基于ANSYS建立的油松单根复合体模型的验证

目的]为了揭示林木根系固土的力学机制,以根土复合体为研究对象,应用有限元程序ANSYS 12.0,研究油松单根与土壤间的摩擦特性。方法]将根土复合体视为根、土和根土接触面3部分组成的离散化模型,油松单根采用线弹性本构模型,土体采用理想弹塑性本构模型。根据三轴压缩试验及根系拉拔试验计算出的模型参数,运用非线性有限元法模拟在不同埋深,不同直径下的单根拉拔试验。分析根土复合体的摩擦力与滑移量的变化关系,绘制关系曲线。将数值分析结果与拉拔试验数据进行对比。结果]有限元模拟结果与根系拉拔试验结果基本一致:根土间初始摩擦力和峰值摩擦力随根系的埋深和直径的增加而增大,峰值滑移量随根系埋深增加而增大。结论]建立的单根复合体有限元模型可以用于根土摩擦特性的研究,并为进一步对多角度的立体群根根系进行数值分析提供依据。

Verification of Pinus Tabulaeformis Root-Soil Model Based on ANSYS

Objective] In order to reveal the mechanism of soil reinforcement by roots, soil-root composites was selected to study the tribological properties between roots of Pinus tabulaeformis and soil by using the finite element program ANSYS 12.0.Methods] Soil-root composites was regarded as the discrete model which was composed of root, soil and root-soil contact face. The root was analyzed by the linear elastic constitutive model, and the soil was analyzed by the elastic perfectly plastic constitutive model. The model parameters were calculated according to the triaxial compression test. The pulling out test of single root was simulated by nonlinear finite element in different burial depths and various root diameters. The relationship between friction and slip is analyzed and the curve was drawn. The results from numerical analysis were used to compare with the experimental data from the pulling out test.Results] The results of the finite element numerical simulation were agree with the pulling out tests as the initial friction and peak friction increased with the increase of burial depth and root diameter.Conclusion] The established finite element model can be used for the analysis of the root-soil friction characteristics, and it provides the basis for further numerical analysis.