The researchers conducted indoor model tests to study how heavy rainfall affects loess slopes in Tianshui, China. They varied the slope gradient and rainfall intensity to see how they impact slope stability. The results showed that higher rainfall intensity leads to faster infiltration rates, with heavy rainfall increasing soil moisture by over 10%. Steeper slopes have slower infiltration rates. Under heavy rainfall, loess slopes are more likely to slide from bottom to top, while light rain can trigger retrogressive landslides.