Investigations of the Effect of Artificial Rainfall on the Pore Water Pressure and Slope Surface Displacement of Loess Slopes

Abstract

Understanding the rainfall-triggering mechanisms influencing loess landslides and developing targeted prevention and control strategies are critical challenges in engineering. This study focused on a representative landslide-prone area in Huxian County, Xi’an, China, and field experiments involving artificial rainfall simulations were conducted. Utilizing the annual rainfall statistics for Huxian County, three distinct rainfall scenarios—light, moderate, and heavy—were established. The aim was to explore the correlation between internal pore water pressure and temporal and depth-related changes during the postrainfall stage. At the same time, reflective patches were placed on the slope and total stations were used to monitor the impact of different rainfall intensities on slope displacement. Based on the field data, a three-dimensional simulation validation was executed using Surfer software. Our findings suggest that increasing rainfall intensity directly correlates with higher internal pore water pressure. As the rainfall persisted, the daily amplitude of pore water pressure initially surged before moderating, ultimately exhibiting a logarithmic trend with depth. The effective influence depths of the daily amplitude of pore water pressure during light, moderate, and heavy rainfall stages were found to be 1.6, 2.2, and 5.0 m, respectively. Following cessation of the rainfall, the surface pore water pressure underwent substantial change, and the daily amplitude rapidly declined before stabilizing. Slope displacement consistently increased from the summit to the base throughout the rainfall stages, with the base being most susceptible to sliding instability. The maximum displacement at the foot of the slope was in Columns 3–5, with a maximum displacement value of 1,158 mm. Proximity to the slope’s base correlated with greater gravitational and downward forces. Specific maximum displacement values were recorded at different locations along the slope, revealing the most significant changes along the slope’s centerline. This work will contribute to the effective management and landslide prevention of loess slopes.