Numerical simulation method for predicting a flood hydrograph due to progressive failure of a landslide dam

Reducing the damage due to landslide dam failures requires the prediction of flood hydrographs. Although progressive failure is one of the main failure modes of landslide dams, no prediction method is available. This study develops a method for predicting progressive failure. The proposed method consists of the progressive failure model and overtopping erosion model. The progressive failure model can reproduce the collapse progression from a dam toe to predict the longitudinal dam shape and reservoir water level when the reservoir water overflows. The overtopping erosion model uses these predicted values as the new initial conditions and reproduces the dam erosion processes due to an overtopping flow in order to predict a flood hydrograph after the reservoir water overflows. The progressive failure model includes physical models representing the intermittent collapse of a dam slope, seepage flow in a dam, and surface flow on a dam slope. The intermittent collapse model characterizes the progressive failure model. It considers a stabilization effect whereby collapse deposits support a steep slope. This effect decreases as the collapse deposits are transported downstream. Such a consideration allows the model to express intermittent, not continuous, occurrences of collapses. Field experiments on the progressive failure of a landslide dam were conducted to validate the proposed method. The progressive failure model successfully reproduced the experimental results of the collapse progression from the dam toe. Using the value predicted by the progressive failure model, the overtopping erosion model successfully reproduced the flood hydrograph after the reservoir water started to overflow.

Numerical Simulation of Scouring in Overtopping Dam-break Flow

<p>Overtopping dam-break flow has great harm to the earthen embankments due to the hydraulic erosion. Some researchers have carried out relevant model experiments, but it is difficult to achieve the experimental conditions for the actual situation. The common numerical simulation is to express the scouring process through the empirical relationship, which obviously could not reflect the real scouring process. In this paper, a new overtopping erosion model using Smoothed Particle Hydrodynamics (SPH) is proposed. When the shear stress on the sediment SPH particle exceeds the critical stress, the erosion process begins. Then, when a sediment SPH particle is completely eroded, it will begin to move and is described as a non-Newtonian fluid. The un-incipient sediment particles are treated as boundary. This model is well validated with plane dike-breach experiment, and has also achieved a good agreement with erodible bed dam-break experiment.</p>

Overtopping Failure of a Reinforced Tailings Dam: Laboratory Investigation and Forecasting Model of Dam Failure

Overtopping failure of reinforced tailings dam may cause significant damage to theenvironment and even loss of life. In order to investigate the feature of overtopping of the reinforcedtailings dam, which has rarely appeared in the literature, the displacement, the phreatic level and theinternal stress of dam during overtopping were measured by a series of physical model tests. Thisstudy conclusively showed that, as the number of reinforcement layers increased, the anti-erosioncapacity of tailings dam was notably improved. It could be supported by the change of the dimensionof dam breach, the reduction of stress loss rate, and the rise of phreatic level from the tests. Based onthe erosion principle, a mathematical model was proposed to predict the width of the tailings dambreach, considering the number of reinforcement layers. This research provided a framework for theexploration of the overtopping erosion of reinforced tailings dam, and all presented expressions couldbe applied to predict the development of breach during overtopping.