不同大孔隙深度对土壤水分入渗特性的影响

The Effect of the Infiltration Characteristics Under the Different Macropores' Depth in the soil

利用特定粒径砂石和特制模具模拟同一有效面孔隙度、不同深度的大孔隙域,研究积水入渗条件下水分在其中的三维运移行为。实验研究表明,大孔隙的存在导致水分入渗湿润锋在入渗初期剧烈紊动,但随着入渗的推移湿润锋逐渐平稳且其稳定的转折时间和孔隙深度相关性较高;大孔隙域的存在使得水分迅速充满孔隙域并到达大孔隙域底部,造成初期水分垂直和径向两部分入渗,累积入渗增量随着孔隙深度的增大而加大并与孔隙深度呈一定的函数关系;大孔隙域的存在使得湿润锋在转折时间Tp前后表现出不同的现象,大孔隙域中心处的湿润锋为入渗过程中的最深值即特征湿润锋Zmf,实验分析Zmf与孔隙深度Z在转折时间Tp前后呈同一函数关系但前后系数不同。利用偏差Ip对所建立的回归函数模型进行了累积入渗量I、特征湿润锋Zmf预测值和实测值之间的精度检验,结果表明其满足精度要求。

In this paper,it used the specific size and special sand mold simulate the same effective surface porosity,different depths of the large pore domain,water infiltration under the conditions of study in which three-dimensional moisture migration behavior.Experimental studies have shown that the existence of macropores resulting in water infiltration wetting front severe turbulence in the early infiltration,but it gradually over a smooth transition and its stability time relativity with the depth of macropores Z.The macropores domain filled with water rapidly and reach the large domain at the bottom of the macropore domain,causing the initial vertical and radial water infiltration,respectively.The cumulative amount of infiltration I increases with the depth of macropore.The characteristic of the deepest values of wetting front Zmf was the wetting for the process of infiltration which was the center of the macropore domain.Laboratory analysis Zmf and Z was around the same function but different coefficients in the point which the time before and after the turning point Tn.In the paper,it established the regression function model of the cumulative amount of infiltration I,wetting front Zmf and use the deviation function In carried out the accuracy test between the predictive value and the measured value,results shows that the precision of its requirements is good.