与应力相关的软土蠕变本构模型的建立和应用
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摘要
天津滨海地区软土层深厚且沉积时间短,故蠕变特性显著,修建于其上的各类型建筑物沉降历时时间长,准确预测地基的最终沉降量成为工程设计的难题.针对天津滨海软土开展了一系列三轴固结蠕变试验,得到了不同围压与应力水平下的应变-时间曲线.提出了与围压和应力水平相关联的Merchant模型参数的确定方法,揭示了模型中3个参数在相同围压下随着应力水平的增大而近似呈线性减小的规律.以此为基础,建立了反映时间效应的天津滨海软土三维非线性黏弹性蠕变本构模型,开发了有限元子程序.与实际工程的观测资料对比表明,该蠕变模型能有效模拟不同施工阶段路堤沉降量的非线性发展过程与沉降速率的变化规律.
The coastal area of Tianjin is covered with a deep layer of soft soil.The soft soil has experienced a short time of deposition and shows significant creep properties.Besides,the settling time of buildings constructed on the soft soil was long,so it is important to accurately predict the final settlement of soft ground.A series of triaxial consolidating creep tests were carried out,and strain-time curves under different confining stresses and stress levels were acquired.A method of determining Merchant model parameters related to confining stress and stress level was established.Three parameters of Merchant model were all reduced linearly with the stress level under the same confining stress.On this basis,a three-dimensional non-linear viscoelasticity constitutive model which reflects time effect was built.Subroutine of finite element was also developed.Compared with prototype observation data,the creep model can effectively estimate the nonlinear development of settlement and the change rule of settling rate of embankment in different construction stages.
The coastal area of Tianjin is covered with a deep layer of soft soil.The soft soil has experienced a short time of deposition and shows significant creep properties.Besides,the settling time of buildings constructed on the soft soil was long,so it is important to accurately predict the final settlement of soft ground.A series of triaxial consolidating creep tests were carried out,and strain-time curves under different confining stresses and stress levels were acquired.A method of determining Merchant model parameters related to confining stress and stress level was established.Three parameters of Merchant model were all reduced linearly with the stress level under the same confining stress.On this basis,a three-dimensional non-linear viscoelasticity constitutive model which reflects time effect was built.Subroutine of finite element was also developed.Compared with prototype observation data,the creep model can effectively estimate the nonlinear development of settlement and the change rule of settling rate of embankment in different construction stages.
引文
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[3]陈宗基.固结及次时间效应的单向问题[J].土木工程学报,1958(1):3-12.Chen Zongji.One dimensional problem of consolidation and secondary time effects[J].China Civil Engineering Journal,1958(1):3-12(in Chinese).
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[6]卢萍珍,曾静,盛谦.软黏土蠕变试验及其经验模型研究[J].岩土力学,2008,29(4):1041-1044.Lu Pingzhen,Zeng Jing,Sheng Qian.Creep tests on soft clay and its empirical models[J].Rock and Soil Mechanics,2008,29(4):1041-1044(in Chinese).
[7]闫澍旺,刘克瑾,李伟,等.天津滨海新区软黏土的蠕变特性及无屈服面模型研究[J].岩土力学,2010,31(5):1431-1436.Yan Shuwang,Liu Kejin,Li Wei,et al.Study of creep properties of soft clay in Tianjin Binhai new area and noyield-surface constitutive model[J].Rock and Soil Mechanics,2010,31(5):1431-1436(in Chinese).
[8]王元战,黄东旭,肖忠.天津滨海地区两种典型软黏土蠕变特性试验研究[J].岩土工程学报,2012,34(2):379-384.Wang Yuanzhan,Huang Dongxu,Xiao Zhong.Experimental research on creep properties of two typical soft clays in coastal region of Tianjin[J].Chinese Journal of Geotechnical Engineering,2012,34(2):379-384(in Chinese).
[9]Sivasithamparam N,Karstunen M,Bonnier P.Modelling creep behaviour of anisotropic soft soils[J].Computers&Geotechnics,2015,69:46-57.
[10]Duncan J M.Limitations of conventional analysis of consolidation settlement[J].Journal of Geotechnical Engineering,1995,121(9):517-518.
[11]费康,张建伟.ABAQUS在岩土工程中的应用[M].北京:中国水利水电出版社,2010.Fei Kang,Zhang Jianwei.Application of ABAQUS in Geotechnical Engineering[M].Beijing:China Water&Power Press,2010(in Chinese).
[12]刘斌.海相软土地基沉降模式的研究分析[D].天津:河北工业大学,2015.Liu Bin.Research and Analysis of Marine Sedimentation Patterns Soft[D].Tianjin:Hebei University of Technology,2015(in Chinese).
[2]Gibson R E.A one-dimensional consolidation problem with a moving boundary[J].Quart Appl Math,1960,18(2):123-129.
[3]陈宗基.固结及次时间效应的单向问题[J].土木工程学报,1958(1):3-12.Chen Zongji.One dimensional problem of consolidation and secondary time effects[J].China Civil Engineering Journal,1958(1):3-12(in Chinese).
[4]Barden L.Consolidation of clay with non-linear viscosity[J].Géotechnique,1965,15(4):345-362.
[5]陈晓平,白世伟.软土蠕变-固结特性及计算模型研究[J].岩石力学与工程学报,2003,22(5):728-734.Chen Xiaoping,Bai Shiwei.Research on creepconsolidation characteristic and calculating model of soft soil[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(5):728-734(in Chinese).
[6]卢萍珍,曾静,盛谦.软黏土蠕变试验及其经验模型研究[J].岩土力学,2008,29(4):1041-1044.Lu Pingzhen,Zeng Jing,Sheng Qian.Creep tests on soft clay and its empirical models[J].Rock and Soil Mechanics,2008,29(4):1041-1044(in Chinese).
[7]闫澍旺,刘克瑾,李伟,等.天津滨海新区软黏土的蠕变特性及无屈服面模型研究[J].岩土力学,2010,31(5):1431-1436.Yan Shuwang,Liu Kejin,Li Wei,et al.Study of creep properties of soft clay in Tianjin Binhai new area and noyield-surface constitutive model[J].Rock and Soil Mechanics,2010,31(5):1431-1436(in Chinese).
[8]王元战,黄东旭,肖忠.天津滨海地区两种典型软黏土蠕变特性试验研究[J].岩土工程学报,2012,34(2):379-384.Wang Yuanzhan,Huang Dongxu,Xiao Zhong.Experimental research on creep properties of two typical soft clays in coastal region of Tianjin[J].Chinese Journal of Geotechnical Engineering,2012,34(2):379-384(in Chinese).
[9]Sivasithamparam N,Karstunen M,Bonnier P.Modelling creep behaviour of anisotropic soft soils[J].Computers&Geotechnics,2015,69:46-57.
[10]Duncan J M.Limitations of conventional analysis of consolidation settlement[J].Journal of Geotechnical Engineering,1995,121(9):517-518.
[11]费康,张建伟.ABAQUS在岩土工程中的应用[M].北京:中国水利水电出版社,2010.Fei Kang,Zhang Jianwei.Application of ABAQUS in Geotechnical Engineering[M].Beijing:China Water&Power Press,2010(in Chinese).
[12]刘斌.海相软土地基沉降模式的研究分析[D].天津:河北工业大学,2015.Liu Bin.Research and Analysis of Marine Sedimentation Patterns Soft[D].Tianjin:Hebei University of Technology,2015(in Chinese).