Study On Infrared Acoustic Emission Characteristics Of Coal Mass Failure Precursor Under Water Injection Condition

In has burst tendency of coal seam mining, usually by coal seam affusion unloading pressure to ensure safety in production, but the production process with a the way of coal body under the action of high stress local sometimes still have impact accidents. In order to reduce the occurrence of the impact hazard and improve the predictability and predictability of the local danger region, the monitoring and research of the precursor information of the water injection coal body in the local dangerous area is particularly critical. In view of the above problems, the contact through acoustic emission equipment and non contact infrared equipment with shock tendency of coal injection(natural water absorption of coal body and saturated absorption of coal body and natural water content coal) for uniaxial load combination monitoring test, in order to from inside and outside two aspects to monitor coal loss of failure evolution process, thus revealing with impact trend coal risk of local regional force lost stability of infrared radiation and acoustic emission precursory variation.The main research results are as follows:(1) The evolution of AE in the front of the instability of coal structure can be divided into three stages, the acoustic emission quiet period, the weak active period of acoustic emission and the strong active period of acoustic emission. Coal moisture increased, coal samples under the same load bearing time is shortened, the local instability phenomenon appears earlier, the sudden increase of acoustic emission also appears earlier. The sudden increase of the AE signal before the coal sample instability is obvious and has a period of calm. The appearance of this phenomenon can be used as a basis for judging the precursor of coal sample instability.(2) The trend of AIRT- time evolution and stress time evolution of different water cut coal samples are similar, and the AIRT before the coal sample structure is decreased with the decrease of the stress of the structure, and the trend is more obvious with the greater the water.The infrared anomaly zone of coal samples before the instability of infrared thermal images appear obvious, the specimen with "beep beep beep" sound. The bigger the moisture content of coal sample is, the smaller the temperature difference between the infrared thermal image and the surrounding environment is, but the more obvious the infrared anomaly is. The appearance of the first infrared anomaly area can be used as the basis for judging the precursor of coal sample instability.(3) Through the contrast analysis of different coal water content in the structure loses the steady evolution in the process of acoustic emission and infrared radiation characteristics ofinformation shows: acoustic emission signal increased only know aggravated injury but I do not know when the coal sample failure, although the infrared thermography appearance time than AE signals appeared later, however, than the AE signal ended early. Therefore, the infrared anomaly point or the belt or the surface appearance can be more intuitive and obvious prediction of coal sample instability damage. By using the characteristic parameters of acoustic emission and infrared thermal imaging, the damage model of coal is established,and the evolution law of the damage of different water cut coal samples is analyzed from two aspects of internal and external. Through the experimental study, it is found that the two kinds of monitoring tools can be complementary to each other, and the combined monitoring can predict the failure of the specimen.