红砂岩不同蠕变阶段声发射振幅与能量特征研究

为认识岩石蠕变过程中的声发射特征,对红砂岩进行了分级循环加卸载试验,研究了试件在减速蠕变、等速蠕变与加速蠕变阶段的声发射振幅与能量特征。试验结果表明:在减速蠕变阶段,声发射振幅与能量随时间的增长而减小;而后,在等速蠕变阶段,声发射振幅与能量基本趋于稳定,并且两参数的平均值与方差小于减速蠕变阶段。在加速蠕变阶段,声发射振幅与能量发生跃迁的频率增大。在此阶段,声发射能量平均值与方差和声发射振幅方差,大于减速蠕变与等速蠕变阶段。以上声发射特征说明,相对于等速蠕变阶段,减速蠕变阶段微破裂的尺度相对较大;而在加速蠕变阶段,微破裂在更大尺度的范围内发生。试件损伤主要发生在减速蠕变与加速蠕变阶段。

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.