摘要
基于改进伏斯列夫面超固结黏土三维本构模型,利用有限元软件ABAQUS材料子程序接口,采用回映应力更新算法,实现了该模型在有限元分析中的应用。通过该模型与比奥固结理论的耦合,对超固结比为8的超固结黏土在三轴压缩、三轴伸长及平面应变应力条件下的变形局部化问题,进行了水-土耦合弹塑性有限元分析。分析结果表明:剪切带带内、带外点经历不同应力路径;剪切带带外单元经历了体缩、剪胀及被吸水体缩过程,而剪切带带内单元一直保持剪胀趋势;剪切带的形成伴随着剪胀,剪切带内、外出现了负的孔压,且孔压的分布也具有局部化特性。关于剪切带带内、外的孔隙水压及体变变化趋势与剪切速率有关,而平面应变介于三轴压缩与三轴伸长之间,但平面应变较早出现剪切带。孔隙水的迁移速度影响剪切带带内单元的剪胀,进而影响剪切带的形成及发展;而围压和弱单元位置也对剪切带的形成也有影响。
An improved Hvorslev envelope-based three-dimensional elastoplastic model for overconsolidated clay was proposed by Yao et al （2009）. The return mapping algorithm is adopted in order to implement the model into a finite element analysis software ABAQUS through the user material subroutine （UMAT） interface. 13y coupling the model with Biot＇s consolidation theory, three dimensional coupled analyses of an overconsolidated clay specimen in triaxial compression and extension and plane strain stresses are performed. The numerical results show that, different stress paths are seen inside and outside the shear band. The elements in the vicinities of the shear band take on volume contraction, dilatancy and contraction due to being sucked, while the elements inside the shear band keep the dilatancy during shearing. Dilatancy is accompanied by the development of the shear band, so the negative pore pressure appears inside the shear band and their vicinities. The changes in the pore pressure and volumetric strain in plane strain are between triaxial compression and extension stresses and depend on the shear velocity, but the shear bands early occur in plane strain condition. The migration of the pore water controls the formation and development of the shear band. The confining pressure and location of the weak element also play an important effect on the formation of shear bands.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2011年第1期293-298,共6页
Rock and Soil Mechanics
基金
国家自然科学基金资助项目(No.10972130)
关键词
超固结土
孔压
剪胀
三维应力
剪切带
overconsolidated clay
pore pressure
dilatancy
three-dimensional stress
shear band
