单轴受压岩石破坏全过程声发射特征研究

STUDIES ON ACOUSTIC EMISSION CHARACTERISTICS OF UNIAXIAL COMPRESSIVE ROCK FAILURE

在刚性试验机上,对单轴受压岩石破坏全过程进行声发射试验,得到了岩石破坏全过程力学特征和声发射特征,包括岩石应力-应变曲线、声发射事件数等,研究了声发射事件数(AE数)、事件率与应力、时间之间的关系。研究表明:岩石在一次性加载过程中,不是所有的岩石都具有典型的Kaiser效应的声发射特征点;在弹性阶段的初期和后期,随着应力水平的增加岩石声发射显著增加,特别在弹塑性高应力阶段,岩石声发射增长迅速;岩样在试验接近峰值强度时单位时间内的应力增长速度减小,声发射事件率出现明显下降,即出现相对平静阶段;声发射事件率在不同应力水平变化很大,峰值强度后的声发射现象仍然明显,其声发射特征随岩样破坏形式的不同而不同。

Experiments on acoustic emission (AE) characteristics of full-regime rock failure are carried out on stiffness test machine (STM). The mechanical properties of rocks and acoustic emission characteristics, including full-regime curves, AE counts and AE rate, are obtained. The relations among AE counts, AE rate, stress levels, and time are analyzed. The results show that the Kaiser effect does not occur for every rock samples subjected to simple loading. During the initial and late stages of elastic domains, AE counts increase rapidly with the increase of stress level. But when the curve is near to the peak, AE counts drop obviously, which means that there is a relatively tranquil period. The AE rates change dramatically in different stages. In post-peak region, AE events stay evident and the AE characteristics depend on the failure type of rocks.