饱和黏土平均粒间应力的确定方法
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摘要
粒间作用力是控制土体强度和压缩特性的重要参量,但由于黏土中矿物颗粒与孔隙水间存在复杂的物理化学作用,其粒间应力及其变化规律一直无法确定。对泥浆重塑样在不同水化学条件下进行了一系列黏土一维侧限压缩试验,探讨不同浓度的NaCl溶液对饱和黏土压缩过程的影响,并确定土中粒间应力的大小及其变化规律。结果表明:同一级固结应力作用下,随替换溶液浓度的增加渗透固结变形量增大;对于相同浓度的孔隙溶液,固结应力越大,相应的渗透固结变形量越小。根据太沙基有效应力原理,提出了一种利用渗透固结变形来计算平均粒间应力的方法,在此基础上确立了粒间应力(或广义渗透压力)相对变化量与浓度和孔隙比之间的定量关系。该研究提供了一种简单有效的确定饱和黏土粒间应力的方法,为今后校正和验证多场耦合下土本构理论模型奠定基础。
The shear strength and compressibility of soils are largely controlled by intergranular interactions. For clayey soils, however,the intergranular stresses remain elusive experimentally due to the complex physicochemical interactions between the clay minerals and pore water. To explore the effect of Na Cl solution with different concentration on clay compression and to determine the intergranular stresses, a series of oedometer experiments was performed on the remolded samples prepared from a slurry mud. It is shown that at the same vertical stress, the deformation during osmotic consolidation increases with pore water concentration, and at the same concentration, the deformation during osmotic consolidation decreases as the vertical stress increases. Based on Terzaghi's effective stress principle, the average intergranular stress is calculated based on the osmosis-induced deformation, and the dependence of intergranular stress(or the generalized osmotic pressure) variation on the pore water concentration and void ratio(i.e., dry density)is determined. This paper provides a simple and yet effective approach to determine the intergranular stresses for clayey soils, which is helpful in calibrating the constitutive model of soils with multiple coupled physicochemical processes.
The shear strength and compressibility of soils are largely controlled by intergranular interactions. For clayey soils, however,the intergranular stresses remain elusive experimentally due to the complex physicochemical interactions between the clay minerals and pore water. To explore the effect of Na Cl solution with different concentration on clay compression and to determine the intergranular stresses, a series of oedometer experiments was performed on the remolded samples prepared from a slurry mud. It is shown that at the same vertical stress, the deformation during osmotic consolidation increases with pore water concentration, and at the same concentration, the deformation during osmotic consolidation decreases as the vertical stress increases. Based on Terzaghi's effective stress principle, the average intergranular stress is calculated based on the osmosis-induced deformation, and the dependence of intergranular stress(or the generalized osmotic pressure) variation on the pore water concentration and void ratio(i.e., dry density)is determined. This paper provides a simple and yet effective approach to determine the intergranular stresses for clayey soils, which is helpful in calibrating the constitutive model of soils with multiple coupled physicochemical processes.
引文
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[25]杨德欢,颜荣涛,韦昌富,等.粉质黏土强度指标的水化学敏感性研究[J].岩土力学,2016,37(12):3529-3536.YANG De-huan,YAN Rong-tao,WEI Chang-fu,et al.Astudy of water chemical sensitivity of strength indices of silty clay[J].Rock and Soil Mechanics,2016,37(12):3529-3536.
[26]师旭超,汪稔,胡元育,等.渗透固结试验装置的研制[J].岩石力学与工程学报,2004,23(22):3891-3895.SHI Xu-chao,WANG Ren,HU Yuan-yu,et al.Development of osmotic oedometer[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(22):3891-3895.
[27]杨德欢.孔隙水溶液对高岭土变形特性的影响机理[D].桂林:桂林理工大学,2016.YANG De-huan.Influencing mechanism of pore water chemistry on volume change behavior of kaolinite[D].Guilin:Guilin University of Technology,2016.
[28]高国瑞.近代土质学[M].北京:科学出版社,2013.GAO Guo-rui.Neoteric soil geotechnology[M].Beijing:Science Press,2013.
[2]HOMAND S,SHAO J F.Mechanical behaviour of a porous chalk and water/chalk interaction.Part I:experimental study[J].Oil&Gas Science and Technology,2000,55(6):591-598.
[3]RISNES R,FLAAGENG O.Mechanical properties of chalk with emphasis on chalk-fluid interactions and micromechanical aspects[J].Oil&Gas Science and Technology,1999,54(6):751-758.
[4]GUTIERREZ M,?INO L E,H?EG K.The effect of fluid content on the mechanical behaviour of fractures in chalk[J].Rock Mechanics and Rock Engineering,2000,33(2):93-117.
[5]张倩.水化学环境变化对多孔介质强度和渗透性的影响[D].青岛:中国海洋大学,2010.ZHANG Qian.Effects of different electrical solutions on strength and permeability of saturated porous[D].Qingdao:Ocean University of China,2010.
