An effective stress equation for unsaturated silt considering the microstructure of pore water and its verification
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摘要:
有效应力参数的合理确定是非饱和土有效应力研究的重要内容。然而，现有的有效应力参数未能较好地考虑孔隙水的微观赋存形态对有效应力的影响。为此，分析了孔隙水的微观赋存形态，明确了孔隙水可分为收缩膜、吸附水和毛细水，建立了非饱和粉土的扩展三相孔隙介质模型，即孔隙气、毛细水和广义土骨架。基于该模型，采用分相平衡分析法，推导了非饱和粉土的有效应力方程，该方程通过采用毛细水有效饱和度合理地考虑了毛细水对有效应力的影响。依据推导的有效应力方程，提出了非饱和粉土的抗剪强度公式。采用5种不同围压下重塑非饱和粉质黏土试验数据验证了提出的公式。结果表明：与现有的抗剪强度公式相比，本次提出的公式更好地预测了重塑非饱和粉质黏土的抗剪强度随基质吸力的变化规律。因此，运用提出的抗剪强度公式评价非饱和土边坡稳定性、地基承载力和挡土墙稳定性将会取得更好的效果。
Abstract:Accurate determination of the effective stress coefficient is an important thing in the study of the effective stress of unsaturated soils. However, the existing effective stress coefficients have not well considered the effect of the microscopic occurrence of pore water in unsaturated soils on the effective stress. For this reason, the microscopic occurrence of pore water is analyzed firstly. It is recognized that the pore water in unsaturated soils can be divided into the contractile skin, adsorbed water and capillary water, and an extended three-phase porous medium model of unsaturated silt is established, considering the pore air, capillary water, and generalized soil skeleton. Based on the established model, an effective stress equation for unsaturated silt is derived by using an independent phase balance approach. The equation reasonably considers the influences of the capillary water on the effective stress by adopting a coefficient (i.e., the effective saturation of capillary water). In light of the derived effective stress equation, a shear strength equation for unsaturated silt is proposed. Finally, the proposed shear strength equation is verified by the experimental data on a reconstituted unsaturated silty clay under five different net confining pressures. The results show that compared with the existing two shear strength equations, the proposed equation better predicts the variation of the shear strength of the reconstituted unsaturated silty clay with matric suction. Therefore, under the unsaturated conditions, using the proposed shear strength formula to evaluate the stability of slopes, the bearing capacity of foundation, and the stability of retaining wall will achieve better results.
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Key words:
- unsaturated silt /
- pore water /
- microscopic occurrence /
- effective stress /
- shear strength /
- SWRC
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[1] 邵龙潭, 郭晓霞. 有效应力新解[M]. 北京: 中国水利水电出版社, 2014
SHAO Longtan, GUO Xiaoxia. New interpretation of effective stress [M]. Beijing: China Water & Power Press, 2014. (in Chinese)
[2] 陈嘉伟, 高游, 付俊杰, 等. 不同类型黏土的强度特性及其预测[J]. 水文地质工程地质,2020,47(3):101 − 106. [CHEN Jiawei, GAO You, FU Junjie, et al. Strength of different clayey soils and its prediction[J]. Hydrogeology & Engineering Geology,2020,47(3):101 − 106. (in Chinese with English abstract)
CHEN Jiawei, GAO You, FU Junjie, et al. Strength of different clayey soils and its prediction [J]. Hydrogeology & Engineering Geology, 2020, 47(3): 101-106. (in Chinese with English abstract)
[3] 邵龙潭, 覃亚龙, 郭晓霞, 等. 非饱和土有效应力公式验证[J]. 地下空间与工程学报,2018,14(6):1476 − 1483. [SHAO Longtan, QIN Yalong, GUO Xiaoxia, et al. The validation of the effective stress principle of unsaturated soils[J]. Chinese Journal of Underground Space and Engineering,2018,14(6):1476 − 1483. (in Chinese with English abstract)
SHAO Longtan, QIN Yalong, GUO Xiaoxia, et al. The validation of the effective stress principle of unsaturated soils [J]. Chinese Journal of Underground Space and Engineering, 2018, 14(6): 1476-1483. (in Chinese with English abstract)
