Assessment of landslide hazard often requires a good knowledge of the landslide characteristics. To investigate the dynamic runout process of the landslide across 3D terrain, a three-dimensional model using spring-deformable-block model is proposed. On the assumption that the motion form of landslides is continuous and variable, the sliding body is divided into lots of columns. The model is based on a stability analysis of landslides and allows taking the deformation of sliding body into account. Considering the force and moment equilibrium of deformable columns and the principle of conservation of energy, a three-dimensional sliding body is simplified by a series of deformable blocks with different dimensions. According to the accumulation and the release of the deformation, the sliding body acceleration, velocity and displacement formulas are established. Correlating well with the discrete element method, the present results are satisfactory in describing the dynamic process of landslides and predicting the impact areas of the post-failure sliding body. Finally, the present model is applied to analyze the sliding time, the maximum velocity and displacement of the sliding body of Jiweishan landslide in Wulong, Chongqing Southern China. By comparing with existing numerical results, the model shows good agreement with the previous ones.
Landslides which defined as the movement of a mass of rock, debris or soil down a slope are characterized by long-runout displacements and high velocity (Cruden 1991). Even far away from the origin location of the slope, significant destruction still can be brought by rapid landslides through the sliding path. However, sometimes their potential for destruction can't be practically reduced by reinforcement of the source area (Hungr 1995). Prediction of post-failure motion is needed in the hazard assessment as an important part in case that a potential source of a landslide is detected. Therefore, engineering risk analysis emerged, especially the runout analysis which is applied to estimate the potential hazard area (Hungr 1995). In order to design protective measures, run out parameters such as the maximum displacement reached, the landslide velocity, and the distribution of the deposits should be determined through quantitative method during the runout analysis.