饱和超固结黏性土的三剪弹塑性本构模型研究
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摘要
针对饱和超固结黏性土现有下加载面修正剑桥模型中破坏应力比为定值、土体黏聚力为零,以及不能准确反映不同应力状态下土的强度差异这些问题,基于三剪统一强度准则以及应力坐标平移法得到了扩展破坏应力比,其特点是能更好地反映应力状态变化以及土体黏聚力的影响.在此基础上提出了饱和超固结黏性土的三剪弹塑性本构模型,该模型的特点是能描述土体受力时的中间主应力效应,应力区间效应和拉压差影响,同时也能更好地考虑土体黏聚力的影响.基于该模型对ABAQUS软件进行了二次开发,对江西赣南崩岗土常规三轴压缩条件下力学特性作了模拟和试验结果对比,结果表明所提模型能很好地反映土体不同超固结比下的变形、剪胀、孔隙水压力变化特性.并利用其模拟了饱和超固结黏性土在不排水和排水条件下的真三轴和常规三轴压缩试验特性.
The over-consolidated clay exhibits strain softening and dilatancyunder compression.The modified Cam-Claymodel with subloading yield surface can better describe the above soil properties by introducing the failure stress ratio for over-consolidated clay and the void ratio difference for clays between the remolded and the over-consolidated.Due to the definitefailure stress ratio,and without considering soil cohesion,the original model cannot reflect the practical differences of failure properties under different stress states and cohesions for soils.To overcome the shortcomings of the original model,the extended failure stress ratio reflecting different stress states,failure values and soil cohesions is given in this paper for the saturated over-consolidated claybased on the triple-shear unified failure criterion andthe coordinate translation method.The advantage is that the extended failure stress ratio can better represent the practical effects of different stress states on the saturated over-consolidated clay with different cohesions.Accordingto the viewpoint above,a new triple-shear elasto-plastic constitutive model for saturated over-consolidated clay is set up.Features of this proposed constitutive model are that it can describe the effects of the intermediate principal stress,failure difference between tension and compression and different cohesions for soils.In addition,the ABAQUS is secondarydeveloped based on the new constitutive model,and the numerical simulations and experimental results are compared for the collapsed clay in southern JiangxiProvince underconventional triaxialcompression.Calibrations show that the proposed model canbetterrepresentthe mechanical behaviors of deformation,strain softening,dilatancy and pore water pressurefor saturated over-consolidated clay with different over-consolidation ratios(OCRs).The larger OCR indicates the more significant mechanical behaviors of soils.Finally,the soil mechanical properties of saturated over-consolidated clay are simulated with the secondary developed ABAQUS,respectively under true triaxial compression and conventional triaxialcompression in drained and undrained conditions.The numerical simulationresults show that strain softening and dilatancybecome more apparentwith the increasinginfluence coefficient of intermediate principal stress,b,under true triaxial compression.The same phenomena appear with larger confining pressures and OCRs under conventionaltriaxial compression.
The over-consolidated clay exhibits strain softening and dilatancyunder compression.The modified Cam-Claymodel with subloading yield surface can better describe the above soil properties by introducing the failure stress ratio for over-consolidated clay and the void ratio difference for clays between the remolded and the over-consolidated.Due to the definitefailure stress ratio,and without considering soil cohesion,the original model cannot reflect the practical differences of failure properties under different stress states and cohesions for soils.To overcome the shortcomings of the original model,the extended failure stress ratio reflecting different stress states,failure values and soil cohesions is given in this paper for the saturated over-consolidated claybased on the triple-shear unified failure criterion andthe coordinate translation method.The advantage is that the extended failure stress ratio can better represent the practical effects of different stress states on the saturated over-consolidated clay with different cohesions.Accordingto the viewpoint above,a new triple-shear elasto-plastic constitutive model for saturated over-consolidated clay is set up.Features of this proposed constitutive model are that it can describe the effects of the intermediate principal stress,failure difference between tension and compression and different cohesions for soils.In addition,the ABAQUS is secondarydeveloped based on the new constitutive model,and the numerical simulations and experimental results are compared for the collapsed clay in southern JiangxiProvince underconventional triaxialcompression.Calibrations show that the proposed model canbetterrepresentthe mechanical behaviors of deformation,strain softening,dilatancy and pore water pressurefor saturated over-consolidated clay with different over-consolidation ratios(OCRs).The larger OCR indicates the more significant mechanical behaviors of soils.Finally,the soil mechanical properties of saturated over-consolidated clay are simulated with the secondary developed ABAQUS,respectively under true triaxial compression and conventional triaxialcompression in drained and undrained conditions.The numerical simulationresults show that strain softening and dilatancybecome more apparentwith the increasinginfluence coefficient of intermediate principal stress,b,under true triaxial compression.The same phenomena appear with larger confining pressures and OCRs under conventionaltriaxial compression.
