堆石料颗粒形状对堆积密度及强度影响的离散元分析
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摘要
颗粒形状不仅反映颗粒的形成历史,更是影响堆石料物理力学性能的重要因素之一,值得深入研究。采用颗粒流程序PFC3D,根据实际颗粒形状建立不同球度的颗粒模型,并提出了数值试验中获取不同相对密实度试样的流程。讨论了球度对最大、最小孔隙比的影响,其结论与已有试验统计结果基本相符。分别以孔隙比和相对密实度为密度控制指标,对不同颗粒形状的试样进行等向固结和常规三轴试验,并分析了配位数、颗粒长轴各向异性、接触各向异性、结构各向异性等微观变量的变化规律。结果表明,当颗粒圆度较高且级配均匀时,球度对峰值摩擦角影响较小,主要影响残余摩擦角的大小。颗粒形状发生变化时,配位数影响试样强度但不起决定性作用,颗粒形状主要通过影响试样内接触以及接触力的各向异性程度来影响试样宏观表现。
Aggregate shape not only reflects the formation history, but also plays an important role in the mechanical properties of granular materials, and the effect of aggregate shape deserves further study. In this research, the three-dimensional particle flow code,FPC3D, is used and five particle models are generated according to the actual aggregate shape. The process of obtaining different relative density samples in numerical experiments is proposed. The effect of sphericity on the maximum and minimum void ratio is discussed, and the conclusion is basically consistent with the statistical results of the existing experiments. Numerical tests of isotropic compression and triaxial compression are carried out on the samples consisting of different shape aggregates, and the void ratio and relative density are selected as density control indexes respectively. The evolution of four micromechanical indexes with strain including coordination number, particle orientation, deviator fabric and branch vector is studied. The data show that when the particles are well-rounded, the sphericity has less influence on the peak friction angle. Instead, it mainly affects the residual friction angle. When the aggregate shape changes, the coordination number affects the strength but does not play a decisive role. The particle shape mainly influences the macroscopic performance by affecting the degree of anisotropy of contact and contact force in sample.
Aggregate shape not only reflects the formation history, but also plays an important role in the mechanical properties of granular materials, and the effect of aggregate shape deserves further study. In this research, the three-dimensional particle flow code,FPC3D, is used and five particle models are generated according to the actual aggregate shape. The process of obtaining different relative density samples in numerical experiments is proposed. The effect of sphericity on the maximum and minimum void ratio is discussed, and the conclusion is basically consistent with the statistical results of the existing experiments. Numerical tests of isotropic compression and triaxial compression are carried out on the samples consisting of different shape aggregates, and the void ratio and relative density are selected as density control indexes respectively. The evolution of four micromechanical indexes with strain including coordination number, particle orientation, deviator fabric and branch vector is studied. The data show that when the particles are well-rounded, the sphericity has less influence on the peak friction angle. Instead, it mainly affects the residual friction angle. When the aggregate shape changes, the coordination number affects the strength but does not play a decisive role. The particle shape mainly influences the macroscopic performance by affecting the degree of anisotropy of contact and contact force in sample.
引文
[1]VARADARAJAN A,SHARMA K G,VENKATACHALAM K,et al.Testing and modeling two rockfill materials[J].Journal of Geotechnical and Geoenvironmental Engineering,2003,129(3):206-218.
[2]HOLUBEC I,D'APPOLONIA E.Effect of particle shape on the engineering properties of granular soils[C]//Evaluation of Relative Density and Its Role in Geotechnical Projects Involving Cohesionless Soils.Los Angeles:ASTM,1973:304-318.
[3]CHUHAN F A,KJELDSTAD A,BJ?RLYKKE K,et al.Experimental compression of loose sands:relevance to porosity reduction during burial in sedimentary basins[J].Canadian Geotechnical Journal,2003,40(5):995-1011.
[4]LE PEN L M,POWRIE W,ZERVOS A,et al.Dependence of shape on particle size for a crushed rock railway ballast[J].Granular Matter,2013,15(6):849-861.
