Study On Infrared Characterization And Energy Law Of Coal Rock Friction Failure Process

In the process of coal mining,the fracture and friction of the roof coal and rock in the goaf is likely to produce high temperature or sparks,and ignite the gas accumulated in the goaf,causing a gas explosion or fire,causing a large number of property losses and casualties,and seriously threatening the safety of coal mine production.In order to accurately describe the evolution of temperature and energy in the process of coal-rock frictional failure,the characteristics of the influence of water content on the energy dissipation process of coal-rock frictional failure are studied.This paper establishes a coal-rock double-shear friction infrared radiation temperature information acquisition system,and compares and analyzes the maximum infrared radiation temperature change law of coal and rock under different friction speeds and different moisture contents and the distribution characteristics of the infrared radiation difference cloud map.The friction speed and moisture content are analyzed.The influence of infrared radiation temperature evolution characteristics;based on the rescaled range analysis method(R/S analysis method),the long-range correlation and fractal characteristics of the time series of the highest infrared radiation temperature signal of coal and rock samples under different friction speeds are studied;The changes of infrared radiation temperature and surface current of coal and rock samples under different water content during the double-shear friction process are discussed.The energy equation of friction process is deduced from the two angles of frictional work and infrared radiation energy based on the energy equation of fault friction heat generation.The law of energy change of coal and rock samples under different water content is analyzed.The specific research results are as follows:(1)In the natural and saturated state,the friction curve of coal and rock samples has similar laws.Among them,the maximum static friction force is positively correlated with the friction speed,and the static friction phase duration is negatively correlated with the friction speed.In the process of double-shear friction,the maximum infrared radiation temperature of natural coal and rock samples is positively correlated with time and friction speed,and the maximum temperature increases with the increase of friction speed.Among them,the sandstone sample has the most obvious heating characteristics.The above-mentioned infrared temperature change law is suitable for water-saturated coal and rock samples.(2)Comparative analysis of the infrared difference cloud images at different moments of the friction process,and it is found that the number of high temperature points on the friction surface of the sample gradually increases and diffuses into the interior;the brightness and isotherm density of the infrared difference cloud images of different lithological samples show different distribution characteristics,among which sandstone The cloud image of the sample has the highest brightness temperature,and the cloud image of the granite sample has the lowest brightness temperature.(3)The results of the rescaled range analysis(R/S analysis)of the highest infrared radiation temperature of coal and rock show that the Hurst exponent H of coal and rock samples at different friction speeds is greater than 0.5,and is positively correlated with the friction speed.It shows that there is a long-range correlation between the highest infrared radiation temperature of the sample and the time,and the heating range is positively correlated with the friction speed,that is,the longer the friction time,the higher the highest infrared radiation temperature,the faster the friction speed,and the greater the heating range;at the same time,coal and rock During the friction process,the infrared radiation temperature change has a good corresponding relationship with the surface current response characteristics.(4)By introducing the fault friction slip heat generation equation and the normalized analysis of the gray value of the infrared thermal image,the friction work equation and the infrared radiation energy equation in the friction process are established;the research has obtained the coal and rock test under different water content conditions.This is the value of the frictional work E.Due to the weakening effect of water,the frictional work E and infrared radiation energy Q both decrease with the increase of water content.At the same time,the proportion of infrared radiation energy Q in the frictional work E also gradually decreases.There are 55 pictures,9 tables and 71 references.