应力路径对土剪胀性的影响规律及其本构模型

项目名称： 应力路径对土剪胀性的影响规律及其本构模型

项目编号： No.50879001

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 轻工业、手工业

项目作者： 罗汀

作者单位： 北京航空航天大学

项目金额： 35万元

中文摘要： 土的剪胀性以及描述剪胀规律的剪胀方程是建立弹塑性本构模型的核心，采取部分塑性体积应变与塑性剪切应变有耦合的思路，将统一硬化参量分解为非耦合硬化参量与耦合硬化参量建立的渐进状态模型是能连续反映渐近状态曲线上土应力应变关系的本构模型，该模型能较合理描述粘土和砂土在不同应力路径下的剪胀特性，反映土在不同应力路径下的应力应变特性。在饱和砂土的渐近状态模型的基础上建立了能够描述不同应力路径下土的超固结性和渐近状态特性的模型。考虑到K0固结土的广泛存在性，将正常固结土的渐近状态模型推广到K0固结土的渐近状态模型。在强度准则方面，建立了土的三维渐近状态准则，该强度表达式中简单应力条件下的试验是不排水三轴压缩试验、不排水三轴伸长试验。基于SMP准则，通过主应力空间和物理空间的变换，以沉积面和SMP的最小夹角α20026;参数提出了一个各向异性强度峰值，得到一个适用于横观各向同性岩土材料的各向异性强度准则。在有限元应用方面，通过把非对称刚度矩阵对称化的方法解决了由于弹塑性刚度矩阵非对称导致有限元分析不容易收敛的问题。将UH模型推广应用到复杂加载情况，进行了循环荷载作用下地基承载力有限元模拟。

中文关键词： 渐近状态；各向异性；K0固结；非对称刚度矩阵

英文摘要： The stress path has great influence on the dilatancy of soils and hence the deformation and strength behaviors of soils are strongly stress path dependent. An asymptotic state model is proposed to describe the influence of stress paths on the dilatancy and the stress-strain behaviors of soils reasonably. Next, a three-dimensional asymptotic state criterion is proposed based on the asymptotic state concept and the generalized nonlinear strength criterion. Furthermore, based on the SMP criterion, assuming that the friction angle is changed with the angle between deposition surface and the SMP, a new expression of anisotropic peak strength Mαs proposed, which is the function of the minimum angle between deposition surface and the SMP. In the study, the asymptotic state model for saturated sand is also developed to an asymptotic state model for overconsoilidated clays (including K0 consolidated condition) to describe the overconsoilidated and asymptotic state behaviors of clays based on the UH model. Finally, the proposed model is applied to the FEM and the numerical simulation of the bearing capacity of foundation are performed under complex loading. The symmetrization method of tangential stiffness matrix for the UH models is used to improve the convergence of finite element analysis and reduce analysis time obviously.

英文关键词： asymptotic state; anisotropic; K0 consolidation; symmetric stiffness matrix