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从非饱和土的有效应力出发,对SFG模型进行了修正,将饱和度的影响引入到了模型当中,使得模型在不增加参数的同时可以反映更多的实验现象。首先简单介绍了SFG模型。然后以功的表达式推导得到的非饱和土有效应力为基础给出了非饱和土的体变方程,在饱和阶段该方程可以自动退化为饱和土的体变方程。结合土水特征曲线方程,推导得到了修正模型的加载湿陷屈服面方程,由此得到的屈服面方程不仅是吸力的函数,同时也是饱和度的函数。屈服面可以连续光滑地从饱和状态过渡到非饱和状态,并可以预测干燥时出现塑性变形的现象。此外它还可以反映SFG模型无法反映的现象,即考虑饱和度的影响,对于吸力相同饱和度不同的土样,给出的屈服应力将不同。最后利用已有试验数据对修正模型进行了验证,说明了修正模型与试验结果是相符的。
Based on the effective stress of unsaturated soils, the SFG model is modified and the influence of saturation is introduced into the model so that the model can reflect more experimental phenomena without increasing the parameters. First, a brief introduction to the SFG model. Then based on the effective stress of unsaturated soil derived from the expression of work, the body variable equation of unsaturated soil is given. The equation can be automatically degenerated into the body variable equation of saturated soil in the saturation phase. Combined with the equation of soil-water characteristic curve, the equation of load-bearing surface yielding for the modified model is deduced. The yield surface equation obtained is not only a function of suction but also a function of saturation. The yield surface can continuously and smoothly transition from the saturated state to the non-saturated state and predict the plastic deformation during drying. In addition, it can also reflect the phenomenon that the SFG model can not reflect, that is, considering the effect of saturation, yield stress will be different for soil samples with the same suction intensity. At last, the modified model is validated by the existing experimental data, which shows that the modified model is in good agreement with the experimental results.