Research On Infrared Radiation Characterization Of Coal And Rock Failure And Infrared Method Of Mining Coal

Coal and rock power disaster is one of the main disasters in the mine,causing a lot of property losses and casualties to the society.Therefore,people have made a lot of research on the generation mechanism of coal and rock power,which has produced many methods for monitoring and predicting coal and rock power disasters,such as acoustic emission(AE)method,microseismic method,electromagnetic radiation method and so on.Infrared radiation method is a non-contact geophysical method for monitoring coal and rock dynamic disasters.It has excellent characteristics such as visualization and high accuracy.Its infrared radiation temperature(IRT)and infrared radiation thermal image cloud images are destroyed with coal and rock in time and space.The characteristics of stress distribution and coal damage in the process have a good correspondence.Therefore,this paper uses a combination of laboratory experiments and field experiments,and uses the established thermal and acoustic response information acquisition system for coal sample instability to study and analyze the infrared radiation precursor information characteristics of coal sample instability based on the critical slowing theory.The infrared radiation method and the acoustic emission method were used to uniaxially compress the prefabricated fractured coal samples with different angles of type I(single fracture)and the same angle and different loading rates of type I and type II(geese-shaped fractures)prefabricated fractured coal samples.Experiment,analyze and study the comprehensive response characteristics of sound and heat in the process of damage.The infrared radiation temperature and infrared thermal image cloud of the coal body in the driving face and the mining face were tested on the spot,and the infrared radiation characteristic law of the mining coal body was studied.The specific research results are as follows:(1)The change trend of the maximum infrared radiation temperature(MIRT)and the average infrared temperature(AIRT)of the coal samples in the early and middle stages of loading is basically the same.The maximum infrared temperature in the late stage of loading is increasing at the damage point of the coal sample,and the main rupture occurs When the maximum infrared radiation temperature rises sharply,the average infrared temperature does not show a significant change at the time of the main rupture;both the variance and the autocorrelation coefficient are affected by the window length and lag step,but the variance curve is greatly affected by the window length;Compared with the precursor of infrared cooling and the sudden increase of infrared heating,variance predicts coal sample instability and destruction more accurately.(2)Different prefabricated crack angles have a significant effect on the mechanical properties of coal samples.The stress and strain of coal samples increase with the angle and show a quadratic function relationship,and the elastic modulus and angle show a linear increasing relationship;the prefabricated crack angle ??45°,the destruction pattern of coal samples is mainly airfoil cracks,and local coal body shedding occurs;when prefabricated cracks 90°>?>45°,the crack propagation modes of prefabricated coal samples are airfoil cracks and reverse wings Type fissures develop together,accompanied by coal lumps;the fracture type of 90° prefabricated cracked coal samples is split failure;the infrared radiation and acoustic emission characteristics of prefabricated cracked coal samples are staged,and the difference between acoustic emission positioning and infrared radiation The isotherm thermal image cloud can clearly reflect the crack propagation.With the increase of the prefabricated crack angle,the average infrared radiation temperature change has the same regularity as the peak of the acoustic emission count,showing a trend of decreasing first and then increasing.The highest infrared radiation temperature The amount of change and the cumulative peak value of the acoustic emission are random.(3)Under different loading rates,the fluctuations of infrared radiation temperature change during the destruction process of type I and type II prefabricated fractured coal samples increase with the loading rate;for different loading rate conditions,the infrared radiation temperature curve change and acoustic emission of prefabricated fractured coal samples The number of events is positively correlated;the intensity of acoustic emission events is closely related to the size of the loading rate and the degree of development and destruction of coal fractures.(4)The average infrared radiation temperature of the coal body in the driving face increases with the initial gas flow velocity q,showing four stages of change: slow growth stage,linear growth stage,accelerated growth stage,and when the initial gas velocity exceeds a certain value At this time,its infrared radiation temperature will no longer increase but keep a certain temperature change,that is,in the stable operation stage,the change of coal body temperature is no longer affected by the initial velocity q of gas gushing,which is much more affected by environmental conditions.(5)The distribution of the infrared radiation temperature of the coal body of the coal wall on the inlet and outlet side of the mining face along the coal seam is basically consistent with the distribution of the stress field in the coal body in front of the working face,and the red high temperature areas of the coal body on both sides of the mining face are mainly concentrated In the middle area of the coal body of the roadway,it can be seen that the stress in the middle area of the coal wall of the two roadways is more concentrated than that in the upper and lower areas.There are 42 figures,6 tables,101 references in this thesis.