关键词: 微波辅助破岩, 温度特性, 电场强度, COMSOL, 破碎特性

Abstract: To explore the rock heating and fracturing mechanism in microwaveassisted rock breaking, five groups of microwave irradiation tests are conducted on basalt samples under various microwave power and irradiation times, which provide the temperature distribution and fragmentation state of rock surface. For deducing the rockbreaking mechanism, the COMSOL multiphysical fieldmodeling software is used to simulate the distribution of electric and temperature fields inside the rock. Test results show that the increase in the microwaveemission power and irradiation time increase the rocksurface temperature, breaking area, breakingpoint depth, crack quantity, and crack length. Furthermore, simulation results reveal the following: (1) The electricfield intensity in rock decreases sharply when the microwave is transmitted from the microwave antenna to the upper rock surface and exhibits an inverted cone distribution. (2) Additionally, the rockfragmentation damage under microwave irradiation is revealed to be mainly attributed to the electricfield intensity. The electricfield power results in an uneven distribution of energy density in different rock parts, causing a change in the temperature gradient and foreign thermal expansion, which lead to fragmentation damage. The evolution of rockfragmentation damage can be divided into three stages. Based on the regression analysis of mathematical models for the heating process of rock samples, the microwaveemission power has considerable influence on temperaturedependent characteristics. A microwave irradiation power of 26.645 kW is shown to cause fragmentation damage of rock in a short time, indicating the best irradiation effect.

Key words:  , microwaveassisted rock breaking, temperature characteristics, electricfield intensity, COMSOL, fracturing characteristics