Variation Characteristics of Pore Structure and Energy Evolution Law of Marble Under Microwave Irradiation
In order to study the pore structure change and strength deterioration characteristics of marble under different microwave irradiation power and time,the pore structure evolution characteristics of marble under different microwave power and time were analyzed based on nuclear magnetic resonance technology.With the increase of microwave irradiation power or microwave radiation time,the quality,hardness,wave velocity,peak strength and elastic modulus of marble all show different degrees of decline,and the porosity of the rock increases,and the degree of fragmentation is obvious.They are verified by tests such as acoustic waves and rock mechanical strength.At the same time,the damage degradation model of microwave radiation was established based on NMR,and the damage model had good effect.The damage model can further reflect the damage degree of three kinds of damage variables such as porosity under microwave radiation,and can provide reference for the study of damage and deterioration of similar rocks.In addition,the energy evolution process of marble was analyzed based on the energy dissipation theory.With the increase of microwave power or irradiation time,the release amount of elastic energy becomes less and less,and the elastic deformation changes to plastic deformation.With the increase of microwave radiation time from 60 s to 300 s,the total energy and elastic energy both show a linear downward trend,while the dissipated energy showes a linear upward trend,that is the total energy decreased from 350.93 kJ/m3 to 299.07 kJ/m3,with a decrease of 14.78%.The elastic energy decreases from 311.68 kJ/m3 to 240.49 kJ/m3,with a decrease of 22.84%.The dissipated energy increases from 39.25 kJ/m3 to 58.58 kJ/m3,with an increase of 49.25%.When the microwave irradiation power increased from 1 kW to 3 kW,the total energy and elastic energy also show a linear decline trend,and the dissipative energy showes a linear increase trend,that is the total energy decreases from 334.58 kJ/m3 to 289.70 kJ/m3,with a decrease of 13.41%.The elastic energy decreases from 287.39 kJ/m3 to 223.07 kJ/m3,with a decrease of 22.38%.The dissipated energy increases from 47.19 kJ/m3 to 66.70 kJ/m3,with an increase of 41.34%.The results show that the quality,hardness,wave velocity,peak strength and elastic modulus of marble decrease and the porosity increases with the increase of microwave irradiation power and time.With the increase of microwave irradiation power and time,the internal energy of the sample is converted,the proportion of dissipative energy is increased,and the proportion of elastic energy is decreased.The research results reveal the changes of pore structure and energy evolution of marble under microwave irradiation,which also has certain reference significance for the damage evolution mechanism of other types of rock.
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