A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the t...A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the three-dimensional Reynoldsaveraged Navier-Stokes equations(RANS),the renormalization group(RNG)k-εturbulence model,suspended and bed load transport equations,and the instability discriminant formula of dam breach side slope,and the explicit finite volume method(FVM),a detailed numerical simulation model for calculating the hydro-morphodynamic characteristics of cascading dam breach process has been developed.The developed numerical model can simulate the breach hydrograph and the dam breach morphology evolution during the cascading failure process of landslide dams.A model test of the breaches of two cascading landslide dams has been used as the validation case.The comparison of the calculated and measured results indicates that the breach hydrograph and the breach morphology evolution process of the upstream and downstream dams are generally consistent with each other,and the relative errors of the key breaching parameters,i.e.,the peak breach flow and the time to peak of each dam,are less than±5%.Further,the comparison of the breach hydrographs of the upstream and downstream dams shows that there is an amplification effect of the breach flood on the cascading landslide dam failures.Three key parameters,i.e.,the distance between the upstream and the downstream dams,the river channel slope,and the downstream dam height,have been used to study the flood amplification effect.The parameter sensitivity analyses show that the peak breach flow at the downstream dam decreases with increasing distance between the upstream and the downstream dams,and the downstream dam height.Further,the peak breach flow at the downstream dam first increases and then decreases with steepening of the river channel slope.When the flood caused by the upstream dam failure flows to the downstream dam,it can produce a surge wave that overtops and erodes the dam crest,resulting in a lowering of the dam crest elevation.This has an impact on the failure occurrence time and the peak breach flow of the downstream dam.The influence of the surge wave on the downstream dam failure process is related to the volume of water that overtops the dam crest and the erosion characteristics of dam material.Moreover,the cascading failure case of the Xiaogangjian and Lower Xiaogangjian landslide dams has also been used as the representative case for validating the model.In comparisons of the calculated and measured breach hydrographs and final breach morphologies,the relative errors of the key dam breaching parameters are all within±10%,which verify the rationality of the model is applicable to real-world cases.Overall,the numerical model developed in this study can provide important technical support for the risk assessment and emergency treatment of failures of cascading landslide dams.展开更多
This paper presents results of model tests for the landslide dam failure of a single dam and cascade dams in a sloping channel. The dams were designed to be regular trapezoid with fine sand. A new measuring method nam...This paper presents results of model tests for the landslide dam failure of a single dam and cascade dams in a sloping channel. The dams were designed to be regular trapezoid with fine sand. A new measuring method named the labeled line locating method was used to digitalize the captured instantaneous pictures. Under two different inflow discharges, the morphological evolution and the flow patterns during one dam failure and the failure of cascade dams were investigated. The results indicate that when the inflow discharge is large, the deformation pattern of the downstream dam is similar to that of the upstream dam, and both dams are characterized with the overtopping scour throughout the dam failure process. When the inflow discharge is small, the upstream dam is scoured mainly through a sluice slot formed by the longitudinal incision, and the downstream dam is characterized with the overtopping scour. The data set presented in this paper can be used for the validation of numerical models and provide a reference for the flood risk management of cascade landslide dams.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U22A20602,U2040221).
文摘A cascading failure of landslide dams caused by strong earthquakes or torrential rains in mountainous river valleys can pose great threats to people’s lives,properties,and infrastructures.In this study,based on the three-dimensional Reynoldsaveraged Navier-Stokes equations(RANS),the renormalization group(RNG)k-εturbulence model,suspended and bed load transport equations,and the instability discriminant formula of dam breach side slope,and the explicit finite volume method(FVM),a detailed numerical simulation model for calculating the hydro-morphodynamic characteristics of cascading dam breach process has been developed.The developed numerical model can simulate the breach hydrograph and the dam breach morphology evolution during the cascading failure process of landslide dams.A model test of the breaches of two cascading landslide dams has been used as the validation case.The comparison of the calculated and measured results indicates that the breach hydrograph and the breach morphology evolution process of the upstream and downstream dams are generally consistent with each other,and the relative errors of the key breaching parameters,i.e.,the peak breach flow and the time to peak of each dam,are less than±5%.Further,the comparison of the breach hydrographs of the upstream and downstream dams shows that there is an amplification effect of the breach flood on the cascading landslide dam failures.Three key parameters,i.e.,the distance between the upstream and the downstream dams,the river channel slope,and the downstream dam height,have been used to study the flood amplification effect.The parameter sensitivity analyses show that the peak breach flow at the downstream dam decreases with increasing distance between the upstream and the downstream dams,and the downstream dam height.Further,the peak breach flow at the downstream dam first increases and then decreases with steepening of the river channel slope.When the flood caused by the upstream dam failure flows to the downstream dam,it can produce a surge wave that overtops and erodes the dam crest,resulting in a lowering of the dam crest elevation.This has an impact on the failure occurrence time and the peak breach flow of the downstream dam.The influence of the surge wave on the downstream dam failure process is related to the volume of water that overtops the dam crest and the erosion characteristics of dam material.Moreover,the cascading failure case of the Xiaogangjian and Lower Xiaogangjian landslide dams has also been used as the representative case for validating the model.In comparisons of the calculated and measured breach hydrographs and final breach morphologies,the relative errors of the key dam breaching parameters are all within±10%,which verify the rationality of the model is applicable to real-world cases.Overall,the numerical model developed in this study can provide important technical support for the risk assessment and emergency treatment of failures of cascading landslide dams.
基金supported by the National Basic Research and Development Program of China(973 Program,Grant No.2007CB714105)the National Natural Science Foundation of China(Grant No.50909067)
文摘This paper presents results of model tests for the landslide dam failure of a single dam and cascade dams in a sloping channel. The dams were designed to be regular trapezoid with fine sand. A new measuring method named the labeled line locating method was used to digitalize the captured instantaneous pictures. Under two different inflow discharges, the morphological evolution and the flow patterns during one dam failure and the failure of cascade dams were investigated. The results indicate that when the inflow discharge is large, the deformation pattern of the downstream dam is similar to that of the upstream dam, and both dams are characterized with the overtopping scour throughout the dam failure process. When the inflow discharge is small, the upstream dam is scoured mainly through a sluice slot formed by the longitudinal incision, and the downstream dam is characterized with the overtopping scour. The data set presented in this paper can be used for the validation of numerical models and provide a reference for the flood risk management of cascade landslide dams.