ACOUSTIC EMISSION AND FRACTAL CHARACTERISTICS OF COAL ROCK SAMPLES UNDER TRIAXIAL COMPRESSION

In order to study the acoustic emission and the fractal characteristics of coal samples under triaxial compression, experiments were carried out by using the RMT-150C rock mechanics test system and the CDAE-1 acoustic emission instrument under different confining pressure(5MPa, 10MPa, 15MPa), and the acoustic emission count, the cumulative count and the acoustic emission sequence fractal characteristics of coal sample were obtained. It is shown that the coal has different acoustic emission characteristics under different confining pressures, the higher the confining pressure is, the more precursor information will be obtained. The coal samples show the fractal characteristics under different confining pressures, and the fractal characteristics will strength with the increase of the confining pressure. The acoustic emission sequence fractal dimension value will experience a process of volatility-rise-drop during the process of coal sample failure, which can be regarded as the precursor information to predict the collapse of the coal rock masses.