[5]BARRETT P J.The shape of rock particles,a critical review[J].Sedimentology,1980,27(3):291-303.
[6]CHO G C,DODDS J,SANTAMARINA J C.Particle shape effects on packing density,stiffness,and strength:natural and crushed sands[J].Journal of Geotechnical and Geoenvironmental Engineering,2006,133(11):591-602.
[7]刘清秉,项伟,崔德山,等.颗粒形状对砂土抗剪强度及桩端阻力影响机制试验研究[J].岩石力学与工程学报,2011,30(2):400-409.LIU Qing-bing,XIANG Wei,CUI De-shan,et al.Experimental study of effect of particle shapes on shear strength of sand and tip resistance of driven piles[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(2):400-409.
[8]CUNDALL P A,STRACK O D L.A discrete numerical model for granular assemblies[J].Geotechnique,1979,29(1):47-65.
[9]ROTHENBURG L,BATHURST R J.Micromechanical features of granular assemblies with planar elliptical particles[J].Geotechnique,1992,42(1):79-95.
[10]NG T T.Particle shape effect on macro-and microbehaviors of monodisperse ellipsoids[J].International Journal for Numerical and Analytical Methods in Geomechanics,2009,33(4):511-527.
[11]ZHOU W,HUANG Y,NG T T,et al.A geometric potential-based contact detection algorithm for egg-shaped particles in discrete element modeling[J].Powder Technology,2018,327:152-162.
[12]MIRGHASEMI A A,ROTHENBURG L,MATYAS E L.Influence of particle shape on engineering properties of assemblies of two-dimensional polygon-shaped particles[J].Geotechnique,2002,52(3):209-217.
[13]ZHOU W,MA G,CHANG X,et al.Influence of particle shape on behavior of rockfill using a three-dimensional deformable DEM[J].Journal of Engineering Mechanics,2013,139(12):1868-1873.
[14]ZHOU W,MA G,CHANG X,et al.Discrete modeling of rockfill materials considering the irregular shaped particles and their crushability[J].Engineering Computations,2015,32(4):1104-1120.
[15]TAPIAS M,ALONSO E E,GILI J.A particle model for rockfill behaviour[J].Geotechnique,2015,65(12):975-994.
[16]XU M,HONG J,SONG E.DEM study on the effect of particle breakage on the macro-and micro-behavior of rockfill sheared along different stress paths[J].Computers and Geotechnics,2017,89:113-127.
[17]ZHOU M,SONG E.A random virtual crack DEM model for creep behavior of rockfill based on the subcritical crack propagation theory[J].Acta Geotechnica,2016,11(4):827-847.
[18]ZHAO Z,SONG E.Particle mechanics modeling of creep behavior of rockfill materials under dry and wet conditions[J].Computers and Geotechnics,2015,68:137-146.
[19]周健,池毓蔚,池永,等.砂土双轴试验的颗粒流模拟[J].岩土工程学报,2000,22(6):701-704.ZHOU Jian,CHI Yu-wei,CHI Yong,et al.Simulation of biaxial test on sand by particle flow code[J].Chinese Journal of Geotechnical Engineering,2000,22(6):701-704.
[20]MATTHEW R K,KATALIN B.Sample size effect in discrete element simulations[C]//The 6th European Solid Mechanics Conference.Budapest:ESMC,2006.
[21]刘海涛,程晓辉.粗粒土尺寸效应的离散元分析[J].岩土力学,2009,30(增刊1):287-292.LIU Hai-tao,CHENG Xiao-hui.Discrete element analysis for size effects of coarse-grained soils[J].Rock and Soil Mechanics,2009,30(Suppl.1):287-292.
[22]EMERIAULT F,CLAQUIN C.Statistical homogenization for assemblies of elliptical grains:effect of the aspect ratio and particle orientation[J].International Journal of Solids and Structures,2004,41(21):5837-5849.
[23]SALOT C,GOTTELAND P,VILLARD P.Influence of relative density on granular materials behavior:DEMsimulations of triaxial tests[J].Granular Matter,2009,11(4):221-236.
