考虑应力方向依赖性的砂土等效统一硬化模型研究  

Equivalent unified hardening model of sand considering the stress direction dependence

作　　者：董彤 孔亮[3] 王兴 房雨雨 刘超 DONG Tong;KONG Liang;WANG Xing;FANG Yuyu;LIU Chao(Institute of Defense Engineering,Academy of Military Sciences,People's Liberation Army,Beijing 100850,China;State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact,Army Engineering University of PLA,Nanjing,Jiangsu 210007,China;School of Sciences,Qingdao Technological University,Qingdao,Shandong 266033,China)

机构地区：[1]军事科学院国防工程研究院,北京100850 [2]陆军工程大学爆炸冲击防灾减灾国家重点实验室,江苏南京210007 [3]青岛理工大学理学院,山东青岛266033

出　　处：《岩石力学与工程学报》2022年第9期1935-1944,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51909268,12172187);博士后创新人才支持计划(BX2021115)。

摘　　要：土的应力方向依赖性是指土的力学特性随应力方向改变而改变的性质,其内在原因是颗粒堆积形成的土体在微观尺度上具有各向异性。为了定量描述各向异性颗粒材料沿不同方向孔隙特征的差异,提出孔隙面积比的概念,即颗粒材料某一截面上孔隙面积与颗粒面积之比,并建立孔隙面积比与组构张量之间的定量关联。在此基础上,将各向异性状态参数定义为当前方向的孔隙面积比与孔隙面积比的平均值(或孔隙比)的差值,以定量描述材料不同方向的状态与平均状态之间的关系。进而采用等效应力法对砂土UH模型进行“改造”,建立砂土的EUH模型。EUH模型仅增加了2个试验参数,便可以很好地反映应力路径、孔压、应力-应变关系的应力方向依赖性,实现了对主空间和物理空间中各应变分量应力方向依赖性的精确预测,进一步验证了等效应力法的科学性,为等效应力法的工程应用奠定了坚实基础。The stress direction dependence of soil refers to the property that the mechanical properties of soil change with the change of the stress direction. The inner reason for the special property is that the soil formed by particle accumulation is anisotropic on the micro scale. To quantitatively describe the difference of pore characteristics of anisotropic granular materials along different directions,the pore area ratio is proposed,that is,the ratio of the pore area to the particle area on a certain section of granular material. Then,the quantitative correlation between the pore area ratio and the fabric tensor is established. On this basis,the anisotropic state parameter is defined as the difference between the pore area ratio in the current direction and the average value of the pore area ratio(or the value of the pore ratio),so as to quantitatively describe the relationship between the state in different directions and the average state of the material. The equivalent stress method is used to “transform” the unified hardening model(UH model),and the equivalent unified hardening model(EUH model) is established. Only two new parameters are added in the new model which can be directly obtained by the triaxial compression tests. The stress direction dependence of the stress path,pore pressure,stress-strain relationship can be accurate predicted.Moreover,the accurate prediction of the stress direction dependence of each strain component in the main space and physical space is also realized. The result further verifies the scientificity of the equivalent stress method,and lays a solid foundation for the engineering application of the equivalent stress method.

关 键 词：土力学 应力方向依赖性 等效应力法 UH模型 孔隙面积比 状态参数 

分 类 号：TU431[建筑科学—岩土工程]