堆石料加载与流变过程中塑性应变方向研究
|
摘要
确定塑性应变增量方向是建立土体弹塑性本构模型的核心之一,弹塑性理论中通常假定塑性应变增量方向仅与应力状态有关,与应力增量无关。流变试验是一种应力状态恒定的特殊试验,应力增量为零,所有应变均为塑性变形。研究流变过程中塑性应变方向与应力状态的关系及其与加载过程中塑性应变方向的差异,对于建立土体弹塑性本构模型具有重要价值。通过对某抽水蓄能电站筑坝堆石料的大型三轴压缩试验和三轴流变试验,分别研究了加载和流变过程中剪胀比与应力比之间的关系。结果表明,三轴压缩和三轴流变过程中,堆石料的剪胀比均随着应力比的增加而减小,且相同三轴压缩应力状态下,堆石料的流变剪胀比明显大于加载剪胀比,即流变过程中堆石料剪缩性比三轴压缩过程中的剪缩性更为强烈。因此,采用相同的塑性势函数同时确定加载塑性应变方向和流变黏塑性应变方向是不恰当的,建立考虑堆石料流变的弹塑性模型时应该选用不同的应力剪胀方程或塑性势函数。
The determination of the incremental plastic strain direction(IPSD) is one of the kernels in elastoplastic constitutive models. It is generally assume that the IPSD depends only on the stress states and is not influenced by the stress increments. A creep test is a special experiment that the stress state is kept constant without increment and the strains are purely plastic. Studying the dependence of the IPSD during creeping upon the stress states and its difference from that during loading may offer valuable reference to constitutive modeling. In this study, large-scale triaxial compression experiments and triaxial creep experiments are conducted on a typical rockfill material used in a pumped storage power station. The relationships between the dilatancy ratio and the stress ratio during both loading and creeping are investigated, respectively. It is found that in both kinds of experiments the dilatancy ratio decreases nonlinearly when the stress ratio increases, and the positive dilatancy ratio during creeping is considerably higher than that during loading under the same stress state. That is to say, the shear volume contraction behavior is much more evident during creeping than that during loading. Therefore, it is irrational to use the same potential function to determine the IPSDs during both loading and creeping. Different stress dilatancy equations or different plastic potential functions are required in establishing constitutive models considering the creep behavior of rockfill materials.
The determination of the incremental plastic strain direction(IPSD) is one of the kernels in elastoplastic constitutive models. It is generally assume that the IPSD depends only on the stress states and is not influenced by the stress increments. A creep test is a special experiment that the stress state is kept constant without increment and the strains are purely plastic. Studying the dependence of the IPSD during creeping upon the stress states and its difference from that during loading may offer valuable reference to constitutive modeling. In this study, large-scale triaxial compression experiments and triaxial creep experiments are conducted on a typical rockfill material used in a pumped storage power station. The relationships between the dilatancy ratio and the stress ratio during both loading and creeping are investigated, respectively. It is found that in both kinds of experiments the dilatancy ratio decreases nonlinearly when the stress ratio increases, and the positive dilatancy ratio during creeping is considerably higher than that during loading under the same stress state. That is to say, the shear volume contraction behavior is much more evident during creeping than that during loading. Therefore, it is irrational to use the same potential function to determine the IPSDs during both loading and creeping. Different stress dilatancy equations or different plastic potential functions are required in establishing constitutive models considering the creep behavior of rockfill materials.
引文
[1]CLEMENTS R P.Post-construction deformation of rockfill dams[J].Journal of Geotechnical Engineering,1984,110(7):821-840.
[2]DASCAL O.Post-construction deformation of rockfill dams[J].Journal of Geotechnical Engineering,1987,113(1):46-59.
[3]FU Z Z,WANG T B,CHEN S S.Field settlement observations made on four concrete face rockfill dams[C]//Proc 4th Int Conf on Civil Engineering and Urban Programing.LIU Y M,FU D,TONG Z X,et al,eds.London:Taylor&Francis,2016:589-595.
[4]CHARLES J A,WATTS K S.The influence of confining pressure on the shear strength of compacted rockfill[J].Géotechnique,1980,30(4):353-367.
[5]BAUER E,FU Z Z,LIU S H.Hypoplastic constitutive modelling of wetting deformation of weathered rockfill materials[J].Front Archit Civ Eng China,2010,4(1):78-91.
[6]OLDECOP L A,ALONSO E E.Theoretical investigation of the time-dependent behaviour of rockfill[J].Géotechnique,2007,57(3):289-301.
