具有砂质夹层的土壤连续函数入渗模型

实验研究表明,在具有砂质夹层土壤的积水入渗过程中,其累积入渗量随时间的变化存在着由非线性入渗关系逐渐转入线性稳定入渗的两个阶段.在已有的研究成果中,对此入渗过程大多采用以进入稳渗阶段的时间为界,分段对其进行数学模拟.本文提出将地表入渗通量随时间的变化视为两部分入渗过程叠加的思路,即一部分视为稳定入渗,其稳渗率与转入稳渗阶段后的量值相等;另一部分视为满足上层土体储水需求的非稳定入渗,其入渗率为入渗时间的函数,并在整个入渗过程进入稳定入渗阶段时,其量值趋近于零.在此思路与假设前提下,对具有砂质夹层土壤的入渗过程建立一个完整的连续函数入渗模型.该模型经实测资料验证,不仅更能符合具有砂质夹层土壤的入渗客观规律,而且具有较好的计算精度.

A Continuous Infiltration Model for Soil Interlayered with Sand

Experiments have shown that,for the infiltration process in soils with sand interlayers,the changing of cumulative infiltration volume with time included two stages: an initial non-linear stage,and a gradually-formed linear,stable stage.Most current studies modeled the two stages separately based on the time that the linear,stable stage had been reached.This paper proposed a continuous approach by separating the initial,non-linear stage into two independent sub-processes.The first sub-process was for stable infiltration,and its rate equaled that in the second,stable stage.The second sub-process was a transient process for filling the storages in the upper layer soil,and its rate varied with lapsing time,which eventually diminished after entering the second stage.By incorporating this approach,the entire infiltration process could be fitted into a single model.Experiment proved that,not only could the model better describe the physical infiltration process,but also achieved better accuracy.