Abstract: The classical Green-Ampt infiltration model is simple in calculation and widely used in the study of soil infiltration. However, there exist some certain theoretical assumptions for the obvious dry-wet separation interface in the treatment of wetting front in the model. In view of this, based on the layered model of saturated zone-unsaturated infiltration zone and combined with Darcy’s law, a theoretical formula of the thickness relationship between the saturated zone and the unsaturated infiltration zone during infiltration was deduced in this paper and a theoretical model of water profile was proposed, which can eliminate the traditional assumption of the thickness relationship between the saturated zone and the unsaturated infiltration zone. On the basis, an improved Green-Ampt model considering the shape of soil moisture profile and the equivalent parameters in the unsaturated infiltration was established. The model was verified by experiments and finite element numerical simulation. The results show that the model has high accuracy and good adaptability to different types of soil. Meanwhile, the model is simple to solve with clear physical meaning parameters, and is convenient for engineering application.

Key words: Green-Ampt model, moisture profile model, unsaturated infiltration zone, infiltration depth, unsaturated seepage