[4] 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. [SHENG Daichao, YANG Chao. Discussion of fundamental principles in unsaturated soil mechanics[J]. Chinese Journal of Geotechnical Engineering,2012,34(3):438 − 456. (in Chinese with English abstract)
SHENG Daichao, YANG Chao. Discussion of fundamental principles in unsaturated soil mechanics [J]. Chinese Journal of Geotechnical Engineering, 2012, 34(3): 438-456. (in Chinese with English abstract)
[5] 韩博文, 蔡国庆, 李舰, 等. 考虑颗粒黏结效应的非饱和土水–力耦合边界面模型[J]. 岩土工程学报,2020,42(11):2059 − 2068. [HAN Bowen, CAI Guoqing, LI Jian, et al. Hydro-mechanical coupling bounding surface model for unsaturated soils considering bonding effect of particles[J]. Chinese Journal of Geotechnical Engineering,2020,42(11):2059 − 2068. (in Chinese with English abstract)
HAN Bowen, CAI Guoqing, LI Jian, et al. Hydro-mechanical coupling bounding surface model for unsaturated soils considering bonding effect of particles [J]. Chinese Journal of Geotechnical Engineering, 2020, 42(11): 2059-2068. (in Chinese with English abstract)
[6] 饶鸿, 王金淑, 赵志明, 等. 基于有限元软件自定义本构模型的膨胀土边坡降雨入渗分析[J]. 水文地质工程地质,2021,48(1):154 − 162. [RAO Hong, WANG Jinshu, ZHAO Zhiming, et al. An analysis of rainfall infiltration of expansive soil slope based on the finite element software custom constitutive model[J]. Hydrogeology & Engineering Geology,2021,48(1):154 − 162. (in Chinese with English abstract)
RAO Hong, WANG Jinshu, ZHAO Zhiming, et al. An analysis of rainfall infiltration of expansive soil slope based on the finite element software custom constitutive model [J]. Hydrogeology & Engineering Geology, 2021, 48(1): 154-162. (in Chinese with English abstract)
[7] 徐永福. 膨胀土地基承载力研究[J]. 岩石力学与工程学报,2000,19(3):387 − 390. [XU Yongfu. Study on bearing capacity of expansive soil basement[J]. Chinese Journal of Rock Mechanics and Engineering,2000,19(3):387 − 390. (in Chinese with English abstract) doi: 10.3321/j.issn:1000-6915.2000.03.030
XU Yongfu. Study on bearing capacity of expansive soil basement [J]. Chinese Journal of Rock Mechanics and Engineering, 2000, 19(3): 387-390. (in Chinese with English abstract) doi: 10.3321/j.issn:1000-6915.2000.03.030
[8] 汪丁建, 童龙云, 邱岳峰. 降雨入渗条件下非饱和土朗肯土压力分析[J]. 岩土力学,2013,34(11):3192 − 3196. [WANG Dingjian, TONG Longyun, QIU Yuefeng. Rankine's earth pressure analysis of unsaturated soil under condition of rainfall infiltration[J]. Rock and Soil Mechanics,2013,34(11):3192 − 3196. (in Chinese with English abstract)
WANG Dingjian, TONG Longyun, QIU Yuefeng. Rankine's earth pressure analysis of unsaturated soil under condition of rainfall infiltration [J]. Rock and Soil Mechanics, 2013, 34(11): 3192-3196. (in Chinese with English abstract)
[9] BISHOP A W. The principle of effective stress[J]. Teknisk Ukeblad,1959,106(39):859 − 863.
[10] ÖBERG A L, SÄLLFORS G. Determination of shear strength parameters of unsaturated silts and sands based on the water retention curve[J]. Geotechnical Testing Journal,1997,20(1):40 − 48. doi: 10.1520/GTJ11419J
[11] LU N, LIKOS W J. Suction stress characteristic curve for unsaturated soil[J]. Journal of Geotechnical and Geoenvironmental Engineering,2006,132(2):131 − 142. doi: 10.1061/(ASCE)1090-0241(2006)132:2(131)
[12] VANAPALLI S K, FREDLUND D G, PUFAHL D E, et al. Model for the prediction of shear strength with respect to soil suction[J]. Canadian Geotechnical Journal,1996,33(3):379 − 392. doi: 10.1139/t96-060
[13] ALONSO E E, PEREIRA J M, VAUNAT J, et al. A microstructurally based effective stress for unsaturated soils[J]. Géotechnique,2010,60(12):913 − 925.
