Acoustic Emission of Coal in the Postlimiting Deformation State

The features of acoustic emission in coal samples in the state of pre- and postlimiting deformation are considered. It is shown that in the postlimiting deformation stages and in the transient period, a contrary change is observed in a correlation coefficient of the acoustic emission activity recorded in the upper and lower portions of a sample; whereas in the prelimiting deformation stages, this change is consistent. It is proposed to recognize the stages of deformation by the correlation coefficient of recorded in different zones: a positive coefficient corresponds to the prelimiting stage of deformation, and a negative one corresponds to the postlimiting stage.