. Similarly, the surface influence zone of rocks is approximately circular when the irradiation distance and tilt angle are zero, and it also changes with the change of irradiation distance, tilt angle, and antenna type. The surface size of the influence zone is positively correlated with the irradiation distance and tilt angle, and the cross-sectional size of the influence zone initially increases and then decreases with increasing rock depth.

Key words: microwave facial treatment, temperature distribution characteristics, maximum temperature rise, high-temperature
zone, influence zone