单轴压缩下片岩应力记忆持续时间试验研究

Experimental study on retention time of stress memory in schist under uniaxial compression

为了研究时间对岩石应力记忆的影响,利用岩石试验机和SDAES数字声发射检测仪对2次加载时间间隔分别为2,7,15,30和45 d的片岩进行单轴压缩条件下的声发射Kaiser效应试验。试验结果表明：首次加载7 d后再次加载Kaiser效应明显,30 d后还可以观察到Kaiser效应,而45 d后Kaiser效应已难以辨认;随着首次加载与第二次加载间隔时间的增长,岩石Kaiser效应逐渐衰退;首次加载的应力水平影响岩石Kaiser效应的消退,介于岩石强度的30%~80%之间,岩石记忆先前应力的能力最好。

In order to study the influence of time on rock stress memory , an experimental study has been performed to investigate the Kaiser effect of acoustic emission on schist at time interval of 2 days, 7 days, 15 days, 30 days and 45 days between the first and second loading under the condition of uniax-ial compression, by making use of rock testing machine, as well as a testing apparatus of AE, SDAES. The test results show that with the increase of time interval between two loading cycles, Kaiser effect in rock gradually disappears and the effect is well-pronounced at time interval of 7 days and remains de-tectable within 30 days, while it is hard to be detected after more than 45 days. The stress level of the first loading affects the fade of Kaiser effect in rock, and rock’s memory ability of precious stress is the best when the stress level of the first loading is of between 30%to 80%of rock strength.