非饱和土孔隙比与基质吸力关系的通用模型
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摘要
基于土的土–水特征曲线(SWCC)和收缩特征曲线(SSCC)的特点及二者之间的联系,采用三直线的分段SSCC模型及非饱和土的三相比例公式,推导出了反映非饱和土孔隙比与基质吸力关系的通用模型。为了证实所提出模型的可靠性,采用GDS三轴仪进行了一系列吸力平衡试验,并对所提出模型的理论假设进行了验证。试验结果表明:利用该假设并通过吸力平衡下试样的排水量,可以准确地预测饱和试样在某一基质吸力和净围压共同作用下的体积变化量、进气量和总体变,证明了所提出模型的假设是成立的,且假设中的系数u具有明确的物理意义。
A general model is proposed to simulate the dependence of void ratio on matric suction for unsaturated soils. This model can be derived based on(i) the characteristics and the relationship between soil-water characteristic curve(SWCC) and soil shrinkage characteristic curve(SSCC) and(ii) a SSCC formula using a three-segment linear model, and a three-phase basic formula for unsaturated soils. A series of unsaturated tests are conducted by using the triaxial apparatus on a red clay to further verify the theoretical assumption required for the proposed model. Only one parameter u is required in the theoretical assumption and has a clear physical meaning, which can be calibrated using the conventional SWCC tests. Based on the assumption with the amount of drainage of saturated samples at a given suction, the bulk volume change, the amount of the air entry into the soil and the total volumetric strain can be accurately predicted. The validity and application of the assumption are demonstrated by these tests, and hence the proposed assumption-based model is also validated.
A general model is proposed to simulate the dependence of void ratio on matric suction for unsaturated soils. This model can be derived based on(i) the characteristics and the relationship between soil-water characteristic curve(SWCC) and soil shrinkage characteristic curve(SSCC) and(ii) a SSCC formula using a three-segment linear model, and a three-phase basic formula for unsaturated soils. A series of unsaturated tests are conducted by using the triaxial apparatus on a red clay to further verify the theoretical assumption required for the proposed model. Only one parameter u is required in the theoretical assumption and has a clear physical meaning, which can be calibrated using the conventional SWCC tests. Based on the assumption with the amount of drainage of saturated samples at a given suction, the bulk volume change, the amount of the air entry into the soil and the total volumetric strain can be accurately predicted. The validity and application of the assumption are demonstrated by these tests, and hence the proposed assumption-based model is also validated.
引文
[1]孙德安.非饱和土的水力和力学特性及其弹塑性描述[J].岩土力学,2009,30(11):3217-3231.(SUN De-an.Hydro-mechanical behaviours of unsaturated soils andtheir elastoplastic modelling[J].Rock and Soil Mechanics,2009,30(11):3217-3231.(in Chinese))
[2]刘艳,韦昌富,房倩,等.非饱和土水-力本构模型及其隐式积分算法[J].岩土力学,2014,35(2):365-370.(LIU Yan,WEI Chang-fu,FANG Qian,et al.Implicit integration algorithm of a hydro-mechanical coupling constitutive model for unsaturated soils[J].Rock and Soil Mechanics,2014,35(2):365-370.(in Chinese))
[3]周葆春,孔令伟,梁维云,等.压缩过程中非饱和膨胀土体变特征与持水特性的水力耦合效应[J].岩土工程学报,2015,37(4):629-640.(ZHOU Bao-chun,KONG Ling-wei,LIANG Wei-yun,et al.Hydro-mechanical coupling effects on volume change and water retention behaviour of unsaturated expansive soils during compression[J].Chinese Jounal of Geotechnical Engineering,2015,37(4):629-640.(in Chinese))
[4]陈正汉,秦冰.非饱和土的应力状态变量研究[J].岩土力学,2012,33(1):1-11.(CHEN Zheng-han,QIN Bing.On stress state variables of unsaturated soils[J].Rock and Soil Mechanics,2012,33(1):1-11.(in Chinese))
[5]盛岱超,杨超.关于非饱和土本构研究的几个基本规律的探讨[J].岩土工程学报,2012,34(3):438-456.(SHENGDai-chao,YANG Chao.Discussion of fundamental principles in unsaturated soil mechanics[J].Chinese Jounal of Geotechnical Engineering,2012,34(3):438-456.(in Chinese))
[6]徐筱,赵成刚,蔡国庆.区分毛细和吸附作用的非饱和土抗剪强度模型[J].岩土力学,2018,39(6):1001-1007.(XU Xiao,ZHAO Cheng-gang,CAI Guo-qing.Shear strength with capillary and adsorptive mechanisms for unsaturated soils[J].Rock and Soil Mechanics,2018,39(6):1001-1007.(in Chinese))
[7]WHEELER S J,SHARMA R S,BUISSON MS R.Couplingof hydraulic hysteresis and stress-strain behaviour in unsaturatedsoils[J].Géotechnique,2003,53(1):41-54.
