A sliding block model for the runout prediction of high-speed landslides

A sliding block model is developed for predicting the runout of high-speed slide-like landslides, based on the analysis of the dynamic mechanism of high-speed landslides. This model adopts the limit equilibrium analysis approach and incorporates mass dynamics and soil deformation into the calculation of soil movements. The critical state is considered as the initial stress state, and the interslice forces are obtained considering the equivalence of deformation energy. It is possible, applying this model, to simulate the whole travel process of the soil mass from the onset of the landslide and to predict the travel speed of the soil mass and the hazard area of the landslide. Application of the model to the Sale Mountain landslide and the Tianshui Forging Machine Factory landslide in China gives reasonable results in comparison to the field observations. The calculated results illustrate that (i) the fundamental causes of the high speed are the decline of the resultant friction force during sliding and the rapid and large fall of the centre of gravity of the back part of the slide mass; and (ii) the slide mass generally moves as a whole during the middle sliding stage, and the front part of the slide mass is often in a state of relaxation, even extension, at the end of the movement.Key words: high-speed landslides, dynamic analysis, runout distance, block model.