基于均匀化理论的根土复合体三维本构关系  

Three-dimensional constitutive relation of the root-soil composite using homogenization theory

作　　者：戴靖沛 黄建坤 陈丽华[1,2,3] 及金楠[1,2,3] 李珺 Dai Jingpei;Huang Jiankun;Chen Lihua;Ji Jinnan;Li Jun(Forest Ecosystem Studies,National Observation and Research Station,Beijing Forestry University,Jixian 042200,China;Key Laboratory of State Forestry Administration on Soil and Water Conservation,School of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,China;School of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,China)

机构地区：[1]山西吉县森林生态系统国家野外科学观测研究站,北京林业大学,吉县042200 [2]北京林业大学水土保持学院水土保持国家林业局重点实验室,北京100083 [3]北京林业大学水土保持学院,北京100083

出　　处：《农业工程学报》2022年第13期76-83,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金“根土复合体的宏细观力学体系及力学性能研究”(32071841);国家自然科学基金“基于多尺度耦合模型的林木根系固土机制研究”(31700637);北京市教委生态修复工程学高精尖学科建设项目。

摘　　要：黄土高原水土流失严重,自然灾害频发,而植被可有效减少浅层滑坡,其中根系加固是对环境有利的土壤稳定措施。为定量研究植物根系对土体的增强效果以及根土复合体在力的作用下的变形发展规律,该研究将根土复合体视为天然纤维增强复合材料,基于均匀化理论,构建根土复合体的数值计算模型。利用有限元软件的二次开发功能,建立周期性边界条件,对根土复合体单胞的等效弹性模量和强度参数进行计算;通过根土复合体的三轴压缩试验和数值模拟,验证单胞计算理论的准确性;最后对单胞进行细观力学分析。研究表明:1)该研究建立的根土复合体单胞模型,可有效预测其等效弹性参数,与试验相比,轴向弹性模量相对误差为2.2%。2)单胞模型可以预测根土复合体的粘聚力c和内摩擦角φ,与试验相比,c和φ仅相差4.41k Pa和0.93°;在保证精度的同时大大提高了计算效率(与标准尺寸试件模型相比减少了90%的单元数)。3)根系的存在允许土体产生更大的变形和承受更大的应力。研究成果从周期复合材料的角度为黄土高原根系固土机理研究提供了新思路。Soil erosion and land degradation frequently occur on Loess Plateau in western China. Since the vegetation can effectively reduce shallow landslides, root reinforcement can be an environmentally beneficial soil stabilization measure in recent years. The Loess Plateau also presents a large number of plantation forests with a uniform arrangement. Among them, a periodic distribution can be found in the root system and biological characteristics. The traditional model of root reinforcement cannot consider the effect of roots on the elastic modulus of the root-soil composite. Meanwhile, it is difficult to calculate the shear strength of soil containing a large number of roots for the deformation of the root-soil composite. There is a strong coupling relationship between the plant roots and soil. In this study, a three-dimensional constitutive relation was constructed for the root-soil composite using the homogenization theory, in order to quantitatively the strengthening effect of plant roots on the soil and deformation development under the loads. The root-soil composite was regarded as the natural fiber-reinforced composite material. The equivalent elastic modulus and strength parameters of the root-soil composite Unit Cell(UC) were calculated via the periodic boundary conditions using the finite element software ABAQUS scripting interface. The UC model was added with the six types of load conditions, and then the equivalent stiffness matrix was solved to obtain the equivalent elastic parameters. A triaxial test and numerical simulation were also carried out to verify the strength parameters and calculation accuracy of the root-soil composite UC. Specifically, the UC model was loaded with vertical axial compression and horizontal confining pressure(100, 200, 300, and 400 kPa). A Duncan-Zhang E-B model was selected for the soil, following the Mohr-Coulomb yield criterion. Finally, the micro-mechanical analysis was also performed on the UC. The results show that: 1) The UC model of the root-soil composite effectively

关 键 词：土壤 数值方法 有限元法 均匀化理论 根系固土 三轴压缩试验 

分 类 号：TU457[建筑科学—岩土工程]