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.