New insights and modeling of the evolution of loess infiltration characteristics under multiple rainfalls induced by climate on the Loess Plateau of China

Abstract

The study investigates how climate-induced multiple rainfall infiltrations on the Loess Plateau result in microstructural changes in loess, subsequently influencing its infiltration characteristics. To simulate the loess infiltration properties under multiple rainfall events, three infiltration tests were performed using a vertical infiltration apparatus. Additionally, SEM and NMR techniques were employed to examine the microstructural alterations in loess pre- and post-infiltration. The findings reveal that in specimens with low dry density, multiple infiltrations primarily cause pore collapse, significantly reducing infiltration rate, wetting front advance velocity, saturated volumetric water content, and the slope of the SWRC. Conversely, in high dry density specimens, cementation and carbonate dissolution dominate, leading to the expansion of small pores and enhanced connectivity, which results in opposite infiltration characteristics. Based on these experimental outcomes, the traditional isotropic SWRC model was extended to account for deformation conditions by incorporating two additional parameters. This study's results hold both practical and theoretical significance for mitigating natural disasters induced by rainfall in loess regions.