[24]MINH N H,CHENG Y P.A DEM investigation of the effect of particle-size distribution on one-dimensional compression[J].Géotechnique,2013,63(1):44-53.
[25]中华人民共和国水利部.GB/T50123―1999土工试验方法标准[S].北京:中国计划出版社,1999.Ministry of Water Resources of the People's Republic of China.GB/T50123―1999 Standard for soil test method[S].Beijing:China Planning Press,1999.
[26]DELUZARCHE R,CAMBOU B,FRY J J.Modeling of rockfill behavior with crushable particles[C]//Numerical Modeling in Micromechanics via Particle Methods,Proceedings of the First International PFC Symposium.Gelsenkirchen:Heinz Konietzky,2002,6(7):219-224.
[27]DONEV A,CONNELLY R,STILLINGER F H,et al.Hypostatic jammed packings of nonspherical hard particles:ellipses and ellipsoids[J].Physical Review EStatistical Nonlinear&Soft Matter Physics,2006,75:051304.
[28]THORNTON C.Numerical simulations of deviatoric shear deformation of granular media[J].Geotechnique,2000,50(1):43-53.
[29]BOLTON M D,NAKATA Y,CHENG Y P.Micro-and macro-mechanical behaviour of DEM crushable materials[J].Geotechnique,2008,58(6):471-480.
[30]SATAKE M.Fabric tensor in granular materials[C]//IUTAM Conference on Deformation and Failure of Granular Materials.Delft:A.A.Balkema,1982:63-68.
[31]MAKSE H A,JOHNSON D L,SCHWARTZ L M.Packing of compressible granular materials[J].Physical Review Letters,2000,84(18):4160.
[2]HOLUBEC I,D'APPOLONIA E.Effect of particle shape on the engineering properties of granular soils[C]//Evaluation of Relative Density and Its Role in Geotechnical Projects Involving Cohesionless Soils.Los Angeles:ASTM,1973:304-318.
[3]CHUHAN F A,KJELDSTAD A,BJ?RLYKKE K,et al.Experimental compression of loose sands:relevance to porosity reduction during burial in sedimentary basins[J].Canadian Geotechnical Journal,2003,40(5):995-1011.
[4]LE PEN L M,POWRIE W,ZERVOS A,et al.Dependence of shape on particle size for a crushed rock railway ballast[J].Granular Matter,2013,15(6):849-861.
[5]BARRETT P J.The shape of rock particles,a critical review[J].Sedimentology,1980,27(3):291-303.
[6]CHO G C,DODDS J,SANTAMARINA J C.Particle shape effects on packing density,stiffness,and strength:natural and crushed sands[J].Journal of Geotechnical and Geoenvironmental Engineering,2006,133(11):591-602.
[7]刘清秉,项伟,崔德山,等.颗粒形状对砂土抗剪强度及桩端阻力影响机制试验研究[J].岩石力学与工程学报,2011,30(2):400-409.LIU Qing-bing,XIANG Wei,CUI De-shan,et al.Experimental study of effect of particle shapes on shear strength of sand and tip resistance of driven piles[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(2):400-409.
[8]CUNDALL P A,STRACK O D L.A discrete numerical model for granular assemblies[J].Geotechnique,1979,29(1):47-65.
[9]ROTHENBURG L,BATHURST R J.Micromechanical features of granular assemblies with planar elliptical particles[J].Geotechnique,1992,42(1):79-95.
[10]NG T T.Particle shape effect on macro-and microbehaviors of monodisperse ellipsoids[J].International Journal for Numerical and Analytical Methods in Geomechanics,2009,33(4):511-527.
[11]ZHOU W,HUANG Y,NG T T,et al.A geometric potential-based contact detection algorithm for egg-shaped particles in discrete element modeling[J].Powder Technology,2018,327:152-162.
[12]MIRGHASEMI A A,ROTHENBURG L,MATYAS E L.Influence of particle shape on engineering properties of assemblies of two-dimensional polygon-shaped particles[J].Geotechnique,2002,52(3):209-217.
