Abstract: The Tanjiawan landslide in Zigui County is a typical largescale landslide within colluvial in the Three Gorges Reservoir area. In recent years, it has undergone a significant deformation due to the rainfall, posing a serious threat to people’s lives and property. Based on the geological environment of the landslide area and the cumulative displacement curve, an analysis was conducted on the relationship between the landslide deformation and the rainfall. The study shows that the rainfall is the main triggering factor for the deformation of the Tanjiawan landslide. The cumulative displacement curve exhibits a “stepped” characteristic under the continuous rainfall and heavy rainfall conditions, with a noticeable lag in the occurrence of stepped deformation. The threshold displacement rate for the accelerated “stepped” movement of the Tanjiawan landslide is 17 mm/day. The threshold value for antecedent rainfall and the current rainfall in the antecedent rainfall + the current rainfall model of the Tanjiawan landslide are 10 mm and 13 mm, respectively. After the end of the continuous rainfall, it takes 5 ~ 8 days for the displacement rate of monitoring points to return to normal. The impact of a single rainfall event on the landslide deformation lasts for 8 days.

Key words: Rainfall-Induced Landslide, Deformation Characteristics, Stepped Curve, Threshold Value