ON THE ISSUE OF ANALYSIS OF ACOUSTIC EMISSION EVENT STATISTIC ON DATA OF SINGLE SENSOR IN ROCK THERMAL FRACTURE EXPERIMENTS

Abstract

Authors examine the problem of estimation of b-value for energy distribution of thermal acoustic emission (TAE) events on basis of amplitude distribution of TAE impulses. Impulses are registered by single TAE sensor. Authors have analyzed the effect of factors, associated with elastic waves propagation, on the energy of impulses. The analysis shows, that effect of elastic waves absorption in heated sample is the most significant from these factors. Two events of energy distribution are considered – with one and two sub-functions. It has shown, that the same b-value of registered impulse amplitude distribution and initial event distribution is observed if only b-value is stable in all TAE-event energy range (one sub-function). In this situation, there is one characteristic generation mechanism of events in all sample volume. But if b-value is not stable in different energy ranges (two sub-functions), then elastic waves absorption in the sample distorts initial distribution. Authors propose technique of “true” b-value estimation on basis of distribution analysis of registered TAE impulses in several amplitude subranges.