[13]ZHOU W,MA G,CHANG X,et al.Influence of particle shape on behavior of rockfill using a three-dimensional deformable DEM[J].Journal of Engineering Mechanics,2013,139(12):1868-1873.
[14]ZHOU W,MA G,CHANG X,et al.Discrete modeling of rockfill materials considering the irregular shaped particles and their crushability[J].Engineering Computations,2015,32(4):1104-1120.
[15]TAPIAS M,ALONSO E E,GILI J.A particle model for rockfill behaviour[J].Geotechnique,2015,65(12):975-994.
[16]XU M,HONG J,SONG E.DEM study on the effect of particle breakage on the macro-and micro-behavior of rockfill sheared along different stress paths[J].Computers and Geotechnics,2017,89:113-127.
[17]ZHOU M,SONG E.A random virtual crack DEM model for creep behavior of rockfill based on the subcritical crack propagation theory[J].Acta Geotechnica,2016,11(4):827-847.
[18]ZHAO Z,SONG E.Particle mechanics modeling of creep behavior of rockfill materials under dry and wet conditions[J].Computers and Geotechnics,2015,68:137-146.
[19]周健,池毓蔚,池永,等.砂土双轴试验的颗粒流模拟[J].岩土工程学报,2000,22(6):701-704.ZHOU Jian,CHI Yu-wei,CHI Yong,et al.Simulation of biaxial test on sand by particle flow code[J].Chinese Journal of Geotechnical Engineering,2000,22(6):701-704.
[20]MATTHEW R K,KATALIN B.Sample size effect in discrete element simulations[C]//The 6th European Solid Mechanics Conference.Budapest:ESMC,2006.
[21]刘海涛,程晓辉.粗粒土尺寸效应的离散元分析[J].岩土力学,2009,30(增刊1):287-292.LIU Hai-tao,CHENG Xiao-hui.Discrete element analysis for size effects of coarse-grained soils[J].Rock and Soil Mechanics,2009,30(Suppl.1):287-292.
[22]EMERIAULT F,CLAQUIN C.Statistical homogenization for assemblies of elliptical grains:effect of the aspect ratio and particle orientation[J].International Journal of Solids and Structures,2004,41(21):5837-5849.
[23]SALOT C,GOTTELAND P,VILLARD P.Influence of relative density on granular materials behavior:DEMsimulations of triaxial tests[J].Granular Matter,2009,11(4):221-236.
[24]MINH N H,CHENG Y P.A DEM investigation of the effect of particle-size distribution on one-dimensional compression[J].Géotechnique,2013,63(1):44-53.
[25]中华人民共和国水利部.GB/T50123―1999土工试验方法标准[S].北京:中国计划出版社,1999.Ministry of Water Resources of the People's Republic of China.GB/T50123―1999 Standard for soil test method[S].Beijing:China Planning Press,1999.
[26]DELUZARCHE R,CAMBOU B,FRY J J.Modeling of rockfill behavior with crushable particles[C]//Numerical Modeling in Micromechanics via Particle Methods,Proceedings of the First International PFC Symposium.Gelsenkirchen:Heinz Konietzky,2002,6(7):219-224.
[27]DONEV A,CONNELLY R,STILLINGER F H,et al.Hypostatic jammed packings of nonspherical hard particles:ellipses and ellipsoids[J].Physical Review EStatistical Nonlinear&Soft Matter Physics,2006,75:051304.
[28]THORNTON C.Numerical simulations of deviatoric shear deformation of granular media[J].Geotechnique,2000,50(1):43-53.
[29]BOLTON M D,NAKATA Y,CHENG Y P.Micro-and macro-mechanical behaviour of DEM crushable materials[J].Geotechnique,2008,58(6):471-480.
[30]SATAKE M.Fabric tensor in granular materials[C]//IUTAM Conference on Deformation and Failure of Granular Materials.Delft:A.A.Balkema,1982:63-68.
[31]MAKSE H A,JOHNSON D L,SCHWARTZ L M.Packing of compressible granular materials[J].Physical Review Letters,2000,84(18):4160.