Experimental Research On The Dynamic Mechanical Properties And Breakage Behavior Of Basalt Caused By Microwave Irradiation

Hard rock breaking is an essential process in rock excavation and mineral mining.The rock fragmentation method of "Microwave plus Machine" can improve the driving efficiency of machinery in hard rock and reduce the wear degree of the tool,making rock breaking process become more secure and efficient efficiently.Rocks are broken under all kinds of dynamic loads in the practical construction,therefore,it is necessary to carry out some research on the change laws of dynamic mechanical properties and fracture properties of rocks after microwave irradiation,the method could be applied to the actual rock breaking work much better.In this paper,the microwave launcher and split Hopkinson bar were used,studying the dynamic mechanical properties of basalt after microwave irradiation by changing a variety of factors such as microwave power and impact pressure,etc.The author analyzes the change law of crushing characteristics of basalt after microwave irradiation through collection of basalt fragments for particle sieving.The main research contents and results are as follows:(1)By combining the heating characteristics of the rock different minerals which is heated by microwave heating,we can analysis the basic principles of rock thermal fracturing and the reason for the variation of impact resistance of rock after microwave irradiation.It is concluded that microwave irradiation parameters,rock mass structure types,rock and mineral composition and particle size affect the strength of rock after microwave irradiation.(2)In order to ensure that the basalt samples did not burst apart during microwave irradiation,the basic physical and mechanical properties experiments of basalt specimens after 6 different power levels(OW?500W?700W?900W?1300W and 2000W)were studied,combined with XRD and SEM tests,the result showed that the pyroxene is a mineral which plays a major role in rock damage,the micro-cracks generated inside the basalt after microwave irradiation are mainly intergranular and transgranular.(3)The dynamic uniaxial compression experiments of basalt rocked by 500W?700W?900W?1300W and 2000W power microwave irradiation under three impact pressures of 0.2MPa?0.3MPa and 0?4MPa,it was found that peak of stress of basalt showed a descending trend with the change of the power.(4)Collecting and sieving basalt fragment after impact tests,the average size of the crushed rock is also increased in case of irradiation power.According to the fractal theory,it can be concluded that the fractal dimension D(fragmentation degree of rock)of the fragmentation distribution of basalt decreases with increasing irradiation power,and the two are linearly related.The larger the microwave power is,the smaller the fractal dimension becomes,and the rock sample gradually becomes smaller.It is plastically destroyed and can reduce the occurrence of rock burst to some extent.(5)By analyzing different rock-forming minerals present response and the influence of chemical composition on microwave-absorbing induced by microwave treatment,coming to that rocks have stronger ability when containing pyroxene or black mica minerals,and meanwhile,the more iron element in minerals,the higher temperature elevated amount under the microwave radiation.This research can forge close links between the method of microwave assisted mechanical rock breaking and practice,it provides a reference for the selection of the suitable strata and the selection of irradiation parameters for engineering.