在土水特征测定试验的基础上,分析了历史上提出的各种模拟土水特征曲线的方程与试验结果的拟合程度。在非饱和渗透系数试验结果的基础上,分析了由分维理论得到的非饱和渗透系数模拟方程与试验结果的拟合程度。得出以下结论:Fredlund and...在土水特征测定试验的基础上,分析了历史上提出的各种模拟土水特征曲线的方程与试验结果的拟合程度。在非饱和渗透系数试验结果的基础上,分析了由分维理论得到的非饱和渗透系数模拟方程与试验结果的拟合程度。得出以下结论:Fredlund and Xing土水特征曲线方程对于试验结果有较好的模拟效果;Brooks和Corey土水特征曲线方程与试验结果的曲线形状更为接近,但在模拟接近309MPa的吸力段的土水曲线时与试验结果有偏差。分维理论的修正公式能更好模拟非饱和渗透系数。展开更多
An accurate mathematical representation of soil particle-size distribution(PSD) is required to estimate soil hydraulic properties or to compare texture measurements using different classification systems. However, man...An accurate mathematical representation of soil particle-size distribution(PSD) is required to estimate soil hydraulic properties or to compare texture measurements using different classification systems. However, many databases do not contain full PSD data,but instead contain only the clay, silt, and sand mass fractions. The objective of this study was to evaluate the abilities of four PSD models(the Skaggs model, the Fooladmand model, the modified Gray model GM(1,1), and the Fredlund model) to predict detailed PSD using limited soil textural data and to determine the effects of soil texture on the performance of the individual PSD model.The mean absolute error(MAE) and root mean square error(RMSE) were used to measure the goodness-of-fit of the models, and the Akaike's information criterion(AIC) was used to compare the quality of model fits. The performance of all PSD models except the GM(1,1) improved with increasing clay content in soils. This result showed that the GM(1,1) was less dependent on soil texture.The Fredlund model was the best for describing the PSDs of all soil textures except in the sand textural class. However, the GM(1,1) showed better performance as the sand content increased. These results indicated that the Fredlund model showed the best performance and the least values of all evaluation criteria, and can be used using limited soil textural data for detailed PSD.展开更多
文摘在土水特征测定试验的基础上,分析了历史上提出的各种模拟土水特征曲线的方程与试验结果的拟合程度。在非饱和渗透系数试验结果的基础上,分析了由分维理论得到的非饱和渗透系数模拟方程与试验结果的拟合程度。得出以下结论:Fredlund and Xing土水特征曲线方程对于试验结果有较好的模拟效果;Brooks和Corey土水特征曲线方程与试验结果的曲线形状更为接近,但在模拟接近309MPa的吸力段的土水曲线时与试验结果有偏差。分维理论的修正公式能更好模拟非饱和渗透系数。
基金supported by the Rice Research Institute, Rasht of Iran
文摘An accurate mathematical representation of soil particle-size distribution(PSD) is required to estimate soil hydraulic properties or to compare texture measurements using different classification systems. However, many databases do not contain full PSD data,but instead contain only the clay, silt, and sand mass fractions. The objective of this study was to evaluate the abilities of four PSD models(the Skaggs model, the Fooladmand model, the modified Gray model GM(1,1), and the Fredlund model) to predict detailed PSD using limited soil textural data and to determine the effects of soil texture on the performance of the individual PSD model.The mean absolute error(MAE) and root mean square error(RMSE) were used to measure the goodness-of-fit of the models, and the Akaike's information criterion(AIC) was used to compare the quality of model fits. The performance of all PSD models except the GM(1,1) improved with increasing clay content in soils. This result showed that the GM(1,1) was less dependent on soil texture.The Fredlund model was the best for describing the PSDs of all soil textures except in the sand textural class. However, the GM(1,1) showed better performance as the sand content increased. These results indicated that the Fredlund model showed the best performance and the least values of all evaluation criteria, and can be used using limited soil textural data for detailed PSD.