[14] ZHOU A, HUANG R, SHENG D. Capillary water retention curve and shear strength of unsaturated soils[J]. Canadian Geotechnical Journal,2016,53(6):974 − 987. doi: 10.1139/cgj-2015-0322
[15] MITCHELL J K, SOGA K. Fundamentals of soil behavior [M]. 3th ed. Hoboken: John Wiley & Sons Inc, 2005.
[16] WANG J P, LAMBERT P, DE KOCK T, et al. Investigation of the effect of specific interfacial area on strength of unsaturated granular materials by X-ray tomography[J]. Acta Geotechnica,2019,14(5):1545 − 1559. doi: 10.1007/s11440-019-00765-2
[17] LOUREN O S D N, GALLIPOLI D, AUGARDE C E, et al. Formation and evolution of water menisci in unsaturated granular media[J]. Géotechnique,2012,62(3):193 − 199.
[18] FREDLUND D G, RAHARDJO H. Soil mechanics for unsaturated soils [M]. New York: John Wiley & Sons Inc, 1993.
[19] COSTANZA-ROBINSON M S, BRUSSEAU M L. Air-water interfacial areas in unsaturated soils: Evaluation of interfacial domains[J]. Water Resources Research,2002,38(10):13 − 1.
[20] LU N, LIKOS W J. Unsaturated soils mechanics [M]. New Jersey: John Wiley & Sons Inc, 2004.
[21] LU N. Generalized soil water retention equation for adsorption and capillarity[J]. Journal of Geotechnical and Geoenvironmental Engineering,2016,142(10):04016051. doi: 10.1061/(ASCE)GT.1943-5606.0001524
[22] TOLL D G, ALI RAHMAN Z. Critical state shear strength of an unsaturated artificially cemented sand[J]. Géotechnique,2017,67(3):208 − 215.
[23] DHOPATKAR N, DEFANTE A P, DHINOJWALA A. Ice-like water supports hydration forces and eases sliding friction[J]. Science Advances,2016,2(8):e1600763. doi: 10.1126/sciadv.1600763
[24] JACINTO A C, VILLAR M V, LEDESMA A. Influence of water density on the water-retention curve of expansive clays[J]. Géotechnique,2012,62(8):657 − 667.
[25] GHEZZEHEI T A, OR D. Rheological properties of wet soils and clays under steady and oscillatory stresses[J]. Soil Science Society of America Journal,2001,65(3):624 − 637. doi: 10.2136/sssaj2001.653624x
[26] BAYUK I O, AMMERMAN M, CHESNOKOV E M. Upscaling of elastic properties of anisotropic sedimentary rocks[J]. Geophysical Journal International,2008,172(2):842 − 860. doi: 10.1111/j.1365-246X.2007.03645.x
[27] GAO Y, SUN D A, ZHOU A, et al. Predicting shear strength of unsaturated soils over wide suction range[J]. International Journal of Geomechanics,2020,20(2):04019175. doi: 10.1061/(ASCE)GM.1943-5622.0001555
[28] SHENG D, ZHOU A, FREDLUND D G. Shear strength criteria for unsaturated soils[J]. Geotechnical and Geological Engineering,2011,29(2):145 − 159. doi: 10.1007/s10706-009-9276-x
[29] CUNNINGHAM M R, RIDLEY A M, DINEEN K, et al. The mechanical behaviour of a reconstituted unsaturated silty clay[J]. Géotechnique,2003,53(2):183 − 194.
[30] CAMPBELL G S, SHIOZAWA S. Prediction of hydraulic properties of soils using particle-size distribution and bulk density data [C]//VAN GENUCHTEN M T, LEIJ R J, LUND L J. International Workshop on Indirect Methods for Estimating the Hydraulic Properties of Unsaturated Soils. University of California, Riverside. 1992: 317 − 328.
[31] LEBEAU M, KONRAD J-M. A new capillary and thin film flow model for predicting the hydraulic conductivity of unsaturated porous media[J]. Water Resources Research,2010,46(12):W12554.
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