Research On Electromagnetic Radiation And Microseismic Response Mechanism Of Rock Mass Fracture

In the process of coal mining,when the far-field strong microseismic is transmitted to the roadway,it will cause the fracture of the roadway surrounding rock.During the fracture process,electromagnetic radiation and microseismic signals will be generated.The emergence of mine rockburst is often accompanied by the generation of electromagnetic radiation.Exploring the mechanism of electromagnetic radiation and microseismic produced by rock fracture and the coupling response mechanism of electromagnetic radiation and microseismic has important research significance for preventing roadway rockburst disaster and locating the location of farfield strong earthquake.This paper studies the characteristics of microseismic and electromagnetic radiation produced by the compression and fracture process of sandstone under dynamic and static load,so as to provide a theoretical basis for the surrounding rock support of underground roadway.From the perspective of stress wave transmission and piezoelectric effect,the behavior of sandstone releasing electromagnetic radiation signal after loading is theoretically analyzed,and it is found that the electromagnetic radiation intensity produced by piezoelectric effect is related to time and increases with the increase of loading stress.At the same time,the intensity amplitude of the electric field will also decay with the increase of propagation distance,and its attenuation coefficient is related to the resistivity of rock mass.For rocks with high resistivity and poor conductivity,the electromagnetic radiation generated by piezoelectric charge can not be completely ignored.In order to study the electromagnetic radiation characteristics produced by sandstone fracture and reveal the coupling mechanism between electromagnetic radiation and microseismic,the relationship between electromagnetic radiation signal intensity and sandstone deformation characteristics under dynamic and static load is studied by impact test and uniaxial compression test;The deformation characteristics of sandstone specimen under uniaxial compression and the coupling relationship between electromagnetic radiation signal and microseismic signal are analyzed;At the same time,taking 22117 return air roadway of Shanxi Luning coal mine as the research background,according to the fracture process of near-field surrounding rock induced by dynamic and static combined load,the coupling mechanism of microseismic and electromagnetic radiation is analyzed,and the response characteristics of microseismic and electromagnetic radiation in roadway surrounding rock are obtained.The results show that under the condition of dynamic load failure:(1)The failure of sandstone takes on two forms: shear failure and tensile failure.The electromagnetic radiation generated by shear failure and tensile failure of sandstone specimen fluctuates accordingly according to the failure process of the specimen.The general performance is that a certain intensity of electromagnetic radiation is generated in the pressure transfer stage;When the stress decreases,the electromagnetic radiation intensity decreases to the trough;When shear failure or tensile failure occurs,the electromagnetic radiation intensity caused by rock block fracture rises sharply;Under the action of post failure stress wave,the friction between secondary fracture and fracture surface will lead to the cumulative increase of electromagnetic radiation.(2)At the same time,the uniaxial compression test results show that the microseismic signal,electromagnetic radiation signal and the stress and strain of the material have great coupling,and the microseismic signal and electromagnetic radiation signal will fluctuate in the compaction stage,elastic deformation stage,plastic deformation stage and failure stage.(3)Mine microseismic and electromagnetic radiation signals show the characteristics of synchronous response.In the process of transmitting the far-field focal stress wave to the sensor near the roadway,the reception of electromagnetic radiation signal will lag in time due to the influence of joint surface,rock fracture and other factors.