Experimental Research On Damage Characteristics Of Basalt By Microwave Cyclic Irradiation

Microwave thermal effect can effectively induce micro-cracks in rocks and cause thermal fracture of rocks.Studying the damage characteristics of microwave on rocks has important practical significance for promoting the development and application of microwave-assisted rock breaking technology.Therefore,the damage characteristics of basalt by microwave cyclic irradiation were tested to preliminarily explore the effects of damage and destruction of rock caused by microwave cyclic irradiation.Firstly,the cyclic irradiation experiment and continuous irradiation experiment with different microwave irradiation parameters has been carried out,and then the splitting tensile strength were tested.Finally,the damage characteristics of the basalt by microwave cyclic irradiation were analyzed.The main research contents and conclusions are as follows(1)The fundamental role of dielectric polarization in microwave heating dielectric materials was pointed out,the principle and characteristics of microwave heating were summarized.It is analyzed that the inconsistent deformation caused by the differential volume expansion of various media in rocks under objective constraints is the fracture mechanism of rocks under the thermal-mechanical coupling effect caused by microwave irradiation(2)The changes of longitudinal wave velocity,surface temperature and appearance of the basalt specimens before and after microwave irradiation under various parameters were recorded and compared respectively.The energy conversion relationship in the process of microwave irradiation was derived,and the corresponding microwave energy conversion rate under each parameter was calculated.The results show that,the microwave energy conversion rate decreases with the increase of microwave power and irradiation time,while the microwave energy conversion rate increases significantly with the increase of the cyclic number at a constant microwave power and irradiation time(3)The degree of damage weakening of basalt caused by microwave irradiation was measured by the quantitative calculation indexes such as tensile strength,fracture toughness.