Abstract: The theoretical analysis of water infiltration in loess is very important for predicting deformation and strength weakening of loess. However, there are still some problems lying in the application of existing Green-Ampt infiltration analysis model using into homogeneous foundation of loess area. Based on the assumption of saturated-unsaturated stratification of loess, the modified infiltration model also considered the actual variation of permeability coefficient of soil with the depth of infiltration. The proposed approach modified the Green-Ampt model with an actual case for validation. Combined with the relation between Philip model and Green-Ampt model, as well as the actual permeability coefficient changed with time, the hydraulic parameters were estimated by measuring the variations of cumulative infiltration and water content with time. The results showed that compared with WGAM and Kostiakov models, the modified model was more effective in loess area. Based on the modified model, the effects of saturated permeability coefficient, saturated water content, initial water content and matrix suction on water infiltration depth were analyzed. The sensitivity of the parameters was analyzed and compared. It was found that the change of initial and saturated water contents of soil greatly influenced the calculation results of the model. The present research is of great significance for the relative investigation of infiltration in loess area.

Key words: loess, infiltration, Green-Ampt model, stratified hypothesis