多因素作用下浑水入渗对土壤导水特性的影响

浑水土壤入渗具有复杂的上边界变化过程,其上边界导水能力的变化规律是研究浑水土壤入渗特性的重要基础。为研究浑水入渗形成致密层过程中导水率的变化情况,该研究进行了17组(9组正交试验处理,8组用于模型验证)浑水饱和土柱入渗试验,通过对试验结果进行多元回归构建多因素(浑水含沙率、黏粒含量及入渗时间)影响下砂土导水率动态模型;并结合浑水饱和土柱入渗特性进行合理假设,分别建立浑水砂壤土和粉壤土饱和土柱导水率动态模型并进行验证。结果表明:浑水含沙率、黏粒含量及入渗时间对砂土导水率影响极显著(P<0.01),入渗时间为砂土影响导水率变化的主要因素,其次为含沙率和黏粒含量;建立的砂土导水率动态模型决定系数为0.853,均方根误差为0.004 cm/min,表明该模型可客观反映各因素与导水率之间的关系;模型验证试验结果中均方根误差小于0.01 cm/min,相对误差绝对值均值小于7%,说明该导水率动态模型可靠性较高;砂壤土和粉壤土导水率动态模型决定系数分别为0.912和0.930,均方根误差分别为2×10^-3和5×10^-5 cm/min;模型验证中均方根...

Effects of muddy water infiltration on the hydraulic conductivity of soils by multiple factors

The infiltration of muddy water in soil has a complex change of upper boundary process. Among them, the hydraulic conductivity of soil has been one of the most important indicators for the infiltration characteristics of muddy water in the soil. In this study, a series of infiltration tests (9 orthogonal test treatments and 8 groups for the model validation) were performed on the muddy water in the saturated soil column. The hydraulic conductivity of the formed dense layer was also determined during the infiltration of muddy water. The dynamic model was then constructed for the hydraulic conductivity of the sand under multiple factors (sand content of muddy water, clay content, and infiltration time) using multiple regression. A verification test was made on the dynamic models of the hydraulic conductivity of the saturated soil columns in the muddy sandy and silt loam soil. It was assumed that the muddy water was infiltrated into the saturated soil column. The results showed that there were highly significant effects of the muddy water sand content, clay content, the gradation of sediment particles, and infiltration time on the hydraulic conductivity of the sand (P <0.01). The first factor was the infiltration time, followed by the sand content, and the last was the clay content. The coefficient of determination (R²) was 0.85 in the dynamic model for the hydraulic conductivity of sand, and the root mean square error was 0.004 cm/min, indicating the better-represented relationship between various factors and hydraulic conductivity. Meanwhile, the RMSE was less than 0.01 cm/min, and the mean absolute value of relative error was less than 7%, indicating the highly reliable dynamic model of hydraulic conductivity. The R² values of the dynamic model were 0.912 and 0.930 for the sandy and silt loam, respectively, and the RMSEs were 2×10⁻³ and 5×10⁻⁵ cm/min, respectively. The RMSEs were less than 0.01 cm/min, and the mean absolute value of relative error was less than 17% in the model validation, indicating the excellent agreement between the calculated and measured. The finding can greatly contribute to the theoretical basis of the infiltration process of muddy water in the soil, together with the barrier mechanism of the dense layer.