钙质砂一维压缩回弹过程中声发射特征试验研究  

EXPERIMENTAL STUDY OF ACOUSTIC EMISSION CHARACTERISTICS DURING ONE-DIMENSIONAL COMPRESSION REBOUND OF CAL-CARE-OUS SAND

作　　者：吴永洁 魏厚振[3] 李肖肖 王志兵[1,2] 孟庆山 王新志[3] WU Yongjie;WEI Houzhen;LI Xiaoxiao;WANG Zhibing;MENG Qingshan;WANG Xinzhi(College of Civil Engineering and Architecture,Guilin University of Technology,Guilin 541004,China;Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering,Guilin 541004,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China)

机构地区：[1]桂林理工大学土木与建筑工程学院,桂林541004 [2]广西岩土力学与工程重点实验室,桂林541004 [3]中国科学院武汉岩土力学研究所,岩土力学与工程国家重点实验室,武汉430071

出　　处：《工程地质学报》2021年第6期1711-1721,共11页Journal of Engineering Geology

基　　金：国家自然科学基金(资助号:41877260,41877267);中国科学院战略性先导科技专项(资助号:XDA13010200).

摘　　要：为了揭示钙质砂在一维压缩回弹作用下的压缩变形、颗粒破碎特性以及声发射规律,对钙质砂进行了3种相对密实度下不同粒组的一维压缩回弹实验和声发射实验。通过对不同粒组、不同相对密实度的钙质砂进行一维压缩实验和同步的声发射实时监测,获得其压缩、回弹和声发射特性,最后通过筛分获得实验后的颗粒粒径分布,得出相对破碎势B_(r)。实验结果表明:钙质砂的压缩变形由颗粒位置调整和破碎两部分组成,其中颗粒破碎是产生压缩变形的主要因素,回弹曲线近似一条直线,表明压缩变形为不可恢复的塑形变形;压力相同时颗粒粒径越大,相对破碎势B_(r)越大。颗粒形状不同致使颗粒间填充作用与嵌合作用不同,影响颗粒的滑移与重排列,进而影响颗粒的压缩变形。两种砂的声发射计数率随粒径增大而增大,且都集中出现在800~3200 kPa的压缩阶段,钙质砂的压缩变形及破碎特性与其声发射特征具有一致性,钙质砂声发射计数率与时间关系曲线和应力与时间关系曲线吻合较好,可通过声发射计数率与时间关系曲线来反映钙质砂的力学特性。钙质砂存在一个声发射事件最少的“临界孔隙比”,本次实验中1~2mm钙质砂临界孔隙比为1.33~1.41,试样的初始孔隙比偏离该临界值时,声发射活动会有不同程度提高。This paper aims to reveal the compressive deformation,particle breakage characteristics,and acoustic emission laws of calcareous sand.The one-dimensional compression-resilience tests and synchronous acoustic emission tests were carried out on calcareous sand with different particle size fractions under three different relative densities.By sieving analysis,the relative breakage(B_(r))was obtained based on the particle size distribution after the test.The experimental results showed that the compressive deformation of calcareous sand is caused by the particle rearrangement and particle breakage.The particle breakage is the major factor behind this phenomenon.The rebound curve is approximately a straight line,indicating that the compressive deformation is an irreversible plastic deformation.Under the same stress,the larger the particle size,the greater the B_(r).The different shapes of the particles result in different interparticle filling and interlocking effects,which affects the sliding and rearrangement of the particles,and then influences the compressive deformation of the particles.The acoustic emission counts rate of the two kinds of sand increases with the increase of the particle size,and both appear mainly in the compression phase between 800kPa and 3200kPa.The compressive deformation and breakage characteristics of calcareous sand are consistent with their acoustic emission laws.The relation curves between counts rate and time are in good agreement with the stress-time curves.The mechanical characteristics of the calcareous sand can be reflected based on the counts rate-time curves.For calcareous sand,a“critical void ratio”exists with the fewest acoustic emission events.In this study,its value of calcareous sand with a particle size of 1~2mm is 1.33~1.41.When the initial void ratio of the sample deviates from this critical value,the acoustic emission activities would increase in varying degrees.

关 键 词：钙质砂 声发射 一维压缩 颗粒破碎 

分 类 号：P588.212.3[天文地球—岩石学]