超固结土的弹粘塑性本构关系

项目名称： 超固结土的弹粘塑性本构关系

项目编号： No.11272031

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 数理科学和化学

项目作者： 姚仰平

作者单位： 北京航空航天大学

项目金额： 86万元

中文摘要： 土的应力应变关系时间相关性被称作粘性。与土粘性相关的现象包括蠕变和加载率效应，它们会使土的工程性质发生改变，进而导致地基沉降以及边坡失稳等工程问题。因此，长期以来人们对粘土的应力应变关系时间相关性进行了大量的试验研究，并建立了许多本构模型来描述土的粘塑性本构关系。但是，目前的本构模型对土的蠕变压力依存性等粘性基本规律的描述还有所欠缺，同时也不能合理反映土在时间效应下产生超固结后所具有的剪胀、软化等性质。本项目拟在对饱和粘土的蠕变及加载率效应进行试验探索的基础上，研究蠕变和加载率影响下的饱和粘土应力应变特性，并通过蠕变的压力依存性来考虑蠕变和加载率效应的耦合，构造饱和粘土新的简单合理的一维应力-应变-时间-加载率关系框架，将其与申请者提出的超固结土本构模型结合以实现时间效应与超固结的耦合，建立三维弹粘塑性本构模型，最后将新本构模型嵌入到有限元程序以模拟实际的岩土工程问题。

中文关键词： 三维；粘塑性；蠕变；本构模型；超固结土

英文摘要： Time-dependent behaviour of clays is known as viscosity. The phenomema related to viscosity of clays include creep and rate dependency, which would change the engineering properties of clays and result in such engineering problems as ground settlements and landslides. Therefore, numerous studies on viscosity have been done and large numbers of constitutive models have been built to describe viscoplasticity of clays. However, the existing models can neither describe stress-dependency of creep nor reflect shear dilatancy and strain-softening of over-consolidated clays. So this project plans to research time-dependent stress-strain behaviour of clays, based on creep and rate tests on saturated clays as well as analyses on the lots of existing experimental data. Through considering the co-effect of creep and rate dependency, one-dimensional stain-stress-time-rate relationship will be formulated. Besides, the fomula of the relationship is to be combined with the over-consolidated clay model proposed by the applicants to build an elastic visco-plastic model which will be able to describe over-consolidated clays with time-dependency. Finally the proposed model is going to be incorperated into the finite element analysis softwares to simulate practical problems of geotechnical engineering.

英文关键词： Three-dimension；Viscoplasticity；Creep；Constitutive model；Overconsolidated clay