Three-dimensional Numerical Simulation Of Flood Propagation And Safety Evaluation Of Buildings

The economic losses caused by flood are increasing.Three-dimensional flood inundation simulation,a significant approach of flood prediction and prevention,can be adopted to identify the flood danger,evaluate the buildings safety under flood impact and formulate the response plan in advance to reduce the flood damage.Focusing on the three-dimensional flood inundation simulation,the dam discharge simulation,urban flood inundation simulation and the building deformation under flood impact are solved.The specific research contents and results are as follows:(1)Three-dimensional numerical simulation of dam discharge and flood routing in Wudu ReservoirThe digital dam model is constructed by integrating multi-source information.The three-dimensional hydrodynamic model is built based on the digital dam model to carry out the dam discharge simulation.Four working conditions are adopted,and the effectiveness and safety of the dam operation are evaluated by the spatial distribution of the flow field.The results show that the maximum discharge is 13800m~3/s,the length of hydraulic jump is 110m,and the maximum pressure at jet incident point is 500k Pa.Under the condition of design flood level,the maximum inundated area of downstream buildings can reach 203m~2,and the maximum flow depth is about 1m.The numerical simulation of dam flood discharge comprehensively accounts for the discharge capacity,pressure distribution,and energy dissipation efficiency of the dam,evaluating the operation conditions of the dam carefully and providing a visual reference for optimizing the operation and dispatching management of the dam.(2)Three-dimensional urban flood inundation simulation based on digital aerial photogrammetryThe image within 1832m~2 of the research area is collected by the UAV,and the digital city model including all features and landforms is constructed by using the automatic modelling process.On this basis,the three-dimensional urban flood inundation simulation is carried out to evaluate the flood danger caused by storm surge once in 100years.The results show that the existence of coastal levees can protect the safety of the city.The flood inundation area is concentrated within 200m along the coast,and 16.9%of the urban areas have a flow depth of more than 0.2m,bringing disasters to more than400 people in the area.The three-dimensional flood inundation simulation can display the spatial distribution and dynamic changes of disaster risk with high precision,and improve the scientificity of flood risk analysis.(3)Safety evaluation of buildings under flood impactThe numerical simulation of dam break flood impacting buildings is constructed,and the Eulerian two-phase flow model and smooth particle dynamics method are applied to solve the flow motion.The deformation characteristics of buildings under the flood impact are evaluated by fluid structure interaction and model test.The results show that the maximum total pressure of the upstream building surface is 1800N,and the deformation of the door and window is obvious,and the maximum deformation can reach 600μm,which results in the large deformation of the gable and roof on both sides.Moreover,the arrangement of buildings has different blocking effect on flood.The back-row buildings arranged in alignment along the flow direction still has to bear 20%flood impact,and the front row buildings arranged alternately bear 90%high-speed flow impact.By adopting the three-dimensional fluid structure interaction simulation and model test,the deformation and instability characteristics of buildings under the dam break flow are studied.The structural damage is evaluated by the material failure criterion,and the weak position of buildings is identified,providing an optimal design of buildings.