红砂岩变形演化及声发射主频特征实验研究

以声发射系统和数字散斑相关方法作为实验观测手段,开展红砂岩试件变形场演化及声发射主频特征实验研究。通过单轴加载方式,对一种红砂岩试件加载全过程中的变形场演化、声发射主频信息进行分析,研究红砂岩试件变形场演化与声发射主频分布范围、事件率对应关系以及声发射主频的能量特征。研究结果表明:低主频声发射事件在变形局部化启动时刻开始出现且数量不断增加,随着变形局部化带错动速率增大,声发射主频分布范围显著增加;在红砂岩试件变形局部化阶段,低主频声发射事件率与高主频声发射事件率的量值接近,但量值较小;在应力峰值点处,低主频声发射事件率远大于高主频声发射事件率;在界面滑动阶段,高、低主频声发射事件率量值均较大;红砂岩试件变形破坏过程中,高能量声发射事件主要分布在低主频范围内,低能量声发射事件在高、低主频范围内均有分布。

Experimental study on deformation evolution and acoustic emission dominant-frequency characteristics of red sandstone

The digital speckle correlation method was adopted to measure the deformation field.Acoustic emission information was monitored by acoustic emission system.This paper concentrated on acoustic emission characteristics of deformation field evolution of red sandstone rocks.By uniaxial compression,the deformation filed evolution,the correspondence between deformation filed evolution and acoustic emission dominant-frequency range and acoustic emission event rate,energy characteristics of acoustic emission dominant-frequency of red sandstone were studied.The results show that:At the start time of deformation localization,the low dominant-frequency acoustic emission events began to occur,then the number increased.The dominant-frequency distribution of acoustic emission events increased with the increase of dislocation rate.The quantity of low and higher dominant-frequency acoustic emission event rate are close,but the quantity is small.When the macroscopic crack developed of rock specimen,the low dominant-frequency event rate is larger.And the higher dominant-frequency event rate is smaller.At the peak of stress,the low dominant-frequency event rate is much higher than the high dominant-frequency event rate.The value of high and low dominant-frequency acoustic emission event rate is higher at the interface sliding stage.In the process of failure of rock specimens,the high energy acoustic emission events are mainly distributed in the low dominant-frequency range.Low energy acoustic emission events are distributed both in high dominant-frequency and low dominant-frequency range.