Comprehensive Analysis Of River Bend Bridge Water

Along with the development of the national economy, and the technology advancementof the bridge design and construction, an increasing number of bridges have been constructedin the rivers by the state. However, natural rivers especially mountain rivers are usuallycompositions of a series of bends and straight channels. So, the research of the bend flow lawin bridge zone occupies a very important position in many realms like water conservancyengineering and bridge engineering.The hydraulic model test and the numerical simulation are two basic methods ofresearching bend flow. On the basis of engineering practice, this study makes the generalizedbend model of water tank, describes the design of the physical model and manufacturemethod, and conducts the contrast test on different engineering plans, and also measures thewater flow regime, the back-water height in front of bridge, the sphere of influence and theerosion and siltation variation of the riverbed under different flow rate, with or without piers.Based on the test data, this thesis provides a preliminary analysis on the water flow andscouring phenomena of the bend bridge zone. The results show that, from the aspect of flowvelocity, after the hydraulic model test, the closer it is to piers the greater the changes of theflow velocity vector; the larger the flood discharge the greater the flow velocity variation nearpiers. From the aspect of water level, the water level in concave bank is higher than that of theconvex bank, and the water level ratio continues to increase when drops to the bend roof. So,the construction of the bridge makes the decrease of the ratio of water level in bend channellessened contrast with no piers. From the aspect of scouring, the bigger the flow the greaterthe scouring sphere of the riverbed, the greater the erosion intensity, the deeper the scouringpit; the local scour of the concave bank near the bridge is bigger than that of the convex bank.Convex bank near the bridge pier and local scour are compared with theoretical calculation ofgeneral erosion formula slightly smaller, use the formula to calculate river pier scour whenneeded some correction.Furthermore, in accordance with the working condition and law of each group, athree-dimensional numerical model is established by using the software of FLUENT, thisthesis studies the change law of the flow structure in river bend bridge zone, and providesreference for the bridge calculation in river bend. Finally, comparing the calculation resultswith test results, finding out that the mathematical model is consistent with results of thehydraulic model, and fully verifies the reliability of the numerical calculation.