Acoustic emission real-time monitoring and analysis of microwave thermal damage of granite

• Published in: Environmental earth sciences Vol. 83; no. 15; p. 443
• Main Authors: Gu, Chao, Sun, Qiang, Geng, Jishi, Zhang, Yuliang, Jia, Hailiang
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2024; Springer Nature B.V
• Subjects: Acoustic emission; Acoustic propagation; Acoustics; Biogeosciences; Conduction; Conduction heating; Crack propagation; Damage; Earth and Environmental Science; Earth Sciences; Emission analysis; Energy conservation; Environmental Science and Engineering; Evolution; Failure mechanisms; Fracturing; Geochemistry; Geology; Granite; Heating; Hydrology/Water Resources; Irradiation; Microwave heating; Microwave radiation; Monitoring; Original Article; Radiation damage; Real time; Resource development; Rock; Rocks; Sediment samples; Terrestrial Pollution; Microwave; Real-time acoustic emission; Thermal damage; Granite
• ISSN: 1866-6280; 1866-6299
• DOI: 10.1007/s12665-024-11745-5

Microwave rock fracturing has a wide range of application prospect in deep resource development due to its advantages of high efficiency and energy saving, and the study of damage in the fracturing process is of great importance in guiding the safety and high efficiency of rock fracturing. However, damage characterisation during microwave rock fracturing has not been sufficiently investigated. Therefore, studying the characteristics of crack propagation and evolution during microwave heating is of great significance. This paper investigates the crack evolution characteristics and failure mechanism of granite under microwave irradiation by collecting the real-time acoustic emission signals during heating using the self-developed microwave hot rock damage real-time dynamic monitoring system. The results indicate similar change characteristics of the real-time acoustic emission counts, energy, and RA/AF values of rock samples with corresponding stages after 900 s of microwave power irradiation at 0.3 kW, 0.6 kW, and 0.9 kW under the same temperature range and the most active acoustic emission range is 200–310 °C. The degree of thermal damage to rock samples and the power show a positive correlation under similar temperature ranges. The characteristics of real-time RA/AF values reflect the tensile failure of granite during microwave heating, accounting for more than 65%. However, the shear crack ratio increases with irradiation time or power, with the highest ratio of 33.3%. In addition, the real-time acoustic emission curve in the microwave heating process reaches the acoustic emission active point at 200 °C, which is far less than 300 °C and 350 °C of the traditional conduction heating method, with 1/2th and 1/15th of the heating time of the traditional conduction heating method, indicating the superiority of microwave rock breaking.