[7]ZHANG B Y,CHEN T,PENG C,et al.Experimental study on loading-creep coupling effect in rockfill material[J].International Journal of Geomechanics,2017.DOI:10.1061/(ASCE)GM.1943-5622.0000938.
[8]ZHANG B Y,WANG J G,SHI R F.Time-dependent deformation in high concrete-faced rockfill dam and separation between concrete face slab and cushion layer[J].Computers and Geotechnics,2004,31(7):559-573.
[9]程展林,丁红顺.堆石料蠕变特性试验研究[J].岩土工程学报,2004,26(4):473-476.(CHENG Zhan-lin,DING Hong-shun.Creep test for rockfill[J].Chinese Journal of Geotechnical Engineering,2004,26(4):473-476.(in Chinese))
[10]ZHOU W,CHANG X L,ZHOU C B,et al.Creep analysis of high concrete-faced rockfill dam[J].International Journal for Numerical Methods in Biomedical Engineering,2010,26(11):1477-1492.
[11]ZHOU W,HUA J J,CHANG X L.Settlement analysis of the Shuibuya concrete-face rockfill dam[J].Computers and Geotechnics,2011,38(2):269-280.
[12]LADE P V,LIU C T.Experimental study of drained creep behavior of sand[J].Journal of Engineering Mechanics,1998,124(8):912-920.
[13]KARIMPOUR H,LADE P V.Creep behavior in Virginia Beach sand[J].Canadian Geotechnical Journal,2013,50(11):1159-1178.
[14]AUGUSTESEN A,LIINGAARD M,LADE P V.Evaluation of time-dependent behavior of soils[J].International Journal of Geomechanics,2004,4(3):137-156.
[15]LADE P V,LIGGIO C D,NAM J.Strain rate,creep and stress drop-creep experiments on crushed coral sand[J].Journal of Geotechnical and Geoenvironmental Engineering,2009,135(7):941-953.
[16]INDRARATNA B,WIJEWARDENA L S S,BALASUBRAMANIAM A S.Large-scale triaxial testing of Grey Wacke rockfill[J].Géotechnique,1993,43(1):37-51.
[17]TAPIAS M,ALONSO E E,GILI J.A particle model for rockfill behavior[J].Géotechnique,2015,65(12):975-994.
[18]石北啸,蔡正银,陈生水.温度变化对堆石料变形影响的试验研究[J].岩土工程学报,2016,38(增刊2):299-305.(SHI Bei-xiao,CAI Zheng-yin,CHEN Sheng-shui.Experiments on influence of temperature on deformation of rock fills[J].Chinese Journal of Geotechnical Engineering,2016,38(S2):299-305.(in Chinese))
[19]FU Z Z,CHEN S S,PENG C.Modeling cyclic behavior of rockfill materials in a framework of generalized plasticity[J].International Journal of Geomechanics,2014,14(2):191-204.
[20]DESRUES J,CHAMBON R,MOKNI M,et al.Void ratio evolution inside shear bands in triaxial sand specimens studied by computed tomography[J].Géotechnique,1996,46(3):529-546.
[21]FINNO R J,HARRIS W W,MOONEY M A,et al.Shear bands in plane strain compression of loose sand[J].Géotechnique,1997,47(1):149-165.
[22]LADE P V.Instability,shear banding and failure in granular materials[J].International Journal of Solids and Structures,2002,39(13/14):3337-3357.
[23]DUNCAN J M,CHANG C Y.Nonlinear analysis of stress and strain in soils[J].Journal of the Soil Mechanics and Foundations Division,1970,96(SM5):1629-1653.
[24]SCHOFILED A,WROTH P.Critical state soil mechanics[M].London:Mc Graw-Hill,1968.
[25]PRADHAN T B S,TATSUOKA F,SATO Y.Experimental stress-dilatancy relations of sand subjected to cyclic loading[J].Soils and Foundations,1989,29(1):45-64.
[26]KONG X J,LIU J M,ZOU D G,et al.Stress-dilatancy relationship of Zipingpu gravel under cyclic loading in triaxial stress states[J/OL].International Journal of Geomechanics,2016.DOI:10.1061/(ASCE)GM.1943-5622.0000584.
[27]BEEN K,JEFFERIES M.Stress-dilatancy in very loose sand[J].Canadian Geotechnical Journal,2004,41(5):972-989.
[28]XIAO Y,LIU H L,CHEN Y M,et al.Strength and dilatancy behavior of dense modeled rockfill material in general stress space[J/OL].International Journal of Geomechanics,2016.DOI:10.1061/(ASCE)GM.1943-5622.0000645.
