Formation And Development Of Cracks In Magnetite Quartzite Under Microwave Irradiation

In view of the law of crack formation in rocks after microwave radiation,magnetite quartzite is selected as the research object,and the method of combining physical experiment and numerical simulation is adopted to control microwave power,irradiation time,different mineral components and other factors to develop magnetite quartzite under microwave action Experimental study on damage evolution;controlling microwave irradiation parameters,size and shape of mineral particles,content of absorbing minerals,distribution of mineral particles,and bedding structure planes,etc.,and systematically systemize the generation and development of cracks in magnetite quartzite under microwave action the study.The main research contents and results are as follows:1)From the theoretical level,analyze the principle of rock thermal fracture under microwave action.It is concluded that the microwave absorbing ability and thermal expansion characteristics of different mineral components in the rock are quite different.The absorbing minerals heat up rapidly after the action of microwaves,and produce a larger temperature gradient with weak absorbing minerals,and thermal stress is generated and the rock is different.Degree of thermal cracking.2)Controlling different microwave irradiation parameters to conduct microwave irradiation tests on magnetite quartzite with different mineral components,and conduct strength damage analysis and observation and analysis of microscopic cracks.The greater the microwave power and the longer the irradiation time,the more abundant the cracks develop and the weaker strength.The more significant it is;under a certain microwave power,there is an optimal irradiation time that not only damages the magnetite quartzite to a greater extent,but also maximizes the energy utilization rate;different mineral components have different effects on the microwave irradiation effect,and there is a dielectric inside.The higher the content of strong minerals,the more abundant the cracks will develop after microwave irradiation.3)Using PFC2 D numerical simulation software to analyze and study the generation and development of cracks in magnetite quartzite under microwave action.On the bas is of verifying the influence of microwave parameters and the content of absorbing minerals on crack development,it is obtained that the development of cracks first occurs at the junction of absorbing minerals and the matrix,and then radially expands int o the matrix along the mineral boundary,forming a network that envelops the absorbing minerals Cracks: Cracks are easy to appear at the tips of mineral crystals,which are caused by stress concentration caused by the singularity of thermal stress at the tips;under the same energy input,the larger the size of mineral particles,the faster the generation and development of surrounding cracks;The more dispersed the distribution of wave minerals,the greater the impact of microwave power,which will produce the same degree of rock damage,and the more microwave energy is required;By choosing different microwave radiation conditions,selective damage can occur between different oxide minerals(silicon oxide and iron oxide)in magnetite quartzite.Figure 78;Table 23;Reference 88...