[6]汤文,姚志宾,李邵军,等.水化学作用对滑坡滑带土的物理力学特性影响试验研究[J].岩土力学,2016,37(10):2885-2892.TANG Wen,YAO Zhi-bin,LI Shao-jun,et al.Effect of pore water chemistry on physical and mechanical properties of sliding-zone soil:an experimental study[J].Rock and Soil Mechanics,2016,37(10):2885-2892.
[7]FAM M,SANTAMARINA J C.Coupled diffusion-fabric-flow phenomena:an effective stress analysis[J].Canadian Geotechnical Journal,1996,33(3):515-522.
[8]BOLT G H.Physico-chemical analysis of the compressibility of pure clays[J].Géotechnique,1956,6(2):86-93.
[9]MITCHELL J K.Components of pore water pressure and their engineering significance[J].Clays&Clay Minerals,1962,9(1):162-184.
[10]SRIDHARAN A,RAO G V.Mechanisms controlling volume change of saturated clays and the role of the effective stress concept[J].Géotechnique,1973,23(3):359-382.
[11]SRIDHARAN A,JAYADEVA M S.Double layer theory and compressibility of clays[J].Géotechnique,1982,32(2):133-144.
[12]BARBOUR S L,FREDLUND D G.Mechanisms of osmotic flow and volume change in clay soils[J].Canadian Geotechnical Journal,1989,26(4):551-562.
[13]DI MAIO C.Exposure of bentonite to salt solution:osmotic and mechanical effects[J].Geotechnique,1996,46(4):695-707.
[14]THYAGARAJ T,RAO S M.Osmotic swelling and osmotic consolidation behaviour of compacted expansive clay[J].Geotechnical and Geological Engineering,2013,31(2):435-445.
[15]WITTEVEEN P J,FERRARI A,LALOUI L.An experimental and constitutive investigation on the chemo-mechanical behaviour of a clay[J].Geotechnique,2013,63(3):244-255.
[16]XU Y F,XIANG G S,JIANG H,et al.Role of osmotic suction in volume change of clays in salt solution[J].Applied Clay Science,2014,101:354-361.
[17]张彤炜,邓永锋,刘松玉,等.渗透吸力对重塑黏土的压缩和渗透特性影响的试验研究[J].岩土工程学报,2014,36(12):2260-2266.ZHANG Tong-wei,DENG Yong-feng,LIU Song-yu,et al.Experimental investigation of osmotic suction effect on hydro-mechanical behaviour of remolded clay[J].Chinese Journal of Geotechnical Engineering,2014,36(12):2260-2266.
[18]HUECKEL T.Chemo-plasticity of clays subjected to stress and flow of a single contaminant[J].International Journal for Numerical&Analytical Methods in Geomechanics,2015,21(1):43-72.
[19]LORET B,HUECKEL T,GAJO A.Chemo-mechanical coupling in saturated porous media:elastic-plastic behaviour of homoionic expansive clays[J].International Journal of Solids and Structures,2002,39(10):2773-2806.
[20]RAO S M,SHIVANANDA P.Role of osmotic suction in swelling of salt-amended clays[J].Canadian Geotechnical Journal,2005,42(1):307-315.
[21]GON?ALVèS J,ROUSSEAU-GUEUTIN P,MARSILYG D,et al.What is the significance of pore pressure in a saturated shale layer?[J].Water Resources Research,2010,46(4),W04514.
[22]WEI C F.A Theoretical framework for modeling the chemomechanical behavior of unsaturated soils[J].Vadose Zone Journal,2014,13(9):1-21.
[23]MA T T,WEI C F,XIA X L,et al.Constitutive model of unsaturated soils considering the effect of intergranular physicochemical forces[J].Journal of Engineering Mechanics,2016,142(11):04016088.
[24]于海浩,韦昌富,颜荣涛,等.孔隙溶液浓度的变化对黏土强度的影响[J].岩土工程学报,2015,37(3):564-569.YU Hai-hao,WEI Chang-fu,YAN Rong-tao,et al.Effects of pore solution concentrations on shear strength of clay[J].Chinese Journal of Geotechnical Engineering,2015,37(3):564-569.
[25]杨德欢,颜荣涛,韦昌富,等.粉质黏土强度指标的水化学敏感性研究[J].岩土力学,2016,37(12):3529-3536.YANG De-huan,YAN Rong-tao,WEI Chang-fu,et al.Astudy of water chemical sensitivity of strength indices of silty clay[J].Rock and Soil Mechanics,2016,37(12):3529-3536.
[26]师旭超,汪稔,胡元育,等.渗透固结试验装置的研制[J].岩石力学与工程学报,2004,23(22):3891-3895.SHI Xu-chao,WANG Ren,HU Yuan-yu,et al.Development of osmotic oedometer[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(22):3891-3895.
[27]杨德欢.孔隙水溶液对高岭土变形特性的影响机理[D].桂林:桂林理工大学,2016.YANG De-huan.Influencing mechanism of pore water chemistry on volume change behavior of kaolinite[D].Guilin:Guilin University of Technology,2016.
[28]高国瑞.近代土质学[M].北京:科学出版社,2013.GAO Guo-rui.Neoteric soil geotechnology[M].Beijing:Science Press,2013.