引文
[1]Houlsby G T,Wroth C P,Wood D M.Predictions of the results of laboratory tests on a clay using a critical state model[C].In:Proceedings of the International.Symposium Constitutive Laws of Soils,Grenoble Grenoble,1982:99-121.
[2]Mita K A,Dasari G R,Lo K W.Performance of a three-dimensional Hvorslev-modified cam clay model for over-consolidated clay[J].International Journal of Geo-mechanics,ASCE,2004,4(4):296-309.
[3]Yao Y P,Hou W,Zhou A N.UH model:three-dimensional unified hardening model for over-consolidated clays[J].Geo-technique,2009,59(5):451-469.
[4]罗汀,侯伟,姚仰平.考虑渐近状态特性的超固结土本构模型[J].岩土力学,2010,31(3):683-688,694.(Luo T,Hou W,Yao Y P.An asymptotic state constitutive model for over-consolidated clays[J].Rock and Soil Mechanics,2010,31(3):683-688,694.(in Chinese))
[5]Dafalias Y F.Bounding surface plasticity:I Mathematical foundation and hypoplasticity[J].Journal of Engineering Mechanics,ASCE,1986,112(9):966-987.
[6]Hashiguchi K.Sub-loading surface model in unconventional plasticity[J].International Journal of Solids and Structures,1989,25(8):917-945.
[7]Hashiguchi K,Chen Z P.Elasto-plastic constitutive equation of soils with the sub-loading surface and the rotational hardening[J].International Journal for Numerical and Analytical Methods in Geo-mechanics,1998,22(3):197-227.
[8]Nakai T,Hinokio M.A simple elasto-plastic model for normally and over-consolidated soil with unified material parameters[J].Soils and Foundations,2004,44(2):53-70.
[9]孔亮,郑颖人,姚仰平.基于广义塑性力学的土体次加载面循环塑性模型(I):理论与模型[J].岩土力学,2003,24(2):141-145.(Kong L,Zheng Y R,Yao Y P.Sub-loading surface cyclic plastic model for soil based on generalized plasticity(Ⅰ):theory and model[J].Rock and Soil Mechanics,2003,24(2):141-145.(in Chinese))
[10]Sun D,Chen L W,Zhang J R.Bifurcation analysis of over-consolidated clays in different stress paths and drainage conditions[J].GeomechanicsAnd Engineering,2015,9(5),669-685.
[11]甄文战,孙德安,段博.超固结土本构模型分叉三维理论分析及数值模拟[J].岩土工程学报,2010,32(12):1910-1915.(Zhen W Z,Sun D A,Duan B.Theoretical analysis and numerical simulation of three-dimensionalbifurcation by constitutive model for over-consolidated clays[J].Chinese Journal of Geotechnical Engineering,2010,32(12):1910-1915.(in Chinese))
[12]Ng I T,Yuen K V,Lao N K.Probabilistic characterization of cyclic shear modulus reduction for normally to moderately over-consolidated clays[J].Earthquake Engineering and Engineering Vibration,2016,15(3),495-508.
[13]Sanchez F E,Aguado M B.Analysis of a dilatometer test in over-consolidated sediments,basin of the duero river,spain[J].Acta Geotechnica Slovenica,2015,12(1),36-47.
[14]张锋,叶冠林.计算土力学[M].北京:人民交通出版社,2007.(Zhang F,Ye G L.Computational Mechanics For Soil[M].Beijing:The People’s Communication Publishing Company,2007.(in Chinese))
[15]许东俊,耿乃光.岩石强度随中间主应力的变化规律[J].固体力学学报.1985,6(1):72-80.(Xu D J,Geng N G.The variation law of rock strength with increase of intermediate principal stress[J].Chinese Journal of Solid Mechanics,1985,6(1):72-80.(in Chinese))
[16]殷宗泽,赵航.中主应力对土体本构关系的影响[J].河海大学学报,1990,18(5):54-61.(Yin Z Z,Zhao H.Effect of middle principal stress on constitutive relationship[J].Journal of Hohai University(Natural Sciences),1990,18(5):54-61.(in Chinese))
[17]胡小荣,俞茂宏.材料三剪屈服准则研究[J].工程力学,2006,23(4):6-11.(Hu X R,Yu M H.Research on triple-shear yield criterion for materials[J].Engineering Mechanics.,2006,23(4):6-11.(in Chinese))
[18]胡小荣,俞茂宏.岩土类介质强度准则新探[J].岩石力学与工程学报,2004,23(18):3037-3043.(Hu X R,Yu M H.New research on failure criterion for geomaterial[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(18):3037-3043.(in Chinese))
[19]孙德安,陈波.重塑超固结上海软土力学特性及弹塑性模拟[J].岩土力学,2010,31(6):1739-1743.(Sun D A,Chen B.Mechanical behavior of remolded overconsolidated Shanghai soft clay and its elasto-plastic simulation[J].Rock and Soil Mechanics,2010,31(6):1739-1743.(in Chinese))
[2]Mita K A,Dasari G R,Lo K W.Performance of a three-dimensional Hvorslev-modified cam clay model for over-consolidated clay[J].International Journal of Geo-mechanics,ASCE,2004,4(4):296-309.
