Numerical Modeling of Anhui Debris Flow

Abstract

A mathematical model is formulated to simulate dam-break transient debris flows, in which the debris and water mixture is assumed to be isotropic and continuous. In terms of its viscoelastoplasticity, a three-dimensional (3D) rheologic model for Bingham body is used to describe the relationship between the stress tensor and the rate of strain. Only the deformation caused by the deviatoric stress tensor is taken into account. Under the prior considerations, the governing equations for two-dimensional (2D) depth-averaged transient debris flows are obtained by integrating the equation of continuity and equations of motion over depth for 3D flows. To deal with the transient and high-speed features of dam-break debris flows, the derived governing equations are discretized and solved using the method of characteristics. The model is applied to simulate the dam-break debris flow of April 30, 1986, for the Jinshan debris reservoir in Anhui, China. The debris and water mixtures reach as far as 900 m downstream from the initial tailings dam site, with a depth of 1.7 m near the tailings dam and 1.0 m at 900 m downstream. These model results are in good agreement with the available observations.