胶结颗粒料力学行为与声发射信号特征
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摘要
胶结颗粒料是由胶结流体填充密实堆积颗粒体部分孔隙得到,硬化后的胶结流体限制颗粒的转动和移动,赋予颗粒材料整体性力学行为。该文基于自流可控灌浆技术制备胶结颗粒料试样,其中采用高强度的陶瓷球作为颗粒料骨架,胶结流体为自密实水泥净浆。通过单轴压缩试验研究了胶结基质含量对胶结颗粒料力学行为的影响,同时采用声发射量测系统对试样加载过程进行监测。研究结果表明:胶结颗粒料以脆性破坏为主,峰值前的应力应变曲线可分为压密阶段和线弹性段;峰值后,低胶结量的试样存在应变硬化现象和第二峰值,第二峰值强度远低于材料的峰值强度,随着胶结基质含量的提高,应变硬化现象逐渐消失。胶结颗粒料的峰值强度随胶结基质体积分数线性变化且拟合直线通过原点。压密阶段应变长度随着胶结基质体积分数的增加呈线性增大,而胶结基质体积分数对线弹性段应变长度无明显影响。当胶结颗粒料的胶结基质含量较低时,其声发射信号主要集中在峰值点附近;提高胶结基质含量,声发射信号产生时间前移至线弹性段;进一步增加胶结基质体积分数,声发射事件在压密阶段中期出现,并在线弹性段快速增强后维持在高水平。该研究成果有助于进一步理解胶结颗粒料的力学行为,同时对砂岩、砾岩、堆石混凝土和灌浆胶结砂土也具有重要参考价值。
Cemented granular materials(CGM)are composed of densely packed particles bound together by a cement matrix that partially fills the interstitial pores which provides considerable stiffness to the material.This study investigated the mechanical behavior and acoustic emission(AE)response characteristics during uniaxial compression of an artificial cemented granular material made from high alumina ceramic beads combined with a self-compacting cement paste.The samples were fabricated using the rock-filled concrete technique without disturbing the granular backbone.The results show that the compressive strength is a linear function of the matrix volume fraction.Brittle fracture is the most significant mechanical behavior.Compaction in the linear-elastic regime is the dominant behavior in the pre-peak strength region with strain-softening accompanied by strain-hardening after the peak strength.The extent of the compaction phase linearly increases with the matrix volume fraction.However,the extent of the linear-elastic phase is independent of the matrix volume fraction.For the samples with little matrix material,an AE signal occurred when the material strength approached the peak value.The AE signals of samples with more matrix material mainly occurred in the initial stages of the elastic phase.The AE signals of samples with higher matrix volume fractions were found at the mid-term stage of the compaction phase and remained high until the samples failed.The results will help to further understand the mechanical behavior of cemented granular materials,and also provide an important reference for the studies of sandstone,conglomerate,rockfill concrete and grouted sands.
Cemented granular materials(CGM)are composed of densely packed particles bound together by a cement matrix that partially fills the interstitial pores which provides considerable stiffness to the material.This study investigated the mechanical behavior and acoustic emission(AE)response characteristics during uniaxial compression of an artificial cemented granular material made from high alumina ceramic beads combined with a self-compacting cement paste.The samples were fabricated using the rock-filled concrete technique without disturbing the granular backbone.The results show that the compressive strength is a linear function of the matrix volume fraction.Brittle fracture is the most significant mechanical behavior.Compaction in the linear-elastic regime is the dominant behavior in the pre-peak strength region with strain-softening accompanied by strain-hardening after the peak strength.The extent of the compaction phase linearly increases with the matrix volume fraction.However,the extent of the linear-elastic phase is independent of the matrix volume fraction.For the samples with little matrix material,an AE signal occurred when the material strength approached the peak value.The AE signals of samples with more matrix material mainly occurred in the initial stages of the elastic phase.The AE signals of samples with higher matrix volume fractions were found at the mid-term stage of the compaction phase and remained high until the samples failed.The results will help to further understand the mechanical behavior of cemented granular materials,and also provide an important reference for the studies of sandstone,conglomerate,rockfill concrete and grouted sands.
引文
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[4]金峰,安雪晖,石建军,等.堆石混凝土及堆石混凝土大坝[J].水利学报,2005,36(11):1347-1352.JIN F,AN X H,SHI J J,et al.Study on rock-fill concrete dam[J].Journal of Hydraulic Engineering,2005,36(11):1347-1352.(in Chinese)
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[6]RADJAF,PREECHAWUTTIPONG I,PEYROUX R.Cohesive granular texture[M]//VERMEER P A,HERRMANN H J,LUDING S.et al.Continuous and discontinuous modelling of cohesive-frictional materials.Berlin,Heidelberg:Springer,2001,568:149-162.
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[10]尹贤刚.受载岩石与混凝土声发射特性对比实验研究[J].四川大学学报(工程科学版),2010,42(2):82-87.YIN X G.Contrast study on the acoustic emission characteristics of compressive rock and concrete through experiment[J].Journal of Sichuan University(Engineering Science Edition),2010,42(2):82-87.(in Chinese)
[11]纪洪广,侯昭飞,张磊,等.混凝土材料声发射信号的频率特征及其与强度参量的相关性试验研究[J].应用声学,2011,30(2):112-117.JI H G,HOU Z F,ZHANG L,et al.Experimental studies on the frequency characteristics of acoustic emissions in concrete material and its dependences on strength parameters[J].Applied Acoustics,2011,30(2):112-117.(in Chinese)
[12]郭庆华,郤保平,李志伟,等.混凝土声发射信号频率特征与强度参数的相关性试验研究[J].中南大学学报(自然科学版),2015,46(4):1482-1488.GUO Q H,XI B P,LI Z W,et al.Experimental research on relationship between frequency characteristics of acoustic emission and strength parameter in concrete[J].Journal of Central South University(Science and Technology),2015,46(4):1482-1488.(in Chinese)
[13]AFIFIPOUR M,MOAREFVAND P.Mechanical behavior of bimrocks having high rock block proportion[J].International Journal of Rock Mechanics and Mining Sciences,2014,65:40-48.
