Numerical Simulation Of Reservoir Dam Breaking Flood Based On MIKE

China is one of the countries with the largest number of rivers in the world.In order to make full use of hydropower resources,China has built power stations on many rivers,which have formed large and medium-sized reservoirs.Although the frequency of dam breaks is low,the dam is subject to over-frequency floods,strong earthquakes and other damages,and there is a risk of collapse,which may induce dam breaks.The main characteristics of the dam-breaking flood are sudden occurrence,short formation,rapid flooding,high water level,large flood volume and fast speed.After the dam flood occurs,the flood wave rapidly advances to the downstream area in the form of swell waves and standing waves.Downstream river areas are often difficult to protect.The dam-breaking flood destructive power and propulsion speed are much larger than the general floods.Once the reservoir dam breaks,most towns and villages along the downstream river will be submerged or destroyed.In view of the large impact of the dam-breaking flood on the downstream area,in order to prevent this,this study uses two cascade hydropower stations upstream of the Hanjiang tributary of Hubei as the dam-breaking research object,and uses the MIKE series software to establish a one-dimensional and two-dimensional coupling model.The reasons for the dam break,the method of collapse,the shape of the breach and the duration of the collapse,simulate the process of dam flood in different rivers and urban villages under different schemes,analyze the flood immersion results,and develop flood control plan for the downstream areas.This analysis has obtained the following main analytical research results:(1)In the simulation process,the roughness parameter is segmented according to the characteristics of the river section and the characteristics of the water flow.The overall roughness range is between 0.028 and 0.048,and the error of the rate is within the allowable range.(2)The dam-breaking flood shows a single wave propagating downstream.As the dam-breaking water level increases,the maximum flood peak flow of the crater also increases.The maximum flooding flow rate of each scheme is greater than the maximum flooding rate of the flood in one year.The maximum discharge flow at the breach of scheme 1 is 183822m~3/s,which is 8.09 times of the maximum flow of the flood in the basin.The maximum discharge flow at the breach of scheme 7 is the basin 1.2 times the flood in a million years.(3)The maximum flood peak flow and the highest water level along the dam break flood show a decreasing trend from upstream to downstream.(4)The analysis clearly defines the flood time characteristics.The five downstream sections have the same collapse duration,the higher the water level is,the faster the arrival time of the dam break flood;the longer the same collapse duration,the slower the arrival time of the dam break flood;the same collapse duration,the different water level,the water level The higher the flood peak,the slower the arrival time;(5)The dam breach flood of each scheme is in the county area of the key area.The maximum velocity distribution is in accordance with the general hydrodynamic law.The flow velocity of the water flow is the largest near the deep channel of the river,and the flow velocity is larger at the bend of the river and in the narrow valley.(6)The dam-breaking flood has a great impact on the downstream county area.According to the analysis of the largest submerged area in the county area,the submerged range of each scheme is between 1.74km~2 and 9.20km~2,accounting for 5.05%~42.26%of the total urban area(21.77km~2).(7)Considering the situation of the most unfavorable plan flooding area,a flood control transfer plan for the downstream area was formulated.