基于声发射实验岩石破坏前兆特征研究

Study on Precursory Characteristics of Rock Failure Based on Acoustic Emission Experiment

在单轴加载条件下,进行岩石破裂失稳全过程声发射实验研究,得到岩石破裂过程中的应力-应变曲线、声发射参数与时间的关系。选取累计AE数、AE能量释放率、震级-频度关系中的b值随时间的变化规律研究了岩石失稳破坏的前兆信息。结果表明:在初始加载阶段,声发射数量很少;在岩石弹性变形阶段后期和塑性变形阶段,累计声发射数快速增加;声发射能量在岩石破裂过程中相当长的一段时间内保持低释放率,而在破坏前释放明显;在岩石失稳破坏前,b值出现快速下降现象,多数岩石试件声发射b值岩石破坏前下降到最低值。这些前兆特征可以为现场岩体声发射监测预报技术的应用提供依据,以提高岩体稳定性监测预报的准确率。

Experiments on acoustic emission （AE） characteristics of complete rock failure process are carried out under uniaxial loading. The stressstrain curve, the relation between AE characteristics and time are obtained. The relation of the time with cumulative AE events, AE energy release rate, and the b -value of the relation between the magnitude and frequency are selected to study the precursory characteristics of rock failure. The results show that during the initial loading phase, AE events are very few and its cumulative number rapidly increases at the late phase of the rock elastic deformation and at the plastic phase; the AE energy keeps a low release rate for a long time during the rock fracturing process but exhibits an evident release just before the rock failure. Before the rock instability failure, b -value will drop quickly, with that of most rock samples reaching the lowest value before the rock failure, These precursory characteristics are significant for the field application of AE monitoring and forecasting technology so as to improve the accuracy of in-situ rock mass monitoring and forecast.