修正广义Kelvin蠕变固结模型研究  

STUDY ON MODIFIED GENERALIZED KELVIN CREEP CONSOLIDATION MODEL

作　　者：陈晓平[1] 朱鸿鹄[2] 周秋娟[1] 

机构地区：[1]暨南大学力学与土木工程系,广东广州510632 [2]香港理工大学土木及结构工程学系

出　　处：《岩石力学与工程学报》2006年第z2期3428-3434,共7页Chinese Journal of Rock Mechanics and Engineering

基　　金：广东省自然科学基金资助项目(021145);广东省科技计划资助项目(2004B32801003);广东省水利厅科技计划资助项目(2003-13)

摘　　要：软土变形的时效特性产生于蠕变和固结,但蠕变和固结基于不同的变形机制,因此研究蠕变固结耦合效应的计算模型对于软土工程来说是十分重要的。采用将非线性本构模型和Biot固结模型耦合的方法,建立修正的广义Kelvin蠕变固结模型,即非线性弹-黏弹固结模型。首先,根据软土室内试验成果分析变形机制和应变随应力和时间的变化规律,找到函数拟合关系;其次,将Duncan模型和修正的广义Kelvin模型相结合,建立描述上述函数拟合关系的本构模型。然后,将该本构模型代入Biot固结理论的平衡方程,并提出基于非线性变形特征的蠕变固结模型。该模型共有14个模型参数,包括8个Duncan参数,均可通过常规三轴试验确定。通过一个实际工程的计算,完成该模型的计算流程,并对计算结果进行分析和比较,验证所建模型的有效性,探讨软土蠕变对地基中孔隙水压力及应力水平的影响,在此基础上获得一些有益的结论。研究结果表明,采用修正的广义Kelvin蠕变固结模型进行软土变形特性分析是一种合理的方法,具有模型机制明确、参数确定方法简单的优点。另外,虽然蠕变和固结都会给工程带来工后沉降问题,但两者对工程的影响是不一样的,改善地基的排水条件可弱化蠕变效应并提高工程的安全度。Time effect of soft soil deformation is caused by creep and consolidation that have different mechanisms.For soft foundation,it is important to study the calculation model considering creep-consolidation interaction.Because of the difficulty for the selection of model and its parameters,the coupling methods of nonlinear constitutive model and Biot consolidation model are adopted,and a nonlinear elastoviscous elastic consolidation model called modified generalized Kelvin creep-consolidation model is proposed.Based on laboratory tests of soft soilt,he relationships between strain,stress and time were studied and generalized Kelvin model is found to be the best to describe the approximately exponential creep phenomenon.Secondly,by means of combining Duncan model and modified generalized Kelvin model,a new constitutive model to describe stress-strain-time relationship is proposed.Thirdly,by considering the constitutive model with the Bito′s balance equation,the creep consolidation model based on nonlinear deformation characteristic is derived.This model has 14 parameters,including Duncan model′s 8 parameters,which can be determined by general triaxial tests.Through a case study,the model and calculation process are verified,and the influences of creep on the pore water pressure and stress lever are analyzed.Some useful conclusions are proposed.Research shows that modified generalized Kelvin consolidation model can perfectly describe the deformation mechanism of soft soil.In addition,the creep and consolidation can also cause post-construction settlement in engineering,but the effects are different.The improved drainage condition can weaken creep effect and guarantee the safety of projects.

关 键 词：土力学 软土地基 蠕变固结 KELVIN模型 

分 类 号：TU413.93[建筑科学—岩土工程] TU471.8[建筑科学—土工工程]