A 3D slice–based analytical calculation formula for the reservoir landslide velocityA 3D slice–based formula for the reservoir landslide velocity

The landslide velocity in reservoirs is a key index in evaluating landslide hazards. The conventional 2D velocity calculation method cannot consider the 3D characteristics of a landslide, and the obtained landslide velocity is inconsistent with the actual value. This article proposes a 3D landslide velocity calculation method considering the pore water pressure and water drag. The landslide was divided into 3D slices, and a stress analysis was performed. The acceleration and velocity of the landslide were obtained from the motion equation. Taking the Wangjiashan landslide in the Baihetan reservoir area of Jinsha River as an example, a cohesionless sliding experiment was conducted in a large-scale physical model to verify the calculation method. Considering the cohesion, a 3D calculation model of the Qianjiangping landslide was evaluated, and the error in the velocities was 6.19%, which was evidently higher than that obtained when using other analytical calculation methods. The sensitivity of this method to parameters was lower than that of the 2D slice method. The new method can be used as an effective analysis method to predict the velocity of landslides, and a comparative analysis with various calculation methods can provide a reference for selecting the optimum calculation method for the reservoir landslide velocity.