单轴压缩下岩石声发射定位实验的影响因素分析

INFLUENTIAL FACTORS OF ACOUSTIC EMISSION LOCATION EXPERIMENT OF ROCK UNDER UNIAXIAL COMPRESSION

应用声发射及其定位技术,在单轴压缩载荷作用下,采用实验方法观察重庆细砂岩试样破裂失稳过程中其内部微裂纹孕育、发展的三维空间演化模式,研究岩石声发射定位实验的影响因素。实验结果表明:(1)端部摩擦对岩石破裂过程中的声发射特征影响显著,采用1∶1(质量比)硬脂酸和凡士林的混合物作为减摩剂进行AE定位实验,在试样初始压密阶段基本没有AE事件,取得较好的效果。(2)重庆细砂岩的AE定位事件主要分布在中部,呈散漫分布,两端没有明显的条带丛集现象,中部没有得到声发射定位事件的"空白区",通过与相关成果的对比,说明岩石的种类、构造和均匀程度是AE定位实验的主要影响因素之一。(3)加载方式和加载的控制方式会直接影响岩石试样破坏的进程和程度,从而影响AE事件。(4)通过重庆细砂岩试样疲劳荷载AE定位实验说明加载历史对AE时间序列及AE事件均有影响。以上实验和分析结果可以为岩石声发射定位实验的方案设计提供参考。

Acoustic emission（AE） technique can be used to monitor the microcracks development in the rock test samples continuously in real-time： it is better than other methods. AE location technique is employed to study crack initiation and propagation process of Chongqing sandstone. Also, the crack spatial evolution mode with loading time has been observed and the influential factors of AE location experiment of the sandstone have been discussed. The experimental results are displayed as follows. （1） The attrition of the tip of the sample has remarkable influence on AE characteristic in the rock failure process： and the mixture of the stearic acid and the vaseline（weight ratio 1 ： 1） is used as attrition-reduced agent to the AE location experiment. No AE event is found when the initial crack is closed： it will obtain a better effect. （2） The AE location of the Chongqing sandstone test sample mostly is distributed in central-section and assumes dispersion. No void space is shown in the central-section of the sample. Contrasted with the relevant studies, it is shown that the rock type, the structure and the level of uniformity are the major influential factors, （3） The load mode and the load control mode can directly affect the rock failure process so as to affect the AE events. （4） AE location experiment of the Chongqing sandstone test sample under fatigue load shows that the load history affects the AE time series and the AE events. The experimental and analytical results can afford useful help for the program design of AE location experiment of rocks.