砂土内在各向异性的本构模拟  

Constitutive modeling of fabric anisotropy of sand

作　　者：明海燕[1] 李相崧[2] Y.F.Dafalias 

机构地区：[1]深圳大学土木工程学院深圳市土木工程耐久性重点实验室,深圳518060 [2]香港科技大学土木工程系 [3]加州大学戴维斯分校土木工程系

出　　处：《深圳大学学报（理工版）》2007年第4期331-338,共8页Journal of Shenzhen University(Science and Engineering)

基　　金：中国国家自然科学基金资助项目(50678103);香港特别行政区研究资助局资助项目(HKUST6002/02E);美国国家自然科学基金资助项目(CMS-0201231);广东省自然科学基金资助项目(7009408);深圳市科技计划资助项目(200625)

摘　　要：基于砂土的应力-应变-强度关系受土骨架结构朝向和主应力方向间相对关系影响,相同状态砂土在三轴压缩条件下剪切膨胀,在三轴拉伸条件下剪切收缩的研究.介绍一个模拟砂土内在各向异性的本构模型.模型采用描述材料内在各向异性的二阶对称组构张量和各向异性状态变量(组构张量和应力张量的联合不变量)描述土的各向异性.在e-p平面,临界状态线不固定,而与各向异性状态变量相关.塑性模量也与各向异性状态变量相关.模型能在很大应力和密度变化范围内模拟砂土的剪缩和剪胀行为,特别是主应力方向和土骨架结构朝向间夹角对砂土性质的影响.模拟结果与实验数据吻合.Recent laboratory investigations indicate that the stress-strain-strength responses of loose sands are appreciably affected by the fabric orientation of the soil with respect to the frame of principal stresses. A sand specimen exhibiting a dilative response during triaxial compression may show a contractive response during triaxial extension under otherwise identical conditions. A plasticity constitutive model for simulating inherently anisotropic sand behavior is presented. A second-order symmetric fabric tensor is defined to describe the material inherent anisotropy. The location of the critical state line is not fixed but modified to be a function of the anisotropic state variable, which is a scalar defined in terms of a joint invariant of the fabric tensor and the stress tensor. The plastic modulus is also modified to be dependent on the anisotropic state variable. By these two modifications, an existing bounding surface model can successfully simulate both the contractive and dilative responses of sand over a wide range of variations in stress and density.

关 键 词：砂土 各向异性 本构模型 剪胀性 塑性 

分 类 号：TU45[建筑科学—岩土工程]