Fundamental Research On Propagation Law Of Ultra-Wideband Radar Wave In Coal And Localiztion

During mine accidents,scientific and rapid emergency rescue is an effective measure to reduce the casualties of people in distress.At present,there are two types of emergency mine rescue methods,namely underground roadway rescue and ground drilling and rescue,respectively.There have been successful drill rescue cases,such as the collapse of the Pingyi gypsum mine of Shandong Province in 2015,and four trapped people were rescued by the methods of ground drilling rescue.It creates the first time in China meamwhile it is also the world's third successful case of drilling assistance,which has milestone significance in the history of China's mine rescue.Although the rescue of Pingyi mine disaster relief has been successful,the problems encountered in the rescue are still worthy of study and reflection.For example,when taking a drilling for exploration,if the final hole position of the drilling hole deviates from the design position or the roadway near the target position collapses,most of the borehole life information detection devices(such as video/audio,infrared thermal imaging etc.)do not have the capability of penetration detection,so what methods should be adopted to penetrate the coal and rock caving objects for the detection of life information?Sun Jiping and others believe that ultra-wideband life detection radar technology is the future research direction to solve this problem.In this article,basic research work has been carried out.The dielectric constants and resistivities of coals with different metamorphic degrees were tested.The variation of electrical parameters with frequency was analyzed and the corresponding fitting function was given.The influencing factors of coal electrical parameters are analyzed from the aspects of coal molecular composition,microstructure and surface structure,that is to say,the internal relationship between the coefficients of the above function and the degree of metamorphism is studied.The key parameters of ultra-wideband radar wave propagation in coal are analyzed.Theoretical analysis and simulation of the law of ultra-wideband radar wave propagation in coal,and proposed a method for locating people in distress.Dielectric constant and resistivity are the basic physical quantities of ultra-wideband radar wave propagation in coal.In order to study its variation with the degree of deterioration and frequency,the dielectric constant and conductivity of lignite,long flame coal,gas coal,lean coal and anthracite are tested by using the Concept 80 Broadband Dielectric Spectroscopy Test System.In order to study the variation law of the coefficient of dielectric constant and frequency function,that is,the intrinsic factor of the dielectric constant with the degree of deterioration of coal.Coal industrial analysis,elemental analysis,SEM analysis and mercury intrusion experiments were carried out in the third chapter of this paper.In order to study the change law of the coefficient in resistivity and frequency function,that is,the intrinsic factor of resistivity with coal metamorphism.X-ray diffraction analysis,all-element analysis,nuclear magnetic resonance analysis and other experiments are carried out in the fourth chapter of this paper.Through the above studies,the UWB radar wave propagation control equations in coal have been constructed.The law of ultra-wideband radar wave propagation in coal is simulated and analyzed though the finite-difference time-domain method with GprMax software.The Ricker excitation source with a antenna center frequency of 500 MHz is the best detection method.The human target reflected wave is a negative peak,and the reflected wave at the interface between the coal pillar and the excavation lane is a positive peak.The intensity of human reflected wave amplitude is greater than the intensity of reflected wave amplitude at the interface.The higher the frequency is,the faster the electromagnetic wave propagates in the coal.The intensity of the human body reflected wave amplitude is exponentially related to the thickness of the coal pillars,and based on this,the idea of establishing a database of coal pillar thickness and amplitude intensity spectral for each mining area is proposed.This research results of this paper can provide important references for the design and development and the analysis of exploration data of mine drilling ultra-wideband radar,and it has important scientific value and practical significance for mine accident rescue.