A microstructure-dependent hydro-mechanical coupled constitutive model for unsaturated soils
CAI Guo-qing1,2, WANG Ya-nan2, ZHOU An-nan3, ZHAO Cheng-gang1,2
1. Key Laboratory of Urban Underground Engineering of Ministry of Education, Beijing Jiaotong University, Beijing 100044, China; 2. School of Civil Engineering and Architecture, Beijing Jiaotong University, Beijing 100044, China; 3. School of Transportation Science and Engineering, Beihang University, Beijing 100191, China;
Abstract:Stress and hydraulic paths significantly affect the microstructure of unsaturated soil. On the other hand, different pore types and structures also have different impacts on mechanical and hydraulic behavior of soils with double-pore structures such as expansive soils and compacted soils. Based on the hydro-mechanical coupled constitutive model developed by Wheeler (GCM), the effective degree of saturation considering the different effects of macro and micro pores on the hydro-mechanical characteristics is introduced into the Bishop effective stress equation to take the influence of pore structure into account. On the basis of the effective degree of saturation, a microstructure-dependent hydro-mechanical coupled constitutive model for unsaturated soils is then proposed. The performance of the model is verified by various experimental data of isotropic compression tests and the predictions match the observations well, indicating the validity of the proposed model.
蔡国庆, 王亚南, 周安楠, 赵成刚. 考虑微观孔隙结构的非饱和土水-力耦合本构模型[J]. 岩土工程学报, 2018, 40(4): 618-624.
CAI Guo-qing, WANG Ya-nan, ZHOU An-nan, ZHAO Cheng-gang. A microstructure-dependent hydro-mechanical coupled constitutive model for unsaturated soils. Chinese J. Geot. Eng., 2018, 40(4): 618-624.
[1] ALONSO E E, GENS A, JOSA A.A constitutive model for partially saturated soil[J]. Géotechnique, 1990, 40(3): 405-430. [2] 赵成刚, 蔡国庆. 非饱和土广义有效应力原理[J]. 岩土力学, 2009, 30(11): 3232-3236. (ZHAO Cheng-gang, CAI Guo-qing.Principle of generalized effective stress for unsaturated soils[J]. Rock and Soil Mechanics, 2009, 30(11): 3232-3236. (in Chinese)) [3] 陈正汉. 非饱和土与特殊土力学的基本理论研究[J]. 岩土工程学报, 2014, 36(2): 201-272. (CHEN Zheng-han.On basic theories of unsaturated soils and special soils[J]. Chinese Journal of Geotechnical Engineering, 2014, 36(2): 201-272. (in Chinese)) [4] 蔡国庆, 盛岱超, 周安楠. 考虑初始孔隙比影响的非饱和土相对渗透系数方程[J]. 岩土工程学报, 2014, 36(5): 827-835. (CAI Guo-qing, SHENG Dai-chao, ZHOU An-nan.Approach for predicting the relative coefficient of permeability of unsaturated soils with different initial void ratios[J]. Chinese Journal of Geotechnical Engineering, 2014, 36(5): .827-835. (in Chinese)) [5] SHENG D, FREDLUND D G, GENS A.A new modelling approach for unsaturated soils using independent stress variables[J]. Canadian Geotechnical Journal, 2008, 45(4): 511-534 [6] WHEELER S J, SHARMA R J, BUISSON M S R. Coupling of hydraulic hysteresis and strss-strain behaviour in unsaturated soils[J]. Géotechnique, 2003, 53(1): 41-54. [7] MARTI L C, SANCHEZ M, WHEELER S J.Formulation of a three-dimensional constitutive model for unsaturated soils incorporating mechanical-water retention couplings[J]. International Journal for Numerical and Analytical Methods in Geomechanics, 2013, 37(17): 3008-3035. [8] 陈正汉, 周海清, FREDLUND D G, 等. 非饱和土的非线性模型及其应用[J]. 岩土工程学报,1999, 21(5): 603-608. (CHEN Zheng-han, ZHOU Han-qing, FREDLUND D G, et al.Nonlinear model for unsaturated soils and its application[J]. Chinese Journal of Geotechnical Engineering, 1999, 21(5): 603-608. (in Chinese)) [9] 缪林昌. 非饱和土的本构模型研究[J]. 岩土力学, 2007, 28(5): 855-860. (MIAO Lin-chang.Research of constitutive model of unsaturated soils[J]. Rock and Soil Mechanics, 2007, 28(5): 855-860. (in Chinese)) [10] 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 and their elastoplastic modelling[J]. Rock and Soil Mechanics, 2009, 30(11): 3217-3231. (in Chinese)) [11] TANAKA H, SHIWAKOTI D R, OMUKAI N, et al.Pore size distribution of clayey soils measured by mercury intrusion porosimetry and its relation to hydraulic conductivity[J]. Soils and Foundations, 2003, 43(6): 63-73. [12] HOFFMANN C, ALONSO E E, ROMERO E.Hydro-mechanical behaviour of bentonite pellet mixtures[J]. Physics and Chemistry of The Earth, 2007, 32(8—14): 832-849. [13] ALONSO E E, ROMERO E, HOFFMANN C.Hydromechanical behaviour of compacted granular expansive mixtures: experimental and constitutive study[J]. Géotechnique, 2011, 61(4): 329-344. [14] NOWAMOOZ H, MASROURI F.Suction variations and soil fabric of swelling compacted soils[J]. Journal of Rock Mechanics and Geotechnical Engineering, 2010, 2: 129-134. [15] DIAMOND S.Pore size distributions in clays[J] .Clays and Clay Minerals, 1970, 18(1): 7-23. [16] 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. [17] SIVAKUMAR V.A critical state framework for unsaturated soil[D]. Sheffield: University of Sheffield, 1993. [18] CHEN R.Experimental study and constitutive modelling of stress-dependent coupled hydraulic hysteresis and mechanical behaviour of an unsaturated soil[D]. Hong Kong: The Hong Kong University of Science and Technology, 2003.