变加载速率砂岩声发射特征及损伤本构模型

研究加载速率对岩石声发射特性的影响,可以推断加载过程中岩石内部的性态变化,有助于揭示岩体的失稳破坏机制。利用WAW-1000型试验机及PCI-2型声发射仪研究了受加载速率影响的砂岩单轴压缩声发射特性。结果表明:不同加载速率下,砂岩试件的破坏形式有单向剪切破坏、双向剪切破坏和轴向劈裂破坏3种破坏形态。加载速率对砂岩试件的声发射特征也有显著影响:加载速率较高时,砂岩声发射撞击幅值维持较高水平,撞击事件贯穿整个加载阶段,试件内部声发射数量少而集中;加载速率越高,砂岩累计声发射计数增长越快。以时间为中间变量,拟合出考虑加载速率情况下,砂岩应变与累计声发射计数的关系,推导出基于加载速率、声发射累计振铃计数的砂岩损伤本构模型。

The Acoustic Emission Characteristics and Damage Constitutive Model of Sandstone under Variable Loading Rates

Researching the influence of different loading rates on the acoustic emission characteristics of rock, helps detect the internal behavior changes during the loading process, and revealing the instability mechanism of rock mass. The acoustic emission characteristics of sandstone in uniaxial compression experiment were studied under different loading rates by WAW-1000 testing machine and PCI-2 acoustic emission apparatus. The results show that there are three failure models of sandstone specimens under different loading rates, including unidirectional shear failure, bidirectional shear failure and axial splitting failure. The loading rate has a significant influence on the acoustic emission characteristics of sandstone specimens: when the specimen is loaded with high rate, the amplitude of acoustic emission event is maintained at a high level, acoustic emission hit runs through the entire loading phase, and the acoustic emission event in rock internal is little and concentrated; The higher the loading rate is, the faster the cumulative acoustic emission count increase. Taking the time as an intermediate variable, the relationship of strain and the cumulative acoustic emission count were fitted by considering different loading rates. The damage constitutive model of sandstone was deduced based on the cumulative acoustic emission count and the loading rate.