砂土应力路径不相关的修正塑性功硬化参量与函数  

MODIFIED PLASTIC-WORK HARDENING PARAMETER AND FUNCTION INDEPENDENT OF STRESS PATH FOR SANDY SOIL

作　　者：彭芳乐[1,2] 白晓宇[1] 亚辛 龙冈文夫[4] 

机构地区：[1]同济大学地下建筑与工程系,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092 [3]孟加拉理工大学土木工程系,孟加拉国达卡1000 [4]东京理科大学土木工程系,日本千叶278-8510

出　　处：《岩石力学与工程学报》2008年第6期1171-1180,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(50679056);教育部新世纪优秀人材支持计划基金项目(NCET–06–0378);上海市曙光计划项目(05SG25);教育部留学回国人员科研启动基金项目

摘　　要：砂土的变形强度特性明显存在着应力路径效应,因此在砂土的弹塑性本构建模时硬化参数和函数的选取并不是一个简单的事情。针对砂土的这一特性,用密实砂土进行一系列多应力路径的平面应变压缩试验。试验结果表明,所有的应变增量(例如轴向、横向、剪切以及体积应变等增量)及塑性功增量都与应力路径具有较大的相关性,因而在传统的砂土弹塑性分析中利用以上任何一个状态量作为硬化参数并假设其与应力路径不相关是不合理的。基于广泛的多应力路径平面应变压缩试验结果以及细致的数据处理分析,发现一个特殊的修正塑性功参量以及相关的函数,它们与应力路径不相关,因此在砂土的弹塑性解析中假定它们作为硬化参量和函数是与理论假设一致的。理论计算结果与室内试验相比较表明,利用提出的修正塑性功作为硬化参数和硬化函数所构成的砂土的弹塑性模型可以很好地模拟砂土材料变形及强度的应力路径效应。It is not simple to select the hardening parameter and function in the constitutive modeling of elastoplastic behavior for sandy soils due to the fact that there exists a clear effect of stress path on the deformation and strength of sandy soils. In order to better understand the above effect, a series of drained plane strain compression（PSC） tests along different stress paths are carried out on saturated dense specimens of sandy soil with precise stress and strain measurements. It is shown that all the strain increments（i.e, axial, lateral, shear and volumetric increments） are dependent on stress history and stress path. Therefore, the use of any quantity shown above as the hardening parameter that is independent of stress history and path in an elastoplastic model for sandy soil is not reasonable. Based on test results and precise data analysis, a unique modified plastic-work parameter and the related function, which are independent of stress path, are discovered. It is shown that using the modified plastic-work parameter and function as the hardening parameter and function that is independent of stress path in an elastoplastic model for sandy soil is consistent with theoretical assumption. By the comparison between the computational results and the experimental results, it can be seen that the effect of stress path on the deformation and strength of sandy soil could be successfully simulated by the elastoplastic model with the proposed modified plastic-work parameter and function.

关 键 词：土力学 砂土 平面应变压缩试验 应力路径 硬化参数和函数 弹塑性模型 

分 类 号：TU44[建筑科学—岩土工程]