Investigation of the effects and mechanisms of the wetting-Induced deformation behavior of compacted loess in Yan’an, China

Wetting-induced deformation of loess is a key factor contributing to frequent geological disasters in the Loess Plateau region. Therefore, investigating the wetting deformation behavior of loess is of great significance for disaster prevention and mitigation in this region. In this study, a series of graded wetting deformation tests were carried out to examine the evolution of loess deformation during wetting process. Scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) techniques were also employed to analyze the microstructural changes in loess. Results indicate that pore collapse in low dry-density specimen (ρd = 1.60 g/cm³) causes large pores to gradually transition into medium and small pores during the wetting process. As both vertical pressure and water content increase, the wetting-induced deformation potential first increases and then declines. In contrast, high dry-density specimen (ρd = 1.75 g/cm³) exhibit a relatively small wetting-induced deformation potential, primarily due to their denser soil structure, and stronger cementation. Furthermore, the wetting-induced deformation of loess is essentially a combined process of large pore collapse and particle rearrangement, during which the soil structure transitions from weak to stable cementation. The obtained findings provide a theoretical foundation for understanding the mechanisms of wetting-induced geological hazards in loess regions and offer significant practical value for disaster prevention and mitigation.