[29]KUWANO R,JARDINE R J.On measuring creep behaviour in granular materials through triaxial testing[J].Canadian Geotechnical Journal,2002,39(5):1061-1074.
[30]MARACHI N D.Strength and deformation characteristics of rockfill materials[D].Berkeley:University of California,1969.
[31]孔宪京,刘京茂,邹德高.堆石料尺寸效应研究面临的问题及多尺度三轴试验平台[J].岩土工程学报,2016,38(11):1941-1947.(KONG Xian-jing,LIU Jing-mao,ZOU De-gao.Scale effect of rockfill and multiple-scale triaxial test platform[J].Chinese Journal of Geotechnical Engineering,2016,38(11):1941-1947.(in Chinese))
[32]MA G,CHANG X L,ZHOU W,et al.Mechanical response of rockfills in a simulated true triaxial test:a combined FDEM study[J].Geomechanics and Engineering,2014,7(3):317-333.
[33]马刚,周伟,常晓林,等.堆石体三轴剪切试验的三维细观数值模拟[J].岩土工程学报,2011,33(5):746-753.(MA Gang,ZHOU Wei,CHANG Xiao-lin,et al.3D mesoscopic numerical simulation of triaxial shear tests for rockfill[J].Chinese Journal of Geotechnical Engineering,2011,33(5):746-753.(in Chinese))
[34]王占军,陈生水,傅中志.堆石料流变的黏弹塑性本构模型研究[J].岩土工程学报,2014,36(12):2188-2194.(WANG Zhan-jun,CHEN Sheng-shui,FU Zhong-zhi.Viscoelastic-plastic constitutive model for creep deformation of rockfill materials[J].Chinese Journal of Geotechnical Engineering,2014,36(12):2188-2194.(in Chinese))
[2]DASCAL O.Post-construction deformation of rockfill dams[J].Journal of Geotechnical Engineering,1987,113(1):46-59.
[3]FU Z Z,WANG T B,CHEN S S.Field settlement observations made on four concrete face rockfill dams[C]//Proc 4th Int Conf on Civil Engineering and Urban Programing.LIU Y M,FU D,TONG Z X,et al,eds.London:Taylor&Francis,2016:589-595.
[4]CHARLES J A,WATTS K S.The influence of confining pressure on the shear strength of compacted rockfill[J].Géotechnique,1980,30(4):353-367.
[5]BAUER E,FU Z Z,LIU S H.Hypoplastic constitutive modelling of wetting deformation of weathered rockfill materials[J].Front Archit Civ Eng China,2010,4(1):78-91.
[6]OLDECOP L A,ALONSO E E.Theoretical investigation of the time-dependent behaviour of rockfill[J].Géotechnique,2007,57(3):289-301.
[7]ZHANG B Y,CHEN T,PENG C,et al.Experimental study on loading-creep coupling effect in rockfill material[J].International Journal of Geomechanics,2017.DOI:10.1061/(ASCE)GM.1943-5622.0000938.
[8]ZHANG B Y,WANG J G,SHI R F.Time-dependent deformation in high concrete-faced rockfill dam and separation between concrete face slab and cushion layer[J].Computers and Geotechnics,2004,31(7):559-573.
[9]程展林,丁红顺.堆石料蠕变特性试验研究[J].岩土工程学报,2004,26(4):473-476.(CHENG Zhan-lin,DING Hong-shun.Creep test for rockfill[J].Chinese Journal of Geotechnical Engineering,2004,26(4):473-476.(in Chinese))
[10]ZHOU W,CHANG X L,ZHOU C B,et al.Creep analysis of high concrete-faced rockfill dam[J].International Journal for Numerical Methods in Biomedical Engineering,2010,26(11):1477-1492.
[11]ZHOU W,HUA J J,CHANG X L.Settlement analysis of the Shuibuya concrete-face rockfill dam[J].Computers and Geotechnics,2011,38(2):269-280.
[12]LADE P V,LIU C T.Experimental study of drained creep behavior of sand[J].Journal of Engineering Mechanics,1998,124(8):912-920.
[13]KARIMPOUR H,LADE P V.Creep behavior in Virginia Beach sand[J].Canadian Geotechnical Journal,2013,50(11):1159-1178.
[14]AUGUSTESEN A,LIINGAARD M,LADE P V.Evaluation of time-dependent behavior of soils[J].International Journal of Geomechanics,2004,4(3):137-156.
[15]LADE P V,LIGGIO C D,NAM J.Strain rate,creep and stress drop-creep experiments on crushed coral sand[J].Journal of Geotechnical and Geoenvironmental Engineering,2009,135(7):941-953.
