基于砂岩三轴加载过程声发射与波速变化的峰前特征应力识别研究  

Identification of pre-peak characteristic stress of sandstone under triaxial loading based on acoustic emission and wave velocity variation

作　　者：张旭龙 张盛[1,2] 王龙飞 荣腾龙 周锐 ZHANG Xulong;ZHANG Sheng;WANG Longfei;RONG Tenglong;ZHOU Rui(College of Energy Science and Engineering,Henan Polytechnic University,Jiaozuo,Henan 454001,China;Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization,Jiaozuo,Henan 454001,China)

机构地区：[1]河南理工大学能源科学与工程学院,河南焦作454001 [2]煤炭安全生产与清洁高效利用省部共建协同创新中心,河南焦作454001

出　　处：《岩石力学与工程学报》2023年第11期2711-2726,共16页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51674101,52004081);河南省高校基本科研业务费专项资金项目(NSFRF210306)。

摘　　要：为了准确识别不同围压条件下岩石加载过程中的峰前特征应力,在GCTS RTX–3000试验机上对砂岩标准试样进行围压分别为0,10,30,50和70 MPa的假三轴试验,采用超声波测试系统和声发射采集系统同时监测,获得砂岩加载过程中超声波波速的变化规律和声发射定位事件的分布特征,提出一种能够从声发射采集的数据中屏蔽超声波干扰信号的方法。结果表明:试样纵、横波波速随着围压的增加呈二次函数关系,随着轴压的增加呈现增长–平稳–下降的变化规律,横波波速总是先于纵波波速出现下降趋势,横波相较于纵波对损伤更加敏感;对比体积应变、声发射、超声波和动态弹性参数的变化规律,能够准确判定试样的峰前特征应力,闭合应力对应横波波速上升结束时刻,起裂应力对应横波波速开始下降时刻以及动弹性模量的拐点,损伤应力能够通过纵波波速开始下降、声发射信号快速上升时刻和体积应变的拐点共同确定;声发射定位能够直观反应试样的破坏模式,低围压条件下,试样发生劈裂–剪切混合破坏,高围压条件下,试样发生剪切破坏。该研究有助于准确识别岩石受载时的峰前特征应力,深入了解不同应力条件下岩石的损伤特征,对深部地下工程岩体的稳定性评价有重要的理论意义。In order to accurately identify the pre-peak characteristic stress in the process of rock loading under different confining pressures,the pseudo triaxial tests with confining pressures of 0,10,30,50 and 70 MPa were carried out on sandstone standard samples using the GCTS RTX–3000 testing machine.The ultrasonic testing system and acoustic emission acquisition system were used to monitor at the same time,and the variation law of ultrasonic wave velocity and the distribution characteristics of acoustic emission location events during sandstone loading were obtained.A method that can shield ultrasonic interference signals from acoustic emission dates was proposed.The results show that the compression and shear wave velocities of the sample show a quadratic function relationship with the increase of confining pressure.With the increase of the axial pressure,the compression and shear wave velocities of the sample show a law of growth,stability and decline.The shear wave velocities always show a downward trend before the compression wave velocities,and the shear wave is more sensitive to damage than the compression wave.The pre-peak characteristic stress can be accurately determined by comparing the change rules of volume strain,acoustic emission,ultrasonic and dynamic elastic parameters.The closure stress corresponds to the end of the rise of the shear wave velocity,the initiation stress corresponds to the beginning of the fall of the shear wave velocity and the inflection point of the dynamic elastic modulus,and the damage stress can be determined jointly by the beginning of the decline of the compression wave velocity,the rapid rise of the acoustic emission signal and the inflection point of the volumetric strain.Acoustic emission positioning can directly reflect the failure mode of the sample.Under low confining pressure,the sample will undergo split shear mixed failure,while under high confining pressure,the sample will undergo shear failure.This study is helpful to accurately identify the prepeak characteristic

关 键 词：岩石力学 三轴压缩 声发射 峰前特征应力 

分 类 号：TU45[建筑科学—岩土工程]