An Improved Infiltration Model for Unsaturated Loess Considering Deformation

Loess collapsibility under wetting conditions poses significant challenges to slope stability and infrastructure. To address limitations in traditional Green–Ampt infiltration models under stress, this study develops a modified model incorporating vertical stress-induced loess deformation. Key improvements include replacing the saturated permeability coefficient with a stress-dependent equivalent permeability coefficient and establishing a stress-sensitive matric suction parameter determination method. The model enhances predictions of wetting front progression and cumulative infiltration. Validation through one-dimensional soil column infiltration tests shows strong alignment between model outputs and experimental data, confirming reliability. With parameters obtainable from conventional tests, this model demonstrates practical value for soil–water dynamics analysis, deformation prediction, and water management in loess regions.