The influence of rainfall infiltration on the formation of loose layer on the surface of earthen sites in arid area

High-frequency light rain infiltration-rapid evaporation process is the key driving force for the development of loose layer on the surface of earthen sites in the arid region of Northwest China. According to the simulation experiments, it has been observed that after rainfall infiltration, the cementation between soil particles deteriorated, and particles mainly composed of powder particles(0.005~0.075 mm) migrated downward. Simultaneously, particle migration induces an increase in soil pore volume, characterized by a dominance of macropores(> 32 μm). These changes in particle migration and pore structure directly contribute to the formation of a loose layer. The thickness of this loose layer primarily depends on rainfall intensity rather than cumulative rainfall cycles. This study reveals the influence of rainfall infiltration on the formation of loose layers on the surface of earthen sites in arid areas, which is of great significance for the preventive conservation of earthen sites.