[8]叶为民,钱丽鑫,白云,等.由土-水特征曲线预测上海非饱和软土渗透系数[J].岩土工程学报,2005,27(11):1262-1265.(YE Wei-min,QIAN Li-xin,BAI Yun,et al.Predicting coefficient of permeability from soil-water characteristic curve for Shanghai soft soil[J].Chinese Jounal of Geotechnical Engineering,2005,27(11):1262-1265.(in Chinese))
[9]FREDLUND D G,XING A.Equations for the soil-water characteristic curve[J].Canadian Geotechnical Journal,1994,31(4):521-532.
[10]VAN GENUCHTEN M T.A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J].Soil Science Society of America Journal,1980,44(44):892-898.
[11]BROOKS R H,COREY AT.Hydraulic properties of porous media[R].Fort Collins:Colorado State University,1964.
[12]ALONSO E E,GENS A,JOSA A.A constitutive model for partially saturated soils[J].Géotechnique,1990,40(3):405-430.
[13]SUN D A,SHENG D C,CUI H B,et al.A density-dependent elastoplastic hydro-mechanical model for unsaturated compacted soils[J].International Journal for Numerical&Analytical Methods in Geomechanics,2007,31(11):1257-1279.
[14]GALLIPOLI D,WHEELER,S J,KARSTUNEN M.Modelling of variation of degree of saturation in a deformable unsaturated soil[J].Géotechnique,2003,53(1):105-112.
[15]邹维列,张俊峰,王协群.脱湿路径下重塑膨胀土的体变修正与土水特征[J].岩土工程学报,2012,34(12):2213-2219.(ZOU Wei-lie,ZHANG Jun-feng,WANG Xie-qun.Volume change correction and soil-water characteristics of remodeling expansive soil under dehydration path[J].Chinese Journal of Geotechnical Engineering,2012,34(12):2213-2219.(in Chinese))
[16]VANAPALLI S K,PUFAHL D E,FREDLUND D G.The influence of soil structure and stress history on the soil-water characteristic of a compacted till[J].Géotechnique,1999,49(2):143-159.
[17]LU N,DONG Y.Correlationship between soil-shrinkage curve and water-retention characteristics[J].Journal of Geotechnical and Geoenvironmental Engineering,2017,143(9):04017054.
[18]MCGARRY D,MALAFANT K W J.The analysis of volume change in unconfined units of soil[J].Soil Science Society of America Journal,1987,51(51):290-297.
[19]CORNELIS W M,CORLUY J,MEDINA H,et al.Measuring and modelling the soil shrinkage characteristic curve[J].Geoderma,2006,137(1/2):179-191.
[20]BAUMGARTL T,K?CK B.Modelling volume change and mechanical properties with hydraulic models[J].Soil Science Society of America Journal,2004,68(68):57-65.
[21]STANGE C F,HORN R.Modeling the soil water retention curve for conditions of variable porosity[J].Vadose Zone Journal,2005,4(3):602-613.
[22]SALAGER S,El YOUSSOUFI M S,SAIX C.Experimental study of the water retention curve as a function of void ratio[C]//Proceedings of the International Conference Geo-Denver.Denver,2007.
[23]SALAGER S,EI YOUSSOUFI M S,SAIX C.Definition and experimental determination of a soil-water retention surface[J].Canadian Geotechnical Journal,2010,47(6):609-622.
[24]ZHAN L T.Field and laboratory study of an unsaturated expansive soil associated with rain-induced slope instability[D].Hong Kong:The Hong Kong University of Science and Technology,2003.
