Abstract: Rainfall infiltration is a key factor which induces landslides. Researching the law of rainfall infiltration in slope is of crucial significance for the prediction and prevention of landslides. The traditional Green-Ampt model and the improved Green-Ampt model both assume that the infiltration process is uniform and saturated, ignoring the existence of unsaturated zone above the wetting front. In view of this, we analyzed the distribution law of matric suction in slope first of all based on Darcy’s law; and in subsequence, we obtained the functional relation of water content in the wet zone of slope varying with depth in association with the VG model of unsaturated soil; finally, we derived a rainfall infiltration model considering the unsaturated characteristics of soil using the improved Green-Ampt model, and applied the model into infinite slope stability analysis. Results demonstrated that, compared with numerical solution and existing models, the proposed infiltration model in consideration of the unsaturated characteristics of soil reflects more accurately the process of rainfall infiltration. In addition, the stability coefficient calculated based on the proposed model better reveals the change rule of slope stability under constant rainfall intensity, which proves the correctness and applicability of the model.

Key words: rainfall infiltration, VG model, Green-Ampt model, infinite slope, stability analysis