Numerical Simulation And Risk Analysis Of Barrier Lake Break Flood

China has the richest natural conditions in the world,and coexist with many natural disaster risks.With the global climate change in recent years,China is constantly suffering from natural disasters such as floods,droughts,landslides and earthquakes.At the same time,it may be accompanied by secondary disasters,which seriously restricts the development of our economy and affects the lives and property of our people Safety.Landslides are relatively common natural disasters.Once landslides occur on both sides of rivers,they often block river channels and form barrier lakes.The 2008 Wenchuan earthquake formed a total of 34 barrier lakes.In 2018,two large-scale barrier lake dangers occurred in the Jinsha River and the Yarlung Zangbo River in the same location,which caused huge losses to property of the people in the downstream.The break of the barrier lake will generally form a huge destructive flood process,At present,there is no effective means for the prediction and prevention of the barrier lake.It accurately predicts the process of the barrier lake collapse and the evolution of the destructive flood downstream Work plays a decisive role.In this paper,the Baige Barrier Lake is taken as the research object,and the flood calculation model of the barrier lake break and cascade hydropower station is established by integrating the barrier lake break theory,the two-dimensional flood evolution theory and the reservoir flood regulation theory.Based on the analysis of the Baige barrier body material,the flood process of the Baige barrier lake break was back analysised,and the parameters suitable for the calculation of the break flood of the barrier lake in the upper reaches of the Jinsha River were proposed.The reliability of the model was verified by back analysis of Baige Barrier Lake,and the flood process of the Baige barrier Lake break that may occur again in the future was predicted.The flood process of the cascade hydropower station under construction was simulated and analyzed Risks during the construction of downstream cascade hydropower stations.At the same time,the residual body of the barrier body that has taken manual intervention is analyzed to verify the feasibility and necessity of manual removal of the residual body.The main research contents and results are as follows:(1)In this paper,based on the measured breaking flood process of Baige barrier lake,the DB-IWHR dam-breaking flood calculation program is used to analyze the flooding of Baige barrier lake,and the inversion calculation method for the "10.10" Baige barrier lake without measured data is proposed,Combining the material characteristics of the "11.03" Baige barrier lake and the measured flow process,the break process is reversed.The calculation parameters for the break of the barrier lake composed of similar materials in the upper reaches of the Jinsha River are also proposed.(2)Based on the DB-IWHR dam-break flood theory and GAST flood evolution program,combined with the reservoir flood control calculation method,a cascade reservoir flood simulation model was established and verified by the "11.03" Baige barrier lake actual flood data.The error of peak discharge at the barrier lake of the model is only 0.1%,and the error of peak discharge at the downstream Lawa hydropower station is 2.8%.and the error of peak discharge at other hydropower stations is small.The difference of the highest water level of flood regulation is 1.68m at Lawa,and the simulation results are relatively conservative and safer in actual engineering.(3)The Baige landslide body is in a continuous creep state,and the maximum amount of possible one-time landslide instability is 2.2 million m3?3.4 million m3.The elevation of the dam formed by the landslide body is estimated to be 2952.5m.Based on the current standard,the flood process of the Baige barrier lake break was simulated and calculated.On this basis,the risk analysis of the downstream cascade hydropower stations under construction was carried out.(4)After the "11.03" Baige barrier lake broke out,human intervention was carried out on the dam residual body.The largest possible landslide instability may form the dam body accumulation height of 2944.5m.Under the "5-Years of flood" working condition,the calculation of the potential formation of the barrier lake break process was simulated,and the flood process of the cascade hydropower station under construction in the downstream was simulated.The risk analysis of the cascade hydropower station under construction in the downstream was conducted to verify the feasibility and necessity of the manual removal of residues.Predictive analysis of the risk of the formation of Baige barrier lake again.(5)This paper combines the DB-IWHR dam-break flood analysis theory,GAST flood evolution model and reservoir flood control theory to establish a cascade reservoir flood simulation model.The model can quickly analyze the dam-break flood process and the downstream cascade reservoir flood process.The calculation is accurate and fast.The GAST model uses GPU acceleration technology.In the large-scale space from Baige to Suwalong,the calculation time is only more than 40 minutes,and the calculation efficiency and accuracy are greatly improved.The model can be applied to rapid flood analysis when cascade hydropower stations exist in the downstream of the barrier lake,and provide theoretical guidance for the development of emergency rescue plans.