[2]刘艳,韦昌富,房倩,等.非饱和土水-力本构模型及其隐式积分算法[J].岩土力学,2014,35(2):365-370.(LIU Yan,WEI Chang-fu,FANG Qian,et al.Implicit integration algorithm of a hydro-mechanical coupling constitutive model for unsaturated soils[J].Rock and Soil Mechanics,2014,35(2):365-370.(in Chinese))
[3]周葆春,孔令伟,梁维云,等.压缩过程中非饱和膨胀土体变特征与持水特性的水力耦合效应[J].岩土工程学报,2015,37(4):629-640.(ZHOU Bao-chun,KONG Ling-wei,LIANG Wei-yun,et al.Hydro-mechanical coupling effects on volume change and water retention behaviour of unsaturated expansive soils during compression[J].Chinese Jounal of Geotechnical Engineering,2015,37(4):629-640.(in Chinese))
[4]陈正汉,秦冰.非饱和土的应力状态变量研究[J].岩土力学,2012,33(1):1-11.(CHEN Zheng-han,QIN Bing.On stress state variables of unsaturated soils[J].Rock and Soil Mechanics,2012,33(1):1-11.(in Chinese))
[5]盛岱超,杨超.关于非饱和土本构研究的几个基本规律的探讨[J].岩土工程学报,2012,34(3):438-456.(SHENGDai-chao,YANG Chao.Discussion of fundamental principles in unsaturated soil mechanics[J].Chinese Jounal of Geotechnical Engineering,2012,34(3):438-456.(in Chinese))
[6]徐筱,赵成刚,蔡国庆.区分毛细和吸附作用的非饱和土抗剪强度模型[J].岩土力学,2018,39(6):1001-1007.(XU Xiao,ZHAO Cheng-gang,CAI Guo-qing.Shear strength with capillary and adsorptive mechanisms for unsaturated soils[J].Rock and Soil Mechanics,2018,39(6):1001-1007.(in Chinese))
[7]WHEELER S J,SHARMA R S,BUISSON MS R.Couplingof hydraulic hysteresis and stress-strain behaviour in unsaturatedsoils[J].Géotechnique,2003,53(1):41-54.
[8]叶为民,钱丽鑫,白云,等.由土-水特征曲线预测上海非饱和软土渗透系数[J].岩土工程学报,2005,27(11):1262-1265.(YE Wei-min,QIAN Li-xin,BAI Yun,et al.Predicting coefficient of permeability from soil-water characteristic curve for Shanghai soft soil[J].Chinese Jounal of Geotechnical Engineering,2005,27(11):1262-1265.(in Chinese))
[9]FREDLUND D G,XING A.Equations for the soil-water characteristic curve[J].Canadian Geotechnical Journal,1994,31(4):521-532.
[10]VAN GENUCHTEN M T.A closed-form equation for predicting the hydraulic conductivity of unsaturated soils[J].Soil Science Society of America Journal,1980,44(44):892-898.
[11]BROOKS R H,COREY AT.Hydraulic properties of porous media[R].Fort Collins:Colorado State University,1964.
[12]ALONSO E E,GENS A,JOSA A.A constitutive model for partially saturated soils[J].Géotechnique,1990,40(3):405-430.
[13]SUN D A,SHENG D C,CUI H B,et al.A density-dependent elastoplastic hydro-mechanical model for unsaturated compacted soils[J].International Journal for Numerical&Analytical Methods in Geomechanics,2007,31(11):1257-1279.
[14]GALLIPOLI D,WHEELER,S J,KARSTUNEN M.Modelling of variation of degree of saturation in a deformable unsaturated soil[J].Géotechnique,2003,53(1):105-112.
[15]邹维列,张俊峰,王协群.脱湿路径下重塑膨胀土的体变修正与土水特征[J].岩土工程学报,2012,34(12):2213-2219.(ZOU Wei-lie,ZHANG Jun-feng,WANG Xie-qun.Volume change correction and soil-water characteristics of remodeling expansive soil under dehydration path[J].Chinese Journal of Geotechnical Engineering,2012,34(12):2213-2219.(in Chinese))
[16]VANAPALLI S K,PUFAHL D E,FREDLUND D G.The influence of soil structure and stress history on the soil-water characteristic of a compacted till[J].Géotechnique,1999,49(2):143-159.
[17]LU N,DONG Y.Correlationship between soil-shrinkage curve and water-retention characteristics[J].Journal of Geotechnical and Geoenvironmental Engineering,2017,143(9):04017054.
[18]MCGARRY D,MALAFANT K W J.The analysis of volume change in unconfined units of soil[J].Soil Science Society of America Journal,1987,51(51):290-297.
[19]CORNELIS W M,CORLUY J,MEDINA H,et al.Measuring and modelling the soil shrinkage characteristic curve[J].Geoderma,2006,137(1/2):179-191.
[20]BAUMGARTL T,K?CK B.Modelling volume change and mechanical properties with hydraulic models[J].Soil Science Society of America Journal,2004,68(68):57-65.
[21]STANGE C F,HORN R.Modeling the soil water retention curve for conditions of variable porosity[J].Vadose Zone Journal,2005,4(3):602-613.
[22]SALAGER S,El YOUSSOUFI M S,SAIX C.Experimental study of the water retention curve as a function of void ratio[C]//Proceedings of the International Conference Geo-Denver.Denver,2007.
[23]SALAGER S,EI YOUSSOUFI M S,SAIX C.Definition and experimental determination of a soil-water retention surface[J].Canadian Geotechnical Journal,2010,47(6):609-622.
[24]ZHAN L T.Field and laboratory study of an unsaturated expansive soil associated with rain-induced slope instability[D].Hong Kong:The Hong Kong University of Science and Technology,2003.