陈宇龙等：不同应力状态下孔隙结构特征对土一水特征曲线的影响 ·153· 1000 [2]Oberg A L,Sallfors G.Determination of shear strength parameters 1=-2.475x+1213.3 of unsaturated silts and sands based on the water retention curve. R2=0.9879 800 Geotech Test J.1997,20(1):40 [3]Huang S Y,Barbour S L,Fredlund DG.Development and verifi- 600 cation of a coefficient of permeability function for a deformable un- saturated soil.Can Geotech /1998,35(3):411 400 [4]Lim P C,Barbour S L,Fredlund D G.The influence of degree of 卸载 saturation on the coefficient of aqueous diffusion.Can Geotech / 200 1998,35(5):811 [5]Gallage C.Kodikara J.Uchimura T.Laboratory measurement of hydraulic conductivity functions of two unsaturated sandy soils dur- 100 200 300 固结压力Pa ing drying and wetting processes.Soils Found,2013,53(3): 417 图11滞后程度与固结压力的关系曲线 [6] Ng C WW,Pang Y W.Influence of stress state on soil-water Fig.11 Relationship between consolidation pressure and hysteresis characteristics and slope stability.J Geotech Geoenviron Eng 隙不会造成影响.Rostami等2]发现固结压力还会导 2000,126(2):157 致连接孔隙的喉道缩小.张先伟等[2-)利用扫描电镜 [7]Tan Y Z.Hu X J.Yu B.et al.Water retention properties and mesomechanism of silt under consolidation effect.Rock Soil Mech, 对原状样和不同固结压力下土样进行观察，发现土在 2013.34(11):3077 压缩过程中，颗粒排列更加有序，孔隙大小趋向均一 (谈云志，胡新江，喻波，等.固结作用下粉土的持水性能与 化，形状从原状土的多边形转化到稳定状的三角形或 细观机制研究.岩土力学，2013,34(11)：3077) 扁圆形.土粒结构主要呈封闭式片架-镶嵌结构，结构 [8]Tavakoli Dastjerdi M H,Habibagahi G,Nikooee E.Effect of con- 中存在大量孤立孔隙，连通性较差.周建等[]借助扫 fining stress on soil water retention curve and its impact on the 描电镜对固结前后的淤泥质软黏土进行分析，利用微 shear strength of unsaturated soils.Vadose Zone J,2014,13(5): 观结构参数（孔隙度分维值、孔隙概率嫡和平均形状 [9]Irfan M,Uchimura T.Modified triaxial apparatus for determina- 系数)表征孔隙特征与固结压力的对应关系，得到以 tion of elastic wave velocities during infiltration tests on unsaturat- 下结论：固结压力的作用使得颗粒不断地移动和转动， ed soils.KSCE J Civ Eng,2016,20(1):197 逐渐向稳定结构调整，孔隙排列的有序性和定向性增 [10]Pham H Q.A Volume-Mass Constitutire Model for Unsaturated 强，孔隙向着均一化方向发展，孔隙形状逐渐圆滑，孔 Soils Dissertation].Saskatchewan:University of Saskatchewan, 隙结构复杂程度降低 2005 对于同种土样，即使具有相同的孔隙比，但不同试 [11]Chen Z Y,Zhou JX,Wang HJ,et al.Soil Mechanics.Beijing: Tsinghua University Press,1994 样制备方法等因素造成的孔隙结构特征的不同也有可 (陈仲颐，周景星，王洪瑾，等.土力学.北京：清华大学出 能导致不同的土-水特征曲线. 版社，1994) 4结论 [12]Hu X P,Zhao Z H,Ni X W.Influence of stress state on soil- water characteristic curve.Hohai Unir Nat Sci,2013,41(2): 固结压力和基质吸力均能使土体收缩变形.固结 150 压力越大，土颗粒就越紧密，孔隙比越小，孔隙尺寸和 (胡孝彭，赵仲辉，倪晓雯.应力状态对土-水特征曲线的影 数量越小，饱和含水率越低，且渗透性越差，表现出较 响规律.河海大学学报（自然科学版），2013,41(2)：150) [13]Miller C J,Yesiller N,Yaldo K,et al.Impact of soil type and 好的持水能力，空气难以进入土体，土体排水困难，导 compaction conditions on soil water characteristic.J Geotech 致进气值增大.土-水特征曲线与孔隙结构特征的关 Geoenviron Eng,2002.128(9):733 系紧密，与应力状态无直接关系.固结压力对土-水特 [14]Hu R,Chen Y F,Liu HH,et al.A water retention curve and 征曲线的影响是通过改变孔隙结构特征来实现的，只 unsaturated hydraulic conductivity model for deformable soils: 要具有相近的孔隙结构特征，即使应力状态不同，其 consideration of the change in pore-size distribution. Geotechnique,2013,63(16):1389 土-水特征曲线仍然相近.高固结压力对应的滞后特 [15]Zhou A N,Sheng D C,Carter J P.Modelling the effect of initial 性较小 density on soil-water characteristic curves.Geotechnique,2012, 62(8):669 参考文献 [16]Fleureau J M,Verbrugge J C,Huergo PJ,et al.Aspects of the [1]Fredlund D G.Xing A Q.Fredlund M D.et al.The relationship behaviour of compacted clayey soils on drying and wetting paths. of the unsaturated soil shear to the soil-water characteristic curve. Can Geotech J.2002,39(6):1341 Can Geotech J,1996,33(3):440 [17]Shen Z J.Generalized suction and unified deformation theory for陈宇龙等: 不同应力状态下孔隙结构特征对土鄄鄄水特征曲线的影响 图 11 滞后程度与固结压力的关系曲线 Fig. 11 Relationship between consolidation pressure and hysteresis 隙不会造成影响. Rostami 等[27] 发现固结压力还会导 致连接孔隙的喉道缩小. 