[14]BERNABY,FRYER D T,HAYES J A.The effect of cement on the strength of granular rocks[J].Geophysical Research Letters,1992,19(14):1511-1514.
[15]PALACIOS M,PUERTAS F,BOWEN P,et al.Effect of PCs superplasticizers on the rheological properties and hydration process of slag-blended cement pastes[J].Journal of Materials Science,2009,44(10):2714-2723.
[16]ROUSSEL N,STEFANI C,LEROY R.From mini-cone test to Abrams cone test:Measurement of cement-based materials yield stress using slump tests[J].Cement and Concrete Research,2005,35(5):817-822.
[17]ASTM International.Standard test method for compressive strength of cylindrical concrete specimens:ASTM C39/C39M-2010[S].West Conshohocken,USA:ASTM International,2011.
[2]DELENNE J Y,TOPIN V,RADJAI F.Failure of cemented granular materials under simple compression:Experiments and numerical simulations[J].Acta Mechanica,2009,205(1-4):9-21.
[3]ALVARADO G,LUI N,COOP M R.Effect of fabric on the behaviour of reservoir sandstones[J].Canadian Geotechnical Journal,2012,49(9):1036-1051.
[4]金峰,安雪晖,石建军,等.堆石混凝土及堆石混凝土大坝[J].水利学报,2005,36(11):1347-1352.JIN F,AN X H,SHI J J,et al.Study on rock-fill concrete dam[J].Journal of Hydraulic Engineering,2005,36(11):1347-1352.(in Chinese)
[5]ISMAIL M A,JOER H A,RANDOLPH M F,et al.Cementation of porous materials using calcite[J].Géotechnique,2002,52(5):313-324.
[6]RADJAF,PREECHAWUTTIPONG I,PEYROUX R.Cohesive granular texture[M]//VERMEER P A,HERRMANN H J,LUDING S.et al.Continuous and discontinuous modelling of cohesive-frictional materials.Berlin,Heidelberg:Springer,2001,568:149-162.
[7]DELENNE J Y,EL YOUSSOUFI M S,CHERBLANC F,et al.Mechanical behaviour and failure of cohesive granular materials[J].International Journal for Numerical and Analytical Methods in Geomechanics,2004,28(15):1577-1594.
[8]OUADFEL H,ROTHENBURG L.“Stress-force-fabric”relationship for assemblies of ellipsoids[J].Mechanics of Materials,2001,33(4):201-221.
[9]纪洪广,张天森,蔡美峰,等.混凝土材料损伤的声发射动态检测试验研究[J].岩石力学与工程学报,2000,19(2):165-168.JI H G,ZHANG T S,CAI M F,et al.Experimental study on concrete damage by dynamic measurement of acoustic emission[J].Chinese Journal of Rock Mechanics and Engineering,2000,19(2):165-168.(in Chinese)
[10]尹贤刚.受载岩石与混凝土声发射特性对比实验研究[J].四川大学学报(工程科学版),2010,42(2):82-87.YIN X G.Contrast study on the acoustic emission characteristics of compressive rock and concrete through experiment[J].Journal of Sichuan University(Engineering Science Edition),2010,42(2):82-87.(in Chinese)
[11]纪洪广,侯昭飞,张磊,等.混凝土材料声发射信号的频率特征及其与强度参量的相关性试验研究[J].应用声学,2011,30(2):112-117.JI H G,HOU Z F,ZHANG L,et al.Experimental studies on the frequency characteristics of acoustic emissions in concrete material and its dependences on strength parameters[J].Applied Acoustics,2011,30(2):112-117.(in Chinese)
[12]郭庆华,郤保平,李志伟,等.混凝土声发射信号频率特征与强度参数的相关性试验研究[J].中南大学学报(自然科学版),2015,46(4):1482-1488.GUO Q H,XI B P,LI Z W,et al.Experimental research on relationship between frequency characteristics of acoustic emission and strength parameter in concrete[J].Journal of Central South University(Science and Technology),2015,46(4):1482-1488.(in Chinese)
[13]AFIFIPOUR M,MOAREFVAND P.Mechanical behavior of bimrocks having high rock block proportion[J].International Journal of Rock Mechanics and Mining Sciences,2014,65:40-48.
[14]BERNABY,FRYER D T,HAYES J A.The effect of cement on the strength of granular rocks[J].Geophysical Research Letters,1992,19(14):1511-1514.
[15]PALACIOS M,PUERTAS F,BOWEN P,et al.Effect of PCs superplasticizers on the rheological properties and hydration process of slag-blended cement pastes[J].Journal of Materials Science,2009,44(10):2714-2723.
[16]ROUSSEL N,STEFANI C,LEROY R.From mini-cone test to Abrams cone test:Measurement of cement-based materials yield stress using slump tests[J].Cement and Concrete Research,2005,35(5):817-822.
[17]ASTM International.Standard test method for compressive strength of cylindrical concrete specimens:ASTM C39/C39M-2010[S].West Conshohocken,USA:ASTM International,2011.