Alert velocity method for landslides with step-like deformation in the Three Gorges Reservoir area

Voight's relation approaching the failure is found through the analysis of landslide acceleration and velocity of 35 different landslides.The final acceleration phase of the landslides cannot be identified due to the step-like deformation of the landslides in the Three Gorges Reservoir area,so the failure time of the landslides cannot be directly predicted with the model.Therefore,a much simpler and more practical method has been suggested to assess the landslide phases by means of velocity threshold values on the basis of the Voight model.According to different demands of risk level,alert velocity(corresponding to 30,15 and 7 days before predicted failure) can be computed according to the Voight's model and the parameters of the method are obtained with the nonlinear regression.The feasibility of the method is validated through the case analyses of the Xintan landslide and the Baishuihe landslide.The results show that the prediction and the monitoring data are very similar and the method plays an important role in predicting the landslides with step-like deformation.