A Practical Method to Predict the Occurrence Time of Storm-Induced Shallow Landslide Considering the Underlying Impermeable Bedrock

The underlying impermeable bedrock affects the infiltration process of storm-induced shallow landslide which significantly influence the slope stability. In contrast to most existing methods that evaluate slope stability assuming the slope as infinite model without underlying bedrock, this paper presents a practical method for predicting storm-induced slope failures considering the effect of underlying bedrock on rainfall infiltration. The proposed method evaluates the depth of the wetting front based on actual rainfall data, considering the soil-rock interface as the boundary of infiltration. Furthermore, the factor of safety (FoS) of the slope during the rainfall was obtained to predict the occurrence time of landslide. Then, a comparison was carried out between estimated landslide occurrence time using actual rainfall data and simplified rainfall patterns. The influence of bedrock on the obtained results of landslide occurrence time was also studied through an illustrative case study of a landslide in Wanqingshan Village, Zhejiang Province, China. The results showed that the depth of the wetting front obtained using the simplified rainfall patterns differ greatly from the actual depth. While considering the influence of bedrock and using actual rainfall data, the computed FoS of the slope would reflect the real occurrence time of a landslide. The method proposed in this paper provides a practical tool to predict the occurrence time of storm-induced shallow landslides which may be helpful for the early warning of such landslides.