Comparative Study on Heating Damage Characteristics and Drilling Effect of Sandstone in Deep Well under Microwave Radiation
In order to study the heating damage characteristics and drilling effect of deep-well sandstone radiated by mi-crowave radiation,deep-well sandstone with-940 m return air assisted Shimen coring from Hengyuan coal industry is used as the research object to analyze the changes of temperature,mass,longitudinal wave velocity of deep-well sandstone under the same input energy microwave radiation,and the average speed and torque of mechanical drill after drilling experiment with dif-ferent path processing.The results show that the mass change and the maximum surface temperature of the test specimen after microwave irradiation with high power for a short time(1.4 kW,214 s)is greater than that after microwave irradiation with low power for a long time(1.0 kW,300 s),and the wave velocity difference and damage factor increase with the increase of the surface temperature of the test specimen.The longitudinal wave velocity at 5 marked points was measured before and after mi-crowave irradiation,and it was found that the large difference of wave velocity and damage factor were mainly concentrated in the place with the highest temperature rise on the specimen surface.The drilling experiment results were analyzed under the conditions of comparison with or without limited deformation.Group A had no microwave radiation and limited deformation(path 1),group B had microwave power of 1.0 kW and microwave radiation time of 300 s,Group C had microwave power of 1.0 kW and microwave radiation time of 300 s,and Group B had limited deformation(path 2)and microwave power of 1.0 kW and microwave radiation time of 300 s.No limited deformation(path 3),group D microwave power is 1.4 kW,microwave radiation time is 214 s,there are four path processing methods limited deformation(path 4),the drilling effect from the best to the worst path is as follows:Path 3>Path 4>Path 2>Path 1,the analysis shows that under the same input energy with limited deformation condition,the drilling efficiency under 1.4 kW microwave radiation is about 1.3 times that under 1.0 kW micro-wave radiation,and under limited deformation condition,The efficiency of the microwave-assisted drilling method is about 8.5 times that of the conventional method without microwave radiation,that is,it is difficult to drill under limited deformation condi-tions.The research results provide a reference for the optimization of damage path and rock breaking with low energy consump-tion and high efficiency.
microwave radiationdeep well sandstonelateral compression limited deformationdrilling effectpath opti-mization
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