大孔隙对土壤水分入渗特性影响的物理模拟试验

Physical simulation experiments of effects of macropores on soil water infiltration characteristics

利用不同粒径砂石和大孔隙域模具模拟同一深度、不同有效面孔隙度,在特制试验装置中研究积水条件下大孔隙流的三维运移行为。结果表明:湿润峰平齐且稳定的转折时间和有效面孔隙度相关性较高;不同有效面孔隙度条件下累积入渗量符合Kostiakov模型但其参数是有效面孔隙度的函数;大孔隙的连通性在一定条件下对土壤水分的优先入渗起主导作用;大孔隙的存在导致大孔隙中心特征剖面湿润面积发生典型变化,给出了大孔隙中心特征剖面湿润面积增量的定量概念及其与有效面孔隙度之间的数学模型,并进行了验证,精度满足要求。

The different size sands and macropores＇ mold were used to simulate the same macropores＇ depth and different effective surface macropores, and a novel soil column was designed to observe the 3D infiltration of macropore flow under the condition of ponding water. The results showed that there was high correlation between the time when the wetting front turned to flush and stable and the effective surface macropore. The cumulative infiltration was in line with the Kostiakov model while its parameters were associated with the effective surface macropores. Under certain conditions, macropores connectivity played the dominant role for the preferential infiltration in soil. The presence of macropores could lead to typical change of the center profile＇s wet area. In the end, the study gave a quantitative concept for the center profile＇s wet area increment and its mathematical model with the effective surface macropores. The accuracy of the model verified by experiments can meet the requirments.