Study On Application Of Two-dimensional Hydrodynamic Model On Flood Protection Impact Evaluation Of The Laoha River Railway Bridge

Since the 21 st century, with the rapid economic development and the social progress, the national infrastructure investment ratio increases year by year, then the infrastructure projects within the scope of the river management are continuing without end. In these circumstances, if the preliminary design and the construction cannot meet the flood control standards, there will be a series of problems, including the water levels banked-up, the deflecting flow, the scouring, and so on, which would influence to a certain extent for the natural river stabilization, the flood control and flood prevention, the flood management. Combined with the engineering examples of the super major railway bridge in Laohahe River, the paper studies and discusses the basic problem of impact assessment of the bridge crossing the river on the flood control.According to the simulation analysis of the influence of the buildings in the river on the river flood flow regime, the one-dimensional model has the advantage of the low requirement basic data and the good operation efficiency and has the disadvantage of the lower degree precision of the calculation results. For the three-dimensional model, the precision degree of the existing data is morehigh, the boundary conditions and the parameter identification conditions are very much and the operation cycle is long. Considering the flow in the vertical direction, the model is suitable for the environmental dynamics with complicated water flow change. There are fewer applications for this project. For the simulation analysis of river local flow regime at home and abroad, the two-dimensional model has the more application and the results could meet the requirements of evaluation and analysis, the operational efficiency and cycle are suitable for the this project. Therefore, this model is widely used in the hydrodynamic simulation analysis of the river, river channel and the lakes.The Hydrodymamie Module of MIKE21 software and the two-dimensional hydrodynamic model of the Hydro Info hydraulic information system are adopted for the research, the former is developed by the DHI(short for Danish Hydraulic Institute) and the latter is developed by the Dalian University of Technology. Based on the project related information, the boundary conditions are determined for the simulation and calculation. The model is built to simulate dynamically the flow regime of the Laohahe bridge site under the conditions of the design flood. Through the post-processing of the calculation results, the required data results and the charts are extracted and the calculation results are analyzed, then the corresponding conclusions are obtained. The paper evaluates objectively the flood control influence of the railway bridge in Laohahe River, proposes the corresponding prevention measures and suggestions according to the engineering design, which could provide the basis for the river management department in the flood control management.This research also could provide with the reference valuable theory and method for the flood control impact assessment of construction projects within river in future.