张先伟等[28鄄鄄29]利用扫描电镜 对原状样和不同固结压力下土样进行观察,发现土在 压缩过程中,颗粒排列更加有序,孔隙大小趋向均一 化,形状从原状土的多边形转化到稳定状的三角形或 扁圆形. 土粒结构主要呈封闭式片架鄄鄄镶嵌结构,结构 中存在大量孤立孔隙,连通性较差. 周建等[30] 借助扫 描电镜对固结前后的淤泥质软黏土进行分析,利用微 观结构参数(孔隙度分维值、孔隙概率熵和平均形状 系数)表征孔隙特征与固结压力的对应关系,得到以 下结论:固结压力的作用使得颗粒不断地移动和转动, 逐渐向稳定结构调整,孔隙排列的有序性和定向性增 强,孔隙向着均一化方向发展,孔隙形状逐渐圆滑,孔 隙结构复杂程度降低. 对于同种土样,即使具有相同的孔隙比,但不同试 样制备方法等因素造成的孔隙结构特征的不同也有可 能导致不同的土鄄鄄水特征曲线. 4 结论 固结压力和基质吸力均能使土体收缩变形. 固结 压力越大,土颗粒就越紧密,孔隙比越小,孔隙尺寸和 数量越小,饱和含水率越低,且渗透性越差,表现出较 好的持水能力,空气难以进入土体,土体排水困难,导 致进气值增大. 土鄄鄄 水特征曲线与孔隙结构特征的关 系紧密,与应力状态无直接关系. 固结压力对土鄄鄄水特 征曲线的影响是通过改变孔隙结构特征来实现的,只 要具有相近的孔隙结构特征,即使应力状态不同,其 土鄄鄄水特征曲线仍然相近. 高固结压力对应的滞后特 性较小. 参 考 文 献 [1] Fredlund D G, Xing A Q, Fredlund M D, et al. The relationship of the unsaturated soil shear to the soil鄄鄄water characteristic curve. Can Geotech J, 1996, 33(3): 440 [2] 魻berg A L, S覿llfors G. Determination of shear strength parameters of unsaturated silts and sands based on the water retention curve. Geotech Test J, 1997, 20(1): 40 [3] Huang S Y, Barbour S L, Fredlund D G. Development and verifi鄄 cation of a coefficient of permeability function for a deformable un鄄 saturated soil. Can Geotech J, 1998, 35(3): 411 [4] Lim P C, Barbour S L, Fredlund D G. The influence of degree of saturation on the coefficient of aqueous diffusion. Can Geotech J, 1998, 35(5): 811 [5] Gallage C, Kodikara J, Uchimura T. Laboratory measurement of hydraulic conductivity functions of two unsaturated sandy soils dur鄄 ing drying and wetting processes. Soils Found, 2013, 53 (3 ): 417 [6] Ng C W W, Pang Y W. Influence of stress state on soil鄄鄄 water characteristics and slope stability. J Geotech Geoenviron Eng, 2000, 126(2): 157 [7] Tan Y Z, Hu X J, Yu B, et al. Water retention properties and mesomechanism of silt under consolidation effect. Rock Soil Mech, 2013, 34(11): 3077 (谈云志, 胡新江, 喻波, 等. 固结作用下粉土的持水性能与 细观机制研究. 岩土力学, 2013, 34(11): 3077) [8] Tavakoli Dastjerdi M H, Habibagahi G, Nikooee E. Effect of con鄄 fining stress on soil water retention curve and its impact on the shear strength of unsaturated soils. Vadose Zone J, 2014, 13(5): 1 [9] Irfan M, Uchimura T. Modified triaxial apparatus for determina鄄 tion of elastic wave velocities during infiltration tests on unsaturat鄄 ed soils. KSCE J Civ Eng, 2016, 20(1): 197 [10] Pham H Q. A Volume鄄鄄 Mass Constitutive Model for Unsaturated Soils [Dissertation]. Saskatchewan: University of Saskatchewan, 2005 [11] Chen Z Y, Zhou J X, Wang H J, et al. Soil Mechanics. Beijing: Tsinghua University Press, 1994 (陈仲颐, 周景星, 王洪瑾, 等. 土力学. 北京: 清华大学出 版社, 1994) [12] Hu X P, Zhao Z H, Ni X W. Influence of stress state on soil鄄鄄 water characteristic curve. J Hohai Univ Nat Sci, 2013, 41(2): 150 (胡孝彭, 赵仲辉, 倪晓雯. 应力状态对土鄄鄄水特征曲线的影 响规律. 河海大学学报(自然科学版), 2013, 41(2): 150) [13] Miller C J, Yesiller N, Yaldo K, et al. Impact of soil type and compaction conditions on soil water characteristic. J Geotech Geoenviron Eng, 2002, 128(9): 733 [14] Hu R, Chen Y F, Liu H H, et al. A water retention curve and unsaturated hydraulic conductivity model for deformable soils: consideration of the change in pore鄄size distribution. G佴otechnique, 2013, 63(16): 1389 [15] Zhou A N, Sheng D C, Carter J P. Modelling the effect of initial density on soil鄄鄄water characteristic curves. G佴otechnique, 2012, 62(8): 669 [16] Fleureau J M, Verbrugge J C, Huergo P J, et al. Aspects of the behaviour of compacted clayey soils on drying and wetting paths. Can Geotech J, 2002, 39(6): 1341 [17] Shen Z J. Generalized suction and unified deformation theory for ·153·