[16]INDRARATNA B,WIJEWARDENA L S S,BALASUBRAMANIAM A S.Large-scale triaxial testing of Grey Wacke rockfill[J].Géotechnique,1993,43(1):37-51.
[17]TAPIAS M,ALONSO E E,GILI J.A particle model for rockfill behavior[J].Géotechnique,2015,65(12):975-994.
[18]石北啸,蔡正银,陈生水.温度变化对堆石料变形影响的试验研究[J].岩土工程学报,2016,38(增刊2):299-305.(SHI Bei-xiao,CAI Zheng-yin,CHEN Sheng-shui.Experiments on influence of temperature on deformation of rock fills[J].Chinese Journal of Geotechnical Engineering,2016,38(S2):299-305.(in Chinese))
[19]FU Z Z,CHEN S S,PENG C.Modeling cyclic behavior of rockfill materials in a framework of generalized plasticity[J].International Journal of Geomechanics,2014,14(2):191-204.
[20]DESRUES J,CHAMBON R,MOKNI M,et al.Void ratio evolution inside shear bands in triaxial sand specimens studied by computed tomography[J].Géotechnique,1996,46(3):529-546.
[21]FINNO R J,HARRIS W W,MOONEY M A,et al.Shear bands in plane strain compression of loose sand[J].Géotechnique,1997,47(1):149-165.
[22]LADE P V.Instability,shear banding and failure in granular materials[J].International Journal of Solids and Structures,2002,39(13/14):3337-3357.
[23]DUNCAN J M,CHANG C Y.Nonlinear analysis of stress and strain in soils[J].Journal of the Soil Mechanics and Foundations Division,1970,96(SM5):1629-1653.
[24]SCHOFILED A,WROTH P.Critical state soil mechanics[M].London:Mc Graw-Hill,1968.
[25]PRADHAN T B S,TATSUOKA F,SATO Y.Experimental stress-dilatancy relations of sand subjected to cyclic loading[J].Soils and Foundations,1989,29(1):45-64.
[26]KONG X J,LIU J M,ZOU D G,et al.Stress-dilatancy relationship of Zipingpu gravel under cyclic loading in triaxial stress states[J/OL].International Journal of Geomechanics,2016.DOI:10.1061/(ASCE)GM.1943-5622.0000584.
[27]BEEN K,JEFFERIES M.Stress-dilatancy in very loose sand[J].Canadian Geotechnical Journal,2004,41(5):972-989.
[28]XIAO Y,LIU H L,CHEN Y M,et al.Strength and dilatancy behavior of dense modeled rockfill material in general stress space[J/OL].International Journal of Geomechanics,2016.DOI:10.1061/(ASCE)GM.1943-5622.0000645.
[29]KUWANO R,JARDINE R J.On measuring creep behaviour in granular materials through triaxial testing[J].Canadian Geotechnical Journal,2002,39(5):1061-1074.
[30]MARACHI N D.Strength and deformation characteristics of rockfill materials[D].Berkeley:University of California,1969.
[31]孔宪京,刘京茂,邹德高.堆石料尺寸效应研究面临的问题及多尺度三轴试验平台[J].岩土工程学报,2016,38(11):1941-1947.(KONG Xian-jing,LIU Jing-mao,ZOU De-gao.Scale effect of rockfill and multiple-scale triaxial test platform[J].Chinese Journal of Geotechnical Engineering,2016,38(11):1941-1947.(in Chinese))
[32]MA G,CHANG X L,ZHOU W,et al.Mechanical response of rockfills in a simulated true triaxial test:a combined FDEM study[J].Geomechanics and Engineering,2014,7(3):317-333.
[33]马刚,周伟,常晓林,等.堆石体三轴剪切试验的三维细观数值模拟[J].岩土工程学报,2011,33(5):746-753.(MA Gang,ZHOU Wei,CHANG Xiao-lin,et al.3D mesoscopic numerical simulation of triaxial shear tests for rockfill[J].Chinese Journal of Geotechnical Engineering,2011,33(5):746-753.(in Chinese))
[34]王占军,陈生水,傅中志.堆石料流变的黏弹塑性本构模型研究[J].岩土工程学报,2014,36(12):2188-2194.(WANG Zhan-jun,CHEN Sheng-shui,FU Zhong-zhi.Viscoelastic-plastic constitutive model for creep deformation of rockfill materials[J].Chinese Journal of Geotechnical Engineering,2014,36(12):2188-2194.(in Chinese))