基于SFG模型的统一屈服面本构模型与试验研究

Constitutive model and experimental study of uniform yield surface based on SFG model

将SFG模型中的加载湿陷屈服面(LC屈服面)与BBM模型中提出的吸力增加屈服面(SI屈服面)统一成为单独光滑的屈服面,基于弹塑性理论框架,推导出相应的弹塑性本构模型。通过非饱和固结直剪试验对江西红土的模型计算参数的应力-应变曲线与试验结果进行对比。结果表明:模型对多种应力路径下非饱和三轴试验的计算结果与相应试验的测定结果较为吻合,验证了模型能较好地模拟非饱和土在多种应力路径下的体应变行为。统一屈服面简化了加载湿陷屈服面与吸力增加屈服面之间的耦合分析,解决了因双屈服面的不连续而造成计算不便问题,拓宽了SFG模型的适用性。

In this paper,the loading wet yield surface(LC yield surface)in the SFG model and the suction increasing yield surface(SI yield surface)proposed in the BBM model are unified into a single smooth yield surface.The corresponding elasto-plastic constitutive model is derived under the framework of elasto-plastic theory.The model calculation parameters of Jiangxi red clay were determined by unsaturated consolidation direct shear test.The calculation parameters are entered into the model program and the stress path of the unsaturated triaxial test is calculated by the program and compared against experimental results in a published paper.Based on stress-strain curves calculated from the comparison model and test results,we draw a conclusion that the calculation results of the unsaturated triaxial test model under different stress paths are in good agreement with the experimental results.It is verified that the model can better simulate the volumetric strain behavior of unsaturated soil under various stress paths than other models.Uniform yield surface simplifies the coupling analysis between loading wet yield surface and suction increasing yield surface.Our model solves the problem of inconvenience caused by the discontinuity of the double yield surface,and broadens the applicability of the SFG model.