Study on acoustic emission amplitude and energy characteristics of red sandstone in different creep stages

The studies on the characteristics of acoustic emission(AE) during rock creep process were carried out by virtue of step-cyclic loading and unloading tests on red sandstone.The amplitude and energy characteristics of acoustic emission were analyzed.The results show that the amplitude and energy of AE decline as load-time increases during decelerated creep process.When get into the steady creep stage,these two parameters tend towards stability and their mean values and the variances are smaller,compared with decelerated creep process.The transition frequencies of amplitude and energy become increased in the accelerated creep process,and their mean values and the variances are larger than the other stages.The AE characteristics mentioned above indicate that the micro-scale fracture in decelerated creep process is larger than steady creep process and smaller than accelerated creep process.The sample damages mainly occur in the decelerated creep and accelerated creep stage.