周期荷载作用下盐岩声发射特征试验研究

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。

Experimental research on acoustic emission property of salt rock under cyclic loading

The fatigue damage characteristic of salt rock is researched based on the acoustic emission(AE) technology by changing the upper limit stress,lower limit stress and loading rate.It is found that the AE count increases slowly with the stress increasing,but for sandstone,the AE count is intensive around the upper limit stress.The fatigue life of salt rock is more dependent on lower limit stress than sandstone.The higher the upper limit stress is,the more the AE count is,and the higher the loading rate is,the damage becomes much earlier.It is found that the AE cumulative curves are in keeping with strain curves which show that they can both show the fatigue damage process of salt rock.In the end,the constant amplitude load is instead by three-level variable amplitude load.The AE count becomes much more in the third level which shows that the variable amplitude load makes more serious fatigue damage in the salt rock than the constant amplitude load does.