从各向异性的角度解释和模拟土的非共轴特性  

Explanation and modeling of non-coaxiality of soils from anisotropy

作　　者：田雨 姚仰平[1] 罗汀[1] TIAN Yu;YAO Yang-ping;LUO Ting(School of Transportation Science and Engineering, Beihang University, Beijing 100191, China)

机构地区：[1]北京航空航天大学交通科学与工程学院,北京100191

出　　处：《岩土力学》2018年第6期2035-2042,共8页Rock and Soil Mechanics

基　　金：国家重点基础研究发展计划项目(973计划)(No.2014CB047001);国家自然科学基金项目(No.11672015;No.51579005)~~

摘　　要：从发挥面的角度出发,分析论证各向异性是引起岩土材料出现非共轴现象的根本原因,得到与材料力学一致的结论。当共轭的两发挥面与沉积面的夹角不相等时,主应力面上将出现塑性应变增量的切向分量,所以塑性应变增量的主方向与应力的主方向非共轴。按照这一结论,对非共轴的数值模拟,也应当根据各向异性本构模型进行。为考虑各向异性影响新近提出的各向异性变换应力法,改变了各应力分量的相对大小,得到的各向异性变换应力张量与真实应力张量的主方向不一致,因此也能反映非共轴。利用各向异性变换应力法,能够在现有的弹塑性本构模型的框架下,描述土的非共轴现象。以各向异性UH模型为例,预测各种加载条件下的非共轴变形,验证了该方法的有效性。From the point of view of the mobilized plane, material anisotropy has been proved to be the fundamental reason to cause the non-coaxiality of soils, which is consistent with a conclusion in the material mechanics. When angles between the two conjugate mobilized planes and the bedding plane are not equal, shear components of the plastic strain increment will occur in the principal stress plane. As a result, the direction of principal plastic strain increment will not be coaxial with the direction of principal stress. Based on this conclusion, numerical modeling of non-coaxiality should also be carried out according to an anisotropic constitutive model. The newly proposed anisotropic transformed stress method considering the effect of anisotropy is also capable of reflecting the non-coaxiality, because it changes the relative magnitudes of stress components and obtains an anisotropic transformed stress tensor with different principal directions from the ordinary stress tensor. Using this method, non-coaxial behaviors of soils can be described under the framework of the existing elastoplastic constitutive models. As an example, the anisotropic UH model is adopted to predict the non-coaxial deformation under different loading conditions to verify this method.

关 键 词：土 非共轴 各向异性 变换应力 本构模型 

分 类 号：TU43[建筑科学—岩土工程]