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通过改变恒幅荷载条件下的上限应力、下限应力以及加载速率等试验条件,基于声发射技术对盐岩疲劳损伤特征进行试验研究。试验发现,盐岩声发射信号出现在加载阶段和卸载初期,而砂岩声发射信号一般集中出现在上限应力处;盐岩疲劳寿命对下限的依赖程度大于砂岩;随着上限应力的增大,盐岩声发射振铃数增多。加载速率的提高会加速盐岩的疲劳破坏。通过对比声发射振铃数累计曲线和应变累计曲线,发现两者有很好的对应关系,说明二者在反映盐岩疲劳损伤时具有一致性。最后对盐岩进行3级变幅荷载试验,发现第3级声发射振铃数比相同上、下限应力的恒幅荷载条件下多,说明变幅荷载造成的盐岩损伤比恒幅荷载条件下严重。
By changing the test conditions such as the upper limit stress, the lower limit stress and the loading rate under constant amplitude load, the characteristics of the fatigue damage of salt rock are studied based on the acoustic emission technique. It is found that acoustic emission signals of salt rock appear during loading and initial unloading, while acoustic emission signals of sandstone generally appear at upper stress. The fatigue life of salt rock is more dependent on lower limit than sandstone. With the increase of upper stress, Rock sound emission ring number increased. The increase of loading rate will accelerate the fatigue damage of salt rock. By comparing the accumulated curve of ringing number and the cumulative strain curve of acoustic emission, it is found that there is a good correspondence between the two, indicating that they are consistent in reflecting the fatigue damage of salt rock. Finally, the rock salt three-level luffing load test and found that the third level of acoustic emission ring than the same number of the same, the lower limit of the constant amplitude load conditions, indicating the rock salt damage caused by amplitude load than the constant amplitude load conditions serious.