Study On Flood Control Evaluation Of Bridge In Reservoir Area

Nowadays, the new phenomenons of bridge of new or planning in river area have arisen, angle between flow and normal of bridge axis is more and more big,and there is appers long-distance riverine bridge. Based on the basic methods of flood control evaluation of bridge, use the principal component analysis to classify the calculation parameters. Based on the problem of unbalance of fluvial sediment between deposition and erosion, the paper evaluated the flood control evaluation of bridge in the Hekou Reservoir, and to the river of balance of fluvial sediment between deposition and erosion, made three bridges in the Yanguo Gorge Reservoir as a case to evaluate the value of the scour and backwater; To compare the value in different methods with the results obtained in the hydraulic physical model, ultimately discussed particular details on the flood control evaluation of bridge in reservoir area. The primary research achievement is in below.(1)Through principal component analyzing, the common flood control evaluation parameter of empirical formula can be classified three sorts:hydrological informations, fluvial characteristics, parameters. For the evaluating of particular bridge, the variable is the location and the area of piers damming water.(2) Predicting the riverbed evolvement tendency of unbalance of fluvial sediment, the elevation of the riverbed steadily would be higher than the unbalanced present one. The results show that the evaluating the value of backwater and general scour would be lower than present, while the value of local scour would almost be the same, but water level is higher than present.(3)The values of backwater calculated by different formula indicate that the interference on the area of backwater in railway standard formula is more than that in Road standard formula. The value in road standard is more corresponding to the predicting value in the hydraulic physical model. It is suitable to use the formula—the value of backwater by piers+the area of marginal bank*marginal coefficient—to evaluated the area of backwater when the piers are constructed in both main channel and flood plain, while it is suitable to consider the area of backwater by piers only when the bridge is along the streamline. It is suitable to use numerical modelings or hydraulic physical models to evaluate in complex channel. It would get a larger value to plus the single value of backwater when handling the bridge group problem, and the walue Is not suitable for design. (4) The scour calculation indicate that the values of general scour calculated by the two empirical formulas get big differences. The value calculated by the simplified formula64-2would be larger. The values of partial scour calculated by the two empirical formulas would almost be the same. A larger current obstruction area will get a larger value of scour. The value only considering the area of backwater by piers is nearly corresponding with the results obtained in the hydraulic physical model. The value calculated by the empirical formulas is also nearly corresponding with the results obtained in the hydraulic physical model when the scour has not touched bedrock.(5) With the increase of non-flood engineering construction, the administrative department should formulate more intensive rules, confirm relevant concepts and regulate engineering project. I suggest to adding other restrictive condition to ascertain the flood control standard, which provide a more economic and reasonable decision basis for engineering construction.