层状土持水性室内模拟初步研究

Preliminary Study on Water Retention of Layered Soil by Laboratory Simulation

为了探究不同水势下层状土体和均质土体的持水性能,通过设置5个均质土体和4个层状土体(粗夹细、上粗下细、上细下粗和细夹粗),利用高速离心机法比较分析了不同均质和层状土体在不同水吸力下的持水性。结果表明:层状土体的持水能力要高于相同土壤材料配比下均匀混合的均质土,其中粗夹细层状土体的含水量平均增加了0.025 cm 3/cm 3;细质地土壤的数量较土体结构对持水性的影响更大;常见的水分特征曲线模型被用来模拟均质和层状土体,基于各模型的决定系数(R 2)和均方根误差(RMSE),可知van Genuchten模型拟合效果最好;van Genuchten模型拟合参数结果表明,层状土体的滞留含水量和饱和含水量大于相同土壤材料配比下的均质土,而拟合的形状参数α值较均质土则减小。试验表明:相同材料配比下,层状土的保水能力要高于均质土,且粗夹细层状土有更强的持水能力。另外,质地较细土壤含量对土壤持水性的影响要大于土体结构。

To reveal the water holding performance of the layer and homogeneous soil at different water potentials,five homogeneous soils and four layered soils(fine embedded into coarse,coarse covered with fine,fine covered with coarse and coarse embedded into fine)were set up to study their soil water retention curves by high-speed centrifuge method.The results show that the water retention capacity of the layered soil is higher than that of the homogeneous soil under the same soil material ratio;the water retention capacity in the treatment of coarse sandwiched fine is the highest,and the water content increases by 0.025 cm 3/cm 3 on average;under the same external suction,the effect of the amount of fine soil on soil water holding capacity is greater than that of soil structure;the soil water retention curve of layered soil can be simulated by the commonly models;the fitting accuracy of van Genuchten model is higher than the Brooks-Corey and Log normal distribution models based on the coefficient of determination(R 2)and root mean square error(RMSE);the simulated parameters of soil water retention curve by the van Genuchten model indicate that the saturated water content and residual water content of the homogeneous soil are lower than those of layered soil,and the shape parameterαof homogeneous soils is higher than that of layered soil under the same soil material ratio.The results show that the water holding capacity of layered soil is higher than that of homogeneous soil under the same material ratio,and the water holding capacity of fine embedded into coarse is stronger.In addition,the effect of soil content with fine texture on soil water retention is greater than that of soil structure.