高径比对砂岩单轴压缩声发射特性的影响研究

岩石尺寸效应对声发射特性的影响对于利用声发射技术监测岩石失稳破坏具有重要的实践意义。本文选择不同高径比的长石细砂岩试样开展单轴压缩声发射试验,探讨尺寸效应对岩石声发射事件数、振铃计数、峰值频率等声发射特性参数的影响。研究结果表明:根据岩石试件撞击数的增长速率,将试件破坏阶段分为突变期、平静期、爆发期三个阶段,随着岩石试件高径比增加,声发射的撞击数相应增加,增加趋势与试件高径比的增加呈近似线性相关关系;随着岩石试件高径比的减小,振铃计数突变期时间占比相应减小,平静期振铃计数也相应减小;岩石试件的加载破坏的峰值频率主要呈现高频和低频两个集中分布区,随着高径比减小,岩石试件加载破坏的峰值频率逐渐由低频区向高频区过渡,同时峰值频率的离散性也在增加。试验成果丰富了岩石声发射特性的基础数据,并可为实际工程中声发射技术的实践应用提供参考。

Experimental study on the effect of height-to-diameter ratio on acoustic emission characteristics of sandstone under uniaxial compression condition

The study of rock size effect on the acoustic emission(AE)characteristics is of great significance for the use of acoustic emission technology to monitor rock damage.Fine arkose samples with different height-to-diameter ratios are selected for uniaxial compression and acoustic emission test to analyze the effect of size effect on acoustic emission characteristics,including the number of AE events,AE ringing counts,and AE peak frequency.The results show that the AE events can be divided into three stages including abrupt phase,calm phase,and failure phase based on the increasing rate of AE events.With the height-to-diameter ratio of rock specimen increasing,the number of AE events accordingly increases,and the increasing trend is approximately linearly related to the height-to-diameter ratio.As the height-to-diameter ratio decreases,the proportion of time associated with the AE ring counts during the abrupt phase decreases,and the number of AE ring counts during the calm phase accordingly decreases.The peak frequency distribution of the rock specimens mainly shows two concentrated distribution bands,that is,the high frequency band and the low frequency band,respectively.As the height-to-diameter ratio decreases,the peak frequency near rock failure gradually shifts from the low frequency band to the high frequency band,and the dispersion of peak frequency increases as well.The experimental results enrich the basic data of the AE rock characteristics and provide a reference for the practical application of AE technology in actual engineering.