岩盐三轴蠕变声发射特征研究

Creep acoustic emission of rock salt under triaxial compression

利用四川大学MTS815电液伺服岩石试验系统和PCI-2声发射监测仪对岩盐进行蠕变加载试验,根据试验数据分析了岩盐蠕变前两个阶段的声发射活动特征。试验结果表明,三轴条件下,声发射特征参数,振铃计数率、能量均与蠕变速率成正比;声发射特征参数累积变化曲线与蠕变曲线走势基本相同。围压不变的情况下,较高的轴向应力能够加快试样的蠕变速率,声发射活动也有所增强,表现为AE定位点增多、振铃计数率和能量增大,以及累积振铃计数和累积能量的增加。通过对声发射事件点进行还原,为研究岩盐蠕变长期强度以及损伤演化提供了依据。利用G-P算法,计算岩盐在蠕变各时间段的声发射分维值,总结出呈上升-下降-波动的规律,通过分形特征为研究岩盐内部破坏的稳定性提供依据。

To study and analyze the acoustic emission activity characteristics in the first and stable phases of salt creep, a series of triaxial creep compression tests are carried out using MTS815 flex test GT rock mechanics test system and PCI-2 acoustic emission(AE) monitoring system. The results show: under the triaxial condition, the characteristic parameters of AE such as ringing count rate and energy are proportional to the creep rate. The curve tendency of AE characteristic parameters and creep rate are basically the same. Under the constant confining pressure, the higher axial stress can accelerate the creep rate, and the AE activities also increase, which are characterized by the increase of AE incident points, ringing count rate, energy, cumulative ringing count and cumulative energy. At the same time, through the reduction of points of AE events point, it provides a basis for the study on the long-term time strength and creep damage evolution of salt rock. The creep fractal dimension values of AE of rock salt in various periods are calculated using the G-P algorithm. The laws of rise-fall-fluctuation are summarized. It may that provide the basis for studying the stability of the internal damage of rock salt