[3]Yao Y P,Hou W,Zhou A N.UH model:three-dimensional unified hardening model for over-consolidated clays[J].Geo-technique,2009,59(5):451-469.
[4]罗汀,侯伟,姚仰平.考虑渐近状态特性的超固结土本构模型[J].岩土力学,2010,31(3):683-688,694.(Luo T,Hou W,Yao Y P.An asymptotic state constitutive model for over-consolidated clays[J].Rock and Soil Mechanics,2010,31(3):683-688,694.(in Chinese))
[5]Dafalias Y F.Bounding surface plasticity:I Mathematical foundation and hypoplasticity[J].Journal of Engineering Mechanics,ASCE,1986,112(9):966-987.
[6]Hashiguchi K.Sub-loading surface model in unconventional plasticity[J].International Journal of Solids and Structures,1989,25(8):917-945.
[7]Hashiguchi K,Chen Z P.Elasto-plastic constitutive equation of soils with the sub-loading surface and the rotational hardening[J].International Journal for Numerical and Analytical Methods in Geo-mechanics,1998,22(3):197-227.
[8]Nakai T,Hinokio M.A simple elasto-plastic model for normally and over-consolidated soil with unified material parameters[J].Soils and Foundations,2004,44(2):53-70.
[9]孔亮,郑颖人,姚仰平.基于广义塑性力学的土体次加载面循环塑性模型(I):理论与模型[J].岩土力学,2003,24(2):141-145.(Kong L,Zheng Y R,Yao Y P.Sub-loading surface cyclic plastic model for soil based on generalized plasticity(Ⅰ):theory and model[J].Rock and Soil Mechanics,2003,24(2):141-145.(in Chinese))
[10]Sun D,Chen L W,Zhang J R.Bifurcation analysis of over-consolidated clays in different stress paths and drainage conditions[J].GeomechanicsAnd Engineering,2015,9(5),669-685.
[11]甄文战,孙德安,段博.超固结土本构模型分叉三维理论分析及数值模拟[J].岩土工程学报,2010,32(12):1910-1915.(Zhen W Z,Sun D A,Duan B.Theoretical analysis and numerical simulation of three-dimensionalbifurcation by constitutive model for over-consolidated clays[J].Chinese Journal of Geotechnical Engineering,2010,32(12):1910-1915.(in Chinese))
[12]Ng I T,Yuen K V,Lao N K.Probabilistic characterization of cyclic shear modulus reduction for normally to moderately over-consolidated clays[J].Earthquake Engineering and Engineering Vibration,2016,15(3),495-508.
[13]Sanchez F E,Aguado M B.Analysis of a dilatometer test in over-consolidated sediments,basin of the duero river,spain[J].Acta Geotechnica Slovenica,2015,12(1),36-47.
[14]张锋,叶冠林.计算土力学[M].北京:人民交通出版社,2007.(Zhang F,Ye G L.Computational Mechanics For Soil[M].Beijing:The People’s Communication Publishing Company,2007.(in Chinese))
[15]许东俊,耿乃光.岩石强度随中间主应力的变化规律[J].固体力学学报.1985,6(1):72-80.(Xu D J,Geng N G.The variation law of rock strength with increase of intermediate principal stress[J].Chinese Journal of Solid Mechanics,1985,6(1):72-80.(in Chinese))
[16]殷宗泽,赵航.中主应力对土体本构关系的影响[J].河海大学学报,1990,18(5):54-61.(Yin Z Z,Zhao H.Effect of middle principal stress on constitutive relationship[J].Journal of Hohai University(Natural Sciences),1990,18(5):54-61.(in Chinese))
[17]胡小荣,俞茂宏.材料三剪屈服准则研究[J].工程力学,2006,23(4):6-11.(Hu X R,Yu M H.Research on triple-shear yield criterion for materials[J].Engineering Mechanics.,2006,23(4):6-11.(in Chinese))
[18]胡小荣,俞茂宏.岩土类介质强度准则新探[J].岩石力学与工程学报,2004,23(18):3037-3043.(Hu X R,Yu M H.New research on failure criterion for geomaterial[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(18):3037-3043.(in Chinese))
[19]孙德安,陈波.重塑超固结上海软土力学特性及弹塑性模拟[J].岩土力学,2010,31(6):1739-1743.(Sun D A,Chen B.Mechanical behavior of remolded overconsolidated Shanghai soft clay and its elasto-plastic simulation[J].Rock and Soil Mechanics,2010,31(6):1739-1743.(in Chinese))