动静组合加载下岩石破坏的声发射实验

Acoustic emission experiment of rock failure under coupled static-dynamic load

在霍普金森(SHPB)实验系统上进行了动静组合加载下岩石破坏的声发射实验,获得了动静组合加载下花岗岩声发射能量的变化规律。结果表明,动静组合加载下声发射能量规律呈现出2种明显不同的特征:I型,声发射峰值能量之后,能量迅速衰减,到加载末期,能量出现一定的回升,产生了"拐点";II型,声发射峰值能量之后,能量衰减相对I型较慢,且不出现"拐点"。分别讨论了轴向静载和动载应变率对声发射能量的影响:声发射峰值能量随轴向静载增大而减小;当轴向静载位于岩石弹性段时,峰前声发射能量随静载缓慢增大,当轴向静载超过弹性段时,峰前声发射能量随轴向静载增大而急剧增大;声发射峰值能量和峰前能量均随动载应变率增大而减小。本研究对于重新寻求动静组合加载下岩石破坏的声发射前兆规律具有理论和实践意义。

The acoustic emission（AE） tests of rock failure were made on the SHPB test system and the law of the AE energy was obtained under coupled static-dynamic load. The AE energy presents two different features：mode I,the energy decays rapidly after the peak of the energy,however,the energy rises at the end of the loading and the ＂inflection point＂ appears; mode II,the energy decays slowly after the peak of the energy and the ＂inflection point＂ does not appear. The effect of the axial static load and impact on the AE energy was analyzed. The results show that the peak value of the AE energy decreases with the increase of the axial static load; when the axial static load is located at the elastic stage,the pre-peak of the AE energy increases slowly; when the axial static load exceeds the elastic stage,the pre-peak of the AE energy increases rapidly with the increase of the axial static load. The peak and pre-peak of the AE energy decrease with the increase of the dynamic strain rate. It is useful for both theory and practice to seek the precursory characteristics of the AE of rock mass under coupled static-dynamic load.