基于混合物法则根土复合体本构模型的研究

为探究根土复合体的应力-应变关系，将其视为两相体，根系采用线弹性模型，土体采用邓肯-张模型，并考虑根系与土体之间的相对滑移关系，基于混合物法则建立根土复合体本构模型。通过素土与不同含根量的根土复合体三轴压缩试验，得到其应力-应变关系，通过单根拉伸试验得到根系的弹性模量。结果发现，(1)根土复合体的极限主应力差随含根量的增加先增加后减小，含根量0.3%为最优含根量。(2)单根的直径与抗拉力、抗拉强度符合幂函数关系，与弹性模量符合多项式关系。(3)通过反分析的方法，建立滑移关系，得到模型计算值的应力-应变关系，发现模型计算值与试验值的拟合度(R²)为0.96。该研究为根土复合体本构模型的建立提供新思路，并为根土复合体的数值分析提供参数。

Study on constitutive model of root soil complex based on mixture rule

In order to explore the stress-strain relationship of a root soil complex,it is considered as a two-phase body.A linear elastic model is used for the root system,and the Duncan-Chang model is used for the soil.Considering the relative slip relationship between the root system and the soil,the constitutive model of the root soil complex is established based on the mixture rule.Through the triaxial compression test of plain soil and root soil complex with different root contents,the stress-strain relationship is obtained.The elastic modulus of the root is obtained through the single root tensile test.The results show that (1) the ultimate principal stress difference of the root soil composite increases first and then decreases with the increase of root content,and the optimal root content was 0.3%.(2) The diameter of a single root conforms to the power function relationship with the tensile strength,and to the polynomial relationship with the elastic modulus.(3) Through the inverse analysis method,the slip relationship is established.The stress-strain relationship of the calculated value of the model is obtained.It is found that the fitting accuracy (R²) of the calculated value of the model and the test value is 0.96.This study provides a new idea for the establishment of the constitutive model of root soil composite,and provides parameters for the numerical analysis of a root soil complex.