Early‐warning signal recognition methods in flawed sandstone subjected to uniaxial compression

Abstract

AbstractTo investigate the precursor information related to rock fracturing, a series of indoor uniaxial compression tests are conducted on flawed sandstone. Four methods of identifying potential precursors to rock catastrophic failure, namely, cumulative acoustic emission (AE) activity, AE b‐value, inter‐event time function, and critical slowing down, are discussed. The results show that the four precursory identification methods can reasonably identify the early‐warning signal, subcritical failure, and final catastrophic failure of flawed sandstone involving the whole loading process. The minimum b‐value is correspondingly obtained when the specimen approaches failure. The inter‐event rate of AE multi‐parameters shows a significant increase, following a power law distribution. By comparison with the other three precursor identification methods, the time intervals of AE parameters‐based variance between the precursory signal and its corresponding tripping points become increasingly shortened. Additionally, the precursory characteristics of variance of AE multi‐parameters are more accurate and reliable than that of autocorrelation coefficient.